JP2007154147A - Biodegradable resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable resin composition which is good in moldability and is excellent in heat resistance and impact resistance, and to provide a method for manufacturing a biodegradable resin molded article obtained by using this biodegradable resin composition. <P>SOLUTION: The biodegradable resin composition, containing a biodegradable resin, a plasticizer, an organic nucleating agent and an inorganic nucleating agent, is characterized in that the plasticizer is a compound having two or more of ester groups in its molecule and having an average mole number for ethylene oxide addition of 3-9, and the organic nucleating agent is a compound having a hydroxy group and an amide group in its molecule. The method for manufacturing a biodegradable resin molded article comprises (1) a process of mixing the biodegradable resin composition at a temperature higher than the melting point (Tm) of the biodegradable resin, and (2) a process of heat-treating the mixture at a temperature from a glass transition temperature (Tg) of the biodegradable resin composition to lower than Tm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biodegradable resin composition and a method for producing a biodegradable resin molded body using the biodegradable resin composition.

  General-purpose resins made from petroleum such as polypropylene and polyvinyl chloride are used in various fields such as daily goods, household appliances, automobile parts, building materials, and food packaging because of their good processability and durability. in use. However, these resin products have a disadvantage of good durability at the stage of finishing and discarding their functions, and are inferior in degradability in nature, and thus may affect the ecosystem.

  In order to solve such problems, thermoplastic resins and biodegradable resins include polylactic acid and copolymers of lactic acid and other aliphatic hydroxycarboxylic acids, aliphatic polyhydric alcohols and aliphatic polycarboxylic acids. Biodegradable resin compositions such as aliphatic polyesters derived from have been developed.

  Among these biodegradable resin compositions, polylactic acid resin is made of sugar from corn, straw, etc., and L-lactic acid has been made in large quantities by fermentation. Since the amount of discharged resin is extremely small, and the performance of the obtained resin is strong and transparent, it is expected to be used at present, and it is expected to be used in the field of agricultural civil engineering materials such as flat yarn, nets, seedling pots, windows, etc. Used in envelopes, shopping bags, compost bags, stationery, miscellaneous goods, etc. However, in the case of polylactic acid resin, it is fragile, hard, and lacks flexibility, so all are limited to the field of hard molded products. When molded into a film, it becomes inflexible or whitens when bent. The current situation is that it is not widely spread in the soft or semi-rigid field.

  Various methods for adding a plasticizer have been proposed as techniques for applying polylactic acid resin to soft and semi-rigid fields. For example, a technique of adding a plasticizer such as tributyl acetylcitrate or diglycerin tetraacetate is disclosed. When these plasticizers are added to polylactic acid and a film or sheet is formed by extrusion or the like, good flexibility is obtained, but because the resin is in an amorphous state, flexibility due to temperature changes near the glass transition point is obtained. The property changes markedly (temperature sensitivity) and the heat resistance at high temperatures is insufficient, so that the physical properties change significantly depending on the season, making it difficult to use in a high temperature environment. In order to solve this problem, a method of improving the heat resistance and the like by crystallizing polylactic acid by adding a crystal nucleating agent such as talc (Patent Document 1) has been proposed. However, when a large amount of a crystal nucleating agent such as talc is added, the transparency of the sheet or film after thermoforming is lowered, and there is a problem that the plasticizer bleeds when the molded product is left under high temperature and high humidity.

Patent Document 2 discloses an aliphatic polyester having a weight average molecular weight of 100,000 or more and a residual monomer amount of 5000 ppm or less, a low molecular compound having an amide group, talc, a carbodiimide compound, an isocyanate compound, and an oxazoline. An aliphatic polyester composition comprising at least one hydrolysis inhibitor selected from the group consisting of a series compound is disclosed. However, an aliphatic polyester molded article having flexibility, good moldability, and excellent both heat resistance and impact resistance has not been obtained.
Japanese Patent No. 3410075 JP 2005-60474 A

  An object of the present invention is to provide a biodegradable resin composition having good moldability, excellent heat resistance and impact resistance, and a method for producing a biodegradable resin molded body using the biodegradable resin composition. It is in.

  The present invention is a biodegradable resin composition containing a biodegradable resin, a plasticizer, an organic nucleating agent, and an inorganic nucleating agent, wherein the plasticizer has two or more ester groups in the molecule, Provided is a biodegradable resin composition which is a compound having an average added mole number of oxide of 3 to 9, and the organic nucleating agent is a compound having a hydroxyl group and an amide group in the molecule.

  The present invention also includes the step (1) of mixing the biodegradable resin composition above the melting point (Tm) of the biodegradable resin, the glass transition temperature (Tg) of the biodegradable resin composition and less than Tm. The manufacturing method of the biodegradable resin molding which has the process (2) heat-processed at this temperature.

  The biodegradable resin composition of the present invention has good moldability and excellent heat resistance and impact resistance. Moreover, according to the production method of the present invention, a biodegradable resin molded article having good moldability even at a low mold temperature and having excellent heat resistance and impact resistance can be obtained.

[Biodegradable resin]
The biodegradable resin used in the present invention has a biodegradability based on JIS K6953 (ISO 14855) “Aerobic and ultimate biodegradability and disintegration test under controlled aerobic compost conditions”. The polyester resin which has is preferable.

  The biodegradable resin used in the present invention is not particularly limited as long as it has a biodegradability capable of being decomposed into a low molecular weight compound with the participation of microorganisms in nature. For example, aliphatic polyesters such as polyhydroxybutyrate, polycaprolactone, polybutylene succinate, polybutylene succinate / adipate, polyethylene succinate, polylactic acid resin, polymalic acid, polyglycolic acid, polydioxanone, poly (2-oxetanone) Aliphatic aliphatic copolyesters such as polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polytetramethylene adipate / terephthalate; starch, cellulose, chitin, chitosan, gluten, gelatin, zein, soy protein, collagen, keratin, etc. And a mixture of the above natural polymer and the above aliphatic polyester or aliphatic aromatic copolyester.

  Among these, polylactic acid resin is preferable from the viewpoint of processability, economical efficiency, availability in large quantities, and physical properties. Here, the polylactic acid resin is polylactic acid or a copolymer of lactic acid and hydroxycarboxylic acid. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid and the like, and glycolic acid and hydroxycaproic acid are preferable. A preferred molecular structure of polylactic acid is composed of 20 to 100 mol% of either L-lactic acid or D-lactic acid and 0 to 20 mol% of each enantiomer. The copolymer of lactic acid and hydroxycarboxylic acid is composed of 85 to 100 mol% of either L-lactic acid or D-lactic acid and 0 to 15 mol% of hydroxycarboxylic acid units. These polylactic acid resins can be obtained by dehydrating polycondensation using L-lactic acid, D-lactic acid and hydroxycarboxylic acid as a raw material by selecting those having the required structure. Preferably, it can be obtained by ring-opening polymerization by selecting a desired structure from lactide, which is a cyclic dimer of lactic acid, glycolide, which is a cyclic dimer of glycolic acid, and caprolactone. 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 D-lactide. There is DL-lactide, which is a racemic mixture of lactide and L-lactide. Any lactide can be used in the present invention. However, the main raw material is preferably D-lactide or L-lactide.

  Examples of commercially available biodegradable resins include DuPont, trade name Biomax; BASF, trade name Ecoflex; Eastman Chemicals, trade name EsterBio; Showa Polymer Co., Ltd., trade name Bionore; Made by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Matterby; manufactured by Shimadzu Corporation, trade name: Lakti; made by Mitsui Chemicals, Inc., trade name: Lacia; manufactured by Nippon Shokubai Co., Ltd., trade name: Lunare; Chisso Corporation And trade name Novon; Cargill Dow Polymers, trade name Nature works and the like.

  Of these, polylactic acid resins (for example, trade name Lacia, trade name: Nature works, manufactured by Mitsui Chemicals, Inc .; Cargill Dow Polymers) are preferable.

[Plasticizer]
The plasticizer used in the present invention is a compound having 2 or more ester groups in the molecule and having an average addition mole number of ethylene oxide of 3 to 9, and comprising succinic acid or adipic acid and polyethylene glycol monomethyl ether. It is preferably at least one selected from the group consisting of an ester and an ester of acetic acid and an ethylene oxide adduct of glycerin or ethylene glycol.

The average molecular weight of the plasticizer used in the present invention is preferably from 250 to 700, more preferably from 300 to 600, still more preferably from 350 to 550, particularly preferably from the viewpoint of bleed resistance and volatile resistance. Is 400-500. The average molecular weight can be obtained by calculating the saponification value by the method described in JIS K0070 and calculating from the following formula.
Average molecular weight = 56108 × (number of ester groups) / saponification value

  As a plasticizer used in the present invention, from the viewpoint of excellent moldability and impact resistance of the biodegradable resin molded product, an ester of acetic acid and glycerol with an average of 3 to 9 moles of ethylene oxide adduct, acetic acid and ethylene oxide Alkyl ether esters of polyhydric alcohols such as esters with polyethylene glycol having an average addition mole number of 4 to 9, esters of polyethylene glycol monomethyl ether with an average addition mole number of succinic acid and ethylene oxide of 2 to 4, adipic acid and Esters with polyethylene glycol monomethyl ether having an average addition mole number of ethylene oxide of 2-3, esters of polyethylene glycol monomethyl ether with 1,3,6-hexanetricarboxylic acid and ethylene oxide having an average addition mole number of 2-3, etc. Polyhydric carboxylic acids and polyethylene Esters of glycol monomethyl ether is more preferable. From the viewpoint of excellent moldability, impact resistance and bleed resistance of the plasticizer of the biodegradable resin molded article, an ester of acetic acid and glycerin with an average of 3 to 6 mol of ethylene oxide adduct, an average addition mol of acetic acid and ethylene oxide Esters of polyethylene glycol having a number of 4-6, esters of polyethylene glycol monomethyl ether having an average addition mole number of succinic acid and ethylene oxide of 2-3, esters of adipic acid and diethylene glycol monomethyl ether, 1, 3, 6 -Ester of hexanetricarboxylic acid and diethylene glycol monomethyl ether is more preferable. From the viewpoint of moldability of the biodegradable resin molded article, impact resistance, bleed resistance of the plasticizer, volatility resistance, and irritating odor, an ester of succinic acid and triethylene glycol monomethyl ether is particularly preferable.

  In addition, it is preferable that the ester of this invention is all the esterified saturated ester from a viewpoint of fully exhibiting the function as a plasticizer.

  The reason why the effect of the present invention is improved by a specific plasticizer is not clear, but the plasticizer is a polyoxyethylene chain having 2 or more ester groups in the molecule and an average added mole number of ethylene oxide of 3 to 9 If it is a compound having a (which preferably further has a methyl group, preferably 2 or more), its heat resistance and compatibility with the biodegradable resin will be good. Therefore, the bleed resistance is improved and the softening effect of the biodegradable resin is also improved. It is considered that when the biodegradable resin is crystallized, the growth rate is improved by improving the softening of the biodegradable resin. As a result, since the biodegradable resin retains flexibility even at a low mold temperature, crystallization of the biodegradable resin progresses in a short mold holding time, and good moldability is expected.

[Crystal nucleating agent]
In the present invention, an organic nucleating agent and an inorganic nucleating agent are used as the crystal nucleating agent.
The organic nucleating agent used in the present invention contains a hydroxyl group and an amide group in the organic nucleating agent molecule from the viewpoints of moldability, heat resistance, impact resistance and bloom resistance of the organic nucleating agent. It is preferably an aliphatic compound having two or more hydroxyl groups and two or more amide groups. The melting point of the organic nucleating agent is preferably 65 ° C or higher, more preferably 70 ° C to 220 ° C, and still more preferably 80 to 190 ° C.

  The reason why the effect of the present invention is improved by the organic nucleating agent is not clear, but if it has two or more of the above functional groups, the interaction with the biodegradable resin is improved and the compatibility is improved. It is thought to be due to fine dispersion in the resin. Probably, having one or more, preferably two or more hydroxyl groups improves dispersibility in the biodegradable resin, and one or more amide groups, preferably two. It is considered that the compatibility with the biodegradable resin is improved by having two or more. If the melting point of the crystal nucleating agent is higher than the heat treatment temperature and lower than the kneading temperature of the resin composition, the dispersibility is improved by dissolving the crystal nucleating agent during kneading, and if it is higher than the heat treatment temperature, crystal nucleation is stabilized. And the heat treatment temperature is increased, which is preferable from the viewpoint of improving the crystallization speed. The preferred crystal nucleating agent is considered to precipitate a large number of fine crystals quickly in the cooling process from the resin melt state, and is also preferable from the viewpoint of improving transparency and crystallization speed.

  Examples of the organic nucleating agent of the present invention include hydroxy fatty acid monoamides such as 12-hydroxy stearic acid monoethanolamide, methylene bis 12-hydroxy stearic acid amide, ethylene bis 12-hydroxy stearic acid amide, hexamethylene bis 12-hydroxy stearic acid amide and the like. And hydroxy fatty acid bisamides. From the viewpoints of moldability of the biodegradable resin molding, heat resistance, impact resistance, and bloom resistance of the organic nucleating agent, ethylene bis 12-hydroxystearic acid amide and hexamethylene bis 12-hydroxystearic acid amide are preferable.

  Examples of the inorganic nucleating agent used in the present invention include silicates such as talc, smectite, kaolin, mica, and montmorillonite, silica, and inorganic compounds such as magnesium oxide. An inorganic compound of 20 μm is preferable, and 0.1 to 10 μm is more preferable. Among inorganic compounds, silicate is preferable, talc or mica is more preferable, and talc is still more preferable from the viewpoint of moldability and heat resistance of the biodegradable resin molded body. Silica is preferred from the viewpoint of moldability and transparency of the biodegradable resin molded product.

  In the present invention, by using an organic nucleating agent and an inorganic nucleating agent in combination, the moldability, heat resistance and impact resistance of the biodegradable resin molded article are improved, and the bloom resistance of the organic nucleating agent is also improved. The reason why the effect of the present invention is improved is not clear, but dispersibility deteriorates when the inorganic nucleating agent is used alone. By using the organic nucleating agent in combination, the dispersibility of the inorganic nucleating agent in the resin is improved. Therefore, it is considered that the starting point for crystallization of the biodegradable resin increases and microcrystallization occurs. As a result, since the crystallization speed is improved, crystallization of the biodegradable resin progresses with a short mold holding time and shows good moldability, and since the molded body is dense, the heat resistance and It is considered that the impact resistance is improved. In addition, the interaction between the hydrophilic surface of the inorganic nucleating agent and the polar group of the organic nucleating agent prevents the organic nucleating agent from precipitating (blooming) on the resin surface, thus preventing mold contamination. It is considered a thing.

[Biodegradable resin composition]
The biodegradable resin composition of the present invention contains a biodegradable resin, a plasticizer, an organic nucleating agent, and an inorganic nucleating agent. Particularly preferred combinations of the biodegradable resin, plasticizer, organic nucleating agent and inorganic nucleating agent in the biodegradable resin composition of the present invention include polylactic acid as the biodegradable resin, and succinic acid and triethylene glycol monomethyl as the plasticizer. An ester with ether, an organic nucleating agent is at least one selected from ethylene bis 12-hydroxystearic acid amide and hexamethylene bis 12-hydroxystearic acid amide, and an inorganic nucleating agent is at least one selected from talc, mica and silica. is there.

  As described above, the biodegradable resin composition of the present invention has the effects of the present invention by containing a biodegradable resin, a plasticizer, an organic nucleating agent, and an inorganic nucleating agent. Therefore, even if the plasticizer and the crystal nucleating agent are added alone to a biodegradable resin, particularly polylactic acid resin, the effect of the present invention cannot be obtained.

  Crystallization of the polymer proceeds in two stages by generation of polymer crystal nuclei and diffusion of polymer segments. From the viewpoint of improving the crystallization speed, the above organic nucleating agent dissolves in the resin melt state and improves dispersibility, and upon cooling, a large number of fine crystal nucleating agent crystals are instantly formed, and as a result, polymer crystal nucleation is promoted. In addition, the effect of increasing the number of crystal nuclei is considered to be remarkable. However, even if polymer crystal nuclei are formed, if the diffusion rate of the polymer segment is slow, the total crystallization rate is not satisfactory. In order to improve the diffusion rate of the polymer, the temperature may be increased, but it is not preferable because the crystal nucleus of the polymer becomes unstable. Since the plasticizer has an extremely high effect of improving the crystal growth rate of the polymer, a sufficient crystallization rate can be obtained even at a low temperature of 50 to 90 ° C. Furthermore, the inorganic nucleating agent improves the dispersibility in the resin by the organic nucleating agent, and exhibits the effect of improving the crystal growth rate of the polymer especially at 90 ° C. or higher. As a result, the crystal growth of the polymer over a wide temperature range. The effect of improving the speed is obtained. Further, the inorganic nucleating agent suppresses the organic nucleating agent from precipitating (blooming) on the resin surface. These effects can be realized only by combining the plasticizer, organic nucleating agent and inorganic nucleating agent.

  In order to obtain a sufficient crystallization speed and impact resistance of the present invention, the amount of the plasticizer added is preferably 5 parts by weight or more, more preferably 7 parts by weight or more with respect to 100 parts by weight of the biodegradable resin.

  The content of the biodegradable resin in the biodegradable resin composition of the present invention is preferably 50% by weight or more, more preferably 70% by weight or more from the viewpoint of achieving the object of the present invention.

  The content of the plasticizer in the biodegradable resin composition of the present invention is preferably 5 to 30 parts by weight with respect to 100 parts by weight of the biodegradable resin from the viewpoint of obtaining a sufficient crystallization speed and impact resistance. More preferably, it is more preferably -30 parts by weight, and more preferably 10-30 parts by weight.

  The content of the organic nucleating agent in the biodegradable resin composition of the present invention is preferably 0.1 to 2 parts by weight, more preferably 0.3 to 2 parts by weight, based on 100 parts by weight of the biodegradable resin. .5 to 1.5 parts by weight is particularly preferred.

From the viewpoint of obtaining sufficient crystallization speed and transparency, the content of the inorganic nucleating agent in the biodegradable resin composition of the present invention is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the biodegradable resin. 0.3 to 2 parts by weight is more preferable, and 0.5 to 1.5 parts by weight is particularly preferable.
In addition, from the viewpoint of obtaining a sufficient crystallization speed, heat resistance and impact resistance, the content of the inorganic nucleating agent in the biodegradable resin composition of the present invention is 3 to 100 parts by weight of the biodegradable resin. 50 parts by weight is preferable, 5 to 40 parts by weight is still more preferable, and 5 to 30 parts by weight is particularly preferable.

  In the biodegradable resin composition of the present invention, the difference [Tg1-Tg2] between the glass transition point (Tg1) of the biodegradable resin and the glass transition point (Tg2) of the biodegradable resin composition is 10 to 80. The range of ° C is preferable, the range of 15 to 70 ° C is more preferable, and the range of 20 to 60 ° C is particularly preferable.

  The biodegradable resin composition of the present invention can further contain a hydrolysis inhibitor in addition to the crystal nucleating agent and the plasticizer of the present invention. Examples of the hydrolysis inhibitor include carbodiimide compounds such as polycarbodiimide compounds and monocarbodiimide compounds, polycarbodiimide compounds are preferred from the viewpoint of moldability of the biodegradable resin molded body, and the heat resistance of the biodegradable resin molded body, From the viewpoint of impact resistance and bloom resistance of the organic nucleating agent, a monocarbodiimide compound is preferred.

  Examples of the polycarbodiimide compound include poly (4,4′-diphenylmethanecarbodiimide), poly (4,4′-dicyclohexylmethanecarbodiimide), poly (1,3,5-triisopropylbenzene) polycarbodiimide, and poly (1,3,5). -Triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide and the like, and examples of the monocarbodiimide compound include N, N'-di-2,6-diisopropylphenylcarbodiimide.

  The carbodiimide compounds may be used alone or in combination of two or more in order to satisfy the moldability, heat resistance, impact resistance and bloom resistance of the organic nucleating agent of the biodegradable resin molded product. Poly (4,4′-dicyclohexylmethanecarbodiimide) is obtained from carbodilite LA-1 (manufactured by Nisshinbo Co., Ltd.), poly (1,3,5-triisopropylbenzene) polycarbodiimide and poly (1,3,5). -Triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide are stabuxol P and stabuxol P-100 (Rhein Chemie), N, N'-di-2,6-diisopropylphenylcarbodiimide is stabuxol I (Rhein Chemie) Can be purchased and used.

  The content of the hydrolysis inhibitor in the biodegradable resin composition of the present invention is 0.05 to 3 parts by weight with respect to 100 parts by weight of the biodegradable resin from the viewpoint of moldability of the biodegradable resin molded article. Preferably, 0.1 to 2 parts by weight is more preferable.

  In addition to the above, the biodegradable resin composition of the present invention further contains other components such as a hindered phenol or phosphite antioxidant, or a hydrocarbon wax or a lubricant that is an anionic surfactant. can do. The content of each of the antioxidant and the lubricant is preferably 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the biodegradable resin.

  The biodegradable resin composition of the present invention includes an antistatic agent, an antifogging agent, a light stabilizer, an ultraviolet absorber, a pigment, an inorganic filler, an antifungal agent, an antibacterial agent and a foaming agent as components other than those described above. In addition, flame retardants and the like can be contained as long as the object of the present invention is not hindered.

  Since the biodegradable resin composition of the present invention has good processability and can be processed at a low temperature of, for example, 200 ° C. or lower, there is also an advantage that the plasticizer is hardly decomposed. It can be used for various purposes.

[Production method of biodegradable resin molding]
The method for producing the biodegradable resin molded article of the present invention comprises the step (1) of mixing the biodegradable resin composition of the present invention at a melting point (Tm) or higher of the biodegradable resin, and the biodegradable resin composition. And (2) a heat treatment at a temperature not lower than the glass transition temperature (Tg) and lower than Tm.

  In addition, after passing through the step (1), after cooling to an amorphous state (that is, a condition that the degree of crystallinity measured by high angle X-ray diffraction method is 1% or less), the method of performing the step (2) After the step (1), the method of cooling and immediately performing the step (2) is preferable. From the viewpoint of the crystallization speed improvement effect of the present invention, the step (1) is followed by cooling and the step (1). The method of performing 2) is more preferable.

  As a specific example of the step (1) in the method for producing a biodegradable resin molded body of the present invention, it can be performed by a usual method, for example, while melting the biodegradable resin using an extruder or the like, The method etc. which mix the plasticizer of this invention, an organic nucleating agent, and an inorganic nucleating agent are mentioned. The temperature of the step (1) is not less than the melting point (Tm) of the biodegradable resin from the viewpoint of dispersibility of the plasticizer, organic nucleating agent and inorganic nucleating agent of the present invention, preferably in the range of Tm to Tm + 100 ° C. More preferably, it is the range of Tm-Tm + 50 degreeC. For example, when the biodegradable resin is a polylactic acid resin, the temperature is preferably 170 to 240 ° C, more preferably 170 to 220 ° C.

  As a specific example of the step (2) in the method for producing a molded article of the present invention, it can be carried out by an ordinary method, for example, a method of heat-treating or injection of a biodegradable resin composition extruded by an extruder or the like. Examples thereof include a method in which a biodegradable resin composition is filled in a mold with a molding machine or the like and the biodegradable resin composition is heat-treated. From the viewpoint of improving the crystallization speed, the temperature in the step (2) is not less than the glass transition temperature (Tg) of the biodegradable resin composition and less than Tm, preferably in the range of Tg to Tg + 100 ° C., more preferably Tg + 10. It is the range of -Tg + 80 degreeC, Most preferably, it is the range of Tg + 20-Tg + 70 degreeC. For example, in the case of a biodegradable resin composition in which the biodegradable resin is a polylactic acid resin, 50 to 90 ° C is preferable, and 70 to 80 ° C is more preferable.

  In addition, melting | fusing point (Tm) of biodegradable resin is a value calculated | required from the crystal melting endothermic peak temperature by the temperature rising method of differential scanning calorimetry (DSC) based on JIS-K7121. Moreover, the glass transition temperature (Tg) of a biodegradable resin composition is a value calculated | required from the peak temperature of the loss elastic modulus (E '') in the dynamic viscoelasticity measurement based on JIS-K7198.

  The thermal deformation temperature of the biodegradable resin molded product of the present invention varies depending on the type and amount of biodegradable resin, plasticizer, and crystal nucleating agent and cannot be determined unconditionally. In this case, from the viewpoint of expressing the effect of the present invention, 70 ° C. or higher is preferable, 75 ° C. or higher is more preferable, and 80 ° C. or higher is still more preferable. In addition, the heat distortion temperature of the biodegradable resin molding of this invention is a value measured by the measuring method described in the Example here.

  The impact resistance of the biodegradable resin molded product of the present invention cannot be determined unconditionally because it varies depending on the type and amount of biodegradable resin, plasticizer, and crystal nucleating agent. In this case, from the viewpoint of manifesting the effects of the present invention, 60 (J / m) or more is preferable, 70 (J / m) or more is more preferable, and 80 (J / m) or more is more preferable. Here, the impact resistance of the biodegradable resin molded product of the present invention is a value measured by the measurement method described in the examples.

  In the case of a polylactic acid resin, the total transmittance (%) at a thickness of 3 mm of the biodegradable resin molded product of the present invention is preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. Here, the total transmittance (%) can be measured using an integrating sphere light transmittance measuring device (haze meter) defined in JIS-K7105.

  The degree of crystallinity of the biodegradable resin molded product of the present invention cannot be determined unconditionally because it varies depending on the type and amount of biodegradable resin, plasticizer, and crystal nucleating agent. In the case, from the viewpoint of expressing the effect of the present invention, it is preferably 30 to 70%, more preferably 40 to 70%, and particularly preferably 50 to 65%. In addition, the crystallinity degree of the biodegradable resin molding of this invention is a value measured by the measuring method described in the Example here.

Examples 1-6, Comparative Examples 1-6
The present invention products (A to F) and comparative products (af) shown in Table 1 as biodegradable resin compositions are subjected to 180 ° C. for 10 minutes using a kneader (DS3-20MWB-E manufactured by Moriyama Seisakusho). It is melt-kneaded, and then immediately stretched to a thickness of about 5 mm with an 8-inch roll (manufactured by Nippon Roll Manufacturing Co., Ltd.) at 80 ° C. and cut into a size of about 8 cm × 8 cm in length × width = 8 ° C. The product was pulverized by a pulverizer (S-20 manufactured by Daiko Seiki Co., Ltd.) to obtain a pulverized product of the biodegradable resin composition.

  The obtained pulverized product was dried at 70 ° C. under reduced pressure for 1 day, and the water content was adjusted to 500 ppm or less.

* 1: Polylactic acid resin (manufactured by Mitsui Chemicals, LACEA H-400)
* 2: Diester of succinic acid and triethylene glycol monomethyl ether * 3: Ethylene bis 12-hydroxystearic acid amide (Nippon Kasei Co., Ltd., SLIPAX H)
* 4: Nihon Talc Co., Ltd., Micro Ace P-6
* 5: Hexamethylene bis 12-hydroxystearic acid amide (Nippon Kasei Co., Ltd., SLIPAX ZHH)
* 6: Acetic ester of glycerin ethylene oxide 6 mol adduct * 7: Hayashi Kasei Co., Ltd., Mica WG-325
* 8: Diglycerin tetraacetate * 9: Acetyl polyethylene glycol monomethyl ether (manufactured by Sanyo Chemical Co., Ltd., polyethylene glycol skeleton molecular weight 400)
* 10: Fatty acid amide E, manufactured by Kao Corporation

  Next, the pulverized product thus obtained was injection molded using an injection molding machine (Japan Steel Works J75E-D) with a cylinder temperature of 200 ° C., and the mold temperatures and molds shown in Table 2 were used. Mold releasability of test pieces [flat plate (70mm x 40mm x 3mm), prismatic specimen (125mm x 12mm x 6mm) and prismatic specimen (63mm x 12mm x 5mm)] during the holding time based on the following criteria evaluated. Further, mold contamination after 100 shots of injection was evaluated according to the following criteria. Furthermore, the bleed resistance and transparency of the obtained flat plate (70 mm × 40 mm × 3 mm) were evaluated by the following methods. These results are shown in Table 2.

<Evaluation criteria for mold releasability>
○: Very easy to leave (the test piece is not deformed and can be taken out easily)
Δ: Slightly difficult to separate (test piece is slightly deformed and difficult to remove)
X: Not separated (the test piece is greatly deformed and does not leave the runner)
The mold releasability becomes better as the melt crystallization speed of the test piece increases in the mold and in the runner portion.

<Evaluation criteria for mold contamination>
Mold contamination after 100 shots of injection was visually evaluated.
○: No contamination △: Some contamination ×: Very contamination <Bleed resistance>
The injection-molded flat plate (70 mm × 40 mm × 3 mm) was left under high temperature and high humidity of 50 ° C./80% Rh for 3 months, and the presence or absence of plasticizer bleed on the surface was observed with the naked eye.

<Transparency>
About the flat plate after injection molding (70 mm × 40 mm × 3 mm), the total transmittance (%) of the 3 mm thick flat plate was measured using an integrating sphere type light transmittance measuring device (haze meter) defined in JIS-K7105. Larger numbers indicate better transparency.

  From the results in Table 2, the biodegradable resin composition (A to F) of the present invention containing a specific plasticizer and organic nucleating agent and talc or mica has a short mold holding time even at a mold temperature of 80 ° C. The molded product was good in bleed resistance under high temperature and high humidity. Further, it is understood that the transparency is hardly lowered despite satisfying excellent moldability.

  On the other hand, resin compositions (a to c and e) not containing an inorganic nucleating agent or a specific organic nucleating agent and resin compositions not containing a specific plasticizer (d and f) are short at a mold temperature of 80 ° C. Molding with the mold holding time was impossible. In addition, the resin compositions (a and b) containing only the organic nucleating agent are likely to contaminate the mold during injection molding when the content of the organic nucleating agent is increased, and the resin compositions containing conventional plasticizers (d and f) ) Was poor in bleed resistance under high temperature and high humidity.

Examples 7-17, Comparative Examples 7-10
The present invention products (G to Q) and comparative products (g to j) shown in Table 3 as biodegradable resin compositions were subjected to 180 ° C. for 10 minutes using a kneader (DS3-20MWB-E manufactured by Moriyama Seisakusho Co., Ltd.). It is melt-kneaded, and then immediately stretched to a thickness of about 5 mm with an 8-inch roll (manufactured by Nippon Roll Manufacturing Co., Ltd.) at 80 ° C. and cut into a size of about 8 cm × 8 cm in length × width = 8 ° C. The product was pulverized by a pulverizer (S-20 manufactured by Daiko Seiki Co., Ltd.) to obtain a pulverized product of the biodegradable resin composition.

  The obtained pulverized product was dried at 70 ° C. under reduced pressure for 1 day, and the water content was adjusted to 500 ppm or less.

* 11: Nisshinbo product, Carbodilite LA-1
* 12: Bis (diisopropylphenyl) carbodiimide * 13: Mizusawa Chemical Co., Ltd., Mizukacil P-526
* 14: Caprylic acid monoglyceride diacetate

  Next, the pulverized product thus obtained was injection molded using an injection molding machine (J75E-D manufactured by Nippon Steel Works) with a cylinder temperature of 200 ° C., and the mold temperatures and molds shown in Table 4 were used. The mold releasability of the test piece [flat plate (70 mm × 40 mm × 3 mm), prismatic test piece (125 mm × 12 mm × 6 mm) and prismatic test piece (63 mm × 12 mm × 5 mm)] during the holding time as in Example 1 Evaluation was made according to the same criteria. Further, mold contamination after 100 shots of injection was evaluated according to the same criteria as in Example 1. Furthermore, the bleed resistance and transparency of the obtained flat plate (70 mm × 40 mm × 3 mm) were evaluated in the same manner as in Example 1. These results are shown in Table 4.

  From the results of Table 4, the biodegradable resin composition (G to Q) of the present invention containing a specific plasticizer and an organic nucleating agent, talc, mica or silica, and further containing a hydrolysis inhibitor, Molding was possible with a short mold holding time even at a mold temperature of 80 ° C., and the molded product had good bleed resistance under high temperature and high humidity. In addition, it can be seen that the biodegradable resin compositions (G and K to Q) have little decrease in transparency despite satisfying excellent moldability.

  On the other hand, resin compositions (g and h) that do not contain an inorganic nucleating agent or a specific organic nucleating agent or resin compositions (i and j) that do not contain a specific plasticizer have a short mold at a mold temperature of 80 ° C. Molding with the holding time was impossible. In addition, when the resin composition (g) containing only the organic nucleating agent contains a polycarbodiimide compound, the resin composition (i) containing a conventional plasticizer is likely to be contaminated with a mold at the time of injection molding. Bleed resistance under humidity was poor.

Examples 18-28, Comparative Examples 11-14
Using the products (G to Q) and comparative products (g to j) shown in Table 3 as biodegradable resin compositions, the biodegradable resins were used in the same manner as in Examples 7 to 17 and Comparative Examples 7 to 10. A pulverized product of the composition was obtained.

  The obtained pulverized product was injection molded using an injection molding machine (J75E-D, manufactured by Nippon Steel Works) at a mold temperature and mold holding time with good mold releasability shown in Table 5. About the obtained test piece [flat plate (70 mm × 40 mm × 3 mm), prismatic test piece (125 mm × 12 mm × 6 mm) and prismatic test piece (63 mm × 12 mm × 5 mm)], a prismatic test piece (125 mm × 12 mm × 6 mm) was evaluated for heat distortion temperature, prismatic specimens (63 mm × 12 mm × 5 mm) were evaluated for impact resistance, and flat plates (70 mm × 40 mm × 3 mm) were evaluated for crystallinity by the following methods. These results are shown in Table 5.

<Heat deformation temperature>
For a prismatic test piece (125 mm x 12 mm x 6 mm), the temperature at which the heat deflection temperature measuring machine (Toyo Seiki Seisakusho B-32) is deflected by 0.025 mm at a load of 0.45 MPa is based on JIS-K7191. It was measured.

<Impact resistance>
The Izod impact strength of a prismatic test piece (63 mm × 12 mm × 5 mm) was measured using an impact tester (type 863 manufactured by Ueshima Seisakusho Co., Ltd.) based on JIS-K7110.

<Crystallinity>
Use a wide-angle X-ray diffraction measurement device (RINT2500VPC, light source CuKα, tube voltage 40kV, tube current 120mA, manufactured by Rigaku Corporation) for the flat plate after injection molding (70mm × 40mm × 3mm) 2θ = 5-30 ° The crystallinity was determined by analyzing the amorphous and crystalline peak areas in the range.

  From the results of Table 5, the biodegradable resin composition (G to Q) of the present invention containing a specific plasticizer and organic nucleating agent, talc, mica or silica, and further containing a hydrolysis inhibitor, Molding was possible with a short mold holding time even at a mold temperature of 80 ° C., and the molded product was excellent in exhibiting heat resistance of 75 ° C. or higher and impact resistance of 70 J / m or higher.

  On the other hand, a resin composition (g and h) that does not contain an inorganic nucleating agent or a specific organic nucleating agent or a resin composition (i) that does not contain a specific plasticizer, The mold temperature requires a long mold holding time, and the resin composition (j) containing no plasticizer requires a long mold holding time even at a mold temperature of 110 ° C. in order to obtain a good molded product. Further, the obtained molded product could not achieve both excellent heat resistance and impact resistance.

From the above results, the biodegradable resin composition of the present invention containing a specific plasticizer, an organic nucleating agent and an inorganic nucleating agent exhibits excellent moldability at a low mold temperature, and the molded product has a high temperature and high humidity. The bleed resistance below is also good, and it can be seen that both excellent heat resistance and impact resistance are achieved.

Claims (9)

  Biodegradable resin composition containing a biodegradable resin, a plasticizer, an organic nucleating agent and an inorganic nucleating agent, wherein the plasticizer has two or more ester groups in the molecule, and an average addition of ethylene oxide A biodegradable resin composition, which is a compound having 3 to 9 moles and the organic nucleating agent is a compound having a hydroxyl group and an amide group in the molecule.   The content of the plasticizer is 5 to 30 parts by weight, the content of the organic nucleating agent is 0.1 to 2 parts by weight, and the content of the inorganic nucleating agent is 0.1 to 2 parts by weight based on 100 parts by weight of the biodegradable resin. The biodegradable resin composition according to claim 1, which is a part.   The plasticizer is at least one selected from the group consisting of an ester of succinic acid or adipic acid and polyethylene glycol monomethyl ether, and an ester of acetic acid and glycerin or an ethylene oxide adduct of ethylene glycol. Biodegradable resin composition.   The biodegradation according to any one of claims 1 to 3, wherein the organic nucleating agent is at least one selected from methylene bis 12-hydroxystearic acid amide, ethylene bis 12-hydroxystearic acid amide, and hexamethylene bis 12-hydroxystearic acid amide. Resin composition.   The biodegradable resin composition according to any one of claims 1 to 4, wherein the inorganic nucleating agent is talc.   The biodegradable resin composition according to any one of claims 1 to 5, wherein the biodegradable resin is a polylactic acid resin.   A step (1) of mixing the biodegradable resin composition according to any one of claims 1 to 6 at a melting point (Tm) or higher of the biodegradable resin, and a glass transition temperature (Tg) or higher of the biodegradable resin composition A method for producing a biodegradable resin molded body, comprising a step (2) of heat-treating at a temperature lower than Tm.   The manufacturing method of the biodegradable resin molding of Claim 7 which performs a process (2) in a metal mold | die. The method for producing a biodegradable resin molded article according to claim 7 or 8, wherein the temperature in step (2) is 50 to 90 ° C.