阅读说明：本技术 低孔隙的粒料以及成型体的制造方法 (Low-porosity pellet and method for producing molded body ) 是由 谷本一洋 于 2020-05-13 设计创作，主要内容包括：本发明提供一种粒料、以及使用了该粒料的成型体的制造方法,该粒料是包含热塑性树脂和纤维素纳米纤维的粒料,能够制造具有良好的外观且黄变得到了抑制的成型体。在一个方式中,提供一种包含热塑性树脂和纤维素纳米纤维的粒料,其中,每100个粒料中的含孔隙粒料的个数为10个以下。另外,在一个方式中,提供一种成型体的制造方法,其包括准备上述粒料的工序、以及将该粒料在模具内注射成型而得到成型体的工序。(The invention provides a pellet and a method for manufacturing a molded body using the pellet, wherein the pellet is the pellet comprising a thermoplastic resin and cellulose nano-fiber, and the molded body which has good appearance and is prevented from yellowing can be manufactured. In one embodiment, there is provided a pellet comprising a thermoplastic resin and a cellulose nanofiber, wherein the number of the void-containing pellets per 100 pellets is 10 or less. In one embodiment, there is provided a method for producing a molded article, comprising the steps of preparing the pellet and injection molding the pellet in a mold to obtain a molded article.)

1. A pellet of a resin composition comprising a thermoplastic resin and a cellulose nanofiber, wherein the number of the void-containing pellets per 100 pellets is 10 or less.

2. The pellet of claim 1 wherein the ratio of void area to cross-sectional area in the TD cross-section of the pellet is 4.0% or less.

3. The pellet as claimed in claim 1 or 2, wherein the number of the void-containing pellets per 100 pellets is 1 or less.

4. A pellet as claimed in any one of claims 1 to 3 wherein the angle formed by the normal direction of the cross section of the pellet relative to the MD direction of the pellet is in the range of from 5 ° to 30 °.

5. A pellet as claimed in any one of claims 1 to 4 wherein the TD cross-section of the pellet has a minor diameter of from 2mm to 5 mm.

6. The pellet as claimed in any one of claims 1 to 5, which comprises 0.1 to 30 mass% of the cellulose nanofibers.

7. The pellet of any one of claims 1 to 6, wherein the cellulose nanofibers have a fiber diameter of 50nm to 1000nm and a fiber length/fiber diameter (L/D) ratio of 30 or more.

8. The pellet of any one of claims 1 to 7, wherein the cellulose nanofibers are hydrophobized cellulose nanofibers.

9. The pellet as claimed in any one of claims 1 to 8, wherein the thermoplastic resin is a polyamide-based resin and/or a polyolefin-based resin.

10. The pellet of any one of claims 1-9, further comprising an elastomer.

11. The pellet of any one of claims 1 to 10, further comprising: cellulose nanocrystals having a crystal diameter of 100nm or less and an L/D of less than 30, cellulose microfibrils having a fiber diameter of more than 1 μm and 50 μm or less, or a mixture thereof.

12. The pellet as claimed in any one of claims 1 to 11, wherein a difference Tcc-Tcp between a temperature-decreasing crystallization peak temperature Tcc of the resin composition measured by a differential scanning calorimeter and a temperature-decreasing crystallization peak temperature Tcp of the thermoplastic resin measured by a differential scanning calorimeter is 5 ℃ to 30 ℃.

13. A pellet as claimed in any one of claims 1 to 12 wherein the pellet has a ratio of total void volume (Ve) to total volume of cellulose nanofibres (Vc) per 100 pellets of Ve/Vc in the range of 0 to 4 vol%.

14. The resin composition according to any one of claims 1 to 13, wherein,

the resin composition further comprises a resin crystallization temperature lowering agent,

the resin crystallization temperature reducing agent is a compound which reduces the temperature reduction crystallization peak temperature of the resin composition measured by a differential scanning calorimeter by 5 to 30 ℃.

15. A method for producing a molded article, comprising the steps of:

a step of preparing the pellet according to any one of claims 1 to 14; and

and a step of injection molding the pellets in a mold to obtain a molded article.

Technical Field

The present invention relates to a low-porosity pellet and a method for producing a molded article using the pellet.

Background

Conventionally, various fillers have been blended in molded articles mainly composed of thermoplastic resins to improve physical properties, and in view of recent increasing interest in environmental problems, a technique of using cellulose derived from natural products as the filler has been studied. In the production of a molded article comprising a thermoplastic resin and cellulose, the following steps are generally performed: a resin composition containing a thermoplastic resin and cellulose is extruded in a molten state into a strand shape, cooled, cut by a pelletizer to form pellets, and then the pellets are melted again to form a desired molded article.

In addition, recently, among cellulose, Cellulose Nanofibers (CNF) having an extremely fine structure and expected to have an excellent effect of improving physical properties in a molded article have been attracting attention. Regarding the production of pellets comprising a thermoplastic resin and cellulose nanofibers, patent document 1 describes a molding material mixture comprising at least one base material selected from the group consisting of a resin and a fiber and cellulose nanofibers, characterized in that a hydrophobic polymer is chemically bonded to at least a part of-OH groups of the cellulose nanofibers, and the base material and the cellulose nanofibers are pulverized or pelletized.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-16896

Disclosure of Invention

Problems to be solved by the invention

In the technique described in patent document 1, at least a part of — OH groups of cellulose nanofibers are capped with a hydrophobic polymer, whereby hydrogen bonds between cellulose fibers are prevented from being generated and a molding material mixture stable in a state of being pulverized or being pelletized can be obtained. However, according to the studies of the present inventors, it has been found that voids are likely to be generated in the interior (particularly in the central portion) of pellets when a resin composition containing a thermoplastic resin and cellulose nanofibers is molded into pellets, and that silver streaks (poor appearance) are likely to be generated on the surface of a molded article when such pellets having voids are used as a raw material to produce a molded article, and the yellowness of the molded article is improved.

An object of the present invention is to solve the above problems and to provide a pellet which is a pellet containing a thermoplastic resin and a cellulose nanofiber and which can produce a molded article having a good appearance and suppressed yellowing, and a method for producing a molded article using the pellet.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, have found that a molded article in which appearance defects such as silver streaks and yellowing are suppressed can be produced by using pellets in which voids are appropriately controlled, thereby completing the present invention.

That is, the present invention includes the following aspects.

[1] A pellet of a resin composition comprising a thermoplastic resin and a cellulose nanofiber, wherein the number of the void-containing pellets per 100 pellets is 10 or less.

[2] The pellet according to mode 1, wherein the ratio of the pore area to the cross-sectional area in the TD cross-section of the pellet is 4.0% or less.

[3] The pellet according to the above aspect 1 or 2, wherein the number of the void-containing pellets per 100 pellets is 1 or less.

[4] The pellet according to any one of the above aspects 1 to 3, wherein an angle formed by a normal direction of a cross section of the pellet with respect to an MD direction of the pellet is 5 ° to 30 °.

[5] The pellet according to any one of the above aspects 1 to 4, wherein the short diameter of the TD cross section of the pellet is 2mm to 5 mm.

[6] The pellet according to any one of the above aspects 1 to 5, which comprises 0.1 to 30 mass% of the cellulose nanofibers.

[7] The pellet according to any one of the above aspects 1 to 6, wherein the cellulose nanofibers have a fiber diameter of 50 to 1000nm and a fiber length/fiber diameter (L/D) ratio of 30 or more.

[8] The pellet according to any one of the above aspects 1 to 7, wherein the cellulose nanofibers are hydrophobized cellulose nanofibers.

[9] The pellet according to any one of embodiments 1 to 8, wherein the thermoplastic resin is a polyamide resin and/or a polyolefin resin.

[10] The pellet as described in any one of embodiments 1 to 9, further comprising an elastomer.

[11] The pellet as described in any of the above modes 1 to 10, further comprising: cellulose nanocrystals having a crystal diameter of 100nm or less and an L/D of less than 30, cellulose microfibrils having a fiber diameter of more than 1 μm and 50 μm or less, or a mixture thereof.

[12] The pellet as described in any one of embodiments 1 to 11, wherein a difference Tc-Tcp between a temperature-decreasing crystallization peak temperature Tcc of the resin composition measured by a differential scanning calorimeter and a temperature-decreasing crystallization peak temperature Tcp of the thermoplastic resin measured by a differential scanning calorimeter is 5 to 30 ℃.

[13] The pellet according to any one of the above aspects 1 to 12, wherein a ratio Ve/Vc of a total volume (Ve) of pores of the pellet to a total volume (Vc) of the cellulose nanofibers is 0 to 4 vol% per 100 pellets.

[14] The resin composition according to any one of the above aspects 1 to 13, wherein,

the above resin composition further comprises a resin crystallization temperature lowering agent,

the resin crystallization temperature reducing agent is a compound which reduces the temperature reduction crystallization peak temperature of the resin composition measured by a differential scanning calorimeter by 5 to 30 ℃.

[15] A method for producing a molded article, comprising the steps of:

a step of preparing the pellet according to any one of the above aspects 1 to 14; and

and a step of injection molding the pellets in a mold to obtain a molded article.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided a pellet which is a pellet containing a thermoplastic resin and cellulose nanofibers and which can produce a molded article having a good appearance and suppressed in yellowing, and a method for producing a molded article using the pellet.

Drawings

Fig. 1 is a diagram illustrating a cross section of a pellet.

Fig. 2 is a diagram illustrating a mode in which a cross section of the pellet is inclined.

Fig. 3 is a diagram illustrating a mode in which the cross section of the pellet is inclined.

Detailed Description

The present invention will be described below with reference to exemplary embodiments thereof, but the present invention is not limited to these embodiments.

[ pellets ]

One embodiment of the present invention provides a pellet comprising a thermoplastic resin and cellulose nanofibers. In one embodiment, the number of the void-containing pellets per 100 pellets is 10 or less. The "granule containing pores" in the present disclosure means a granule having at least 1 identifiable pore when the granule is cut at the center in the MD direction of the granule (i.e., the MD direction (mechanical direction) when the granule is formed) along the TD direction of the granule (i.e., the TD direction (lateral direction) when the granule is formed) to obtain the TD cross section of the granule and observed with a microscope. Specifically, 100 randomly selected pellets were cut at the center in the MD direction of the pellets, and flattened by a microtome to obtain a TD cross section. The morphological image of the TD cross section was taken with a microscope under a condition of 20-fold magnification and an observation field of 10mm × 14mm, and the pellet having a recognizable pore was determined to be a pore-containing pellet.

As for the reason why voids are generated in the pellet containing the thermoplastic resin and the cellulose nanofibers, it is considered that the cellulose nanofibers function as a nucleating agent for the thermoplastic resin when the strand is cooled after the cellulose nanofibers are mixed with the thermoplastic resin in a molten state to form the strand. In particular, when the cooling rate of the strand is high, crystallization of the thermoplastic resin that causes solidification of the strand proceeds more rapidly in the vicinity of the surface than in the interior of the strand, and therefore, it is considered that voids are likely to be generated in the interior of the strand. In addition, it is believed that thixotropy that cellulose nanofibers may exhibit in the resin composition is also a cause of voids. That is, in the production of pellets, melt mixing (e.g., melt kneading) of a resin composition containing a thermoplastic resin and cellulose nanofibers is generally performed, followed by cooling, and the shearing force applied to the resin composition during melt mixing is generally low. It is considered that, under such a low shear force, the generation of voids is caused by the high viscosity of the resin composition due to the thixotropy of the cellulose nanofibers. When a molded article is produced using such a pellet having voids as a molding material, it is considered that the presence of air during molding causes appearance defects of the molded article and yellowing due to deterioration of the resin composition. The pellet of one embodiment of the present invention has a small number of voids, and therefore can be used for producing a molded article having a good appearance and suppressed yellowing.

Further, if the amount of the void-containing pellets is small, the pellet-biting property in producing a molded article by melting the pellets can be improved, and the molding cycle can be shortened, so that it is advantageous in terms of improving the productivity and suppressing the decomposition of the thermoplastic resin and the cellulose nanofibers.

In one embodiment, the number of the void-containing pellets per 100 pellets comprising the thermoplastic resin and the cellulose nanofibers is 10 or less, preferably 8 or less, more preferably 5 or less, further preferably 3 or less, further preferably 1 or less, and most preferably 0, from the viewpoint of obtaining a molded article with less appearance defects and yellowing. The smaller the number of the void-containing pellets, the more preferable the molded article having less appearance defects and yellowing is obtained, but the number of the void-containing pellets may be, for example, 1 or more, or 3 or more, or 5 or more, from the viewpoint of ease of production of the pellets. That is, in one embodiment, the proportion of the number of the void-containing granules needs to be 10% by number or less, preferably 8% by number or less, more preferably 5% by number or less, further preferably 3% by number or less, further preferably 1% by number or less, and most preferably 0% by number.

In order to obtain a molded article with less appearance defects and yellowing, the ratio of the pore area to the cross-sectional area (hereinafter also referred to as the pore area ratio) in the TD cross-section of the pellet is preferably 4.0% or less, more preferably 2.5% or less, and still more preferably 1.0% or less. The pore area ratio is a value obtained by the following method. First, for 100 pellets randomly selected, void-containing pellets were determined using the method of the present disclosure. For the void-containing pellets, the void area in the TD section was measured by using the software attached to the microscope, the ratio of the void area to the total cross-sectional area of the TD section was calculated as 100%, and the average value in the entire void-containing pellets was taken as the void area ratio. In the randomly selected 100 pellets, the void area ratio in the case where 1 pellet containing voids was not contained was 0%. From the viewpoint of obtaining a molded article with less defects and yellowing, the lower the void area ratio is, the more preferable is 0%; from the viewpoint of ease of production of the pellets, it may be, for example, 0.5% or more, 1.0% or more, or 2.0% or more. In a more preferred embodiment, the number of the void-containing pellets per 100 pellets is 8 or less, or 5 or less, or 3 or less, and the void area ratio is any of the above ranges. In a particularly preferred embodiment, the number of the pore-containing granules per 100 granules is 0 (therefore, the above pore area ratio is 0%).

The shape of the pellet may be selected according to the purpose, and typically, a spherical shape, an ellipsoidal shape, a cylindrical shape, an elliptic cylindrical shape, or the like is exemplified. The shape of the cross section of the TD pellet may be typically circular (in the case where the pellet is a sphere, a cylinder, or the like) or elliptical (in the case where the pellet is an ellipsoid, an elliptic cylinder, or the like), but may also be polygonal (triangle, quadrangle, pentagon, hexagon, or the like), irregular (star, C, O, or the like), or the like.

In one embodiment, the short diameter of the TD cross section of the pellet may be, for example, 1mm or more, or 2mm or more, or 2.2mm or more, or 2.5mm or more, and may be, for example, 5mm or less, or 4mm or less, or 3mm or less, from the viewpoint of facilitating mass production of the pellet and a molded article using the same. In the present disclosure, the minor axis of the cross section of the pellet TD means the maximum value among the diameters (1 or 2 or more diameters may be present depending on the shape of the cross section of the pellet TD) that the inscribed circle may have when the inscribed circle is drawn for the outer shape of the cross section of the pellet TD. For example, in the case where the cross section of the pellet TD is a circle, the minor axis is the diameter of the circle; when the cross section of the pellet TD is an ellipse, the minor axis is the length of the minor axis of the ellipse.

As a more specific example, in the case where the pellet is spherical or ellipsoidal, the minor diameter of the TD section of the pellet is preferably 2mm to 5 mm. When the pellet is cylindrical or elliptic, the short diameter of the TD cross section of the pellet is preferably 2mm to 5mm, and the MD length of the pellet is preferably 2mm to 5 mm. The above-mentioned short diameter and length are preferably not less than the lower limit from the viewpoint of the operation stability at the time of extrusion, and not more than the upper limit from the viewpoint of the biting property into the molding machine in the post-processing.

Fig. 1 is a diagram illustrating a cross section of a pellet, and fig. 2 and 3 are diagrams illustrating a mode in which the cross section of the pellet is inclined. Referring to fig. 1, when the strand is cut into pellets 1 (i.e., pelletized), the normal direction L1 of the cross section S1 is mostly parallel to the strand MD direction L. However, depending on the production conditions such as the condition of high strand temperature in pelletization, the condition of using large equipment (i.e., a large amount of discharged composition), and the condition of high line speed, the normal directions L1 and L2 may be inclined (i.e., not substantially parallel) at an angle of θ 1 and θ 2 (the angle is an angle on the acute angle side, to be noted) with respect to the strand MD direction L, as shown in fig. 2 and 3. The pellet cross section may be one surface such as pellet cross section S1 shown in fig. 2, may be two surfaces such as pellet cross sections S1 and S2 shown in fig. 3, or may be 3 or more surfaces. In a representative embodiment, the cross-section of the pellet is substantially planar.

Referring to fig. 2 and 3, in one embodiment, the angles θ 1 and θ 2 formed by the normal directions S1 and S2 of the pellet sections S1 and S2 with respect to the MD direction L of the pellets may be 5 ° to 30 °, in order to facilitate mass production of pellets and molded articles using the pellets. The pellet shape can be controlled relatively uniformly in small-scale production and is difficult to control uniformly in large-scale production (e.g., 100kg/h scale). The pellets having an angle of 5 ° to 30 ° are easy to mass-produce and are preferable. The angle may be more preferably 8 ° to 20 °, or 10 ° to 15 °. The angle is a value obtained by the following method. First, 10 randomly selected pellets were cut in a visually selected direction so as to pass through the center portion of the pellet TD direction and so as to maximize the pellet cross-section inclination angle described later, and the cut was further flattened by a slicer to obtain an MD cross-section. The morphological image of the MD cross section was taken with a microscope under conditions of 20-fold magnification and 10mm × 14mm observation field. The MD direction axis of the pellet and the normal line to the line segment corresponding to the MD direction end face of the pellet are defined on the morphological image, and the angle formed by the MD direction axis of the pellet and the normal line is measured. The number average of 10 pellets was obtained as the pellet section inclination angle.

The pellet contains a thermoplastic resin and cellulose nanofibers, and in one embodiment, may further contain an optional additional component. The following examples illustrate the ingredients.

Thermoplastic resin

As the thermoplastic resin, various resins can be used, and examples thereof 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 ℃. The thermoplastic resin is composed of 1 or 2 or more kinds of polymers, and the polymers may be homopolymers or copolymers.

The melting point of the crystalline resin as referred to herein is the peak top temperature of the endothermic peak which appears when the temperature is raised from 23 ℃ at a temperature raising rate of 10 ℃/min 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 of the endothermic peak at this time is preferably 10J/g or more, more preferably 20J/g or more. In the measurement, it is preferable to use a sample obtained by heating a sample to a temperature of not less than the melting point +20 ℃ at a time to melt the resin and then cooling the resin to 23 ℃ at a cooling rate of 10 ℃/min.

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 peaks of loss modulus appear, the peak top temperature of the peak on the highest temperature side is referred to. In order to improve the measurement accuracy, the measurement frequency is preferably measured at least 1 time within 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 as small as possible in terms of heat conduction.

Examples of the thermoplastic resin 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, polyether sulfone resins, polyketone resins, polyphenylene ether ketone resins, polyimide resins, polyamide imide resins, polyether imide resins, polyurethane resins, polyolefin resins (for example, α -olefin (co) polymers), polyvinyl resins, 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. In addition, a modified product modified with at least one compound selected from an unsaturated carboxylic acid, an acid anhydride thereof, and a derivative thereof may be used as the thermoplastic resin.

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. In addition, when the thermoplastic resin is a polyamide resin and/or a polyolefin resin, the advantages provided by the pellet of the present embodiment are particularly remarkable and preferable.

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, and the like, polypropylene, poly-1-butene, poly-1-pentene, polymethylpentene, ethylene- α -olefin copolymers or modified products thereof (e.g., ethylene-propylene copolymers, ethylene-butene copolymers, and modified products thereof), copolymers of olefins (e.g., α -olefins) with other monomer units (e.g., ethylene- (meth) acrylic acid copolymers, ethylene- (meth) methyl acrylate copolymers, ethylene- (meth) ethyl acrylate copolymers, ethylene-glycidyl methacrylate copolymers, ethylene-co-polymers, Ethylene-propylene-diene terpolymers, ethylene-vinyl acetate copolymers, copolymers of a non-conjugated olefin and a conjugated diene, copolymers of ethylene and/or propylene and an unsaturated carboxylic acid and/or an unsaturated carboxylic acid ester, polyolefins obtained by metalating at least a part of the carboxyl groups of copolymers of ethylene and/or propylene and an unsaturated carboxylic acid and/or an unsaturated carboxylic acid ester, halogenated isobutylene-p-methylstyrene copolymers, and modified products thereof). The polyolefin resin may be a cycloolefin resin.

The most preferred polyolefin resin herein is polypropylene. Particularly preferred is a polypropylene having a Melt Flow Rate (MFR) of 3g/10 min or more and 100g/10 min or less as measured at 230 ℃ under a load of 2.16kgf in accordance with ISO 1133. 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 75g/10 min, still more preferably 60g/10 min, and most preferably 40g/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, an acid-modified polyolefin resin can be suitably used. The acid can be suitably selected from maleic acid, fumaric acid, succinic acid, phthalic acid and anhydrides thereof, and polycarboxylic acids such as citric acid. Among these, maleic acid or an anhydride thereof is preferable in terms of improving the ease of modification. The modification method is not particularly limited, and a method of heating the resin to a melting point or higher in the presence/absence of a peroxide and then melt-kneading the resin is generally employed. 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. In order to maintain the interfacial strength with cellulose, the lower limit or more is preferable; in order to maintain the mechanical properties of the acid-modified polyolefin, the upper limit is preferably not more than the upper limit.

In order to improve the affinity with the cellulose interface, it is preferable that the Melt Flow Rate (MFR) of the acid-modified polypropylene measured at 230 ℃ under a load of 2.16kgf according to ISO1133 is 50g/10 min or more. 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, but 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 a polycondensation reaction 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 (polyamide 6, T/6, I, for example).

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 in 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 from the viewpoint of dispersibility in the cellulose particles; the ratio of the carboxyl end groups is preferably 0.95 or less in view of the color tone of the resin composition obtained.

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 monool to a polymerization solution 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 requires at least 300 scans when measured with equipment having 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 minimize the influence of additives, lubricants and the like to be mixed, it is more preferable to use¹H-NMR was used for the quantification.

The viscosity number [ VN ] of the polyamide resin measured in concentrated sulfuric acid at 30 ℃ is preferably 60 to 200mL/g, more preferably 70 to 180mL/g, still more preferably 70 to 140mL/g, and particularly preferably 70 to 120 mL/g. The polyamide resin having an intrinsic viscosity within the above range is advantageous in that, when a molded article is produced by injection molding of the resin composition, the in-mold flowability is improved and the appearance of the molded article is improved.

The "viscosity number" in the present disclosure is an indicator of the viscosity determined in 96% strength sulfuric acid according to ISO 307.

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 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 from the viewpoint of dispersibility of cellulose in the pellet; the ratio of the carboxyl end groups is preferably 0.95 or less in view of the color tone of the obtained 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%, particularly preferably 0.2 mol%. The upper limit amount is more preferably 3.5 mol%, still more preferably 3 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.

Examples of the vinyl resin preferable AS the thermoplastic resin include vinyl aliphatic (co) polymers (polyvinyl chloride, vinyl chloride-ethylene copolymers, ethylene-vinyl acetate copolymers (these may be olefin resins) and saponified products thereof), vinyl aromatic (co) polymers (polystyrene, block copolymers of conjugated dienes and vinyl aromatic hydrocarbons, hydrogenated products of block copolymers of conjugated dienes and vinyl aromatic hydrocarbons, and the like), acrylic (co) polymers (poly (meth) acrylates and the like), acrylonitrile (co) polymers (acrylonitrile-butadiene-styrene (ABS) resins, acrylonitrile-styrene (AS) resins, and the like).

Cellulose nanofiber

The fiber diameter of the cellulose nanofibers is preferably 50nm or more, or 60nm or more, or 70nm or more, from the viewpoint of improving the dispersibility of the cellulose nanofibers in the pellets or the molded article; in one embodiment, the fiber diameter is 1000nm or less, preferably 600nm or less, or 400nm or less, or 200nm or less, from the viewpoint of obtaining the physical property improving effect which the cellulose nanofibers impart to the molded article favorably. The fiber diameter is a value obtained 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 fiber diameter can be measured by the following method. Cellulose nanofibers were made into a solid content of 40 mass%, and kneaded in a planetary mixer (for example, manufactured by Kagaku Kogyo Co., Ltd., 5DM-03-R, stirring blade of hook type) at 126rpm for 30 minutes at room temperature and normal pressure, followed by preparing a pure water suspension at a concentration of 0.5 mass%, dispersing at 15,000rpm 5 minutes using a high shear Homogenizer (for example, manufactured by Nippon Seiko Co., Ltd., trade name, "EXCEL Auto Homogenizer ED-7" treatment condition), and separating by using a centrifugal separator (for example, manufactured by Kubota Seisakusho Co., Ltd., trade name "6800 Type centrifugal separator", Rotor Type RA-400 Type) under a centrifugal force of 39200m²Centrifugation 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 liquid was used to determine, as a volume average particle diameter, an integral 50% particle diameter (i.e., a sphere-equivalent diameter of the particle at an integral volume of 50% relative to the volume of the entire particle) in a volume frequency particle size distribution obtained by a laser diffraction/scattering method particle size distribution meter (for example, horiba, ltd., trade name "LA-910" or trade name "LA-950", ultrasonic treatment for 1 minute, refractive index 1.20).

In one embodiment, the L/D ratio of the cellulose nanofibers is 30 or more, or 40 or more, or 50 or more, or 100 or more. The upper limit is not particularly limited, and in one embodiment, 10000 or less in terms of handling property. In order to exhibit good mechanical properties of a molded article produced using the pellets 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) and diameter (D) of each of the cellulose nanofibers, and cellulose nanocrystals and cellulose microfibers (hereinafter also referred to as cellulose components) as optional additional components, and the L/D ratio calculated therefrom, can be determined by dispersing an aqueous dispersion of the cellulose components using a high shear Homogenizer (for example, product name "EXCEL Auto Homogenizer ED-7" manufactured by japan seiko corporation) 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 the aqueous dispersion on mica, air-drying the aqueous dispersion to prepare a measurement sample, and measuring the measurement sample using 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 components are observed, the length (L) and the diameter (D) of 100 cellulose components selected at random are measured, and the (L/D) ratio is calculated. The number average of the above 100 celluloses was defined as length (L), diameter (D) and (L/D) ratio.

The cellulose nanofibers may be cellulose obtained by: the cellulose is obtained by treating pulp or the like with hot water or the like at 100 ℃ or higher to partially hydrolyze and embrittle hemicellulose, and then opening the pulp by a pulverization method using a high-pressure homogenizer, a high-pressure microjet homogenizer, a ball mill, a disc pulverizer, or the like.

In one embodiment, the cellulose nanofibers may be modified (i.e., modified cellulose nanofibers). Examples of the modified cellulose nanofibers include cellulose modified with 1 or more modifying agents selected from the group consisting of esterification agents, silylation agents, isocyanate compounds, halogenated alkylation agents, oxyalkylene compounds and/or glycidyl compounds. In a preferred embodiment, the cellulose nanofibers are unmodified or modified without an oxoacid-modifying group (i.e., a site where the 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 includes an organic compound having at least one functional group capable of reacting with a hydroxyl group on the surface of the cellulose nanofiber to esterify the same. 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.

Preferred examples of the esterification agent are not particularly limited, and include, for example: 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 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 includes a Si-containing compound having at least one reactive group capable of reacting with a hydroxyl group on the surface of 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 includes 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 includes an organic compound having at least one isocyanate group capable of reacting with a hydroxyl group on the surface of cellulose. 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 include organic compounds having at least one oxyalkylene, glycidyl and/or epoxy group capable of reacting with a hydroxyl group on the surface of the cellulose. 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.

In one embodiment, the cellulose nanofibers are hydrophobized cellulose nanofibers. The above-exemplified modifiers can be preferably used for producing hydrophobized cellulose nanofibers. Among these, acetylated cellulose nanofibers are preferable as the hydrophobic cellulose fibers.

The content of the cellulose nanofibers in the pellets is preferably 0.1 mass% or more, more preferably 1 mass% or more, further preferably 3 mass% or more, and particularly preferably 5 mass% or more, from the viewpoint of favorably obtaining the physical property-improving effect that the cellulose nanofibers impart to the molded article, and is preferably 30 mass% or less, more preferably 20 mass% or less, and further preferably 10 mass% or less, from the viewpoint of favorably maintaining the dispersibility of the cellulose nanofibers in the pellets or the molded article, favorably obtaining the target physical property-improving effect by the cellulose nanofibers, and from the viewpoint of production cost.

Supplement component

The pellet may optionally contain an additional component in addition to the thermoplastic resin and the cellulose nanofibers. Examples of the additional component include cellulose nanocrystals, cellulose microfibrils, elastomers, surface treatment agents, compatibilizers, plasticizers, colorants, pigments, flow control agents, antioxidants, ultraviolet absorbers, ultraviolet dispersants, inorganic fillers, and lubricating oils. These components can be used in combination of 1 or 2 or more. In addition, these components may be reagents or products that are commercially available.

< cellulose nanocrystals and cellulose microfibrils >

In a preferred embodiment, the additional component comprises cellulose nanocrystals having a diameter of 100nm or less and an L/D of less than 30, or cellulose microfibrils having a fiber diameter of more than 1 μm and 50 μm or less, or a mixture thereof.

The diameter of the cellulose nanocrystal is 100nm or less, or 80nm or less, or 70nm or less in one embodiment, or 3nm or more, or 5nm or more, or 10nm or more in one embodiment. The L/D of the cellulose nanocrystal is less than 30, or 20 or less, or 15 or less, or 10 or less in one embodiment, and 1 or more, or 2 or more, or 4 or more, or 5 or more in one embodiment.

The fiber diameter of the cellulose microfibrils is greater than 1 μm, or 2 μm or more, or 5 μm or more, or 10 μm or more in one embodiment, and 50 μm or less, or 45 μm or less, or 40 μm or less, or 30 μm or less, or 20 μm or less, or 15 μm or less in one embodiment. The L/D of the cellulose microfibrils is 30 or more, or 50 or more, or 70 or more in one embodiment, or 2000 or less, or 1000 or less, or 500 or less in one embodiment.

In one embodiment, the cellulose nanocrystals and/or cellulose microfibrils may be a modification. Examples of modification may be the same as the above examples in the cellulose nanofibers.

< elastomer >

In the present disclosure, an elastomer refers to a substance that is an elastomer at room temperature (23 ℃), specifically, a natural or synthetic polymer substance. Specific examples of the elastomer include natural rubber, a conjugated diene compound polymer, an aromatic compound-conjugated diene copolymer, a hydrogenated product of an aromatic compound-conjugated diene copolymer, a polyolefin elastomer, a polyester elastomer, a polyurethane elastomer, a polyamide elastomer, and an elastomer having a core-shell structure. In one embodiment, the elastomer is a different type of polymer than the thermoplastic resin. Among these, for example, from the viewpoint of easiness of modification reaction for obtaining an elastomer having an acidic functional group described later, an aromatic compound-conjugated diene copolymer, a hydrogenated product of an aromatic compound-conjugated diene copolymer, a polyolefin elastomer, and an elastomer having a core-shell structure are preferable. Further, among the hydrogenated aromatic compound-conjugated diene copolymers and hydrogenated aromatic compound-conjugated diene copolymers, hydrogenated aromatic compound-conjugated diene block copolymers and hydrogenated aromatic compound-conjugated diene block copolymers are more preferable, and among the polyolefin elastomers, copolymers of ethylene and α -olefins are more preferable.

The aromatic compound-conjugated diene block copolymer referred to herein is a block copolymer composed of a polymer block (a) mainly composed of an aromatic vinyl compound and a polymer block (B) mainly composed of a conjugated diene compound. From the viewpoint of exhibiting impact strength, a block copolymer in which the bonding form of each block is any of AB type, ABA type, and ABAB type is preferable, and the bonding form is more preferably ABA type or ABAB type.

The mass ratio of the aromatic vinyl compound to the conjugated diene compound in the block copolymer is preferably 10/90 to 70/30. More preferably 15/85-55/45, and most preferably 20/80-45/55. Further, they may be a blend of 2 or more species having different mass ratios of the aromatic vinyl compound and the conjugated diene compound. Specific examples of the aromatic vinyl compound include styrene, α -methylstyrene, and vinyltoluene, and 1 or more compounds selected from these can be used, with styrene being particularly preferred.

Specific examples of the conjugated diene compound include butadiene, isoprene, piperylene, 1, 3-pentadiene, and the like, and 1 or more compounds selected from these can be used, and among them, butadiene, isoprene, and a combination thereof are preferable. When butadiene is used as the conjugated diene compound of the block copolymer, the 1, 2-vinyl content or the total amount of the 1, 2-vinyl content and the 3, 4-vinyl content is preferably 5 to 80%, more preferably 10 to 50%, and most preferably 15 to 40% on a molar basis, as the microstructure of the polybutadiene block portion, from the viewpoint of suppressing crystallization of the soft segment.

The hydrogenated product of the block copolymer of the aromatic vinyl compound and the conjugated diene compound is a component in which the aliphatic double bond of the polymer block mainly composed of the diene compound is controlled to be in a range of more than 0% to 100% by hydrogenating the block copolymer of the aromatic vinyl compound and the conjugated diene compound. The hydrogenation ratio of the hydrogenated product of the block copolymer is preferably 50% or more, more preferably 80% or more, and most preferably 98% or more, from the viewpoint of suppressing thermal degradation during processing.

The molecular weight of the block copolymer of the aromatic vinyl compound and the conjugated diene compound and the hydrogenated product thereof is preferably 10,000 to 500,000, and more preferably 40,000 to 250,000 in terms of both impact strength and fluidity. The number average molecular weight referred to herein is a value obtained by measuring chloroform as an elution solvent by a GPC apparatus at a measurement temperature of 40 ℃ and converting the molecular weight into a polystyrene standard polymer.

In these aromatic vinyl compound-conjugated diene compound block copolymers, 2 or more components having different bonding forms, components having different molecular weights, components having different types of aromatic vinyl compounds, components having different types of conjugated diene compounds, components having different 1, 2-vinyl contents or total amounts of 1, 2-vinyl contents and 3, 4-vinyl contents, components having different aromatic vinyl compound component contents, components having different hydrogenation rates, and the like can be mixed and used.

In addition, as the polyolefin-based elastomer, an ethylene- α -olefin copolymer can be preferably used in terms of expression of impact resistance. Examples of the monomer copolymerizable with the ethylene unit include aliphatic substituted vinyl monomers such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, or 1-eicosene, isobutylene, aromatic vinyl monomers such as styrene and substituted styrene, ester vinyl monomers such as vinyl acetate, acrylic acid ester, methacrylic acid ester, glycidyl acrylate, glycidyl methacrylate, hydroxyethyl methacrylate, etc., ester vinyl monomers such as ethylene, vinyl acetate, vinyl methacrylate, vinyl acetate, hydroxyethyl methacrylate, etc., vinyl acetate, nitrogen-containing vinyl monomers such as acrylamide, allylamine, vinylphenylamine, and acrylonitrile, and dienes such as butadiene, cyclopentadiene, 1, 4-hexadiene, and isoprene.

The copolymer is preferably a copolymer of ethylene and 1 or more alpha-olefins having 3 to 20 carbon atoms, more preferably a copolymer of ethylene and 1 or more alpha-olefins having 3 to 16 carbon atoms, and most preferably a copolymer of ethylene and 1 or more alpha-olefins having 3 to 12 carbon atoms. The molecular weight of the ethylene- α -olefin copolymer is preferably 10,000 or more, more preferably 10,000 to 100,000, and even more preferably 20,000 to 60,000 in number average molecular weight (Mn) measured by a gel permeation chromatography measuring apparatus using 1,2, 4-trichlorobenzene as a solvent at 140 ℃ using a polystyrene standard sample, from the viewpoint of exhibiting impact resistance. Further, from the viewpoint of satisfying both the fluidity and the impact resistance, the molecular weight distribution (weight average molecular weight/number average molecular weight: Mw/Mn) is preferably 3 or less, and more preferably 1.8 to 2.7.

In addition, from the viewpoint of handling properties during processing, the ethylene- α -olefin copolymer preferably contains 30 to 95 mass% of ethylene units based on the total amount of the ethylene- α -olefin copolymer.

These preferable ethylene- α -olefin copolymers can be produced by the production methods described in, for example, JP-B-4-12283, JP-A-60-35006, JP-A-60-35007, JP-A-60-35008, JP-A-5-155930, JP-A-3-163088 and U.S. Pat. No. 5272236.

In the present disclosure, as the elastomer having a core-shell structure, there can be mentioned a core-shell type impact modifier having a core which is a particulate rubber and a shell which is a glassy graft layer formed outside the core. As the rubber component as the core, butadiene-based rubber, acrylic rubber, silicone-acrylic composite rubber, and the like can be preferably used. In addition, a glassy polymer such as a styrene resin, an acrylonitrile-styrene copolymer, and an acrylic resin can be preferably used for the shell. For example, when the thermoplastic resin is a polyamide resin, an elastomer having a core-shell structure including a core of butadiene rubber and a shell of an acrylic resin can be preferably used from the viewpoint of compatibility with the polyamide.

In one embodiment of the elastomer, at least a part of the elastomer has an acidic functional group. In the present disclosure, the elastomer having an acidic functional group means that the acidic functional group is added through a chemical bond in the molecular skeleton of the elastomer. In the present disclosure, the acidic functional group means a functional group capable of reacting with a basic functional group or the like, and specific examples thereof include a hydroxyl group, a carboxyl group, a carboxylate group, a sulfo group, an acid anhydride group, and the like. When at least a part of the elastomer has an acidic functional group, the elastomer is preferably high in affinity with the cellulose nanofibers.

When the elastomer has an acidic functional group, the amount of the acidic functional group added to the elastomer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, based on 100% by mass of the elastomer, from the viewpoint of affinity with the cellulose nanofibers. The number of acidic functional groups is a value obtained as follows: the number of the acidic functional groups is obtained by measuring a sample for a calibration curve prepared by mixing an acidic substance in advance with an infrared absorption spectrum measuring apparatus and measuring the sample based on a calibration curve prepared using a characteristic absorption band of an acid.

Examples of the elastomer having an acidic functional group include an elastomer having a core-shell structure having a shell formed of a layer formed using acrylic acid or the like as a copolymerization component; an elastomer which is a modified product obtained by grafting an α, β -unsaturated dicarboxylic acid or a derivative thereof to a hydrogenated product of an ethylene- α -olefin copolymer, a polyolefin, an aromatic compound-conjugated diene copolymer, or an aromatic compound-conjugated diene copolymer containing acrylic acid or the like as a monomer, in the presence or absence of a peroxide.

In a preferred mode, the elastomer is an anhydride-modified elastomer.

Among these, a modified product obtained by grafting an α, β -unsaturated dicarboxylic acid or a derivative thereof onto a polyolefin elastomer, an aromatic compound-conjugated diene copolymer, or a hydrogenated product of an aromatic compound-conjugated diene copolymer in the presence or absence of a peroxide is more preferable, and a modified product obtained by grafting an α, β -unsaturated dicarboxylic acid or a derivative thereof onto an ethylene- α -olefin copolymer or a hydrogenated product of an aromatic compound-conjugated diene block copolymer in the presence or absence of a peroxide is particularly preferable.

Specific examples of the α, β -unsaturated dicarboxylic acid and its derivative include maleic acid, fumaric acid, maleic anhydride, and fumaric anhydride, and among these, maleic anhydride is particularly preferable.

When the elastomer has an acidic functional group, the elastomer may be a mixture of an elastomer having an acidic functional group and an elastomer having no acidic functional group. The mixing ratio of the elastomer having an acidic functional group and the elastomer having no acidic functional group is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and most preferably 40% by mass or more, when the total of both is 100% by mass, from the viewpoint of maintaining high toughness and physical stability of the resin composition. The upper limit is not particularly limited, and an elastomer having an acidic functional group in substantially all of the elastomers may be used, but from the viewpoint of not causing a problem in fluidity, it is preferably 80% by mass or less.

In the resin composition, the amount of the elastomer is preferably in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the thermoplastic resin. The upper limit is more preferably 40 parts by mass, still more preferably 35 parts by mass, yet more preferably 30 parts by mass, and most preferably 25 parts by mass. In order to maintain the rigidity and heat resistance of the resin composition well, the upper limit is preferably not more than the above-mentioned upper limit. The lower limit is more preferably 2 parts by mass, still more preferably 3 parts by mass, still more preferably 4 parts by mass, and most preferably 5 parts by mass. The lower limit or more is preferable for improving the toughness and physical property stability of the resin composition.

The dispersion particle diameter of the elastomer phase when it forms a particulate dispersed phase (dispersion particles) in the resin composition is preferably 3 μm or less, more preferably 2 μm or less, and most preferably 1 μm or less in terms of number average particle diameter. The lower limit is not particularly limited, but is, for example, 0.1. mu.m. From the viewpoint of high toughness and stability of physical properties, the above range is preferable.

The elastomer preferably has high uniformity of dispersed particle size. From this point of view, the volume ratio of the dispersed particles having a particle diameter of 1 μm or more to the entire dispersed particles of the elastomer is preferably 30 vol% or less. The upper limit is more preferably 25 vol%, still more preferably 20 vol%, still more preferably 15 vol%, and most preferably 10 vol%. In the volume-based dispersed particle size distribution, the presence of coarse particles, even if the amount is extremely small, immediately shows that the volume ratio of dispersed particles having a particle size of 1 μm or more is increased. When the volume ratio is within the above range, the uniformity of the dispersed particle size is high, which is preferable. The volume ratio may be, for example, 2 vol% or more, or 5 vol% or more, from the viewpoint of ease of production of the resin composition.

Examples of methods for improving the uniformity of the dispersed particle diameter of the elastomer include: a method of producing a resin composition by extrusion-kneading compounding ingredients of the resin composition, and finely dispersing an elastomer by increasing a screw rotation speed at the time of extrusion-kneading to impart a high shear stress to the compounding ingredients; a method of providing a tensile flow strain to a compounded component by disposing a screw member having a uniform narrow gap such as a seal ring; a method of passing a molten polymer through a special narrow slit and applying a tensile flow strain to the molten polymer by the slit portion; and the like, but when a method of imparting high shear is used, the polymer temperature is significantly increased at the time of processing, and therefore a method using a tensile flow strain is more preferable.

Examples of the method for observing the dispersion form include: a method in which a resin composition in the form of a molded article, a pellet, or the like is cut into an ultrathin section, a thermoplastic resin phase is dyed with phosphotungstic acid or the like, and then observation is performed with a transmission electron microscope; a method in which the surface of a resin composition having a shape of a molded body, a pellet, or the like is uniformly finished, and then the resin composition is immersed in a solvent in which only an elastomer is selectively dissolved, and the elastomer is extracted and observed with a scanning electron microscope; and so on. The obtained image is binarized by an image analyzer, the diameters of dispersed particles (at least 500 randomly selected) of the dispersed phase are calculated as equivalent circle diameters, and the respective particle diameters are counted, whereby the volume ratio of particles having a number average particle diameter of the dispersed particles and a specific particle diameter (for example, the above particle diameter of 1 μm or more) can be calculated.

< surface treating agent >

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 1 or more kinds of 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 pellet is preferably 0.1 mass% or more, or 0.2 mass% or more, or 0.5 mass% or more from the viewpoint of improving the dispersibility of the cellulose nanofibers in the pellet, and is preferably 50 mass% or less, or 30 mass% or less, or 20 mass% or less, or 18 mass% or less, or 15 mass% or less, or 10 mass% or less, or 5 mass% or less from the viewpoint of suppressing the plasticization of the molded body and maintaining the strength well.

The preferable amount of the surface treatment agent is preferably 0.1 part by mass or more, or 0.5 part by mass or more, or 1 part by mass or more with respect to 100 parts by mass of the cellulose nanofibers, 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 plasticization of the molded body and maintaining strength well.

< antioxidant >

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, based on the whole pellet.

< inorganic Filler >

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. The amount of the inorganic filler in the pellets is preferably 0.002 to 50 parts by mass per 100 parts by mass of the thermoplastic resin, from the viewpoint of improving handling properties when molding the pellets into a molded article.

< lubricating oil >

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, or 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 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 per 100 parts by mass of the thermoplastic resin, 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, from the viewpoint of avoiding undesirable softening of the molded article, from the viewpoint of improving wear resistance.

The total amount of the additional components in the pellet may be, for example, 0.01 mass% or more, or 0.1 mass% or more, or 1 mass% or more, or may be, for example, 20 mass% or less, or 10 mass% or less, or 5 mass% or less.

In a preferred embodiment, the pellet contains 50 to 99 mass% of the thermoplastic resin, 1 to 30 mass% of the cellulose nanofibers, and 0.01 to 20 mass% of the additional component. In another preferred embodiment, the pellet comprises 70 to 99 mass% of the thermoplastic resin, 1 to 10 mass% of the cellulose nanofibers, and 0.01 to 30 mass% of the additional component; or 75 to 99 mass% of a thermoplastic resin, 1 to 5 mass% of a cellulose nanofiber, and 0.01 to 20 mass% of an additional component.

< agent for reducing crystallization temperature of resin >

The crystallization temperature depressant of the present disclosure is a compound that lowers the temperature-lowered crystallization peak temperature of the resin composition of the present disclosure measured by a Differential Scanning Calorimeter (DSC) by 5 to 30 ℃ (i.e., the resin composition containing the crystallization temperature depressant has a temperature-lowered crystallization peak temperature that is 5 to 30 ℃ lower than that of the same resin composition except that the crystallization temperature depressant is not contained). The lowering of the crystallization peak temperature by the crystallization temperature lowering agent is preferably 5 to 25 ℃ or 10 to 20 ℃. The crystallization peak temperature at a reduced temperature in the present disclosure is a peak top temperature of a crystallization peak at a temperature reduced by 10 ℃/min after the temperature is increased to a melting point +30 ℃ (when the thermoplastic resin is a crystalline resin) and a glass transition point +30 ℃ (when the thermoplastic resin is an amorphous resin) at a temperature increase rate of 10 ℃/min by DSC. When pellets of the resin composition are produced by melt-mixing the thermoplastic resin and the cellulose nanofibers and then cooling the mixture using the crystallization temperature depressant, crystallization of the resin composition by cooling can be gradually progressed, and voids in the pellets can be reduced.

Examples of the crystallization temperature reducing agent include pentaerythritol, dipentaerythritol, trimethylolethane, and nigrosine, and pentaerythritol is particularly preferable.

The mass ratio of the crystallization temperature depressant to 100 mass% of the resin composition is preferably 0.01 to 10 mass%, or 0.05 to 5 mass%, or 0.8 to 3 mass%.

[ Properties of resin composition ]

In one embodiment, the difference Tcc-Tcp between the reduced temperature crystallization peak temperature Tcc of the resin composition and the reduced temperature crystallization peak temperature Tcp of the thermoplastic resin contained in the resin composition (peak temperature on the highest temperature side in the case where two or more thermoplastic resins having different reduced temperature crystallization peak temperatures are present) is preferably 5 to 30 ℃, or 5 to 25 ℃, or 10 to 20 ℃. In the case of producing pellets of a resin composition in which Tcc-Tcp is in the above range by melt-mixing a thermoplastic resin and cellulose nanofibers and then cooling the mixture, the resin composition tends to be easily crystallized by cooling the resin composition.

In one embodiment, the ratio Ve/Vc of the void (Ve) in each of 100 pellets to the total volume (Vc) of the cellulose nanofibers is preferably 0 to 4 vol%, or 0 to 3 vol%, or 0 to 1 vol%, from the viewpoint of obtaining pellets with less void generation than the amount of the cellulose nanofibers. Ve/Vc is calculated by the following equation.

Ve/Vc ═ 100 (void area ratio × void-containing pellet ratio)/(cellulose volume ratio in the absence of voids × (100-void area ratio × void-containing pellet ratio/100)) × 100

The volume ratio of the cellulose in the case where no void exists was calculated from the addition amounts and the densities of the respective components of the resin composition.

[ production of pellets ]

The pellets of the present disclosure can be produced, for example, by the following method: the thermoplastic resin, the cellulose nanofibers, and optional additional components are melt-kneaded using a single-screw or twin-screw extruder, extruded into a strand-like form, and cooled and solidified in a water bath to obtain pellets. The thermoplastic resin, the cellulose nanofibers, and optional additional components are melt-kneaded by the following method.

(1) A method of melt-kneading a thermoplastic resin, cellulose nanofibers and optionally additional components together.

(2) A method comprising melt-kneading a thermoplastic resin and, if necessary, an optional additional component, and then adding the cellulose nanofibers and, if necessary, an optional additional component, followed by further melt-kneading.

(3) A method in which a thermoplastic resin, cellulose nanofibers and optional additional components are melt-kneaded, and then the cellulose nanofibers, water and optional additional components, if necessary, are mixed, followed by melt-kneading all together.

(4) A method of melt-kneading a thermoplastic resin and, if necessary, an optional additional component, and then adding the thermoplastic resin and the cellulose nanofibers mixed in a desired ratio, and the optional additional component, and further melt-kneading them.

(5) A method of adding the above (1) to (4) in a manner such that they are divided into top feed and side feed at an arbitrary ratio by using a single-screw or twin-screw extruder, and melt kneading them.

In the extruder, properties of the pellets can be changed by controlling the melting temperature, the screw diameter, the resin discharge amount, the number of die holes, the die hole diameter, and the like, and controlling the air cooling distance from the extruder die to the strand bath water surface, the strand bath temperature, the strand bath immersion length, the strand drawing speed, and the like, which are conditions for cooling the strand discharged from the extruder. From the viewpoint of reducing the void-containing pellets, control of melt kneading temperature, control of resin discharge amount, control of the number of die holes, control of air cooling distance, control of strand bath temperature, and control of strand impregnation length are useful.

The design conditions of the extruder include the screw diameter, the number of die holes, and the die hole diameter. The cooling conditions for the strand discharged from the extruder include the air cooling distance from the extruder die to the water surface of the strand bath, the strand bath temperature, the strand bath immersion length, and the strand drawing speed.

The melt kneading temperature can be adjusted according to the type of the thermoplastic resin. Further, the cooling rate of the strands can be reduced by increasing the air cooling distance between the extruder die and the water surface of the strand bath, increasing the water temperature in the strand bath, and the like. For example, the melting temperature is set to the melting point of the crystalline thermoplastic resin or the glass transition point of the amorphous thermoplastic resin + (20 ℃ to 100 ℃) and the cooling rate of the strand is controlled, thereby increasing the time until the temperature of the resin composition is lowered from the melting temperature to a temperature lower than the melting point of the crystalline thermoplastic resin or the glass transition point of the amorphous thermoplastic resin when the strand is cooled.

For example, the conditions when the thermoplastic resin is an aliphatic polyamide resin include a melt kneading temperature of 180 to 300 ℃, a strand cooling condition of 150 to 300mm air cooling distance, a strand bath temperature of 40 ℃, and an impregnation length of 300 to 500 mm.

Further, the conditions when the thermoplastic resin is a polypropylene resin include a melt kneading temperature of 180 to 250 ℃, a strand cooling condition of 150 to 300mm air cooling distance, a strand bath temperature of 40 ℃, and an impregnation length of 500 to 2000 mm.

The cooled strands were cut into pellet shapes. The shape of the pellets may vary depending on the cutting method in the extrusion processing, and for example, most of the pellets cut by a cutting method called underwater cutting are spherical, most of the pellets cut by a cutting method called thermal cutting are spherical or ellipsoidal, and most of the pellets cut by a cutting method called strand cutting are cylindrical.

[ use of pellets and Process for producing molded article ]

The pellets of the present embodiment can be used in various molding methods such as extrusion molding (cold runner system, hot runner system), injection molding, injection extrusion molding, gas-assisted injection molding, foam injection molding, ultra-thin wall injection molding (ultra-high speed injection molding), and the like, vacuum molding, blow molding, decorative molding, heterogeneous material molding, low pressure molding, in-mold composite molding (insert molding, insert-on molding), and the like to produce molded articles. In injection molding, the advantages resulting from the use of the pellets of the present disclosure may be particularly pronounced.

In one embodiment of the present invention, there is provided a method for producing a molded article, comprising a step of preparing the pellet of the present disclosure, and a step of obtaining a molded article by injection molding the pellet in a mold. From the viewpoint of the particularly remarkable advantage of reducing yellowing and appearance defects of a molded article by using the pellets of the present disclosure, a hydraulic, electric, or hydraulic-electric hybrid injection molding machine can be exemplified as a preferred injection molding machine as a driving method; examples of the injection structure include a ram type, a preplasticizing type, and a screw type injection molding machine. From the above points, preferable molding conditions include a melting temperature of the melting point of the crystalline thermoplastic resin or the glass transition point of the amorphous thermoplastic resin + (20 to 100 ℃) and a mold temperature of the melting point of the crystalline thermoplastic resin or the glass transition point of the amorphous thermoplastic resin- (50 to 200 ℃).

The molded article can be provided in various shapes such as a sheet, a film, a fiber, and various solid or hollow molded articles. The molded article can be used in various applications, for example, industrial machine parts (e.g., electromagnetic device housings, roller materials, transmission arms, medical device parts, etc.), general machine parts, parts of automobiles, railways, vehicles, etc. (e.g., outer plates, chassis, aerodynamic parts, seats, friction materials in transmissions), marine parts (e.g., hulls, seats, etc.), aviation-related parts (e.g., bodies, main paddles, tail paddles, movable paddles, cowlings, fairings, hatches, seats, interior materials, etc.), spacecraft, satellite parts (motor housings, main paddles, bodies, antennas, etc.), electronic-electric parts (e.g., personal computer housings, cellular phone housings, OA devices, AV devices, telephones, facsimiles, home appliances, toy products, etc.), building-civil engineering materials (e.g., reinforcing-bar-substituting materials), and the like, Truss structures, cables for suspension bridges, and the like), articles for daily use, sports-leisure articles (for example, golf club shafts, fishing rods, tennis or badminton rackets, and the like), housing members for wind power generation, and the like, container-packaging members, and high-pressure containers for filling hydrogen gas and the like used in fuel cells, for example.

Further, when the molded article is provided in the form of a resin composite film, it is suitable for use in reinforcing a laminate in a printed wiring board. Further, the present invention can be applied to applications such as an insulating cylinder in a generator, a transformer, a rectifier, a circuit breaker, a controller, an insulating handle, an arc extinguishing plate, an operation lever, an insulating partition, a housing, a wind tunnel, a socket, a fan blade, a switch box in a standard electric appliance, a housing, a cross-over switch, an insulating shaft, a fan blade, a mechanism part, a transparent resin substrate, a speaker diaphragm, a high-frequency speaker diaphragm, a television screen, a fluorescent lamp cover, an antenna in communication equipment/aerospace applications, a horn cover, a radome, a housing, a mechanical part, a wiring substrate, an aircraft, a rocket, an electronic device part for a satellite, a part for a railroad, a part for a ship, a bathtub, a septic tank, a corrosion resistant device, a chair, a helmet, a pipe, a tank car, a cooling tower, a floating breakwater, an underground tank, a container, and the like.

Among these, automobile parts and electronic parts requiring resin molding are preferable because superior properties due to excellent heat resistance of molded articles containing cellulose nanofibers can be exhibited.

Examples

The present embodiment will be specifically described below with reference to 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.

[ evaluation method ]

< temperature-decreasing crystallization Peak temperature of thermoplastic resin and resin composition >

The measurement was carried out by the following method.

The device comprises the following steps: differential scanning calorimeter (PERKINELMER DSC8500)

Conditions are as follows: disc: aluminium

Carrier gas: nitrogen (50 ml/min)

Temperature program: 20 ℃→ 250 ℃ (100 ℃/min)

250 deg.C (keep 5 minutes)

250 ℃→ 20 ℃ (10 ℃/min)

< ratio of total volume of pores per 100 pellets (Ve) to total volume of cellulose nanofibers (Vc) >

Calculated according to the following formula.

Ve/Vc ═ 100 (void area ratio × void-containing pellet ratio)/(cellulose volume ratio in the absence of voids × (100-void area ratio × void-containing pellet ratio/100)) × 100

The pore area ratio and the ratio of the pore-containing granules were measured by the methods described later.

The volume ratio of the cellulose in the case where no void exists was calculated from the addition amounts and the densities of the respective components of the resin composition. At this time, the density was calculated as: polyamide 6(PA6)1.14g/cm ³0.90g/cm of polypropylene (PP)³Maleic anhydride-modified ethylene-octene copolymer (MEOR)0.87g/cm³Cellulose Nanocrystals (CNC) and Cellulose Nanofibers (CNF)1.50g/cm³1.43g/cm of hydrophobized cellulose nanofiber (hydrophobized CNF)³Pentaerythritol (PET)1.40g/cm³。

< number of void-containing pellets per 100 pellets (void-containing pellet ratio) >

100 randomly selected pellets were cut at the center in the MD direction of the pellet, and flattened by a microtome (HM 340, Thermo Fisher Scientific Co., Ltd.) to obtain a TD cross section. The morphological image of the TD cross section was taken with a microscope (VHX-5000, manufactured by Yonzhi, K.K.) at a magnification of 20 times (observation field: 10 mm. times.14 mm), and the pellet having a recognizable pore was determined as a pore-containing pellet. The number of the void-containing pellets out of 100 pellets was counted as a void-containing pellet ratio.

< ratio of void area in void-containing pellet to cross-sectional area of TD cross-section of pellet (void area ratio) >

Selection of 100 pellets and morphological observation of TD cross section were performed by the same method as the above evaluation of < number of void-containing pellets per 100 pellets >. The void area of the particulate material containing voids at the TD cross section was measured by the software attached to the microscope, and the ratio of the void area to the total cross-sectional area of the TD cross section was calculated as 100%, and the average value of the particulate material containing voids in the whole was defined as the void area ratio. When 1 pellet containing pores out of 100 pellets was not included, the ratio of the pore area was 0%.

< Angle formed by the Normal line of the pellet section with respect to the MD of the pellet (pellet section inclination Angle) >

Each of the randomly selected 10 pellets was cut in a visually selected direction so as to pass through the center of the pellet TD and so as to maximize the inclination angle of the pellet cross section described later, and further flattened by a microtome (HM 340, manufactured by Thermo Fisher Scientific corporation) to obtain an MD cross section. The morphological image of the MD section was taken with a microscope (VHX-5000, Kiyoji, K.K.) at a magnification of 20 times (observation field: 10 mm. times.14 mm). The MD direction axis of the pellet and the normal line to the line segment corresponding to the MD direction end face of the pellet are defined on the morphological image, and the angle formed by the MD direction axis of the pellet and the normal line is measured. The number average of 10 pellets was obtained as the pellet section inclination angle.

< appearance of molded article >

The pellets were injection molded into the shape of a multipurpose test piece of ISO 294-3. The surfaces of the 30 multi-purpose test pieces thus produced were visually observed and evaluated according to the following criteria.

Good: the number of the silver lines generated is 0

And (4) qualification: the number of the silver streaks generated is more than 1 and less than 10

Poor: the number of the silver streaks generated is more than 10

< Molding cycle >

The pellets were injection molded into the shape of a multipurpose test piece of ISO 294-3. The average value of the molding cycle (seconds) at the time of producing 30 sheets was defined as the molding cycle.

< Yellowness (YI) >

The pellets were injection-molded into the shape of a multipurpose test piece of ISO 294-3, and YI was measured in accordance with JIS K7373.

[ materials used ]

< thermoplastic resin >

Polyamide 6(PA6)

UBE Nylon 1013B (Yu Ming Kao Co., Ltd.)

The ratio of carboxyl end groups ([ COOH ]/[ all end groups ]) was 0.6

The Viscosity Number (VN) of the polyamide measured in 96% strength by mass sulfuric acid was 95

Polypropylene (PP)

NOVATEC PP MA1B(Japan Polypropylene Corporation)

MFR (230 ℃, 2.16kgf) ═ 21g/10 min

< elastomer >

Maleic anhydride modified ethylene-octene copolymer (MEOR)

Fusabond MN-493D(Dow-Dupont)

MFR (190 ℃, 2.16kgf) ═ 1.2g/10 min

Octene content 28 mass%

Melting point 55 deg.C (DSC method: heating rate 10 deg.C/min)

Maleic anhydride addition rate of 1.0% by mass

< cellulose >

[ preparation example 1] cellulose nanocrystals (hereinafter referred to as CNC)

A commercially available DP pulp (average degree of polymerization 1600) was sheared and hydrolyzed in a 10 mass% aqueous hydrochloric acid solution at 105 ℃ for 30 minutes. The obtained acid-insoluble residue was filtered, washed, and pH-adjusted to prepare a crystalline cellulose dispersion having a solid content of 14 mass% and a pH of 6.5. The crystalline cellulose dispersion was spray-dried to obtain a dried crystalline cellulose. Then, the dried product obtained above was supplied to a jet mill (STJ-400 type, manufactured by Seishin Enterprise) at a supply rate of 10kg/hr, and the resulting product was pulverized to obtain CNC in the form of fine crystalline cellulose powder.

The obtained CNC was evaluated for characteristics, and as a result, the diameter was 30nm and the L/D was 8.

To the obtained CNC aqueous dispersion, 5 parts by mass of polyethylene glycol having a molecular weight of 20,000 (hereinafter, referred to as PEG20000) was added with respect to 100 parts by mass of CNC, and then vacuum drying was performed at about 40 ℃ using a revolution-rotation type stirrer (V-mini 300 manufactured by EME corporation), thereby obtaining CNC powder.

Production example 2 cellulose nanofiber (hereinafter referred to as CNF)

The linter pulp was sheared, heated in hot water at 120 ℃ or higher for 3 hours in an autoclave, the purified pulp from which the hemicellulose fraction was removed was pressed, and highly short-staple and fibrillated by beating so that the solid content ratio in pure water was 1.5 mass%, and then defibrated at that concentration in a high-pressure homogenizer (10 times treatment at an operating pressure: 85 MPa), to obtain defibrated cellulose. In the beating process, a disc refiner was used to perform a 4-hour process using a beating blade having a high cutting function (hereinafter referred to as a cutting blade), and then beating was further performed for 1.5 hours using a beating blade having a high defibrating function (hereinafter referred to as a defibrating blade).

The characteristics of the obtained CNF were evaluated, and as a result, the diameter was 90nm and the L/D was 30 or more (about 300).

To the obtained water dispersion of CNF, 5 parts by mass of PEG20000 was added per 100 parts by mass of CNF, and then vacuum-dried at about 40 ℃ using a revolution-rotation type stirrer (V-mini 300 manufactured by EME corporation), thereby obtaining a CNF powder.

[ production example 3] hydrophobized CNF (hereinafter referred to as hydrophobized CNF)

(defibering Process)

As a raw material of the linter pulp, a single screw stirrer (DKV-1. phi. 125mm dissolver manufactured by IMEX Co.) was used to stir at 500rpm in dimethyl sulfoxide (DMSO) at room temperature for 1 hour. Subsequently, the resulting mixture was charged into a bead mill (NVM-1.5 manufactured by IMEX Co.) by a hose pump, and circulated only with DMSO for 120 minutes to obtain a defibrinated slurry.

(defibration-acetylation step)

Thereafter, 11 parts by mass of vinyl acetate and 1.63 parts by mass of sodium hydrogencarbonate were added to the bead mill apparatus per 100 parts by mass of the defibrinated slurry, and a circulation operation was further performed for 60 minutes to obtain a hydrophobized CNF slurry.

In the case of the circulation operation, the rotational speed of the bead mill was 2500rpm, and the peripheral speed was 12 m/s. As the beads, those having a particle diameter of 2.0mm made of zirconia were used, and the filling rate was 70% (in this case, the gap between the beads in the bead mill was 0.6 mm). In the circulation operation, the temperature of the slurry was controlled to 40 ℃ by a cooler so as to absorb heat generated by friction.

192 parts by mass of pure water per 100 parts by mass of the defibered slurry was added to the obtained hydrophobized CNF slurry, and after sufficiently stirring, the mixture was added to a dehydrator and concentrated. The obtained wet cake was dispersed again in the same amount of pure water, stirred and concentrated, and the cleaning operation was repeated 5 times in total.

The characteristics of the obtained hydrophobized CNF were evaluated, and as a result, the diameter was 65nm and the L/D was 30 or more (about 450).

To the obtained water dispersion of the hydrophobized CNF (solid content ratio: 10 mass%), 5 parts by mass of PEG20000 was added to 100 parts by mass of the hydrophobized CNF, and then vacuum-dried at about 40 ℃ using a revolution-rotation type stirrer (V-mini 300 manufactured by EME corporation), thereby obtaining a hydrophobized CNF powder.

< agent for reducing crystallization temperature of resin >

Pentaerythritol (PET) (Tokyo chemical industry Co., Ltd.)

CAS：115-77-5

[ example 1]

PA6(90 parts by mass) was mixed with the CNF (10 parts by mass) obtained in preparation example 2, and melt-kneaded at a kneading temperature of 250 ℃ using a twin-screw extruder (TOSHIBA MACHINE co., TEM-37SS manufactured by LTD, screw diameter 37mm), and extruded into a strand shape. At this time, the resin discharge amount of the twin-screw extruder was 20kg/h, and the number of holes of the die was 3. The distance from the die hole to the water surface of the strand bath was adjusted so that the air cooling distance from the die to the water surface was 150 mm. Thereafter, the resultant was cooled to an immersion length of 400mm by a strand bath in which the water temperature was adjusted to 40 ℃ and then cut by a strand cutter to obtain a pellet form.

Comparative example 1 and example 2

Pellets were obtained in the same manner as in example 1, except that the pellet production conditions were changed as shown in table 1.

Comparative examples 2 and 3, examples 3 to 7 and 9

Pellets were obtained in the same manner as in example 1 except that the twin-screw extruder was changed to TOSHIBA MACHINE CO., TEM-75SS manufactured by LTD, and screw diameter was changed to 75mm) and pellet manufacturing conditions were changed as shown in Table 1.

[ example 8]

Pellets were obtained in the same manner as in example 3 except that the conditions for producing pellets were changed as shown in table 1 and the drawing speed of the strand cutter was adjusted in the low speed direction so that the minor axis of the TD cross section of the pellet became the value shown in table 1.

[ example 10]

Pellets were obtained in the same manner as in example 3 except that PA6(70 parts by mass), MEOR (20 parts by mass), and CNF (10 parts by mass) were mixed and melt-kneaded, and the pellet production conditions were changed as shown in table 1.

[ example 11]

Pellets were obtained in the same manner as in example 3 except that PA6(90 parts by mass), CNC (5 parts by mass) obtained in preparation example 1, and CNF (5 parts by mass) obtained in preparation example 2 were mixed and melt-kneaded, and pellet production conditions were changed as shown in table 1.

[ examples 12 and 13]

Pellets were obtained in the same manner as in example 3, except that PA6(90 parts by mass) and the hydrophobized CNF (10 parts by mass) obtained in preparation example 3 were mixed and melt-kneaded, and the pellet production conditions were changed as shown in table 1.

[ example 14]

Pellets were obtained in the same manner as in example 3 except that PA6(89 parts by mass), PET (1 part by mass), and the hydrophobized CNF (10 parts by mass) obtained in preparation example 3 were mixed and melt-kneaded, and pellet production conditions were changed as shown in table 1.

Comparative example 4 and example 15

Pellets were produced in the same manner as in example 3, except that PP (90 parts by mass) and CNF (10 parts by mass) obtained in production example 2 were mixed and melt-kneaded at a kneading temperature of 200 ℃.

[ reference example 1]

Pellets were obtained in the same manner as in example 1, except that only Polyamide (PA) was melt-kneaded without using a cellulose aggregate in step 3.

The results are shown in Table 1.

From the results shown in table 1, in examples 1 to 15, the molded article had less yellowing and good appearance, even though it was a pellet containing cellulose nanofibers. For example, in examples 2, 6, 7, 11 and 12 in which the water temperature was relatively high and the curing speed of the thermoplastic resin was reduced, the proportion of the void-containing pellets was 0%, and the occurrence of voids was reduced to an extent comparable to that of reference example 1 in which no cellulose nanofibers were used, and good appearance comparable to that of reference example 1 in which no cellulose nanofibers were used was exhibited. Further, in example 8 in which the pellet size was increased and examples 10 and 15 in which the type of the thermoplastic resin was changed, molded articles having less yellowing and good appearance were obtained. In examples 12 and 13 in which the hydrophobized CNF was used, the molded article was particularly less yellowed. In example 14 in which the resin crystallization temperature lowering agent was added, a molded article having a short molding cycle and little yellowing was further obtained.

Industrial applicability

The pellet of the present invention is useful for producing a molded article having a good appearance and suppressed yellowing.

Description of the symbols

1,2,3 pellets

Cross section of S1, S2 pellets

L pellet MD Direction

Normal direction of L1, L2

Theta 1 and theta 2.