JP2015063645A - Polylactic acid-based resin composition and molded article prepared using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid-based resin composition having a persistent antibacterial property and sufficient stability.SOLUTION: A polylactic acid-based resin composition having an antibacterial property comprises a polylactic acid-based resin, and an inorganic compound showing from 4.0 to 10.0 of pH of 0.1 mass% aqueous solution.

Description

  The present invention relates to a polylactic acid resin composition and a molded body using the same.

  Polyhydroxycarboxylic acids including polylactic acid resins have relatively excellent moldability, toughness, rigidity, and the like. Among them, polylactic acid resin can be synthesized from natural raw materials such as corn, and has excellent molding processability, biodegradability, etc., and therefore is being developed as an environmentally friendly resin in various fields. . However, polylactic acid resin has excellent physical properties, but is inferior in antibacterial properties. Therefore, in order to use such polylactic acid resin for equipment and equipment such as housing equipment, public facilities and stores that require a high degree of antibacterial properties, as well as exterior materials for electronic devices, antibacterial performance is enhanced. There is a need.

  Many attempts have been made to impart antibacterial properties to resin compositions containing such polylactic acid resins. For example, Patent Document 1 discloses a phosphonic acid metal salt formed from a biodegradable polyester, that is, polylactic acid, a phosphonic acid compound having an aromatic ring and a metal ion selected from silver ions, copper ions, and zinc ions. Resin compositions added with antibacterial properties as antibacterial agents are listed. However, if parts molded with this resin composition are immersed in warm water, wiped with household detergent, or irradiated with light, metal ions will elute or the antibacterial agent will deteriorate, resulting in antibacterial performance. Decrease significantly. Such a resin composition is difficult to express a sustained antibacterial property, and is practically required for housing equipment, facilities and equipment such as public facilities and stores, and exterior materials for electronic equipment. Lack.

  Patent Document 2 discloses an example of a resin composition using a food additive such as glycerin fatty acid ester, sucrose fatty acid ester, and tea extract as an antibacterial agent in polylactic acid. However, when a part molded with this resin composition is immersed in warm water or wiped with a household detergent, the food additive itself is eluted, and the antibacterial performance is significantly reduced. Such a resin composition is difficult to express a sustained antibacterial property, and is practically required for housing equipment, facilities and equipment such as public facilities and stores, and exterior materials for electronic equipment. Lack.

  In addition, antibacterial agents manufactured by calcining scallop shells, which are mainly composed of calcium carbonate, are converted into calcium oxide and then converted into calcium hydroxide by adding water (commercially available from Antibacterial Laboratories, Inc. Name: Scarlow). However, since this antibacterial agent is strongly alkaline, if it is added to the polylactic acid resin, the decomposition of the polylactic acid resin is promoted. Therefore, the polylactic acid resin composition containing such an antibacterial agent can be used at the time of molding or storage. There is a problem with stability. Therefore, it lacks the practicality required for housing equipment, facilities and equipment such as public facilities and stores, and exterior materials for electronic equipment.

  In addition, Patent Document 3 includes an inorganic porous material such as zeolite supporting one or more metals selected from copper, silver, and zinc, a transition structure layer made of microfibers, and this layer. An antibacterial / dustproof fabric comprising a nanofiber nonwoven fabric layer containing nanofibers made of polylactic acid and / or polyamide laminated on the substrate is described.

Japanese Patent No. 4591622 JP 2011-12221 A JP 2008-188791 A

  An object of the present invention is to solve the above-described problems, and to provide a polylactic acid resin composition having sustained antibacterial properties and sufficient stability, and a molded body using the same.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the polylactic acid resin (A),
Acquired knowledge that can achieve both continuous antibacterial properties and stability by using an inorganic compound (B) in which the pH (hydrogen ion concentration) of a 0.1% by mass aqueous solution is 4.0 to 10.0. It was. Based on this finding, the present invention has been completed.
The antimicrobial polylactic acid resin composition according to one embodiment of the present invention has a polylactic acid resin (A) and a pH (hydrogen ion concentration) of a 0.1% by mass aqueous solution of 4.0 to 10.0. Inorganic compound (B) is included.

  Moreover, the molded object by the other aspect of this invention is a thing obtained by shape | molding said polylactic acid-type resin composition.

  According to the embodiment of the present invention, it is possible to provide a polylactic acid resin composition having a continuous antibacterial property and sufficient stability, and a molded body using the same.

  The polylactic acid-based resin composition according to the embodiment of the present invention can simultaneously achieve sustained antibacterial properties and sufficient stability (the resin is difficult to be decomposed during molding and storage). The reason is considered as follows. That is, by using together the polylactic acid resin (A) and the inorganic compound (B) having a pH (hydrogen ion concentration) of 0.1 mass% aqueous solution of 4.0 to 10.0, an antibacterial component (for example, It is considered that the sustained release rate of zinc ions and silver ions) can be controlled, so that the antibacterial durability can be increased. In addition, since the inorganic compound (B) does not promote the decomposition of the polylactic acid-based resin (A), the polylactic acid-based resin containing the polylactic acid-based resin (A) and the inorganic compound (B) is melt-kneaded. It is possible to suppress deterioration due to decomposition when the resin composition and the molded body thereof are stored at high temperature and high humidity for a long time.

  Such polylactic acid-based resin compositions are used in applications where sustained antibacterial properties and stability are required, such as housing equipment, facilities and equipment such as public facilities and stores, and electronic equipment casings. It is suitable for the exterior material. Moreover, since the polylactic acid resin contained in this resin composition is obtained from natural raw materials and the polylactic acid resin is biodegradable, it can reduce the environmental burden even during production and disposal. it can.

The polylactic acid-based resin composition according to the embodiment of the present invention contains the polylactic acid-based resin (A) as a main component, and the pH (hydrogen ion concentration) of a 0.1 mass% aqueous solution is 4.0 to 10.0. The inorganic compound (B) shown is contained as an essential component.
Here, the “main component” means a main component in the organic component constituting the polylactic acid resin composition, and it is allowed to contain other components within a range that does not hinder the function of the composition. means. In particular, the content ratio of the main component (base resin) is not specified, but the main component is 50% by mass or more, preferably 70% by mass or more, more preferably in the organic component constituting the polylactic acid-based composition. Includes 80% by mass or more, particularly preferably 90% by mass or more. Therefore, in the polylactic acid-based resin composition according to the embodiment of the present invention, the content of the polylactic acid-based resin (A) is 50% by mass or more with respect to the entire organic components constituting the polylactic acid-based resin composition. , Preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more. The content of the resin component in the polylactic acid-based resin composition can be set to, for example, 40% by mass or more, preferably 50% by mass or more, and more preferably 60% by mass or more.

As the polylactic acid resin (A), an extract of polylactic acid resin obtained from a biomass raw material or a derivative or modified product thereof, or a monomer or oligomer of a lactic acid compound obtained from a biomass raw material, or a derivative thereof or Examples include condensation polymers synthesized using a modified product. In addition, the resin containing the segment of the polylactic acid-type resin synthesize | combined using raw materials other than biomass raw material can be mentioned.
Examples of the polylactic acid resin (A) include those represented by the following formula (1).

In the formula (1), R ₁₇ represents an alkyl group having 18 or less carbon atoms, a and c are integers greater than 0, and b ′ represents an integer of 0 or more. a is preferably an integer of 500 or more and 13000 or less, more preferably an integer of 1500 or more and 4000 or less. b ′ is preferably an integer of 0 to 5000, and c is preferably an integer of 1 to 50. In the polylactic acid-based resin represented by the formula (1), the repeating units represented by the number of repeating units a and b ′ may be the same type of repeating units connected continuously or may be repeated alternately. .
Specific examples of the polylactic acid-based resin represented by the formula (1) include an L-lactic acid polymer, a D-lactic acid polymer, a polymer of these lactic acid derivatives, and these as main components. Mention may be made of copolymers and mixtures of two or more of these polymers. Examples of such a copolymer include L-lactic acid, D-lactic acid, and derivatives thereof, for example, glycolic acid, polyhydroxybutyric acid, polycaprolactone, polybutylene succinate, polyethylene succinate, polybutylene adipate terephthalate, polybutylene succinate. Mention may be made of copolymers obtained from one or more of terephthalate, polyhydroxyalkanoate and the like. Such a copolymer is preferably a polymer having a unit derived from lactic acid of 80 mol% or more, more preferably 90 mol% or more from the viewpoint of saving petroleum resources, heat resistance, moldability and the like. Among these polymers, those derived from plants are preferred from the viewpoint of saving petroleum resources, and from the viewpoint of heat resistance and moldability, poly (L-lactic acid), poly (D-lactic acid) are preferred. A copolymer of L-lactic acid and D-lactic acid is particularly preferred. The melting point of polylactic acid mainly composed of poly (L-lactic acid) varies depending on the ratio of the D-lactic acid component, but considering the mechanical properties and heat resistance of the molded product, the melting point is 160 ° C. or higher. What has is preferable.

  The weight average molecular weight of the polylactic acid-based resin is preferably 30,000 to 1,000,000, more preferably 100,000 to 300,000.

  In addition, polylactic acid resins can be polymerized by crosslinking them with compounds that can react with polylactic acid resins, such as carbodiimide compounds, compounds having epoxy groups, compounds having amino groups, and compounds having aliphatic unsaturated double bonds. Polylactic acid based resins can also be used. Examples of the compound having an epoxy group, the compound having an amino group, and the compound having an aliphatic unsaturated double bond include siloxane compounds having these functional groups.

  As an inorganic compound (B) in which the pH (hydrogen ion concentration) of a 0.1 mass% aqueous solution, which is an essential component of the polylactic acid resin composition according to the embodiment of the present invention, is 4.0 to 10.0, silver is used. Inorganic compounds capable of sustained release of antibacterial components such as ions and metal ions such as zinc ions are preferred. As such an inorganic compound (B), a compound having a zeolite structure such as a phosphoric acid complex or an aluminosilicate, or a compound containing a zinc component (for example, a zinc compound such as zinc oxide or a zinc ion) is preferable. An inorganic compound having a zinc component is more preferable. Among these, a composite of aluminosilicate and phosphoric acid holding zinc ions and silver ions capable of sustained release of zinc ions and silver ions, and a composite of aluminosilicate and zinc oxide holding silver ions capable of sustained release of silver ions. One compound selected from the above or a mixture of two or more are preferred.

  From the viewpoint of the stability of the polylactic acid resin composition, the inorganic compound (B) is more preferably a compound in which the pH of a 0.1% by mass aqueous solution is 4.0 to 8.0.

  An inorganic compound (B) can also be used in the state surface-treated with the silane coupling agent, for example. The method for surface-treating the metal hydroxide with a silane coupling agent is not particularly limited. For example, a solution obtained by dissolving a silane coupling agent in a solvent such as acetone, ethyl acetate, toluene, or the like is used. Examples include a method of removing the solvent by spraying or coating on the surface and then drying.

By adding the inorganic compound (B) to the polylactic acid-based resin (A), the obtained resin composition can exhibit a continuous antibacterial property. This antibacterial sustainability improving effect is considered to result from the sustained release of metal ions such as zinc ions and silver ions by the inorganic compound (B).
Content of an inorganic compound (B) can be set to the range of 0.1-15 mass% as a mass ratio which occupies for the sum total of a polylactic acid-type resin (A) and an inorganic compound (B). From the viewpoint of obtaining a sufficient addition effect of the inorganic compound (B), the content of the inorganic compound (B) is preferably 0.1% by mass or more. From the viewpoint of stably producing a master batch of the polylactic acid resin (A) and the inorganic compound (B), and from the viewpoint of molding stability, the content of the inorganic compound (B) is preferably 15% by mass or less, 10 mass% or less is more preferable, 8 mass% or less is further more preferable, and 5 mass% or less is especially preferable. When an inorganic compound (B) showing a high pH value of a 0.1% by mass aqueous solution (for example, pH is greater than 8.0 and 10.0 or less, and pH is 9.0 or more and 10.0 or less), molding is performed. From the viewpoint of stability, the content of the inorganic compound (B) is preferably 8% by mass or less, and more preferably 5% by mass or less.
It is preferable that content of the zinc ion in an inorganic compound (B) exists in the range of 0.1-18 mass%. It is preferable that content of the silver ion in an inorganic compound (B) exists in the range of 0.1-5 mass%.

  In addition, examples of components that can be used in the resin composition according to the embodiment of the present invention include flame retardants such as halogen compounds and phosphorus compounds, inorganic flame retardants, hydrolysis resistance inhibitors, fibers, and fluorine-containing resins. .

  As the phosphorus compound, a phosphazene derivative and an aromatic condensed phosphate ester are preferable because they have an excellent flame retardant effect. Examples of the phosphazene derivative include cyclic compounds represented by the following general formulas as cyclic cyclophosphazene compounds.

（式中、ｎは３以上の整数を示し、Ｒ^１及びＲ^２はそれぞれ有機基を示す。）

(In the formula, n represents an integer of 3 or more, and R ¹ and R ² each represents an organic group.)

N in the formula is preferably in the range of 3 to 25, and more preferably in the range of 3 to 5. The cyclophosphazene compound can independently have, for example, a substituted or unsubstituted phenoxy group or a substituted or unsubstituted naphthoxy group (for example, β-naphthoxy) as R ¹ and R ² .

  Phosphazene derivatives that are one of phosphorus compounds include cyclophosphazene compounds having a phenoxy group, cyclophosphazene compounds having a cyanophenoxy group, cyclophosphazene compounds having an aminophenoxy group, and cyclophosphazene compounds having a substituted or unsubstituted naphthoxy group And cyclophosphazene compounds having a phenolic hydroxyl group, and one or a mixture of two or more thereof can be used. However, it is preferable that the phenolic hydroxyl group does not contain a phenolic hydroxyl group because it easily forms a quinone structure that causes coloring when oxidized. That is, from the viewpoint of color fastness, the cyclophosphazene compound is a cyclophosphazene compound having a phenoxy group, a cyclophosphazene compound having a cyanophenoxy group, a cyclophosphazene compound having an aminophenoxy group, a cyclophosphazene compound having a substituted or unsubstituted naphthoxy group. At least one compound selected from the group consisting of phosphazene compounds is preferred. Such a cyclophosphazene compound is preferably cyclotriphosphazene, cyclotetraphosphazene or cyclopentaphosphazene having a substituted or unsubstituted phenoxy group or a substituted or unsubstituted naphthoxy group, and a cyclopentaphosphazene having a substituted or unsubstituted phenoxy group. Triphosphazene can be preferably used. For example, hexaphenoxycyclotriphosphazene (the phenoxy group may have a substituent) is mentioned.

  Examples of the aromatic condensed phosphoric acid ester which is one of the phosphorus compounds include resorcinol bisdiphenyl phosphate, bisphenol A-bisdiphenyl phosphate, resorcinol-bis-2,6-xylenyl phosphate, resorcinol-bis-2,6. -Bisdiphenyl phosphate, biphenol-bisdiphenyl phosphate, 4,4'-bis (diphenylphosphoryl) -1,1'-biphenyl and the like.

  The compounding amount of the phosphorus compound is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and more preferably 3 parts by mass or more with respect to 100 parts by mass of the polylactic acid-based resin, from the viewpoint of obtaining a flame retardancy improvement effect according to the addition Is more preferable. On the other hand, from the viewpoint of bleed resistance, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less, and particularly preferably 7 parts by mass or less.

  Moreover, metal hydroxides, such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide, can be used as an inorganic flame retardant. In addition to the above-mentioned flame retardants, nitrogen-based flame retardants, melamine cyanurate, high molecular weight phosphaphenanthrene derivatives, and the like can also be used. An example of the high molecular weight phosphaphenanthrene derivative is ME-P8 (trade name) manufactured by Sanko Co., Ltd. From the viewpoint of obtaining particularly good fluidity, it is more preferable to use melamine cyanurate.

As the hydrolysis resistance inhibitor, for example, carbodiimide compounds are preferable. A carbodiimide compound is a compound having at least one carbodiimide group in the molecule. Such carbodiimides include dicyclohexylcarbodiimide, diisopropylcarbodiimide, diphenylcarbodiimide, bis (methylphenyl) carbodiimide, bis (methoxyphenyl) carbodiimide, bis (nitrophenyl) carbodiimide, bis (dimethylphenyl) carbodiimide, bis (diisopropyl) carbodiimide, Bis (t-butyl) carbodiimide, N-ethyl-N ′-(3-dimethylaminopropyl) carbodiimide, bis (triphenylsilyl) carbodiimide, N, N′-di-2,6-diisopropylphenylcarbodiimide can be mentioned. As a commercial product of N, N′-di-2,6-diisopropylphenylcarbodiimide, Stabuxol I (trade name) manufactured by Rhein Chemie can be used. Examples of the carbodiimide-based compound (polycarbodiimide) having two or more carbodiimide groups include aliphatic polycarbodiimides such as poly (4,4′-dicyclohexylmethanecarbodiimide); poly (4,4′-diphenylmethanecarbodiimide), poly (p- Phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (methylphenylenecarbodiimide), poly (diisopropylphenylenecarbodiimide), poly (methyldiisopropylphenylenecarbodiimide), poly (1,3,5-triisopropylphenylenecarbodiimide), poly ( And aromatic polycarbodiimides such as 1,3,5-triisopropylphenylene and 1,5-diisopropylphenylenecarbodiimide). As the aliphatic polycarbodiimide, an aliphatic polycarbodiimide having an alicyclic structure such as a cyclohexane ring is preferable. For example, polycarbodiimide in which the organic linking group R in the general formula “— (N═C═N—R) _n —” (n is an integer of 2 or more) includes at least an alicyclic divalent group such as a cyclohexylene group. Is mentioned. As such an aliphatic polycarbodiimide, poly (4,4′-dicyclohexylmethanecarbodiimide) can be suitably used. As a commercial product of this poly (4,4′-dicyclohexylmethanecarbodiimide), Carbodilite LA-1 (trade name) manufactured by Nisshinbo Chemical Co., Ltd. can be used. Examples of the aromatic polycarbodiimide include polycarbodiimide having an aromatic ring structure such as a benzene ring. As an aromatic polycarbodiimide, it is possible to use, as a commercial product, stabuxol P (trade name, poly (1,3,5-triisopropylphenylenecarbodiimide)) or stabuxol P-100 (trade name) manufactured by Rhein Chemie. it can.

  The blending amount of the carbodiimide compound can be set to 0.1 parts by mass or more with respect to 100 parts by mass of the polylactic acid resin (A) from the viewpoint of obtaining a sufficient flame retardant improvement effect, and 0.5 parts by mass or more is required. Preferably, 1 part by mass or more is more preferable. When the aliphatic carbodiimide and the aromatic carbodiimide are used in combination, the blending amount of the aromatic carbodiimide is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, from the viewpoint of obtaining a sufficient addition effect. Part or more is more preferable. The blending ratio (mass ratio) of the aliphatic carbodiimide and the aromatic carbodiimide can be set, for example, in the range of 1/9 to 9/1, preferably in the range of 3/7 to 7/3, and 4/6 to 6/4. Can be set to a range. On the other hand, if the amount of the carbodiimide compound is too large, the effect according to the amount added cannot be obtained, so it can be set to 20 parts by mass or less, such as resin moldability, bleed resistance, production cost, etc. From the viewpoint, 10 parts by mass or less is preferable, and 5 parts by mass or less is more preferable.

  The polylactic acid resin composition according to the embodiment of the present invention may include fibers such as inorganic fibers, organic synthetic fibers, plant-derived natural fibers, and the like. Inorganic fibers are preferable from the viewpoint of heat resistance and the like, and examples of the inorganic fibers include inorganic fibers such as metal fibers, glass fibers, metal silicate fibers, inorganic oxide fibers, and inorganic nitride fibers. A fiber may be used individually by 1 type, and 2 or more types may be mixed and used for it. Two or more kinds selected from inorganic fibers, organic synthetic fibers, and plant-derived natural fibers may be mixed and used, and preferably contain at least inorganic fibers. By including fibers, it is possible to obtain the effect of preventing thermal deformation and drip suppression of the molded body. The fiber may have a circular fiber cross section, but may have a polygonal shape, an indeterminate shape, or an uneven shape. From the viewpoint of increasing the bonding area with the resin, those having irregularities with a high aspect ratio and those having a small fiber diameter are desirable. If necessary, the fibers can be subjected to a surface treatment in order to increase the affinity with the resin serving as the base material or the entanglement between the fibers. As the surface treatment method, treatment with a coupling agent such as silane or titanate, ozone or plasma treatment, or treatment with an alkyl phosphate type surfactant is effective. However, the treatment method is not particularly limited, and a treatment method that can be generally used for surface modification of the filler can be used. The average fiber length of the fibers (number average fiber length of fibers excluding crushed pieces) is preferably in the range of 0.1 mm to 20 mm, and more preferably in the range of 0.1 mm to 10 mm. Moreover, it is preferable that the fiber of the fiber length of 300 micrometers-20 mm is included. Although there is no restriction | limiting in particular in fiber content, From the point of obtaining sufficient addition effect, 1 mass% or more is preferable on the basis of the whole polylactic acid-type resin composition, 3 mass% or more is preferable, and shaping | molding of a resin composition From the viewpoint of sufficiently ensuring the property and mechanical strength, it is preferably 50% by mass or less, more preferably 30% by mass or less, for example, 1% by mass or more and 10% by mass or less. Furthermore, polyamide fibers and polyarylate fibers can be used as organic synthetic fibers.

  You may make the polylactic acid-type resin composition by embodiment of this invention contain a fluorine-containing resin. Thereby, drip resistance can be improved. The fluorine-containing resin is preferably a fiber-forming type (one that forms a fibril-like structure), and is a fluorinated polyethylene such as polytetrafluoroethylene or a tetrafluoroethylene copolymer (for example, tetrafluoroethylene / hexafluoropropylene copolymer). Coalesced). The content of the fluorine-containing resin is preferably 0.05% by mass or more, and more preferably 0.1% by mass or more, based on the whole polylactic acid resin composition, from the viewpoint of obtaining a sufficient addition effect. On the other hand, 5 mass% or less is preferable and 1 mass% or less is more preferable from points, such as manufacture (granulation) of a resin composition.

  Further, various crystal nucleating agents, impact resistance improvers, plasticizers, other resins, antioxidants, lubricants, and the like are blended within a range that does not hinder the function of the polylactic acid resin composition according to the embodiment of the present invention. May be.

  When the polylactic acid-based resin composition according to the embodiment of the present invention contains a crystalline resin, a crystal nucleating agent is added in order to further promote crystallization of an amorphous component having a low flow start temperature in molding of a molded body. It is preferable to use it. Crystal nucleating agents themselves become crystal nuclei during molding of the molded body, and act to arrange the resin's constituent molecules in a regular three-dimensional structure, so that the moldability of the molded body, shortening of molding time, mechanical strength The heat resistance can be improved. Furthermore, by promoting crystallization of the amorphous content, deformation of the molded body is suppressed even when the mold temperature during molding is high, and mold release after molding is facilitated. The same effect can be obtained even when the mold temperature is higher than the glass transition temperature Tg of the resin.

  Among the crystal nucleating agents, examples of inorganic crystal nucleating agents include talc, calcium carbonate, mica, boron nitride, synthetic silicic acid, silicate, silica, kaolin, carbon black, zinc white, montmorillonite, clay mineral, and basic carbonic acid. Magnesium, quartz powder, glass fiber, glass powder, diatomaceous earth, dolomite powder, titanium oxide, zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, boron nitride and the like can be used.

Among the crystal nucleating agents, organic crystal nucleating agents include octylic acid, toluic acid, heptanoic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, serotic acid, montanic acid, melicic acid, Organic carboxylic acids such as benzoic acid, p-tert-butylbenzoic acid, terephthalic acid, terephthalic acid monomethyl ester, isophthalic acid, isophthalic acid monomethyl ester, rosin acid, 12-hydroxystearic acid, cholic acid; alkalis of the above organic carboxylic acids (Earth) Alkali (earth) metal salts of organic carboxylic acids such as metal salts; metal salts of carboxyl group-containing polyethylene obtained by oxidation of polyethylene, metal salts of carboxyl group-containing polypropylene obtained by oxidation of polypropylene, ethylene and propylene , Butene-1, etc. Metal salts of copolymers of fins and acrylic acid or methacrylic acid, metal salts of copolymers of styrene and acrylic acid or methacrylic acid, metal salts of copolymers of olefins and maleic anhydride, styrene and High molecular organic compounds having a metal salt of a carboxyl group such as a metal salt of a copolymer with maleic anhydride; oleic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, N-oleyl palmitoamide, N- Stearyl erucamide, N, N′-ethylenebis (stearoamide), N, N′-ethylenebis-12-hydroxystearylamide, N, N′-methylenebis (stearoamide), methylol stearamide, ethylenebisoleic acid amide, Ethylene bis behenate amide, ethylene bis stearic acid amide, ethylene bis Uric acid amide, hexamethylene bis oleic acid amide, hexamethylene bis stearic acid amide, butylene bis stearic acid amide, N, N′-dioleyl sebacic acid amide, N, N′-dioleyl adipic acid amide, N, N ′ -Distearyl adipic acid amide, N'-distearyl sebacic acid amide, m-xylylene bis stearic acid amide, N, N'-distearyl isophthalic acid amide, N, N'-distearyl terephthalic acid amide, N-oleyl Oleic acid amide, N-stearyl oleic acid amide, N-stearyl erucic acid amide, N-oleyl stearic acid amide, N-stearyl stearic acid amide, dimethylol oil amide, dimethyl lauric acid amide, dimethyl stearic acid amide, etc., N, N '-Cyclohexanebis Stearamide), aliphatic carboxylic acid amides such as N-laureuil L-glutamic acid-α, γ-n-butyramide; N-butyl-N′-stearyl urea, N-propyl-N′-stearyl acid urea, N-allyl- Examples include urea compounds such as N'stearyl urea, N-phenyl-N'-stearyl urea, and N-stearyl-N'-stearyl urea.
Examples of the organic crystal nucleating agent comprising a polymer compound include 3,3-dimethylbutene, 1,3-methylbutene, 1,3-methylpentene, 1,3-methylhexene, 1,3,5,5-trimethylhexene. Polymers of 3-position branched α-olefins having 5 or more carbon atoms such as -1; polymers of vinylcycloalkanes such as vinylcyclopentane, vinylcyclohexane and vinylnorbornane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; polyglycols Acid; Cellulose compounds such as cellulose, cellulose ester and cellulose ether; Polyester; Polycarbonate.
Examples of organic crystal nucleating agents composed of phosphorus compounds include diphenyl phosphate, diphenyl phosphite, sodium bis (4-tert-butylphenyl) phosphate, and methylene phosphate (2,4-tert-butylphenyl) phosphate. Or an organic compound of phosphoric acid or phosphorous acid or a metal salt thereof.
Other organic crystal nucleating agents include sorbitol derivatives such as bis (p-methylbenzylidene) sorbitol and bis (p-ethylbenzylidene) sorbitol; cholesterol derivatives such as cholesteryl stearate and cholesteryloxysystemaramide; thioglycolic anhydride; Examples include paratoluenesulfonic acid, paratoluenesulfonic acid amide, and metal salts thereof.

  Among these, a crystal nucleating agent made of a neutral substance that does not promote polyester hydrolysis is preferable because it can suppress a decrease in molecular weight due to hydrolysis of a polylactic acid resin. In addition, from the viewpoint of suppressing the reduction in molecular weight due to the transesterification reaction of the polylactic acid resin, an ester or amide compound that is a derivative thereof is preferable to a crystal nucleating agent having a carboxy group, and a crystal nucleus having a hydroxy group. An ester or ether compound which is a derivative thereof is more preferable than an agent.

It is preferable that the crystal nucleating agent is compatible with the resin in a high-temperature molten state or finely dispersed in the resin in injection molding or the like, and precipitates or phase-separates in the molding and cooling stage in the mold and acts as a crystal nucleus. As such a crystal nucleating agent, a layered compound such as talc is preferable.
An inorganic crystal nucleating agent and an organic crystal nucleating agent may be used in combination, or a plurality of types may be used in combination.
The content of the crystal nucleating agent is preferably in the range of 0.1 to 20% by mass as a ratio with respect to the polylactic acid resin composition.

  As an impact resistance improver, a soft component may be added to the polylactic acid resin composition. Examples of the flexible component include a polymer block (copolymer) selected from the group consisting of a polyester segment, a polyether segment, and a polyhydroxycarboxylic acid segment; a polylactic acid segment, an aromatic polyester segment, and a polyalkylene ether segment are bonded to each other. A block copolymer comprising a polylactic acid segment and a polycaprolactone segment; a polymer having an unsaturated carboxylic acid alkyl ester unit as a main component; polybutylene succinate, polyethylene succinate, polycaprolactone, polyethylene Aliphatic polyesters such as adipate, polypropylene adipate, polybutylene adipate, polyhexene adipate, polybutylene succinate adipate; polyethylene glycol And its esters, polyglycerin acetate, epoxidized soybean oil, epoxidized linseed oil, epoxidized linseed oil fatty acid butyl, adipic acid aliphatic polyester, acetyl citrate tributyl, acetyl ricinoleate, sucrose fatty acid ester, sorbitan Examples thereof include plasticizers such as fatty acid ester, adipic acid dialkyl ester, and alkylphthalyl alkyl glycolate.

  Moreover, you may add a plasticizer to a polylactic acid-type resin composition as needed. As the plasticizer, those generally used as a plasticizer for polylactic acid resins and ester resins, such as diester compounds consisting only of fatty chains and diester compounds having an aromatic group, can be used. Specific examples include benzyl-2- (2-methoxyethoxy) ethyl adipate and a copolymer of triethylene glycol monomethyl ether and succinic acid.

  You may add other resin to a polylactic acid-type resin composition as needed. Examples of other resins that can be used include thermoplastic resins such as polypropylene, polystyrene, ABS, nylon, polyethylene terephthalate, polybutylene terephthalate, and polycarbonate, and alloys of these thermoplastic resins. Further, a thermoplastic resin having crystallinity, for example, polypropylene, nylon, polyethylene terephthalate, polybutylene terephthalate, alloys with these polylactic acid resins, and the like are preferable.

  Other resins include phenolic resins, urea resins, melamine resins, alkyd resins, acrylic resins such as PMMA (polymethyl methacrylate), unsaturated polyester resins, diallyl phthalate resins, epoxy resins, silicone resins, cyanate resins, Thermosetting resins such as isocyanate resins, furan resins, ketone resins, xylene resins, thermosetting polyamides, thermosetting polyamides, styrylpyridine resins, nitrile-terminated resins, addition-curable quinoxalines, and addition-curable polyquinoxaline resins Alternatively, thermosetting resins using plant raw materials such as lignin, hemicellulose, and cellulose can also be used. When using a thermosetting resin, it is preferable to use the hardening | curing agent and hardening accelerator which are required for hardening reaction.

  The polylactic acid resin composition according to the embodiment of the present invention may contain an antioxidant such as a hindered phenol or a phosphite compound, a lubricant such as a hydrocarbon wax or an anionic surfactant. 0.05-3 mass parts is preferable with respect to 100 mass parts of polylactic acid-type resin, and, as for each content of antioxidant and a lubricant, 0.1-2 mass parts is more preferable.

The polylactic acid-based resin composition according to the embodiment of the present invention includes an antistatic agent, an antifogging agent, a light stabilizer, an ultraviolet absorber, a pigment, a colorant, an antifungal agent, an antibacterial agent, a foaming agent, if necessary. A heat stabilizer, a weathering agent, a mold release agent, and a filler can be contained within a range that does not interfere with a desired effect according to the object of the present invention.
There are no particular limitations on the method of mixing the various components of the polylactic acid-based resin composition according to the embodiment of the present invention, and mixing with a known mixer such as a tumbler, ribbon blender, uniaxial or biaxial kneader, etc. , Melt mixing by an extruder, a roll or the like.

  The molded body according to the embodiment of the present invention can be obtained by molding the above-described polylactic acid resin composition by a method such as injection molding, injection / compression molding, extrusion molding, or mold molding. It is preferable to promote crystallization during the manufacturing process or after molding because a molded body excellent in impact resistance and mechanical strength can be obtained. As a method for promoting crystallization, a method of using the above crystal nucleating agent in the above range can be mentioned.

  Since such a molded article is excellent in sustained antibacterial properties and stability, it is suitable for housing equipment, facilities and equipment such as public facilities and stores, and exterior parts of electronic equipment.

The present invention will be described in more detail with reference to the following examples, but the technical scope of the present invention is not limited thereto.
In the examples, reference examples, and comparative examples, the details of the raw materials used are as follows.

Polylactic acid resin (A)
Polylactic acid resin 1: Terramac TE-4000N (trade name) manufactured by Unitika Ltd. (melting point: 170 ° C.).

Inorganic compound (B)
Inorganic compound 1: Zeomic KM10D (trade name) manufactured by Sinanen Zeomic Co., Ltd.
It is a composite of aluminosilicate and phosphoric acid that can release zinc ions and silver ions slowly.
PH of 0.1% by weight aqueous solution = 4.5;
Inorganic Compound 2: Zeomic DAW502 (trade name) manufactured by Sinanen Zeomic Co., Ltd.
A composite of aluminosilicate and zinc oxide that can release silver ions slowly.
PH of 0.1 mass% aqueous solution = 9.5.

Additive 1: Eco Promote (trade name) manufactured by Nissan Chemical Industries,
Zinc phenylphosphonate,
PH of 0.1% by weight aqueous solution = 8.0;
Additive 2: Scarlow K (trade name) manufactured by Antibacterial Research Institute, Inc.
Calcium hydroxide,
PH of 0.1% by weight aqueous solution = 12.2.

[Examples 1-7, Comparative Examples 1-3, Reference Example 1]
A hopper mouth of a continuous kneading extruder (S1 kneader (trade name) manufactured by Kurimoto Seisakusho) in which a cylinder temperature was set to 195 to 200 ° C. with a mixture obtained by dry blending the raw materials at a mass ratio shown in Tables 1 to 3 Sourced from. The screw was rotated at 150 rpm and mixed and stirred under melt shearing to obtain a resin composition.
The polylactic acid resin composition that can be made into a strand was pelletized with a pelletizer. After the pellets were dried at 100 ± 5 ° C. for 5 hours, an injection molding machine (EC20P-0.4A (trade name) manufactured by Toshiba Machine Co., Ltd., resin temperature: 200 ° C., mold surface temperature: 25 ° C.) was used. A test piece (40 × 40 × 2.0 mm) was molded.

[Confirmation of molding stability 1]
The molten mixture discharged from the die port of the extruder was determined according to the following criteria and used as an index of molding stability (molding stability 1).
◎ (good): can be easily stranded.
X (defect): The ejected material can be pulled to some extent with tweezers, but cannot be stranded.
XX (unsuitable): The ejected material decomposed violently, so it cannot even be pinched with tweezers.

[Confirmation of molding stability 2]
The molten mixture discharged from the die port of the extruder was dissolved in chloroform, and the molecular weight in terms of polystyrene was measured. For the measurement, a gel permeation chromatography apparatus (GPC apparatus) LC-10ADvp (trade name) (columns: GPC-80MC, GPC-80M, GPC-8025C) manufactured by Shimadzu Corporation was used.

Using the same continuous kneading extruder, only the polylactic acid resin is melt-kneaded under the same conditions, and the number average molecular weight of the maximum peak of each composition is based on the number average molecular weight (Mn of the maximum peak) measured after cooling in a water bath. And the ratio of the maximum peak (% by mass) was determined and judged according to the following criteria, which was used as an index of molding stability (molding stability 2).
◎ (good): No change in the number average molecular weight of the maximum peak, the ratio of the maximum peak of 98% or more,
Δ (insufficient): No change in the number average molecular weight of the maximum peak, the ratio of the maximum peak of 95% or more and less than 98%,
X (unsuitable): The number average molecular weight of the maximum peak is reduced to 50% or less of the standard.

[Evaluation of antibacterial properties]
About the test piece produced by the above method, JIS Z2801: 2010 (Staphylococcus aureus, Escherichia coli) and “Antibacterial performance test method / display and judgment standard for building materials / household equipment” established by the Japan Construction Industry Association Based on this, the antibacterial properties of the test piece (molded body) without treatment and after pretreatment were evaluated. When the antibacterial activity value is 2.0 or more, it has antibacterial properties (passes the standard), and the higher this value, the better the antibacterial properties. The test results are shown in Tables 2 and 3.

The pretreatment conditions for the antibacterial test were as follows.
1. Immersion in warm water: Immerse the specimen in warm water of 50 ± 5 ° C. for 16 hours.
2. Light irradiation: Test specimen surface is irradiated with sunshine weather meter for 16 hours.
3. Detergent treatment: Appropriate amount of toilet general neutral detergent was applied to the surface of the test piece, left at room temperature for 8 hours, washed with water, and air dried for 24 hours.

Table 1 shows the determination results of molding stability 1 and 2 of the resin composition and moldability (whether a masterbatch can be produced) for a mixture obtained by dry blending raw materials at the mass ratio shown in the table. .
Tables 2 and 3 show the antibacterial determination results in addition to the molding stability and moldability of the resin composition for the mixture obtained by dry blending the raw materials at the mass ratios shown in the table.

From the results of Examples 1 to 7, it was found that the polylactic acid-based resin composition of this example had both continuous antibacterial properties and stability.
On the other hand, in Comparative Example 1 and Comparative Example 3 in which Additive 2 (antibacterial agent: calcium hydroxide) having a pH of 12.2 in a 0.1% by mass aqueous solution was added to the polylactic acid resin, stability during molding Has been found to be insufficient and these molten mixtures cannot be stranded.
Further, Comparative Example 2 in which 0.5% by mass of additive 1 (zinc phenylphosphonate) is added to 99.5% by mass of the polylactic acid-based resin is stable in molding and antibacterial in the case of no treatment. Although it was good, the antibacterial property decreased after the pretreatment, so that it was found that the sustained antibacterial property was insufficient. This was considered to be due to the elution of zinc ions and the photooxidative degradation of phenylphosphonic acid.
From comparison between Example 1 and Reference Example 1 in which 10% by mass of the inorganic compound (B) containing zinc is added to 90% by mass of the polylactic acid-based resin (Table 1), The case of containing inorganic compound 1 having a pH of 4.5 is more stable than the case of containing inorganic compound 2 having a pH of 9.5 in a 0.1% by mass aqueous solution. It was found that it can be easily created. For example, when a small amount of an inorganic compound (B) of about 0.1 to 0.5% is directly melt-mixed with the polylactic acid resin (A), the composition of the melt mixture tends to be non-uniform, and this mixture is used. There is a risk that the antibacterial properties of the molded article to be produced will vary. In contrast, the inorganic compound (B) can be directly melt-mixed with the polylactic acid resin (A) at a high concentration of over 5% to 15% to stably obtain a high-concentration master batch that can be pelletized. If possible, by mixing and molding the pellets of this high-concentration master batch and the pellets of polylactic acid resin (A), a molded product with a uniform composition can be obtained, and a small amount of inorganic compound (B) is added directly. In this case, it is possible to reduce the possibility of occurrence of antibacterial variation for each molded body, which is a concern. Therefore, from the viewpoint of forming a master batch, it is preferable to use the inorganic compound (B) in which the pH of the 0.1% by mass aqueous solution is relatively low (preferably the pH is 4.0 to 8.0).

Claims (10)

  A polylactic acid resin composition having antibacterial properties, comprising a polylactic acid resin (A) and an inorganic compound (B) having a pH (hydrogen ion concentration) of a 0.1% by mass aqueous solution of 4.0 to 10.0 .   The polylactic acid-based resin composition according to claim 1, wherein the inorganic compound (B) is a compound having a zeolite structure.   The polylactic acid-based resin composition according to claim 1 or 2, wherein the inorganic compound (B) is a compound containing a zinc component.   The polylactic acid-based resin composition according to any one of claims 1 to 3, wherein the inorganic compound (B) is a compound containing silver ions.   The inorganic compound (B) is one compound selected from a complex of aluminosilicate and phosphoric acid, a complex of aluminosilicate and zinc oxide, or a mixture of two or more types. The polylactic acid resin composition according to claim 1.   The polylactic acid according to any one of claims 1 to 5, wherein the inorganic compound (B) is a compound having a pH (hydrogen ion concentration) of a 0.1 mass% aqueous solution of 4.0 to 8.0. Resin composition.   The content of the inorganic compound (B) is in the range of 0.1 to 15% by mass as a mass ratio of the total of the polylactic acid resin (A) and the inorganic compound (B). The polylactic acid-type resin composition as described in any one.   The content of the inorganic compound (B) is in the range of 0.1 to 8% by mass as a mass ratio of the total of the polylactic acid resin (A) and the inorganic compound (B). The polylactic acid-type resin composition as described in any one.   The molded object obtained by shape | molding the polylactic acid-type resin composition as described in any one of Claim 1 to 8.   The exterior material which consists of a molded object of Claim 9.