JP2005336414A - Resin composition and molded product therefrom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a resin composition and a molded product therefrom that have excellent impact resistance, antibacterial properties and allergy resistance. <P>SOLUTION: The resin composition and the molded product therefrom comprise at least a polylactic acid and a deproteinized natural rubber. The weight average molecular weight and melt index of the polylactic acid are preferably in the range of 80,000-250,000 and not less than 0.1, respectively. The content of proteins in the deproteinized natural rubber is preferably not more than 0.1 mass%. The mass ratio of the polylactic acid to the deproteinized natural rubber is preferably in the range of 98:2 to 80:20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a resin composition and a molded body using the same, and more particularly to a resin composition containing a plant-derived material and a molded body using the same.

  In recent years, environmental pollution due to plastic waste has become serious. For example, petroleum-derived resins such as ABS resin and PP resin generate carbon dioxide during incineration and cause global warming.

  On the other hand, polylactic acid obtained by polymerizing lactic acid produced by fermenting starch or the like has attracted high interest as a material for biodegradable plastics. Since the raw material of polylactic acid is a carbohydrate produced by plants such as starch, the amount of carbon dioxide generated between the manufacturing process and the disposal process is significantly smaller than that of petroleum-derived resins.

Since polylactic acid itself is inferior in impact resistance, attempts have been made to improve this defect by adding various additives to polylactic acid. For example, a polylactic acid resin composition comprising crystalline polylactic acid and a rubber component such as petroleum elastomer or natural rubber has been reported (for example, see Patent Document 1).
JP 2003-183488 A

  However, if the rubber component is a petroleum-based elastomer, carbon dioxide generated during incineration causes global warming. On the other hand, natural rubber derived from plants does not cause global warming if carbon dioxide is absorbed by plants even if carbon dioxide is generated by incineration. However, it has been pointed out that natural rubber causes allergies.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a resin composition having excellent impact resistance and antibacterial and antiallergic properties, and a molded body using the same. .

That is, the present invention
<1> A resin composition containing at least polylactic acid and deproteinized natural rubber.

  <2> The resin composition according to <1>, wherein the polylactic acid has a weight average molecular weight of 80,000 to 250,000.

  <3> The resin composition according to <1> or <2>, wherein a melt index of the polylactic acid is 0.1 or more.

  <4> The resin composition according to any one of <1> to <3>, wherein a mass ratio between the polylactic acid and the deproteinized natural rubber is 98: 2 to 80:20.

  <5> The resin composition according to any one of <1> to <4>, wherein the protein content of the deproteinized natural rubber is 0.1% by mass or less.

  <6> A molded body formed of the resin composition according to any one of <1> to <5>.

  According to the present invention, it is possible to provide a resin composition having excellent impact resistance and antibacterial and antiallergic properties and a molded body using the same.

  Hereinafter, the resin composition of the present invention and a molded body using the same will be described in detail.

<Resin composition>
The resin composition of the present invention contains at least polylactic acid and deproteinized natural rubber. Since polylactic acid contained in the resin composition of the present invention has antibacterial properties, a molded article using the resin composition of the present invention has antibacterial properties. The deproteinized natural rubber contained in the resin composition of the present invention is a rubber from which proteins in the natural rubber that cause allergies are removed. Therefore, the molded body using the resin composition of the present invention has antiallergic properties. Furthermore, since the resin composition of the present invention contains deproteinized natural rubber, a molded article using the resin composition of the present invention is excellent in impact resistance.

-Polylactic acid-
Polylactic acid is an aliphatic polyester obtained by polymerizing at least one of L-lactic acid (LA) and D-lactic acid (DA). Since polylactic acid has an asymmetric carbon in the main chain, it is a crystalline homopolymer consisting only of L-lactic acid, a crystalline homopolymer consisting only of D-lactic acid, and an amorphous property consisting of a random copolymer of LA and DA. There are polymers and polymers with intermediate optical purity. By changing the ratio of L-lactic acid and D-lactic acid, the crystallinity and melting point of polylactic acid can be freely adjusted. The polylactic acid used in the present invention preferably has a ratio of L-lactic acid or D-lactic acid of 98% or more.

  If the ratio of L-lactic acid or D-lactic acid in polylactic acid is 98% or more, the crystallinity of polylactic acid can be increased, and the heat resistance of polylactic acid can be increased.

  The polylactic acid may contain a monomer other than L-lactic acid and D-lactic acid within the scope of the object of the present invention.

  The weight average molecular weight of the polylactic acid is preferably 80,000 to 250,000, more preferably 100,000 to 200,000, and particularly preferably 130,000 to 160,000. If the weight average molecular weight of polylactic acid is 80,000 or more, hydrolysis of polylactic acid hardly occurs, and durability of a molded body using the resin composition of the present invention is improved. On the other hand, when the weight average molecular weight of polylactic acid is 250,000 or less, the viscosity of the resin composition is in a viscosity range suitable for injection molding, and the formation of a molded body becomes easy.

  In the present invention, the weight average molecular weight refers to a value measured by gel permeation chromatography (GPC).

  The polylactic acid has a melt index of preferably 0.1 or more, more preferably 1 or more, and particularly preferably 10 or more. When the melt index of polylactic acid is 0.1 to 15, the viscosity of the resin composition is in a viscosity range suitable for injection molding, and the formation of a molded body is facilitated.

-Deproteinized natural rubber-
In the present invention, deproteinized natural rubber refers to rubber from which most of the protein contained in raw rubber has been removed. As a method for removing protein, a method of sufficiently washing latex collected from rubber trees can be used. Specifically, (i) agglomeration of rubber particles in highly diluted latex, (ii) separation of concentrated latex by centrifuging highly diluted latex, (iii) dialysis of latex, etc. Is mentioned.

  As another method, (a) the protein is decomposed by bacteria or enzymes, (b) the alkali is added to the latex and heated to decompose the protein, and (c) the soap is adsorbed on the rubber particles. For example, a method of releasing a protein that is released. You may combine these methods suitably.

  The protein content of the deproteinized natural rubber is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and particularly preferably 0.02% by mass or less. In the present invention, the protein content refers to a value obtained by multiplying the nitrogen content determined by the Kjeldahl method by 6.25.

-Production of resin composition-
The resin composition of the present invention comprises polylactic acid, deproteinized natural rubber, and fillers, ultraviolet absorbers, stabilizers, antioxidants, plasticizers, anti-coloring agents, mold release agents, coloring agents, if necessary. It can be produced by melt-mixing various additives such as antibacterial agents, lubricants, nucleating agents and electrostatic agents.

  The mass ratio of polylactic acid and deproteinized natural rubber contained in the resin composition of the present invention is preferably 98: 2 to 80:20, and more preferably 95: 5 to 85:15. If the mass ratio of polylactic acid and deproteinized natural rubber is 98: 2 to 80:20, the impact resistance and strength of the molded body using the resin composition of the present invention can be made sufficient.

  The mixing apparatus used for the production of the resin composition is not particularly limited, but a Banbury mixer, a twin screw extruder, etc. are preferable, and those that can be continuously processed are industrially advantageous and preferable.

  In order to melt and mix polylactic acid, deproteinized natural rubber, and various additives used as necessary, it is preferable to mix at a temperature as low as possible in order to prevent deterioration and alteration of the polymer. For example, the temperature is 210 ° C. or lower, preferably 190 ° C. or lower, and the time is 20 minutes or less, preferably 10 minutes or less. Further, after kneading a composition having a high rubber content of 40 to 70% by mass, it may be kneaded with polylactic acid in an amount satisfying the above-mentioned predetermined mass ratio.

  It is preferable to add a filler to the resin composition of the present invention in order to adjust fluidity and improve heat resistance.

  Specific examples of the filler include, for example, aluminum oxide, calcium carbonate, titanium oxide, barium sulfate, metal fibers, carbon fibers, aramid fibers, glass fibers, asbestos, potassium titanate whiskers, wollastonite, glass flakes, and glass beads. , Talc, mica, clay and the like. The preferable addition amount of the filler is 5 to 20 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  From the viewpoint of preventing photodegradation of the resin, it is preferable to add an ultraviolet absorber to the resin composition of the present invention. As said ultraviolet absorber, a benzophenone type ultraviolet absorber, a cyanoacrylate type ultraviolet absorber, a benzotriazole type ultraviolet absorber, a salicylate type ultraviolet absorber etc. can be used, for example.

  Specific examples of the benzophenone ultraviolet absorber include 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-m-octoxy-benzophenone, and 2,4-dihydroxy. Examples include benzophenone.

  Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3-diphenyl acrylate, 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate, and the like.

  Specific examples of the benzotriazole ultraviolet absorber include, for example, 2- (2′-hydroxy-3 ′, 5′-dicumylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-diamil). Phenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2,2′-methylenebis [4 -(1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, 2- (2′-hydroxy-3′-dodecyl-5′-methyl) Eniru) benzotriazole, and the like.

  Examples of the salicylate ultraviolet absorber include 4-t-butylphenyl salicylate, phenyl salicylate, p-octylphenyl salicylate, and the like.

  The preferable addition amount of the said ultraviolet absorber is 0.0001-5 mass parts with respect to 100 mass parts of total amounts of polylactic acid and deproteinized natural rubber.

  From the viewpoint of improving the hydrolysis resistance, it is preferable to add a stabilizer to the resin composition of the present invention. As said stabilizer, an epoxy-type stabilizer etc. are used, for example. Specifically, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate is preferable as the epoxy stabilizer. A preferable addition amount of the stabilizer is 0.0001 to 5 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  From the viewpoint of preventing oxidation of the resin, it is preferable to add an antioxidant to the resin composition of the present invention. Examples of the antioxidant include phosphorus stabilizers, epoxy stabilizers, hindered phenol antioxidants, sulfur stabilizers, and the like.

  As phosphorus stabilizers, for example, those commercially available from various stabilizer manufacturers as antioxidants can be used. Specifically, phenyl diisodecyl phosphite, phenyl di (tridecyl) phosphite, triphenyl phosphite, diphenyl Nonyl phosphite, tris (tridecyl) phosphite, dibutyl hydrogen phosphite, trilauryl trithiophosphite, tris (2,4-di-t-butylphenyl) phosphite, trisnonylphenyl phosphite, diphenylisooctyl phosphite, 2,2′-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, diphenylisodecyl phosphite, diphenylmono (tridecyl) phosphite, 2,2′-ethylidenebis (4,6-di-) t-Buchi Phenol) fluorophosphite, tris (2-ethylhexyl) phosphite, tris (isodecyl) phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4′-biphenylenediphosphonite, 4,4 ′ -Isopropylidene diphenol alkyl (C12-C15) phosphite, 4,4'-butylidenebis (3-methyl-6-t-butylphenyl) ditridecyl phosphite, bis (2,4-di-t-butylphenyl) Pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, phenyl- Bisphenol A pentaeryth Tall diphosphite, tetraphenyldipropylene glycol diphosphite, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5-tert-butylphenyl) butane, 3,4,5 6-dibenzo-1,2-oxaphosphane-2-oxide or the like can be used.

  A preferable addition amount of the phosphorus stabilizer is 0.0001 to 5 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  Examples of the epoxy stabilizer include phenyl glycidyl ether, epoxidized soybean oil, allyl glycidyl ether, epoxidized linseed oil, 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, and the like.

  Examples of the hindered phenol antioxidant include 2,6-di-t-butyl-4-hydroxymethylphenol and n-octadecyl-3- (3 ′, 5′-di-t-butyl-4-hydroxy). Phenyl) propionate, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2'-methylenebis (4-methyl-6-t-butylphenol), etc. Can be mentioned.

  Examples of the sulfur stabilizer include distearyl 3,3'-thiodipropionate, dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and the like.

  A preferable addition amount of these stabilizers is 0.0001 to 5 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  It is preferable to add a plasticizer to the resin composition of the present invention in order to impart flexibility to polylactic acid.

Examples of the plasticizer include oxyacid esters, aliphatic polycarboxylic acid esters, and aliphatic polyhydric alcohol esters.

  The preferable addition amount of the plasticizer is 5 to 20 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  It is preferable to add an anti-coloring agent to the resin composition of the present invention in order to prevent oxidation of the resin and natural rubber and deterioration due to ultraviolet rays.

  Examples of coloring inhibitors include phosphites and hypophosphites. The preferable addition amount of the coloring inhibitor is 0.1 to 2 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  It is preferable to add a release agent to the resin composition of the present invention in order to prevent the resin composition from adhering to the mold.

  Release agents include ester release agents such as montanic acid wax, pentaerythritol tetrastearate, glycerin monostearate, and polyalphaolefin, silicone release agents such as methylphenyl silicone oil, and olefin release agents. Is preferred. The preferable addition amount of the mold release agent is 0.0001 to 5 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  In order to color the resin, a colorant can be added to the resin composition of the present invention. As the colorant, known pigments, dyes, decorating materials and the like can be used. Specific examples of the colorant include organic pigments such as anthraquinone, monoazo, perinone, perylene, condensed azo, isoindolinone, heterocyclic, quinacridone, thioindigo, dioxazine, and phthalocyanine. Perinone, anthraquinone, heterocyclic, thioindigo dyes, calcium carbonate, zinc oxide, barium sulfate, titanium oxide, bengara, talc, titanium yellow, iron oxide, ultramarine, cobalt blue, calcined pigment, carbon In addition to inorganic pigments such as black, special pigments such as metallic pearls, and the like, examples thereof are also included. The preferable addition amount of the colorant is 0.1 to 5 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  An antibacterial agent can be added to the resin composition of the present invention to prevent the growth of bacteria on the surface of the molded body.

  As the antibacterial agent, any of organic and inorganic antibacterial agents can be used. Organic antibacterial agents include phenolic compounds, quaternary ammonium salt compounds, fatty acid ester compounds, biguanide compounds, bronopol, anilide compounds, iodine compounds, imidazole compounds, thiazoles. Compounds, isothiazolone compounds, triazine compounds, nitrile compounds, fluorine compounds, chitosan, tropolone compounds, organometallic compounds (zinc pyrithione, OBPA) and the like. The inorganic antibacterial agent is not particularly limited as long as it is an inorganic compound supporting an antibacterial metal such as silver or copper. Examples of the inorganic compound supporting silver ions include activated alumina and silica gel. Inorganic adsorbents such as inorganic adsorbents, zeolite, calcium phosphate, zirconium phosphate, titanium phosphate, potassium titanate, hydrous bismuth, hydrous zirconium, hydrotalcite and the like can be mentioned. The preferable addition amount of the antibacterial agent is 0.1 to 1 part by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  A lubricant can be added to the resin composition of the present invention in order to improve fluidity and plasticity.

  Examples of the lubricant include montanic acid and its salt, ester or half ester, stearyl alcohol, stellar amide and ethylene wax. A preferable addition amount of the lubricant is 0.1 to 1 part by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  A nucleating agent can be added to the resin composition of the present invention in order to improve the crystallinity of polylactic acid.

  Examples of the nucleating agent include sodium bis (4-t-butylphenyl) phosphate, alkyl-substituted dibenzylidene sorbitol, sodium 2,2′-methylenebis (4,6-di-t-butylphenyl) phosphate, bis (P-methylbenzylidene) sorbitol, bis (p-ethylbenzylidene) sorbitol and the like can be mentioned. The preferable addition amount of the nucleating agent is 0.1 to 2 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

  An electrostatic agent can be added to the resin composition of the present invention in order to prevent adhesion (antistatic) of dust and the like to the molded body.

  Examples of the electrostatic agent include aliphatic alcohol phosphate salts, fatty acid salts, higher alcohol sulfate esters, sulfates of aliphatic amines and aliphatic amides, formalin-condensed naphthalene sulfone salts, aliphatic amine salts, Examples include quaternary ammonium salts, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, alkyl pyridinium salts, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, imidazoline derivatives, and the like. The preferable addition amount of the electrostatic agent is 0.1 to 2 parts by mass with respect to 100 parts by mass of the total amount of polylactic acid and deproteinized natural rubber.

<Molded body>
The molded product of the present invention is formed of the resin composition of the present invention. The molded product of the present invention can be molded using a known method such as compression molding, injection molding, extrusion molding or the like.

  Since the molded body of the present invention has antibacterial and antiallergic properties as described above, the switch is frequently touched with bare hands in a state in which the surface of the molded body is exposed without applying a surface coating such as a coating. It can be suitably used as a panel component or the like. Furthermore, the molded article of the present invention is excellent in impact resistance.

  FIG. 1 is a view showing a switch and a switch base of a power window which is an example of a molded body of the present invention. The switch 1 and the switch base 2 are formed of the resin composition of the present invention. The switch 1 and the switch base 2 are one of the places where a person frequently touches with bare hands when driving an automobile. By using the molded article of the present invention in this part, the switch 1 and the switch base 2 have antibacterial properties. It can be given and allergic to humans can be reduced.

It is the figure which showed an example of the molded object of this invention.

Explanation of symbols

1 Switch 2 Switch base

Claims (6)

  A resin composition containing at least polylactic acid and deproteinized natural rubber.   The resin composition according to claim 1, wherein the polylactic acid has a weight average molecular weight of 80,000 to 250,000.   The resin composition according to claim 1, wherein the polylactic acid has a melt index of 0.1 or more.   The resin composition according to any one of claims 1 to 3, wherein a mass ratio of the polylactic acid and the deproteinized natural rubber is 98: 2 to 80:20.   The resin composition according to any one of claims 1 to 4, wherein the protein content of the deproteinized natural rubber is 0.1% by mass or less.   The molded object formed with the resin composition of any one of Claims 1 thru | or 5.

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