阅读说明：本技术 树脂成型体的制造方法 (Method for producing resin molded article ) 是由 荒谷凉子 于 2020-05-27 设计创作，主要内容包括：本发明提供树脂成型体的制造方法,该制造方法能够制造机械强度良好且物性的各向异性和翘曲少的树脂成型体。一种包含(A)热塑性树脂和(B)纤维素纳米纤维的树脂成型体的制造方法,其中,上述方法包括下述工序：准备包含(A)热塑性树脂和(B)纤维素纳米纤维的主供给材料(a1)、以及作为上述主供给材料(a1)的熔融处理产物的辅助供给材料(a2)的工序；将上述主供给材料(a1)与上述辅助供给材料(a2)熔融混合,得到树脂组合物(b)的树脂组合物形成工序；以及将上述树脂组合物(b)进行成型,得到树脂成型体的工序。(The invention provides a method for producing a resin molded body, which can produce a resin molded body with good mechanical strength and less anisotropy and warpage of physical properties. A method for producing a resin molded body comprising (A) a thermoplastic resin and (B) a cellulose nanofiber, wherein the method comprises the steps of: preparing a main supply material (a1) containing (a) a thermoplastic resin and (B) cellulose nanofibers, and an auxiliary supply material (a2) that is a melt-processed product of the main supply material (a 1); a resin composition forming step of melt-mixing the main supply material (a1) and the auxiliary supply material (a2) to obtain a resin composition (b); and a step of molding the resin composition (b) to obtain a resin molded article.)

1. A method for producing a resin molded body comprising (A) a thermoplastic resin and (B) a cellulose nanofiber, wherein the method comprises the steps of:

a step of preparing a main supply material (a1) containing (a) a thermoplastic resin and (B) cellulose nanofibers, and an auxiliary supply material (a2) that is a melt-processed product of the main supply material (a 1);

a resin composition forming step of melt-mixing the main supply material (a1) and the auxiliary supply material (a2) to obtain a resin composition (b); and

and (c) molding the resin composition (b) to obtain a resin molded article.

2. A method for improving the fiber opening property of cellulose nanofibers (B) in the production of a resin molded body comprising a thermoplastic resin (A) and cellulose nanofibers (B), wherein the method comprises the steps of:

a step of preparing a main supply material (a1) containing (a) a thermoplastic resin and (B) cellulose nanofibers, and an auxiliary supply material (a2) that is a melt-processed product of the main supply material (a 1);

a resin composition forming step of obtaining a resin composition (b) containing 2 or more types of cellulose nanofibers having different thermal histories by melt-mixing the main supply material (a1) and the auxiliary supply material (a 2); and

and (c) molding the resin composition (b) to obtain a resin molded article.

3. The method according to claim 2, wherein the 2 or more cellulose nanofibers different in thermal history have different fiber lengths from each other.

4. The method according to any one of claims 1 to 3, wherein a part of the resin molded body is used as the auxiliary supply material (a 2).

5. The method according to any one of claims 1 to 4, wherein the main feed material (a1) comprises 100 parts by mass of the (A) thermoplastic resin and 1 to 50 parts by mass of the (B) cellulose nanofibers.

6. The method according to any one of claims 1 to 5, wherein the constituent components of the main feed material (a1) are mixed with each other and with the auxiliary feed material (a2) in a melt mixing system.

7. The method according to any one of claims 1 to 6, wherein the main supply material (a1) is a combination of a1 st material and a2 nd material, the 1 st material being a molded body comprising 100 parts by mass of the (A) thermoplastic resin and 1 to 50 parts by mass of the (B) cellulose nanofibers, the 2 nd material being different in composition from the 1 st material.

8. The method of any one of claims 1 to 7, wherein the melt mixing is performed in the following proportions: the mixing ratio of the auxiliary feed material (a2) is 5 to 50 mass% with respect to 100 mass% of the total of the main feed material (a1) and the auxiliary feed material (a 2).

9. The method of any one of claims 1 to 8, wherein the melt mixing is melt kneading.

10. The method according to any one of claims 1 to 9, wherein the resin molded body is a pellet.

11. The method of claim 10, wherein said melt mixing is melt kneading, and said melt kneading and said molding are performed in a single mixer.

12. The method according to any one of claims 1 to 11, wherein the resin molded body has a molding shrinkage ratio TD/MD ratio of 1.05 to 3.0.

13. The method according to any one of claims 1 to 12, wherein the resin molded body has a mold shrinkage ratio of 0.2% to 1.2% in the MD direction and a mold shrinkage ratio of 0.5% to 1.2% in the TD direction.

14. The method according to any one of claims 1 to 13, wherein a TD/MD ratio (Rb) of the molding shrinkage rate of the resin molded body and a TD/MD ratio (Ra1) of the molding shrinkage rate of the comparative resin molded body satisfy the formula: [ Rb ] < [ Ra1], which is molded under the same conditions as the resin molded article except that molding is performed only with the main supply material (a1) in place of the resin composition (b).

15. The method according to any one of claims 1 to 14, wherein the tensile strength of the resin molded body is 90MPa or more.

16. The method according to any one of claims 1 to 15, wherein the elastic modulus of the main supply material (a1) and the elastic modulus of the resin composition (b) satisfy the following relationship:

[ elastic modulus of resin composition (b) ] ≧ elastic modulus of main feed material (a1) × 0.99.

17. The method of any one of claims 1 to 16,

the method further comprises a step of returning a part of the resin molded body as at least a part of the auxiliary supply material (a2) to the resin composition forming process, thereby causing the resin molded body to contain cellulose nanofibers subjected to the melting treatment of the main supply material (a1) and the resin composition forming process 2 or more times,

the ratio of the cellulose nanofibers subjected to the melting treatment of the main supply material (a1) and the resin composition forming step of 2 or more times is 20 mass% or less with respect to 100 mass% of the total amount of cellulose nanofibers in the resin molded product.

18. The method according to any one of claims 1 to 17, wherein a difference between a Yellowness (YI) value of the resin molded body and a Yellowness (YI) value of the auxiliary supply material is 10 or less.

19. The method according to any one of claims 1 to 18, wherein the thermoplastic resin (A) is a polyamide.

20. The method according to any one of claims 1 to 19, wherein the cellulose nanofibers (B) are modified cellulose nanofibers.

21. The method of claim 20, wherein the degree of substitution of the modified cellulose nanofibers is from 0.5 to 1.5.

Technical Field

The present invention relates to a method for producing a resin molded body containing a thermoplastic resin and cellulose nanofibers.

Background

Thermoplastic resins are lightweight and excellent in processability, and therefore are widely used in various fields such as automobile parts, electric and electronic parts, office equipment housings, and precision parts. However, a single resin is often insufficient in mechanical properties, slidability, thermal stability, dimensional stability, and the like, and a composite material of a resin and various inorganic materials is generally used.

A resin composition in which a thermoplastic resin is reinforced with a reinforcing material such as glass fiber, carbon fiber, talc, or clay as an inorganic filler has a high specific gravity, and therefore, has a problem that the weight of the obtained resin molded article increases. Therefore, in recent years, cellulose having a low environmental load has been used as a novel reinforcing material for resins.

Cellulose is known to have a high elastic modulus comparable to aramid fiber and a linear expansion coefficient lower than that of glass fiber as a characteristic of its simple substance. In addition, the density is low, 1.56g/cm³Glass (density 2.4 to 2.6 g/cm) generally used as a reinforcing material for thermoplastic resins³) Talc (density 2.7 g/cm)³) In contrast, it is an absolutely lightweight material.

The cellulose includes a plurality of branches such as cellulose made from hemp, cotton, kenaf, cassava, etc., in addition to cellulose made from trees. Bacterial cellulose typified by coconut is also known. These natural resources as cellulose raw materials are present in large quantities on earth, and in order to effectively utilize them, a technique of applying cellulose as a filler to a resin has been attracting attention.

CNF (cellulose nanofiber) is known to be obtained by using pulp or the like as a raw material, partially hydrolyzing hemicellulose to make it brittle, and then opening the hemicellulose by a pulverization method such as a high-pressure homogenizer, a high-pressure microjet homogenizer, a ball mill, or a disc pulverizer, and forms a highly dispersed state and a network in water in a fine level called nanodispersion.

In order to blend CNF into a resin, it is necessary to dry CNF into powder, but CNF changes from a micro-dispersed state to a firm aggregate in the process of separating from water, and has a problem of being difficult to redisperse. This cohesive force is expressed by hydrogen bonds generated by hydroxyl groups of cellulose, and is said to be very strong.

Therefore, in order to sufficiently exhibit the properties of CNF, it is necessary to relax hydrogen bonds generated by hydroxyl groups of cellulose. Even if hydrogen bonds can be alleviated, it is difficult to maintain the state of opening (nano-size (i.e., less than 1 μm)) in the resin.

Patent document 1 describes a fiber-reinforced resin composition containing (a) chemically modified cellulose nanofibers and (B) a thermoplastic resin, wherein the chemically modified cellulose nanofibers and the thermoplastic resin satisfy the following conditions: (a) (A) chemically modifying the dissolution parameter (SP) of cellulose nanofibers_cnf) Solubility Parameter (SP) relative to (B) thermoplastic resin_pol) Ratio of (S) R (SP)_cnf/SP_pol) In the range of 0.87 to 1.88; and (b) (A) the crystallinity of the chemically modified cellulose nanofiber is 42.7% or more.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-176052

Disclosure of Invention

Problems to be solved by the invention

The technique described in patent document 1 aims to provide a fiber-reinforced resin composition in which cellulose nanofibers are well dispersed by appropriately combining fibers having improved dispersibility with a resin that facilitates the dispersion of the fibers, and it is believed that the technique can improve the dispersibility of the cellulose nanofibers to some extent. But it has the following problems: when cellulose nanofibers are chemically and/or physically treated in order to improve the dispersibility of the cellulose nanofibers in the resin composition, the cellulose nanofibers are also deteriorated, and the reinforcing effect by the cellulose nanofibers cannot be sufficiently obtained.

On the other hand, cellulose nanofibers having a large fiber length have an excellent reinforcing effect, and when they are present in a resin composition, they can impart good mechanical strength to the resin composition. However, such cellulose nanofibers having a large fiber length are likely to be oriented in a resin composition, and therefore cause anisotropy (i.e., difference in physical properties depending on the direction) in physical properties (e.g., molding shrinkage and thermal expansion coefficient) of the resin composition. This anisotropy is known to be a factor of occurrence of warpage and the like when molding a large molded article.

As a means for suppressing such anisotropy, for example, cellulose nanofibers may be finely dispersed in a resin. In order to achieve such micro dispersion, for example, a method of imparting strong shear using a twin-screw extruder or a multi-screw extruder is generally employed. However, this method has a problem in recent years in that cellulose undergoes a strong thermal history to cause significant discoloration and a molded article having extremely significant coloration is provided. It is also known that a certain proportion of short paths are present in the processing by an extruder, and that sufficient dispersion cannot be obtained by simple kneading, and a composition in which huge agglomerates (specifically, a diameter of 5 μm or more, and sometimes several hundred μm or more) are mixed is formed. On the other hand, cellulose nanofibers subjected to strong shear may exhibit disadvantages such as a significant decrease in tensile strength and surface impact strength due to a decrease in fiber length.

Thus, a resin composition containing cellulose nanofibers which has good mechanical strength, is reduced in physical anisotropy and warpage, and is suppressed in coloring due to heat has not been obtained by the prior art.

An object of the present invention is to solve the above problems and to provide a method for producing a resin molded article, which can produce a resin molded article containing cellulose nanofibers, having good mechanical strength, having less anisotropy of physical properties and less warpage, and having suppressed coloring due to heat.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that the above problems can be solved by imparting a thermal history to cellulose nanofibers in a specific manner in the production of a resin molded article containing cellulose nanofibers, and have completed the present invention.

That is, the present invention includes the following aspects.

[1] A method for producing a resin molded body comprising (A) a thermoplastic resin and (B) a cellulose nanofiber, wherein the method comprises the steps of:

preparing a main supply material (a1) containing (a) a thermoplastic resin and (B) cellulose nanofibers, and an auxiliary supply material (a2) that is a melt-processed product of the main supply material (a 1);

a resin composition forming step of melt-mixing the main supply material (a1) and the auxiliary supply material (a2) to obtain a resin composition (b); and

and (c) molding the resin composition (b) to obtain a resin molded article.

[2] A method for improving the opening property of a cellulose nanofiber (B) in the production of a resin molded body comprising a thermoplastic resin (A) and a cellulose nanofiber (B), wherein the method comprises the steps of:

preparing a main supply material (a1) containing (a) a thermoplastic resin and (B) cellulose nanofibers, and an auxiliary supply material (a2) that is a melt-processed product of the main supply material (a 1);

a resin composition forming step of obtaining a resin composition (b) containing 2 or more types of cellulose nanofibers having different thermal histories by melt-mixing the main supply material (a1) and the auxiliary supply material (a 2); and

and (c) molding the resin composition (b) to obtain a resin molded article.

[3] The method according to mode 2 above, wherein the 2 or more types of cellulose nanofibers having different thermal histories have different fiber lengths from each other.

[4] The method according to any one of the above aspects 1 to 3, wherein a part of the resin molded body is used as the auxiliary supply material (a 2).

[5] The method according to any one of the above aspects 1 to 4, wherein the main supply material (a1) contains 100 parts by mass of the thermoplastic resin (A) and 1 to 50 parts by mass of the cellulose nanofibers (B).

[6] The method according to any one of the above aspects 1 to 5, wherein the constituent components of the main feed material (a1) are mixed with each other and with the auxiliary feed material (a2) in a melt-mixing system.

[7] The method according to any one of the above aspects 1 to 6, wherein the main supply material (a1) is a combination of a1 st material and a2 nd material, the 1 st material being a molded body comprising 100 parts by mass of the thermoplastic resin (a) and 1 to 50 parts by mass of the cellulose nanofibers (B), and the 2 nd material having a composition different from that of the 1 st material.

[8] The method according to any one of the above aspects 1 to 7, wherein the melt mixing is performed at the following ratio: the mixing ratio of the auxiliary supply material (a2) is 5 to 50 mass% with respect to 100 mass% of the total of the main supply material (a1) and the auxiliary supply material (a 2).

[9] The method according to any one of the above aspects 1 to 8, wherein the melt mixing is melt kneading.

[10] The method according to any one of embodiments 1 to 9, wherein the resin molded body is a pellet.

[11] The method according to mode 10 above, wherein the melt-mixing is melt-kneading, and the melt-kneading and the molding are performed in a single kneader.

[12] The method according to any one of the above aspects 1 to 11, wherein the resin molded body has a molding shrinkage ratio TD/MD ratio of 1.05 to 3.0.

[13] The method according to any one of embodiments 1 to 12, wherein the resin molded body has a molding shrinkage ratio in the MD of 0.2% to 1.2% and a molding shrinkage ratio in the TD of 0.5% to 1.2%.

[14] The method according to any one of embodiments 1 to 13, wherein the TD/MD ratio (Rb) of the molding shrinkage ratio of the resin molded body and the TD/MD ratio (Ra1) of the molding shrinkage ratio of the comparative resin molded body satisfy the following formula: [ Rb ] < [ Ra1], the comparative resin molded article was molded under the same conditions as the resin molded article except that the resin composition (b) was replaced with only the main supply material (a 1).

[15] The method according to any one of embodiments 1 to 14, wherein the tensile strength of the resin molded body is 90MPa or more.

[16] The method according to any one of embodiments 1 to 15, wherein the elastic modulus of the main supply material (a1) and the elastic modulus of the resin composition (b) satisfy a relationship of the following formula:

[ elastic modulus of resin composition (b) ] ≧ elastic modulus of main feed material (a1) × 0.99.

[17] The method according to any one of the above aspects 1 to 16, wherein,

the method further comprises a step of returning a part of the resin molded body as at least a part of the auxiliary supply material (a2) to the resin composition forming step, thereby allowing the resin molded body to contain the cellulose nanofibers subjected to the melting treatment of the main supply material (a1) and the resin composition forming step 2 or more times,

the ratio of the cellulose nanofibers subjected to the melting treatment of the main supply material (a1) and the resin composition forming step of 2 or more times is 20 mass% or less with respect to 100 mass% of the total amount of the cellulose nanofibers in the resin molded product.

[18] The method according to any one of the above aspects 1 to 17, wherein a difference between a Yellowness (YI) value of the resin molded body and a Yellowness (YI) value of the auxiliary supply material is 10 or less.

[19] The method according to any one of embodiments 1 to 18, wherein the thermoplastic resin (A) is polyamide.

[20] The method according to any one of the above aspects 1 to 19, wherein the cellulose nanofibers (B) are modified cellulose nanofibers.

[21] The method according to mode 20, wherein the degree of substitution of the modified cellulose nanofibers is 0.5 to 1.5.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a method for producing a resin molded body, which comprises cellulose nanofibers, has good mechanical strength, has little anisotropy of physical properties and warpage, and is suppressed in coloring due to heat.

Drawings

Fig. 1 is a diagram illustrating a process 100 as an example of a method for producing a resin molded body according to embodiment 1.

Fig. 2 is a diagram illustrating a process 200 as an example of the method for producing a resin molded body according to embodiment 1.

Fig. 3 is a diagram illustrating a process 300 as an example of the method for producing a resin molded body according to embodiment 1.

Fig. 4 is a diagram illustrating a process 400 as an example of the method for producing a resin molded body according to embodiment 2.

Detailed Description

The following describes exemplary embodiments of the present invention, but the present invention is not limited to these embodiments. In addition, elements given the same reference numerals in the drawings are intended to have the same configuration or function.

Production of resin molded article

One embodiment of the present invention provides a method for producing a resin molded body containing (a) a thermoplastic resin and (B) cellulose nanofibers. In one embodiment, the method comprises the steps of: a step of preparing a main supply material (a1) containing (a) a thermoplastic resin and (B) cellulose nanofibers, and an auxiliary supply material (a2) that is a melt-processed product of the main supply material (a 1); a resin composition forming step of melt-mixing the main supply material (a1) and the auxiliary supply material (a2) to obtain a resin composition (b); and a step of molding the resin composition (b) to obtain a resin molded article.

One embodiment of the present invention provides a method for improving the fiber opening property of (B) cellulose nanofibers in the production of a resin molded body comprising (a) a thermoplastic resin and (B) cellulose nanofibers. In one embodiment, the method comprises the steps of: preparing a main supply material containing (A) a thermoplastic resin and (B) cellulose nanofibers, and an auxiliary supply material that is a melt-processed product of the main supply material; a resin composition forming step of obtaining a resin composition containing 2 or more types of cellulose nanofibers having different thermal histories by melt-mixing the main supply material and the auxiliary supply material; and a step of molding the resin composition to obtain a resin molded article.

In one embodiment, the 2 or more types of cellulose nanofibers having different thermal histories have different fiber lengths from each other. For this reason, the fiber length of the cellulose nanofibers in the auxiliary feed material is shorter than the fiber length of the cellulose nanofibers in the main feed material.

In embodiment 1, the resin molded body is a molten mixture of the components of the main supply material (i.e., (a) the thermoplastic resin, (B) the cellulose nanofibers, and optionally additional components) and the auxiliary supply material. The resin molded body produced in embodiment 1 can be provided in the shape of pellets or the like as a representative.

In embodiment 2, the resin molded article is a molten mixture (1 st material) containing (a) a thermoplastic resin, (B) cellulose nanofibers, and optionally additional components, and a2 nd material having a different composition. In one embodiment, the 1 st material may be the resin molded body obtained in embodiment 1. The resin molded article produced in embodiment 2 can be provided in the shape of various molded products, typically in the shape of pellets or the like.

[ Components of the Main feed Material and the auxiliary feed Material ]

The main supply material (a1) may be in the form of a mixture containing (a) a thermoplastic resin, (B) cellulose nanofibers, and optionally additional components, or may be in the form of a mixture containing the components of the main supply material (i.e., the thermoplastic resin (a), the cellulose nanofibers (B), and optionally additional components). The auxiliary feed material is a melt processed product of the main feed material. Therefore, the sub-supply material and the main supply material have substantially the same composition (i.e., the same types and amounts of the constituent components), but at least a part of the constituent components of the main supply material may be denatured by the melting process. The denaturation comprises (B) a reduction in fiber length of the cellulose nanofibers.

The auxiliary feed material (a2) has substantially the same composition as the main feed material, and therefore is very well mixed with the feed material. In addition, in the auxiliary supply material, the fiber length of the cellulose nanofibers in the main supply material is reduced, and therefore, in the mixture of the main supply material and the auxiliary supply material, the cellulose nanofibers originating from the main supply material (i.e., having a relatively large fiber length) and the cellulose nanofibers originating from the auxiliary supply material (i.e., having a relatively small fiber length) are mixed. When the fiber length of the cellulose nanofibers is increased, the mechanical strength of the resin molded product is improved, but on the other hand, the fluidity of the resin composition at the time of producing the resin molded product is lowered, so that the dispersibility of the cellulose nanofibers in the resin molded product is lowered, and the anisotropy of the physical properties (for example, the thermal expansion coefficient) of the resin molded product (for example, the difference between the directions corresponding to the MD direction and the TD direction at the time of producing the resin molded product) tends to be increased. Since the presence of cellulose nanofibers having a large fiber length has a particularly large influence on the mechanical strength, the mechanical strength can be significantly improved even if the cellulose nanofibers having a large fiber length are used in a smaller amount. On the other hand, the presence of cellulose nanofibers having a large fiber length does not significantly affect the anisotropy and dispersibility of physical properties as compared with the case of mechanical strength. Therefore, in the case of a resin molded product obtained by using a mixture of the main supply material and the auxiliary supply material, the mechanical strength significantly contributed by the presence of the cellulose nanofibers having a large fiber length is good, and the effects of the reduction in the anisotropy of physical properties and the improvement in the dispersibility due to the coexistence of the cellulose nanofibers having a reduced fiber length are also obtained well. Thus, the resin molded article obtained by the method of the present disclosure can have the advantage of satisfying both of the specificity of good mechanical strength, good dispersibility, and less anisotropy. In addition, the auxiliary feed material is cracked at the weakest point in the structure, specifically, in the cellulose nanofiber aggregate present in the structure due to the shear to which it is subjected during melting, with the result that the cellulose nanofiber aggregate becomes finer, and also exhibits a synergistic effect of an increase in the viscosity of the system, enabling a significant reduction in the amount of cellulose nanofiber aggregate that may be contained in the final molded body.

In one embodiment, the auxiliary supply material may be taken out from a part of the resin molded body and returned to the process. As the auxiliary supply material, for example, from the viewpoint of economy, the following materials can be used within a range in which no problem occurs: (1) a resin molded body obtained after production is started and before process conditions are stabilized, in order to obtain a target resin molded body; (2) a resin molded body having substantially the same composition but exhibiting physical properties different from those of the objective resin molded body; (3) a resin molded body having substantially the same composition as that of the objective resin molded body in the resin molded body obtained in the transition time zone during the composition change process; and so on. The term "substantially the same composition" as used herein means that the amount of each component constituting the resin molded article is within the range of + 5% by mass to-5% by mass. Specifically, for example, when the content of the cellulose nanofibers (B) is 7.5 mass%, the composition is substantially the same, which means that the composition is in the range of 7.125 to 7.875 mass%. The range of + 5% to-5% is approximately the same as the fluctuation of the composition caused when a material is periodically added (re-added) to a material supply device provided in the kneading machine.

In one embodiment, the amount of the (B) cellulose nanofibers in the main supply material is preferably 1 mass% or more, more preferably 3 mass% or more, and even more preferably 5 mass% or more, from the viewpoint of obtaining a good moldability and dispersibility, and from the viewpoint of reducing anisotropy, from the viewpoint of obtaining a good property-improving effect (for example, an improving effect on mechanical strength, thermal stability, durability, and the like) by the (B) cellulose nanofibers, and is preferably 50 mass% or less, more preferably 40 mass% or less, and even more preferably 20 mass% or less.

An exemplary mode of the constituent elements of the main supply material (and the auxiliary supply material having substantially the same composition as the main supply material) will be further described below.

[ thermoplastic resin (A) ]

As the thermoplastic resin (a), various resins can be used. In one embodiment, (a) the thermoplastic resin has a number average molecular weight of 5000 or more. The number average molecular weight of the present disclosure is a value obtained by converting a spectrum obtained by measurement using GPC (gel permeation chromatography) into a standard polymer for GPC. As the standard polymer for GPC in this case, a polymer known to those skilled in the art can be used. Polystyrene, polymethyl methacrylate, polyethylene glycol, polyoxyethylene, and the like are generally exemplified. Which standard polymer is used is selected according to the kind of the eluent at the time of GPC measurement. For example, when hexafluoroisopropanol is used as the eluent, polymethyl methacrylate is used as the standard polymer; when the eluent is tetrahydrofuran, chloroform, toluene and 1,2, 4-trichlorobenzene, the standard polymer is polystyrene; when the eluent is methanol, N-dimethylformamide or water system, polyethylene glycol or polyoxyethylene is used as the standard polymer.

Examples of the thermoplastic resin (A) include a crystalline resin having a melting point in the range of 100 to 350 ℃ and an amorphous resin having a glass transition temperature in the range of 100 to 250 ℃. (A) The thermoplastic resin may be composed of 1 or 2 or more kinds of polymers of either homopolymers or copolymers.

The melting point of the crystalline resin as used herein means the peak top temperature of an endothermic peak which appears when the temperature is raised from 23 ℃ at a temperature raising rate of 10 ℃/minute using a Differential Scanning Calorimeter (DSC). When 2 or more endothermic peaks appear, the peak top temperature of the endothermic peak on the highest temperature side is referred to. The enthalpy value of the endothermic peak at this time is preferably 10J/g or more, more preferably 20J/g or more. In addition, in the measurement, it is preferable to use a sample obtained as follows: the sample was heated at once to a temperature of not less than the melting point +20 ℃ to melt the resin, and then cooled to 23 ℃ at a cooling rate of 10 ℃/min, and the obtained sample was used.

The glass transition temperature of the amorphous resin as referred to herein is a peak top temperature at which the storage modulus is significantly lowered and the loss modulus reaches a maximum peak when measured at an application frequency of 10Hz while the temperature is raised from 23 ℃ at a temperature rise rate of 2 ℃/minute using a dynamic viscoelasticity measuring apparatus. When 2 or more loss modulus peaks appear, the peak top temperature refers to the peak on the highest temperature side. In order to improve the measurement accuracy, the measurement frequency is preferably measured at least 1 time in at least 20 seconds. The method for preparing the sample for measurement is not particularly limited, but a cut piece of a hot press molded product is preferably used in terms of eliminating the influence of molding strain, and the size (width and thickness) of the cut piece is preferably reduced as much as possible in terms of heat conduction.

Examples of the thermoplastic resin (a) include polyamide resins, polyester resins, polyacetal resins, polycarbonate resins, polyacrylic resins, polyphenylene ether resins (including modified polyphenylene ethers obtained by blending polyphenylene ethers with other resins or by graft polymerization), polyarylate resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, polyketone resins, polyphenylene ether ketone resins, polyimide resins, polyamideimide resins, polyetherimide resins, polyurethane resins, polyolefin resins (for example, α -olefin (co) polymers), and various ionomers.

These components may be used singly or in combination of two or more. When two or more kinds are used in combination, the polymer alloy may be used. The thermoplastic resin may be modified with at least one compound selected from unsaturated carboxylic acids, anhydrides thereof, and derivatives thereof.

Among these, from the viewpoint of heat resistance, moldability, aesthetic properties and mechanical properties, 1 or more resins selected from the group consisting of polyolefin-based resins, polyamide-based resins, polyester-based resins, polyacetal-based resins, polyacrylic-based resins, polyphenylene ether-based resins and polyphenylene sulfide-based resins are preferable.

Among these, from the viewpoint of handling properties and cost, more preferable are 1 or more resins selected from the group consisting of polyolefin-based resins, polyamide-based resins, polyacetal-based resins, and polyphenylene ether-based resins, and particularly preferable are 1 or more resins selected from the group consisting of polyolefin-based resins and polyamide-based resins. In a particularly preferred embodiment, the thermoplastic resin (a) is a polyamide.

The polyolefin resin is a polymer obtained by polymerizing monomer units including olefins (for example, α -olefins). Specific examples of the polyolefin-based resin are not particularly limited, and examples thereof include ethylene-based (co) polymers exemplified by low-density polyethylene (e.g., linear low-density polyethylene), high-density polyethylene, ultra-low-density polyethylene, ultra-high-molecular-weight polyethylene, polypropylene-based (co) polymers exemplified by polypropylene, ethylene-propylene copolymers, ethylene-propylene-diene copolymers, and copolymers of α -olefins represented by ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-glycidyl methacrylate copolymers, and other monomer units.

The most preferred polyolefin resin herein is polypropylene. In particular, polypropylene having a Melt Flow Rate (MFR) of 3g/10 min to 30g/10 min as measured at 230 ℃ under a load of 21.2N in accordance with ISO1133 is preferred. The lower limit of MFR is more preferably 5g/10 min, still more preferably 6g/10 min, and most preferably 8g/10 min. The upper limit is more preferably 25g/10 min, still more preferably 20g/10 min, and most preferably 18g/10 min. The MFR is preferably not more than the upper limit value in view of improving the toughness of the composition, and the MFR is preferably not less than the lower limit value in view of the flowability of the composition.

In addition, in order to improve the affinity with cellulose, a polyolefin resin modified with an acid may be suitably used. The acid can be suitably selected from maleic acid, fumaric acid, succinic acid, phthalic acid, anhydrides thereof, and polycarboxylic acids such as citric acid. Among these, maleic acid or an anhydride thereof is preferable in terms of easiness of improvement of the modification rate. The modification method is not particularly limited, and generally, the resin is heated to a temperature not lower than the melting point in the presence/absence of a peroxide to be melt-kneaded. As the polyolefin resin to be acid-modified, any of the above polyolefin resins can be used, and among them, polypropylene can be suitably used.

The acid-modified polyolefin resin may be used alone, but is more preferably used in combination with an unmodified polyolefin resin in order to adjust the modification ratio of the composition. For example, in the case of using a mixture of unmodified polypropylene and acid-modified polypropylene, the proportion of the acid-modified polypropylene to the entire polypropylene is preferably 0.5 to 50% by mass. The lower limit is more preferably 1% by mass, still more preferably 2% by mass, even more preferably 3% by mass, particularly preferably 4% by mass, and most preferably 5% by mass. The upper limit is more preferably 45% by mass, still more preferably 40% by mass, even more preferably 35% by mass, particularly preferably 30% by mass, and most preferably 20% by mass. In order to maintain the interfacial strength with cellulose, the lower limit or more is preferable; the upper limit or less is preferable for maintaining the ductility as a resin.

The lower limit of the acid modification rate of the acid-modified polyolefin resin is preferably 0.01 mass%, more preferably 0.1 mass%, even more preferably 0.3 mass%, particularly preferably 0.5 mass%, and most preferably 0.7 mass%. The upper limit is preferably 10% by mass, more preferably 5% by mass, even more preferably 3% by mass, particularly preferably 2% by mass, and most preferably 1.5% by mass. The lower limit or more is preferable for maintaining the interface strength with cellulose, and the upper limit or less is preferable for maintaining the mechanical properties of the acid-modified polyolefin.

In order to improve the affinity with the cellulose interface, it is preferred that the acid-modified polypropylene has a Melt Flow Rate (MFR) of preferably 50g/10 min or more as measured at 230 ℃ under a load of 21.2N in accordance with ISO 1133. The lower limit is more preferably 100g/10 min, still more preferably 150g/10 min, and most preferably 200g/10 min. The upper limit is not particularly limited, and is 500g/10 min in view of maintaining the mechanical strength. By setting the MFR within this range, an advantage of being easily present at the interface between the cellulose and the resin can be enjoyed.

The polyamide resin preferable as the thermoplastic resin is not particularly limited, and examples thereof include: polyamide 6, polyamide 11, polyamide 12, and the like obtained by polycondensation of lactams; polyamide 6 obtained as a copolymer of diamines such as 1, 6-hexamethylenediamine, 2-methyl-1, 5-pentanediamine, 1, 7-heptanediamine, 2-methyl-1-6-hexamethylenediamine, 1, 8-octanediamine, 2-methyl-1, 7-heptanediamine, 1, 9-nonanediamine, 2-methyl-1, 8-octanediamine, 1, 10-decanediamine, 1, 11-undecanediamine, 1, 12-dodecanediamine and m-xylylenediamine with dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, benzene-1, 2-dicarboxylic acid, benzene-1, 3-dicarboxylic acid and benzene-1, 4-dicarboxylic acid, and dicarboxylic acids such as cyclohexane-1, 3-dicarboxylic acid and cyclohexane-1, 4-dicarboxylic acid, 6. polyamide 6,10, polyamide 6,11, polyamide 6,12, polyamide 6, T, polyamide 6, I, polyamide 9, T, polyamide 10, T, polyamide 2M5, T, polyamide MXD,6, polyamide 6, C, polyamide 2M5, C, etc.; and copolymers such as copolymers obtained by copolymerizing these monomers (for example, polyamide 6, T/6, I).

Among these polyamide resins, aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 6, polyamide 6,10, polyamide 6,11 and polyamide 6,12, and alicyclic polyamides such as polyamide 6, C and polyamide 2M5, C are more preferable.

The concentration of the terminal carboxyl group of the polyamide resin is not particularly limited, and the lower limit is preferably 20. mu. mol/g, more preferably 30. mu. mol/g. The upper limit of the concentration of the terminal carboxyl group is preferably 150. mu. mol/g, more preferably 100. mu. mol/g, and still more preferably 80. mu. mol/g.

In the polyamide resin, the ratio of carboxyl end groups to all end groups ([ COOH ]/[ all end groups ]) is preferably 0.30 to 0.95. The lower limit of the carboxyl end group ratio is more preferably 0.35, still more preferably 0.40, and most preferably 0.45. The upper limit of the carboxyl end group ratio is more preferably 0.90, still more preferably 0.85, and most preferably 0.80. The carboxyl end group ratio is preferably 0.30 or more in view of dispersibility of the cellulose nanofibers (B) in the resin composition, and is preferably 0.95 or less in view of color tone of the obtained resin composition.

As a method for adjusting the terminal group concentration of the polyamide resin, a known method can be used. For example, a method of adding a terminal group adjusting agent which reacts with a terminal group such as a diamine compound, a monoamine compound, a dicarboxylic acid compound, a monocarboxylic acid compound, an acid anhydride, a monoisocyanate, a monohalide, a monoester, or a monoalcohol to a polymerization solution so as to obtain a predetermined terminal group concentration at the time of polymerizing a polyamide is mentioned.

Examples of the terminal-adjusting agent which reacts with the terminal amino group include: aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, tetradecanoic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, methylbenzoic acid, α -naphthoic acid, β -naphthoic acid, methylnaphthoic acid, and phenylacetic acid; and mixtures of 2 or more selected from these substances. Among these, from the viewpoints of reactivity, stability of blocked ends, price, and the like, 1 or more kinds of end-point-modifying agents selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid are preferable, and acetic acid is most preferable.

Examples of the terminal-adjusting agent which reacts with the terminal carboxyl group include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine and the like; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine and naphthylamine; and any mixtures thereof. Among these, 1 or more terminal regulators selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline are preferable from the viewpoints of reactivity, boiling point, stability of blocked terminals, price, and the like.

From the viewpoint of accuracy and simplicity, the concentration of the amino terminal group and the carboxyl terminal group is preferably determined by¹H-NMR was obtained from the integral value of the characteristic signal corresponding to each terminal group. As a method for obtaining the concentration of these terminal groups, a method described in Japanese patent application laid-open No. 7-228775 is specifically proposed. In the case of using this method, deuterated trifluoroacetic acid is useful as a measurement solvent. In addition, the following are¹The number of H-NMR integrations also required at least 300 scans when measured with equipment with sufficient resolution. The concentration of the terminal group can also be measured by a titration-based measurement method described in Japanese patent application laid-open No. 2003-055549. However, in order to reduce the influence of additives, lubricants and the like to be mixed as much as possible, it is more preferable to use¹H-NMR was used for the quantification.

The polyamide resin preferably has a viscosity number [ VN ] of 60 to 300, more preferably 70 to 250, still more preferably 75 to 200, and particularly preferably 80 to 180, as measured in 96% sulfuric acid in accordance with ISO 307. The polyamide resin having a viscosity number in the above range is advantageous in that the resin composition can exhibit good in-mold flowability in the production of a resin molded article by injection molding, and the resin molded article can exhibit good appearance.

The polyester resin preferable as the thermoplastic resin is not particularly limited, and 1 or 2 or more selected from polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene succinate (PBS), polybutylene succinate-adipate (PBSA), polybutylene terephthalate-adipate (PBAT), Polyarylate (PAR), polyhydroxyalkanoic acid (PHA) (a polyester resin formed of 3-hydroxyalkanoic acid), polylactic acid (PLA), Polycarbonate (PC), and the like can be used. Among these, PET, PBS, PBSA, PBT and PEN are more preferable, and PBS, PBSA and PBT are still more preferable.

In the polyester resin, the terminal group may be changed depending on the monomer ratio during polymerization and the presence or absence of addition and the amount of addition of the terminal stabilizer, but the ratio of the carboxyl terminal group to the total terminal groups ([ COOH ]/[ total terminal groups ]) of the polyester resin is preferably 0.30 to 0.95. The lower limit of the proportion of the carboxyl end groups is more preferably 0.35, still more preferably 0.40, and most preferably 0.45. The upper limit of the ratio of the carboxyl terminal group is more preferably 0.90, still more preferably 0.85, and most preferably 0.80. The proportion of the carboxyl end groups is preferably 0.30 or more in view of dispersibility of the cellulose nanofibers (B) in the composition, and is preferably 0.95 or less in view of color tone of the resulting composition.

The polyacetal resin preferable as the thermoplastic resin is usually homo-acetal using formaldehyde as a raw material and co-acetal using trioxymethylene as a main monomer (for example, containing 1, 3-dioxolane as a comonomer component), and both of them can be used, but from the viewpoint of thermal stability at the time of processing, co-acetal can be preferably used. In particular, the amount of the comonomer component (e.g., 1, 3-dioxolane) is preferably in the range of 0.01 to 4 mol%. The lower limit amount of the comonomer component is more preferably 0.05 mol%, still more preferably 0.1 mol%, and particularly preferably 0.2 mol%. The upper limit amount is more preferably 3.5 mol%, still more preferably 3.0 mol%, particularly preferably 2.5 mol%, and most preferably 2.3 mol%. The lower limit is preferably within the above range from the viewpoint of thermal stability during extrusion processing and molding processing, and the upper limit is preferably within the above range from the viewpoint of mechanical strength.

< cellulose nanofiber (B) >

(B) The cellulose nanofibers are cellulose having an average fiber diameter of 1000nm or less. (B) Preferable examples of the cellulose nanofibers are not particularly limited, and for example, 1 or more kinds of cellulose nanofibers produced from cellulose pulp or modified products of these celluloses can be used. Among these, 1 or more modified products of cellulose can be preferably used from the viewpoint of stability, performance, and the like. The cellulose nanofibers (B) have an average fiber diameter of 1000nm or less, preferably 500nm or less, and more preferably 200nm or less, from the viewpoint of obtaining a good mechanical strength (particularly tensile elastic modulus) of the resin molded article. The average fiber diameter is preferably small, but from the viewpoint of ease of processing, it may be preferably 10nm or more, more preferably 20nm or more, and still more preferably 30nm or more. The average fiber diameter is a value determined as a sphere-equivalent diameter (volume average particle diameter) of particles when an integrated volume reaches 50% by a laser diffraction/scattering method particle size distribution.

The average fiber diameter can be measured by the following method. Cellulose nanofibers (B) were used as a solid content of 40 mass%, and the resulting mixture was kneaded in a planetary mixer (e.g., a kneader (manufactured by Kagaku corporation, 5 DM-03-R) with a stirring blade of a hook Type) at 126rpm for 30 minutes at room temperature and normal pressure, then prepared into a pure water suspension at a concentration of 0.5 mass%, dispersed at 15,000rpm × 5 minutes using a high shear HOMOGENIZER (e.g., a processing condition of "EXCEL AUTO HOMENIZER ED-7" manufactured by Nippon Seiko Co., Ltd.), and centrifuged at 39200m by using a centrifugal separator (e.g., a centrifugal separator of "6800 Type" manufactured by Kubota Seisakusho Co., Ltd., product, Rotor Type RA-400 Type)²Centrifugation was carried out for 10 minutes under the treatment conditions of/s, and the supernatant was collected and further processed at 116000m²Centrifugation was carried out for 45 minutes at/s, and the centrifuged supernatant was collected. The supernatant was used to obtain a volume-frequency particle size distribution by laser diffraction/scattering method (for example, horiba, trade name "LA-910" or trade name "LA-950", ultrasonic treatment for 1 minute, refractive index 1.20) in which the integral of the 50% particle diameter (that is, the integral volume of the particle volume relative to the volume of the whole particle is expressed asSphere-reduced diameter of particles to 50%) as a volume average particle diameter.

In a typical embodiment, the L/D ratio of the cellulose nanofibers (B) is 20 or more. The lower limit of L/D of the cellulose nanofibers is preferably 30, more preferably 40, further preferably 50, and further more preferably 100. The upper limit is not particularly limited, and is preferably 10000 or less from the viewpoint of handling property. In order to exert good mechanical properties of the resin composition of the present disclosure with a small amount of cellulose nanofibers, the L/D ratio of the cellulose nanofibers is preferably within the above range.

In the present disclosure, the length (L), diameter (D), and L/D ratio of the cellulose nanofibers are determined as follows: the measurement sample is obtained by dispersing an aqueous dispersion of cellulose nanofibers using a high shear HOMOGENIZER (for example, product of japan precision co., ltd., trade name "EXCEL AUTO homo determination ED-7") at a rotation speed of 15,000rpm × 5 minutes, diluting the obtained aqueous dispersion with pure water to 0.1 to 0.5 mass%, casting it on mica, air-drying it, and measuring it with an optical microscope, a high resolution scanning microscope (SEM), or an Atomic Force Microscope (AFM). Specifically, in an observation field in which magnification adjustment is performed so that at least 100 cellulose nanofibers are observed, the length (L) and the diameter (D) of 100 randomly selected cellulose nanofibers are measured, and the ratio (L/D) is calculated. In addition, the length and diameter of the cellulose nanofibers of the present disclosure are the number average of the above 100 celluloses.

(B) The cellulose nanofibers may be cellulose obtained as follows: pulp and the like are treated with hot water or the like at 100 ℃ or higher to partially hydrolyze and embrittle hemicellulose, and then the hemicellulose is opened by a pulverization method using a high-pressure homogenizer, a high-pressure microjet homogenizer, a ball mill, a disc pulverizer, or the like to obtain cellulose.

In one embodiment, (B) the cellulose nanofibers are modified (i.e., modified cellulose nanofibers). Examples of the modified cellulose nanofibers (B) include those obtained by modifying cellulose with at least 1 kind of modifying agent selected from the group consisting of an esterifying agent, a silylating agent, an isocyanate compound, a haloalkylating agent, an oxyalkylene compound and/or a glycidyl compound. In a preferred embodiment, (B) the cellulose nanofibers are unmodified or modified so as not to contain an oxoacid-modifying group (i.e., a site where a hydroxyl group of the cellulose is converted by an oxoacid (e.g., carboxylic acid) or a salt thereof (e.g., carboxylate salt)), and examples of the preferred modified cellulose fibers include those obtained by using the above-mentioned modifying agents.

The esterifying agent as the modifier contains an organic compound having at least one functional group capable of reacting with and esterifying the hydroxyl groups of the surface of the (B) cellulose nanofibers. The esterification can be carried out by the method described in paragraph [0108] of International publication No. 2017/159823. The esterification agent may be a commercially available reagent or product.

Suitable examples of the esterification agent are not particularly limited, and examples thereof include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, tetradecanoic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, methylbenzoic acid, α -naphthoic acid, β -naphthoic acid, methylnaphthoic acid, and phenylacetic acid; and optionally 2 or more kinds of mixtures thereof and esters of these acids with vinyl alcohol (for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl caproate, vinyl caprylate, vinyl laurate, etc.), and optionally symmetric anhydrides (for example, acetic anhydride, maleic anhydride, cyclohexane-carboxylic anhydride, benzene-sulfonic anhydride), mixed anhydrides (for example, butyric-valeric anhydride), cyclic acid anhydrides (for example, succinic anhydride, phthalic anhydride, naphthalene-1, 8:4, 5-tetracarboxylic dianhydride, cyclohexane-1, 2,3, 4-tetracarboxylic acid 3, 4-anhydride), ester acid anhydrides (for example, acetic acid 3- (ethoxycarbonyl) propane anhydride, benzoylethyl carbonate), and the like.

Among these, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, esters of these acids with vinyl alcohol, benzoic acid, acetic anhydride, maleic anhydride, succinic anhydride, and phthalic anhydride can be preferably used from the viewpoints of reactivity, stability, price, and the like.

The silylating agent as the modifier comprises a Si-containing compound having at least one reactive group capable of reacting with a hydroxyl group on the surface of the cellulose or a hydrolyzed group thereof. The silylating agent may be a commercially available reagent or product.

Preferred examples of the silylating agent are not particularly limited, and examples thereof include dimethylisopropylchlorosilane, dimethylbutylchlorosilane, dimethyloctylchlorosilane, dimethyldodecylchlorosilane, dimethyloctadecylchlorosilane, dimethylphenylchlorosilane, (1-hexenyl) dimethylchlorosilane, hexylmethyldichlorosilane, heptylmethyldichlorosilane, octyltrichlorosilane, hexamethyldisilazane, 1, 3-divinyl-1, 1,3, 3-tetramethyldisilazane, 1, 3-divinyl-1, 3-diphenyl-1, 3-dimethyl-disilazane, 1, 3-N-dioctyltetramethyldisilazane, diisobutytetramethyldisilazane, diethyltetramethyldisilazane, N-dipropyltetramethyldisilazane, N-propyldimethyldisilazane, and the like, N-dibutyltetramethyldisilazane or 1, 3-bis (p-t-butylethylethyl) tetramethyldisilazane, N-trimethylsilylacetamide, N-methyldiphenylsilylacetamide, N-triethylsilylacetamide, t-butyldiphenylmethoxysilane, octadecyldimethylmethoxysilane, dimethyloctylmethoxysilane, octylmethyldimethoxysilane, octyltrimethoxysilane, trimethylethoxysilane, octyltriethoxysilane, etc.

Among these, hexamethyldisilazane, octadecyldimethylmethoxysilane, dimethyloctylmethoxysilane, and trimethylethoxysilane can be preferably used from the viewpoints of reactivity, stability, price, and the like.

The haloalkylating agent as the modifier contains an organic compound having at least one functional group capable of reacting with a hydroxyl group on the surface of the cellulose to haloalkylate the same. The haloalkylating agent may be a commercially available reagent or product.

Preferred examples of the haloalkylating agent are not particularly limited, and chloropropane, chlorobutane, bromopropane, bromohexane, bromoheptane, iodomethane, iodoethane, iodooctane, iodooctadecane, iodobenzene, and the like can be used. Among these, bromohexane and iodooctane can be preferably used from the viewpoints of reactivity, stability, price, and the like.

The isocyanate compound as the modifier contains an organic compound having at least one isocyanate group capable of reacting with the hydroxyl group on the surface of the cellulose nanofiber (B). The isocyanate compound may be a blocked isocyanate compound which can be regenerated into an isocyanate group by releasing a blocked group at a specific temperature, or may be a modified product such as a dimer or trimer of a polyisocyanate or biuretized isocyanate, or polymethylene polyphenyl polyisocyanate (polymeric MDI). They may be reagents or products which are commercially available.

Preferred examples of the isocyanate compound are not particularly limited, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, araliphatic polyisocyanates, blocked isocyanate compounds, and polyisocyanates. Examples thereof include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2,4, 4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1, 5-diisocyanate, 3-methylpentane-1, 5-diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4 ' -dicyclohexylmethane diisocyanate, 1, 4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1, 3-bis (isocyanotomethyl) cyclohexane), Tolylene Diisocyanate (TDI), 2 ' -diphenylmethane diisocyanate, 2,4 ' -diphenylmethane diisocyanate, hexamethylene diisocyanate, and the like, 4,4 '-diphenylmethane diisocyanate (MDI), 4' -dibenzyl diisocyanate, 1, 5-naphthylene diisocyanate, xylylene diisocyanate, 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate), dialkyl diphenylmethane diisocyanate, tetraalkyl diphenylmethane diisocyanate, α, α -tetramethylxylylene diisocyanate, a blocked isocyanate compound obtained by reacting an oxime-based blocking agent, a phenol-based blocking agent, a lactam-based blocking agent, an alcohol-based blocking agent, an active methylene-based blocking agent, an amine-based blocking agent, a pyrazole-based blocking agent, a bisulfite-based blocking agent, or an imidazole-based blocking agent with the above isocyanate compound, and the like.

Among these, TDI, MDI, hexamethylene diisocyanate, and blocked isocyanates using a modified hexamethylene diisocyanate and hexamethylene diisocyanate as raw materials can be preferably used from the viewpoints of reactivity, stability, price, and the like.

From the viewpoints of reactivity and stability, the upper limit of the dissociation temperature of the blocking group of the blocked isocyanate compound is preferably 210 ℃, more preferably 190 ℃, and still more preferably 150 ℃. The lower limit is preferably 70 ℃, more preferably 80 ℃, and still more preferably 110 ℃. Examples of the blocking agent having a dissociation temperature of the blocking group within this range include methyl ethyl ketoxime, o-sec-butyl phenol, caprolactam, sodium hydrogen sulfite, 3, 5-dimethylpyrazole, and 2-methylimidazole.

The oxyalkylene and/or glycidyl compounds as modifiers comprise organic compounds having at least one oxyalkylene, glycidyl and/or epoxy group capable of reacting with hydroxyl groups on the cellulose surface. The oxyalkylene and/or glycidyl compounds may be commercially available reagents or products.

Preferred examples of the oxyalkylene and/or glycidyl compounds are not particularly limited, and include, for example: glycidyl ethers such as methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, 2-methyloctyl glycidyl ether, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether, n-butylphenyl glycidyl ether, phenylphenol glycidyl ether, tolyl glycidyl ether, and dibromotolyl glycidyl ether; glycidyl esters such as glycidyl acetate and glycidyl stearate; polyhydric alcohol glycidyl ethers such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1, 4-butanediol diglycidyl ether, hexamethylene glycol diglycidyl ether, resorcinol diglycidyl ether, bisphenol a diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polybutylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, sorbitol polyglycidyl ether, sorbitol anhydride polyglycidyl ether, polyglycerol polyglycidyl ether, and diglycerol polyglycidyl ether.

Among these, 2-methyloctyl glycidyl ether, hexamethylene glycol diglycidyl ether, and pentaerythritol tetraglycidyl ether can be preferably used from the viewpoints of reactivity, stability, price, and the like.

The total substitution degree of the modified cellulose nanofibers is 0.5 or more, or 0.7 or more, or 0.75 or more, from the viewpoint of obtaining good dispersibility of the (B) cellulose nanofibers in the (a) thermoplastic resin, and the total substitution degree of the modified cellulose nanofibers is 1.5 or less, or 1.3 or less, or 1.25 or less, from the viewpoint of maintaining the physical properties of the (B) cellulose nanofibers well. In one embodiment, the modified cellulose nanofibers are esterified cellulose nanofibers, and the total degree of substitution is a total degree of ester substitution. The degree of substitution can be determined as follows: freezing and crushing the modified cellulose nano-fiber¹³C solid-state NMR measurement was carried out, and the degree of substitution was determined from the following formula based on the area intensity (Inf) of a signal ascribed to one carbon atom of the modifying group, relative to the total area intensity (Inp) of signals ascribed to C1-C6 of a pyranose ring derived from cellulose, which occurred in the range of 50ppm to 110 ppm.

Degree of substitution ═ Inf. times.6/(Inp)

For example, in the case where the modifying group is acetyl, the group assigned to-CH is used₃The signal of 23 ppm.

The following illustrates the use¹³Conditions for C solid NMR measurement.

The device comprises the following steps: bruker Biospin Avance500WB

Frequency: 125.77MHz

A method of measurement; DD/MAS process

Waiting time: 75sec

NMR sample tube: 4mm phi

Integration times: 640 times (about 14Hr)

MAS：14,500Hz

Chemical shift standard: glycine (external reference: 176.03ppm)

Supplement component

The main supply material may optionally contain additional components in addition to the thermoplastic resin (a) and the cellulose nanofibers (B). Examples of the additional component include a surface treatment agent, an antioxidant, an inorganic filler, and a lubricating oil. These components may be used in combination of 1 or 2 or more, respectively. In addition, these components may be reagents or products that are commercially available.

Preferable examples of the surface treatment agent include compounds having a hydrophilic segment and a hydrophobic segment in the molecule, and more specifically, copolymers (for example, a block copolymer of propylene oxide and ethylene oxide, a block copolymer of tetrahydrofuran and ethylene oxide) obtained by using one or more compounds providing a hydrophilic segment (for example, polyethylene glycol), compounds providing a hydrophobic segment (for example, polypropylene glycol, poly (tetramethylene ether) glycol (PTMEG), polybutadiene glycol, and the like), and the like.

The preferable content of the surface treatment agent in the main supply material is preferably 0.1 mass% or more, or 0.2 mass% or more, or 0.5 mass% from the viewpoint of improving the dispersibility of the cellulose nanofibers in the resin molded product (B), and is preferably 50 mass% or less, or an upper limit of 30 mass%, or 20 mass%, or 18 mass%, or 15 mass%, or 10 mass%, or 5 mass% from the viewpoint of suppressing the plasticization of the resin molded product and maintaining the strength well.

The preferable amount of the surface treatment agent to 100 parts by mass of the (B) cellulose nanofibers is preferably 0.1 part by mass or more, or 0.5 part by mass or more, or 1 part by mass or more from the viewpoint of improving the dispersibility of the (B) cellulose nanofibers in the resin molded product, and is preferably 100 parts by mass or less, or 99 parts by mass or less, or 90 parts by mass or less, or 80 parts by mass or less, or 70 parts by mass or less, or 50 parts by mass or less, or 40 parts by mass or less from the viewpoint of suppressing the plasticization of the resin molded product and maintaining the strength well.

As the antioxidant, from the viewpoint of the effect of preventing deterioration due to heat, a hindered phenol-based antioxidant, a sulfur-based antioxidant, and a phosphorus-based antioxidant are preferable, a phosphorus-based antioxidant and a hindered phenol-based antioxidant are more preferable, and a combination of a phosphorus-based antioxidant and/or a hindered phenol-based antioxidant and a hindered amine-based light stabilizer (HALS) is further preferable.

The preferable amount of the antioxidant is preferably 0.01% by mass or more, or 0.02% by mass or more, or 0.03% by mass or more, or 0.05% by mass or more, and preferably 5% by mass or less, or 4% by mass or less, or 3% by mass or less, or 2% by mass or less, or 1% by mass or less with respect to the whole resin molded body.

Examples of the inorganic filler include fibrous particles, plate-like particles, and inorganic pigments. The fibrous particles and the plate-like particles may have an average aspect ratio of 5 or more. Specific examples thereof include glass fibers, glass flakes, glass hollow spheres, carbon fibers, carbon nanotubes, carbon black, talc, mica, wollastonite, calcium carbonate, barium sulfate, magnesium hydroxide, magnesium oxide, tobermorite, halloysite nanotubes, titanium dioxide, zinc sulfide, zinc oxide, iron oxide, and iron sulfide. The amount of the inorganic filler in the resin molded article is preferably 0.002 to 50 parts by mass per 100 parts by mass of the thermoplastic resin (a) in order to improve handling properties when the resin molded article is molded from the resin composition.

Examples of the lubricating oil include natural oils (engine oil, cylinder oil, etc.), synthetic hydrocarbons (paraffin-based oils, naphthene-based oils, aromatic-based oils, etc.), silicone-based oils, and the like. The molecular weight of the lubricating oil may be, for example, 100 or more, or 400 or more, or 500 or more, or may be, for example, 500 ten thousand or less, or 200 ten thousand or less, or 100 ten thousand or less.

The lubricating oil may have a freezing point of, for example, -50 ℃ or higher, or-30 ℃ or higher, or-20 ℃ or higher, and may have a freezing point of, for example, 50 ℃ or lower, or 30 ℃ or lower, or 20 ℃ or lower. The pour point is a temperature 2.5 ℃ lower than the pour point of the lubricating oil, and the pour point can be measured according to JIS K2269.

The content of the lubricating oil relative to 100 parts by mass of the thermoplastic resin (a) is preferably 0.1 part by mass or more, or 0.2 part by mass or more, or 0.3 part by mass or more in terms of improving wear resistance, and is preferably 5.0 parts by mass or less, or 4.5 parts by mass or less, or 4.2 parts by mass or less in terms of avoiding undesirable softening of the resin molded product.

The total amount of the additional component in the main supply material may be, for example, 0.5 mass% or more, or 2 mass% or more, or 20 mass% or less, or 15 mass% or less, or 20 mass% or less.

In a preferred embodiment, the main supply material contains 70 to 99 mass% of the thermoplastic resin (a), 1 to 30 mass% of the cellulose nanofibers (B), and 0 to 20 mass% of an additional component. In another preferred embodiment, the main supply material contains 80 to 95 mass% of the thermoplastic resin (a), 5 to 20 mass% of the cellulose nanofibers (B), and 1 to 15 mass% of the additional component, or contains 85 to 95 mass% of the thermoplastic resin (a), 5 to 15 mass% of the cellulose nanofibers (B), and 2 to 10 mass% of the additional component.

In one embodiment, the melt-mixing is performed in such a manner that the mixing ratio of the auxiliary feed material is greater than 0 mass% and 50 mass% or less, preferably 5 to 50 mass%, with respect to 100 mass% of the total of the main feed material (a1) and the auxiliary feed material (a 2). The mixing ratio of the auxiliary supply material is preferably 5 mass% or more, or 10 mass% or more, or 15 mass% or more, or 20 mass% or more, from the viewpoint of obtaining a favorable anisotropy reducing effect due to the contribution of the cellulose nanofibers (B) from the auxiliary supply material, and is preferably 50 mass% or less, or 45 mass% or less, or 40 mass% or less, or 25 mass% or less, from the viewpoint of obtaining a favorable mechanical strength improving effect due to the contribution of the cellulose nanofibers (B) from the main supply material.

In another embodiment, the mass ratio of the main supply material (a1) to the mass ratio of the auxiliary supply material (a2) in the resin composition (b) may satisfy the following equation.

[ Mass ratio of auxiliary feed Material (a2) ≧ Mass ratio of Main feed Material (a1) ]

That is, 50 mass% or more of the auxiliary supply material may be present in the resin composition. The mass ratio of the auxiliary supply material in the resin composition may be 55 mass% or more, or 60 mass% or more, or 70 mass% or more. The mass ratio of the auxiliary feed material may be less than 100 mass%, and is preferably 90 mass% or less, or 80 mass% or less.

The following describes the steps of the method of the present disclosure by taking embodiment 1 and embodiment 2 as examples, but the method of the present disclosure is not limited to these embodiments.

[ embodiment 1]

Fig. 1 to 3 are diagrams illustrating processes 100,200, and 300 as examples of the method for producing a resin molded body according to embodiment 1. Referring to fig. 1 to 3, in processes 100,200, and 300, a main supply material 11 or its constituent components (i.e., (a) a thermoplastic resin 11a, (B) cellulose nanofibers 11B, and optionally an additional component 11c) are melt-mixed with an auxiliary supply material 12 in a melt-mixing section 101 to produce a resin composition 13 as a melt mixture, and the resin composition 13 is molded in a molding section 102 to produce a resin molded article 14. The resin molded body 14 may have a pellet shape or the like.

< step of preparing Main feed Material and auxiliary feed Material >

The main supply material 11 may be in the form of a mixture containing (a) the thermoplastic resin 11a, (B) the cellulose nanofibers 11B, and optionally the additional component 11c (main supply material 11 in fig. 1 and 2), or may be in the form of (a) the thermoplastic resin 11a, (B) the cellulose nanofibers 11B, and optionally the additional component 11c, which are prepared as constituent components of the main supply material 11, respectively (main supply material 11 in fig. 3). In the latter case, the constituent components of the main feed material are mixed with each other and with the auxiliary feed material in a melt mixing system.

The auxiliary feed material 12 is a melt-processed product of the main feed material 11. The auxiliary supply material 12 may be a material obtained by melting the main supply material 11 alone or a material obtained by recovering a part of the resin molded body 14. In the latter case, as shown in fig. 1 to 3, the main supply material 11 and the auxiliary supply material 12 are melt-mixed and then molded, a part of the obtained resin molded body 14 is separated at a separation point S5 and returned to the melt-mixing section 101 as the auxiliary supply material 12, and the remaining part is recovered as the target resin molded body 14. The auxiliary feed material 12 returned to the melt-mixing portion 101 is melt-mixed with the main feed material 11 newly supplied. By such circulation, the auxiliary feed material 12 is a mixture of plural compositions having different melting times (i.e., thermal history) although it is based on the main feed material 11.

< Process for Forming resin composition >

In this step, the main supply material 11 and the auxiliary supply material 12 are supplied to the melt-mixing section 101 and melt-mixed. In one embodiment, the melt mixing is melt kneading. The melt-mixing section 101 may be a mixing section of a mixing device such as a single-screw extruder, a twin-screw extruder, a roll, or a banbury mixer. Among the above-mentioned mixing devices, a twin-screw extruder is preferable, and more specifically, a twin-screw extruder equipped with a pressure reducing device and a side feeding device can be mentioned. The twin-screw extruder may have an L/D of, for example, 30 to 100, or 35 to 75, or 45 to 70.

The following can be exemplified as the supply steps of the main supply material 11 and the auxiliary supply material 12.

(1) Referring to fig. 1 and 2, a main supply material 11, which is a mixture of (a) a thermoplastic resin, (B) cellulose nanofibers, and optional additional components, is fed into a main supply material feed portion S1 of a melt-mixing section 101, an auxiliary supply material 12 is fed into an auxiliary supply material feed portion S2 of the melt-mixing section 101, and the two are melt-mixed to produce a resin composition 13. The positional relationship between the main feeding material charging portion S1 and the auxiliary feeding material charging portion S2 can be appropriately designed according to the purpose. For example, the auxiliary feeding material input portion S2 (fig. 1) may be disposed downstream of the main feeding material input portion S1, the main feeding material input portion S1 (fig. 2) may be disposed downstream of the auxiliary feeding material input portion S2, or the main feeding material 11 and the auxiliary feeding material 12 may be supplied simultaneously (for example, the main feeding material 11 and the auxiliary feeding material 12 may be supplied separately or mixed in advance).

(2) Referring to fig. 3, the thermoplastic resin 11a (a), the cellulose nanofibers 11B (B), and the optional additional component 11c, which are constituent components of the main supply material 11, are charged into each of the plurality of main supply material charging locations S1a, S1B, and S1c of the melt-mixing section 101, and the auxiliary supply material 12 is charged into the auxiliary supply material charging location S2 of the melt-mixing section 101, whereby the main supply material 11 and the auxiliary supply material 12 are introduced into the melt-mixing system and melt-mixed to produce the resin composition 13. The supply method of the components of the main supply material 11 may be designed according to the purpose, and the components may be supplied to the melt-mixing section 101 individually, or a part of the components may be supplied to the melt-mixing section 101 in a pre-mixed state. Fig. 3 shows an example in which (a) the thermoplastic resin 11a, (B) the cellulose nanofibers 11B, and the optional additional component 11c are sequentially supplied from the upstream side of the melt-mixing section 101, but the order of supply is not limited thereto, and may be set as appropriate depending on the purpose. In the same manner as in the process (1), the positional relationship between the main-supply-material introduction portion S1 and the auxiliary-supply-material introduction portion S2 may be appropriately designed.

The temperature and time of melt mixing can be appropriately set according to the intended resin molded article. From the viewpoint that the effect of improving physical properties by the auxiliary supply material (particularly, the balance between good mechanical strength and less anisotropy) can be obtained well when a part of the resin molded body 14 is used as the auxiliary supply material 12, preferable conditions are (a) a melting start temperature of the thermoplastic resin to +100 ℃ or a melting start temperature of +10 ℃ to +90 ℃ or a melting start temperature of +20 ℃ to +85 ℃ and the melting start temperature referred to herein is a melting point in the case of a crystalline resin and a temperature at which the resin substantially flows easily in the case of an amorphous resin. The reference temperature is the temperature at which the melt mass flow rate is measured. The time is 0.1 to 3 minutes, or 0.2 to 2.5 minutes, or 0.3 to 2.0 minutes. The pressure during the melt mixing may be suitably set according to the purpose, and in a preferred example, the pressure is from-0.1 MPa to 10MPa, or from-0.15 MPa to 8MPa, or from-0.2 MPa to 5 MPa.

< Molding Process >

In this step, the resin composition 13 is fed from the mixing completion point S3 of the melt-mixing section 101 to the molding section 102, molded into a desired shape (for example, pellets, sheets, films, molded bodies having a three-dimensional structure, etc.) in the molding section 102, and the desired resin molded body 14 is taken out from the delivery point S4. In a preferred embodiment, the melt-mixing is melt-kneading, and the melt-kneading and molding are performed in a single kneader (for example, a kneader exemplified in < resin composition forming step >). In another preferred embodiment, the molding is performed by a molding machine (e.g., an injection molding machine) different from the melt kneading.

In one embodiment, a part of the resin molded body 14 is separated at the separation point S5, returned to the melt-mixing portion 101 as the auxiliary supply material 12, and the remaining part is collected as a product. That is, the method of one embodiment further includes a step of returning a part of the resin molded body 14 to the resin composition forming step as at least a part of the auxiliary supply material. Thus, in one embodiment, the resin molded body contains cellulose nanofibers that have undergone a melting process of the main supply material and 2 or more resin composition forming steps. In this embodiment, the proportion of the cellulose nanofibers subjected to the melting treatment of the main supply material and the resin composition forming step 2 or more times is preferably 20% by mass or less, or 15% by mass or less, or 10% by mass or less, relative to 100% by mass of the total amount of the cellulose nanofibers in the resin molded body. When the cellulose nanofibers contain lignin, the cellulose nanofibers preferably do not undergo an excessive thermal history, since coloring, odor (i.e., odor due to decomposition components) and the like are favorably avoided. When the above ratio is within the above range, coloring, odor, etc. can be advantageously avoided. The above ratio may be, for example, 1 mass% or more, 2 mass% or more, or 5 mass% or more, in order to avoid coloring, odor, or the like and also avoid an increase in production cost of the resin molded article.

The shape of the resin molded article of embodiment 1 includes a pellet shape, a sheet shape, a fiber shape, a plate shape, a rod shape, a cylindrical shape, and the like, and the pellet shape is a preferable example in terms of easiness of post-processing and transportation. The pellet shape may be different depending on the cutting manner in the extrusion processing, and may be, for example, circular, oval, cylindrical, or the like. For example, many of the pellets cut by underwater cutting are round, many of the pellets cut by thermal cutting are round or oval, and many of the pellets cut by strand cutting are cylindrical. In the case of round pellets, the pellet diameter may be, for example, 1mm or more and 3mm or less. In the case of cylindrical pellets, the pellet diameter may be, for example, 1mm or more and 3mm or less, and the pellet length may be, for example, 2mm or more and 10mm or less. The pellet size is preferably not less than the lower limit from the viewpoint of the operation stability during extrusion, and not more than the upper limit from the viewpoint of the biting property into the molding machine during the post-processing.

[2 nd embodiment ]

Fig. 4 is a diagram illustrating a process 400 as an example of the method for producing a resin molded body according to embodiment 2. Referring to fig. 4, in a process 400, a main supply material 41 and an auxiliary supply material 42 are melt-mixed in a melt-mixing section 401 to produce a resin composition 43 as a melt mixture, and the resin composition 43 is molded in a molding section 402 to produce a resin molded body 44. The resin molded body 44 may be in a shape (pellet or the like) for further processing, or may be in various product shapes described later.

< step of preparing Main feed Material and auxiliary feed Material >

The main supply material 41 may include a1 st material 41a and a2 nd material 41 b. In one embodiment, the 1 st material 41a is a molten mixture. In one embodiment, the 1 st material 41a is the resin molded body 14 obtained in embodiment 1. In one embodiment, the 1 st material 41a is a molded body comprising 100 parts by mass of (a) a thermoplastic resin and 1 to 50 parts by mass of (B) a cellulose nanofiber.

The auxiliary feed material 42 is a melt-processed product of the main feed material 41. The auxiliary supply material 42 may be a material obtained by melting the main supply material 41 alone, or may be a material obtained by recovering a part of the resin molded body 44. In the latter case, as shown in fig. 4, the main supply material 41 and the auxiliary supply material 42 are melt-mixed and then molded, and a part of the obtained resin molded body 44 is returned to the melt-mixing section 401 as the auxiliary supply material 42, and the remaining part is recovered as the target resin molded body 44. The auxiliary supply material 42 returned to the melt-mixing section 401 is melt-mixed with the main supply material 41 newly supplied. With such circulation, the auxiliary feed material 42 is a mixture of a plurality of compositions having different melting times (i.e., thermal history), although it is based on the main feed material 41.

< Process for Forming resin composition >

In this step, the main supply material 41 and the auxiliary supply material 42 are supplied to the melt-mixing section 401 and melt-mixed. In one embodiment, the melt mixing is melt kneading. The melt-mixing section 401 may be the same as the melt-mixing section 101 of embodiment 1. That is, the melt-mixing section 401 may be a mixing section in a mixing device such as a single screw extruder, a twin screw extruder, a roll, or a banbury mixer. Among the above-mentioned mixing devices, a twin-screw extruder is preferable, and more specifically, a twin-screw extruder equipped with a pressure reducing device and a side feeding device can be mentioned. The twin-screw extruder may have an L/D of, for example, 30 to 100, or 35 to 75, or 45 to 70.

The following can be exemplified as the supply steps of the main supply material 41 and the auxiliary supply material 42.

Referring to fig. 4, the 1 st material 41a and the 2 nd material 41b as the main supply materials 41 are charged into the respective parts of the plurality of main supply material charging parts S1a, S1b of the melt-mixing section 401, the auxiliary supply material 42 is charged into the auxiliary supply material charging part S2 of the melt-mixing section 401, and the two are melt-mixed to produce the resin composition 43. The 1 st material 41a and the 2 nd material 41b may be supplied in a manner designed according to the purpose, and these materials may be supplied to the melt-mixing portion 401 individually or in a premixed state. In fig. 4, an example is shown in which the 1 st material 41a, the 2 nd material 41b, and the auxiliary supply material 42 are sequentially supplied from the upstream side of the melt-mixing section 401, but the order of supply is not limited to this, and may be set as appropriate depending on the purpose. The positional relationship between the main feeding material input point S1 and the auxiliary feeding material input point S2 may be appropriately designed.

The temperature and time of melt mixing can be appropriately set according to the intended resin molded article. From the viewpoint that the effect of improving physical properties by the auxiliary supply material (particularly, the balance between good mechanical strength and less anisotropy) can be obtained well when a part of the resin molded body 44 is used as the auxiliary supply material 42, preferable conditions are (a) a melting start temperature of the thermoplastic resin to +100 ℃ or a melting start temperature of +10 ℃ to +90 ℃ or a melting start temperature of +20 ℃ to +85 ℃ and the melting start temperature referred to herein is a melting point thereof in the case of a crystalline resin and a temperature at which the thermoplastic resin substantially flows easily in the case of an amorphous resin. The reference temperature is the temperature at which the melt mass flow rate is measured. The time is 0.1 to 3 minutes, or 0.2 to 2.5 minutes, or 0.3 to 2.0 minutes. The pressure during the melt mixing may be appropriately set according to the purpose, and in a preferred example, the pressure is 0.01 to 10MPa, or 0.02 to 8MPa, or 0.03 to 5 MPa.

In one embodiment, regarding the relationship between the elastic modulus of the main supply material (a1) and the elastic modulus of the resin composition (b), [ elastic modulus of the resin composition (b) ] or ≧ elastic modulus of the main supply material (a1) × 0.99], or [ elastic modulus of the resin composition (b) ] or ≧ elastic modulus of the main supply material (a1) × 1.00], or [ elastic modulus of the resin composition (b) ] or ≧ elastic modulus of the main supply material (a1) × 1.05], or [ elastic modulus of the resin composition (b) ] or ≧ elastic modulus of the main supply material (a1) × 1.10] is preferable. Such a resin composition (b) is advantageous for providing a resin molded article having excellent elastic modulus. From the viewpoint of ease of production of the resin composition (b), it may be [ elastic modulus of the resin composition (b) ] ≦ elastic modulus of the main supply material (a1 × 1.50], or [ elastic modulus of the resin composition (b) ] ≦ elastic modulus of the main supply material (a1 × 1.40], or [ elastic modulus of the resin composition (b) ] ≦ elastic modulus of the main supply material (a1 × 1.30 ]. The elastic modulus here may be a value obtained by the same measurement method, and may be a flexural modulus or a tensile modulus.

< Molding Process >

In this step, the resin composition 43 is fed from the mixing completion point S3 of the melt-mixing section 401 to the molding section 402, molded into a target shape in the molding section 402, and the target resin molded body 44 is taken out from the feeding-out point S4. The molding portion 402 is configured to perform molding selected from extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decoration molding, heterogeneous material molding, gas-assisted injection molding, foam injection molding, low-pressure molding, ultra-thin wall injection molding (ultra-high-speed injection molding), in-mold composite molding (insert molding, insert-on molding), and the like, for example. In a preferred embodiment, the melt-mixing is melt-kneading, and the melt-kneading and molding are performed in a single kneader (for example, a kneader exemplified in < resin composition forming step >).

In one embodiment, a part of the resin molded body 44 is returned from the auxiliary feeding material input portion S2 to the melt-mixing portion 401, and the remaining part is recovered as a product. That is, the method of one embodiment further includes a step of returning a part of the resin molded body 44 to the resin composition forming step as at least a part of the auxiliary supply material. In this embodiment, for the same reason as described in embodiment 1, the proportion of the cellulose nanofibers subjected to the resin composition forming step 2 or more times may be preferably 20% by mass or less, or 15% by mass or less, or 10% by mass or less, for example, 1% by mass or more, or 2% by mass or more, or 5% by mass or more, with respect to 100% by mass of the total amount of the cellulose nanofibers in the resin molded product.

As the shape of the resin molded body of embodiment 2, various shapes of various molded products can be exemplified in addition to the shape exemplified in embodiment 1. Examples of the product include mechanism components typified by a cam, a slider, a lever, an arm, a clutch, a felt clutch, an idler pulley, a roller, a key lever, a key top, a roller blind, a scroll, a rotary shaft, a joint, a shaft, a bearing, a guide rail, and the like; a resin part molded by insert molding, a chassis, a tray, a side plate, a printer, and a copier; a component for a camera or video device typified by a VTR (video tape recorder), a video camera, a digital video camera, a still camera, and a digital camera; a tape player, DAT, LD (laser Disc), MD (mini Disc), CD (high density Disc) [ including CD-ROM (read only memory), CD-R (recordable type), CD-RW (erasable type) ], DVD (digital video Disc) [ including DVD-ROM, DVD-R, DVD + R, DVD-RW, DVD + RW, DVD-R DL, DVD + R DL, DVD-RAM (random access memory), DVD-Audio ], Blu-ray Disc (Blu-ray (registered trademark) Disc), HD-DVD, other optical Disc drives; music, video, or information devices represented by MFDs (multi-function displays), MO (magneto-optical disks), navigation systems, and notebook computers; a component for communication equipment represented by a mobile phone and a facsimile; a component for electrical equipment; electronic device parts, and the like. In addition, examples of the molded article of the present embodiment include: fuel-related parts such as fuel tanks, fuel pump assemblies, valves, and tank flanges as parts for automobiles; door-related parts represented by door locks, car door handles, window regulators, speaker grilles, and the like; seat belt peripheral components typified by seat belt slip rings, push buttons, and the like; a combination switch unit, switches, clips, and the like; a nib of the mechanical pencil and a mechanism part for pushing out and loading a refill of the mechanical pencil; a washstand, a drain port and a drain cock opening and closing mechanism part; a locking mechanism of the switching part and a commodity discharging mechanism part of the vending machine; rope fasteners, adjusting rings and buttons for clothing; the nozzle and the sprinkling hose for sprinkling are connected with the joint; stair handrails, and building products as floor supports; disposable camera, toy, slide fastener, chain, belt conveyor, belt buckle, sporting goods, vending machine, furniture, musical instrument, industrial machine parts (e.g., electromagnetic equipment case, roller material, transmission arm, medical equipment part, etc.), general machine parts, parts of automobile-railway-vehicle (e.g., outer plate, chassis, aerodynamic part, seat, friction material inside transmission device, etc.), marine parts (e.g., hull, seat, etc.), aviation-related parts (e.g., body, main wing, tail wing, movable wing, cowling, hatch door, seat, interior material, etc.), spacecraft, artificial satellite parts (engine case, main wing, body, antenna, etc.), electronic-electric parts (e.g., personal computer case, mobile phone case, OA equipment, AV equipment, telephone, facsimile machine, etc.) Home electric appliances, toy products, and the like), construction-civil engineering materials (for example, reinforcing bar substitutes, truss structures, suspension bridge cables, and the like), living goods, sports-leisure goods (for example, golf clubs, fishing rods, tennis or badminton rackets, and the like), housing parts for wind power generation, and the like, and container-packaging parts, high-pressure containers filled with hydrogen gas and the like used in fuel cells, and the like.

Properties of resin molded body

In the resin molded article produced by the method of the present disclosure, the fiber length of the cellulose nanofibers (B) is controlled by a unique method, and good mechanical strength and less anisotropy can be achieved at the same time.

In one embodiment, the TD/MD ratio of the molding shrinkage of the resin molded article may be 1.01 to 3.0, or 1.01 to 1.75, or 1.01 to 1.6, or 1.01 to 1.4. The molding shrinkage is a value measured by a method according to ISO 294-4. The molding conditions at this time were determined according to ISO standards describing the molding methods of the resins used. The MD direction and the TD direction correspond to the MD direction and the TD direction, respectively, when the resin molded article is molded. When the TD/MD ratio of the molding shrinkage ratio is within the above range, the anisotropy of the resin molded article is small, and it is preferable.

The tensile strength of the resin molded body may be 90MPa or more, or 95MPa or more, or 100MPa or more, or 110MPa or more in one embodiment. When the tensile strength satisfies the above-mentioned conditions, the mechanical strength of the resin molded article is high, and therefore, the tensile strength is suitable. The tensile strength is a value determined by the method according to ISO 527. The molding conditions suitable for this case are also the same as those described in the description of the molding shrinkage ratio. The tensile strength may be, for example, 300MPa or less, 280MPa or less, or 250MPa or less, from the viewpoint of balance with other characteristics (for example, toughness) of the resin molded product.

In a particularly preferred embodiment, both the TD/MD ratio and the tensile strength of the resin molded article are within the above ranges.

In one embodiment, the molding shrinkage ratio of the resin molded article in the MD direction is preferably 0.1% or more, or 0.2% or more, or 0.3% or more, or preferably 1.2% or less, or 1.0% or less, or 0.7% or less. The molding shrinkage ratio of the resin molded article in the TD direction is preferably 0.4% or more, or 0.5% or more, and preferably 1.2% or less, or 1.0% or less, or 0.9% or less.

In the resin molded article according to one embodiment, the sum of the molding shrinkage ratio in the MD direction and the molding shrinkage ratio in the TD direction may be 0.5% to 2.6%, or 0.5% to 1.9%, or 0.6% to 1.6%, or 0.8% to 1.5%.

In the resin molded article of one embodiment, when the TD/MD ratio of the molding shrinkage ratio of the resin molded article is Rb and the TD/MD ratio of the molding shrinkage ratio of the comparative resin molded article using only the main supply material is Ra1, [ Rb ] < [ Ra1], or [ Rb ] < [ Ra 1X 0.95], or [ Rb ] < [ Ra 1X 0.90], or [ Rb ] < [ Ra 1X 0.85] is preferable. Such a resin molded article is advantageous in that anisotropy of molding shrinkage is small. The relationship between Ra1 and Rb may be, for example, [ Rb ] > [ Ra1 × 0.50], or [ Rb ] > [ Ra1 × 0.60], or [ Rb ] > [ Ra1 × 0.70] in view of ease of production of a resin molded article.

The linear expansion coefficient (MD direction) of the resin molded body in the temperature range of 0 ℃ to 60 ℃ is preferably 60ppm/K or less, or 50ppm/K or less, or 45ppm/K or less, or 35ppm/K or less. The lower limit of the linear expansion coefficient is not particularly limited, but is preferably 5ppm/K or more, or 10ppm/K or more, for example, from the viewpoint of ease of production. The linear expansion coefficient is a value determined in accordance with ISO 11359-2.

In one embodiment, the difference between the Yellowness (YI) value of the resin molded article and the Yellowness (YI) value of the auxiliary supply material may be 10 or less, or 8 or less, or 7 or less. The Yellowness (YI) value is a value measured by a method according to JIS K7373.

Examples

The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. The main measured values of the physical properties were measured by the following methods.

< tensile Strength >

The obtained pellet-shaped molded article was molded into a multipurpose test piece in accordance with ISO294-1 using an injection molding machine. The tensile yield strength of the obtained multipurpose test piece was measured in accordance with ISO 527-1. For the molded pieces that broke before yielding, their maximum strength was substituted.

< mold shrinkage/mold shrinkage ratio >

The obtained pellet-shaped molded article was molded into a flat plate of 60mm × 60mm × 2mm and 60mm × 80mm × 2mm as specified in JIS K7152-3 using an injection molding machine. For examples 1 to 21 and comparative examples 1 to 5, plates 60mm × 60mm × 2mm were used, and for examples 22 and comparative examples 6 and 7, plates 60mm × 80mm × 2mm were used. For the flat plate-like molded piece, the dimensions in the resin flow direction (MD) and the direction perpendicular to the flow direction (TD) were precisely measured in accordance with ISO294-4, and the shrinkage was calculated. The obtained shrinkage ratio in the TD direction was divided by the shrinkage ratio in the MD direction to calculate the molding shrinkage ratio.

< yellowness index Change Δ YI >

The yellow index was measured according to JIS K7373 using a flat plate molded for molding shrinkage measurement. At this time, the difference between the Yellowness (YI) value of the obtained resin molded article and the Yellowness (YI) value of the auxiliary supply material was calculated and used as the yellowness change rate (. DELTA.YI).

< warpage of Flat plate >

The obtained pellet-like molded article was molded into a flat plate having a width of 50mm, a length of 70mm and a thickness of 1mm and having a pinhole gate with a diameter of 1mm by using an injection molding machine. The mold temperature was adjusted to 25 ℃ at this time. The warped convex portion of the obtained flat plate-shaped molding piece was faced downward on the smooth surface, one side of the gate side was pressed against the surface, and the gap between the molding piece on the opposite side and the smooth surface was measured. In the measurement, the gap is photographed and measured. The measurement was performed on at least 5 flat plates, and the average of 3 values excluding the maximum and minimum was taken as the warpage value.

< number of Large clumps >

The obtained pellet-like molded article was cut with a microtome in a direction perpendicular to the flow direction to obtain a smooth surface, and a photograph was taken with an optical microscope (BX 53M: manufactured by Olympus). The 3 points of the pellet-shaped molded article were photographed. The obtained photograph was binarized by an image analyzer, and the total number of equivalent circle diameters of 5 μm or more was calculated.

< materials used >

(A) Thermoplastic resin

Polyamide 6 (hereinafter referred to as PA6)

UBE Nylon 1013 manufactured by Utsu Kyoho Kagaku K.K.

Viscosity number: 120

Ratio of carboxyl end groups ([ COOH ]/[ all end groups ]): 0.6

Polypropylene (hereinafter referred to as PP)

NOVATEC PP MA1B (Japan Polypropylene Co., Ltd.)

MFR (230 ℃, load 21.2N) ═ 21g/10 min

(B) Cellulose nanofiber (CNF for short)

CNFs not substituted by acetylation and 3 CNFs different in degree of substitution were prepared by the following preparation examples.

[ preparation example 1]

(fiber opening step)

The cotton linter pulp was cut and stirred in a single screw stirrer (DKV-1. phi. 125mm dissolver manufactured by IMEX Co.) at 500rpm for 1 hour at normal temperature. Subsequently, the resulting mixture was charged into a bead mill (NVM-1.5, manufactured by IMEX corporation) by a hose pump and circulated for 120 minutes to obtain an opened CNF slurry.

In the circulation operation, the rotational speed of the bead mill was 2500rpm, and the peripheral speed was 12 m/s. As the beads, zirconium oxide beads having a particle diameter of 2.0mm were used so that the packing ratio was 70% (in this case, the gap between the beads in the bead mill was 0.6 mm). In the circulation operation, in order to absorb heat generated by friction, temperature control was performed so that the slurry temperature was 40 ℃.

The properties of the obtained open CNF were evaluated, and as a result, the diameter was 65nm and the L/D was about 450.

(acetylation step)

To 100 parts by mass of the opened CNF slurry obtained in the opening step, 11 parts by mass of vinyl acetate and 1.63 parts by mass of sodium bicarbonate were charged into a bead mill apparatus, and then a circulation operation was performed to obtain an acetylated CNF slurry. The conditions of the circulation operation are the same as those in the opening step. The operation was carried out under three conditions of 30 minutes, 60 minutes and 120 minutes of cycle time, and acetylated CNF slurries having different degrees of substitution were obtained.

The degrees of substitution of CNFs obtained under the respective conditions were measured, and as a result, the degree of substitution of CNF was 0.50 for 30 minutes, 1.02 for 60 minutes, and 1.49 for 120 minutes.

(Water replacement step)

192 parts by mass of pure water was added to 100 parts by mass of the obtained opened CNF slurry or acetylated CNF slurry, and the mixture was thoroughly stirred and then placed in a dehydrator for dehydration and concentration to obtain a wet cake. The obtained wet cake was dispersed again in the same amount of pure water, stirred and concentrated, and the washing operation was repeated 5 times in total to perform solvent substitution.

(drying Process)

The concentration of the opened CNF wet cake and each acetylated CNF wet cake was adjusted to 10 mass% with pure water, 5 mass parts of PEG20000 was added to 100 mass parts of CNF, and after sufficient stirring, vacuum drying was performed at about 40 ℃ using a revolution-rotation type stirrer (V-mini 300 manufactured by EME corporation), thereby obtaining each CNF dry powder.

< apparatus >

< melt mixing device >

A co-rotating twin screw extruder (TEM26 SX: manufactured by TOSHIBA MACHINE) having 15 temperature adjusting barrels with an L/D of 4 of 60 was used, a throat for feeding a raw material (hereinafter, simply referred to as a throat) was provided in a barrel 1 which is the most upstream barrel of the extruder, side feeders for feeding a raw material (hereinafter, a side feeder provided in the barrel 4, simply referred to as a side feeder 1, and a side feeder provided in the barrel 7, simply referred to as a side feeder 2) were provided in the barrel 4 and the barrel 7, and a pressure reducing port for devolatilization was provided in the barrel 14.

Regarding the screw design, the design was as follows: a "clockwise screw (hereinafter abbreviated as" RS ") is disposed at a position where L/D is 0 to 18 (center of barrel 1 to barrel 5), 2" clockwise kneading discs (hereinafter abbreviated as "RKD"), 3 "neutral kneading discs (hereinafter abbreviated as" NKD "), and 1" counterclockwise kneading discs (hereinafter abbreviated as "LKD") are sequentially disposed at a position where L/D is 19 to 24 (center of barrel 5 to barrel 6), RS is disposed at a position where L/D is 24 to 32 (barrel 7 to barrel 8), 1 RKD, 2 NKD, 1 RKD, and 2 NKD are sequentially disposed at a position where L/D is 32 to 36 (barrel 9), RS is disposed at a position where L/D is 36 to 40 (barrel 10), and 1 RKD, 2 NKD, 1D, 3 NKD, and 48 to 44 (barrel 11) are sequentially disposed at a position where L/D is 48 to 44 (barrel 11), 2 NKDs, 1 LKD, 3 NKDs, and 1 "counterclockwise screw (hereinafter abbreviated as LS)" are sequentially arranged at positions where L/D is 48 to 52 (cylinder 13), RS is arranged at positions where L/D is 52 to 56 (cylinder 14), 1 RS and 3 NKDs are sequentially arranged at positions where L/D is 56 to 60 (cylinder 13), and then all the others are RS.

A die having 2 spinnerets each having a diameter of 3mm was provided at the tip of the extruder, and the molten resin was extruded into a strand-like form.

< Molding apparatus >

The molten strand was cooled in a water tank provided in a subsequent step of the melt mixing apparatus, and cut into pellets in a subsequent pelletizer, thereby obtaining pellet-shaped resin molded articles. A part of the obtained pellet-shaped resin molded article was used as an auxiliary supply material. (the shape of the auxiliary feed material is hereinafter referred to as "pellet")

The pellet-like resin molded article thus obtained was molded at an injection speed of 300 mm/sec using an injection molding machine (manufactured by Sodick Plustech: TR05EH2, clamping pressure of 5 tons) and FPC connector (length: 30mm, width: 1mm, 2, 50 pin holes, pin hole pitch: 0.5milli pitch) mold. The connector-shaped molded body was pulverized by a pulverizer, and the diameter was adjusted to 5mm or less by using a mesh to obtain a pulverization assisting material. (hereinafter, the shape of the auxiliary feed material is referred to as "crushed product")

[ preparation example 2]

The barrel temperature of the melt mixing device was set to 150 ℃ in barrel 1 to 3, 250 ℃ in barrel 4 to 15 and a die head, and 60 mass% of PA6 and 40 mass% of CNF having a substitution degree of 1.02 were supplied from a throat part and melt-mixed to obtain a high-concentration PA/CNF pellet (hereinafter abbreviated as PA/CNFMB). The screw speed of the melt mixing device at this time was 300rpm, and the discharge amount per unit time was 18 kg/hr.

[ preparation example 3]

All the operations were carried out in the same manner as in production example 2 except that the barrel temperature of the melt mixing apparatus was set to 100 ℃ in barrels 1 to 3, the barrel temperature of barrels 4 to 15 and the die temperature were set to 200 ℃ and the PA6 was changed to PP, thereby obtaining a granular PP/CNF high-concentration product (hereinafter abbreviated as PP/CNF-MB).

Examples 1 to 16 and comparative examples 1 to 5

Regarding the setting of the barrel temperature of the melt mixing device, barrel 1 to 3 were set to 150 ℃, barrel 4 to 7 were set to 260 ℃, barrel 8 to 15 and the die head were set to 250 ℃, the main feed material was fed from the position of addition of the main feed material so as to have the composition described in tables 1 and 2, the auxiliary feed material as a melt mixture of the main feed material was fed from the position of addition of the auxiliary feed material, melt mixing was performed to obtain pellet-shaped resin molded bodies, and various properties were evaluated and are described in tables 1 and 2. The screw speed of the melt mixing device at this time was 300rpm, and the discharge amount per unit time was 25 kg/hr.

The "processes" described in the table refer to the processes 100,200,300, and 400 used in the description of the present embodiment.

The pellets of comparative example 1 were used as the auxiliary feed materials (auxiliary feed materials 12 in the process flow) of examples 1 to 11. In addition, the auxiliary feed material (auxiliary feed material 12 of the process flow) of example 12 used the pellets of comparative example 3 as the auxiliary feed material, and example 13 used the pellets of comparative example 5 as the auxiliary feed material.

The pulverized product of the auxiliary supply material used in example 6 was obtained by molding the pellet-shaped resin molded article obtained above into a connector-shaped resin molded article and then pulverizing the molded article.

The main feed material of example 9 was supplied from the throat portion to PA6, and from the side feed portion 1 to CNF. The separate supply of the CNF powder can suppress the fluctuation in the supply of the CNF powder, and the unexpected effect of obtaining a small variation in the tensile strength between test pieces due to the stable supply is likely to be obtained.

Comparative examples 1,3 and 5 are examples in which no auxiliary feed material was added. Comparative examples 2,4, 6 and 7 are of a type in which the main feed material is not used, that is, of a type in which only the auxiliary feed material is used, and correspond to 100% recycling (recycling).

[ examples 17 to 21]

Various properties were evaluated in the same manner as in example 10 except that the setting of the barrel temperature of the melt mixing device was changed to 100 ℃ for barrels 1 to 3, 200 ℃ for barrels 4 to 7, and 190 ℃ for barrels 8 to 15 and the die head, and the compositions and conditions described in table 3 were changed. The results are set forth in table 3.

[ Table 3]

Example 22 and comparative examples 6 and 7

Various characteristics were evaluated in the same manner as in example 1, except that the discharge amount per unit time of the melt mixing device was changed to 10kg/hr and the compositions and conditions in Table 4 were changed. The results are set forth in Table 4. In comparative examples 6 and 7, only the auxiliary feed material was used, and the method corresponded to 100% recycling (recycling). In comparative example 7, the treatment was performed 2 times by the process 100.

[ Table 4]

In comparative examples 6 and 7, the tensile strength was significantly reduced, and the performance was poor.

Industrial applicability

The method for producing a resin molded article of the present invention can be suitably applied to the production of a resin molded article used in applications requiring physical properties such as good mechanical strength and little anisotropy.

Description of the symbols

100,200,300,400 process

101,401 melt mixing section

102,402 Molding section

11,41 Main feed Material

11a (A) thermoplastic resin

11b (B) cellulose nanofibers

11c optional additional component

12,42 auxiliary feed material

13,43 resin composition

14,44 resin molded article

41a 1 st Material

41b 2 nd Material

Main feeding material input part of S1, S1a, S1b and S1c

S2 auxiliary feeding material input part

S3 mixing end part

S4 delivery site

S5 separation site