JP2010126637A - Molding material, molded article, casing for use in electronic appliance, and method for manufacturing molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding material which is high in the heat deformation temperature, is excellent in physical properties such as elastic modulus, and does not easily discolored during molding. <P>SOLUTION: This molding material comprises a composition including (1) a thermoplastic cellulose derivative and (2) a crystalline cellulose which has a purity of at least 90% or more and which is chemically modified. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a molding material, a molded body, a casing for electronic equipment, and a method for manufacturing the molded body.

  Various materials are used for members constituting electronic devices such as copiers and printers in consideration of characteristics and functions required for the members. For example, PC (Polycarbonate), ABS (Acrylonitrile-butadiene-styrene) resin, PC / ABS, etc. are generally used as a member (housing) that stores a drive machine of an electronic device and plays a role in protecting the drive machine. It is used in large quantities (Patent Document 1). These resins are produced by reacting compounds obtained from petroleum as a raw material.

  By the way, fossil resources such as oil, coal, and natural gas are mainly composed of carbon that has been fixed in the ground for many years. When such fossil resources or products made from fossil resources are burned and carbon dioxide is released into the atmosphere, carbon that was originally not deep in the atmosphere but fixed deep in the ground Is rapidly released as carbon dioxide, and the amount of carbon dioxide in the atmosphere greatly increases, which is considered to be one of the causes of global warming. Therefore, polymers such as ABS and PC made from petroleum, which is a fossil resource, have excellent characteristics as materials for components for electronic equipment, but are made from petroleum, which is a fossil resource. Therefore, from the viewpoint of preventing global warming, it is desirable to reduce the amount used.

On the other hand, a plant-derived resin is originally produced by a photosynthesis reaction using carbon dioxide and water in the atmosphere as raw materials. Therefore, even if plant-derived resin is incinerated to generate carbon dioxide, the carbon dioxide is equivalent to carbon dioxide originally in the atmosphere, so the balance of carbon dioxide in the atmosphere is plus or minus zero After all, there is an idea that the total amount of CO _{2 in} the atmosphere is not increased. Based on this idea, plant-derived resins are referred to as so-called “carbon neutral” materials. The use of carbon-neutral materials in place of petroleum-derived resins is an urgent need to prevent global warming in recent years.

  For this reason, in PC polymer, the method of reducing petroleum origin resources is proposed by using plant origin resources, such as starch, as some raw materials derived from petroleum (patent documents 2). However, further improvements are required from the perspective of aiming for a more complete carbon neutral material.

  Patent Documents 3 and 4 disclose molded parts reinforced with natural fibers using a cellulose derivative in a continuous phase (matrix).

JP-A-56-55425 JP 2008-24919 A Japanese Patent No. 3336493 Japanese National Patent Publication No. 9-500923

  However, in Patent Documents 3 and 4, although the strength is improved, the cellulose resin is colored (particularly dark brown) when heated at the stage of molding or the like. As a result, there is a problem that the molded product is colored.

  An object of the present invention is to provide a molding material having a high thermal deformation temperature, good physical properties such as an elastic modulus, and less coloration during molding, a molded body using the molding material, a casing for electronic equipment, and a molded body. It is to provide a manufacturing method.

As a result of intensive studies, the present inventor has solved the above problems by the following means.
1. A molding material comprising a composition comprising (1) a thermoplastic cellulose derivative and (2) crystalline cellulose having a purity of at least 90% and chemically modified.
2. 2. The molding material according to 1 above, wherein the crystalline cellulose is chemically modified with at least one organic group selected from the group consisting of an ester group, a carbonate group, an ether group and a carbamate group.
3. 3. The molding material as described in 2 above, wherein the crystalline cellulose is chemically modified with an aliphatic ester group.
4). 4. The molding material according to any one of 1 to 3, wherein the crystalline cellulose has an average minor axis length of 200 μm or less.
5). 5. The molding material according to any one of 1 to 4, wherein the crystallinity of the crystalline cellulose is 30% to 90%.
6). The molding material according to any one of 1 to 5, wherein the crystalline cellulose has an average major axis length of 0.3 mm to 10 mm.
7). The molded object obtained by shape | molding the molding material in any one of said 1-6.
8). A housing for an electronic device comprising the molded body as described in 7 above.
9. A method for producing a molded product containing cellulose, comprising mixing at least (1) a thermoplastic cellulose derivative and (2) crystalline cellulose having a purity of at least 90% and chemically modified. The manufacturing method of a molded object provided with the 1st process of obtaining a composition, and the 2nd process of heat-molding this composition.

  According to the present invention, it is possible to provide a molding material having a high heat distortion temperature, good physical properties such as elastic modulus, and hardly causing coloring during molding. Moreover, since the molded object formed with the molding material of this invention has said outstanding physical property, it can be used conveniently as a housing for electronic devices, for example. Moreover, since it is a plant-derived resin, it can be replaced with a conventional petroleum-derived resin as a material that can contribute to the prevention of global warming.

Hereinafter, the present invention will be described in detail.
(Thermoplastic cellulose derivative)
The cellulose derivative used in the present invention is not particularly limited as long as it exhibits thermoplasticity. Examples thereof include cellulose esters such as cellulose acetate propionate, cellulose acetate butyrate, and cellulose phthalate; cellulose ethers such as ethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

As the cellulose derivative of the present invention, at least a part of the hydrogen atoms of the hydroxyl group contained in cellulose ((C ₆ H ₁₀ O ₅ ) _n ) is a hydrocarbon group having 1 to 7 carbon atoms and an aliphatic group having 2 to 11 carbon atoms. A cellulose derivative substituted with an acyl group, that is, one having a polymer unit represented by the following general formula (1) can also be used.

In the above formula, R ² , R ³ and R ⁶ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 7 carbon atoms, or an aliphatic acyl group having 2 to 11 carbon atoms. However, at least one of R ² , R ³ , and R ⁶ is a hydrocarbon group having 1 to 7 carbon atoms or an aliphatic acyl group having 2 to 11 carbon atoms.

  The cellulose derivative having a polymer unit represented by the general formula (1) has thermoplasticity because at least part of the hydroxyl group of the β-glucose ring is etherified and esterified with a hydrocarbon group having a specific carbon number. It can be expressed and is suitable for molding. Moreover, the said cellulose derivative can express high heat deformation temperature also as a molded object. Furthermore, since cellulose is a complete plant-derived component, it is carbon neutral and can greatly reduce the burden on the environment.

The “cellulose” referred to in the present invention is a polymer compound in which a large number of glucoses are polymerized by β-1,4-glycosidic bonds, and the carbon atoms at the 2nd, 3rd and 6th positions in the glucose ring of cellulose. Means that the hydroxyl group bonded to is unsubstituted.
Further, “hydroxyl group contained in cellulose” refers to a hydroxyl group bonded to carbon atoms at the 2nd, 3rd and 6th positions in the glucose ring of cellulose.

The cellulose derivative having a polymer unit represented by the general formula (1) may be any part of the whole as long as it contains the hydrocarbon group and aliphatic acyl group having the specific carbon number, and consists of the same polymer unit. It may be a thing and may consist of a plurality of types of polymerized units. Further, it is not necessary to contain both the hydrocarbon group and the aliphatic alkyl group in one polymerization unit.
For example, (1) a monomer in which a part of R ² , R ³ and R ⁶ is substituted with a hydrocarbon group, and a part of R ² , R ³ and R ⁶ are substituted with an aliphatic acyl group (2) a single polymer unit in which R ² , R ³ and R ⁶ are both substituted with a hydrocarbon group and an aliphatic acyl group. A polymer composed of one monomer may be used. Further, (3) a polymer in which different types of polymer units represented by the general formula (1) are randomly polymerized may be used.
In addition, a part of the polymer may contain an unsubstituted polymer unit (that is, a polymer unit in which R ² , R ^3, and R ⁶ are all hydrogen atoms in the general formula (1)).

The hydrocarbon group having 1 to 7 carbon atoms may be either an aliphatic group or an aromatic group. In the case of an aliphatic group, it may be linear, branched or cyclic, and may have an unsaturated bond. Preferably it is a C1-C4 aliphatic group.
Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group, and an octyl group. A methyl group or an ethyl group is preferable, and a methyl group is more preferable. These may be used alone or in a combination of two or more.

The aliphatic acyl group having 2 to 11 carbon atoms preferably has 4 to 9 carbon atoms, and more preferably 7 to 9 carbon atoms.
Specifically, butyryl group, isobutyryl group, pentanoyl group, 2-methylbutanoyl group, 3-methylbutanoyl group, pivaloyl group, hexanoyl group, 2-methylpentanoyl group, 3-methylpentanoyl group, 4- Methylpentanoyl group, 2,2-dimethylbutanoyl group, 2,3-dimethylbutanoyl group, 3,3-dimethylbutanoyl group, 2-ethylbutanoyl group, heptanoyl group, 2-methylhexanoyl group, 3 -Methylhexanoyl group, 4-methylhexanoyl group, 5-methylhexanoyl group, 2,2-dimethylpentanoyl group, 2,3-dimethylpentanoyl group, 3,3-dimethylpentanoyl group, 2-ethyl Pentanoyl group, cyclohexanoyl group, octanoyl group, 2-methylheptanoyl group, 3-methylheptanoyl group, 4-methyl Heptanoyl group, 5-methylheptanoyl group, 6-methylheptanoyl group, 2,2-dimethylhexanoyl group, 2,3-dimethylhexanoyl group, 3,3-dimethylhexanoyl group, 2-ethylhexanoyl group 2-propylpentanoyl group, nonanoyl group, 2-methyloctanoyl group, 3-methyloctanoyl group, 4-methyloctanoyl group, 5-methyloctanoyl group, 6-methyloctanoyl group, 2,2- Dimethylheptanoyl group, 2,3-dimethylheptanoyl group, 3,3-dimethylheptanoyl group, 2-ethylheptanoyl group, 2-propylhexanoyl group, 2-butylpentanoyl group, decanoyl group, 2-methylnonanoyl Group, 3-methylnonanoyl group, 4-methylnonanoyl group, 5-methylnonanoyl group, 6-methylnonanoyl group Group, 7-methylnonanoyl group, 2,2-dimethyloctanoyl group, 2,3-dimethyloctanoyl group, 3,3-dimethyloctanoyl group, 2-ethyloctanoyl group, 2-propylheptanoyl group, 2 -A butylhexanoyl group etc. are mentioned. These may be used alone or in a combination of two or more.

The aliphatic moiety of the aliphatic acyl group having 2 to 11 carbon atoms may have any of a straight chain structure, a branched structure, and a cyclic structure, but preferably has a branched structure, in particular, the α-position of the carbonyl group An aliphatic moiety having a branched structure is more preferred. Thereby, strength, such as impact resistance, can be improved.
As the aliphatic acyl group having a branched aliphatic moiety, a 2-propylpentanoyl group, a 2-ethylhexanoyl group, a 2-methylheptanoyl group, and the like are particularly preferable.

  The aliphatic acyl group may have a further substituent. Further substituents include, for example, a hydroxy group, a mercapto group, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), a cyano group, a sulfo group, a carboxyl group, a nitro group, a hydroxamic acid group, a sulfino group, A hydrazino group, an imino group, etc. are mentioned.

The substitution position of the hydrocarbon group and the aliphatic acyl group in the cellulose derivative, and the number (substitution degree) of the hydrocarbon group and the aliphatic acyl group per β-glucose ring unit are not particularly limited.
For example, the substitution degree DS _B of the hydrocarbon group (the number of hydrocarbon groups relative to the hydroxyl groups at the 2nd, 3rd and 6th positions of the β-glucose ring in the polymer unit) is usually about 1.0 or more, preferably 1. What is necessary is just about 5-2.5.
Substitution degree DS _C of aliphatic acyl group (number of aliphatic acyl groups relative to hydroxyl groups at positions 2, 3 and 6 of the cellulose structure of the β-glucose ring in the polymerization unit) is usually about 0.1 or more, preferably What is necessary is just to be about 0.3-1.5. By setting it as the substituent of such a range, heat resistance, brittleness, etc. can be improved.

Further, the number of unsubstituted hydroxyl groups present in the cellulose derivative of the present invention is not particularly limited.
The substitution degree DS _{A of} hydrogen atoms (ratio in which the hydroxyl groups at the 2-position, 3-position and 6-position in the polymerization unit are unsubstituted) is usually about 0.01 to 1.5, preferably about 0.2 to 1.2. And it is sufficient. The DS _A by 0.01 or more, it is possible to improve the fluidity of the molding material. Further, by setting the DS _A and 1.5 or less, or to improve the fluidity of the molding material, the foaming and the like due to water absorption of the molding material during acceleration and molding of the pyrolysis can or is suppressed.
Note that the sum of the degrees of substitution (DS _A + DS _B + DS _C ) is 3.

The molecular weight of the cellulose derivative of the present invention is preferably in the range of 5,000 to 1,000,000, more preferably in the range of 10,000 to 500,000, and most preferably in the range of 100,000 to 200,000. The mass average molecular weight (Mw) is preferably in the range of 7000 to 5000000, more preferably in the range of 15000 to 2500,000, and most preferably in the range of 300000 to 150,000. The molecular weight distribution (MWD) is preferably in the range of 1.1 to 5.0, and more preferably in the range of 1.5 to 3.5. By setting the average molecular weight within this range, it is possible to improve the moldability and mechanical strength of the molded body. Further, by making the molecular weight distribution different from this range, the moldability and the like can be improved.
In the present invention, the number average molecular weight (Mn), mass average molecular weight (Mw) and molecular weight distribution (MWD) can be measured using gel permeation chromatography (GPC). Specifically, tetrahydrofuran can be used as a solvent, polystyrene gel can be used, and the molecular weight can be obtained using a conversion molecular weight calibration curve obtained in advance from a constituent curve of standard monodisperse polystyrene.

The method for producing the cellulose derivative of the present invention is not particularly limited. For example, a cellulose derivative having a polymerization unit represented by the general formula (1) can be obtained by using cellulose as a raw material and etherifying and esterifying cellulose. The raw material for cellulose is not limited, and examples thereof include cotton, linter, and pulp.
For specific production conditions, for example, the method described in “Encyclopedia of Cellulose” pages 131 to 164 (Asakura Shoten, 2000) can be referred to.

(Crystalline cellulose)
The crystalline cellulose used in the present invention has a purity of at least 90% or more and is chemically modified. The present invention contains crystalline cellulose that combines such high purity and chemical modification in a cellulose derivative that is a matrix resin, while suppressing coloring of a molded body during heat molding and the like, and It is possible to increase the thermal deformation temperature of the molded body and improve physical properties such as elastic modulus.

The purity of the crystalline cellulose of the present invention is 90% or more, preferably 95 to 100%. In the present invention, purity is measured according to JIS P8101.
The crystalline cellulose of the present invention is preferably chemically modified with at least one organic group selected from the group consisting of ester groups, carbonate groups, ether groups and carbamate groups. These substitution degrees are not particularly limited, but may be, for example, about 0.3 to 1.0.

  Examples of the ester group include the structures exemplified below. “*” Is a site bonded to the carbon atom at the 2nd, 3rd or 6th position of the glucose ring of cellulose.

  Examples of the carbonate group include the structures exemplified below.

  Examples of the ether group include the structures exemplified below.

  Examples of the carbamate group include the structures exemplified below.

  In the present invention, the organic group is preferably modified with an ester group (carbonyloxy group), more preferably an aliphatic ester group. Among these, an aliphatic ester group having 2 to 8 carbon atoms, particularly an aliphatic ester group having 3 carbon atoms (propionyloxy group) is preferable.

  The crystalline cellulose preferably has a crystallinity of 30% to 90%, more preferably 50 to 90%. By setting it as this range, the reinforcement effect of the thermoplastic cellulose which is matrix resin can be expressed more suitably. The degree of crystallinity in the present invention is a value measured by the method described in Journal of the Textile Society of Japan, 46, 324, 1990.

The minor axis length of crystalline cellulose is not particularly limited, but the average minor axis length is preferably 200 μm or less. When the average minor axis length is 200 μm or less, the unevenness of the surface of the molded article is reduced, and the appearance, feel, etc. are good, which is preferable. A more preferable average minor axis length is 10 μm to 100 μm. In the present invention, the average minor axis length can be measured with an optical microscope.
The major axis length of crystalline cellulose is not particularly limited, but the average major axis length is preferably 0.3 mm to 10 mm. When the average major axis length is 0.3 mm or more, the reinforcing effect of the thermoplastic cellulose, which is the matrix resin, is more preferably exhibited, which is preferable. A more preferred average major axis length is 0.5 mm to 8 mm, and a particularly preferred average major axis length is 1.0 mm to 5 mm. The average minor axis length and the average major axis length can be obtained by measuring the minor axis length and the major axis length of each sample by observation with an optical microscope and calculating the average value of 50 samples.
A preferable distribution of each axial length has a length in the range of plus or minus 15% of the average value, and is preferably 50% or more of the whole.

The molding material of this invention consists of a composition containing a thermoplastic cellulose derivative and crystalline cellulose.
The crystalline cellulose is preferably blended in an amount of 5 to 150 parts by weight, more preferably 10 to 100 parts by weight, and more preferably 10 to 50 parts by weight based on 100 parts by weight of the thermoplastic cellulose derivative. Further preferred.

  The molding material of the present invention may contain various additives as necessary.

  The molding material of the present invention may contain a filler (reinforcing material). By containing the filler, the mechanical properties of the molded body formed of the molding material can be enhanced.

  A well-known thing can be used as a filler. The shape of the filler may be any of fibrous, plate-like, granular, powdery and the like.

  When the molding material contains a filler, the content is not particularly limited, but is usually about 30 parts by mass or less, preferably about 5 to 10 parts by mass with respect to 100 parts by mass of the cellulose derivative.

The molding material of the present invention may contain a flame retardant. Thereby, the flame retarding effect such as reduction or suppression of the burning rate can be improved.
The flame retardant is not particularly limited, and a conventional flame retardant can be used. For example, brominated flame retardants, chlorine-based flame retardants, phosphorus-containing flame retardants, silicon-containing flame retardants, nitrogen compound-based flame retardants, inorganic flame retardants and the like can be mentioned. Among these, hydrogen halides are not generated by thermal decomposition during compounding with resin or during molding, causing corrosion of processing machines and molds, and worsening the work environment. Phosphorus-containing flame retardants and silicon-containing flame retardants are preferred because they are less likely to adversely affect the environment through the generation of harmful substances such as dioxins when they are diffused or decomposed.

  The phosphorus-containing flame retardant is not particularly limited, and a commonly used one can be used. Examples thereof include organic phosphorus compounds such as phosphate esters, phosphate condensation esters, and polyphosphates.

  When the molding material of the present invention contains a flame retardant, the content is not limited, but is usually about 30 parts by mass or less, preferably about 2 to 10 parts by mass with respect to 100 parts by mass of the cellulose derivative. . By setting it as this range, impact resistance, brittleness, etc. can be improved, or generation | occurrence | production of pellet blocking can be suppressed.

The molding material of the present invention further improves various properties such as moldability and flame retardancy within the range not impairing the object of the present invention, in addition to the thermoplastic cellulose derivative, crystalline cellulose, filler and flame retardant. For this purpose, other components may be included.
Examples of other components include polymers other than the cellulose derivatives and crystalline cellulose, plasticizers, stabilizers (antioxidants, UV absorbers, etc.), mold release agents (fatty acids, fatty acid metal salts, oxyfatty acids, fatty acid esters). Aliphatic saponified ester, paraffin, low molecular weight polyolefin, fatty acid amide, alkylene bis fatty acid amide, aliphatic ketone, fatty acid lower alcohol ester, fatty acid polyhydric alcohol ester, fatty acid polyglycol ester, modified silicone) and the like. Furthermore, a coloring agent containing a dye or a pigment can be added.

  As the polymer other than the cellulose derivative and crystalline cellulose, any of a thermoplastic polymer and a thermosetting polymer can be used, but a thermoplastic polymer is preferable from the viewpoint of moldability. Specific examples of polymers other than cellulose derivatives include polyolefins such as low-density polyethylene, high-density polyethylene, and polypropylene, polyesters, polyamides, polystyrenes, polyacetals, polyurethanes, aromatic and aliphatic polyketones, polyphenylene sulfide, polyetheretherketone, polyimides , Thermoplastic starch resin, polystyrene, acrylic resin, AS resin, ABS resin, AES resin, ACS resin, AAS resin, polyvinyl chloride resin, polyvinylidene chloride, vinyl ester resin, polyurethane, MS resin, polycarbonate, polyarylate , Polysulfone, polyethersulfone, phenoxy resin, polyphenylene oxide, poly-4-methylpentene-1, polyetherimide, polyvinyl alcohol, Saturated polyester, melamine resins, phenol resins, and the like urea resins. In addition, ethylene-propylene copolymer, ethylene-propylene-nonconjugated diene copolymer, ethylene-butene-1 copolymer, various acrylic rubbers, ethylene-acrylic acid copolymers and alkali metal salts thereof (so-called ionomers), Ethylene-glycidyl (meth) acrylate copolymer, ethylene-alkyl acrylate copolymer (for example, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer), acid-modified ethylene-propylene copolymer , Diene rubber (eg, polybutadiene, polyisoprene, polychloroprene), copolymer of diene and vinyl monomer (eg, styrene-butadiene random copolymer, styrene-butadiene block copolymer, styrene-butadiene-styrene block) Copolymer, styrene Isoprene random copolymer, styrene-isoprene block copolymer, styrene-isoprene-styrene block copolymer, polybutadiene graft copolymerized with styrene, butadiene-acrylonitrile copolymer), polyisobutylene, isobutylene and butadiene or Examples include copolymers with isoprene, natural rubber, thiocol rubber, polysulfide rubber, acrylic rubber, polyurethane rubber, polyether rubber, and epichlorohydrin rubber.

  These polymers may be used alone or in combination of two or more.

  When the molding material of the present invention contains a polymer other than the thermoplastic cellulose derivative and crystalline cellulose, the content is preferably about 30 parts by mass or less, and about 2 to 10 parts by mass with respect to 100 parts by mass of the cellulose derivative. More preferred.

  The molding material of the present invention may contain a plasticizer. Thereby, a flame retardance and a moldability can be improved further. As the plasticizer, those commonly used for polymer molding can be used. Examples thereof include polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, polyalkylene glycol plasticizers, and epoxy plasticizers.

  When the molding material of this invention contains a plasticizer, about 1-30 mass parts is preferable with respect to 100 mass parts of cellulose derivatives, More preferably, it is about 5-20 mass parts.

Phenol radical scavengers and amine radical scavengers can be used as the antioxidant, but phenols are preferred from the viewpoint of coloring.
When the molding material of the present invention contains an antioxidant, the content thereof is preferably about 0.01 to 5 parts by mass, more preferably about 0.05 to 1 part by mass with respect to 100 parts by mass of the cellulose derivative. is there.

(Molded body)
The molded body of the present invention can be obtained by molding the molding material of the present invention. More specifically, it can be obtained by melting the molding material of the present invention by heating or the like and molding it by various molding methods.
Examples of the molding method include injection molding, extrusion molding, blow molding, and press molding.
The heating temperature is usually about 160 to 270 ° C, preferably about 180 to 250 ° C.

  The molding material of the present invention is excellent in physical properties such as elastic modulus and has a property that it is difficult to cause coloring during molding. Therefore, the molded article of the present invention can be suitably used as a casing for electronic devices such as a copying machine, a printer, a personal computer, and a television.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the scope of the present invention is not limited to the examples shown below.

[Preparation Example 1]
(Preparation of acicular cellulose crystals)
Microcrystalline cellulose (Asahi Kasei Chemicals, Theolas PH-102, average particle size 80 μm, cellulose purity 99%) was dispersed in distilled water at 2 mass%. This was subjected to counter collision treatment at 200 MPa for 30 times with a high-pressure homogenizer (manufactured by Sugino Machine Co., Ltd., Starburst Lab, HJP-25005) to obtain a needle-like cellulose crystal dispersion. The refined particles had an average minor axis length of 20 nm and an average major axis length of 500 nm. The dispersion was freeze-dried to obtain acicular cellulose crystal powder (C-1).

[Preparation Example 2]
To a 5 L three-necked flask was added 50 g of microcrystalline cellulose (CEOLATH PH-102, manufactured by Asahi Kasei Chemicals Corporation, average particle size 80 μm, cellulose purity 99%) and 2500 mL of dehydrated N, N-dimethylacetamide, and heated to 80 ° C. 100 mg of dimethylaminopyridine was added, and 148 mL of propionic anhydride was added. After reacting for 7 hours, after cooling to 30 ° C., 200 mL of methanol was added. The reaction solution was filtered, and the crystal separated by filtration was washed with methanol, filtered, and vacuum dried to obtain propionylated microcrystalline cellulose (C-2).

[Preparation Example 3]
In the same manner as in Preparation Example 2, (C-1) and ramie fibers (Toyobo, average length 5 mm, cellulose purity 95%) and kenaf fibers (Unipaax, average length 5 mm, cellulose purity 82%) Each propionyloxy group was modified by propionylation. As a result, propionylated acicular cellulose crystals (C-3), propionylated ramie fibers (C-4), and propionylated kenaf fibers (C-5) were obtained.
The crystallinity of (C-1) is 70%, the crystallinity of unmodified microcrystalline cellulose (Theolas PH102) is 75%, the crystallinity of (C-2) is 72%, (C-3) Has a crystallinity of 70%, an unmodified ramie fiber has a crystallinity of 78%, (C-4) has a crystallinity of 75%, an unmodified kenaf fiber has a crystallinity of 45%, (C-5) The crystallinity of was 40%.
In addition, the cellulose purity before and after modification by propionylation does not change.

[Preparation Example 4]
Disperse 20 g of (C-2) in 700 g of acetone, add 80 g of cellulose acetate propionate (manufactured by Eastman Chemical, CAP482-20, hereinafter referred to as CAP) and 0.5 g of Irganox 1010 (manufactured by Ciba Specialty Chemicals), CAP was dissolved by stirring at room temperature. This solution is put into a water / methanol 1/1 (volume ratio) mixed solution, filtered, and vacuum dried to obtain an 80/20 (mass ratio) mixture (M-1) of CAP and (C-2). It was.

[Preparation Example 5]
In the same manner as in Preparation Example 4, according to the blending ratio shown in Table 1 below, (C-3), (C-4), unmodified microcrystalline cellulose (Asahi Kasei Chemicals, Theolas PH-102, average particle size 80 μm, cellulose purity 99%), (C-1), unmodified ramie fibers (Toyobo, average length 5 mm, cellulose purity 95%), unmodified kenaf fibers (Unipax, average length 5 mm, cellulose purity) 82%), a mixture of each of (C-5) and CAP was prepared (M-2 to M-3, H-2 to H-6). Moreover, the mixture (H-1) of only CAP and Irganox 1010 was prepared.

(Preparation of test piece)
M-1, M-2, M-3, H-1 to H-6 obtained above are supplied to an injection molding machine (manufactured by Imoto Seisakusho Co., Ltd., semi-automatic injection molding machine), and the cylinder temperature is 220 to 250. A multi-purpose test piece of 4 × 10 × 80 mm was molded at a temperature of 30 ° C., a mold temperature of 30 ° C., and an injection pressure of 1.5 kgf / cm ² .

(Measurement of physical properties of specimen)
About the obtained test piece, coloring was observed visually and the heat deformation temperature (HDT) and the bending elastic modulus were measured according to the following method.

[Heat deformation temperature (HDT)]
In accordance with ISO75, a constant bending load (1.8 MPa) is applied to the center of the test piece (in the flatwise direction), the temperature is increased at a constant speed, and the temperature when the strain at the center reaches 0.34 mm is set. It was measured.

[Flexural modulus]
Based on ISO178, the bending elastic modulus was measured using an autograph manufactured by Shimadzu Corporation.
The results are summarized in Table 2.

  Since the molding material of the present invention is characterized by comprising a composition comprising a thermoplastic cellulose derivative and crystalline cellulose that is highly purified and chemically modified, the tea discoloration of the molded product is suppressed, In addition, the elastic modulus and the heat distortion temperature can be improved.

Claims (9)

  A molding material comprising a composition comprising (1) a thermoplastic cellulose derivative and (2) crystalline cellulose having a purity of at least 90% and chemically modified.   The molding material according to claim 1, wherein the crystalline cellulose is chemically modified with at least one organic group selected from the group consisting of an ester group, a carbonate group, an ether group and a carbamate group.   The molding material according to claim 2, wherein the crystalline cellulose is chemically modified with an aliphatic ester group.   The molding material in any one of Claims 1-3 whose average short-axis length of the said crystalline cellulose is 200 micrometers or less.   The molding material in any one of Claims 1-4 whose crystallinity degree of the said crystalline cellulose is 30%-90%.   The molding material in any one of Claims 1-5 whose average major axis length of the said crystalline cellulose is 0.3 mm-10 mm.   The molded object obtained by shape | molding the molding material in any one of Claims 1-6.   A housing for an electronic device comprising the molded body according to claim 7.   A method for producing a molded product containing cellulose, comprising mixing at least (1) a thermoplastic cellulose derivative and (2) crystalline cellulose having a purity of at least 90% and chemically modified. The manufacturing method of a molded object provided with the 1st process of obtaining a composition, and the 2nd process of heat-molding this composition.