JP2008024795A - Microfibrillated cellulose-containing resin molded product with improved strength - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin molded product which contains a microfibrillated cellulose and has an improved elastic modulus and strengths. <P>SOLUTION: The resin molded product is obtained by molding a kneaded product containing the microfibrillated cellulose and a resin, provided that the microfibrillated cellulose accounts for 4-15 wt.% of the entire molded product. The relative strength of the resin molded product against a molded product which contains no microfibrillated cellulose but is molded through the same method is ≥1.10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a resin molded article containing microfibrillated cellulose and having excellent strength and a method for producing the same.

  The cell walls of all plants are based on high-strength nanofibers with a width of about 4 nm called cellulose microfibrils. Microfibrillated cellulose is a nanofiber consisting of extended chain crystals obtained by defibrating plant fibers such as pulp to the level of cellulose microfibrils. Further, microfibrillated cellulose derived from bacteria (mainly acetic acid bacteria) is also known, and Nata de Coco is well known as a food utilizing this. It is known that microfibrillated cellulose can be generally produced by grinding or beating a cellulosic fiber with a refiner, a homogenizer, or the like (see, for example, Patent Document 1). Microfibrillated cellulose is light, strong, and highly biodegradable, so it can be used in a wide range of fields, including housings for home appliances such as personal computers and mobile phones, office equipment such as stationery, sports equipment, transportation equipment, and building materials. Application is expected.

Attempts have been made to utilize such mechanical properties of microfibrillated cellulose in the field of resins that are already widely used. For example, for the purpose of improving the physical properties and functions of the resin and imparting new physical properties and functions, it has been attempted to mix and composite the microfibrillated cellulose with the resin. In particular, biodegradable resins have attracted attention from the viewpoint of environmental impact, and attempts have been made to mix and combine these biodegradable resins and microfibrillated cellulose. However, since the microfibrillated cellulose has a very small fiber diameter of 200 nm or less in many cases, aggregation and the like are much more likely to occur than ordinary cellulose fibers. For this reason, it is very difficult to disperse the microfibrillated cellulose in the resin, and it is difficult to obtain a uniform composite resin. In order to solve this, the fiber component is disentangled during melt-kneading the aliphatic polyester containing polylactic acid and the pretreated pulp and / or cellulosic fibers whose primary wall and secondary wall outer layer are damaged. A technique for uniformly dispersing microfibrillated cellulose in a resin by microfibrillation (see, for example, Patent Document 2), mixing microfibrillated cellulose and polylactic acid fiber, and making a sheet by papermaking A technique to create (see, for example, Patent Document 3) is known. However, the resin molded body obtained by these techniques has a higher elastic modulus than the original resin molded body, but has a low strength and is generally brittle.
Japanese Patent Publication No. 50-38720 JP 2005-42283 A JP 2003-211695 A

  Accordingly, an object of the present invention is to provide a microfibrillated cellulose-containing resin molded product that greatly improves not only the elastic modulus but also the original strength of the resin molded product.

The present inventor examined various methods for mixing microfibrillated cellulose and resin. By adopting a microfibrillated cellulose dispersion and a resin solution, the microfibrillated cellulose and the resin were uniformly distributed. It has been found that a mixed liquid is obtained, and a microfibrillated cellulose-containing resin that can be subjected to plastic working can be produced by kneading the mixture obtained by removing the solvent from the liquid.
Furthermore, this inventor also discovered that it became a molded object provided with the outstanding intensity | strength and elasticity modulus by shape | molding the microfibrillated cellulose containing raw resin manufactured by the said manufacturing method.

That is, the present invention relates to the following resin molded body and manufacturing method.
Item 1. A resin molded body obtained by molding a kneaded product containing microfibrillated cellulose and a resin,
The content of microfibrillated cellulose is 4 to 15% by weight of the whole molded body,
A resin molded body having a relative strength of 1.10 or more compared to the strength of a molded body molded by the same method except that the strength of the molded body does not include microfibrillated cellulose.
Item 2. Item 2. The resin molded product according to Item 1, wherein the content of microfibrillated cellulose is 5 to 15% by weight of the entire molded product.
Item 3. Item 3. The resin molded article according to Item 1 or 2, wherein the relative strength is 1.15 or more.
Item 4. Item 4. The resin molded article according to any one of Items 1 to 3, wherein the resin is at least one selected from the group consisting of biodegradable resins and aliphatic polyesters.
Item 5. Containing microfibrillated cellulose, comprising the steps of dispersing microfibrillated cellulose and dissolving resin in a solvent having microfibrillated cellulose dispersibility and resin solubility, mixing, and then removing the solvent. Manufacturing method of resin molding.
Item 6. Item 6. The method for producing a microfibrillated cellulose-containing resin according to Item 5, wherein the solvent is acetone.
Item 7. A method for producing a microfibrillated cellulose-containing resin molded article, comprising: mixing a solvent in which a resin is dissolved and a solvent in which microfibrillated cellulose is dispersed, and then removing the solvent.
Item 8. Item 8. The production method according to Item 7, wherein the solvent in which the resin is dissolved is dichloromethane, and the solvent in which the microfibrillated cellulose is dispersed is acetone.
Item 9. Item 9. The production method according to any one of Items 5 to 8, wherein the content of microfibrillated cellulose in the microfibrillated cellulose-containing resin molded product is 4 to 15% by weight.
Item 10. Item 10. The production method according to any one of Items 5 to 9, wherein the resin is at least one selected from the group consisting of biodegradable resins and aliphatic polyesters.
Item 11. Item 11. A microfibrillated cellulose-containing resin molded article produced by the method according to any one of Items 5 to 10.

  Methods for producing microfibrillated cellulose are known, and are generally produced by defibrating or refining cellulose by grinding or beating it with a refiner, high-pressure homogenizer, medium stirring mill, stone mortar, grinder or the like. It can also be produced by a known method such as the method described in JP-A-2005-42283. Commercial products can also be used. Cellulose is a plant (for example, wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp, recycled pulp, waste paper), animals (for example, ascidians), algae, microorganisms (for example, acetic acid bacteria (Acetobacter)), etc. Are known, but any of them can be used in the present invention. Preferred are plant and microorganism-derived cellulose fibers, and more preferred are plant-derived cellulose fibers.

  The average fiber diameter of the microfibrillated cellulose is preferably 4 nm to 400 nm, more preferably 4 nm to 200 nm, and even more preferably 4 nm to 100 nm. The average fiber length is preferably 50 nm to 50 μm, and more preferably 100 nm to 10 μm.

  In the present invention, the resin is not particularly limited, and can be used alone or in combination of two or more. For example, polylactic acid, vinyl chloride resin, vinyl acetate resin, polystyrene, ABS resin, acrylic resin, polyethylene, polyethylene terephthalate, polypropylene, fluororesin, polyamide resin, acetal resin, polycarbonate, fibrous plastic, polyglycolic acid, poly-3- Hydroxybutyrate, poly-4-hydroxybutyrate, polyhydroxyvalerate polyethylene adipate, polyester such as polycaprolactone, polypropiolactone, polyether such as polyethylene glycol, polyglutamic acid, polyamide such as polylysine, polyvinyl alcohol, polyurethane, etc. Thermoplastic resin: phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, diallyl phthalate resin, polyureta Resin, silicone resin, etc. can be used thermoplastic resins such as polyimide resin, but are not limited to be used in combination singly or two or more. Preferred are biodegradable resins, phenol resins, epoxy resins, acrylic resins, and aliphatic polyesters.

  Examples of biodegradable resins include L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, malic acid, ε-caprolactone, N-methylpyrrolidone, trimethylene carbonate, paradioxanone, 1,5-dioxepane-2 -Homopolymers such as ON, hydroxybutyric acid and valeric acid hydroxide, copolymers or mixtures of these polymers can be mentioned, and these can be used singly or in combination of two or more. Preferred biodegradable resins are polylactic acid and polycaprolactone, and more preferred is polylactic acid.

  Polylactic acid is not particularly limited, but a preferred number average molecular weight is 30,000 or more, preferably 100,000 or more. The upper limit of the number average molecular weight of polylactic acid is not particularly limited, but is usually 1,000,000 or less, preferably 500,000 or less. From the physical properties of the polylactic acid obtained, the molar ratio of L-form to D-form can be used in all compositions where L / D is 100/0 to 0/100. And it is preferable that L body is 95 mol% or more. The production method of polylactic acid is known and is not particularly limited, and examples thereof include a ring-opening polymerization method via lactide, a direct polycondensation method of lactic acid, and the like.

Preferred as the aliphatic polyester is (a) an aliphatic diol, (b) an aliphatic dicarboxylic acid and / or a functional derivative thereof, and (c) a bifunctional aliphatic hydroxy, if necessary, under the polyester production conditions. It is obtained by reacting a carboxylic acid and / or a derivative thereof, and more preferably obtained by carrying out this reaction in the presence of a germanium catalyst.
<(A) Aliphatic diol>
(A) Aliphatic diols (including alicyclic diols) are compounds having two hydroxyl groups, and preferred specific examples thereof are those represented by the following general formula (I).

HO—R ¹ —OH (I)
In the general formula (I), R ¹ is a divalent aliphatic hydrocarbon group, preferably an aliphatic hydrocarbon group having 2 to 11 carbon atoms, particularly preferably 2 to 6 carbon atoms. R ¹ may have a branched chain or a cycloalkylene group. R ¹ is preferably — (CH ₂ ) n — (where n is an integer of 2 to 11, preferably an integer of 2 to 6).

  (A) The aliphatic diol is not particularly limited, and specific examples thereof include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1 , 4-cyclohexanediol, 1,6-cyclohexanedimethanol and the like. These may be used alone or as a mixture of two or more.

  In view of the physical properties of the resulting aliphatic polyester, (a) the aliphatic diol is particularly preferably 1,4-butanediol.

<(B) Aliphatic dicarboxylic acid and / or derivative thereof>
(B) Aliphatic dicarboxylic acids (including alicyclic dicarboxylic acids) and / or derivatives thereof are represented by the following general formula (II), or their lower alkyl esters having 1 to 4 carbon atoms or their Such as anhydrides.

^{HOOC-R 2 -COOH ... (II} )
In general formula (II), R ² is a direct bond or a divalent aliphatic hydrocarbon group, preferably a divalent aliphatic hydrocarbon group having 2 to 11 carbon atoms, particularly preferably 2 to 6 carbon atoms. . R ² may have a branched chain or a cycloalkylene group. R ² is preferably — (CH ₂ ) m — (where m represents an integer of 0 or 1 to 11, preferably 0 or an integer of 1 to 6).

  Preferable specific examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, suberic acid, dodecanedioic acid and the like, and functional derivatives thereof include these acid anhydrides. It is done. These may be used alone or as a mixture of two or more. That is, you may use together within each group and / or between each group.

  From the viewpoint of the physical properties of the resulting aliphatic polyester, (b) the aliphatic dicarboxylic acid and / or its derivative is preferably succinic acid or succinic anhydride, or a mixture thereof with adipic acid.

<(C) Bifunctional aliphatic hydroxycarboxylic acid and / or derivative thereof>
(C) The bifunctional aliphatic hydroxycarboxylic acid (including alicyclic hydroxycarboxylic acid) and / or the bifunctional aliphatic hydroxycarboxylic acid derivative thereof includes one hydroxyl group and one carboxylic acid group in the molecule. Is not particularly limited, but aliphatic hydroxycarboxylic acids corresponding to the aliphatic hydroxycarboxylic acid units of the following general formula (III) are suitable. 4 lower alkyl esters or their intramolecular esters are preferred.

^{HO-R 3 -COOH ... (III} )
In general formula (III), R ³ is a divalent aliphatic hydrocarbon group, preferably a C 1-11 carbon atom, particularly preferably a C 1-6 divalent aliphatic hydrocarbon group. R ³ may be a cycloalkylene group, but is preferably a chain hydrocarbon group. The “chain” includes not only “linear” but also “branched”.

  (C) The bifunctional aliphatic hydroxycarboxylic acid and / or derivative thereof is more preferably one in which a hydroxyl group and a carboxyl group are bonded to one carbon atom and represented by the following general formula (IV) Is preferred. The use of a bifunctional aliphatic hydroxycarboxylic acid represented by the following general formula (IV) or a derivative thereof is particularly preferable because the polymerization rate increases.

(In general formula (IV), a is 0 or an integer of 1 or more, preferably 0 or 1 to 10, more preferably 0 or an integer of 1 to 5.)
Specific examples of the bifunctional aliphatic hydroxycarboxylic acid include lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2- Examples include those obtained by ring-opening lactones such as hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, or caprolactone. These may be used alone or as a mixture of two or more. In addition, when an optical isomer exists in these, any of D-form, L-form, or a racemic form may be sufficient, and a solid, liquid, or aqueous solution may be sufficient as a shape. In particular, lactic acid and an aqueous solution thereof are particularly preferable since the increase in the polymerization rate during use is particularly remarkable and is easily available. Lactic acid is generally commercially available in 50%, 70%, and 90% aqueous solutions, and is easily available. Moreover, since the compatibility between the aliphatic polyester and polylactic acid is enhanced by using lactic acid, the use of lactic acid is preferred when the aliphatic polyester and polylactic acid are used in combination as a resin.

  The number average molecular weight Mn of the aliphatic polyester used in the present invention is generally 10,000 to 300,000, and usually 30,000 to 300,000.

  The resin molded body of the present invention is a resin molded body formed by molding a kneaded product containing microfibrillated cellulose and a resin, and the content of the microfibrillated cellulose is 4 to 15% by weight of the entire molded body. The relative strength compared with the strength of the molded body molded by the same method except that the strength of the molded body does not contain microfibrillated cellulose is 1.10 or more. The strength refers to tensile strength and bending strength. The relative strength is the strength of a molded body containing microfibrillated cellulose, and the strength of the molded body molded by the same method as the molded body of the present invention is 1 except that it does not contain microfibrillated cellulose. It is the strength when doing. Therefore, the relative strength of 1.10 is 1.10 times the strength of the molded body formed by the same method except that the strength of the molded body containing microfibrillated cellulose does not include microfibrillated cellulose. Say something. In the present invention, this relative strength is 1.10 or more, preferably 1.15 or more, more preferably 1.20 or more, and still more preferably 1.30 or more. Since a higher relative strength is preferable, an upper limit is not particularly required, but it is usually 1.60 or less, preferably 1.50 or less, more preferably 1.40 or less.

  The strength can be measured by the same method as in Test Example 1 described later.

  Further, in the resin molded body of the present invention, the content of microfibrillated cellulose is important, and in the test examples described later, the strength was maximum when this content was around 10% by weight of the entire molded body. When this content is less than 4% by weight or greater than 15% by weight, the relative strength becomes approximately 1 or less, and the improvement in strength is hardly observed or decreased despite the incorporation of microfibrillated cellulose. The preferred content of microfibrillated cellulose in the entire molded body is 5 to 15% by weight, more preferably 5 to 13% by weight, still more preferably 6 to 12% by weight, and even more preferably 6 to 11% by weight. It is.

  The resin molded body of the present invention can be produced by the method for producing a microfibrillated cellulose-containing resin molded body of the present invention. The method for producing a microfibrillated cellulose-containing resin molded article of the present invention is characterized in that when the microfibrillated cellulose and the resin are mixed, the microfibrillated cellulose is in a dispersed state and the resin is in a dissolved state. For example, it is possible to prepare a microfibrillated cellulose dispersion and a resin solution separately, and to mix both solutions, or to disperse the microfibrillated cellulose and dissolve the resin. It can also be set as the process of putting and mixing microfibrillated cellulose and resin in the solvent provided with. The former manufacturing method including the mixing step may be referred to as “two-component manufacturing method”, and the latter manufacturing method including the mixing step may be referred to as “one-component manufacturing method”. In addition, let the manufacturing method which has the process of preparing a microfibril cellulose dispersion liquid and a resin solution separately using the solvent provided with both properties, and mixing both liquids to be a 2 liquid type manufacturing method.

  Further, the property of dispersing microfibrillated cellulose may be referred to as “microfibrillated cellulose dispersibility”, the property of dissolving a resin as “resin solubility”, and both properties may be referred to as “dispersion solubility”.

  The one-component production method includes a step of dispersing the microfibrillated cellulose and dissolving the resin in a solvent having microfibrillated cellulose dispersibility and resin solubility, mixing the mixture, and then removing the solvent. And For example, microfibrillated cellulose is dispersed and stirred in acetone, then amorphous polylactic acid is dissolved and stirred and mixed, and then the solvent is removed to produce a resin in which microfibrillated cellulose is dispersed. In the one-component production method, the order of dispersion of the microfibrillated cellulose and dissolution of the resin is not particularly limited. Unlike the above example, the resin is dissolved in acetone and stirred, and then the microfibrillated cellulose is dispersed and stirred. The resin and the microfibrillated cellulose may be simultaneously mixed in acetone and mixed with stirring. The preferred order is the order in which the resin is dissolved after the microfibrillated cellulose is dispersed.

  The two-component production method is characterized by having a step of removing the solvent after mixing the solvent in which the resin is dissolved and the solvent in which the microfibrillated cellulose is dispersed. For example, prepare a solution in which microfibrillated cellulose is dispersed in acetone and a solution in which crystalline polylactic acid is dissolved in dichloromethane, then mix and stir the two solutions, then remove the solvent and microfibrillate. A resin in which cellulose is dispersed is produced. Therefore, considering the mixing of the microfibrillated cellulose and the resin, it is preferable that the microfibrillated cellulose dispersible solvent and the resin-soluble solvent are compatible with each other.

  Hereinafter, items common to the one-component manufacturing method and the two-component manufacturing method will be described. In the method for producing a microfibrillated cellulose-containing resin molded product, the amount of microfibrillated cellulose used is 4 to 15% by weight, preferably 5 to 15% by weight of the microfibrillated cellulose in the microfibrillated cellulose-containing resin molded product. %, More preferably 5 to 13% by weight, even more preferably 6 to 12% by weight, and even more preferably 6 to 11% by weight. The amount of resin used may be the remaining amount obtained by removing the microfibrillated cellulose from the molded body, or when other additives are used, it may be the remaining amount obtained by removing the microfibrillated cellulose and the additive from the molded body. . Further, the use weight of the microfibrillated cellulose relative to the use weight of the resin is preferably 5 to 15% by weight, more preferably 5 to 13% by weight, and still more preferably 6 to 12% by weight. When it exists in said range, the molded article obtained will become the thing excellent in intensity | strength.

  The solvent having decomposition solubility varies depending on the resin to be used, and is, for example, acetone, dichloromethane, cyclohexane, chloroform, ethyl acetate, etc., preferably acetone, dichloromethane, cyclohexane, more preferably acetone, dichloromethane. The solvent having decomposition solubility can be used as a solvent having microfibrillated cellulose dispersibility and a solvent having resin solubility.

  The solvent having microfibrillated cellulose dispersibility is, for example, methanol, ethanol, butanol or the like in addition to the above-mentioned dispersion-soluble solvent. Preferably, in addition to the dispersion-soluble solvent, methanol and ethanol are used, and methanol is more preferable.

  A solvent having resin solubility may be appropriately selected according to the resin to be used, and a solvent known as resin solubility can be used in addition to the above-mentioned dispersion-soluble solvent.

  In particular, when amorphous polylactic acid is used as the resin, acetone and dichloromethane are preferred as the dispersion-soluble solvent, acetone is preferred as the microfibrillated cellulose dispersion solvent, and amorphous such as dichloromethane as the resin-soluble solvent. Solvents having soluble polylactic acid solubility are preferred. When crystalline polylactic acid is used as the resin, acetone is preferable as the microfibrillated cellulose dispersible solvent, and a solvent having crystalline polylactic acid solubility of dichloromethane is preferable as the resin-soluble solvent.

  Each solvent can be used in combination of two or more as long as it has the same dispersibility and solubility. The amount of the solvent used may be appropriately set in consideration of dispersion of the microfibrillated cellulose, dissolution of the resin, mixing of the microfibrillated cellulose and the resin, removal of the solvent, and the like. In addition, when using 2 or more types of solvent in a mixing process, it is desirable from a viewpoint of the uniformity of mixing that a solvent is mutually compatible.

  The above solvent is used to mix until the microfibrillated cellulose is uniformly dispersed in the resin. The mixing temperature is usually 0 to 40 ° C., preferably 0 to 30 ° C., and the mixing time is usually 1 minute to 24 hours, preferably Is 3 minutes to 12 hours.

  The solvent is removed from the mixed solution prepared in the mixing step in the solvent removing step. The removal of the solvent is preferably performed under reduced pressure conditions in consideration of its efficiency. The solvent removal temperature can be appropriately selected in consideration of the boiling point of the solvent, reduced pressure conditions, and the like. In the solvent removal step, it is preferable to finish the step in as short a time as possible considering that the microfibrillated cellulose is slightly settled due to the above-described density difference. For this reason, the method of spreading a liquid mixture thinly and widely and removing a solvent in a short time is advantageous. Moreover, when there is little solvent amount, since a liquid mixture becomes a gel form and it becomes difficult to produce the density nonuniformity after stirring, it is preferable.

  When the solvent is removed in the solvent removal step, a solid resin in which microfibrillated cellulose is dispersed is obtained. Although it is possible to use this mixture as a molding material without kneading, the elastic modulus and strength of the molded product obtained by using the kneaded material obtained by kneading as the molding material are high. For the kneading step, a method used in the field of kneading a resin can be used. For example, a uniaxial, biaxial or multiaxial kneader, mixing roll, kneader, roll mill, Banbury mixer, screw press, disperser, etc. can be used. Although the kneading temperature varies depending on the resin, it is not lower than the glass transition point and not higher than the melting point of the resin, and is usually 80 to 220 ° C., preferably 100 to 200 ° C. It is.

  The kneaded product obtained by kneading is a resin in which microfibrillated cellulose is dispersed. This resin is excellent in moldability despite containing microfibrillated cellulose. By molding this resin, it is possible to obtain a resin molded body having a strength higher than that of the original resin. As the molding method used in this molding step, a known resin molding method can be applied. The molding conditions can be appropriately set by those skilled in the art. As described above, the strength of the original resin is enhanced in the molded body produced by this molding process. For this reason, it can be used not only for applications where the resin has been used, but also for applications where use has been postponed due to insufficient strength of the resin. The molded body of the present invention includes, for example, interior materials, exterior materials, structural materials, etc. of transportation equipment such as automobiles, trains, ships, airplanes, etc .; Parts, etc .: Mobile communication equipment such as mobile phones, structural materials, internal parts, etc .; Portable music playback equipment, video playback equipment, printing equipment, copying equipment, sports equipment, etc., structural materials, internal parts, etc .; Materials: Can be used as office equipment such as stationery.

  In the present invention, since the moldability is improved by adding a plasticizer, it is preferable to add a plasticizer. The plasticizer may be added at any time as long as the plasticizer can be uniformly mixed with the resin, but is preferably added to the microfibrillated cellulose dispersion or resin solution or kneaded. Moreover, the preferable addition amount of a plasticizer is 0.1 to 10 weight% with respect to the resin use weight. As the plasticizer, those generally used in the field of resins can be used. For example, di (2-ethylhexyl) phthalate, phthalate such as dibutyl phthalate and dinonyl phthalate, adipate such as di (2-ethylhexyl) adipate and dibutyl adipate, di (2-ethylhexyl) sebacate , Sebacic acid esters such as dibutyl sebacate, citrate esters such as tributyl acetylcitrate and triethyl citrate, phosphate plasticizers such as triphenyl phosphate and tricresyl phosphate, fatty acid plasticizers such as diethylene glycol monolate, Epoxy derivatives such as epoxidized soybean oil can be used. A biodegradable plasticizer is preferred.

  In the present invention, in addition to plasticizers, additives that are used in the field of resins such as antioxidants, colorants, UV absorbers, lubricants, flame retardants, foaming agents, fillers, etc. are widely used. can do.

  Conventionally, a resin containing microfibrillated cellulose deteriorates the molding processability of the original resin, and the strength of the molded body does not greatly exceed the original molded body of the resin. However, according to the method for producing a microfibrillated cellulose-containing resin of the present invention, a resin excellent in molding processability can be obtained despite containing the microfibrillated cellulose. It has an elastic modulus and strength superior to those of the resin molded product.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention in detail, this invention is not limited to these.

Example 1
Microfibrillated cellulose (hereinafter sometimes referred to as MFC): Serisch KY100G (manufactured by Daicel Chemical Industries)
-Bleached softwood kraft pulp: NBKP
Amorphous polylactic acid: LACEA H-280 (Mitsui Chemicals, Tg 56 ° C)
<Dispersion and mixing of MFC and amorphous polylactic acid (one-component production method)>
1% by weight of MFC was added to 500 g of acetone and stirred until it was uniformly dispersed. To this, 95 g of amorphous polylactic acid was added and stirred sufficiently until the polylactic acid dissolved and became a uniform gel. Subsequently, acetone was removed under reduced pressure at 70 ° C. to obtain a mixture containing 5% by weight of MFC.

  The obtained MFC-dispersed polylactic acid was put into a kneader (Brabender, Labo Plastmill, manufactured by Toyo Seiki Co., Ltd.) and kneaded 500 times at 40 rpm and 140 ° C. for 12 minutes. An optical micrograph of the kneaded product is shown in FIG.

  The obtained kneaded material was molded into a sheet having a thickness of 0.3 mm using a spacer. That is, using a spacer, the kneaded material was first pressed at 160 ° C. at 0.5 MPa for 5 minutes, then pressed at 1 MPa for 5 minutes, and then heat-treated at 90 ° C. for 1 hour to prepare a sheet. . The obtained sheet was cut into a size of 5 mm × 40 mm × 0.3 mm to obtain a sample.

Comparative Example 1 (melt kneading)
Prepare 300 g of dispersed water with 1% by weight of MFC added to water, add this dispersed water at 57 ° C. to 57 g of amorphous polylactic acid melted in a kneader, and knead and mold under the same conditions as in Example 1. And made a sample. An optical micrograph of the kneaded product is shown in FIG.

Comparative Example 2 (Amorphous polylactic acid)
A sample was prepared by kneading and molding 60 g of polylactic acid melted in a kneader under the same conditions as in Example 1.

Test example 1
The Young's modulus and tensile strength of the samples prepared in Examples and Comparative Examples were measured. A universal testing machine (Instron 3365, manufactured by Instron) was used for the measurement. The margin of the sample was 10 mm on each side, and the gap between the grips was about 20 mm. The number of samples was 6 in each test. The tensile speed was 1 mm / min and the measurement temperature was 20 ° C. The results are shown in FIG.

  The molded body of Example 1 has a greater improvement in both tensile strength and Young's modulus than polylactic acid, which is the original resin. In contrast, the molded article of Comparative Example 1 in which microfibrillated cellulose was mixed by melt kneading had an elastic modulus improved by about 10% compared to the original resin polylactic acid, but the strength was reduced by more than 10%. . In addition, as shown in FIG. 1, aggregates are observed in the kneaded material of Comparative Example 1, whereas aggregates are not recognized in the kneaded material of Example 1, and are neatly dispersed. It can be seen that the strength is reduced due to the agglomerates serving as the base point of the above. In contrast, in the dispersion kneading method, it can be seen that the microfibrillated cellulose is finely dispersed and contributes to the improvement of the strength.

Test example 2
Samples were prepared in the same manner as in Example 1, except that the amount of MFC added to the amorphous polylactic acid was 3 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt%. Using the obtained sample and the sample of Comparative Example 2, Young's modulus and tensile strength were measured in the same manner as in Test Example 1. The results are shown in FIG.

Example 2
・ MFC: Serisch KY100G (manufactured by Daicel Chemical Industries)
-Bleached softwood kraft pulp: NBKP (manufactured by Daishowa Paper Co., Ltd.)
Crystalline polylactic acid: LACEA H-100 (Mitsui Chemicals, Tg 60 ° C.)

<Dispersion mixing of MFC and crystalline polylactic acid (two-component manufacturing method)>
MFC was immersed in acetone, and water contained in MFC was replaced with acetone. Then, MFC was collected by filtration, and further immersed in dichloromethane to replace acetone with dichloromethane. 1% by weight of this MFC was added to 300 g of dichloromethane and stirred until it was uniformly dispersed. On the other hand, 57 g of crystalline polylactic acid was added to 200 g of dichloromethane, and the mixture was sufficiently stirred until the polylactic acid dissolved and became a uniform gel. Next, a mixture of MFC dispersed in dichloromethane and a solution of crystalline polylactic acid dissolved in dichloromethane were mixed and sufficiently stirred, and then dichloromethane was removed under reduced pressure at 60 ° C. to obtain a mixture containing 5% by weight of MFC. It was.

  The obtained MFC-dispersed polylactic acid was put into a kneader (Brabender, Labo Plastmill, manufactured by Toyo Seiki Co., Ltd.) and kneaded 500 times at 50 rpm and 160 ° C. for 10 minutes. The obtained kneaded material was molded into a sheet having a thickness of 0.3 mm using a spacer. That is, using a spacer, the kneaded material was first pressed at 190 ° C. at 0.5 MPa for 5 minutes, then pressed at 1 MPa for 5 minutes, and then heat-treated at 100 ° C. for 1 hour to prepare a sheet. . The obtained sheet was cut into a size of 5 mm × 40 mm × 0.3 mm to obtain a sample.

Comparative Example 3 (Crystalline polylactic acid)
A sample was prepared by kneading and molding molten crystalline polylactic acid under the same conditions as in Comparative Example 2.

Test example 3
The Young's modulus and tensile strength of the samples prepared in Example 2 and Comparative Example 3 were measured. A universal testing machine (Instron 3365, manufactured by Instron) was used for the measurement. The margin of the sample was 10 mm on each side, and the gap between the grips was about 20 mm. The number of samples was 6 in each test. The tensile speed was 1 mm / min and the measurement temperature was 20 ° C. The results are shown in Table 3. The molded product of Example 2 is improved in both tensile strength and Young's modulus compared to the original resin, polylactic acid.

  The microfibrillated cellulose-containing resin molded product of the present invention is excellent in strength. The microfibrillated cellulose-containing resin of the present invention is excellent in processability. The method for producing a microfibrillated cellulose-containing resin of the present invention is excellent in dispersibility of microfibrillated cellulose, the resin obtained by the production method is excellent in processability, and the molded article of the resin is excellent in strength.

The optical microscope photograph of the kneaded material of Example 1 and Comparative Example 1 is shown. The upper row is a photograph of the kneaded material of Example 1, and the lower row is a photograph of the kneaded material of Comparative Example 1. In the kneaded material of Comparative Example 1, aggregates (darker portions) were observed, whereas in the kneaded material of Example 1, no aggregates were observed and the particles were neatly dispersed. 6 is a graph showing the results of Test Example 1. The vertical axis represents stress (MPa), and the horizontal axis represents strain. 10 is a graph showing the results of Test Example 2. The vertical axis represents stress (MPa), and the horizontal axis represents strain. The 20% graph has almost the same slope as the 5% graft and overlaps with the 5% graft.

Claims (11)

A resin molded body obtained by molding a kneaded product containing microfibrillated cellulose and a resin,
The content of microfibrillated cellulose is 4 to 15% by weight of the whole molded body,
A resin molded body having a relative strength of 1.10 or more compared to the strength of a molded body molded by the same method except that the strength of the molded body does not include microfibrillated cellulose. The resin molded body according to claim 1, wherein the content of microfibrillated cellulose is 5 to 15% by weight of the entire molded body. The resin molding according to claim 1 or 2, wherein the relative strength is 1.15 or more. The resin molded body according to any one of claims 1 to 3, wherein the resin is at least one selected from the group consisting of biodegradable resins and aliphatic polyesters. Containing microfibrillated cellulose, comprising the steps of dispersing microfibrillated cellulose and dissolving resin in a solvent having microfibrillated cellulose dispersibility and resin solubility, mixing, and then removing the solvent. Manufacturing method of resin molding. The method for producing a microfibrillated cellulose-containing resin according to claim 5, wherein the solvent is acetone. A method for producing a microfibrillated cellulose-containing resin molded article, comprising: mixing a solvent in which a resin is dissolved and a solvent in which microfibrillated cellulose is dispersed, and then removing the solvent. The production method according to claim 7, wherein the solvent in which the resin is dissolved is dichloromethane, and the solvent in which the microfibrillated cellulose is dispersed is acetone. The production method according to any one of claims 5 to 8, wherein the content of the microfibrillated cellulose in the microfibrillated cellulose-containing resin molded product is 4 to 15% by weight. The production method according to claim 5, wherein the resin is at least one selected from the group consisting of biodegradable resins and aliphatic polyesters. The microfibrillated cellulose containing resin molding manufactured by the method in any one of Claims 5-10.

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