JP6683395B2 - Cellulose resin composite - Google Patents

Description

  The present invention relates to a cellulose resin composite.

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

  As one of the uses of cellulose, a cellulose resin composite compounded with a polyolefin general-purpose resin such as polyethylene (PE) or polypropylene (PP) is used as a structure such as a press-molded body, an extrusion-molded body, or an injection-molded body. There are uses. However, the surface of the cellulose crystals having high hydrophilicity and the polyolefin having strong hydrophobicity have a low affinity, and the cellulose crystals cannot be in a good dispersed state in the polyolefin, resulting in agglomeration and It was difficult to obtain a high cellulose resin composite.

  As a method for improving this, there are two methods, that is, a method of modifying the surface of cellulose to increase the affinity with the resin, and a method of adding a material that increases the affinity with cellulose to the resin. However, the former method is not a practical method because the cost is high because the cellulose is chemically modified in advance. On the other hand, as a material for increasing the affinity with cellulose, 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 has improved strength characteristics. However, it cannot be said to be sufficient yet, and means for further improving the strength characteristics are required.

Japanese Patent Publication No. 7-5751 Japanese Patent No. 5433949

  An object of the present invention is to provide a cellulose resin composite having excellent strength characteristics.

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

(1) In a cellulose resin composite containing cellulose and a resin, the cellulose resin composite contains at least one polymer selected from the group consisting of a polymer containing carboxylic acid anhydride as a polymer component and a monoaldehyde and a dialdedo. A cellulosic resin composite, characterized in that it contains cellulose to which an aldehyde has been added.

(2) The cellulose resin composite according to (1) above, wherein at least one aldehyde selected from the group consisting of monoaldehyde and dialdedo is an aldehyde having 5 or more carbon atoms.

  The cellulose resin composite according to (1) or (2) above, wherein the aldehyde group of at least one aldehyde selected from the group consisting of monoaldehyde and dialdedo is acetalized with a lower alcohol.

  In the present invention, a cellulose resin composite having excellent strength characteristics can be obtained.

  The cellulose resin composite of the present invention contains a polymer containing cellulose and a resin and further containing at least one aldehyde selected from the group consisting of monoaldehyde and dialdedo, and a polymer containing carboxylic acid anhydride as a polymer component. It is characterized in that it contains cellulose.

  In the present invention, examples of the resin include polyethylene, polypropylene, block polymers of polyethylene and polypropylene, copolymerized polyolefins of α-olefins such as butene, 1-hexene, 1-octene and polypropylene, and the like. Preferred resins include polypropylene and polypropylene containing a small amount of polyethylene.

  In the present invention, as the cellulose, wood-based pulp obtained from softwood, hardwood, etc .; recycled paper pulp which is a recycled product of these; cotton and linters obtained from cotton, straw obtained from rice, bamboo obtained from bamboo and Manila hemp. Non-wood pulp such as obtained abaca, jute obtained from Indian hemp, hemp obtained from hemp, and pulp using cereal fibers discarded at the time of food processing.

  Pulp refers to cellulose, lignin, hemicellulose, oil or the like contained in a plant structure, from which lignin or oil has been removed, or the content of hemicellulose is minimized. Depending on the application, it is bleached and whitened. The fiber diameter of the pulp is preferably 15 μm or more and 500 μm or less, and the fiber length is preferably 1 mm or more and 20 mm or less. Those obtained by chemically or mechanically pulverizing these pulps into fine particles of 1 mm or less, or fine microfibrillated cellulose partially converted into nanocellulose can also be used.

  In the present invention, the polymer containing carboxylic acid anhydride as a polymer component is an acid-modified polyolefin or a copolymer of maleic anhydride and α-olefin. In the present invention, the polymer containing carboxylic acid anhydride as a polymerization component has a property of being compatible with polyolefin.

  Acid-modified polyolefin is polypropylene or polyethylene, or polypropylene / polyethylene block polymer or polyethylene / α-olefin block polymer, which is dissolved in solution or solidified, and a radical generator and maleic anhydride are added. Then, the polyolefin main chain is radicalized and maleic anhydride is added to the main chain to synthesize the polyolefin. Since the main chain may be cleaved during the reaction, the addition amount of maleic anhydride is preferably 0.1% by mass or more and 5% by mass or less of the whole. Known examples of such materials include MODIC (registered trademark) of Mitsubishi Chemical, Admer (registered trademark) of Mitsui Chemicals, Yumex (registered trademark) of Sanyo Chemical Industries, and Hardlen (registered trademark) of Toyobo. Hereinafter, the acid-modified polyolefin may be described as “acid-modified polypropylene” or “acid-modified PP”.

  The copolymer of maleic anhydride and α-olefin is a mixture of unsaturated α-olefins having 5 or more carbon atoms, preferably about 10 to 100, obtained as a low polymer of ethylene, alone or in plural kinds. It is a radical copolymer using maleic anhydride and peroxide. The content of maleic anhydride is preferably 1% by mass or more and 15% by mass or less, more preferably 8% by mass or more and 12% by mass or less, 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 the acid-modified polyolefin. Due to this feature, 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 to enhance the affinity for resins such as polypropylene. Hereinafter, the copolymer of maleic anhydride and α-olefin may be referred to as an “acid-modified copolymer”.

  At least one aldehyde selected from the group of monoaldehyde and dialdedo will be described. Monoaldehyde and dialdehyde have relatively low boiling points, and volatilized aldehyde reacts rapidly with the amino groups of proteins, stimulating the eyes and throat, so low-boiling aldehydes such as formaldehyde, acetaldehyde, and glyoxal are Not used in the present invention. In the present invention, an aldehyde having 5 or more carbon atoms can be preferably used. Since the reactivity decreases as the carbon number of the aldehyde increases, the upper limit of the carbon number is preferably 16.

  Specific examples of the monoaldehyde having 5 or more carbon atoms include octanal, nanonal, melonal, undecanal, hexahydrobenzaldehyde, and 3,7-dimethyl-2,6-octadienal. Further, in the present invention, acetalized products of these monoaldehydes and lower alcohols can also be used, and examples thereof include octanal dimethyl acetal and 2-heptyl-1,3-dioxolane.

  Specific examples of the dialdehyde having 5 or more carbon atoms include octane-1,8-dione, 2-methyloctane-1,8-dione and nonane-1,9-dione. Further, in the present invention, acetalized products of these dialdehydes and lower alcohols can also be used, and examples thereof include 2,2 ′-(1,7-pentanediyl) -bis-1,3-dioxolane.

  Lower alcohols are monohydric alcohols such as methanol, ethanol, propanol and butanol and dihydric alcohols such as ethylene glycol, propylene glycol, 1,3-propanediol and 1,3-butanediol, which react with aldehydes. The compound is a compound that undergoes acetalization. In the present invention, the lower alcohol preferably has 1 to 4 carbon atoms.

  In the present invention, the aldehyde is added to the cellulose by acetalization with the hydroxyl group at the 6-position in the glucose unit of the cellulose skeleton using a polymer containing carboxylic acid anhydride as a polymerization component as a catalyst to make the cellulose surface hydrophobic. As a result, the effect of improving the adhesion between cellulose and polyolefin is achieved.

  The cellulose resin composite of the present invention is obtained by kneading at least a cellulose, a resin, a polymer containing carboxylic acid anhydride as a polymerization component, and an aldehyde. If the amount is too small, it will not be effective against the total amount of the cellulose resin complex, and if it is too large, it may cause rust on the metal surface during kneading or molding, or strongly adsorb to the metal surface to contaminate the kneader Therefore, the content of the acid-modified polypropylene is preferably 0.5% by mass or more and 5% by mass or less, and the content of the acid-modified copolymer is preferably 0.1% by mass or more and 1% by mass or less. More preferably, the content of the acid-modified polypropylene is 0.7% by mass or more and 3% by mass or less, and the content of the acid-modified copolymer is 0.2% by mass or more and 0.7% by mass or less.

  When the amount is too small, the effect is not exhibited, and the aldehyde remains in the resin when used in a large amount based on the total amount of the cellulose resin complex. Therefore, the aldehyde content is preferably 0.01% by mass or more and 1% by mass or more. It is below, and more preferably about 0.1% by mass or more and about 0.7% by mass.

  As the content of cellulose, if it is too small, the effect is not exhibited, and if it is too large, the moldability is deteriorated. Therefore, it is preferably 5% by mass or more and 50% by mass or less with respect to the total amount of the cellulose resin composite. More preferably, it is 10% by mass or more and 40% by mass or less. Further, when it is used as a masterbatch in which a resin is added again and kneaded in the latter stage of the production stage, it is preferably 40% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 80% by mass or less. It is the following.

  The cellulose resin composite of the present invention is obtained by kneading cellulose, a resin, a polymer containing carboxylic acid anhydride as a polymerization component, and an aldehyde with a biaxial kneader, a Henschel mixer, or the like. However, when the cellulosic raw material contains water, it is necessary to release the steam generated from the kneading field, so it is preferable to use a biaxial kneader with a vent. The kneading temperature is preferably around the melting point of the resin or higher, and more preferably 190 ° C. or higher and 230 ° C. or lower. The cellulose resin composite obtained by the kneading can be made into a structure such as a press-molded body, an extrusion-molded body, an injection-molded body by a molding machine such as a press-molding machine, an extrusion-molding machine, and an injection-molding machine.

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

(Preparation of cellulose (pulp defibrated product))
The linter pulp sheet was immersed in water, mixed at a concentration of 3% by mass, and further dehydrated by a centrifuge to prepare a pulp defibrated product 1 having a cellulose content of 50% by mass. The average fiber length was 1.2 mm. After roughly crushing the linter pulp sheet with a hammer crusher manufactured by Makino Sangyo, dry defibration was performed using a DD-2 type crusher manufactured by Makino Sangyo to obtain a pulp defibrated product 2. The average fiber length was 1.0 mm. Next, the pulp defibrated product 1 and the pulp defibrated product 2 were mixed with a kneader so that the ratio was 1: 2 to prepare a non-coagulated pulp defibrated product 3. The water content was 78% by mass, and the average fiber length was 1.1 mm.

(Example 1)
The following materials were kneaded with a biaxial kneader with a vent to produce a cellulose resin composite. The maximum temperature during kneading was 220 ° C.

Pulp defibrated product 3 (water-containing state) 19.2 parts by mass acid-modified polypropylene (manufactured by Toyobo, trade name: HARDREN (registered trademark) H1000P)
1.0 part by weight polypropylene (prime polymer, homotype PP, trade name: BC06C)
83.5 parts by mass Octanal dimethyl acetal 0.5 parts by mass

  Next, according to JIS standard K7171, a dumbbell piece with a width of 10 mm and a thickness of 4 mm was prepared, and a universal material testing machine (TSE, device name: Autocom (registered trademark, AutoCOM) AC-100) was used. The bending characteristics were measured at a test speed of 2 mm / min and a fulcrum distance of 64 mm, and the results are shown in Table 1.

(Examples 2 to 5 and Comparative Examples 1 to 4)
In Examples 2 to 5 and Comparative Examples 1 to 4, the materials and the contents (on a mass basis) shown in Table 1 were kneaded in the same manner as in Example 1 using a vented biaxial kneader to give a cellulose resin. A composite was made. In addition, a test piece was prepared in the same manner as in Example 1, the bending characteristics thereof were measured, and the results are shown in Table 1.

  Polymers containing carboxylic acid anhydride as a polymer component and an aldehyde are added In Examples 1 to 5 containing cellulose, a polymer containing a carboxylic acid anhydride as a polymer component and an aldehyde are added. In Comparative Example 1 not containing both celluloses, Comparative Example 2 containing only a polymer containing carboxylic acid anhydride as a polymer component, and Comparative Examples 3 and 4 containing only cellulose to which an aldehyde is added. In comparison, both the bending strength and the bending elastic modulus are improved, and the bending elastic modulus is improved in the examples as compared with the comparative example, and the cellulose resin composite contains carboxylic acid anhydride as a polymer component. The effect by containing both the polymer and the cellulose to which the aldehyde was added was clarified.

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

Claims (3)

In a cellulose resin composite containing cellulose and resin,
The above-mentioned cellulose includes a cellulose (excluding wood flour) to which at least one aldehyde selected from the group of C5 or more monoaldehyde and dialdedo is added,
The resin contains at least one resin selected from the group of polyethylene, polypropylene, block polymers of polyethylene and polypropylene, and copolymerized polyolefins of α-olefin and polypropylene,
The cellulose resin complex further, a cellulose resin complexes characterized by containing a high-molecular containing carboxylic anhydride as the polymer component. Cellulose resin composite according to claim 1, wherein the aldehyde group of at least one aldehyde selected from the group consisting of 5 or more mono-aldehydes and Jiarudedo carbon is acetalized with a lower alcohol. The cellulose resin composite according to claim 1 or 2, wherein the polymer containing carboxylic acid anhydride as a polymer component is an acid-modified polyolefin or a copolymer of maleic anhydride and α-olefin.