JP5689375B2 - Polylactic acid resin composition - Google Patents

Description

  The present invention relates to a polylactic acid resin composition. More specifically, a polylactic acid resin composition that can be suitably used as household goods, home appliance parts, automobile parts, etc., a polylactic acid resin molded article obtained by molding the composition, and the polylactic acid resin molded article It relates to the manufacturing method.

  Polylactic acid resin is inexpensive because L-lactic acid as a raw material is produced by fermentation using sugars extracted from corn, straw, etc., and the total carbon oxide emissions are extremely high because the raw material is derived from plants. It is expected to be used at present because it is rare and the properties of the resin are high rigidity and high transparency.

  However, in addition to the above properties, polylactic acid resin is brittle and hard, so it has the property of lacking flexibility, so its use is limited, such as daily goods, home appliance parts, automobile parts, etc. There is almost no use record in the field. In addition, when molded into injection molded bodies, etc., there are problems such as insufficient mechanical strength such as flexibility and impact resistance, and problems such as whitening and inferior hinge characteristics when bent. The current situation is not.

  On the other hand, various proposals have been made as techniques for applying polylactic acid resin to the hard field.

  For example, in Patent Document 1, by adding cellulose having a crystallinity of less than 50% to a polylactic acid resin, a molded product obtained by molding the composition has both strength and flexibility. It is described that it can be applied to various uses such as household goods, home appliance parts, and automobile parts.

  Patent Document 2 discloses that a flame-retardant polylactic acid resin composition obtained by blending an organic phosphinic acid metal salt-based flame retardant can be used for a housing of an electrical product or the like. With respect to such a resin composition, it is disclosed that it is preferable to further blend a glass fiber for improving fastness and a rubber-based impact resistance improving agent for improving impact resistance.

  Moreover, in patent document 3, not only it has the heat resistance which was extremely superior to the conventional thing by mix | blending specific amount of a core shell polymer and a fiber with respect to the resin component which added polybutylene terephthalate to polylactic acid resin. In addition, it is disclosed that a polylactic acid-based composition satisfying molding processability and impact resistance can be obtained. As the core-shell polymer, a graft copolymer obtained by graft-polymerizing an aromatic vinyl compound and / or a (meth) acrylic acid ester compound as a shell component to a polymer or acrylic rubber particles containing a conjugated diene compound as a core component Are mentioned as preferred examples, and it is described that these contribute particularly to improvement of heat resistance. Preferable examples of the fiber include basalt fiber, bamboo fiber, kenaf fiber, carbon fiber, and glass fiber.

JP 2010-270289 A WO2009 / 130904 pamphlet JP 2007-246694 A

  In consideration of Patent Documents 1 to 3, an impact-absorbing agent may be further added to the polylactic acid resin in which cellulose having a crystallinity of less than 50% is added to increase flexibility. However, the applicant of the present application has found a problem that an injection molded resin composition is colored when an impact resistant absorbent is blended.

  An object of the present invention is to provide a polylactic acid resin composition having excellent strength and impact resistance and good color tone, a polylactic acid resin molded article obtained by molding the composition, and a method for producing the molded article There is to do.

  Therefore, as a result of repeated studies to solve the above problems, the present inventors have found that a specific amount of cellulose having a crystallinity of less than 50%, a specific amount of rubber component, and further a specific amount of polylactic acid resin. It has been found that a molded product obtained by blending glass fibers is excellent in all of strength, impact resistance and color tone, and has completed the present invention.

That is, the present invention
[1] A polylactic acid resin composition comprising a polylactic acid resin, cellulose having a crystallinity of less than 50%, glass fiber, and a rubber component, wherein the crystallinity is 100 parts by weight of the polylactic acid resin. A polylactic acid resin composition comprising less than 50% cellulose by 5 to 350 parts by weight, glass fiber by 1 to 25 parts by weight, and rubber component by 1 to 45 parts by weight,
[2] A polylactic acid resin molded article obtained by molding the polylactic acid resin composition according to [1], and [3] a melt kneader using the polylactic acid resin composition according to [1] above using a melt kneader. The present invention relates to a method for producing a polylactic acid resin molded body, which includes a step and a step of molding by an injection molding machine.

  The polylactic acid resin composition of the present invention is excellent in strength and impact resistance and has an excellent color tone. In addition, since cellulose, which is a biomass resource, is contained as a filler, it is possible to reduce costs and reduce total carbon oxide emissions.

  The polylactic acid resin composition of the present invention is a resin composition containing a polylactic acid resin, cellulose having a crystallinity of less than 50%, glass fibers, and a rubber component, and is based on 100 parts by weight of the polylactic acid resin. The main characteristics are that the cellulose having a crystallinity of less than 50% is 5 to 350 parts by weight, the glass fiber is 1 to 25 parts by weight, and the rubber component is 1 to 45 parts by weight.

  General cellulose has a crystallinity of about 80%. If necessary, the biodegradable resin composition can be used as a reinforcing material having biodegradability instead of an inorganic filler by further increasing the crystallinity. May be used for On the other hand, it is contrary to the technology that increases the crystallinity and enhances the strength, and by blending cellulose whose crystallinity is reduced to less than 50%, the cellulose plays a role as a plasticizer. It has become clear that it has become possible to achieve both flexibility and flexibility. Therefore, it is presumed that an impact resistant absorbent is further blended. However, when a resin composition containing a polylactic acid resin, cellulose having a crystallinity of less than 50%, and a rubber component as an impact absorbent is injection molded, the resulting molded product is colored and inferior in color tone The problem of becoming. Therefore, as a result of the study by the present inventors, surprisingly, by blending specific amounts of cellulose, glass fiber, and rubber components having a crystallinity of less than 50% with respect to the polylactic acid resin, the strength, It was found that both the impact resistance and the color tone were excellent. Although the detailed reason is unknown, when a rubber component is blended with polylactic acid resin and cellulose having a crystallinity of less than 50%, these components interact with each other due to shear heat generation during melt-kneading or injection molding. Coloring is thought to occur. However, it is considered that by blending glass fibers therein, the polylactic acid resin, cellulose, and rubber components are appropriately dispersed and aggregation is relaxed, thereby reducing the interaction and consequently suppressing the coloring. Moreover, it is thought that by suppressing aggregation, the effect inherent to the rubber component is easily exhibited, and the impact resistance is improved. In this specification, “strength” means a property evaluated by “flexural modulus” described later.

<Polylactic acid resin composition>
[Polylactic acid resin]
The polylactic acid resin is obtained by polycondensation of only a lactic acid component as a raw material monomer, and / or polylactic acid obtained by polycondensing them using a lactic acid component and a hydroxycarboxylic acid component as raw material monomers ( Copolymer).

  In lactic acid, there are optical isomers of L-lactic acid (L form) and D-lactic acid (D form). In the present invention, as the lactic acid component, either one or both of the optical isomers may be contained. However, from the viewpoint of improving moldability, lactic acid having a high optical purity mainly containing any one of the optical isomers. Is preferably used. In the present specification, the “main component” refers to a component whose content in the lactic acid component is 50 mol% or more.

  The content of the L-form or D-form in the lactic acid component, that is, the content of whichever one of the isomers is greater, in any case where only the lactic acid component or the lactic acid component and the hydroxycarboxylic acid component are polycondensed 80-100 mol% is preferable, 85-100 mol% is more preferable, 90-100 mol% is further more preferable, 98-100 mol% is further more preferable. In addition, since it is preferable that the total content of L-form and D-form in a lactic acid component is substantially 100 mol%, the content of the smaller one of the isomers is 0 to 20 mol% is preferable, 0-15 mol% is more preferable, 0-10 mol% is further more preferable, and 0-2 mol% is further more preferable.

  On the other hand, examples of the hydroxycarboxylic acid component include hydroxycarboxylic acid compounds such as glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, and hydroxyheptanoic acid, and are used alone or in combination of two or more. can do. Among these, glycolic acid and hydroxycaproic acid are preferable from the viewpoints of achieving both the strength and impact resistance of the polylactic acid resin composition and improving heat resistance and transparency.

  Moreover, in this invention, the dimer of the said lactic acid and the hydroxycarboxylic acid compound may be contained in each component. Examples of the lactic acid dimer include lactide, which is a cyclic dimer of lactic acid, and examples of the dimer of the hydroxycarboxylic acid compound include glycolide, which is a cyclic dimer of glycolic acid. The lactide includes L-lactide, which is a cyclic dimer of L-lactic acid, D-lactide, which is a cyclic dimer of D-lactic acid, meso-lactide obtained by cyclic dimerization of D-lactic acid and L-lactic acid, And DL-lactide, which is a racemic mixture of D-lactide and L-lactide, and any lactide can be used in the present invention, but both the strength and impact resistance of the polylactic acid resin composition are achieved, and heat resistance From the viewpoint of improving properties and transparency, D-lactide and L-lactide are preferable. The lactic acid dimer may be contained in any lactic acid component when the lactic acid component alone is polycondensed and when the lactic acid component and the hydroxycarboxylic acid component are polycondensed.

  The content of the lactic acid dimer is preferably 80 to 100 mol% and more preferably 90 to 100 mol% in the lactic acid component from the viewpoint of achieving both the strength and impact resistance of the polylactic acid resin composition.

  The content of the dimer of the hydroxycarboxylic acid compound is preferably 80 to 100 mol%, and preferably 90 to 100 mol% in the hydroxycarboxylic acid component from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition. More preferred.

  The condensation polymerization reaction of only the lactic acid component and the condensation polymerization reaction of the lactic acid component and the hydroxycarboxylic acid component are not particularly limited and can be performed using a known method.

  Thus, by selecting the raw material monomer, for example, from 80 to 100 mol% of either L-lactic acid (L-form) or D-lactic acid (D-form) unit and 0 to 20 mol% of the lactic acid unit of the enantiomer. Polylactic acid, or polylactic acid composed of 85 to 100 mol% of either L-lactic acid or D-lactic acid and 0 to 15 mol% of a hydroxycarboxylic acid unit. Among these, a cyclic dimer of lactic acid is used. Polylactic acid obtained by using a certain lactide, glycolide which is a cyclic dimer of glycolic acid, and caprolactone as raw material monomers is preferable.

  In the present invention, as polylactic acid, a lactic acid component mainly composed of different isomers is used from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and improving heat resistance and transparency. You may use the stereocomplex polylactic acid which consists of two types of obtained polylactic acid.

  One polylactic acid constituting the stereocomplex polylactic acid (hereinafter referred to as polylactic acid (A)) contains 90 to 100 mol% of L isomer and 0 to 10 mol% of other components including D isomer. The other polylactic acid (hereinafter referred to as polylactic acid (B)) contains 90 to 100 mol% of D isomer and 0 to 10 mol% of other components including L isomer. In addition, as other components other than L-form and D-form, dicarboxylic acid, polyhydric alcohol, hydroxycarboxylic acid, lactone, etc. having a functional group capable of forming two or more ester bonds are exemplified, and unreacted Polyester, polyether, polycarbonate or the like having two or more of the functional groups in the molecule may be used.

  In the stereocomplex polylactic acid, the weight ratio of polylactic acid (A) to polylactic acid (B) [polylactic acid (A) / polylactic acid (B)] is preferably 10/90 to 90/10, and 20/80 to 80 / 20 is more preferable, and 40/60 to 60/40 is more preferable.

  Furthermore, in the present invention, from the viewpoint of improving the impact resistance of the polylactic acid resin composition, it is preferable to use a polylactic acid resin obtained by crosslinking the polylactic acid resin with a crosslinking agent.

  A known crosslinking agent can be used as the crosslinking agent, but a polycarbodiimide-based crosslinking agent is preferable from the viewpoint of reactivity with the polylactic acid resin. Examples of the polycarbodiimide-based crosslinking agent include poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (diisopropylphenylcarbodiimide), poly (triisopropylphenylcarbodiimide), and the like. Aromatic polycarbodiimides; alicyclic polycarbodiimides such as poly (dicyclohexylmethanecarbodiimide), and aliphatic polycarbodiimides such as poly (diisopropylcarbodiimide). These polycarbodiimide-based crosslinking agents may be used alone or in combination of two or more. Can be used. Of these, aromatic polycarbodiimide and alicyclic polycarbodiimide are preferable, and at least one selected from poly (dicyclohexylmethanecarbodiimide) and poly (diisopropylphenylcarbodiimide) is more preferable. The amount of the crosslinking agent used is not particularly limited. For example, 0.1 to 5 parts by weight of the crosslinking agent can be used with respect to 100 parts by weight of the polylactic acid resin to be crosslinked.

  The crosslinking method is not particularly limited, and can be obtained, for example, by melt-kneading a polylactic acid resin and a crosslinking agent preferably at 190 to 220 ° C. The obtained pellets may be appropriately dried.

  The content of polylactic acid in the polylactic acid resin is preferably 80% by weight or more, more preferably 90% by weight or more, and further preferably substantially 100% by weight.

  In addition, although the polylactic acid resin can be synthesized by the above-described method, Laissia H-100 is a commercially available product from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and improving the heat resistance. H-280, H-400, H-440 (manufactured by Mitsui Chemicals), 3001D, 3051D, 4032D, 4042D, 6201D, 6251D, 7000D, 7032D (manufactured by Nature Works), eco-plastic U'z S-09, S -12, S-17 (manufactured by Toyota Motor Corporation) are preferred.

  Moreover, in this invention, other biodegradable resin other than the said polylactic acid resin may be contained suitably in the range which does not impair the effect of this invention. Examples of other biodegradable resins include polyester resins such as polybutylene succinate, polyhydroxyalkanoic acid, and the like. Moreover, the said polylactic acid resin may be contained as a polymer alloy by the blend of said other biodegradable resin and non-biodegradable resins, such as a polypropylene, and polylactic acid.

  The content of the polylactic acid resin is preferably 50% by weight or more from the viewpoint of achieving both the strength and impact resistance of the resin composition in the resin component contained in the composition and improving heat resistance and productivity. More preferably, it is more than 90% by weight.

[cellulose]
The cellulose used in the present invention is cellulose having a crystallinity of less than 50%.

In this specification, the crystallinity of cellulose is cellulose I-type crystallinity calculated by the Segal method from the diffraction intensity value by the X-ray diffraction method, and is defined by the following calculation formula (A).
Cellulose type I crystallinity (%) = [(I22.6-I18.5) /I22.6] × 100 (A)
[Wherein I22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and I18.5 is the amorphous portion (diffraction angle 2θ = 18.5 °). Shows the diffraction intensity of
Here, the cellulose I type crystallinity means the ratio of the crystal region amount to the whole cellulose. Therefore, it is understood that the cellulose having a cellulose I-type crystallinity of less than 50% is a cellulose having a crystal region amount of less than 50%, that is, a cellulose having an amorphous portion exceeding 50%. In the present specification, cellulose having an amorphous portion exceeding 50% is sometimes referred to as amorphous cellulose, and cellulose having a crystal region amount of 50% or more is sometimes referred to as crystalline cellulose. Cellulose type I is a crystalline form of natural cellulose. Cellulose type I crystallinity is also related to the physical and chemical properties of cellulose. The higher the value, the greater the hardness, density, etc. , Elongation, flexibility and chemical reactivity are reduced.

  The crystallinity of the cellulose used in the present invention is less than 50%, preferably 45% or less, more preferably 30% or less, and 20% from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition. The following is more preferable, and 10% or less is further preferable, and it is further preferable that the amount is substantially 0% in which no type I crystal is detected in the X-ray diffraction analysis. The cellulose I type crystallinity defined by the calculation formula (A) may be a negative value in calculation, but in the case of a negative value, the cellulose I type crystallinity is 0%. In the present invention, two or more kinds of celluloses having different crystallinity levels may be used in combination. In this case, the crystallinity degree of cellulose means the crystallinity degree obtained by the weighted average of the cellulose used. The value is preferably within the above range.

  Cellulose is not particularly limited as long as the degree of crystallinity is less than 50%. For example, cellulose is preferably obtained by subjecting a cellulose-containing raw material to mechanical treatment described later.

  The cellulose-containing raw material is not particularly limited, and plant parts such as trunks, branches, leaves, stems, roots, seeds and fruits, for example, plant stems and leaves such as rice straw and corn stalks; rice husks and palm husks Plant shells such as coconut shells can be used. Pulp such as thinned wood, pruned branches, various wood chips, wood pulp produced from wood, and cotton linter pulp obtained from fibers around cotton seeds; papers such as newspapers, cardboard, magazines, and fine paper However, from the viewpoint of obtaining a polylactic acid resin molded body with little coloring, pulp is preferable. Furthermore, recycled pulp or recycled paper obtained by regenerating paper (waste paper) such as newspaper, corrugated cardboard, magazine, and high-quality paper can also be used.

  Moreover, as a cellulose containing raw material, commercially available crystalline cellulose can also be used. Examples of commercially available crystalline cellulose include KC Flock (manufactured by Nippon Paper Chemicals Co., Ltd.), Theolas (manufactured by Asahi Kasei Chemicals Co., Ltd.), and the like.

  The form of these cellulose-containing raw materials is not particularly limited, and various forms such as chips and sheets can be used. The cellulose I type crystallinity of commercially available pulp is usually 80% or higher, and the cellulose I type crystallinity of commercially available crystalline cellulose is usually 80% or higher. The cellulose I-type crystallinity of the cellulose-containing raw material used in the present invention is preferably at least 50% or more.

  The cellulose-containing raw material preferably has a cellulose content in the remaining components when water is removed from the raw material, preferably 20% by weight or more, more preferably 40% by weight or more, and even more preferably 60% by weight or more. It is desirable. For example, in the commercially available pulp, the cellulose content in the remaining components when water is removed is usually 75 to 99% by weight, and other components include lignin and the like. In addition, there is no limitation in particular as a method of removing water from a raw material, For example, it can carry out by drying by vacuum drying or dry air. In the present specification, the cellulose content means the total amount of cellulose and hemicellulose, and the cellulose content can be measured by the method described in Examples described later.

  Moreover, when using pulp, recycled paper, etc. as a cellulose containing raw material, from the viewpoint of improving the impact resistance of the polylactic acid resin molded article, the amount of lignin in the cellulose containing raw material is preferably 15% by weight or less, more preferably Is 10% by weight or less, more preferably 8% by weight or less. The structural unit of lignin is not particularly limited and may be a known unit, but from the viewpoint of improving the impact resistance of the polylactic acid resin molded article, guaiacyl type, syringyl type, p-hydroxyphenyl It is desirable to be a mold.

  Examples of the method for reducing lignin include an alkali cooking method described in JP-A-2008-92910 and a sulfuric acid decomposition method described in JP-A-2005-229821.

  In addition, when using recycled pulp or recycled paper as the cellulose-containing raw material, from the viewpoint of achieving both the crystallinity of the polylactic acid resin and the strength and flexibility of the polylactic acid resin composition, the ash content of the cellulose-containing raw material is Preferably it is 35 weight% or less, More preferably, it is 20 weight% or less, More preferably, it is 10 weight% or less.

  The water content of the cellulose-containing raw material is preferably 20% by weight or less, more preferably 15% by weight or less, and further preferably 10% by weight or less. If the water content of the cellulose-containing raw material is 20% by weight or less, it can be easily pulverized and the crystallinity can be easily reduced by mechanical treatment. In addition, in this specification, the moisture content of a cellulose containing raw material can be measured by the method as described in the below-mentioned Example.

  The mechanical treatment is to pulverize the cellulose-containing raw material, and by this treatment, the crystallinity of cellulose can be reduced and the amorphous material can be efficiently made amorphous. From the viewpoint of efficiently reducing the degree of crystallinity, the cellulose-containing raw material whose bulk density and average particle diameter are adjusted may be subjected to pulverization treatment, and from the viewpoint of improving the durability of the polylactic acid resin molded body The cellulose-containing raw material whose water content is adjusted may be subjected to pulverization. Moreover, you may use for the grinding | pulverization process made to amorphize as it is, without adjusting a bulk density, an average particle diameter, and a water content.

(Method for preparing cellulose-containing raw material with adjusted bulk density and average particle size)
The method for adjusting the bulk density and the average particle size of the cellulose-containing raw material is not particularly limited. From the viewpoint of destroying the crystal structure of cellulose and pulverizing, for example, the compressive shear force described in JP 2010-270289 A A method of pulverizing by acting is preferable. In addition, after that, the cellulose-containing raw material or the water content obtained by the primary pulverization and the primary pulverization were adjusted in order to adjust the bulk density and the average particle size of the cellulose-containing raw material by applying a compressive shear force. The pulverization performed to amorphize the cellulose-containing raw material is sometimes referred to as secondary pulverization.

  Prior to the primary pulverization, the cellulose-containing raw material is preferably coarsely pulverized into chips or cuboids. The size of the cellulose-containing raw material in the form of chips is preferably 1 to 50 mm square, more preferably 1 to 30 mm square. By roughly crushing into 1-50 mm square chips, primary crushing can be performed efficiently and easily. In addition, the magnitude | size of the cellulose containing raw material after coarse grinding can be measured using a caliper.

  Examples of the coarse pulverization method include a method described in JP2010-270289A, that is, a method using a cutting machine such as a shredder, a rotary cutter, or a slitter cutter.

  Moreover, when using a sheet-like cellulose-containing raw material, it is preferable to use a shredder or a slitter cutter.

  As a method of mechanically pulverizing a cellulose-containing raw material by applying a compression shear force, that is, a method of primary pulverization, conventionally used impact type pulverizers such as a cutter mill, a hammer mill, a pin mill, etc. and extrusion Although the method of pulverizing using a machine can be mentioned, the cellulose-containing raw material is less likely to become bulky due to the cotton-like material, a cellulose-containing raw material having a desired bulk density and average particle diameter is obtained, and the handleability is improved. A method using an extruder is preferred.

  The pulverization treatment (primary pulverization) using an extruder can be performed according to a known method.

  A cellulose-containing raw material whose bulk density and average particle diameter are adjusted by the primary pulverization (hereinafter also referred to as a cellulose-containing raw material obtained by primary pulverization or a cellulose-containing raw material after primary pulverization) is obtained. The cellulose content in the remaining components when water is removed from the raw material after the primary pulverization is preferably 20% by weight or more, more preferably 40% without any change in the cellulose content due to the primary pulverization. % Or more, more preferably 60% by weight or more. Although the cellulose crystallization degree is reduced by the primary pulverization, the cellulose crystallization degree of the cellulose-containing raw material after the primary pulverization is preferably 60% or more.

The bulk density of the cellulose-containing raw material after the primary pulverization, 100 kg / ^{m 3} or more, more preferably 120 kg / ^{m 3} or more, more preferably 150 kg / ^{m 3} or more. When the bulk density is 100 kg / m ³ or more, the cellulose-containing raw material has an appropriate volume, so that handleability is improved. Moreover, since the raw material charge amount can be increased to the pulverizer used for the secondary pulverization, the processing capacity is improved. On the other hand, the upper limit of the bulk density, from the viewpoint of improving the handling properties and productivity, preferably 500 kg / ^{m 3} or less, more preferably 400 kg / ^{m 3} or less, more preferably 350 kg / ^{m 3} or less. From these viewpoints, the bulk density is preferably from 100 to 500 kg / ^{m 3,} more preferably 120~400kg / ^{m 3,} more preferably 150~350kg / ^{m 3.} In addition, in this specification, the bulk density of a cellulose containing raw material can be measured by the method as described in the below-mentioned Example.

  Further, the average particle size of the cellulose-containing raw material after the primary pulverization is preferably 1.0 mm or less, more preferably 0.7 mm or less, and further preferably 0.5 mm or less. When the average particle size is 1.0 mm or less, the cellulose-containing raw material can be efficiently dispersed in the pulverizer when it is supplied to the pulverizer used for the secondary pulverization. The diameter can be reached. On the other hand, the lower limit of the average particle diameter is preferably 0.01 mm or more and more preferably 0.05 mm or more from the viewpoint of improving productivity. From these viewpoints, the average particle size is preferably 0.01 to 1.0 mm, more preferably 0.01 to 0.7 mm, and even more preferably 0.05 to 0.5 mm. Further, the water content of the cellulose-containing raw material after the primary pulverization is preferably more than 4.5% by weight, and preferably 10% by weight or less.

(Method for preparing cellulose-containing raw material with adjusted water content)
On the other hand, the method for adjusting the moisture content of the cellulose-containing raw material is not limited as long as it includes a step of performing a drying treatment, and a known drying method may be appropriately selected. Examples of the drying method include hot air heat receiving drying method, conductive heat receiving drying method, dehumidifying air drying method, cold air drying method, microwave drying method, infrared drying method, sun drying method, vacuum drying method, freeze drying method and the like. It is done. These drying methods may be performed singly or in combination of two or more, and the conditions (temperature, drying means, drying time, pressure, etc.) in the drying method can be appropriately set. The drying process can be either a batch process or a continuous process, and a process similar to the coarse pulverization process performed before the primary pulverization of the cellulose-containing raw material may be performed before the drying process.

  A cellulose-containing raw material whose water content is adjusted by the drying treatment is obtained. The moisture content of the dried cellulose-containing raw material is preferably 4.5% by weight or less from the viewpoint of easily secondary pulverization and improving the durability of the polylactic acid resin molded product, and is 0.2 to 4.3% by weight. % Is more preferable, 0.4 to 3.5% by weight is more preferable, and 0.6 to 3.0% by weight is more preferable. Generally available cellulose-containing raw materials such as commercially available pulps, papers used as biomass resources, woods, plant stems / leaves, plant cereals, etc. are 5% by weight or more, usually about 5-30% by weight. Contains water.

  Moreover, it is preferable that the bulk density of the cellulose-containing raw material whose water content is adjusted has the same value as the bulk density of the cellulose raw material after the primary pulverization. In addition, the cellulose content in the remaining component when water is removed from the raw material after the drying treatment is preferably 20% by weight or more, more preferably 40% by weight or more without changing the cellulose content by the drying treatment. More preferably, it is 60% by weight or more. Further, the cellulose crystallinity does not vary with the drying treatment, and the cellulose crystallinity after the drying treatment is usually 80% or more.

  Furthermore, the average particle size of the cellulose-containing raw material whose water content has been adjusted is preferably more than 1.0 mm and not more than 50.0 mm, and more preferably more than 2.0 mm and not more than 50.0 mm.

  Next, the cellulose-containing raw material obtained by the primary pulverization or the drying treatment, or the cellulose-containing raw material that has not been subjected to the primary pulverization or the drying treatment is used as it is before the primary pulverization. The cellulose-containing raw material subjected only to the coarse pulverization treatment is subjected to secondary pulverization in order to be amorphous.

  As the pulverizer used for the secondary pulverization, a medium pulverizer is preferable. The medium type pulverizer includes a container drive type pulverizer and a medium stirring type pulverizer. Examples of the container-driven crusher include a rolling mill, a vibration mill, a planetary mill, and a centrifugal fluid mill. Among these, a vibration mill is preferable from the viewpoint of high grinding efficiency and improved productivity. As a medium agitation pulverizer, a tower type pulverizer such as a tower mill; an agitator tank type pulverizer such as an attritor, an aquamizer and a sand grinder; a distribution tank type pulverizer such as a visco mill and a pearl mill; a distribution pipe type pulverizer; For example, a continuous dynamic type pulverizer. Among these, a stirring tank type pulverizer is preferable from the viewpoint of high pulverization efficiency and improved productivity. In the case of using a medium stirring pulverizer, the peripheral speed of the tip of the stirring blade is preferably 0.5 to 20 m / s, more preferably 1 to 15 m / s. In addition, the kind of grinder can refer to "Progress of chemical engineering 30th particle control" (Chemical Engineering Society, Tokai branch edition, published on October 10, 1996, Kashiwa Shoten). Moreover, as a processing method, either a batch type or a continuous type may be sufficient.

  There is no restriction | limiting in particular as a material of the medium of a grinder, For example, iron, stainless steel, an alumina, a zirconia, silicon carbide, a silicon nitride, glass etc. are mentioned. There is no restriction | limiting in particular as a shape of a medium, A ball | bowl, a rod, a tube, etc. are mentioned. The rod is a rod-shaped medium, and a rod having a cross section of a polygon such as a quadrangle or a hexagon, a circle, or an ellipse can be used.

  When the pulverizer is a vibration mill and the medium is a rod, the outer diameter of the rod is preferably 0.5 to 200 mm, more preferably 1.0 to 100 mm, and further preferably 5 to 50 mm. If the size of the rod is within the above range, the desired pulverization force can be obtained, and the cellulose can be efficiently amorphousized without contamination of the cellulose-containing raw material by mixing fragments of the rod and the like. it can. From the viewpoint of increasing the contact frequency between the cellulose-containing raw material and the rod and improving the grinding efficiency, it is preferable to use a plurality of rods.

  The treatment time cannot be determined unconditionally depending on the type of pulverizer, the type of medium, the size, the filling rate, and the like. -20 hr, more preferably 0.10 to 10 hr, still more preferably 0.10 to 5 hr. Although processing temperature does not have a restriction | limiting in particular, From a viewpoint of preventing deterioration by a heat | fever, Preferably it is 5-250 degreeC, More preferably, it is 10-200 degreeC.

  Thus, cellulose having a crystallinity of less than 50% is obtained.

  The cellulose thus obtained is amorphized to a degree of crystallinity of less than 50%, but from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and improving the handleability, the average The particle size is preferably 150 μm or less, and more preferably 50 μm or less. Moreover, it is preferable that it is 90 nm or more from a viewpoint of making the intensity | strength and flexibility of a polylactic acid resin composition compatible, and it is more preferable that it is 100 nm or more. Therefore, the cellulose obtained by the secondary pulverization may be appropriately subjected to a classification step, a sieving step, etc. to adjust the particle size. Moreover, you may dry the amorphous cellulose according to a well-known method. In addition, the average particle diameter of a cellulose can be measured by the method as described in the below-mentioned Example.

  In the present invention, from the viewpoint of further improving impact resistance while maintaining the strength and flexibility of the resulting polylactic acid resin molded article, the cellulose contained in the polylactic acid resin composition contains less than 50% crystals. It is preferable that the cellulose having a degree of conversion is obtained by reducing the particle size so that the average particle size is 30 μm or less.

  As a method for reducing the particle size, a pulverization aid is added to cellulose adjusted to have a crystallinity of less than 50%, and pulverization (hereinafter also referred to as tertiary pulverization) is performed by a pulverizer. A method is mentioned. The cellulose used for the third pulverization is not particularly limited as long as the crystallinity is adjusted to be less than 50%, but the crystallinity is adjusted to be less than 50% by the mechanical treatment. Cellulose is preferred. Accordingly, the cellulose having a crystallinity of less than 50% contained in the composition of the present invention is further pulverized into the cellulose obtained by the mechanical treatment, that is, the cellulose obtained by treatment with a pulverizer. It is preferably obtained by adding an auxiliary agent and pulverizing.

  As the pulverizer used for the tertiary pulverization, a medium pulverizer is preferable, and the same pulverizer as suitable for the secondary pulverization is exemplified. Note that the pulverizer used for the secondary pulverization and the pulverizer used for the tertiary pulverization may be the same or different.

  There is no restriction | limiting in particular as a material of the medium of a grinder, For example, iron, stainless steel, an alumina, a zirconia, silicon carbide, a silicon nitride, glass etc. are mentioned. The shape of the medium is not particularly limited and includes balls, rods, tubes, etc. From the viewpoint of improving the atomization efficiency of cellulose, as a pulverizer used for the third pulverization, a vibration mill filled with a rod is used. preferable.

  The outer diameter of the rod is preferably 0.5 to 200 mm, more preferably 1 to 100 mm, and even more preferably 5 to 50 mm, and the length of the rod is particularly shorter than the length of the container of the pulverizer. It is not limited. If the size of the rod is within the above range, a desired grinding force can be obtained, and the average particle size of cellulose can be efficiently reduced.

  As a grinding aid used for the tertiary grinding, for example, a grinding aid described in JP 2010-270289 A, that is, an alcohol from the viewpoint of promoting adsorption to cellulose by interaction with a hydroxyl group in cellulose. , Aliphatic amide, aromatic carboxylic acid amide, rosin acid amide, metal salt of fatty acid, metal salt of aromatic sulfonic acid dialkyl ester, metal salt of phenylphosphonic acid, metal salt of phosphate ester, metal salt of rosin acid, fatty acid Examples include esters, carbohydrazides, N-substituted ureas, salts of melamine compounds, uracils and polyethers. These may be used alone or in combination of two or more at any ratio. Among them, from the viewpoint of improving the thermal stability of the polylactic acid resin composition, alcohol, aliphatic amide, aromatic carboxylic acid amide, metal salt of fatty acid, metal salt of phenylphosphonic acid, metal salt of phosphate ester, fatty acid ester And at least one selected from the group consisting of polyethers and polyethers, and from the viewpoint of improving the pulverization efficiency of cellulose and the impact resistance of the polylactic acid resin molded article, alcohols, aliphatic amides, metal salts of fatty acids, phenylphosphonic acid At least one selected from the group consisting of metal salts, fatty acid esters and polyethers is more preferred. Moreover, the plasticizer mentioned later can also be previously used at the time of dispersion | distribution of a cellulose as a grinding aid.

  In the present invention, the addition amount of the grinding aid is preferably 0.1 to 100 parts by weight, more preferably 0.5 to 50 parts by weight with respect to 100 parts by weight of cellulose to be subjected to the third grinding. More preferably, it is 1.0-30 weight part, More preferably, it is 2-20 weight part. If the addition amount of the grinding aid is 0.1 parts by weight or more with respect to 100 parts by weight of the cellulose to be subjected to the tertiary grinding, the average particle size of the cellulose can be reduced. For example, cellulose having an average particle size of 30 μm or less can be obtained efficiently.

  The processing time of the tertiary pulverization can be appropriately adjusted according to the type of pulverizer, the type, size, and filling rate of the medium filled in the pulverizer, from the viewpoint of efficiently reducing the average particle size of cellulose. , Preferably 0.01 to 50 hr, more preferably 0.05 to 20 hr, still more preferably 0.10 to 10 hr, still more preferably 0.10 to 5 hr, still more preferably 0.10 to 3.5 hr. The pulverization temperature is not particularly limited, but is preferably 5 to 250 ° C, more preferably 10 to 200 ° C, and still more preferably 15 to 150 ° C from the viewpoint of preventing thermal deterioration.

  Thus, micronized cellulose in which strong aggregation of cellulose particles is suppressed is obtained by the tertiary pulverization. The average particle size of the micronized cellulose is preferably 0.1 to 30 μm, more preferably 0.1 to 20 μm.

  In addition, cellulose having a crystallinity of less than 50% obtained by secondary pulverization, and having a crystallinity of less than 50% obtained by the secondary pulverization and tertiary pulverization, and 30 μm or less. Cellulose having an average particle diameter may be mixed with iron from a pulverizer or its medium during pulverization. Therefore, in the present invention, from the viewpoint of improving impact resistance and color tone, the iron content of the cellulose used in the present invention is preferably 500 ppm or less, more preferably 300 ppm or less, further preferably 100 ppm or less, more preferably 50 ppm or less, More preferably, it is 30 ppm or less, More preferably, it is 20 ppm or less. Moreover, from a viewpoint of improving productivity, 0 ppm or more is preferable and 1 ppm or more is more preferable.

  In the present invention, from the viewpoint of further improving the flexibility of the polylactic acid resin composition, cellulose having a crystallinity of less than 50% obtained by the secondary pulverization, the secondary pulverization and the tertiary Treating the surface of cellulose obtained by grinding with a crystallinity of less than 50% and an average particle size of 30 μm or less with a surface treatment agent such as a silane coupling agent or a titanium coupling agent Can do.

  The surface treatment agent is not particularly limited and known ones can be used, and examples include 3-aminopropyltriethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-isocyanatopropyltriethoxysilane.

  The treatment amount of the surface treatment agent is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the surface-treated cellulose from the viewpoint of achieving both strength and flexibility of the polylactic acid resin composition. 3 to 3 parts by weight is more preferable, and 0.5 to 2 parts by weight is further preferable.

  The surface treatment method is not particularly limited, and can be performed according to a known method.

  The content of cellulose having a crystallinity of less than 50% is 5 to 350 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of improving the strength and impact resistance of the polylactic acid resin molded body. 5-300 weight part is preferable, 5-200 weight part is more preferable, 5-100 weight part is further more preferable, 5-50 weight part is further more preferable, 10-40 weight part is further more preferable.

[Glass fiber]
The composition of this invention contains glass fiber from a viewpoint which improves the color tone of an injection molded product and improves a bending elastic modulus.

  Any glass fiber can be used without particular limitation as long as it is made by melt spinning a known glass into a filament fiber.

  The average fiber diameter of the glass fiber is preferably 6 to 23 μm, more preferably 6 to 13 μm. The average fiber length is preferably 1.5 to 13 mm, more preferably 2.5 to 7 mm. The average fiber length of the glass fibers can be determined by observing arbitrary 100 fibers with an optical microscope and calculating the number average. The average fiber diameter can be obtained by the same method as described above for the cross-sectional area obtained by cutting the glass fiber. If the fiber diameter has a major axis and a minor axis, the major axis is used for calculation.

  In the present invention, a sizing agent is preferably attached to the glass fiber. As the sizing agent to be attached to the glass fiber, a silane coupling agent, a urethane resin, a polyester resin, an epoxy resin, a polylactic acid resin, or the like can be used. For example, as a silane coupling agent having an epoxy group, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ- Glycidoxypropylmethyldiethoxysilane or the like can be preferably used. The sizing agent can be attached in accordance with a known method. Moreover, the amount of adhesion can also be set as appropriate.

  The content of the glass fiber is 1 to 25 parts by weight, preferably 2 to 20 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of improving the color tone and the flexural modulus of the polylactic acid resin composition. 3-20 weight part is more preferable, 4-18 weight part is further more preferable, and 5-15 weight part is further more preferable. Moreover, 2-100 weight part is preferable with respect to 100 weight part of cellulose whose crystallinity is less than 50% from a viewpoint of improving the color tone and bending elastic modulus of a polylactic acid resin composition, and 2-80 weight part is preferable. More preferably, 5-70 weight part is further more preferable, and 10-50 weight part is further more preferable.

[Rubber component]
The composition of the present invention contains a rubber component from the viewpoint of absorbing impact and improving impact resistance. In the present specification, the “rubber component” refers to an impact resistant absorbent that absorbs impact and improves impact resistance, and is also simply an impact absorbent or an impact resistance improver.

The type of rubber is not particularly limited as long as it is composed of a polymer component having rubber elasticity. For example, the rubber | gum comprised from what polymerized natural rubber, an acrylic component, a silicone component, a styrene component, a nitrile component, a conjugated diene component, a urethane component, an ethylene propylene component, etc. is mentioned. Preferred rubbers include, for example, acrylic components such as ethyl acrylate units and butyl acrylate units, silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, styrene components such as styrene units and α-methylstyrene units, acrylonitrile units, and the like. It is a rubber constituted by polymerizing a nitrile component such as a methacrylonitrile unit or a conjugated diene component such as a butanediene unit or an isoprene unit. Also preferred is a rubber composed of a combination of two or more of these components, for example,
(1) Rubber composed of components obtained by copolymerizing acrylic components such as ethyl acrylate units and butyl acrylate units and silicone components such as dimethylsiloxane units and phenylmethylsiloxane units,
(2) Rubber composed of an acrylic component such as an ethyl acrylate unit or a butyl acrylate unit and a component obtained by copolymerizing a styrene component such as a styrene unit or an α-methylstyrene unit,
(3) rubber composed of components obtained by copolymerizing acrylic components such as ethyl acrylate units and butyl acrylate units and conjugated diene components such as butanediene units and isoprene units;
(4) It is composed of an acrylic component such as an ethyl acrylate unit or a butyl acrylate unit, a silicone component such as a dimethylsiloxane unit or a phenylmethylsiloxane unit, and a component obtained by copolymerizing a styrene component such as a styrene unit or an α-methylstyrene unit. And rubber. Especially, from a viewpoint of improving impact resistance, (1) and (4) are preferable, and (1) is more preferable. In addition to these components, a rubber obtained by copolymerizing and crosslinking a crosslinkable component such as a divinylbenzene unit, an allyl acrylate unit, or a butylene glycol diacrylate unit is also preferable.

  The rubber may be a multilayer structure polymer. The type of layer other than rubber is not particularly limited as long as it is composed of a polymer component having thermoplasticity, but a polymer component having a glass transition temperature higher than that of the rubber layer is preferable. Polymers having thermoplastic properties include unsaturated carboxylic acid alkyl ester units, glycidyl group-containing vinyl units, unsaturated dicarboxylic anhydride units, aliphatic vinyl units, aromatic vinyl units, and vinyl cyanide units. Examples include polymers containing at least one unit selected from units, maleimide units, unsaturated dicarboxylic acid units, and other vinyl units, among which unsaturated carboxylic acid alkyl ester units, unsaturated A polymer containing at least one unit selected from a glycidyl group-containing unit or an unsaturated dicarboxylic acid anhydride unit is preferred, and at least selected from an unsaturated glycidyl group-containing unit or an unsaturated dicarboxylic acid anhydride unit. More preferred are polymers containing one or more units.

  Among these, from the viewpoint of improving impact resistance and color tone, a core-shell type rubber containing the rubber component in the core layer and the polymer component having the thermoplasticity in the shell layer is preferable. The glass transition temperature of the rubber component of the core layer is preferably 20 ° C. or less, more preferably 0 ° C. or less, and the glass transition temperature of the polymer component of the shell layer is preferably higher than the glass transition temperature of the rubber component of the core layer. .

  Specifically, the core layer is a butyl acrylate polymer, the shell layer is a methyl methacrylate polymer, the core layer is a butyl acrylate / styrene copolymer, and the shell layer is a methyl methacrylate polymer. Type rubber; styrene / butadiene core-shell type rubber such as core layer of styrene / butadiene polymer and shell layer of methyl methacrylate polymer; core layer of silicone / acrylic polymer and shell layer of methyl methacrylate polymer; Examples include silicone / acrylic core-shell type rubbers such as silicone / acrylic copolymers and shell layers such as methyl methacrylate / glycidyl methacrylate copolymers. “Metablene S-2001” (core shell) manufactured by Mitsubishi Rayon Co., Ltd. Type silicone / acrylic rubber), "Metabrene S-2006" (core shell type silicone・ Acrylic rubber), “methabrene W-450A” (core shell type acrylic rubber), “methabrene C-223A” (core shell type MBS rubber, MMA / butadiene / styrene), “LA-2140E” manufactured by Kuraray (acrylic heat) (Plastic resin) etc. can be used suitably.

  The content of the rubber component is 1 to 45 parts by weight, preferably 2 to 40 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of improving the impact resistance and moldability of the polylactic acid resin composition. 3 to 35 parts by weight is more preferable, 5 to 30 parts by weight is further preferable, and 10 to 30 parts by weight is further preferable.

  Moreover, from the viewpoint of improving impact resistance, color tone, and flexural modulus relative to 100 parts by weight of the polylactic acid resin, the total amount (total content) of the glass fiber and the rubber component is preferably 2 to 50 parts by weight, 5-40 weight part is more preferable, and 10-40 weight is further more preferable.

  The weight ratio of the rubber component to the glass fiber (rubber component / glass fiber) is preferably 0.1 to 10, more preferably 0.2 to 9, from the viewpoint of improving impact resistance, color tone, and flexural modulus. 0.3-8 are more preferable and 0.3-6 are more preferable.

  The polylactic acid resin composition of the present invention preferably further contains a plasticizer in addition to the polylactic acid resin, cellulose having a crystallinity of less than 50%, glass fibers, and a rubber component.

[Plasticizer]
Cellulose having a crystallinity of less than 50% contained in the polylactic acid resin composition of the present invention has a significantly reduced crystallinity compared to cellulose used in conventional resin compositions. Therefore, it plays the role of a plasticizer by itself. From the viewpoint of further improving the strength and flexibility of the polylactic acid resin composition and improving the impact resistance, the polylactic acid resin composition of the present invention is It is preferable to contain a plasticizer.

  The plasticizer is not particularly limited, and examples thereof include known ones. Examples thereof include phthalates such as di-n-octyl phthalate, di-2-ethylhexyl phthalate, dibenzyl phthalate, and diisodecyl phthalate, and isophthalates such as dioctyl isophthalate. Itacones such as acid esters, adipic acid esters such as di-n-butyl adipate and dioctyl adipate, maleic acid esters such as di-n-butyl malate, citrate esters such as acetyltri-n-butyl citrate, and monobutyl itaconate Carboxylic acid ester such as acid ester, oleic acid ester such as butyl oleate, diacetyl caprylic acid monoglyceride, diacetyl lauric acid monoglyceride, ricinoleic acid monoglyceride, decaglycerin monooleate; Phosphate esters such as phosphate and tris (ethoxyethoxyethyl) phosphate; polyethylene glycol (hereinafter PEG), PEG diacetate, polypropylene glycol (hereinafter PPG), PEG-PPG-PEG block polymer, PPG-PEG-PPG block polymer, etc. Polyalkylene glycols; lactic acid oligomer esters such as triethylene glycol monomethyl ether lactic acid oligomer ester; rosin acid esters such as diethylene glycol rosin ester acetate can be used. Among these, carboxylic acid esters and / or phosphate esters are preferable from the viewpoint of improving flexibility, and among them, two or more in the molecule from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition. An ester compound (hereinafter referred to as “AO addition ester compound”) having an average of 0.5 to 5 moles of an alkylene oxide having 2 to 3 carbon atoms per hydroxyl group is added to at least one alcohol component constituting the ester. ))).

As the carboxylic acid ester, an oligoester represented by the following formula (I) is preferable from the viewpoint of improving strength and flexibility.
R ⁶ O—CO—R ⁷ —CO — [(OR ⁸ ) _a —OCO—R ⁷ —CO—] _b OR ⁶ (I)
Wherein R ⁶ is an alkyl group having 1 to 4 carbon atoms, R ⁷ is an alkylene group having 2 to 4 carbon atoms, R ⁸ is an alkylene group having 2 to 6 carbon atoms, and a is 1 to 6 And b represents a number from 1 to 6, provided that all R ⁶ may be the same or different, all R ⁷ may be the same or different, and all R ⁸ are the same or different. May be)

R ⁶ in formula (I) represents an alkyl group having 1 to 4 carbon atoms, and two of them exist in one molecule and exist at both ends of the molecule. R ⁶ may be linear or branched as long as it has 1 to 4 carbon atoms. The number of carbon atoms of the alkyl group is preferably 1 to 4 and more preferably 1 to 2 from the viewpoint of improving the compatibility with the polylactic acid resin and expressing the plasticizing effect. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, and a tert-butyl group. Among them, the compatibility with a polylactic acid resin is improved and a plasticizing effect is obtained. From the viewpoint of expression, a methyl group is preferable. However, all R ⁶ may be the same or different.

R ⁷ in formula (I) represents an alkylene group having 2 to 4 carbon atoms, and a linear alkylene group is a preferred example. Specific examples include an ethylene group, a 1,3-propylene group, and a 1,4-butylene group. Among them, from the viewpoint of improving the compatibility with a polylactic acid resin and expressing a plasticizing effect, an ethylene group, A 1,3-propylene group is preferred, an ethylene group is more preferred, and an ethylene group and a 1,4-butylene group are preferred, and an ethylene group is more preferred from the viewpoint of developing a plasticizing effect and improving economic efficiency. However, all R ⁷ may be the same or different.

R ⁸ in the formula (I) represents an alkylene group having 2 to 6 carbon atoms, and OR ⁸ represents an oxyalkylene group. R ⁸ may be linear or branched as long as it has 2 to 6 carbon atoms. The number of carbon atoms of the alkylene group is preferably 2 to 6 and more preferably 2 to 3 from the viewpoint of improving compatibility with the polylactic acid resin and exhibiting a plasticizing effect. Specifically, ethylene group, 1,2-propylene group, 1,3-propylene group, 1,2-butylene group, 1,3-butylene group, 1,4-butylene group, 2-methyl-1,3 -Propylene group, 1,2-pentylene group, 1,4-pentylene group, 1,5-pentylene group, 2,2-dimethyl-1,3-propylene group, 1,2-hexylene group, 1,5-hexylene Group, 1,6-hexylene group, 2,5-hexylene group, 3-methyl-1,5-pentylene group, among others, the viewpoint of improving the compatibility with polylactic acid resin and developing the plasticizing effect Therefore, an ethylene group, a 1,2-propylene group, and a 1,3-propylene group are preferable. However, all R ⁸ may be the same or different.

  a shows the average repeating number of an oxyalkylene group, and is a number of 1-6. When a becomes large, the ether group value of the ester compound represented by the formula (I) increases, and it is easily oxidized and the stability is lowered. From the viewpoint of improving the compatibility with the polylactic acid resin, the number of 1 to 4 is preferable, and the number of 1 to 3 is more preferable.

  b shows an average degree of polymerization and is a number of 1-6. From the viewpoint of improving the compatibility with the polylactic acid resin and improving the plasticizing effect and plasticizing efficiency, the number of 1 to 4 is preferable.

Specific examples of the compound represented by the formula (I) include an ester in which R ⁶ is a methyl group, R ⁷ is an ethylene group, R ⁸ is an ethylene group, a is 2 and b is 1.5, R ⁶ Is an ethyl group, R ⁷ is a 1,4-butylene group, R ⁸ is a 1,3-propylene group, a is an ester of 1, b is 2, R ⁶ is a butyl group, R ⁷ is 1,3- A propylene group, R ⁸ is an ethylene group, a is an ester of 3, b is 1.5, R ⁶ is a methyl group, R ⁷ is an ethylene group, R ⁸ is a 1,6-hexylene group, 1 and b are 3 esters, and these may be used alone or in combination of two or more. Among these, R ⁶ is all methyl group, R ⁷ is ethylene group or 1,4-butylene group, R ⁸ is ethylene group or 1,3-propylene group, a is a number of 1 to 3, b Is preferably a compound in which R ⁶ is a methyl group, R ⁷ is an ethylene group or a 1,4-butylene group, R ⁸ is an ethylene group or a 1,3-propylene group, and a is A compound having 1 to 3 and b being 1 to 3 is more preferable.

  From the viewpoint of improving volatility, at least one dibasic acid selected from succinic acid, glutaric acid, and adipic acid, diethylene glycol, triethylene glycol, 1,2-propanediol, and 1,3-propane An oligoester of at least one dihydric alcohol selected from diols [in formula (I), b = 1.2 to 3] is preferable.

  As the phosphate ester, from the viewpoint of improving flexibility, the following formula (II):

(Wherein R ⁹ , R ¹⁰ and R ¹¹ each independently represent an alkyl group having 1 to 4 carbon atoms, and A ¹ , A ² and A ³ each independently represents an alkylene group having 2 or 3 carbon atoms. D, e and f are each independently a positive number indicating the average number of moles added of the oxyalkylene group, and d + e + f is a number satisfying 4 to 12)
The compound represented by these is preferable.

  The compound represented by the formula (II) is a polyether-type phosphate triester, which may be a symmetric structure or an asymmetric structure. However, from the viewpoint of ease of production, a symmetric structure phosphate triester is preferable.

R ⁹ , R ¹⁰ and R ¹¹ each independently represent an alkyl group having 1 to 4 carbon atoms, and may be linear or branched. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group, and an ethyl group, a propyl group, and a butyl group are preferable.

A ¹ , A ² , and A ³ each independently represent an alkylene group having 2 or 3 carbon atoms, and may be linear or branched. Specific examples include an ethylene group, an n-propylene group, and an isopropylene group. A ¹ , A ² , and A ³ form an oxyalkylene group (alkylene oxide) with an adjacent oxygen atom to form a repeating structure in the compound represented by the formula (II).

  d, e and f are each independently a positive number indicating the average number of moles added of the oxyalkylene group, and d + e + f is 4 to 12, which improves the compatibility with the polylactic acid resin, and has a plasticizing effect. From the viewpoint of improving the ratio, it is preferably a number satisfying 5 to 10. By improving the plasticizing effect, a sufficient plasticizing effect can be imparted to the polylactic acid resin even with a small addition amount.

  Specific examples of the compound represented by the formula (II) include the formula (III):

Tris (ethoxyethoxyethyl) phosphate represented by the formula [In the formula (II), R ⁹ , R ¹⁰ , R ¹¹ are all ethyl groups, A ¹ , A ² , A ³ are all ethylene groups, d, e, f is 2 and d + e + f = 6], tris (methoxyethoxyethyl) phosphate, tris (propoxyethoxyethyl) phosphate, tris (butoxyethoxyethyl) phosphate, tris (methoxyethoxyethoxyethyl) phosphate, tris ( Asymmetric polyether type phosphorus such as symmetric polyether type phosphoric acid triester such as ethoxyethoxyethoxyethyl) phosphate, bis (ethoxyethoxyethyl) methoxyethoxyethoxyethyl phosphate, bis (methoxyethoxyethoxyethyl) ethoxyethoxyethyl phosphate An asymmetric polyether-type phosphate ester obtained by phosphoric acid esterification of an acid triester or a mixture of a polyoxyethylene adduct or a polyoxypropylene adduct of an alcohol having 1 to 4 carbon atoms to satisfy the formula (II) However, from the viewpoint of improving flexibility, tris (ethoxyethoxyethyl) phosphate is preferable.

  Moreover, as said AO addition ester compound, it has a plasticizer as described in Unexamined-Japanese-Patent No. 2008-115372 and Unexamined-Japanese-Patent No. 2008-174718, ie, has two or more ester groups in a molecule | numerator, and comprises ester. An ester compound in which an average of 0.5 to 5 moles of an alkylene oxide having 2 to 3 carbon atoms per hydroxyl group is added as at least one of the alcohol components is exemplified. For example, an alkyleneoxy group having 2 or 3 carbon atoms per hydroxyl group Is preferably a compound obtained by polycondensation of an alcohol component such as an alkylene oxide adduct of alcohol with an average of 0.5 to 5 moles of addition and a known carboxylic acid component.

  The condensation polymerization of the alcohol component and the carboxylic acid component can be performed according to a known method, for example, a method described in JP-A-2008-174735.

  In the present invention, from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and improving the moldability, plasticity, and bleed resistance of the plasticizer, succinic acid or adipic acid and polyethylene glycol monomethyl ether At least one selected from the group consisting of an ester compound and an ester compound of acetic acid and an ethylene oxide adduct of glycerin or ethylene glycol is preferred, and an ester compound of succinic acid or adipic acid and polyethylene glycol monomethyl ether is more preferred.

  From the viewpoint of improving volatility, an ester compound of adipic acid and a diethylene glycol monomethyl ether / benzyl alcohol mixture (weight ratio: 1/1) is preferable.

  In addition, it is preferable that the AO addition ester compound is an all esterified saturated ester from the viewpoint of sufficiently exhibiting the function as a plasticizer.

The average molecular weight of the AO addition ester compound is preferably 250 to 700 from the viewpoint of making the strength and flexibility of the polylactic acid resin composition compatible and improving the bleed resistance and volatilization resistance of the plasticizer. More preferably, it is 300-600, More preferably, it is 350-550, More preferably, it is 400-500. The average molecular weight can be obtained by calculating the saponification value by the method described in JIS K0070 and calculating from the following formula.
Average molecular weight = 56,108 × (number of ester groups) / saponification value

  When the plasticizer contains the AO addition ester compound, the heat resistance of the polylactic acid resin composition and the compatibility with the polylactic acid resin and cellulose having a crystallinity of less than 50% are improved. Therefore, the bleed resistance is improved and the softening effect of the resin is also improved. By improving the softening of the resin, it is considered that when the resin is crystallized, the growth rate is also improved. As a result, since the polylactic acid resin retains flexibility even at a low mold temperature, crystallization of the polylactic acid resin proceeds in a short mold holding time, and good moldability is expected. Moreover, as a result of improving the compatibility with cellulose having a crystallinity of less than 50%, it is considered that both the excellent strength and flexibility of the polylactic acid resin composition can be achieved by the interaction between the two.

  As the plasticizer, the ester compound, that is, a carboxylic acid ester and / or a phosphoric acid ester and other plasticizers can be used. The content of the AO addition ester compound is not particularly limited, but is 60% by weight in the plasticizer from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and improving the bleed resistance of the plasticizer. The above is preferable, 70% by weight or more is more preferable, 90% by weight or more is further preferable, and substantially 100% by weight is even more preferable.

  The content of the plasticizer is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polylactic acid resin from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and obtaining impact resistance. -30 parts by weight is more preferred, 8-30 parts by weight is more preferred, and 8-20 parts by weight is even more preferred.

  In addition to the above, the polylactic acid resin composition of the present invention may further contain a crystal nucleating agent, a hydrolysis inhibitor and the like as appropriate.

[Crystal nucleating agent]
As the crystal nucleating agent, Japanese Patent Application Laid-Open No. 2008-115372 has been proposed from the viewpoint of making the strength and flexibility of the polylactic acid resin composition compatible and improving the moldability, heat resistance, impact resistance, and blooming resistance of the crystal nucleating agent. The crystal nucleating agent described in JP-A No. 2008-174718, that is, at least one selected from the group consisting of a compound having a hydroxyl group and an amide group in the molecule and a hydroxy fatty acid ester is preferable, and at least one of these And phenylphosphonic acid metal salt are more preferably used in combination, and it is more preferable to use a compound having a hydroxyl group and an amide group in the molecule and phenylphosphonic acid metal salt in combination.

  The compound having a hydroxyl group and an amide group in the molecule has two or more hydroxyl groups from the viewpoint of improving compatibility with the polylactic acid resin and achieving both strength and flexibility of the polylactic acid resin composition. Fatty acid bisamides having two or more amide groups are preferred, and methylene bis 12-hydroxystearic acid amide from the viewpoint of improving the moldability, heat resistance, impact resistance, and bloom resistance of the crystal nucleating agent of the polylactic acid resin composition. Further, alkylene bishydroxystearic acid amides such as ethylene bis 12-hydroxystearic acid amide and hexamethylene bis 12-hydroxystearic acid amide are more preferable, and ethylene bis 12-hydroxystearic acid amide is more preferable.

  The melting point of the compound having a hydroxyl group and an amide group in the molecule is preferably 65 ° C. or higher from the viewpoint of improving the dispersibility of the organic crystal nucleating agent during kneading and improving the crystallization rate of the polylactic acid resin composition. 70 to 220 ° C is more preferable, and 80 to 190 ° C is even more preferable.

  Specific examples of the hydroxy fatty acid ester include hydroxy fatty acid esters such as 12-hydroxystearic acid triglyceride, 12-hydroxystearic acid diglyceride, and 12-hydroxystearic acid monoglyceride. From the viewpoints of making the strength and flexibility of the polylactic acid resin composition compatible, and improving moldability, heat resistance, impact resistance, and bloom resistance of the organic crystal nucleating agent, 12-hydroxystearic acid triglyceride is preferable.

The phenylphosphonic acid metal salt is a metal salt of phenylphosphonic acid having a phenyl group which may have a substituent and a phosphonic group [—PO (OH) ₂ ]. Examples thereof include an alkyl group having 1 to 10 alkyl groups and an alkoxycarbonyl group having 1 to 10 carbon atoms in the alkoxy group. Specific examples of phenylphosphonic acid include unsubstituted phenylphosphonic acid, methylphenylphosphonic acid, ethylphenylphosphonic acid, propylphenylphosphonic acid, butylphenylphosphonic acid, dimethoxycarbonylphenylphosphonic acid, and diethoxycarbonylphenylphosphonic acid. And unsubstituted phenylphosphonic acid is preferred.

  Examples of metal salts of phenylphosphonic acid include lithium, sodium, magnesium, aluminum, potassium, calcium, barium, copper, zinc, iron, cobalt, nickel, and other salts, which improve the impact resistance of the polylactic acid resin moldings. From the point of view, zinc salts are preferred.

  In the present invention, as a crystal nucleating agent, when a phenylphosphonic acid metal salt is used in combination with at least one selected from the group consisting of a compound having a hydroxyl group and an amide group in the molecule and a hydroxy fatty acid ester, these ratios are: From the viewpoint of expressing the effect of the present invention, at least one selected from the group consisting of a compound having a hydroxyl group and an amide group in the molecule and a hydroxy fatty acid ester / metal salt of phenylphosphonic acid (weight ratio) = 20 / 80-80 / 20 is preferred, 30/70 to 70/30 is more preferred, and 40/60 to 60/40 is even more preferred.

  The total content of the crystal nucleating agent is 0.05 to 5 parts by weight with respect to 100 parts by weight of the polylactic acid resin from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and obtaining impact resistance. Is preferable, 0.10 to 3 parts by weight is more preferable, 0.20 to 2 parts by weight is further preferable, and 0.20 to 1 part by weight is even more preferable.

[Hydrolysis inhibitor]
Examples of the hydrolysis inhibitor include carbodiimide compounds such as a polycarbodiimide compound and a monocarbodiimide compound, and a polycarbodiimide compound is preferable from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and improving moldability. From the viewpoint of improving the heat resistance and impact resistance of the polylactic acid resin composition and the bloom resistance of the hydrolysis inhibitor, a monocarbodiimide compound is preferred.

  Examples of the polycarbodiimide compound include poly (4,4′-diphenylmethanecarbodiimide), poly (4,4′-dicyclohexylmethanecarbodiimide) and the like, and examples of the monocarbodiimide compound include N, N′-di-2,6- Examples include diisopropylphenylcarbodiimide.

  The carbodiimide compounds may be used alone or in combination of two or more in order to satisfy the moldability, heat resistance, impact resistance and hydrolysis resistance of the polylactic acid resin composition. Poly (4,4′-dicyclohexylmethanecarbodiimide) is carbodilite LA-1 (manufactured by Nisshinbo Industries, Inc.), N, N′-di-2,6-diisopropylphenylcarbodiimide is stabuxol 1, and stabuxol 1-LF (Rhein). Chemie) can be purchased and used.

  The content of the hydrolysis inhibitor is preferably 0.05 to 3 parts by weight, preferably 0.10 to 2 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of improving the moldability of the polylactic acid resin composition. Is more preferable, and 0.20 to 1 part by weight is more preferable.

  In addition to the above, the polylactic acid resin composition of the present invention may further include other components such as a hindered phenol or phosphite antioxidant, or a hydrocarbon wax or a lubricant that is an anionic surfactant. Can be contained. The content of each of the antioxidant and the lubricant is preferably 0.05 to 3 parts by weight, and more preferably 0.10 to 2 parts by weight with respect to 100 parts by weight of the polylactic acid resin.

  Furthermore, the polylactic acid resin composition of the present invention includes an antistatic agent, an antifogging agent, a light stabilizer, an ultraviolet absorber, a pigment, an antifungal agent, an antibacterial agent, a foaming agent and a flame retardant as components other than those described above. Etc. can be contained in the range which does not impair the effect of this invention.

  The polylactic acid resin composition of the present invention can be prepared without particular limitation as long as it contains a polylactic acid resin, cellulose having a crystallinity of less than 50%, glass fibers, and a rubber component. When cellulose having a degree of less than 50% is mixed with polylactic acid resin, glass fiber, or rubber component, for example, cellulose having a predetermined particle size and a crystallinity of less than 50% is mixed with a twin-screw extruder or a melt A method of preparing a compound by kneading into a polylactic acid resin, glass fiber, or rubber component using a mixer may be used. In such a method, when feeding cellulose having a crystallinity of less than 50% to an extruder, the polylactic acid resin, glass fiber, and rubber components are first melted, and then the middle of the twin-screw extruder using a side feeder or the like. Alternatively, cellulose having a crystallinity of less than 50% may be fed.

  Since the polylactic acid resin composition of the present invention has good processability and can be processed at a low temperature of, for example, 200 ° C. or lower, there is an advantage that the plasticizer is hardly decomposed even when a plasticizer is used. It can be formed into a sheet and used for various applications.

<Polylactic acid resin molded product and method for producing the same>
The polylactic acid resin molded product of the present invention can be obtained by molding the polylactic acid resin composition of the present invention. Specifically, for example, using an extruder or the like, a polylactic acid resin, cellulose having a crystallinity of less than 50%, glass fibers, and a rubber component are melted as necessary. A hydrolysis inhibitor or the like is mixed, and then the obtained melt is filled into a mold by an injection molding machine or the like and molded. In order to promote the plasticity of the polylactic acid resin during melting, it may be melt-mixed in the presence of a supercritical gas.

  The polylactic acid resin molded article of the present invention can achieve both strength and flexibility while containing cellulose having a crystallinity of less than 50%.

  A preferred method for producing the polylactic acid resin molded article of the present invention is a step of melt-kneading a polylactic acid resin, a polylactic acid resin composition containing cellulose, glass fiber, and a rubber component having a crystallinity of less than 50% [below] And a step (hereinafter referred to as step (2)) of molding the melt obtained in step (1) with an injection molding machine.

  Specific examples of the step (1) include, for example, a step of melt kneading a polylactic acid resin, cellulose having a crystallinity of less than 50%, glass fiber, and a rubber component using a melt kneader. The melt kneader is not particularly limited, and examples thereof include a twin screw extruder. The melt kneading temperature is preferably 160 to 250 ° C, more preferably 165 to 230 ° C, and further preferably 170 to 210 ° C from the viewpoint of improving the moldability of the polylactic acid resin composition and preventing deterioration.

  In the present invention, after the step (1), after cooling to an amorphous state (that is, the condition that the degree of crystallinity measured by high angle X-ray diffraction is 1% or less), the step (2) is performed. The method of performing and the method of performing the step (2) immediately after cooling after the step (1) are preferred. From the viewpoint of expressing the effect of improving the crystallization rate, the step of cooling and immediately after the step (1) The method of performing (2) is more preferable.

  Specific examples of the step (2) include a step of filling a mold with a polylactic acid resin composition using an injection molding machine, and the like. The mold temperature in the step (2) is preferably 110 ° C. or lower, more preferably 90 ° C. or lower, and further preferably 80 ° C. or lower, from the viewpoint of improving the crystallization speed and improving workability. Moreover, 30 degreeC or more is preferable, 40 degreeC or more is more preferable, and 60 degreeC or more is further more preferable. From this viewpoint, the mold temperature is preferably 30 to 110 ° C, more preferably 40 to 90 ° C, and further preferably 60 to 80 ° C.

The holding time in the mold in the step (2) is preferably from 5 to 120 seconds, more preferably from 8 to 60 seconds, from the viewpoint of achieving a relative crystallinity of 60% or more and improving productivity. More preferred is 60 seconds. In the present specification, the relative crystallinity refers to the crystallinity represented by the following formula.
Relative crystallinity (%) = {(ΔHm−ΔHcc) / ΔHm × 100}
Specifically, the relative crystallinity was raised from 20 ° C. to 200 ° C. at a rate of temperature increase of 20 ° C./min using a DSC apparatus (Diamond DSC manufactured by PerkinElmer Co., Ltd.) at a rate of temperature increase of 20 ° C./min. After holding, the temperature was lowered from 200 ° C. to 20 ° C. at a temperature drop rate of −20 ° C./min, held at 20 ° C. for 1 minute, and then further increased from 20 ° C. to 200 ° C. at a temperature rising rate of 20 ° C./min as 2ndRUN. The absolute value ΔHcc of the cold crystallization enthalpy of the polylactic acid resin observed at 1st RUN and the crystal melting enthalpy ΔHm observed at 2nd RUN can be used.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited at all by these Examples.

[Melting point of resin]
The melting point of the resin is determined from the crystal melting endothermic peak temperature by the temperature rising method of differential scanning calorimetry based on JIS-K7121, using a DSC device (Perkin Elmer, Diamond DSC). The melting point is measured by increasing the temperature from 20 ° C. to 250 ° C. at a temperature increase rate of 10 ° C./min.

[Average particle size of amorphous cellulose and crystalline cellulose]
The average particle size of amorphous cellulose and crystalline cellulose means volume median particle size (D ₅₀ ), and laser diffraction / scattering particle size distribution measuring device “LA-920” (manufactured by Horiba, Ltd.) Use to measure. The measurement conditions are that ultrasonic treatment is performed for 1 minute before the particle size measurement, ethanol is used as a dispersion medium at the time of measurement, and the volume median particle size (D ₅₀ ) is measured at a temperature of 25 ° C.

[Bulk density of cellulose-containing raw material]
The bulk density is measured using “Powder Tester” manufactured by Hosokawa Micron. The measurement is performed by vibrating the sieve, dropping the sample through a chute, receiving it in a specified container (capacity 100 mL), and measuring the weight of the sample in the container. However, the sample made into cotton is dropped by passing through a chute without passing through a sieve, received in a specified container (capacity 100 mL), and calculated by measuring the weight of the sample in the container.

[Cellulose type I crystallinity]
Cellulose type I crystallinity is calculated based on the above formula by measuring the X-ray diffraction intensity of a sample using “Rigaku RINT 2500VC X-RAY diffractometer” manufactured by Rigaku Corporation under the following conditions. The measurement sample is produced by compressing a pellet having an area of 320 mm ² × thickness of 1 mm.
X-ray source: Cu / Kα-radiation
Tube voltage: 40 kv
Tube current: 120 mA
Measurement range: Diffraction angle 2θ = 5-45 °
Scan speed: 10 ° / min

[Water content of cellulose-containing raw materials]
The moisture content is measured at 150 ° C. using an infrared moisture meter (“FD-610”, manufactured by Kett Science Laboratory).

[Cellulose content]
The cellulose content is based on the holocellulose quantification method described on pages 1081 to 1082 of the Japan Analytical Chemistry Society, Analytical Chemistry Handbook (4th revised edition, published on November 30, 1991, published by Maruzensha). taking measurement.

[Iron content of amorphous cellulose and crystalline cellulose]
The iron content is measured using an ICP emission spectrometer (“ICPS-7510” manufactured by Shimadzu Corporation).

[Average molecular weight of plasticizer]
The average molecular weight is obtained by calculating the saponification value by the method described in JIS K0070 and calculating from the following formula.
Average molecular weight = 56,108 × (number of ester groups) / saponification value

Production example 1 of polylactic acid resin (crosslinked polylactic acid resin)
100 parts by weight of polylactic acid resin (manufactured by Nature Works, NW4032D) and 1 part by weight of a crosslinking agent (manufactured by Nisshinbo Co., Ltd., Carbodilite LA-1) at 210 ° C. with a twin screw extruder (Ikegai Iron Works, PCM-45). Melt-kneading and strand cutting were performed to obtain crosslinked polylactic acid resin pellets. In addition, the obtained pellet was dried for one day under reduced pressure at 70 ° C., and the water content was adjusted to 1% by weight or less.

Plasticizer Production Example 1 (Diester of succinic acid and triethylene glycol monomethyl ether)
A 3 L flask equipped with a stirrer, thermometer and dehydration tube was charged with 500 g of succinic anhydride, 2463 g of triethylene glycol monomethyl ether, and 9.5 g of paratoluenesulfonic acid monohydrate, and nitrogen (500 mL / min) was added to the space. While blowing, the reaction was carried out at 110 ° C. for 15 hours under reduced pressure (4 to 10.7 kPa). The acid value of the reaction solution was 1.6 (KOH mg / g). After adding 27 g of adsorbent KYOWARD 500SH (manufactured by Kyowa Chemical Industry Co., Ltd.) to the reaction solution and stirring and filtering at 80 ° C. and 2.7 kPa for 45 minutes, triethylene at a liquid temperature of 115 to 200 ° C. and a pressure of 0.03 kPa. After distilling off glycol monomethyl ether and cooling to 80 ° C., the residual liquid was filtered under reduced pressure to obtain a diester of succinic acid and triethylene glycol monomethyl ether as a filtrate. The obtained diester had an acid value of 0.2 (KOHmg / g), a saponification value of 276 (KOHmg / g), a hydroxyl value of 1 or less (KOHmg / g), and a hue of APHA200.

  Next, an example of producing cellulose having a crystallinity of less than 50% is shown. In this example, cellulose having a crystallinity of less than 50% is referred to as “amorphous cellulose”, and cellulose having a crystallinity of 50% or more is referred to as “crystalline cellulose”.

Amorphous cellulose production example 1 (amorphous cellulose A)
[Coarse grinding]
As a cellulose-containing raw material, sheet-like wood pulp [“Blue Bear Ultra Ether” manufactured by Borregard, 800 mm × 600 mm × 1.5 mm, cellulose content 96 wt% (content in remaining components excluding water from cellulose-containing raw material] ), Cellulose I type crystallinity 81%, moisture content 7.0 wt%, bulk density 200 kg / m ³ ] on a shredder (“MSX2000-IVP440F” manufactured by Meikoshosha), about 10 mm × 5 mm × 1.5 mm It was made into a chip-like pulp.

[Crushing process for amorphization (secondary grinding)]
200 g of the obtained chip-like pulp was put into a vibration mill (manufactured by Chuo Kako Co., Ltd., “MB-1”, container total capacity 3.5 L), and rod (cross-sectional shape: circular, diameter: 30 mm, length: 218 mm, 13 materials (stainless steel) were filled in a vibration mill and treated for 60 minutes under conditions of an amplitude of 8 mm and a rotational speed of 1200 rpm. The temperature during operation was 30 ° C.

  After completion of the treatment, drying was performed using a shelf dryer (a vacuum constant temperature dryer “DRV320DA” manufactured by ADVANTEC) so that the moisture content of the amorphous cellulose after drying was 0.8 wt%. The obtained amorphous cellulose A had a cellulose I type crystallinity of 0%, an average particle size of 30 μm, and an iron content of 10 ppm.

Amorphous cellulose production example 2 (amorphous cellulose B)
[Crushing process to reduce particle size (tertiary crushing)]
Amorphous cellulose A 60 g and (MeEO ₃ ) ₂ SA (diester of succinic acid and triethylene glycol monomethyl ether, prepared by the above-mentioned plasticizer production example 1) as a grinding aid are mixed, The entire amount of the mixture was put into a vibration mill (Chuo Kako Co., Ltd., “MB-1”, total container capacity 3.5 L), and rod (cross-sectional shape: circular, outer diameter: 30 mm, length: 218 mm, material) : Stainless steel) 13 pieces were filled in a vibration mill and pulverized for 15 minutes under conditions of an amplitude of 8 mm and a rotational speed of 1200 revolutions / minute to obtain amorphous cellulose B. The obtained amorphous cellulose B had a cellulose I-type crystallinity of 0%, an average particle size of 10 μm, and an iron content of 10 ppm.

Amorphous cellulose production example 3 (amorphous cellulose C)
Amorphous cellulose C was obtained in the same manner as in Production Example 2, except that the type of grinding aid was changed to DOA [bis (2-ethylhexyl) adipate, manufactured by Daihachi Chemical Co., Ltd., “DOA”]. The obtained amorphous cellulose C had a cellulose I type crystallinity of 0%, an average particle size of 10 μm, and an iron content of 10 ppm.

Amorphous cellulose production example 4 (amorphous cellulose D)
Amorphous cellulose was produced in the same manner as in Production Example 1 except that the amount of chip-like pulp used for pulverization for amorphization was changed to 150 g. Amorphous cellulose D was obtained by grinding. The obtained amorphous cellulose D had a cellulose I type crystallinity of 0%, an average particle size of 10 μm, and an iron content of 30 ppm.

Amorphous cellulose production example 5 (amorphous cellulose E)
Amorphous cellulose was produced in the same manner as in Production Example 1 except that the amount of chip-like pulp used for pulverization for amorphization was changed to 50 g. For this reason, amorphous cellulose E was obtained. The obtained amorphous cellulose E had a cellulose I type crystallinity of 0%, an average particle size of 10 μm, and an iron content of 300 ppm.

Examples 1 to 18 and Comparative Examples 1 to 10 (However, Examples 1 to 12 and 17 to 18 are reference examples)
As raw materials, polylactic acid resin, plasticizer, crystal nucleating agent, hydrolysis inhibitor, impact absorbent (rubber component), and filler (amorphous cellulose, crystalline cellulose, glass fiber, shown in Tables 1 to 5) These were melt kneaded at 190 ° C. using a twin screw extruder (PCM-45, manufactured by Ikekai Tekko Co., Ltd.) using carbon fibers, and strand cut was performed to obtain pellets of a polylactic acid resin composition. In addition, the obtained pellet was dried for one day under reduced pressure at 70 ° C., and the water content was adjusted to 1% by weight or less.

  The obtained pellets were injection molded using an injection molding machine (Japan Steel Works, J75E-D) with a cylinder temperature of 200 ° C., and a test piece [rectangular column shape with a mold temperature of 80 ° C. and a molding time of 60 seconds] Test pieces (125 mm × 12 mm × 6 mm and 63 mm × 12 mm × 5 mm), flat plate-like test pieces (40 mm × 60 mm × 3 mm)] were molded, and the characteristics were examined according to the methods of Test Examples 1 to 3 below. The results are shown in Tables 1-5.

<Test Example 1> [Strength (flexural modulus)]
For a prismatic test piece (125 mm × 12 mm × 6 mm), a bending test is performed using Tensilon (Orientec Tensilon Universal Testing Machine RTC-1210A) based on JIS K7203 with a crosshead speed set to 3 mm / min. To obtain the flexural modulus. The higher the value, the better the strength.

<Test Example 2> [Shock resistance]
The Izod impact strength (J / m) of the prismatic test piece (63 mm × 12 mm × 5 mm) was measured using an impact tester (Ueshima Seisakusho 863 type) based on JIS K7110. It shows that it is excellent in impact resistance, so that Izod impact strength (J / m) is high.

<Test Example 3> [Color tone]
About the flat test piece (40 mm x 60 mm x 3 mm), L value was measured using the color difference meter (Nippon Denshoku Industries Co., Ltd. SE2000). A higher L value indicates a better color tone.

In addition, the raw material in Tables 1-5 is as follows.
[Polylactic acid resin]
NW4032D: manufactured by Nature Works, melting point 160 ° C., L-form purity 98.6%
PLA-K: Cross-linked polylactic acid resin [plasticizer] prepared according to Production Example 1 of polylactic acid resin
(MeEO ₃ ) ₂ SA: Diester of succinic acid and triethylene glycol monomethyl ether prepared in Production Example 1 of plasticizer, average molecular weight 410
DOA: Bis (2-ethylhexyl) adipate (Dahachi Chemical Co., Ltd. DOA)
[Crystal nucleating agent]
PPA-Zn: unsubstituted phenylphosphonic acid zinc salt (manufactured by Nissan Chemical Industries, no melting point)
(Hydrolysis inhibitor)
Starvacol 1-LF: monocarbodiimide compound (Rhein Chemie)
〔filler〕
Amorphous cellulose A to E: Amorphous cellulose crystalline cellulose prepared according to Production Examples 1 to 5 of amorphous cellulose: “Theorus TG-101” (manufactured by Asahi Kasei Chemicals), cellulose I type crystallinity 82 %, Cellulose average particle size 30 μm, iron content 5 ppm or less glass fiber: “T-187 (3)” (manufactured by Nippon Electric Glass Co., Ltd.), average fiber diameter 12 μm, average fiber length 3 mm
Carbon fiber: “HTA-C6-S” (manufactured by Toho Tenax Co., Ltd.), average fiber diameter 7 μm, average fiber length 3 mm
(Shock absorber)
METABLEN S-2006: Core-shell type silicone acrylic rubber (Mitsubishi Rayon Co., Ltd.)
Kuraray 2140E: Acrylic thermoplastic resin (Kuraray, LA-2140E)

  As is apparent from the results of Tables 1 to 5, the molded bodies (Examples 1 to 18) of the polylactic acid resin composition of the present invention may contain amorphous cellulose having a crystallinity of less than 50%. It can be seen that by adding a specific amount of glass fiber and a rubber component, the strength and impact resistance can be improved, and the color tone is also excellent. Further, from Table 3, the effect is exhibited even when the type of amorphous cellulose is different, while Comparative Example 10 in which carbon fiber, which is the same inorganic filler, is blended in place of glass fiber has extremely high color tone. Since it is inferior, it is suggested that the specific combination of amorphous cellulose, glass fiber, and rubber component has an effect of being excellent in color tone in addition to improvement in strength and impact resistance.

  The polylactic acid resin composition of the present invention can be suitably used for various industrial applications such as household goods, household appliance parts, automobile parts and the like.

Claims (6)

A polylactic acid resin composition comprising a polylactic acid resin, cellulose having a crystallinity of less than 50%, glass fibers, and a rubber component, wherein the crystallinity is less than 50% with respect to 100 parts by weight of the polylactic acid resin. cellulose 5 to 350 parts by weight is from 1 to 25 parts by weight of glass fibers, the rubber component Ri 1 to 45 parts by weight der, and the weight ratio of the rubber component and the glass fiber (rubber component / glass fibers) 0 a .1～10, you containing polylactic acid polylactic acid resin is crosslinked, the polylactic acid resin composition.   The polylactic acid resin composition according to claim 1, wherein the total amount of the glass fiber and the rubber component is 2 to 50 parts by weight with respect to 100 parts by weight of the polylactic acid resin. Furthermore, the polylactic acid resin composition of Claim 1 or 2 containing a plasticizer. An ester in which the plasticizer has two or more ester groups in the molecule, and at least one alcohol component constituting the ester is added with an average of 0.5 to 5 moles of alkylene oxide having 2 to 3 carbon atoms per hydroxyl group The polylactic acid resin composition according to claim 3 , which is a compound. The polylactic acid resin molded object formed by shape | molding the polylactic acid resin composition in any one of Claims 1-4 . A method for producing a polylactic acid resin molded article, comprising: a step of melt-kneading the polylactic acid resin composition according to any one of claims 1 to 4 using a melt kneader; and a step of molding the composition using an injection molding machine.