JP6819006B2 - Method for manufacturing cellulose resin composite - Google Patents

Description

The present invention relates to a method for producing a cellulose resin composite.

Cellulose has a specific gravity of 1.5 and has high strength. Pulp used for paper, filters, etc. has established mass productivity and can be supplied in large quantities at low cost. In addition, cellulose is derived from natural products, and unlike underground resources such as petroleum and coal, it can be regenerated in one to several decades. Therefore, diversifying the use of cellulose is an important theme for us human beings.

One of the uses of cellulose is a cellulose resin composite in which a general-purpose resin typified by a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is composited with cellulose, and the cellulose resin composite is It is used as a molded product such as a press molded product, an extrusion molded product, and an injection molded product. Cellulose has a high elastic modulus. For example, when cellulose and polyolefin are combined, the elastic modulus of polyolefin can be increased in the same manner as when glass or talc and cellulose are combined. However, the highly hydrophilic cellulose surface and the highly hydrophobic polyolefin have low affinity, and the cellulose cannot take a good dispersed state in the polyolefin and aggregates, resulting in a high-strength cellulose resin composite. It was difficult to get a body.

There are two ways to improve this. The first method is a method of surface-modifying cellulose to increase its affinity with a resin, but it is not a practical method because it is costly because the cellulose is chemically modified in advance to modify the surface. The second method is to add a material that enhances the affinity between cellulose and the resin to the composite. However, as a material for enhancing affinity, an acid-modified polyolefin obtained by adding maleic anhydride, itaconic acid, or the like to polyolefin has been proposed (see, for example, Patent Documents 1 and 2), and although the strength characteristics are improved, It cannot be said that the surface of the cellulose in the composite is sufficiently wet with the resin, which leaves a problem. As a typical technique for solving this problem, there is a technique of improving the elastic modulus of a molded product by heat-treating it at 150 ° C. to 160 ° C. (see, for example, Patent Document 3). However, heat treatment of a molded product increases the number of processing steps and rebounds to the manufacturing cost. Therefore, a technique for exhibiting a high elastic modulus without such heat treatment has been required.

Further, in the second method, a method of using an acid-modified polyolefin and a water-soluble resin in combination as a material for enhancing the affinity has been proposed (see, for example, Patent Document 4). In Patent Document 4, cellulose, a thermoplastic resin, an acid-modified polyolefin, and a water-soluble resin are melt-kneaded. A step of mixing and drying cellulose and a water-soluble resin to obtain a mixture, and a mixture obtained. On the other hand, it is described that a cellulose resin composite having improved cellulose dispersibility can be obtained in a production method including a step of adding a thermoplastic resin and an acid-modified polyolefin and melt-kneading. However, in the method of Patent Document 4, two steps are required to obtain the cellulose resin composite, and the mixture of cellulose and the water-soluble resin must be dried once, so that the number of steps and the required energy are required. There is a problem that the number increases.

Special Fair 7-5751 Japanese Patent No. 5433949 Japanese Patent No. 4491138 Japanese Unexamined Patent Publication No. 2012-236906

An object of the present invention is that in a method for producing a cellulose resin composite capable of obtaining a cellulose resin composite having good dispersibility of cellulose and capable of exhibiting a high elastic modulus, heat treatment of the molded product is not required, and the number of steps is increased. The purpose of the present invention is to provide a method for producing a cellulose resin composite which can be reduced.

The above problems have been solved by the present invention shown below.

(1) A method for producing a cellulose resin composite containing cellulose and a resin, which comprises kneading cellulose, a resin, polyvinyl alcohol, and an acid-modified polyolefin in a water-containing state.

(2) The method for producing a cellulose resin composite according to (1) above, wherein the ratio of water / polyvinyl alcohol at the start of kneading is 10 / 2.0 or more on a mass basis.

(3) The method for producing a cellulose resin composite according to (1) above, wherein the ratio of water / polyvinyl alcohol at the start of kneading is 10 / 0.1 to 10 / 1.8 on a mass basis.

(4) The method for producing a cellulose resin composite according to any one of (1) to (3) above, wherein the cellulose is cellulose in a state of being defibrated in water.

(5) The method for producing a cellulose resin composite according to any one of (1) to (4) above, wherein the polyvinyl alcohol is an aqueous solution of polyvinyl alcohol.

In the present invention, in the method for producing a cellulose resin composite capable of obtaining a cellulose resin composite having good dispersibility of cellulose and capable of exhibiting a high elastic modulus, heat treatment of the molded product is unnecessary and the number of steps is reduced. It is possible to provide a method for producing a cellulose resin composite capable of this.

The method for producing a cellulose resin composite of the present invention is characterized by kneading cellulose, a resin, polyvinyl alcohol, and an acid-modified polyolefin in a water-containing state.

In the present invention, the resin to be composited with cellulose includes polyolefins such as polyethylene and polypropylene; polystyrene; acrylic resins typified by polymethyl methacrylate; halogen-based resins such as chlorinated polyolefins and polyvinyl chlorides; and thermosetting resins. Therefore, a resin or the like that can be kneaded at a relatively low temperature can be mentioned. Among these, polyolefin is a preferable resin. Further, polypropylene having high heat resistance and low specific gravity; a block copolymer of polypropylene and polypropylene; a copolymer of α-olefin and polypropylene, etc. are more preferable resins.

In the present invention, the cellulose is made from wood pulp obtained from coniferous trees, broadleaf trees, etc .; recycled paper pulp thereof; cotton and linter obtained from cotton, straw obtained from rice, bamboo obtained from bamboo, and Manila hemp. Non-wood pulps such as abaca obtained, jute obtained from Indian hemp, hemp obtained from hemp; and pulps using serial fibers discarded during food processing can be mentioned.

The pulp is one of cellulose, lignin, hemicellulose, oil, etc. contained in a molded product of a plant, excluding lignin and oil, or a pulp having a minimized content of hemicellulose. Depending on the application, it is bleached and whitened. The fiber diameter of the pulp is preferably 15 to 500 μm, and the fiber length is preferably 1 mm to 20 mm. These pulps are chemically or mechanically pulverized into fine particles of 1 mm or less, and fine microfibrillated celluloses partially nanocellulose can also be used.

Such pulp can be defibrated in water, dehydrated and used as a pulp defibrated product in order to preserve fiber length and crystallinity. In the case of pulps such as linter, cotton, DP and DKP having a low hemicellulose content, the water content of the pulp defibrated product is preferably 40% by mass to 80% by mass, and in the case of kraft pulp having a high hemicellulose content, the water content. Is preferably 60% by mass to 90% by mass. Further, in the case of microfibrillated cellulose, a higher water content is preferable, and it is preferably 70% by mass to 95% by mass. As a method for producing such a pulp defibrated product in a state of being defibrated in water, first, the raw material pulp sheet is defibrated in water with a stirrer such as a pulper, press-dehydrated with a mesh or the like, and then the fibers are defibrated. There are a method of drying while using a centrifuge, and a method of bringing a predetermined water content to a predetermined state with a centrifuge.

On the other hand, a method of mechanically crushing a raw material pulp sheet and using this as a fluff is also known. This method has a problem of a decrease in fiber length and a decrease in crystallinity due to an impact during pulverization, but it is advantageous in terms of cost because the treatment can be performed without containing water. In this case, a predetermined amount of water is contained in accordance with the polyvinyl alcohol aqueous solution or polyvinyl alcohol powder added at the time of kneading.

The acid-modified polyolefin dissolves polypropylene, polyethylene, a block copolymer of polyethylene and polypropylene, a block copolymer of polyethylene and α-olefin, a copolymer of polypropylene and α-olefin, and the like in a solution. Alternatively, it is a polyolefin synthesized by solidifying it, adding a radical generator and maleic anhydride, radicalizing the main chain of polyolefin, and adding maleic anhydride to the main chain. Since the main chain may be cleaved during the reaction, the amount of maleic anhydride added is preferably 0.1% by mass to 5% by mass of the whole. Known examples of such materials include Modic (registered trademark) manufactured by Mitsubishi Chemical, Admer (registered trademark) manufactured by Mitsui Chemicals, Youmex (registered trademark) manufactured by Sanyo Chemical Industries, and Hardlen (registered trademark) manufactured by Toyobo. ing.

As the acid-modified polyolefin, a copolymer of maleic anhydride and α-olefin can also be used. The copolymer of maleic anhydride and α-olefin has 5 or more carbon atoms, preferably 10 to 100 carbon atoms, and is an unsaturated α-olefin mixture obtained as a low polymer of ethylene of one or more kinds. It is a copolymer obtained by radically polymerizing maleic anhydride and maleic anhydride using a peroxide. The content of maleic anhydride is preferably 1% by mass to 15% by mass, more preferably 8% by mass to 12% by mass, based on the copolymer of maleic anhydride and α-olefin. The copolymer of maleic anhydride and α-olefin is characterized in that the content of maleic anhydride is higher than that of other acid-modified polyolefins. Since the acid-modified polyolefin contains maleic anhydride as a polymerization component, it can be unevenly distributed on the surface of highly hydrophilic cellulose, and the alkyl group of the (α-) olefin acts as a hydrophobic functional group. It enhances the affinity for resins such as polypropylene.

When the acid-modified polyolefin is an acid-modified polyolefin other than a copolymer of maleic anhydride and α-olefin, the amount added thereof is preferably 0.5% by mass to 5% by mass with respect to the total amount of the cellulose resin composite. %, More preferably 0.7% by mass to 3% by mass. When the acid-modified polyolefin is a copolymer of maleic anhydride and α-olefin, it is preferably 0.1% by mass to 1% by mass, and more preferably 0.2% by mass to 0.7. It is mass%.

The polyvinyl alcohol in the present invention is a water-soluble polymer obtained as a hydrolyzed (saponified) product of vinyl acetate. As the polyvinyl alcohol, various polyvinyl alcohols such as a low saponified product, a partially saponified product, and a completely saponified product are known. In addition, various polyvinyl alcohols such as polyvinyl alcohol having a functional group such as carboxylic acid, sulfonic acid, quaternary ammonium salt, polyethylene oxide group and acetoacetyl group, and polyvinyl alcohol copolymer with ethylene, butene, butenediol and the like can be used. Are known. These polyvinyl alcohols are dissolved in warm water to form a crystalline film after drying, and are crosslinked with aldehyde compounds such as urea, melamine, phenol resin, boric acid, borax, acetaldehyde, butyraldehyde, and glyoxyphosphate. You can also. Known examples of such polyvinyl alcohol include Kuraray Poval manufactured by Kuraray, Excelval (registered trademark), and Gosenex (registered trademark) manufactured by Nippon Synthetic Chemistry.

In the present invention, at the time of kneading, the polyvinyl alcohol is added as a powder or as an aqueous solution of polyvinyl alcohol in the presence of water heated to 90 ° C. to 100 ° C. When charged as powder, if the amount of heated water is small, polyvinyl alcohol may remain in an insoluble state. In the present invention, the water-containing state means a state in which the ratio of water / polyvinyl alcohol at the start of kneading is 10 / 2.0 or more on a mass basis. The ratio of water / polyvinyl alcohol at the start of kneading is preferably 10 / 0.1 to 10 / 1.8, more preferably 10 / 0.5 to 10 / 1.5. If the temperature range in which the resin is melted can be reached under these conditions, the polyvinyl alcohol is in a melted state, the water in the kneading system disappears, and the polyvinyl alcohol forms a film on the highly hydrophilic cellulose surface. The content of polyvinyl alcohol (in terms of solid content) is preferably 1% by mass to 20% by mass, more preferably 2% by mass to 15% by mass, based on cellulose.

If the content of cellulose is too small, the effect will not be exhibited, and if it is too large, the moldability will be deteriorated. Therefore, the content of cellulose is preferably 5% by mass to 60% by mass, more preferably, based on the total amount of the cellulose resin composite. It is preferably 10% by mass to 55% by mass. Further, when it is used as a masterbatch in which the resin is added again and kneaded in the latter stage of the manufacturing stage, it is preferably 40% by mass to 90% by mass, more preferably 50% by mass to 80% by mass. is there.

In addition to this, the cellulose resin composite of the present invention has, as an additive, a nucleating agent that promotes crystallization of polyolefin, and an antioxidant that suppresses deterioration due to oxygen oxidation and ultraviolet rays and imparts stability over time. , UV inhibitor, etc. can be used together.

In the method for producing a cellulose resin composite of the present invention, cellulose, resin, polyvinyl alcohol, and acid-modified polyolefin are kneaded in a water-containing state, and a biaxial kneader, a Henschel mixer, or the like can be used for kneading. In the present invention, since the kneading is carried out in a water-containing state, it is necessary to let the steam generated from the kneading field escape, so it is preferable to use a twin-screw kneader with a vent. The kneading temperature is preferably near the melting point of the resin or higher, and more preferably 190 ° C. to 230 ° C. However, in a twin-screw kneader with a vent, since cellulose and the resin are kneaded after the resin is melted, water may be removed in the early stage of kneading, and polyvinyl alcohol may not be melted in some cases. In such a case, it is preferable to have an induction zone for premixing in the temperature range of 90 ° C. to 100 ° C. in advance, and further, it is difficult for water vapor to escape from the kneading site, and the kneading has a highly airtight pressure-resistant specification. It is preferable to use the device. As a kneading machine satisfying such a pressure-resistant specification, for example, a batch-type sealed kneading device described in Pamphlet 2004/076044 is known. This device can store water and water vapor in the kneading plant until just before the cellulose is dispersed and before entering the process of melting the polyolefin, and can dissolve polyvinyl alcohol. The cellulose resin composite obtained by kneading can be made into a molded product such as a press molded product, an extrusion molded product, or an injection molded product by a molding machine such as a press molding machine, an extrusion molding machine, or an injection molding machine.

In Patent Document 4 (Japanese Unexamined Patent Publication No. 2012-236906), a step A in which cellulose and a water-soluble resin are mixed and dried to obtain a mixture, and the obtained dry mixture is subjected to a thermoplastic resin and acid modification. A cellulose resin composite is produced by a production method having a step B of adding polyolefin and melt-kneading. In Example 1 of Patent Document 4, since a dry mixture having a water content of 5% by mass was obtained in step A, the ratio of water / polyvinyl alcohol in step B was 10/32 on a mass basis. It is not included in the water content state in the invention. In Patent Document 4, the cellulose resin composite is obtained by two steps as described above, but in the present invention, cellulose, resin, polyvinyl alcohol, and acid-modified polyolefin are kneaded in a water-containing state. A cellulose resin composite can be obtained in one step.

Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

(Making cellulose (pulp) defibrated products)
The linter pulp sheet was immersed in water, mixed at a concentration of 3% by mass, and further dehydrated with a centrifuge to prepare a pulp defibrated product 1 having a cellulose content of 50% by mass (= water content of 50% by mass). The average fiber length was 1.2 mm. Pulp defibrated product 1 is cellulose (pulp) in a state of being defibrated in water.

The linter pulp sheet was roughly crushed with a hammer crusher manufactured by Makino Sangyo, and then dried and defibrated with a DD-2 type crusher manufactured by Makino Sangyo to obtain pulp defibrated product 2. The average fiber length was 1.0 mm.

(Examples 1 to 6 and Comparative Examples 1 to 8)
Cellulose (pulp defibrated product 1), acid-modified polypropylene (acid-modified polypropylene (PP), manufactured by Toyo Boseki, trade name: Hardlen (registered trademark) H1000P), polyvinyl alcohol (PVA, manufactured by Nippon Synthetic Chemicals, trade name: Gosenex (registered trademark)) Z410) and resin (polypropylene (PP), manufactured by Nippon Polypro, trade name: BC06C), and as an antioxidant, manufactured by BASF, trade name: Irganox (registered trademark) 1010, as a nucleating agent, manufactured by ADEKA. Name: Adecaster (registered trademark) NA-27 was kneaded at the content (mass basis) in Table 1 using a batch-type closed kneader to prepare a cellulose resin composite.

(Example 7)
Cellulose (pulp defibrated product 2), acid-modified polypropylene (acid-modified polypropylene (PP), manufactured by Toyo Boseki, trade name: Hardlen (registered trademark) H1000P), polyvinyl alcohol (PVA, manufactured by Nippon Synthetic Chemicals, trade name: Gosenex (registered trademark)) Z410) and resin (polypropylene (PP), manufactured by Nippon Polypro, trade name: BC06C), and as an antioxidant, manufactured by BASF, trade name: Irganox (registered trademark) 1010, as a nucleating agent, manufactured by ADEKA. Name: Adecaster (registered trademark) NA-27, 30 parts of water was kneaded at the content (mass basis) shown in Table 1 using a batch-type closed kneader to prepare a cellulose resin composite.

(Comparative Example 9 and Comparative Example 10)
In Comparative Example 9, 200 parts (100 parts in terms of pulp (solid content)) of 143 parts of a polyvinyl alcohol aqueous solution having a concentration of 7% by mass (10 parts in terms of powder (solid content)) was mechanically added to 1 pulp defibrated product. After being made into a composite of pulp defibrated product 1 with a solid content concentration of 32% by mass, polyvinyl alcohol, and water, it was dried at 120 ° C. for 4 hours using a hot air dryer to dry the water. It was removed to obtain a composite of pulp defibrated product 1 and polyvinyl alcohol. In the composite of pulp defibrated product 1 and polyvinyl alcohol, pulp defibrated product 1 was solidified, so after coarse crushing, acid-modified polyolefin, resin, antioxidant and nucleating agent were added according to the content (mass basis) in Table 1. Then, it was kneaded using a batch type closed kneading device to prepare a cellulose resin composite. Further, in Comparative Example 10, 143 parts of a polyvinyl alcohol aqueous solution having a concentration of 7% by mass (10 parts in terms of powder (solid content)) was slowly added to 100 parts of the pulp defibrated product 2 while being mechanically mixed. After preparing a composite of pulp defibrated product 2 / polyvinyl alcohol / water having a solid content concentration of 45% by mass in advance, it is dried at 120 ° C. for 4 hours using a hot air dryer to remove water to remove pulp defibrated product 2 / polyvinyl alcohol. It was made into a complex of. Similar to Comparative Example 9, the composite of pulp defibrated product 2 and polyvinyl alcohol was roughly pulverized, and then acid-modified polyolefin, resin, antioxidant and nucleating agent were added according to the content (mass basis) in Table 1. , Kneaded using a batch type closed kneading device to prepare a cellulose resin composite.

(Evaluation)
A dumbbell piece (molded body) having a width of 10 mm and a thickness of 4 mm was produced according to JIS standard K7171. The flexural modulus of the dumbbell piece (heat-treated body) heat-treated at 150 ° C. for 3 hours and the dumbbell piece (non-heat-treated body) stored at 24 ° C. for 3 days was determined by the universal material testing machine (TSE Co., Ltd., device name: Measurements were made using Autocom (registered trademark, AutoCOM) AC-100) under the conditions of a test speed of 2 mm / min and a distance between fulcrums of 64 mm, and the results are shown in Table 1. Further, in each Example and Comparative Example, the percentage of the flexural modulus of the non-heat-treated product when the flexural modulus of the heat-treated body is 100% is shown in Table 1 as "reproducibility of the flexural modulus".

Further, with respect to the molded articles obtained in Example 1 and Example 2 and Comparative Examples 2 and 3, the heat absorption reaction calorie of crystal melting near 160 ° C. was measured using DSC, and the calorific value of complete crystal melting of polypropylene was measured. The crystallinity of polypropylene in the molded product was measured at 209 J / g, and this is shown in Table 1. For the measurement of DSC, a device name: DSC8500 manufactured by PerkinElmer was used.

In Comparative Example 2 in which the resin alone was kneaded without containing cellulose, acid-modified polyolefin and polyvinyl alcohol, when the molded product was heat-treated, the crystallinity was improved as compared with the case where there was no heat treatment, and as a result, the crystallinity was improved. , The flexural modulus is also improved. Further, when the shape of the molded body was observed, it is presumed that the surface transparency of the heat-treated body was improved and the number of microcrystals was increased. Further, also in Comparative Example 3 in which cellulose, acid-modified polyolefin, and resin were kneaded without containing polyvinyl alcohol, the crystallinity was improved when the molded product was heat-treated as compared with the case where there was no heat treatment. As a result, the flexural modulus is also improved. In addition, the reproducibility of the flexural modulus is also improved as compared with Comparative Example 2. On the other hand, in Example 1 in which cellulose, acid-modified polyolefin, polypropylene alcohol and resin are kneaded in a water-containing state and the cellulose content is 15% by mass, a non-heat-treated product is compared with Comparative Example 3 in which the cellulose content is equal. The degree of crystallinity of polypropylene is slightly improved, the flexural modulus of the non-heat-treated body and the heat-treated body is also improved, and the reproducibility of the flexural modulus is also improved. When cellulose, acid-modified polyolefin, polyvinyl alcohol and resin are kneaded in a water-containing state and Examples 1 and 2 in which the cellulose content is equal to 15% by mass are compared, Example 2 having a higher polyvinyl alcohol content is higher. , The reproducibility of flexural modulus has been improved.

Cellulose, acid-modified polyolefin, polyvinyl alcohol and resin are kneaded in a water-containing state, and in Example 3 in which the content of cellulose is 30% by mass, cellulose, acid-modified polyolefin and resin are kneaded without containing polyvinyl alcohol. Compared with Comparative Example 5 in which the cellulose content was 30% by mass, the flexural modulus of the non-heated body and the heat-treated body was also improved, and the reproducibility of the flexural modulus was also improved. In particular, in Example 3, the crystallinity of polypropylene was also improved in both the heat-treated body and the non-heat-treated body. Cellulose, acid-modified polyolefin, polyvinyl alcohol and resin are kneaded in a water-containing state, and in Example 5 in which the content of cellulose is 45% by mass, cellulose, acid-modified polyolefin and resin are kneaded without containing polyvinyl alcohol. Compared with Comparative Example 8 in which the cellulose content was 45% by mass, the flexural modulus of the non-heated body and the heat-treated body was also improved, and the reproducibility of the flexural modulus was also improved.

In Comparative Example 1 in which cellulose, acid-modified polyolefin, polyvinyl alcohol and resin are kneaded in a non-hydrated state and the cellulose content is 15% by mass, polyvinyl alcohol is not contained and cellulose, acid-modified polyolefin and resin are in a non-hydrated state. The flexural modulus of the non-heat-treated body and the heat-treated body was the same as that of Comparative Example 4 in which the cellulose content was 15% by mass, but the reproducibility of the bending elastic modulus was slightly improved. There is. In Example 1 in which cellulose, acid-modified polyolefin, polyvinyl alcohol and resin are kneaded in a water-containing state and the cellulose content is 15% by mass, the reproducibility of flexural modulus is almost the same as that in Comparative Example 1. However, the flexural modulus of the non-heat-treated body and the heat-treated body was improved. Further, in Example 3 in which cellulose, acid-modified polyolefin, polyvinyl alcohol and resin are kneaded in a water-containing state and the cellulose content is 30% by mass, cellulose, acid-modified polyolefin, polyvinyl alcohol and resin are in a non-water-containing state. Compared with Comparative Example 6 in which the cellulose content was 30% by mass after kneading, the flexural modulus of the non-heated body and the heat-treated body was improved, and the reproducibility of the flexural modulus was also improved. That is, it was shown that the effect of improving the flexural modulus by polyvinyl alcohol is further enhanced by kneading in a water-containing state. This is because the polyvinyl alcohol dissolves during kneading in a water-containing state, and then the polyvinyl alcohol precipitates on the surface of the cellulose to form a film in the process of draining the water, thereby improving the dispersibility between the cellulose and the resin. it is conceivable that.

Comparing Examples 3, 4, 6 and 7 in which cellulose, acid-modified polyolefin, polyvinyl alcohol and resin were kneaded in a water-containing state, the ratio of water to polyvinyl alcohol at the start of kneading was found in Examples 3 and 7. It is 10 / 1.0, 10 / 0.43 in Example 4, and 10 / 0.75 in Example 6. The reproducibility of the flexural modulus and the flexural modulus of the molded product obtained in Examples 3, 4, 6 and 7 are almost the same, and the effect of the present invention can be obtained by kneading in the water-containing state of the present invention. It has been shown. That is, the water at the start of kneading is the water contained in the pulp defibrated product 1 (Examples 3 and 4), the water in the polyvinyl alcohol aqueous solution (Examples 4 and 6), and the added water (Example 7). It may be either. In consideration of mass productivity, Examples 3 and 6 are preferable to Examples 4 and 7 in which the kneading time is long to remove water.

In Example 3 in which cellulose, acid-modified polyolefin, polyvinyl alcohol and resin were kneaded in a water-containing state, compared with Comparative Example 7 in which cellulose, polyvinyl alcohol and resin were kneaded in a water-containing state without containing acid-modified polyolefin, they were not kneaded. The flexural modulus of the heat-treated body and the heat-treated body was improved, and the reproducibility of the flexural modulus was also improved. This is considered to be due to poor dispersion of cellulose in Comparative Example 7 which does not contain the acid-modified polyolefin. That is, in the present invention, the crystallinity of polypropylene is improved by kneading cellulose and polyvinyl alcohol in a water-containing state while ensuring the dispersibility of cellulose with acid-modified polyolefin, so that a high elastic modulus can be exhibited. It is thought that it is.

In Comparative Examples 9 and 10, with reference to Patent Document 4 (Japanese Unexamined Patent Publication No. 2012-236906), step A in which cellulose (pulp) and polyvinyl alcohol are mixed and dried to obtain a mixture, and the obtained dry mixture On the other hand, a cellulose resin composite was prepared by a production method having a step B of adding a resin, an acid-modified polyolefin and the like and melt-kneading. From the comparison between Example 6 and Comparative Example 9, in Comparative Example 9 in which the pulp and polyvinyl alcohol were mixed and then subjected to the drying step, the flexural modulus of the non-heat-treated body was lower than that in Example 6, and bending was performed. The reproducibility of the elastic modulus is reduced. It is considered that this is because in Comparative Example 9, polyvinyl alcohol was unevenly distributed, and this uneven distribution could not be eliminated even in step B, and the dispersibility of the pulp was deteriorated. Further, from the comparison between Example 4 and Comparative Example 10, in Comparative Example 10 in which the pulp and polyvinyl alcohol were mixed and then subjected to the drying step, the flexural modulus of the non-heat-treated body was low as in Example 9. , The reproducibility of the flexural modulus was lowered. From the above results, in Comparative Example 9 and Comparative Example 10, two steps are required, whereas in Example 6 and Example 4, a cellulose resin composite can be obtained in one step, and in Example. In 6 and Example 4, the cellulose-resin composite having a high elastic modulus can be obtained because it is in a water-containing state at the start of kneading and water is present at the time of kneading the cellulose and the resin.

The cellulose resin composite of the present invention can be widely used in the fields of electricity / electronics, machinery, automobiles, building materials and the like.

Claims (4)

In the method for producing a cellulose resin composite containing cellulose and a resin, the resin is melted in a water-containing state in which the ratio of water / polyvinyl alcohol at the start of kneading is 10 / 2.0 or more on a mass basis . Cellulose resin composite by reaching a temperature range and kneading cellulose, resin, polyvinyl alcohol, and acid-modified polyolefin (except that adding both polyvinyl alcohol and resin to a solvent that dissolves and stirring). A method for producing a cellulose resin composite, which comprises obtaining. The method for producing a cellulose resin composite according to claim 1, wherein the ratio of water / polyvinyl alcohol at the start of kneading is 10 / 0.1 to 10 / 1.8 on a mass basis. The method for producing a cellulose resin composite according to claim 1 or 2, wherein the cellulose is cellulose in a state of being defibrated in water. The method for producing a cellulose resin composite according to any one of claims 1 to 3, wherein the polyvinyl alcohol is an aqueous solution of polyvinyl alcohol.