JP5692786B2 - Method for producing polylactic acid resin composition - Google Patents

Description

  The present invention relates to a method for producing a polylactic acid resin composition. More specifically, a method for producing a polylactic acid resin composition that can be suitably used as daily miscellaneous goods, home appliance parts, automobile parts, electrical and electronic parts, and the like, and an injection-molded product of the polylactic acid resin composition obtained by the production method It relates to the manufacturing method.

  Among the biodegradable resins, polylactic acid resin is inexpensive because L-lactic acid, which is a raw material, is produced by fermentation using sugars extracted from corn, straw and the like, and since the raw material is derived from plants, Since the amount of carbon oxide emission is extremely small and the characteristics of the resin are its high rigidity and high transparency, its use is currently expected.

  However, in addition to the above properties, the polylactic acid resin has the property of lacking flexibility because it is brittle and hard. Moreover, since the crystallization speed is slow, the molded product obtained by general injection molding has an amorphous state, and the glass transition point (Tg) of the polylactic acid resin is as low as 60 ° C., so that the environment is about 55 ° C. or higher. It cannot be used below and has poor heat resistance.

  On the other hand, for example, in Patent Document 1, the main component polylactic acid resin, organic crystal nucleating agent 0.1 to 5% by mass, plasticizer 1 to 10% by mass, organic phosphorus compound 10 to 35% by mass, reaction By melt-kneading a raw material containing 0.01% by mass or more of the organic organophosphorus compound such that the melt flow rate at 190 ° C. and a load of 21.2 N is 5 g / 10 min or less, the moldability is improved by promoting crystallization. It is reported that heat resistance will be ensured. Specifically, in Example 1, melt kneading is performed under the conditions of a barrel temperature of 180 ° C., a screw rotation speed of 240 rpm, and a discharge rate of 15 kg / h.

  On the other hand, as biodegradable resin fillers, many attempts have been made to use naturally-derived organic materials such as wood powder, paper powder, bamboo powder, and kenaf. For example, in Patent Document 2, the chain length of a biodegradable polyester resin is extended with a specific carbodiimide compound to improve the strength of a molded product. In this case, cellulose fibers are blended and melt kneaded at 180 ° C. Is disclosed.

Further, in Patent Document 3, when an organic filler is melt-kneaded with a polylactic acid resin, it becomes difficult to obtain a stable color tone due to the burning of the natural organic filler, or a natural organic filler. Since the surface appearance of the molded product may be impaired due to the decomposition of bubbles and the generation of bubbles in the product, the color tone can be improved by melt-kneading the polylactic acid resin and the natural organic filler under specific conditions. It has been reported that a resin composition having excellent mechanical properties and heat resistance can be obtained. Specifically, polylactic acid resin and waste paper powder are melt-kneaded under the conditions of a resin temperature of 160 to 230 ° C., a residence time of 30 to 300 seconds, and a shear rate of 10 to 1500 seconds− ¹ . The shear rate is calculated from the cylinder diameter and rotation speed of the melt kneader and the minimum gap distance between the screw and the cylinder inner wall.

JP 2008-19294 A JP 2006-63111 A JP 2005-35134 A

  Durable materials such as home appliance parts and automobile parts are required to have a certain degree of flexibility in addition to excellent color tone and heat resistance and mechanical strength. However, since a resin molded body with higher strength is inferior in flexibility, a further polylactic acid resin molded body having both strength and flexibility is required.

  Moreover, since the naturally derived organic filler used conventionally is inferior in the dispersibility (fluidity) in a molding machine, it is necessary to raise injection pressure for shaping | molding. For this reason, excessive heat is applied to the polylactic acid resin composition that moves in the groove in the narrow molding machine, and the color tone of the resulting molded product is inferior.

  An object of the present invention is to provide a method for producing a polylactic acid resin composition that provides a molded article having excellent color tone and having both strength and flexibility, and a polylactic acid resin composition obtained by the production method. An object of the present invention is to provide a method for manufacturing an injection molded body.

  Accordingly, as a result of repeated investigations to solve the above problems, the present inventors have found that when cellulose is blended as a polylactic acid resin as an organic filler and melt-kneaded, the crystallinity of the cellulose is 50%. By using less than cellulose and performing melt-kneading under specific conditions, it is found that the resulting molded product of the polylactic acid resin composition has a good color tone and has both strength and flexibility. The present invention has been completed.

The present invention
[1] Melt kneading a raw material for a polylactic acid resin composition containing polylactic acid resin and cellulose having a crystallinity of less than 50% using a melt kneading apparatus having a kneading screw having a screw diameter of D (mm) A method for producing a polylactic acid resin composition comprising a step of obtaining a melt-kneaded product, wherein the melt-kneading is performed by setting the temperature of the melt-kneaded product to T (° C.) and the melt-kneaded product discharge amount of the melt-kneaded device. A polylactic acid resin composition comprising a step of satisfying the following formulas (1) and (2) when W (kg / h) and the rotation speed of the kneading screw are R (r / min): Manufacturing method,
170 ℃ ≦ T ≦ 220 ℃ (1)
0.15 ≦ (W × 100) / (D × R) ≦ 4.0 (2)
[2] A method for producing a polylactic acid resin composition molded body in which a polylactic acid resin composition obtained by the production method according to [1] is injection-molded by an injection molding machine, the method comprising: A process for producing a molded product of polylactic acid resin composition, including a step of injection molding within a temperature range of 170 to 200 ° C., and [3] a polylactic acid resin and a crystallinity of less than 50% A polylactic acid resin composition containing cellulose which is 180 ° C. and a melt flow rate (MFR) at a load of 2.16 kg of 1.0 to 12 g / 10 min, and the temperature of the resin composition is 170 to 200 ° C. It is related with the manufacturing method of the polylactic acid resin composition molded object including the process of injection-molding within the range.

  The polylactic acid resin composition obtained by the production method of the present invention has an excellent effect that it has an excellent color tone and can provide a molded article having both strength and flexibility. 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 method for producing a polylactic acid resin composition of the present invention includes a step of melt-kneading a raw material for a polylactic acid resin composition containing a polylactic acid resin and cellulose, and the cellulose has a crystallinity of less than 50%. And the melt kneading conditions are specific conditions. In a resin composition containing a polylactic acid resin, plant fibers such as cellulose may be used as a biodegradable reinforcing material instead of an inorganic filler. In such a resin composition, a resin molded body having high strength can be obtained by further increasing the crystallinity of cellulose having a crystallinity of about 80%. However, when cellulose having a high degree of crystallinity is blended with the polylactic acid resin, the flexibility of the resulting resin molded product is lowered, and the strength enhancing effect of cellulose cannot be sufficiently exhibited. In addition, since a resin with high strength is inferior in flexibility, a further polylactic acid resin molded body that satisfies both resin strength and flexibility is required. Thus, as a result of the study by the present inventors, surprisingly, a resin composition obtained by melt-kneading a raw material in which cellulose having a crystallinity of less than 50% is blended under specific conditions is obtained. It was found that the molded body of the present invention was excellent in flexibility while being excellent in strength. Although the detailed reason is unknown, in cellulose having a crystallinity of less than 50%, the proportion of strong hydrogen bonds in the molecule is reduced, and by adding moderate energy by melt-kneading, it is possible to form a polylactic acid resin. As the interaction increases, the cellulose in the melt-kneaded product can be uniformly dispersed without being decomposed. Furthermore, since the cellulose plays a role as a plasticizer, it is possible to achieve both strength and flexibility. Inferred. Furthermore, although the molded product of the present invention has excellent color tone, cellulose in the melt-kneaded product is uniformly dispersed without being decomposed in order to melt-knead cellulose having a crystallinity of less than 50% under specific conditions. This is thought to be possible. In this specification, “strength” means a property evaluated by “flexural modulus” described later, and “flexibility” means a property evaluated by “flexural strain rate” described later.

<Method for producing polylactic acid resin composition>
The production method of the present invention includes a step of melt-kneading a raw material for a polylactic acid resin composition containing a polylactic acid resin and cellulose having a crystallinity of less than 50%.

[Polylactic acid resin]
Polylactic acid resin is a polylactic acid obtained by polycondensation of only a lactic acid component as a raw material monomer and / or a polylactic acid obtained by polycondensation of a lactic acid component and a hydroxycarboxylic acid component as raw material monomers. contains.

  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 or both of the optical isomers may be contained, but from the viewpoint of moldability, lactic acid having high optical purity mainly containing any of the optical isomers is used. It is preferable. 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 viewpoint of compatibility between strength and flexibility of the polylactic acid resin composition molded article, 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 flexibility of the molded product of polylactic acid resin composition, heat resistance From the viewpoints of properties and transparency, D-lactide and L-lactide are preferred. 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 dimer of lactic acid is preferably 80 to 100 mol% and more preferably 90 to 100 mol% in the lactic acid component from the viewpoint of achieving both strength and flexibility of the polylactic acid resin composition molded body.

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

  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, polylactic acid comprising 85 mol% or more and less than 100 mol% of either L-lactic acid or D-lactic acid and more than 0 mol% and 15 mol% or less of the hydroxycarboxylic acid component is obtained. Among them, polylactic acid obtained by using lactide, which is a cyclic dimer of lactic acid, glycolide, which is a cyclic dimer of glycolic acid, and caprolactone, as raw material monomers is preferable.

  In the present invention, the polylactic acid is obtained by using a lactic acid component mainly composed of different isomers from the viewpoint of compatibility between strength and flexibility of the polylactic acid resin composition molded article, heat resistance, and transparency. Stereocomplex polylactic acid composed of the two types of polylactic acid obtained may be used.

  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.

  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.

  The polylactic acid resin can be synthesized by the above-mentioned method, but commercially available products include, for example, “Lacia series” such as Lacia H-100, H-280, H-400, and H-440 (Mitsui Chemicals). "Nature Works" (manufactured by Nature Works), Ecoplastic U'z S-09, S-12, S-17, etc., 3001D, 3051D, 3251D, 4032D, 4042D, 6201D, 6251D, 7000D, 7032D, etc. "Eco-plastic U'z series" (manufactured by Toyota Motor Corporation). Among these, Laissia H-100, H-280, H-400, H-440 (manufactured by Mitsui Chemicals) from the viewpoints of both the strength and flexibility of the polylactic acid resin composition molded body and the heat resistance. 3001D, 3051D, 3251D, 4032D, 4042D, 6201D, 6251D, 7000D, 7032D (manufactured by Nature Works), Ecoplastic U'z S-09, S-12, S-17 (manufactured by Toyota Motor Corporation) are preferable.

  In the present invention, other biodegradable resins may be contained in addition to the polylactic acid resin. Other biodegradable resins include polyhydroxybutyrate, polycaprolactone, polybutylene succinate, polybutylene succinate / adipate, polyethylene succinate, polymalic acid, polyglycolic acid, polydioxanone, poly (2-oxetanone), etc. Aliphatic polyester resins; aliphatic aromatic copolyester resins such as polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polytetramethylene adipate / terephthalate; starch, cellulose, chitin, chitosan, gluten, gelatin, zein, soy protein Polyesters having biodegradability such as mixtures of natural polymers such as collagen and keratin with the above aliphatic polyester resins or aliphatic aromatic copolyester resins, and the like. That. The content of the polylactic acid resin is not particularly limited, but it is included in the raw material for the polylactic acid resin composition from the viewpoint of compatibility between strength and flexibility of the molded body of the polylactic acid resin composition, heat resistance, and productivity. In the total resin, 50% by weight or more is preferable, 80% by weight or more is more preferable, and 90% by weight or more is more preferable.

  The content of the polylactic acid resin is preferably 50% by weight or more, more preferably 60% by weight or more, and further preferably 70% by weight or more in the raw material for the polylactic acid resin composition.

[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 crystal form of natural cellulose. Cellulose type I crystallinity is also related to the physical and chemical properties of cellulose. The higher the value, the higher the hardness, density, etc. However, 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, from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition molded body. 20% or less is more preferable, 10% or less is more preferable, and it is further more preferable that it is substantially 0% in which a type I crystal is not detected in 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 molded product of a polylactic acid resin composition 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.

Recycled pulp and recycled paper can be produced by deinking by using a deinking agent or by removing ink and ash from the raw waste paper by deashing treatment. The deinking treatment is roughly classified into a washing method and a flotation method, but the flotation method is preferable from the viewpoint of obtaining a polylactic acid resin composition molded body with less coloring. The deinking agent is not particularly limited and a known one can be used. From the viewpoint of deinking and deashing performance, polyoxyethylene alkyl ether, alcohol or phenolic compound with ethylene oxide, Nonionic surfactants to which alkylene oxides such as propylene oxide and butylene oxide are added are preferred, and nonionic surfactants to which alkylene oxides are added to alcohols from the viewpoint of both the strength and flexibility of the molded product of polylactic acid resin composition Is more preferable, and the compound represented by the following general formula (B) is more preferable.
_{R 1 -O- (C x H 2x} O) l (AO) m (C y H 2y O) n -H (B)
[Where,
R ₁ : Residue obtained by removing a hydroxyl group from a monohydric alcohol having 8 to 24 carbon atoms or an alkylphenol having a linear or branched alkyl group or alkenyl group having 6 to 16 carbon atoms AO: carbon number containing an ethylene oxide group as an essential component 1 to 2 or more alkylene oxide groups of 2 to 4 are groups or groups arranged randomly or x, y: 3 or 4, respectively, which may be the same or different l: 1 ≦ l ≦ 300
m: 50 <m ≦ 300
n: 1 ≦ n ≦ 300
Means

  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 pulps, recycled paper, etc. as a cellulose-containing raw material, from the viewpoint of improving the impact resistance of the polylactic acid resin composition molded article, the amount of lignin in the cellulose-containing raw material is preferably 15% by weight or less, More preferably, it is 10% by weight or less, and further preferably 8% by weight or less. The structural unit of lignin is not particularly limited and may be a known unit. From the viewpoint of improving the impact resistance of the biodegradable resin molded article, guaiacyl type, syringyl type, p-hydroxy A phenyl type is desirable.

  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.

  Examples of the alkali cooking (also simply referred to as cooking) include a soda method or a kraft method.

  The soda method is a method for removing lignin using an alkaline agent such as sodium hydroxide, potassium hydroxide, or sodium carbonate.

  The kraft method is a method for removing lignin by sharing an alkaline agent such as sodium hydroxide, potassium hydroxide, or sodium carbonate with a chemical containing a sulfur element such as sodium sulfide or sodium sulfite.

  The addition amount of the alkaline agent is preferably 5 to 40% by weight of the dry weight of the cellulose-containing raw material used for cooking.

  In addition, the alkali cooking can use a quinone cooking aid, oxygen, hydrogen peroxide, and polysulfide as additives in addition to the alkali chemicals. These additives can be used according to the nature and amount of the lignin contained, but may not be used when digestion can be performed with only an alkaline agent. When adding, 10 weight% or less of the cellulose containing raw material weight used for cooking is preferable.

  The cellulose-containing raw material to be subjected to alkali cooking may be pulverized in advance or cut and crushed into chips in order to facilitate the cooking. The concentration of the cellulose-containing raw material in the cooking mixture during alkali cooking is 5 to 50% by weight, the reaction temperature is preferably 100 to 200 ° C, more preferably 140 to 200 ° C, and the heating time is desirably 60 to 500 minutes. The conditions can be changed according to the shape and size of the chip and the nature and amount of the lignin contained.

  Also, when using recycled pulp, recycled paper, etc. as the cellulose-containing raw material, the ash content of the cellulose-containing raw material from the viewpoints of both the crystallinity of the polylactic acid resin and the strength and flexibility of the molded product of the polylactic acid resin composition Is preferably 35% by weight or less, more preferably 20% by weight or less, and still more preferably 10% by weight or less. In addition, in this specification, the ash content of a cellulose containing raw material can be measured by the method as described in the below-mentioned Example.

  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. In addition, 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, or from the viewpoint of durability of the polylactic acid resin composition molded body The cellulose-containing raw material whose water content is adjusted may be subjected to pulverization.

(Method for preparing cellulose-containing raw material with adjusted bulk density and average particle size)
The method for adjusting the bulk density and average particle size of the cellulose-containing raw material is not particularly limited, but a method of pulverizing by applying a compressive shear force is preferable from the viewpoint of destroying the crystal structure of cellulose and pulverizing. 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 make the cellulose-containing raw material amorphous is called 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 using a cutting machine such as a shredder, a rotary cutter, or a slitter cutter. When a rotary cutter is used, the size of the obtained chip-like cellulose-containing raw material can be controlled by changing the opening of the screen (sieving). The opening of the screen is preferably 1 to 50 mm, more preferably 1 to 30 mm. If the opening of the screen is 1 mm or more, the cellulose-containing raw material does not become flocculent, and the handleability is improved because the cellulose-containing raw material has an appropriate bulkiness as a cellulose-containing raw material used for the subsequent primary pulverization. If the opening of the screen is 50 mm or less, the load can be reduced in the primary pulverization because it has an appropriate size as a cellulose-containing raw material used for the subsequent primary pulverization.

  Moreover, when using a sheet-like cellulose containing raw material, it is preferable to use a shredder or a slitter cutter, and it is more preferable to use a slitter cutter from a viewpoint of productivity.

  In a slitter cutter, a sheet-like cellulose-containing raw material is vertically cut along a longitudinal direction of the sheet with a roll cutter to form an elongated strip, and then along the width direction of the sheet with a fixed blade and a rotary blade. By crossing short, a rectangular parallelepiped cellulose-containing raw material can be easily obtained. As the slitter cutter, a sheet pelletizer manufactured by Horai can be preferably used. When this apparatus is used, a sheet-like cellulose-containing raw material can be roughly pulverized to about 1 to 20 mm square.

  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 extruder may be either a single-screw type or a twin-screw type, but a twin-screw extruder is preferable from the viewpoint of increasing the conveyance capability.

  The twin screw extruder is an extruder in which two screws are rotatably inserted into a cylinder, and a conventionally known one can be used. The rotation directions of the two screws may be the same or opposite directions, but the rotation in the same direction is preferable from the viewpoint of increasing the conveyance capability. The screw engagement conditions may be any of full-engagement, partial meshing, and non-meshing extruders. However, from the viewpoint of improving the processing capability, the complete meshing type and the partial meshing type are preferable.

  As an extruder, it is preferable to provide what is called a kneading disk part in any part of a screw from a viewpoint of applying a strong compressive shear force.

  The kneading disc part is composed of a plurality of kneading discs, which are combined continuously and shifted in a constant phase, for example by 90 °, with a narrow gap as the screw rotates. An extremely strong shearing force can be imparted by forcibly passing the cellulose-containing raw material. As a configuration of the screw, it is preferable that the kneading disk portion and the plurality of screw segments are alternately arranged. In the case of a twin screw extruder, it is preferable that the two screws have the same configuration.

As a treatment method, a method in which a cellulose-containing raw material, preferably the chip-like cellulose-containing raw material is charged into an extruder and continuously processed is preferable. The shear rate is preferably 10 sec ^-1 or more, more preferably 20～30000Sec ^-1, more preferably 50~3000sec ^-1. If the shear rate is 10 sec ⁻¹ or more, the bulk density is effectively increased. Other treatment conditions are not particularly limited, and the treatment temperature is preferably 5 to 200 ° C.

  Moreover, as the number of passes by the extruder, a sufficient effect can be obtained even with one pass, but from the viewpoint of increasing the bulk density of the cellulose-containing raw material, it is preferable to carry out two passes or more when one pass is insufficient. . Further, from the viewpoint of productivity, 1 to 10 passes is preferable. By repeating the pass, coarse particles are pulverized and a powdery cellulose-containing raw material with little variation in particle size can be obtained. When performing two or more passes, in consideration of production capacity, a plurality of extruders may be arranged in series for processing.

  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 handling property 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 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. In addition, the average particle diameter of the cellulose containing raw material after a primary grinding | pulverization can be measured by the method as described in the below-mentioned Example. 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. The drying process can be either a batch process or a continuous process.

  In the above-described drying method, a known dryer can be appropriately selected and used. For example, “Introduction to Powder Engineering” (Edited by Japan Powder Industry Technical Association, Powder Engineering Information Center, 1995) 176 Examples include the dryer described on the page. You may use a dryer 1 type or in combination of 2 or more types.

  The temperature in the drying treatment cannot be determined unconditionally depending on the drying means, drying time, etc., but is preferably 10 to 250 ° C, more preferably 50 to 150 ° C, and further preferably 60 to 120 ° C. As processing time, 0.01-2 hr is preferable and 0.02-1 hr is more preferable. If necessary, the drying treatment may be performed under reduced pressure, and the pressure is preferably 1 to 120 kPa, more preferably 50 to 105 kPa.

  Moreover, it is preferable to coarsely pulverize the cellulose-containing raw material into a chip shape or a rectangular parallelepiped shape before the drying treatment. The size of the coarsely pulverized cellulose-containing raw material is preferably 1 to 50 mm square, more preferably 1 to 30 mm square in the case of a chip. In the case of a rectangular parallelepiped shape, it is preferably 1 to 20 mm square. By roughly pulverizing to the above size, the drying treatment and the secondary pulverization can be efficiently and easily performed. In addition, as a rough pulverization method, the method similar to the rough pulverization process performed before the primary pulverization of a cellulose containing raw material is mentioned.

  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.

  Therefore, the moisture content of the dried cellulose-containing raw material in the present invention is preferably 4.5% by weight or less, more preferably 4.3% by weight or less, further preferably 4.0% by weight or less, and 3.5% by weight or less. Is more preferable, and 3.0% by weight or less is even more preferable. When the water content is 4.5% by weight or less, secondary pulverization can be easily performed, and it is preferable from the viewpoint of durability of the molded body of the polylactic acid resin composition. On the other hand, the lower limit of the water content is preferably 0.2% by weight or more, more preferably 0.3% by weight or more, and further preferably 0.4% by weight or more from the viewpoint of productivity and drying efficiency of secondary grinding. Preferably, 0.6% by weight or more is even more preferable. From the above viewpoint, the moisture content of the dried cellulose-containing raw material subjected to secondary pulverization is preferably 0.2 to 4.3% by weight, more preferably 0.3 to 4.0% by weight, 3.5 weight% is further more preferable, and 0.6 to 3.0 weight% is still more preferable.

  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 diameter 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. In addition, the average particle diameter of the cellulose-containing raw material whose water content has been adjusted can be measured by the method described in Examples described later.

  Next, the cellulose-containing raw material obtained by the primary pulverization or the drying treatment is subjected to secondary pulverization in order to make it amorphous.

  As a pulverizer used for secondary pulverization (hereinafter also referred to as pulverizer A), 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 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 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 A 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, still more 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.

  The rod filling rate varies depending on the model of the container-driven crusher, but is preferably in the range of 10 to 70%, more preferably 15 to 60%. When the filling rate is within this range, the contact frequency between the cellulose-containing raw material and the rod is improved, and the grinding efficiency can be improved. Here, the filling rate refers to the apparent volume of the rod relative to the volume of the stirring unit of the container-driven crusher. 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.

  When the pulverizer A is a stirred tank pulverizer and the medium is a ball, the outer diameter of the ball is preferably 0.1 to 100 mm, more preferably 0.5 to 50 mm. . If the size of the ball 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 pieces of the ball and the like. it can.

  The filling rate of the balls varies depending on the type of the stirring tank type pulverizer, but is preferably in the range of 10 to 97%, more preferably 15 to 95%. When the filling rate is within this range, the contact frequency between the cellulose-containing raw material and the ball is improved, and the grinding efficiency can be improved without hindering the movement of the medium. Here, the filling rate means the apparent volume of the ball with respect to the volume of the stirring unit of the stirring tank type pulverizer.

  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 coexistence of strength and flexibility of the polylactic acid resin composition molded article, and handleability, it is an 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 coexistence of the intensity | strength and flexibility of a polylactic acid resin composition molded object, 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. 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 flexibility and impact resistance while maintaining the strength of the polylactic acid resin composition molded article, the cellulose used for melt kneading has a crystallinity of less than 50%. It is preferable that it is obtained by reducing the particle size of the cellulose having a mean particle size of 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. Therefore, the cellulose having a crystallinity of less than 50% contained in the polylactic acid resin composition in the present invention is converted into the cellulose obtained by the mechanical treatment, that is, the cellulose obtained by treating with the pulverizer A. Furthermore, it is preferable to be obtained by adding a grinding aid and grinding.

  The pulverizer (hereinafter also referred to as pulverizer B) used for the tertiary pulverization is preferably a medium pulverizer, and is exemplified by the same pulverizer (pulverizer A) suitable for secondary pulverization. Note that the pulverizer A and the pulverizer B 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 examples thereof include balls, rods, tubes, etc. From the viewpoint of cellulose atomization efficiency, the grinder B is preferably a vibration mill filled with rods.

  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. The filling rate of the rod is the same as described above.

  As the grinding aid used for the tertiary grinding, alcohol, aliphatic amide, aromatic carboxylic acid amide, rosinic acid amide, fatty acid metal from the viewpoint of promoting adsorption to cellulose by interaction with hydroxyl groups in cellulose. Salts, metal salts of aromatic sulfonic acid dialkyl esters, metal salts of phenylphosphonic acid, metal salts of phosphoric acid esters, metal salts of rosin acids, fatty acid esters, carbohydrazides, N-substituted ureas, salts of melamine compounds, Examples include uracils and polyethers. Among them, from the viewpoint of the thermal stability of the molded product 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. From the viewpoint of improving the pulverization efficiency of cellulose and the impact resistance of the molded product of polylactic acid resin composition, alcohol, aliphatic amide, metal salt of fatty acid, phenyl At least one selected from the group consisting of metal phosphonates, fatty acid esters and polyethers is more preferred.

  The alcohol used for the grinding aid is preferably 5 to 40 carbon atoms, more preferably 10 to 30 carbon atoms, still more preferably 14 to 22 carbon atoms from the viewpoint of suppressing aggregation of cellulose and reducing the average particle size. Linear or branched alcohols are preferred. In addition, from the viewpoint of interaction with a hydroxyl group in cellulose for promoting adsorption to cellulose, an aldehyde group, a carbonyl group, an amino group, an amide group, an imino group, an imide group, a cyano group, a thiol group, You may have substituents, such as an ester group and an ether group.

  Examples of the alcohol include lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, cetostearyl alcohol, 2-octyldodecanol, and the like. Among them, cellulose pulverization efficiency and impact resistance of the polylactic acid resin composition molded article From the viewpoint of improving the properties, myristyl alcohol, stearyl alcohol, behenyl alcohol and the like are preferable.

  As the aliphatic amide used for the grinding aid, from the viewpoint of interaction with a hydroxyl group in cellulose for promoting adsorption to cellulose, an aldehyde group, a carbonyl group, an amino group, an imino group in the aliphatic amide, You may have substituents, such as an imide group, a cyano group, a thiol group, an ester group, and an ether group.

  Specific examples of the aliphatic amide compound include 12-hydroxystearic acid monoethanolamide, ethylenebislauric acid amide, ethylenebiscapric acid amide, ethylenebiscaprylic acid amide, methylenebis12-hydroxystearic acid amide, ethylenebis12. -Hydroxystearic acid amide, hexamethylene bis 12-hydroxystearic acid amide, etc. Among them, methylene bis 12-hydroxystearic acid is preferred from the viewpoint of improving the grinding efficiency of cellulose and the impact resistance of the polylactic acid resin composition molded article. Preferred are alkylene bishydroxy fatty acid amides such as amide, ethylene bis 12-hydroxystearic acid amide, hexamethylene bis 12-hydroxystearic acid amide, Phosphoric acid amides are more preferred.

  The fatty acid metal salt used in the grinding aid is preferably a fatty acid metal salt having 12 to 24 carbon atoms, more preferably 14 to 20 carbon atoms, from the viewpoint of suppressing aggregation of cellulose and reducing the average particle size. . In addition, from the viewpoint of interaction with a hydroxyl group in cellulose to promote adsorption to cellulose, aldehyde group, carbonyl group, amino group, amide group, imino group, imide group, cyano group, thiol group, You may have substituents, such as an ester group and an ether group.

  Examples of the fatty acid metal salts include sodium salts such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, potassium salts, calcium salts, magnesium salts, etc. From the viewpoint of improving the impact resistance of the molded product of the polylactic acid resin composition, sodium myristate and sodium stearate are preferable.

The phenylphosphonic acid metal salt used for the grinding aid is a phenylphosphonic acid metal salt having a phenyl group and a phosphone group [—PO (OH) ₂ ] which may have a substituent, and the phenyl group substituent. Examples thereof include an alkyl group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms in an alkoxy group, and the like. 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 the metal salt of phenylphosphonic acid include salts of lithium, sodium, magnesium, aluminum, potassium, calcium, barium, copper, zinc, iron, cobalt, nickel, etc., and impact resistance of the polylactic acid resin composition molded article From the viewpoint of improving the quality, a zinc salt is preferable.

As fatty acid esters used for the grinding aid, compounds represented by the following general formula (1) are preferred.
R ¹ COOR ² (1)
In the formula, R ¹ and R ² are not particularly limited, but R ¹ preferably has 1 to 50 carbon atoms, more preferably 1 to 50 carbon atoms from the viewpoint of improving the impact resistance of the polylactic acid resin composition molded article. 40, more preferably 2-30 linear or branched alkyl group, alkenyl group, hydroxyalkyl group or alkyl ether group, R ² preferably has 1 to 50 carbon atoms, more preferably 1 to 30 carbon atoms. More preferably, an alkyl group containing 2 to 20 alkyl groups, an alkenyl group, an ether group, an alkyl ether group and a hydroxyl group, a residue obtained by removing one acyloxy group from glyceride, or an alkyleneoxy group is preferable.

  In addition, from the viewpoint of interaction with hydroxyl groups in cellulose to promote adsorption to cellulose, aldehyde groups, carbonyl groups, amino groups, amide groups, imino groups, imide groups, cyano groups, thiol groups in fatty acid esters And may have a substituent such as an ether group.

  Examples of the fatty acid esters include isopropyl myristate, octyldodecyl myristate, octyl palmitate, stearyl stearate, sorbitan monooleate, sorbitan monostearate, pentaerythritol monooleate, pentaerythritol monostearate, polyoxyethylene sorbitan tristearate Rate, 12-hydroxystearic acid triglyceride, 12-hydroxystearic acid diglyceride, 12-hydroxystearic acid monoglyceride, pentaerythritol-mono-12-hydroxystearate, pentaerythritol-di-12-hydroxystearate, pentaerythritol-tri- 12-hydroxystearate or succinic acid and triethylene glycol monomethyl ether Examples thereof include ester compounds. Among them, 12-hydroxystearic acid triglyceride, pentaerythritol monostearate, pentaerythritol mono-12 from the viewpoint of improving the pulverization efficiency of cellulose and the impact resistance of the molded product of the polylactic acid resin composition. At least one selected from the group consisting of -hydroxystearate, pentaerythritol-di-12-hydroxystearate, pentaerythritol-tri-12-hydroxystearate or an ester compound of succinic acid and triethylene glycol monomethyl ether is preferred More preferred are pentaerythritol monostearate and ester compounds of succinic acid and triethylene glycol monomethyl ether.

As the polyether used for the grinding aid, a compound represented by the following general formula (2) is preferable.
R ³ —O — [(R ⁴ O) _p —H] (2)
In the formula, R ³ , R ⁴ and p are not particularly limited, but R ³ is a hydrogen atom or an alkyl group having 1 to 50 carbon atoms from the viewpoint of improving the impact resistance of the polylactic acid resin composition molded article. Alternatively, an alkenyl group is preferable, and R ⁴ is preferably an alkylene group having 2 to 4 carbon atoms, and more preferably an ethylene group or a propylene group. Moreover, p shows an average added mole number, Preferably it is the number of 2-400, More preferably, it is the number of 5-200, More preferably, the number of 5-150 is good.

As a specific example of the compound of the general formula (2), a compound represented by the following general formula (3) is preferable from the viewpoint of improving the pulverization efficiency of cellulose and the impact resistance of the polylactic acid resin composition molded article.
^{_{R 5 -O- (C 2 H 4}} O) s (C 3 H 6 O) t -H (3)
In the formula, R ⁵ represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms, and s and t represent average addition mole numbers of ethylene oxide (EO) and propylene oxide (PO), respectively, Preferably it is a number from 0 to 200, more preferably a number from 2 to 100 (however, s = 0 and t = 0), and when both EO and PO are included, it is a random or block adduct It may be.

Examples of the alkyl group in R ⁵ include methyl group, ethyl group, isopropyl group, propyl group, butyl group, t-butyl group, isobutyl group, various pentyl groups, various hexyl groups, various octyl groups, various decyl groups, and various dodecyl groups. , Various tetradecyl groups, various hexadecyl groups, various octadecyl groups, and the like. R ⁵ is preferably a hydrogen atom or an alkyl group having 1 to 18 carbon atoms from the viewpoint of improving the pulverization efficiency of cellulose and the impact resistance of the molded product of the polylactic acid resin composition.

  The weight average molecular weight of the polyether used in the present invention is preferably in the range of 100 to 20000, more preferably in the range of 400 to 20000. The weight average molecular weight is measured by a GPC method using chloroform as a solvent and polystyrene as a standard substance.

  Moreover, in this invention, in the range which does not impair the effect of this invention, other grinding | pulverization adjuvant other than the said grinding | pulverization adjuvant can be used. Other grinding aids include aromatic carboxylic acid amides such as trimesic acid tris (t-butylamide), m-xylylene bis 12-hydroxystearic acid amide, 1,3,5-benzenetricarboxylic acid tricyclohexylamide; p-xylyl Rosin acid amides such as lenbisrosinic acid amide; metal salts of aromatic sulfonic acid dialkyl esters such as dimethyl dibarium 5-sulfoisophthalate and dimethyl dicalcium 5-sulfoisophthalate; sodium-2,2′-methylenebis (4 , 6-di-t-butylphenyl) phosphate, metal salts of phosphate esters such as aluminum bis (2,2′-methylenebis-4,6-di-t-butylphenylphosphate); such as potassium methyldehydroabietic acid Metal salts of rosin acids; decamethylene dicarbonyl di Carbohydrazide such as emissions benzoyl hydrazide; N- substituted ureas such as xylene-bis-stearyl urea; salts of melamine compounds such as melamine cyanurate; uracils of 6-methyl uracil, and the like.

  The above grinding aids may be used alone or in combination of two or more in any ratio.

  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 the present invention, from the viewpoint of further improving the flexibility of the polylactic acid resin composition molded article, cellulose having a crystallinity of less than 50% obtained by the secondary pulverization, the secondary pulverization and The surface of cellulose obtained through the third pulverization and having a crystallinity of less than 50% and an average particle size of 30 μm or less is treated 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 cellulose to be surface-treated from the viewpoint of compatibility between the strength and flexibility of the polylactic acid resin composition molded body, 0.3-3 weight part is more preferable, and 0.5-2 weight part is further more 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 preferably 1 part by weight or more from the viewpoint of obtaining an appropriate bending strength and bending elastic modulus with respect to 100 parts by weight of the polylactic acid resin. From the viewpoint that the bending elastic modulus does not become too high, 350 parts by weight or less is preferable. Moreover, from a viewpoint of the flexibility of a polylactic acid resin composition molded object and impact resistance, 1-300 weight part is preferable, 5-100 weight part is more preferable, and 5-50 weight part is further more preferable. That is, from the viewpoint of obtaining the flexural strength, flexural modulus, flexibility and impact resistance of the molded product of polylactic acid resin composition, the content of cellulose having a crystallinity of less than 50% is 100 parts by weight of polylactic acid resin. The amount is preferably 1 to 300 parts by weight, more preferably 5 to 100 parts by weight, and still more preferably 5 to 50 parts by weight. In the present specification, “content” means “content”, “use amount” or “blending amount”.

  In the present invention, in addition to the polylactic acid resin and cellulose having a crystallinity of less than 50%, plasticizers, organic crystal nucleating agents, hydrolysis inhibitors, and the like may be used as appropriate.

[Plasticizer]
Cellulose having a crystallinity of less than 50% used in the present invention has a markedly reduced crystallinity compared to cellulose used in conventional resin compositions. Therefore, it plays the role of a plasticizer by itself, but from the viewpoint of further improving the strength and flexibility of the polylactic acid resin composition molded article and impact resistance, molding the polylactic acid resin composition in the present invention. The body preferably contains 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, monobutyl itaconate Polyesters such as acid esters, oleates such as butyl oleate, diacetyl caprylic acid monoglyceride, diacetyl lauric acid monoglyceride, ricinoleic acid monoglyceride, decaglycerin monoelate, tricresyl Phosphate esters such as sulfate, polyethylene glycol (hereinafter PEG), PEG diacetate, polypropylene glycol (hereinafter PPG), PEG-PPG-PEG block polymer, polyalkylene glycols such as PPG-PEG-PPG block polymer, triethylene glycol Lactic acid oligomer esters such as monomethyl ether lactic acid oligomer ester and rosin acid esters such as diethylene glycol rosin ester acetate can be used. Among these, from the viewpoint of improving the flexibility of the molded product of the polylactic acid resin composition, carboxylic acid esters and / or phosphate esters are preferable, and among them, the strength and flexibility of the molded product of the polylactic acid resin composition are compatible. From the viewpoint of the above, an average of 0.5 to 5 mol of an alkylene oxide having 2 or more ester groups in the molecule and at least one alcohol component constituting the ester having 2 to 3 carbon atoms per hydroxyl group was added. It is preferable to contain an ester compound (hereinafter referred to as “AO addition ester compound”).

The carboxylic acid ester is preferably an oligoester represented by the following formula (I) from the viewpoint of improving volatility and moldability.
R ⁶ O—CO—R ⁷ —CO — [(OR ⁸ ) _a —CO—R ⁸ —CO—] _b R ⁷ (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 ⁷ may be the same or different, and all R ⁸ may be the same or different.

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.

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 preferable, an ethylene group is more preferable, and an ethylene group and a 1,4-butylene group are preferable, and an ethylene group is more preferable from the viewpoints of developing a plasticizing effect and economical 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 biodegradable 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, succinic acid or adipic acid and polyethylene glycol are specifically used from the viewpoint of compatibility between strength and flexibility of the molded product of polylactic acid resin composition, moldability, plasticity, and bleed resistance of the plasticizer. At least one selected from the group consisting of an ester compound with monomethyl ether and an ester compound with acetic acid and glycerin or ethylene glycol ethylene oxide adduct is preferred, and an ester compound of succinic acid or adipic acid with polyethylene glycol monomethyl ether is More preferred.

  From the viewpoint of volatility resistance, 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-added ester compound is preferably 250 to 700, more preferably from the viewpoint of compatibility between strength and flexibility of the polylactic acid resin composition molded article, bleed resistance and volatilization resistance of the plasticizer. Is 300 to 600, more preferably 350 to 550, and still more preferably 400 to 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 compatibility with the polylactic acid resin and the cellulose having a crystallinity of less than 50% is good. 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 molded body 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 or more in the plasticizer from the viewpoint of compatibility between strength and flexibility of the molded product of the polylactic acid resin composition and bleed resistance of the plasticizer. 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 obtaining both the strength and flexibility of the molded product of the polylactic acid resin composition and impact resistance. 7-30 weight part is more preferable, 8-30 weight part is further more preferable, and 8-20 weight part is still more preferable.

[Crystal nucleating agent]
The crystal nucleating agent is disclosed in JP 2008-115372 A, from the viewpoint of compatibility between the strength and flexibility of the molded product of the polylactic acid resin composition, moldability, heat resistance, impact resistance, and bloom resistance of the crystal nucleating agent. Or 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, as described in JP-A-2008-174718, and at least one of these It is more preferable to use a phenylphosphonic acid metal salt in combination, and it is more preferable to use a compound having a hydroxyl group and an amide group in the molecule and a phenylphosphonic acid metal salt in combination.

  As a compound having a hydroxyl group and an amide group in the molecule, two or more hydroxyl groups are used from the viewpoint of improving compatibility with the polylactic acid resin and achieving both the strength and flexibility of the molded product of the polylactic acid resin composition. And a fatty acid bisamide having two or more amide groups, and methylene bis 12-hydroxystearic acid from the viewpoint of moldability, heat resistance, impact resistance and bloom resistance of the crystal nucleating agent of the polylactic acid resin composition More preferred are alkylene bishydroxystearic amides such as amides, ethylene bis 12-hydroxystearic amides, hexamethylene bis 12-hydroxystearic amides, and even more preferred are ethylene bis 12-hydroxystearic amides.

  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 crystal nucleating agent during kneading and improving the crystallization rate of the polylactic acid resin composition. 70-220 degreeC is more preferable and 80-190 degreeC is still 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. 12-hydroxystearic acid triglyceride is preferable from the viewpoints of compatibility between strength and flexibility of the molded body of the polylactic acid resin composition, moldability, heat resistance, impact resistance, and bloom resistance of the crystal nucleating agent.

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 the metal salt of phenylphosphonic acid include salts of lithium, sodium, magnesium, aluminum, potassium, calcium, barium, copper, zinc, iron, cobalt, nickel, etc., and impact resistance of the polylactic acid resin composition molded article From the viewpoint of improving the quality, a zinc salt is preferable.

  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% by weight with respect to 100 parts by weight of the polylactic acid resin from the viewpoint of obtaining both the strength and flexibility of the molded product of the polylactic acid resin composition and impact resistance. Part, preferably 0.10 to 3 parts by weight, more preferably 0.20 to 2 parts by weight, and still more preferably 0.20 to 1 part by weight.

[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 compatibility between strength and flexibility of a polylactic acid resin composition molded product, and moldability, From the viewpoints of heat resistance, impact resistance of the polylactic acid resin composition molded body, and 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 compound may be used alone or in combination of two or more in order to satisfy the moldability, heat resistance, impact resistance and bloom resistance of the hydrolysis inhibitor of the polylactic acid resin composition molded body. 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 moldability of the polylactic acid resin composition molded body. Is more preferable, and 0.20 to 1 part by weight is even more preferable.

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

  Furthermore, in the present invention, as other components than the above, an antistatic agent, an antifogging agent, a light stabilizer, an ultraviolet absorber, a pigment, an antifungal agent, an antibacterial agent, a foaming agent, etc. It can be used as long as it is not impaired.

  In the present invention, the raw material for the polylactic acid resin composition containing these components is melt-kneaded using a melt-kneading apparatus. As a method of supplying the raw material to the melt-kneading apparatus, each raw material is directly supplied individually. Any method can be used, such as a method, a method in which all the raw materials are mixed in advance and then fed together, or a method in which the raw materials are aggregated (granulated) using a high speed mixer such as a Henschel mixer. Among these, from the viewpoint of achieving both strength and flexibility of the molded body of the polylactic acid resin composition, a method of directly supplying each raw material individually and a method of supplying all raw materials in a lump after premixing them are preferable. Moreover, it is preferable to supply a raw material using a weight feeder from a viewpoint of supply stability.

  The melt kneader is not particularly limited as long as it has a kneading screw having a screw diameter of D (mm), and is a single screw extruder, a twin screw extruder, a multi screw extruder, or a combination thereof. Further, known ones such as an extruder such as a twin-screw / single-screw composite type extruder, a Banbury mixer, a kneader, and a mixing roll can be used. From the standpoint of compatibility between strength and flexibility of the molded product of the polylactic acid resin composition, it is preferable to use a twin-screw extruder, a twin-screw / single-screw composite extruder, and a twin-screw extrusion. More preferred. The screw diameter [D (mm)] means the maximum diameter when the screw has a cross section perpendicular to the longitudinal direction, and melt kneading that satisfies the conditions described later can be performed. The screw diameter [D (mm)] is preferably 10 to 100 mm, preferably 20 to 70 mm, from the viewpoint of dispersibility of cellulose having a crystallinity of less than 50% and coloring of the resulting molded product. Is more preferable.

  The twin screw extruder is an extruder in which two screws are rotatably inserted into a cylinder, and is not particularly limited. The rotation direction of the two screws may be the same or opposite directions, but the rotation in the same direction is preferable from the viewpoint of enhancing the dispersibility of cellulose having a crystallinity of less than 50% in the resin.

  As the meshing condition of the screw, meshing type and non-meshing type are used, but the meshing type is preferable from the viewpoint of enhancing the dispersibility of cellulose having a crystallinity of less than 50% in the resin.

  Depending on the shape of the parts, the screw has a kneading part (so-called kneading disk part) whose main function is melting and kneading raw materials and a conveying part (so-called screw segment) whose main function is conveying raw materials or melt-kneaded products. Have.

  The kneading disc part is composed of a plurality of kneading discs, which are combined continuously and shifted in a constant phase, for example by 90 °, with a narrow gap as the screw rotates. An extremely strong shearing force can be imparted by forcibly passing the raw material for the polylactic acid resin composition or the melt-kneaded material. Therefore, it is preferable that the screw of the melt-kneading apparatus used in the present invention has two or more kneading disk parts from the viewpoint of achieving both the strength and flexibility of the molded polylactic acid resin composition.

  As the arrangement of the kneading disk portion and the screw segment, it is preferable that the kneading disk portion and the plurality of screw segments are alternately arranged. In addition, it is preferable that the two screws of the twin screw extruder have the same configuration.

  The rotational speed [R (r / min)] of the screw is preferably 10 to 600 r / min, and preferably 50 to 450 r / min, from the viewpoint of dispersibility of cellulose having a crystallinity of less than 50% and coloring of the obtained molded product. Is more preferable, and 70 to 200 r / min is more preferable.

  The screw rotates to discharge the melt-kneaded polylactic acid resin composition from a die at the tip of the twin screw extruder. The discharge amount [W (kg / h)] of the melt-kneaded product is preferably from 3 to 500 kg / h, more preferably from 5 to 300 kg / h, from the viewpoint of both the strength and flexibility of the polylactic acid resin composition. 7 to 250 kg / h is more preferable. The discharge amount can be measured according to the method described in Examples described later.

  The ratio (W / R) of the discharge amount [W (kg / h)] and the rotational speed of the screw [R (r / min)] is from the viewpoint of coexistence of the strength and flexibility of the polylactic acid resin composition. 0.01 ≦ W / R ≦ 2.0 is preferable, 0.03 ≦ W / R ≦ 1.9 is more preferable, and 0.05 ≦ W / R ≦ 1.8 is more preferable.

In the present invention, from the viewpoint of achieving both the strength and flexibility of the polylactic acid resin composition and obtaining a stable color tone of the polylactic acid resin composition molded article, the discharge amount [W (kg / h)] , Screw diameter [D (mm)], screw rotation speed [R (r / min) is the following relational expression (2):
0.15 ≦ (W × 100) / (D × R) ≦ 4.0 (2)
The filling,
Preferably, 0.17 ≦ (W × 100) / (D × R) ≦ 3.8
More preferably, 0.18 ≦ (W × 100) / (D × R) ≦ 3.7
It is. When the ratio [(W × 100) / (D × R)] is 0.15 or more, the dispersion state of cellulose in the polylactic acid resin composition becomes good, and both strength and flexibility can be achieved, When the ratio is 4.0 or less, cellulose is not decomposed by kneading and the color of the polylactic acid resin composition molded article is improved.

  The number of barrels to be coupled is not particularly limited, but is preferably coupled at least for each kneading disk portion and screw segment.

  Although the set temperature of the barrel is not particularly limited, in the present invention, from the viewpoint of producing a polylactic acid resin composition having both strength and flexibility and an excellent color tone, the temperature of the melt-kneaded product [resin temperature, T (° C.)] is 170 ° C. ≦ T ≦ 220 ° C., preferably 170 ° C. ≦ T ≦ 220 ° C., more preferably 170 ° C. ≦ T ≦ 220 ° C. What is necessary is just to adjust the temperature of each barrel so that it may become in the said temperature range. Accordingly, the set temperature of the barrel is preferably equal to or higher than the melting point (Tm) (° C.) of the polylactic acid resin, more preferably Tm to Tm + 100 (° C.), and further preferably Tm to Tm + 50 (° C.). Specifically, it is preferably 170 to 220 ° C, more preferably 170 to 210 ° C, and further preferably 170 to 200 ° C. It is preferable that the temperature of each barrel can be individually set. The temperature of each barrel is not particularly limited as long as it is within the above range, but it is preferable that the temperatures of all the barrels are the same. In the present specification, the set temperature of the melt-kneading apparatus means a temperature obtained by averaging the temperatures of the barrels. Moreover, the temperature of a melt-kneaded material can be measured according to the method as described in the below-mentioned Example.

  Commercial products of the extruder used in the present invention include KTK type twin screw extruder (manufactured by Kobe Steel Co., Ltd.), TEM type twin screw extruder (manufactured by Toshiba Machine Co., Ltd.) and PCM type twin screw extruder (Ikegai Iron Works). And TEX type twin screw extruder (Nippon Steel Works), etc., among them, PCM type twin screw extruder (Ikegai Iron Works), TEX type twin screw extruder (Nippon Steel) (Made by a company) is preferable.

  In the present invention, melt kneading is performed using such a melt kneading apparatus. From the viewpoint of achieving both strength and flexibility of the polylactic acid resin composition molded article, introduction of an inert gas such as nitrogen, or reduced pressure conditions It is preferable to melt-knead under.

  In the present invention, the polylactic acid resin composition discharged from the die is formed into a strand. From the viewpoint of operability at the time of subsequent injection molding, the strand is cut with a strand cutter to be pelletized, or from the die. It may be pelletized using a cutting means such as a hot cutter or an underwater cutter at the same time as it is discharged.

  In addition, when cutting a strand with a strand cutter and pelletizing, in order to make the intensity | strength of the melt-kneaded material obtained higher, a strand is preferably 15-40 degreeC after melt-kneading, More preferably, 20-40 degreeC More preferably, it is preferably kept in a liquid medium at 25 to 30 ° C., preferably 0.5 to 10 seconds, more preferably 1 to 10 seconds. Examples of the liquid medium include low-viscosity liquids having a boiling point of 100 ° C. or higher, such as water, ethylene glycol, and silicone oil, and water is preferable from the viewpoint of safety and handling properties. The temperature of the liquid medium can be stably maintained by circulating it with a temperature control device.

  Thus, a polylactic acid resin composition is obtained by the production method of the present invention.

  The obtained polylactic acid resin composition is made by using polylactic acid resin and cellulose having a crystallinity of less than 50% as a raw material, and melt-kneaded under the above-mentioned conditions. It has a very high melt flow rate (MFR). For this reason, when the polylactic acid resin composition is filled in a mold by injection and molded, the fluidity of the polylactic acid resin composition is excellent, so there is no need to apply excessive pressure, and the resulting molded article There is no loss of color. From the viewpoint of the color of the polylactic acid resin composition molded article, the MFR of the polylactic acid resin composition is preferably 1.0 to 12 g / 10 min, more preferably 1.0 to 10.0 g / 10 min, and 1.0 to 8. 0 g / 10 min is more preferable. In the present invention, the melt flow rate (MFR) is a value at 180 ° C. and a load of 2.16 kg.

  Moreover, the obtained polylactic acid resin composition can prepare a molded object through the process of injection molding of filling and shape | molding in a metal mold | die by injection, for example. Therefore, this invention also provides the polylactic acid resin composition molded object obtained by the manufacturing method of this invention.

  A preferred method for producing the molded product of the polylactic acid resin composition of the present invention may include a step of injection-molding the polylactic acid resin composition obtained by the production method of the present invention with an injection molding machine. The temperature of the obtained polylactic acid resin composition is preferably 170 to 200 ° C., more preferably 170 to 190, from the viewpoint of both the strength and flexibility of the resin composition and the color of the polylactic acid resin composition molded product. It is preferable to include a step of injection molding within a temperature range of ℃, more preferably 170 to 185 ℃. The injection molding machine is not particularly limited as long as the temperature can be set.

  The mold temperature at the time of molding is preferably 10 to 90 ° C, more preferably 20 to 85 ° C, and further preferably 50 to 85 ° C, from the viewpoint of improving the crystallization speed of the polylactic acid resin composition.

  Thus, a polylactic acid resin composition molded article can be obtained by the production method of the present invention, but has good color tone and excellent strength and flexibility, so that it can be used for daily miscellaneous goods, home appliance parts, automobile parts, electrical and electronic parts. Etc., and can be suitably used.

[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 cellulose-containing raw material with adjusted water content]
A sieve having an opening of X μm and 0.9 X μm is prepared, and 50 g of a sample is placed on the sieve and sieved. At that time, when the weight of the cellulose remaining on the sieve without passing through the sieve with an opening of X μm and not passing through the sieve with an opening of 0.9 X μm is 90% by weight (45 g) or more, the average of the cellulose-containing raw materials The particle size is X μm.

[Average particle size of cellulose-containing raw material, amorphous cellulose and crystalline cellulose obtained by primary grinding]
The average particle size of the cellulose-containing raw material, amorphous cellulose and crystalline cellulose obtained by the primary pulverization means a volume median particle size (D ₅₀ ), and is a laser diffraction / scattering type particle size distribution measuring device. Measurement is performed using “LA-920” (manufactured by Horiba, Ltd.). The measurement conditions are that ultrasonic treatment is performed for 1 minute before the particle size measurement, water 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.

[Ash content of cellulose-containing raw materials]
The ash content is determined from the weight of the residue by weighing 2.0 g of a cellulose-containing raw material in a crucible, using an electric furnace (ADVANTEC, KM-600), firing at 500 ° C. for 2 hours.

[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

[Melting point of crystal nucleating agent]
The melting point is measured by increasing the temperature from 20 ° C. to 500 ° C. at a temperature increase rate of 10 ° C./min using a DSC apparatus (Perkin Elmer, Diamond DSC).

[Temperature of melt-kneaded product]
The temperature of the melt-kneaded product at the outlet portion of the melt-kneader is measured three times using a center thermometer (SN-350II) manufactured by Therken Co., Ltd., and the average value is taken as the melt-kneaded product temperature.

[Temperature of resin composition in injection molding machine]
The temperature of the resin composition at the outlet portion of the injection molding machine is measured three times at 10-minute intervals using a thermometer (SN-350II) manufactured by Thermoken, and the average value is taken as the resin composition temperature. .

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.

Production Example 2 of Plasticizer (Triester Compound with Ethylene Oxide Adduct obtained by Adding 3 Mole of Ethylene Oxide to Acetic Acid and Glycerin)
An autoclave was charged with a specified amount of 3 moles of ethylene oxide to 1 mole of concentrated glycerin for cosmetics manufactured by Kao Co., Ltd., and a constant pressure of 0.3 MPa was added using 1 mole% of KOH as a catalyst until the pressure became constant. After reacting at 0 ° C., the mixture was cooled to 80 ° C. to obtain a catalyst-unneutralized product. KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) as an adsorbent for the catalyst was added to the product 8 times the catalyst weight, and an adsorption treatment was performed at 80 ° C. for 1 hour under slight nitrogen pressure. Further, the liquid after the treatment was No. The adsorbent was filtered with a Nutse pre-coated with Radiolite # 900 on filter paper No. 2 to obtain a 3 mol glycerin ethylene oxide adduct (hereinafter referred to as POE (3) glycerin). This was charged into a four-necked flask, heated to 105 ° C. and stirred at 300 r / min, and acetic anhydride was added dropwise at a ratio of 3.6 mol per mol of POE (3) glycerin in about 1 hour. And reacted. After dropping, the mixture was aged at 110 ° C. for 2 hours and further aged at 120 ° C. for 1 hour. After aging, unreacted acetic anhydride and by-product acetic acid were topped under reduced pressure and further steamed to obtain POE (3) glycerin triacetate.

Production example 3 of plasticizer (oligoester of succinic acid and diethylene glycol)
In a four-necked flask (with a stirrer, thermometer, dropping funnel, distillation tube, nitrogen blowing tube) 999 g (9.41 mol) of diethylene glycol and 23.6 g of 28% sodium methoxide-containing methanol solution (sodium methoxide 0.122) After adding methanol and distilling methanol with stirring at 120 ° C. for 0.5 hours at normal pressure (101.3 kPa), 4125 g (28.2 mol) of dimethyl succinate (manufactured by Wako Pure Chemical Industries, Ltd.) was added. Methanol produced by the reaction was distilled at the same time while adding dropwise over the course of the reaction, followed by distillation of methanol at a pressure of 50 to 760 mmHg and 75 ° C., and then a methanol solution 4 containing 28% sodium methoxide. .4 g (sodium methoxide 0.023 mol) was added, pressure 22-760 mmHg, methanol at 100 ° C. After adding 41 g of KYOWARD 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) and stirring for 1 hour at a pressure of 30 mmHg and 80 ° C., the filtrate was filtered under reduced pressure, and the filtrate was filtered at a pressure of 2 mmHg and 70 to 190 ° C. Upon heating, unreacted dimethyl succinate was distilled off to obtain a yellow liquid.

Plasticizer Production Example 4 (Tris (ethoxyethoxyethyl) phosphate)
To a 1 liter four-necked flask, 600 g (4.47 mol) of diethylene glycol monoethyl ether was added and stirred under reduced pressure (20 kPa) while blowing dry nitrogen gas at a flow rate of 50 mL per minute. Next, 114 g (0.745 mol) of phosphorus oxychloride was slowly added dropwise while maintaining the reaction system at room temperature (15 ° C.), and then aged at 40 to 60 ° C. for 5 hours. Thereafter, 149 g of a 16% by weight aqueous sodium hydroxide solution was added for neutralization, excess unreacted diethylene glycol monoethyl ether was distilled off under reduced pressure at a temperature of 70 to 120 ° C., and contacted with water vapor to obtain crude phosphoric acid. 367 g of triester was obtained. Further, 300 g of a 16% by weight aqueous sodium chloride solution was added to the crude phosphoric acid triester for washing. Thereafter, the phase-separated lower phase was drained, and the remaining upper phase was dehydrated under reduced pressure at 75 ° C., and the solid content was further removed by filtration to obtain 266 g of the desired tris (ethoxyethoxyethyl) phosphate ( Yield 80%). This tris (ethoxyethoxyethyl) phosphate is a colorless and transparent uniform liquid. As a result of the chloro ion analysis, the chloro ion content was 10 mg / kg or less.

  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”. Tables 1 to 5 show the average particle diameter and crystallinity of the amorphous cellulose obtained by Examples. As the crystalline cellulose, Theolas TG-101 (cellulose type I crystallinity 82%, cellulose average particle size 30 μm) manufactured by Asahi Kasei Chemicals Corporation was used.

Production Example 1 of Amorphous Cellulose
[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% by weight (content in the remaining components excluding water from the cellulose-containing raw material) The same applies hereinafter), cellulose I type crystallinity 81%, moisture content 7.0% by weight, bulk density 200 kg / m ³ ) was applied to a shredder (“MSX2000-IVP440F”, manufactured by Meiko Shoji Co., Ltd.) and about 10 mm × 5 mm × 1.5 mm chip pulp was used.

[Primary grinding (extruder processing)]
The obtained chip-like pulp is put into a twin screw extruder (Suehiro EPM, “EA-20”) at 2 kg / hr, and cooling water is allowed to flow from outside at a shear rate of 660 sec ⁻¹ and a screw rotation speed of 300 r / min. However, one pass processing was performed. The twin-screw extruder is a fully meshing type co-rotating twin-screw extruder, and the screws arranged in two rows are combined with a screw portion having a screw diameter of 40 mm and 12 blocks alternately (90 °). The two screws have the same configuration. The temperature of the twin screw extruder was 30 to 70 ° C. due to heat generated by the treatment. The pulp obtained after the extruder treatment (after primary pulverization) had a bulk density of 219 kg / m ³ and an average particle size of 120 μm.

[Secondary grinding (pulverizer processing)]
The pulp obtained after the extruder treatment was used as a crusher A as a batch-type agitation tank type pulverizer (“Sand Grinder” manufactured by Igarashi Machinery Co., Ltd.): Container volume 800 mL, filled with 720 g of 5 mmΦ zirconia beads, filling rate 25%, stirring blade diameter 70 g). While cooling water was passed through the container jacket, pulverization was performed for 180 minutes at a stirring speed of 2000 r / min. The temperature during operation was in the range of 30-70 ° C.

  After completion of the treatment, no fixed pulp or the like was found on the wall surface or bottom of the stirring tank type pulverizer. The pulp obtained after the secondary pulverization treatment was taken out of the stirred tank pulverizer, passed through a sieve having an opening of 75 μm, and 45 g (90% by weight of the input amount) of amorphous cellulose A was obtained as an undersieved product.

Production Example 2 of Amorphous Cellulose
50 g of pulp obtained after the extruder treatment (after primary pulverization) in the same manner as in Production Example 1 was used as a pulverizer used for secondary pulverization as a vibration mill (“MB-1”, manufactured by Chuo Kako Co., Ltd.) The capacity is 3.5 L), and 11 rods (cross-sectional shape: circular, diameter: 30 mm, length: 218 mm, material: stainless steel) are filled into a vibration mill (filling rate 48%), amplitude is 8 mm, rotation speed The treatment was performed for 60 minutes at 1200 rpm. The temperature during operation was 30 ° C.

  After completion of the treatment, no fixed pulp or the like was found on the wall or bottom of the vibration mill. The pulp obtained after the secondary pulverization treatment was taken out from the vibration mill, passed through a sieve having an opening of 75 μm, and 30 g (60% by weight of the input amount) of amorphous cellulose B was obtained as a sieved product.

Production Example 3 of Amorphous Cellulose
[Primary grinding (extruder processing)]
As a cellulose-containing raw material, pine chips (comfort soft bed made by Doggyman Hayashi Co., Ltd., cellulose content 66% by weight, cellulose I-type crystallinity 72%, moisture content 7.2% by weight, bulk density 160 kg / m ³ ) are used. In the same manner as in Production Example 1, primary pulverization was performed. The cellulose-containing raw material obtained after the extruder treatment (after primary pulverization) had a bulk density of 225 kg / m ³ and an average particle size of 105 μm.

[Secondary grinding (pulverizer processing)]
The same pulverizer as in Production Example 2 was used as the pulverizer (pulverizer A) used for secondary pulverization of 50 g of the cellulose-containing raw material obtained after the extruder treatment (after primary pulverization). The treatment was performed under conditions for 75 minutes. The temperature during operation was 30 ° C.

  After the treatment was completed, no chips or the like were found on the wall or bottom of the pulverizer. The chip obtained after the secondary pulverization treatment was taken out from the pulverizer, passed through a sieve having an opening of 75 μm, and 43 g (85% by weight of the charged amount) of amorphous cellulose C was obtained as an under-sieved product.

Production Example 4 of Amorphous Cellulose
[Coarse grinding]
As a cellulose-containing raw material, the same pulp as used in Production Example 1 is applied to a sheet pelletizer (“SG (E) -220” manufactured by Horai Co., Ltd.), and roughly pulverized to a size of about 4 mm × 4 mm × 1.5 mm. did.

[Drying treatment]
Using a shelf dryer (ADVANTEC vacuum constant temperature dryer “DRV320DA”), the pulp content obtained by the coarse pulverization treatment is set to 0.8 wt% after drying. Dried.

[Secondary grinding]
50 g of pulp obtained by the drying treatment was treated for 40 minutes (secondary grinding treatment) under the same conditions as in Production Example 2 using the same grinding machine as in Production Example 2 as a grinding machine used for secondary grinding. . The temperature during operation was 30 ° C.

  After completion of the treatment, no fixed pulp or the like was found on the wall or bottom of the pulverizer. The obtained secondary pulverized product was taken out from the pulverizer, passed through a sieve having an opening of 75 μm, and 42.5 g (85% by weight of the charged amount) of amorphous cellulose D was obtained.

Production Example 5 of Amorphous Cellulose
[Coarse grinding]
As a cellulose-containing raw material, deinked pulp (manufactured by Kokumitsu Co., Ltd., cellulose content 92% by weight, cellulose I-type crystallinity 80%, moisture content 7.7% by weight, bulk density 223 kg / m ³ ) It was subjected to the same shredder and coarsely pulverized to a size of about 10 mm × 5 mm × 2.0 mm.

[Drying treatment]
The pulp obtained by the coarse pulverization treatment was dried using the same shelf dryer as in Production Example 4 so that the moisture content of the dried pulp was 1.0% by weight.

[Secondary grinding]
50 g of the pulp obtained by the drying treatment was treated for 45 minutes (secondary grinding treatment) under the same conditions as in Production Example 2 using the same grinding machine as in Production Example 2 as a grinding machine used for secondary grinding. . The temperature during operation was 30 ° C.

  After completion of the treatment, no fixed pulp or the like was found on the wall or bottom of the pulverizer. The obtained secondary pulverized product was taken out from the pulverizer and passed through a sieve having an opening of 75 μm to obtain 40 g (80% by weight of the charged amount) of amorphous cellulose E.

Production Example 6 of Amorphous Cellulose
In Production Example 1, amorphous cellulose F was obtained in the same manner as in Production Example 1 except that the processing time for secondary pulverization was changed from 180 minutes to 45 minutes.

Production Example 7 of Amorphous Cellulose
In Production Example 1, amorphous cellulose G was obtained in the same manner as in Production Example 1 except that the processing time for secondary pulverization was changed from 180 minutes to 90 minutes.

Production Example 8 of Amorphous Cellulose
[Third grinding (pulverizer processing)]
50 g of amorphous cellulose D and 5 g of PE-MS (pentaerythritol monostearate, manufactured by Kao Corporation, “Exepearl PE-MS”) as a grinding aid are mixed, and the whole amount of the mixture is used as a grinding machine B as a vibration mill. (Made by Chuo Kako Co., Ltd., “MB-1”, container total capacity 3.5L), 11 rods (cross-sectional shape: circular, outer diameter: 30 mm, length: 218 mm, material: stainless steel) vibration mill Amorphous cellulose H was obtained by pulverizing for 15 minutes under conditions of an amplitude of 8 mm and a rotational speed of 1200 revolutions / minute.

Production Example 9 of Amorphous Cellulose
Amorphous cellulose was produced in the same manner as in Production Example 8 except that the type of grinding aid was changed to PPA-Zn (unsubstituted phenylphosphonic acid zinc salt, “PPA-Zn” manufactured by Nissan Chemical Industries, Ltd.). I was obtained.

Production Example 10 of Amorphous Cellulose
Amorphous cellulose J was obtained in the same manner as in Production Example 8, except that the type of grinding aid was changed to stearyl alcohol (Kalco 8098, manufactured by Kao Corporation).

Production Example 11 of Amorphous Cellulose
Amorphous cellulose K was obtained in the same manner as in Production Example 8, except that the type of grinding aid was changed to sodium stearate (Lunac S-98, manufactured by Kao Corporation).

Production Example 12 of Amorphous Cellulose
Except that the type of grinding aid was changed to (MeEO ₃ ) ₂ SA (diester of succinic acid and triethylene glycol monomethyl ether, prepared by the above-mentioned plasticizer Production Example 1), Production Example 8 and In the same manner, amorphous cellulose L was obtained.

Production Example 13 of Amorphous Cellulose
Amorphous cellulose M was obtained in the same manner as in Production Example 8, except that the type of grinding aid was changed to OHC18EB (ethylenebis12-hydroxystearic acid amide, Nippon Kasei Co., Ltd., “Sripacs H”). .

Production Example 14 of Amorphous Cellulose
[Coarse grinding]
As a cellulose-containing raw material, a magazine (“MORE” manufactured by Shueisha, 297 mm × 210 mm × 0.5 mm, crystallinity 81%, cellulose content 60% by weight, moisture content 7.7% by weight, bulk density 200 kg / m ³ , ash content (Content 32.6% by weight) was subjected to a shredder (“MSX2000-IVP440F” manufactured by Meiko Trading Co., Ltd.) and coarsely pulverized to a size of about 10 mm × 5 mm × 0.5 mm.

[Drying treatment]
The magazine pieces obtained by the coarse pulverization treatment were dried using the same shelf dryer as in Production Example 4 so that the moisture content after drying was 0.7% by weight.

[Secondary grinding]
Using a pulverizer similar to Production Example 2 as a pulverizer used for secondary pulverization, 50 g of magazine pieces obtained by the drying treatment were treated for 40 minutes (secondary pulverization treatment) under the same conditions as in Production Example 2. It was. The temperature during operation was 30 ° C.

  After the treatment, no magazine sticking material was found on the wall or bottom of the grinder. The obtained secondary pulverized product was taken out from the pulverizer and passed through a sieve having an opening of 75 μm to obtain 42 g (84% by weight of the charged amount) of amorphous cellulose N.

Production Example 15 of Amorphous Cellulose
[Deinking (Deinking / Deashing)]
As a cellulose-containing raw material, a magazine (“MORE” manufactured by Shueisha, 297 mm × 210 mm × 0.5 mm, crystallinity 81%, cellulose content 60% by weight, moisture content 7.7% by weight, bulk density 200 kg / m ³ , ash content After cutting a shredder (made by Meiko Trading Co., Ltd., “M400”) into a size of about 20 mm × 50 mm × 0.5 mm, a certain amount thereof was put into a desktop disintegrator and placed at 50 ° C. Hot water, 0.2% by weight of caustic soda (vs. raw paper), and deinking agent (alcohol alkylene oxide adduct: DI-7250, manufactured by Kao) 0.1% by weight (vs. raw paper), used paper concentration 5 A weight percent solution was prepared, and then disaggregated for 15 minutes at a temperature of 50 ° C. to make waste paper into a pulp slurry, which was dewatered to a pulp concentration of 18 wt. 0.6% by weight of soda (waste paper), 2.2% by weight of sodium silicate (waste paper), 30% -3.5% by weight of hydrogen peroxide (waste paper) and deinking agent (DI-7250) , Manufactured by Kao Co., Ltd.) 0.2% by weight (vs. raw paper), adjusted to a pulp concentration of 15% by weight, mixed again with a desktop disintegrator for 1 minute, and aged at 120 ° C. for 120 minutes. Thereafter, water was added to dilute the pulp concentration to 4% by weight, and the pulp was further disaggregated for 3 minutes with a desktop disintegrator, then the warm water was added to adjust the pulp concentration to 1% by weight, and the temperature was adjusted to 30 ° C. for 10 minutes. Rotation treatment was performed to perform deinking and deashing treatment to obtain a pulp slurry having a predetermined ash content.The obtained pulp slurry was concentrated to a pulp concentration of 6% by weight with a mesh wire (# 80), and then water was added. In addition, the pulp concentration is diluted to 1% by weight. It was prepared pulp sheet by PPI sheet machine (ash content 15.9 wt%).

  Except for using the obtained deinking-treated pulp sheet, similarly to Production Example 14, coarse pulverization treatment, drying treatment, and secondary pulverization were sequentially performed to obtain amorphous cellulose O.

Production Example 16 of Amorphous Cellulose
In the deinking process, the amorphous cellulose P was produced in the same manner as in Production Example 15 except that the flotation treatment time was changed to 20 minutes and a pulp sheet having an ash content of 6.0% by weight was prepared and used. Got.

Production Examples 17-22 of Amorphous Cellulose
The silane coupling agent of the kind and quantity shown in Table 5 is added to 100 parts by weight of amorphous cellulose shown in Table 5 and mixed using a Henschel mixer (FM-10B, manufactured by Mitsui Miike Chemical Co., Ltd.). Then, surface treatment was performed to obtain amorphous celluloses Q to V.

Examples 1-46 and Comparative Examples 1-11
As raw materials, polylactic acid resin, plasticizer, crystal nucleating agent, hydrolysis inhibitor, and filler (amorphous cellulose or crystalline cellulose) shown in Tables 6 to 12 are used, and these are shown in Tables 6 to 12. Using a melt-kneading apparatus, melt-kneading was performed under the conditions shown in Tables 6 to 12, and strand cutting was performed to obtain polylactic acid resin composition pellets. The obtained pellets were dried at 70 ° C. under reduced pressure for 1 day, and the water content was adjusted to 1% by weight or less. In addition, the discharge amount is obtained by receiving the resin composition after melt-kneading on a tray having a known weight and performing the operation of measuring the weight after 10 minutes three times, and the discharge amount per hour (kg / h) from the average value. Asked.

  The obtained pellets were filled into a cylinder set to the temperature shown in Tables 6 to 12 and injection-molded, and a test piece [rectangular columnar test piece (125 mm × 12 mm × 6 mm]] was obtained at a mold temperature of 80 ° C. and a molding time of 10 minutes. And the characteristics were examined according to the following methods of Test Examples 1 and 2. The results are shown in Tables 6 to 12.

<Test Example 1> [Color tone]
For the prismatic test piece (125 mm × 12 mm × 6 mm)], the YI (Yellow Index) value of the molded product was measured using a spectroscopic colorimeter (SE2000 manufactured by Nippon Denshoku Industries Co., Ltd.).

<Test Example 2> [Strength (flexural modulus), flexibility (bending fracture strain rate)]
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. The bending elastic modulus and bending fracture strain rate were determined. In either case, the higher the value, the better the strength and flexibility. In addition, about the bending fracture | rupture distortion rate, what did not fracture | rupture by applying the load within a measurement range was set as the fracture | rupture not.

In addition, the raw materials and apparatuses in Tables 6 to 12 are as follows.
[Polylactic acid resin]
NW4032D: manufactured by Nature Works, melting point 160 ° C., L-form purity 98.6%
NW3001D: manufactured by Nature Works, melting point 160 ° C., L-form purity 98.6%
NW3251D: manufactured by Nature Works, melting point 160 ° C., L-form purity 98.6%
[Plasticizer]
(MeEO ₃ ) ₂ SA: Diester of succinic acid and triethylene glycol monomethyl ether prepared in Production Example 1 of plasticizer, average molecular weight 410
(AcEO) ₃ Gly: Triester compound of acetic acid prepared from Production Example 2 of plasticizer and ethylene oxide adduct obtained by adding 3 mol of ethylene oxide to glycerin, average molecular weight 350
DAIFACTY-101: Diester of adipic acid and diethylene glycol monomethyl ether / benzyl alcohol = 1/1 mixture (manufactured by Daihachi Chemical Industry Co., Ltd.), average molecular weight 338
MeSA-DEG (b = 1.5): Oligoester of succinic acid and diethylene glycol prepared from Production Example 3 of plasticizer (b = 1.5 in formula (I)), average molecular weight 430
TEP: Tris (ethoxyethoxyethyl) phosphate prepared from Production Example 4 of plasticizer, average molecular weight 447
Riquemar PL-019: Glycerin diacetomono (caprylic acid / capric acid) ester (manufactured by Riken Vitamin Co., Ltd.)
ATBC: Acetyl tri-n-butyl citrate (J-Plus)
DOA: Dioctyl adipate (Wako Pure Chemical Industries, Reagent)
[Crystal nucleating agent]
OHC18EB: Ethylene bis 12-hydroxystearic acid amide (Nippon Kasei Co., Ltd., SLIPAX H, melting point 145 ° C.)
PPA-Zn: unsubstituted phenylphosphonic acid zinc salt (manufactured by Nissan Chemical Industries, no melting point)
(Hydrolysis inhibitor)
PCI: Polycarbodiimide compound (Nisshinbo Co., Ltd., Carbodilite LA-1)
[Melt-kneading equipment]
A-1: Meshing type twin screw extruder (manufactured by Nippon Steel Works, TEX28V, screw diameter 28 mm)
A-2: Meshing type twin screw extruder (manufactured by Nippon Steel Works, TEX44αII, screw diameter 44 mm)
A-3: Different direction rotating conical twin screw extruder (Toshiba Machine Co., Ltd., TEC-67, screw diameter 67 mm)

  As is clear from the results of Tables 6 to 12, the polylactic acid resin injection-molded articles (Examples 1 to 46) obtained by the production method of the present invention are higher in bending than molded articles having the same composition except for the filler. The elastic modulus and bending fracture strain rate are shown, and the color tone is also good. Thus, it is suggested that even when amorphous cellulose having a crystallinity of less than 50% is contained, both strength and flexibility can be achieved. Moreover, it turns out that the molded object obtained using this melt-kneaded material has a favorable color tone when the melt-kneaded material temperature in the case of preparing a melt-kneaded material exists in the range of 170-220 degreeC.

  The polylactic acid resin composition obtained by the production method of the present invention can be suitably used for various industrial uses such as daily goods, household appliance parts, automobile parts and the like.

Claims (3)

A raw material for a polylactic acid resin composition containing polylactic acid resin and cellulose having a crystallinity of less than 50% is melt-kneaded and melted using a melt-kneader having a screw for kneading with a screw diameter of D (mm). A method for producing a polylactic acid resin composition comprising a step of obtaining a kneaded product, wherein the melt kneading is carried out by setting the temperature of the melt kneaded product to T (° C.) and the discharge amount of the melt kneaded product from the melt kneading apparatus to W (kg). / H), when the number of rotations of the kneading screw is R (r / min), the step of satisfying the following formulas (1) and (2) is included, and the crystallinity is Cellulose containing less than 50% contains cellulose having a crystallinity of 50% or more, a cellulose-containing raw material having a bulk density of 100 to 500 kg / m ³ and an average particle size of 0.01 to 1.0 mm, And water was removed from the raw material The method for producing a cellulose content in the remaining component of the slip is a cellulose-containing raw material is 20 wt% or more, is obtained by treatment with a pulverizer, polylactic acid resin composition.
170 ℃ ≦ T ≦ 220 ℃ (1)
0.15 ≦ (W × 100) / (D × R) ≦ 4.0 (2) A raw material for a polylactic acid resin composition containing polylactic acid resin and cellulose having a crystallinity of less than 50% is melt-kneaded and melted using a melt-kneader having a screw for kneading with a screw diameter of D (mm). A method for producing a polylactic acid resin composition comprising a step of obtaining a kneaded product, wherein the melt kneading is carried out by setting the temperature of the melt kneaded product to T (° C.) and the discharge amount of the melt kneaded product from the melt kneading apparatus to W (kg). / H), when the number of rotations of the kneading screw is R (r / min), the step of satisfying the following formulas (1) and (2) is included, and the crystallinity is Cellulose that is less than 50% is a cellulose-containing raw material containing cellulose having a crystallinity of 50% or more and an average particle size of more than 1.0 mm and not more than 50 mm, and having a moisture content of 4.5% by weight or less When water is removed from the raw material The method for producing the cellulose content in the components of the remainder of the cellulose-containing raw material is 20 wt% or more, is obtained by treatment with a pulverizer, polylactic acid resin composition.
170 ℃ ≦ T ≦ 220 ℃ (1)
0.15 ≦ (W × 100) / (D × R) ≦ 4.0 (2)   A method for producing a polylactic acid resin composition formed by injection-molding a polylactic acid resin composition obtained by the production method according to claim 1 or 2 using an injection molding machine, wherein the polylactic acid is disposed at an outlet of the injection molding apparatus. The manufacturing method of a polylactic acid resin composition molded object including the process of injection-molding within the range from which the temperature of a resin composition will be 170-200 degreeC.