阅读说明：本技术 纤维状纤维素复合树脂及其制造方法 (Fibrous cellulose composite resin and method for producing same ) 是由 松末一紘 落合优 于 2019-10-28 设计创作，主要内容包括：本发明提供强度特别是弯曲模量优异并且不具有着色问题的纤维状纤维素复合树脂及其制造方法。纤维状纤维素复合树脂包含平均纤维宽度为0.1μm以上的微纤维纤维素和树脂以及多元酸盐类。并且,将原料纤维以平均纤维宽度保持在0.1μm以上的范围进行开纤,制成微纤维纤维素,将该微纤维纤维素和树脂以及多元酸盐类进行混炼,由此制造纤维状纤维素复合树脂。(The invention provides a fibrous cellulose composite resin which is excellent in strength, particularly flexural modulus, and which does not have a problem of coloration, and a method for producing the same. The fibrous cellulose composite resin contains microfibrillar cellulose having an average fiber width of 0.1 [ mu ] m or more, a resin, and a polyacid salt. Then, the raw material fiber is opened in a range in which the average fiber width is maintained at 0.1 μm or more to prepare microfibrillar cellulose, and the microfibrillar cellulose, the resin, and the polyacid salt are kneaded to produce a fibrous cellulose composite resin.)

1. A fibrous cellulose composite resin comprising microfibrillar cellulose having an average fiber width of 0.1 μm or more, a resin, and a polyacid salt.

2. The fibrous cellulose composite resin according to claim 1, wherein the microfibrillar cellulose has an average fiber length of 0.02 to 3.0mm and a fibrillation rate of 1.0 to 30%.

3. The fibrous cellulose composite resin according to claim 1 or 2, wherein the polybasic acid salt is at least one of a phthalate salt and a phthalate salt derivative.

4. The fibrous cellulose composite resin according to claim 3, wherein the phthalate salt is at least one selected from the group consisting of potassium hydrogen phthalate, sodium phthalate and ammonium phthalate.

5. The fibrous cellulose composite resin according to any one of claims 1 to 4, wherein the microfibrillar cellulose is modified by a part of the polyacid salt.

6. A process for producing a fibrous cellulose composite resin, characterized in that,

opening the raw material fiber in the range of average fiber width of 0.1 μm or more to obtain microfibril cellulose,

the microfibrillar cellulose is kneaded with a resin and a polyacid salt.

7. The fibrous cellulose composite resin according to claim 1, comprising maleic anhydride-modified polypropylene.

8. The fibrous cellulose composite resin according to claim 7, wherein the proportion of the maleic anhydride-modified polypropylene is 0.1 to 1000 parts by mass with respect to 100 parts by mass of the microfibrillar cellulose.

9. The fibrous cellulose composite resin according to claim 1, comprising at least one or more selected from the group consisting of a polybasic acid, a derivative of a polybasic acid, and a derivative of a salt of a polybasic acid.

10. The fibrous cellulose composite resin according to claim 9, wherein the microfibrillar cellulose is modified with any one of the polybasic acid, the derivative of the polybasic acid, and the derivative of the salt of the polybasic acid.

11. The fibrous cellulose composite resin according to claim 9, wherein the polybasic acid is phthalic acid, and the polybasic acid salt is a phthalate salt.

Technical Field

The present invention relates to a fibrous cellulose composite resin and a method for producing the same.

Background

In recent years, various proposals have been made to use Cellulose Nanofibers (CNF) as a reinforcing material for resins. However, cellulose nanofibers irreversibly aggregate due to intermolecular hydrogen bonds derived from hydroxyl groups of polysaccharides. Therefore, even when cellulose nanofibers are used as a reinforcing material for a resin, the reinforcing effect of the resin cannot be sufficiently exhibited due to poor dispersibility of the cellulose nanofibers in the resin.

For example, patent document 1 proposes a polyolefin resin composition characterized in that a resin mixture containing a cellulose nanofiber having an average thickness of 10 to 200nm and a polyolefin resin contains a terpene-phenol compound as a compatibilizer. This document teaches that the dispersibility of cellulose nanofibers is improved when terpene phenol is contained (see paragraph 0038, for example). However, even if terpene phenol is contained, it is doubtful whether the dispersibility of cellulose nanofibers is sufficiently improved, and it is also expected to propose a compatibilizer that can replace terpene phenol.

For example, patent document 2 proposes a method of obtaining a cellulose microfiber by esterifying cellulose with a dicarboxylic acid anhydride in the presence of an alkali catalyst or an acid catalyst. This document proposes that when a fluorene compound is introduced into the obtained cellulose microfiber, the affinity with an organic medium such as a resin can be improved. However, the method of this document uses an alkali catalyst or an acid catalyst, and the reaction conditions are severe, thereby causing a problem of coloring of cellulose fibers.

Further, for example, patent document 3 proposes a resin composition in which a modified olefin polymer is compounded with cellulose fibers having an average fiber diameter of 4 to 400 nm. In addition, for example, patent document 4 proposes a composition containing a polymer compound having a primary amino group, a polymer compound modified with maleic anhydride, a nano-sized microfibrillated plant fiber, and a polyolefin. Further, for example, patent document 5 proposes a resin composition containing a modified microfibrillated plant fiber which is decomposed to a nanometer order and esterified with alkyl succinic anhydride or alkenyl succinic anhydride, a thermoplastic resin, and an inorganic salt.

However, according to the findings of the present inventors, the dispersibility of the cellulose fibers cannot be made sufficient by any of the above methods, and the cellulose fibers do not form a three-dimensional network, and the reinforcing effect of the resin is not sufficient.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-79311

Patent document 2: japanese patent laid-open publication No. 2017-82188

Patent document 3: japanese patent No. 5433949

Patent document 4: japanese patent No. 5717643

Patent document 5: japanese patent No. 5757765

Disclosure of Invention

Problems to be solved by the invention

The main object to be solved by the present invention is to provide a fibrous cellulose composite resin which is excellent in strength, particularly flexural modulus, and which does not have a problem of coloration, and a method for producing the same.

Means for solving the problems

The present inventors carried out various treatments on cellulose nanofibers in order to solve the above problems, and found a method for kneading cellulose nanofibers and a resin. That is, as in the patent documents 1 to 5, on the premise that cellulose nanofibers are used, improvements of various materials mixed with the cellulose nanofibers have been repeated, and various attempts have been made to modify the cellulose nanofibers.

However, even when cellulose nanofibers are hydrophobically modified, the dispersibility thereof in a resin is insufficient, and it is difficult to form a three-dimensional network of cellulose nanofibers in the resin, and a resin composition having sufficient strength cannot be obtained, and an effect of sufficiently reinforcing the resin cannot be obtained.

However, in the course of this study, it was found that if the raw material fiber is microfibrillar cellulose, the dispersibility in the resin is good, and a three-dimensional network of microfibrillar cellulose is formed in the resin, whereby a sufficient reinforcing effect for the resin can be obtained. Further, on the premise of this finding, a fibrous cellulose composite resin and a method for producing the same are proposed in which the dispersibility of fibrous cellulose is further improved, the strength of the resin is improved, and the problem of coloration is solved. Specifically, the following means are provided.

In patent document 4, it is stated that "in the present invention, the average fiber diameter of the microfibrillated plant fiber is preferably 4nm to 50 μm". However, this document clearly assumes cellulose nanofibers, and it is difficult to assume these as microfibril cellulose, and since the average fiber diameter is too wide in the range of 4nm to 50 μm, it is difficult for the inventors not only to derive the fact that microfibril cellulose and the like are applied, but also to the general inventors based on this description.

(embodiment 1)

A fibrous cellulose composite resin comprising microfibrillar cellulose having an average fiber width of 0.1 μm or more, a resin, and a polyacid salt.

(embodiment 2)

The fibrous cellulose composite resin according to claim 1, wherein the microfibrillar cellulose has an average fiber length of 0.02 to 3.0mm and a fibrillation rate of 1.0 to 30%.

(embodiment 3)

The fibrous cellulose composite resin according to claim 1 or 2, wherein the polybasic acid salt is at least one of a phthalate salt and a phthalate salt derivative.

(embodiment 4)

The fibrous cellulose composite resin according to claim 3, wherein the phthalate salt is at least one selected from the group consisting of potassium hydrogen phthalate, sodium phthalate and ammonium phthalate.

(embodiment 5)

The fibrous cellulose composite resin according to any one of claims 1 to 4, wherein the microfibrillar cellulose is modified with a part of the polyacid salt.

(embodiment 6)

A process for producing a fibrous cellulose composite resin, characterized in that,

opening the raw material fiber in the range of average fiber width of 0.1 μm or more to obtain microfibril cellulose,

the microfibrillar cellulose is kneaded with a resin and a polyacid salt.

(embodiment 7)

The fibrous cellulose composite resin according to claim 1, which comprises maleic anhydride-modified polypropylene.

(claim 8)

The fibrous cellulose composite resin according to claim 7, wherein the proportion of the maleic anhydride-modified polypropylene is 0.1 to 1000 parts by mass with respect to 100 parts by mass of the microfibrillar cellulose.

(claim 9)

The fibrous cellulose composite resin according to claim 1, which comprises at least one member selected from the group consisting of a polybasic acid, a derivative of a polybasic acid, and a derivative of a salt of a polybasic acid.

(claim 10)

The fibrous cellulose composite resin according to claim 9, wherein the microfibrillar cellulose is modified with any one of the polybasic acid, the derivative of the polybasic acid, and the derivative of the salt of the polybasic acid.

(claim 11)

The fibrous cellulose composite resin according to claim 9, wherein the polybasic acid is phthalic acid, and the polybasic acid salt is a phthalate salt.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a fibrous cellulose composite resin which is excellent in strength, particularly flexural modulus, and which does not have a problem of coloration, and a method for producing the same can be obtained.

Detailed Description

The following describes a specific embodiment. The present embodiment is an example of the present invention. The scope of the present invention is not limited to the scope of the present embodiment.

The fibrous cellulose composite resin of the present embodiment contains microfibrillar cellulose having an average fiber width of 0.1 μm or more, a resin, and a polyacid salt. In addition, in order to obtain the fibrous cellulose composite resin, the raw material fiber is opened to prepare the microfibrillar cellulose with the average fiber width of more than 0.1 μm, and the microfibrillar cellulose, the resin and the polyacid salt are mixed to obtain the fibrous cellulose composite resin containing the polyacid salt.

Further, the fibrous cellulose composite resin of the present embodiment preferably contains maleic anhydride-modified polypropylene (MAPP). More preferably, the additive contains at least one or more selected from the group consisting of a polybasic acid, a derivative of a polybasic acid, and a derivative of a salt of a polybasic acid. Particularly preferably, the composition contains at least one or more of the 2 nd additive selected from the group consisting of ethylene glycol, a derivative of ethylene glycol, an ethylene glycol polymer, and a derivative of an ethylene glycol polymer. In addition, in the case of obtaining a fibrous cellulose composite resin, for example, a raw material fiber is opened to prepare a microfibrillar cellulose having an average fiber width of 0.1 μm or more, and the microfibrillar cellulose, a resin, maleic anhydride-modified polypropylene, the additive, and the like are kneaded to obtain a fibrous cellulose composite resin containing maleic anhydride-modified polypropylene. The following description will be made in order.

(raw material fiber)

The microfibril cellulose (MFC) can be obtained by micronization (opening) treatment of raw material fibers (pulp fibers). The raw material fiber may be selected from 1 or 2 or more types selected from plant-derived fiber, animal-derived fiber, and microorganism-derived fiber. Among them, pulp fiber as plant fiber is preferably used. When the raw material fiber is pulp fiber, the cost is low, and the problem of heat recovery can be avoided.

The plant-derived fibers may be selected from wood pulp made from broad-leaved trees, coniferous trees, and the like; non-wood pulp using straw/bagasse and the like as raw materials; 1 or 2 or more kinds of waste paper pulp (DIP) and the like are selected from recycled waste paper, broke and the like as raw materials and used.

The wood pulp may be selected from 1 or 2 or more of chemical pulps such as hardwood kraft pulp (LKP) and softwood kraft pulp (NKP), mechanical pulp (TMP) and waste paper pulp (DIP). These pulps are pulps used in papermaking applications, and by using these pulps, existing equipment can be effectively utilized.

The hardwood sulphate pulp (LKP) can be bleached hardwood sulphate pulp, unbleached hardwood sulphate pulp or semi-bleached hardwood sulphate pulp. Similarly, softwood kraft pulp (NKP) may be softwood bleached kraft pulp, may be softwood unbleached kraft pulp, or may be softwood semi-bleached kraft pulp.

In addition, the used paper pulp (DIP) may be magazine used paper pulp (MDIP), newspaper used paper pulp (NDIP), corrugated cardboard used paper pulp (WP), or other used paper pulp.

Further, as the mechanical pulp, for example, 1 or 2 or more selected from among millstone mill pulp (SGP), pressure mill Pulp (PGW), wood chip mill pulp (RGP), chemical mill pulp (CGP), thermomechanical pulp (TGP), mill pulp (GP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), disc mill pulp (RMP), bleached thermomechanical pulp (BTMP), and the like can be used.

(pretreatment step)

The raw fibers are preferably pretreated chemically. By performing the pretreatment by a chemical method before the micronization (opening) treatment, the number of micronization treatments can be greatly reduced, and the energy of micronization treatment can be greatly reduced.

Examples of the pretreatment by a chemical method include hydrolysis of polysaccharide by an acid (acid treatment), hydrolysis of polysaccharide by an enzyme (enzyme treatment), swelling of polysaccharide by an alkali (alkali treatment), oxidation of polysaccharide by an oxidizing agent (oxidation treatment), reduction of polysaccharide by a reducing agent (reduction treatment), and the like.

By performing the alkali treatment before the micronization treatment, the following effects are obtained: the hydroxyl group part of hemicellulose or cellulose in the pulp is dissociated to anionize molecules, thereby weakening the hydrogen bonds between molecules and promoting the dispersion of pulp fibers in the refining treatment.

Examples of the base include organic bases such as sodium hydroxide, lithium hydroxide, potassium hydroxide, aqueous ammonia solution, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and benzyltrimethylammonium hydroxide, and sodium hydroxide is preferably used from the viewpoint of production cost.

When the enzyme treatment, the acid treatment, and the oxidation treatment are performed before the pulverization treatment, the water retention of the microfibril cellulose can be reduced, the crystallinity can be improved, and the homogeneity can be improved. In this regard, it is considered that the lower the water retention degree of the microfibril cellulose, the higher the dispersibility in the resin is, and the higher the homogeneity of the microfibril cellulose, the less the defect which is a factor of destruction of the resin composition is, and as a result, it is considered that a composite resin having a high strength capable of maintaining the ductility of the resin can be obtained. Further, the amorphous regions of hemicellulose or cellulose contained in the pulp are decomposed by the enzyme treatment, the acid treatment, and the oxidation treatment, and as a result, the energy for the refining treatment can be reduced, and the homogeneity and dispersibility of the fibers can be improved. Further, when the proportion of the cellulose crystal domain, which is considered to be rigid and low in water retention, in the entire fiber is increased with the molecular chains aligned, the dispersibility is improved, and a composite resin having high mechanical strength while maintaining ductility is obtained despite the fact that the aspect ratio is apparently decreased.

Among the above various treatments, the enzyme treatment is preferably performed, and 1 or 2 or more treatments selected from the group consisting of acid treatment, alkali treatment and oxidation treatment are more preferably performed. The alkali treatment will be described in detail below.

As a method of alkali treatment, for example, there is a method of immersing the raw material fiber in an alkali solution.

The alkali compound contained in the alkali solution may be an inorganic alkali compound or an organic alkali compound.

Examples of the inorganic basic compound include hydroxides of alkali metals or alkaline earth metals, carbonates of alkali metals or alkaline earth metals, and phosphorous oxyacid salts of alkali metals or alkaline earth metals.

Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the alkaline earth metal hydroxide include calcium hydroxide and the like. Examples of the carbonate of an alkali metal include lithium carbonate, lithium hydrogencarbonate, potassium carbonate, potassium hydrogencarbonate, sodium carbonate, sodium hydrogencarbonate, and the like. Examples of the carbonate of an alkaline earth metal include calcium carbonate and the like. Examples of the alkali metal oxophosphate include lithium phosphate, potassium phosphate, trisodium phosphate, and disodium hydrogen phosphate. Examples of the alkaline earth metal phosphate include calcium phosphate and calcium hydrogen phosphate.

Examples of the organic basic compound include ammonia, aliphatic amines, aromatic amines, aliphatic ammonium, aromatic ammonium, heterocyclic compounds, and hydroxides, carbonates, phosphates thereof. Specifically, for example, ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentane, diaminohexane, cyclohexylamine, aniline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, pyridine, N-dimethyl-4-aminopyridine, ammonium carbonate, ammonium bicarbonate, diammonium hydrogen phosphate, and the like can be exemplified.

The solvent of the alkaline solution may be any of water and an organic solvent, and is preferably a polar solvent (a polar organic solvent such as water or alcohol), and more preferably an aqueous solvent containing at least water.

The pH of the alkali solution at 25 ℃ is preferably 9 or more, more preferably 10 or more, and particularly preferably 11 to 14. When the pH is 9 or more, the yield of microfibrillar cellulose (MFC) is increased. However, when the pH is more than 14, the handling property of the alkali solution is lowered.

(micronization (splitting) Process)

The micronization treatment can be carried out by beating the raw material fibers using, for example, a homogenizer such as a beater, a high-pressure homogenizer, or a high-pressure homogenizer, a stone-mortar type friction machine such as a grinder or an attritor, a single-shaft mixer, a multi-shaft mixer, a kneader, or a homogenizer, and is preferably carried out using a homogenizer.

The refiner is a device for beating pulp fibers, and a known refiner can be used. As the refiner, a conical or Double Disc Refiner (DDR) and a Single Disc Refiner (SDR) are preferable in terms of efficiently imparting a shearing force to the pulp fiber and enabling pre-opening. When a refiner is used in the opening treatment step, it is also preferable that separation and washing after the treatment are not necessary.

The microfibril cellulose is a fiber formed from cellulose or a cellulose derivative. Ordinary microfibril cellulose has strong hydration property, and is hydrated in an aqueous medium to stably maintain a dispersion state (state of a dispersion liquid). The single fibers constituting the microfibrillar cellulose may be formed into a fibrous shape by collecting a plurality of filaments in an aqueous medium.

The micronization (opening) treatment is preferably carried out in a range in which the number average fiber diameter (fiber width; average diameter of single fibers) of the microfibril cellulose is 0.1 μm or more, more preferably in a range in which the number average fiber diameter is 0.1 to 15 μm, and particularly preferably in a range in which the number average fiber diameter is 0.1 to 9 μm. By setting the number average fiber diameter (width) to a range of 0.1 μm or more, the dispersibility of the cellulose fibers is improved, and the strength of the fibrous cellulose composite resin is improved.

Specifically, if the average fiber diameter is less than 0.1 μm, the reinforcing effect (particularly, flexural modulus) cannot be sufficiently obtained, unlike cellulose nanofibers. In addition, the miniaturization process takes a long time, and requires a large amount of energy, which increases the manufacturing cost. On the other hand, when the average fiber diameter is larger than 15 μm, the dispersibility of the fibers tends to be poor. If the dispersibility of the fibers is insufficient, the reinforcing effect tends to be poor. When the average fiber diameter is less than 0.1 μm, the viscosity becomes too high when the fibrous cellulose is mixed with the polybasic acid salt and the maleic anhydride-modified polypropylene in the form of an aqueous dispersion, and stirring with a high shear force is required, which is disadvantageous in terms of energy. Further, when stirring is performed with a high shear force, the fibrous cellulose may be broken, deteriorated, or the like.

The average fiber length (length of single fibers) of the microfibrillar cellulose is preferably 0.02 to 3.0mm, more preferably 0.05 to 2.0mm, and particularly preferably 0.1 to 1.5 mm. When the average fiber length is less than 0.02mm, a three-dimensional network of fibers may not be formed, and the reinforcing effect may be significantly reduced. The average fiber length can be arbitrarily adjusted by, for example, selection of raw fibers, pretreatment, and opening treatment.

The fibrillation rate of the microfibril cellulose is preferably 1.0% or more, more preferably 1.5% or more, and particularly preferably 2.0% or more. The fibrillation ratio of the microfibril cellulose is preferably 30.0% or less, more preferably 20.0% or less, and particularly preferably 15.0% or less.

If the fibrillation rate is more than 30.0%, the nanofibers are formed by excessive micronization, and the desired effect may not be obtained. When the fibrillation rate is more than 30%, the viscosity becomes too high when the fibrous cellulose is mixed with the polybasic acid salt and the maleic anhydride-modified propylene in the form of an aqueous dispersion, and it may be difficult to stir the fibrous cellulose uniformly. However, if the agitation is performed with difficulty, the fibrous cellulose may be broken or deteriorated.

On the other hand, if the fibrillation rate is less than 1.0%, hydrogen bonds between fibrils are small, and a strong three-dimensional network is lacking. In this regard, the present inventors have found that, in the course of various experiments, when the fibrillation rate of the microfibril cellulose is set to 1.0% or more, fibrils of the microfibril cellulose form hydrogen bonds with each other, and a stronger three-dimensional network is constructed.

The proportion of the microfibril cellulose of 0.2mm or less in the fiber length is preferably 12% or more, more preferably 16% or more, and particularly preferably 26% or more. When the ratio is less than 12%, a sufficient reinforcing effect may not be obtained.

The proportion of the microfibril cellulose in the fiber length of 0.2mm or less has no upper limit, and may be 0.2mm or less in total.

The aspect ratio of the microfibrillar cellulose is preferably 2 to 5,000, and more preferably 100 to 1,000, in order to maintain ductility of the resin to some extent and improve mechanical strength.

The aspect ratio is a value obtained by dividing the average fiber length by the average fiber width. It is considered that the larger the aspect ratio, the more positions where hooks are generated in the resin, and thus the reinforcing effect is improved; on the other hand, however, the ductility of the resin decreases to such an extent that the resin is caught by a large amount. When an inorganic filler is kneaded with a resin, the following findings are obtained: the larger the aspect ratio of the filler, the higher the flexural strength, but the significantly lower the elongation.

The crystallinity of the microfibril cellulose is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more. When the crystallinity is less than 50%, the strength of the fiber itself is lowered although the compatibility with the resin is improved, and thus the reinforcing effect of the resin composition tends to be poor.

On the other hand, the crystallinity of the microfibril cellulose is preferably 90% or less, more preferably 88% or less, and particularly preferably 86% or less. When the crystallinity is more than 90%, the proportion of strong hydrogen bonds in the molecule increases, and the fiber itself becomes rigid, but the compatibility with the resin decreases, and the reinforcing effect of the resin composition tends to be poor.

The crystallinity can be arbitrarily adjusted by, for example, selection of raw material fibers, pretreatment, and refining treatment.

The pulp viscosity of the microfibrillar cellulose is preferably 2cps or more, more preferably 4cps or more. If the pulp viscosity is less than 2cps, the aggregation of the microfibril cellulose cannot be sufficiently suppressed when the microfibril cellulose and the resin are kneaded, and the reinforcing effect of the resin composition tends to be poor.

The beating degree of the microfibril cellulose is preferably 500cc or less, more preferably 300cc or less, and particularly preferably 100cc or less. If the freeness is more than 500cc, the width of the microfibrillar cellulose is more than 15 μm, and the reinforcing effect is insufficient.

(kneading)

The microfibril cellulose obtained by the micronization treatment can be dispersed in an aqueous medium to prepare a dispersion. The aqueous medium is particularly preferably water entirely, but an aqueous medium in which a part of the aqueous medium is another liquid compatible with water may be preferably used. As the other liquid, lower alcohols having 3 or less carbon atoms and the like can be used.

The solid content concentration of the dispersion is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and particularly preferably 2.0% by mass or more. The solid content concentration of the dispersion is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

The microfibril cellulose may be subjected to dehydration treatment and drying treatment before being kneaded with a resin or the like. That is, the dehydration/drying treatment and the kneading treatment of the microfibril cellulose may be performed not together, or the microfibril cellulose may be dried while kneading. The dehydration treatment and the drying treatment may be performed together or separately.

In the dehydration treatment, for example, 1 or 2 or more kinds of them can be selected from a belt press, a screw press, a filter press, a twin-roll press, a nip former, a valveless filter, a centrisc filter, a membrane treatment, a centrifuge, and the like.

In the drying treatment, for example, 1 or 2 or more kinds of drying selected from rotary kiln drying, disc drying, pneumatic drying, medium flow drying, spray drying, drum drying, screw conveyor drying, impeller drying, uniaxial kneading drying, multiaxial kneading drying, vacuum drying, stirring drying, and the like can be used.

The dehydration/drying treatment process may be followed by a pulverization treatment process. For the pulverization treatment, for example, 1 or 2 or more kinds of them can be selected from a bead mill, a kneader, a disperser, a kneader, a chopper, a hammer mill, and the like.

The dehydrated/dried microfibril cellulose may be in the form of powder, granules, flakes, etc. Among them, powder is preferable.

When the microfibril cellulose is made into a powder, the average particle size of the microfibril cellulose is preferably 1 to 10,000 μm, more preferably 10 to 5,000 μm, and particularly preferably 100 to 1,000 μm. If the average particle diameter is larger than 10,000. mu.m, the particles may not be introduced into the kneading apparatus because of their large particle diameter. On the other hand, if the average particle size is less than 1 μm, the pulverization treatment requires energy, and is therefore uneconomical.

When the microfibril cellulose is made into a powder, the bulk density of the microfibril cellulose is preferably 0.01 to 1.5, more preferably 0.04 to 1, and particularly preferably 0.1 to 0.5. A bulk specific gravity of more than 1.5 means that the specific gravity of cellulose is more than 1.5, and thus is physically difficult to achieve. On the other hand, it is disadvantageous from the viewpoint of transportation cost to set the bulk specific gravity to less than 0.01.

The moisture content (water content) of the dehydrated/dried microfibril cellulose is preferably 0.1% or more, more preferably 1.0% or more, and particularly preferably 10.0% or more. When the moisture content of the microfibril cellulose kneaded with the polybasic acid salt is 0.1% or more, the cellulose fiber is not modified with the polybasic acid salt, and the obtained composite resin contains the polybasic acid salt. When an additive such as a polybasic acid or a polybasic acid salt is added, if the moisture content of the microfibrillated cellulose is 0.1% or more, the cellulose fiber is not modified with the additive, and the obtained composite resin contains the additive.

The dewatered/dried microfibril cellulose may contain a resin. When the resin is contained, hydrogen bonds between the dehydrated and dried microfibril cellulose are suppressed, and dispersibility in the resin during kneading can be improved.

Examples of the form of the resin contained in the dehydrated and dried microfibril cellulose include powder, granule, and sheet. Among them, powder (powder resin) is preferable.

When the resin powder is made into a powder, the average particle diameter of the resin powder contained in the dehydrated/dried microfibril cellulose is preferably 1 to 10,000 μm, more preferably 10 to 5,000 μm, and particularly preferably 100 to 1,000 μm. If the average particle diameter is larger than 10,000. mu.m, the particle diameter may become too large to enter the kneading apparatus. On the other hand, if the average particle diameter is less than 1 μm, hydrogen bonding between microfibril celluloses may not be inhibited due to their fineness. The resin such as a powdered resin used herein and the resin kneaded with the microfibrillar cellulose (resin as a main raw material) may be the same resin or different resins, and the same resin is preferable.

The resin powder having an average particle diameter of 1 to 10,000 μm is preferably mixed in an aqueous dispersion state before dehydration/drying. By mixing in an aqueous dispersion state, the resin powder can be uniformly dispersed among the microfibrils, and the microfibrils can be uniformly dispersed in the kneaded composite resin, thereby further improving the strength properties.

The microfibrillar cellulose obtained as described above is kneaded with a resin to prepare a kneaded product. In this kneading, a polybasic acid salt, maleic anhydride-modified polypropylene, or the like is further added. As described above, the moisture content of the microfibril cellulose is important when kneading.

As the resin, any of thermoplastic resins and thermosetting resins can be used.

The thermoplastic resin may be selected from 1 or 2 or more of polyolefins such as polypropylene (PP) and Polyethylene (PE), polyester resins such as aliphatic polyester resins and aromatic polyester resins, polyacrylic resins such as polystyrene, methacrylate and acrylate, polyamide resins, polycarbonate resins, polyacetal resins, and the like.

Among them, at least either one of polyolefin and polyester resins is preferably used. As the polyolefin, polypropylene is preferably used.

The polypropylene may be used in the form of 1 or 2 or more kinds selected from homopolymers, random polymers and block polymers. In addition, as the polyester resin, for example, polylactic acid, polycaprolactone and the like can be exemplified as the aliphatic polyester resin, and for example, polyethylene terephthalate and the like can be exemplified as the aromatic polyester resin, and a biodegradable polyester resin (also simply referred to as "biodegradable resin") is preferably used.

The biodegradable resin may be selected from 1 or 2 or more species of hydroxycarboxylic acid aliphatic polyesters, caprolactone aliphatic polyesters, dibasic acid polyesters, and the like.

The hydroxycarboxylic acid-based aliphatic polyester may be used in the form of 1 or 2 or more species selected from homopolymers of hydroxycarboxylic acids such as lactic acid, malic acid, gluconic acid and 3-hydroxybutyric acid, and copolymers using at least one of these hydroxycarboxylic acids. Among them, polylactic acid, a copolymer of lactic acid and the above-mentioned hydroxycarboxylic acid other than lactic acid, polycaprolactone, a copolymer of caprolactone and at least one of the above-mentioned hydroxycarboxylic acids are preferably used, and polylactic acid is particularly preferably used.

As the lactic acid, for example, L-lactic acid, D-lactic acid, and the like can be used, and these lactic acids can be used alone, or 2 or more kinds can be selected and used.

The caprolactone-based aliphatic polyester may be used by selecting 1 or 2 or more species from, for example, a homopolymer of polycaprolactone, a copolymer of polycaprolactone and the above hydroxycarboxylic acid, and the like.

The dibasic acid polyester may be selected from 1 or 2 or more species selected from polybutylene succinate, polyethylene succinate, polybutylene adipate, and the like.

The biodegradable resin may be used alone in 1 kind, or two or more kinds may be used in combination.

Examples of the thermosetting resin include phenol resins, urea resins, melamine resins, furan resins, unsaturated polyesters, diallyl phthalate resins, vinyl ester resins, epoxy resins, urethane resins, silicone resins, and thermosetting polyimide resins. These resins may be used alone or in combination of two or more.

The resin may contain an inorganic filler in a proportion that preferably does not hinder heat recovery.

Examples of the inorganic filler include simple substances of metal elements in groups I to VIII of the periodic table, such as Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, and silicon, oxides, hydroxides, carbonates, sulfates, silicates, and sulfites, and various clay minerals made of these compounds.

Specific examples thereof include barium sulfate, calcium sulfate, magnesium sulfate, sodium sulfate, calcium sulfite, zinc oxide, silicon dioxide, ground calcium carbonate, light calcium carbonate, aluminum borate, aluminum oxide, iron oxide, calcium titanate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, clay wollastonite, glass beads, glass powder, silica sand, silica, quartz powder, diatomaceous earth, white carbon, and glass fiber. These inorganic fillers may contain a plurality of kinds. Further, the inorganic filler may be an inorganic filler contained in the waste paper pulp.

The proportion of the microfibril cellulose to the resin is preferably 0.1 to 100 parts by mass, more preferably 1 to 80 parts by mass, and particularly preferably 5 to 60 parts by mass, based on 100 parts by mass of the resin. Wherein, when the mixing proportion of the microfibril cellulose is 0.1-100 parts by mass, the strength, particularly the bending strength and the bending modulus of the composite resin can be remarkably improved.

The content ratio of the microfibrillated cellulose and the resin contained in the finally obtained composite resin is generally the same as the above-mentioned mixing ratio of the microfibrillated cellulose and the resin.

(salts of polybasic acids and the like)

When the microfibril cellulose and the resin are mixed, at least one additive selected from the group consisting of polybasic acids, derivatives of polybasic acids, and derivatives of polybasic acid salts may be added in addition to the polybasic acid salts and the maleic anhydride-modified polypropylene.

The additive such as the polybasic acid may be used by selecting 1 or 2 or more from oxalic acid, phthalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, tartaric acid, glutamic acid, sebacic acid, hexafluosilicic acid, maleic acid, itaconic acid, citraconic acid, citric acid, and the like. Among them, at least one or more of phthalic acid, phthalic acid salts, and derivatives thereof (phthalic acids) are preferable.

Examples of the polybasic acid salts include oxalate, malonate, succinate, glutarate, adipate, tartrate, glutamate, sebacate, hexafluorosilicate, maleate, itaconate, citraconate, citrate, phthalate, and phthalate derivatives. When the polybasic acid salt is used, the coloring of the obtained resin composition can be suppressed and the foaming at high temperature can be suppressed, as compared with the case of using the polybasic acid. In addition, it is known that in the polybasic acid salts, since the hydrogen ions of the carboxyl groups are smaller than those of the polybasic acid, the acid decomposition of the cellulose fiber can be suppressed, and the coloring can be suppressed. Further, it is known that polybasic acids are more easily volatilized at high temperatures than polybasic acid salts, and are easily foamed.

Among them, as the polybasic acid salt, at least either one of a phthalate salt, a phthalate salt derivative, and the like is preferably used. By using a phthalate or a derivative thereof, the flexural modulus of the resulting resin composition can be improved.

In this case, the phthalate salt is preferably at least one or more selected from the group consisting of potassium hydrogen phthalate, sodium phthalate and ammonium phthalate.

Examples of the phthalic acid derivative include phthalic acid, potassium hydrogen phthalate, sodium phthalate, ammonium phthalate, dimethyl phthalate, diethyl phthalate, diallyl phthalate, diisobutyl phthalate, di-n-hexyl phthalate, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, and di (triisodecyl) phthalate. Phthalic acid is preferably used, and phthalate salts are more preferably used.

When a polybasic acid salt such as a phthalate is used, the coloring of the obtained resin composition can be suppressed and the foaming at high temperature can be suppressed as compared with the case of using a polybasic acid. In addition, it is known that in the polybasic acid salts, since the hydrogen ions of the carboxyl groups are smaller than those of the polybasic acid, the acid decomposition of the cellulose fiber can be suppressed, and the coloring can be suppressed. Further, it is known that polybasic acids are more easily volatilized at high temperatures than polybasic acid salts, and are easily foamed. Further, when a phthalate salt or a phthalate salt derivative, which is a polybasic acid salt, is used, the flexural modulus of the resulting resin composition is improved.

The polybasic acid anhydrides may be selected from 1 or 2 or more species selected from maleic anhydride, phthalic anhydride, itaconic anhydride, citraconic anhydride, citric anhydride, and the like. Among them, maleic anhydride is preferably used, and phthalic anhydride is more preferably used.

Examples of the phthalic anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hydroxyphthalic anhydride, hexahydrophthalic anhydride, 4-ethynylphthalic anhydride, and 4-phenylethynylphthalic anhydride. Among them, phthalic anhydride is preferably suitably used.

The main object of this embodiment is not to modify microfibrillar cellulose with a polyacid salt (replacing a part of the hydroxyl groups with specific functional groups). In this embodiment, the use of a polybasic acid salt as a compatibilizer improves (improves compatibility) the strength and the like of the obtained composite resin. In this regard, if the cellulose fiber is not modified, the quality of the obtained composite resin is stable.

However, in this embodiment, the microfibrillar cellulose may be partially modified with the polybasic acid salt. When cellulose fibers are modified with a polyacid salt, a part of the hydroxyl groups are substituted with a specific functional group, and the compatibility between microfibrillar cellulose and a resin is improved.

In addition, when cellulose fibers are modified with a part of additives such as polybasic acids, instead of simply containing the additives, a part of the hydroxyl groups of the cellulose fibers are substituted with specific functional groups, and the compatibility between the microfibrillar cellulose and the resin is further improved. However, even when an additive such as a polybasic acid is simply contained, the additive functions as a compatibilizer, and thus the compatibility is improved. As a result, the strength, particularly the bending strength, of the obtained fibrous cellulose composite resin is improved.

When an additive such as a polybasic acid functions as a compatibilizer, the progress of the modification of the cellulose fiber is not problematic, and the quality of the resulting composite resin is stable. However, attention must be paid to the moisture content of the microfibril cellulose during kneading (in this regard, as described above), and care must be taken not to excessively modify the cellulose fibers.

The modification of the microfibril cellulose based on the polybasic acid salt is preferably performed in such a manner that a part of the hydroxyl groups of the cellulose constituting the fiber is substituted with a functional group represented by the following structural formula.

[ solution 1]

R in the structural formula is any one of the following groups: a linear, branched or cyclic saturated hydrocarbon group or a derivative thereof; a linear, branched or cyclic unsaturated hydrocarbon group or a derivative thereof; an aromatic group or a derivative thereof. Further, α is a cation having a valence of 1 or more formed of an organic or inorganic substance.

In addition, the microfibrillar cellulose is preferably modified by the additive in such a manner that a part of the hydroxyl groups of the cellulose constituting the fiber is substituted with a functional group represented by the following structural formula (1) or (2).

[ solution 2]

R in the structural formula is any one of the following groups: a linear, branched or cyclic saturated hydrocarbon group or a derivative thereof; a linear, branched or cyclic unsaturated hydrocarbon group or a derivative thereof; an aromatic group or a derivative thereof.

In the kneading treatment, for example, 1 or 2 or more types of kneading machines can be selected from a single-shaft or twin-shaft or more multi-shaft kneading machine, a mixing roll, a kneader, a roll mill, a Banbury mixer, a screw press, a disperser, and the like. Among these, a twin-shaft or higher multi-shaft kneader is preferably used. More than two twin-shaft or more than 2 twin-shaft kneading machines may be used in series or in parallel.

The temperature of the kneading treatment is not less than the glass transition point of the resin, and varies depending on the type of the resin, and is preferably 80 to 280 ℃, more preferably 90 to 260 ℃, and particularly preferably 100 to 240 ℃.

The compounding ratio of the additive such as a polybasic acid salt or a polybasic acid is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass, relative to 100 parts by mass of the microfibril cellulose. When the compounding ratio of the polybasic acid salts is less than 0.1 part by mass, a sufficient reinforcing effect cannot be obtained. On the other hand, when the compounding ratio of the polybasic acid salts is more than 1,000 parts by mass, the reinforcing effect is not further improved.

(additive No. 2: ethylene glycol, etc.)

In the mixing of the microfibrillar cellulose and the resin, at least one or more additives (additive 2) selected from the group consisting of ethylene glycol, a derivative of ethylene glycol, an ethylene glycol polymer, and a derivative of an ethylene glycol polymer may be added in addition to additives such as a polybasic acid salt and a polybasic acid. By adding this additive No. 2, the dispersibility of the microfibrillar cellulose is significantly improved. In this regard, the present inventors have found that when the cellulose fibers are cellulose nanofibers, the dispersibility of the cellulose fibers is not improved. In this connection, it is presumed that the 2 nd additive is incorporated into the microfibril cellulose to inhibit aggregation in the resin and improve dispersibility. However, since the specific surface area of the cellulose nanofibers is significantly higher than that of the microfibrillar cellulose, it is assumed that the additive 2 is not introduced between the cellulose nanofibers even if it is excessively added.

The addition amount of the 2 nd additive is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass, based on 100 parts by mass of the microfibril cellulose. When the additive amount of the 2 nd additive is less than 0.1 part by mass, it does not contribute to the improvement of the dispersibility of the microfibrillar cellulose. On the other hand, when the amount of the 2 nd additive is more than 1,000 parts by mass, the additive is excessively added, which may adversely decrease the strength of the resin.

The molecular weight of the 2 nd additive is preferably 1 to 20,000, more preferably 10 to 4,000, and particularly preferably 100 to 2,000. Physically, the molecular weight of the 2 nd additive cannot be below 1. On the other hand, when the molecular weight of the 2 nd additive is higher than 20,000, the volume becomes large, and thus the microfibril cellulose cannot enter between each other.

(maleic anhydride-modified Polypropylene)

Maleic anhydride modified polypropylene (MAPP) is also preferably added at the time of mixing of the microfibrillar cellulose and the resin. When the maleic anhydride-modified polypropylene is added, the strength, particularly the flexural strength of the resin composition obtained is improved.

The amount of the maleic anhydride-modified polypropylene to be added is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass, based on 100 parts by mass of the microfibrillar cellulose. When the amount of the maleic anhydride-modified polypropylene added is less than 0.1 part by mass, the strength is not sufficiently improved. On the other hand, when the amount of the maleic anhydride-modified polypropylene added is more than 1,000 parts by mass, the addition is excessive, and the strength tends to be lowered.

The weight average molecular weight of the maleic anhydride modified polypropylene is 1,000-100,000, preferably 3,000-50,000.

The acid value of the maleic anhydride-modified polypropylene is preferably 0.5mgKOH/g or more and 100mgKOH/g or less, more preferably 1mgKOH/g or more and 50mgKOH/g or less.

(other compositions)

The microfibril cellulose may contain 1 or 2 or more of various types of microfine fibers called cellulose nanofibers, microfibrillar cellulose, microfibrillar microfine fibers, microfibrillated cellulose, and the like, or may contain these microfine fibers unintentionally. The microfibril cellulose may contain fibers obtained by further refining these microfine fibers, or may contain these fibers unintentionally. However, the proportion of microfibril cellulose in the entire raw material fibers needs to be 10 mass% or more, preferably 30 mass% or more, and more preferably 60 mass% or more.

In addition to the above, the microfibril cellulose may contain fibers derived from plant materials obtained from various plants such as hibiscus hemp, jute, manila hemp, sisal hemp, wild goose skin, kohlrabi, broussonetia papyrifera, banana, pineapple, coconut palm, corn, sugarcane, bagasse, coconut, papyrus, reed, esparto grass, sabai grass, wheat, rice, bamboo, various conifers (cedar, cypress, etc.), broad leaf trees, cotton, and the like, or may contain these fibers unintentionally.

The fibrous cellulose composite resin may be used in a range not interfering with the effects of the present invention, in which 1 or 2 or more kinds of additives selected from, for example, antistatic agents, flame retardants, antibacterial agents, coloring agents, radical scavengers, foaming agents, and the like, in addition to the microfibrillar cellulose, the resin, the polyacid salts, and the above additives, are used as raw materials.

These raw materials may be mixed in a dispersion of the microfibril cellulose, may be kneaded together at the time of kneading the microfibril cellulose and the resin, may be kneaded in a kneaded mixture thereof, or may be kneaded by other methods. Among these, in terms of production efficiency, it is preferable to perform kneading together when the microfibril cellulose and the resin are kneaded.

(Molding treatment)

The microfibrillar cellulose and the resin (kneaded product) are preferably kneaded again as necessary and then molded into a desired shape. The kneaded product, in which microfibril cellulose is dispersed, is excellent in moldability.

The size, thickness, shape and the like of the molding are not particularly limited, and the molding may be made into, for example, a sheet, a granule, a powder, a fiber or the like.

The temperature at the time of molding treatment is not less than the glass transition point of the resin, and varies depending on the type of the resin, and is preferably 80 to 280 ℃, more preferably 90 to 260 ℃, and particularly preferably 100 to 240 ℃.

The molding treatment apparatus may be, for example, 1 or 2 or more types selected from an injection molding machine, a blow molding machine, a compression molding machine, an extrusion molding machine, a vacuum molding machine, an air pressure molding machine, and the like.

The molding treatment can be performed by a known molding method, and for example, can be performed by die molding, injection molding, extrusion molding, blow molding, foam molding, or the like. Alternatively, the kneaded product may be spun into a fiber form, and mixed with the plant material or the like to form a mat or a plate. The mixing of the fibers can be performed by, for example, a method of simultaneously stacking the fibers by air-laying.

The molding treatment may be performed subsequently to the kneading treatment, or the kneaded product may be cooled and then broken into pieces by a crusher or the like, and the pieces may be fed into a molding machine such as an extrusion molding machine or an injection molding machine.

(definition of terms, measurement method, etc.)

Unless otherwise stated, terms in the specification are as follows.

(average fiber diameter)

100ml of an aqueous dispersion of microfibrillated cellulose having a solid content of 0.01 to 0.1 mass% was filtered through a teflon (registered trademark) membrane filter, and 1 solvent substitution was performed with 100ml of ethanol and 3 solvent substitutions were performed with 20ml of tert-butanol. Subsequently, the coating was freeze-dried and osmium-coated to prepare a sample. The sample was observed at any of 5000 times, 10000 times, or 30000 times according to the width of the constituting fiber by an electron microscope SEM image. Specifically, two diagonal lines are drawn on the observation image, and three straight lines passing through the intersections of the diagonal lines are arbitrarily drawn. Further, the width of total 100 fibers interlaced with the three straight lines was measured visually. And, the median diameter of the measured values was taken as the average fiber diameter.

(average fiber length)

The length of each fiber was measured by visual observation in the same manner as in the case of the average fiber diameter. The median length of the measurements was taken as the average fiber length.

(fiber analysis)

The proportion of a fiber length of 0.2mm or less and the fibrillation ratio were measured by a fiber analyzer "FS 5" manufactured by Valmet.

(aspect ratio)

The aspect ratio is a value obtained by dividing the average fiber length by the average fiber width (diameter).

(degree of crystallinity)

The crystallinity is a value measured by X-ray diffraction method according to "X-ray diffraction analysis general rules" of JIS-K0131 (1996). It should be noted that the microfibril cellulose has an amorphous portion and a crystalline portion, and the crystallinity means a proportion of the crystalline portion in the entirety of the microfibril cellulose.

(pulp viscosity)

Measured according to JIS-P8215 (1998). Note that, the higher the pulp viscosity, the higher the degree of polymerization of the microfibrillar cellulose.

(degree of beating)

The freeness is in accordance with JIS P8121-2: 2012 measured value.

(Water content (moisture content))

The moisture content of the fibers was a value calculated as follows: the sample was held at 105 ℃ for 6 hours or more using a constant temperature dryer, and the mass at the time when the mass fluctuation was no longer observed was calculated as the mass after drying by the following equation.

Fiber moisture content (%) [ (mass before drying-mass after drying) ÷ mass before drying ] × 100

Examples

Next, examples of the present invention will be explained.

To 365g of an aqueous dispersion of microfibrillar cellulose having a solid content of 2.75 wt%, 7g of sodium phthalate and 83g of polypropylene powder were added, and the mixture was dried by heating at 105 ℃ to obtain a fine cellulose fiber mixture. The microfibrous cellulose mixture has a moisture content of less than 10%.

Subsequently, the obtained fine cellulose fiber mixture was kneaded at 180 ℃ and 200rpm by a twin-screw kneader to obtain a microfibrillar cellulose composite resin. The microfibril-cellulose composite resin was cut into a cylindrical shape having a diameter of 2mm and a length of 2mm by a pelletizer, and injection-molded at 180 ℃ into a rectangular parallelepiped test piece (length 59mm, width 9.6mm, thickness 3.8 mm). The test was carried out a plurality of times while changing the kind, mixing ratio, and the like of each mixed material. The details are shown in table 1.

The flexural modulus and coloring of the test piece were examined, and the results are shown in table 1. The flexural modulus and the coloring were evaluated as follows.

(bending test)

According to JIS K7171: 2008, measurement is performed. The table shows the following criteria.

O: when the flexural modulus of the resin itself is 1 and the flexural modulus (magnification) of the composite resin is 1.4 times or more

X: when the flexural modulus of the resin itself is 1 and the flexural modulus (magnification) of the composite resin is less than 1.4 times (coloring)

O: the condition from white to light brown is regarded as

X: the condition of dark brown to black is regarded as

Next, other embodiments of the present invention will be explained.

1g of maleic anhydride-modified polypropylene, 7g of phthalic acid, 3g of polyethylene glycol (400), and 79g of polypropylene powder were added to 365g of an aqueous dispersion of microfibrillar cellulose having a solid content of 2.75% by weight, and the mixture was heated and dried at 105 ℃ to obtain a mixture of fibrous cellulose and resin. The water content of the mixture is less than 10%.

Subsequently, the mixture was kneaded at 180 ℃ and 200rpm by a twin-screw kneader to obtain a fibrous cellulose composite resin. The composite resin was cut into a cylindrical shape having a diameter of 2mm and a length of 2mm by a pelletizer, and injection-molded at 180 ℃ into a rectangular parallelepiped test piece (length 59mm, width 9.6mm, thickness 3.8 mm). The test was carried out a plurality of times while changing the kind, mixing ratio, and the like of each mixed material. The details are shown in table 2.

The obtained test pieces were subjected to bending test evaluation as shown in table 2. The bending test was evaluated as follows.

According to JIS K7171: 2008, the measurement is shown by the following criteria.

O: when the flexural modulus of the resin itself is 1 and the flexural modulus (magnification) of the composite resin is 1.5 times or more

X: when the flexural modulus of the resin itself is 1 and the flexural modulus (magnification) of the composite resin is less than 1.5 times

Industrial applicability

The present invention can be used as a fibrous cellulose composite resin and a method for producing the same.