JP5954507B1 - Polylactic acid-based thermoplastic resin composition and molded article thereof - Google Patents

Abstract

[PROBLEMS] To obtain a molded product that can be molded with a practically sufficient molding cycle equivalent to that of petroleum-based plastic, and that is excellent in mechanical properties such as bending strength and elastic modulus, heat resistance, and dispersibility. A lactic acid-based thermoplastic resin composition is provided. SOLUTION: 65 to 90 parts by weight of a polylactic acid resin (A) and 35 to 10 parts by weight of a rubber reinforced resin (B) obtained by graft polymerization of one or more vinyl monomers to a rubbery polymer. 0.1 to 3 parts by weight of the nucleating agent (C), 0.1 to 40 parts by weight of the filler (D) containing cellulose, and 0.1 of the dispersing agent (E) with respect to 100 parts by weight in total. A polylactic acid-based thermoplastic resin composition containing ˜4.3 parts by weight. [Selection figure] None

Description

  The present invention relates to a polylactic acid-based thermoplastic resin composition that can shorten a molding cycle, has excellent productivity, and has improved physical properties such as mechanical properties such as heat resistance, bending strength, and elastic modulus in a well-balanced manner. Is. The present invention also relates to a molded article formed by molding this polylactic acid-based thermoplastic resin composition.

  Conventionally, as the cause of global warming, an increase in the concentration of carbon dioxide in the atmosphere has been pointed out, and the necessity of carbon dioxide emission regulations on a global scale has been advocated. Sources of carbon dioxide emissions include respiration of organisms, spoilage and fermentation by bacteria, but it is no exaggeration to say that they were brought about by economic activity that wasted oil resources after the industrial revolution by humans.

  On the other hand, effective use of plant resources that absorb and fix carbon dioxide has attracted attention as carbon neutral. In other words, there is a movement to absorb carbon dioxide by vegetation and to replace petroleum resources that are expected to be depleted in the future.

As for plastics, biomass plastics using plants as raw materials have been developed.
Initially, they are attracting a great deal of attention as environmentally friendly biodegradable resins, and polylactic acid resin (PLA) is expected to be put to practical use in order to find the same physical properties and mass productivity as petroleum-based plastics. However, polylactic acid resin has a very long molding cycle compared to existing petroleum plastics, and its improvement has been desired.

  Accordingly, various studies have been conducted on the problem of shortening the molding cycle of polylactic acid resin.

  For example, Patent Literature 1 discloses a method of promoting crystallization of a resin by blending talc or calcium carbonate as a filler. Since the crystallized resin has improved rigidity as a result of increased heat resistance, it is easy to release from the mold even when the resin temperature is higher than that of the conventional resin. As a result, the molding cycle is improved by shortening the cooling time, but it is still not sufficient compared with the mass productivity of petroleum-based plastics.

  Patent Document 2 shows the addition of a crystal nucleating agent. However, even when these crystal nucleating agents are added, there is a problem that the crystallization time is long, which is not practical.

  Patent Document 3 shows molding by the heat and cool method in which the mold temperature is raised and lowered sharply after molding, but there is a need for a special temperature control device and shortening the molding time. It cannot satisfy the recent demands and is insufficient as a general-purpose production method.

Japanese Patent Laying-Open No. 2015-81282 JP 2005-162867 A JP 2008-246594 A

  The present invention solves the above-mentioned problems in the prior art and can be molded with a practically sufficient molding cycle equivalent to that of petroleum-based plastic. Mechanical properties such as bending strength and elastic modulus, heat resistance, It is an object of the present invention to provide a polylactic acid-based thermoplastic resin composition capable of obtaining a molded product excellent in dispersibility and the like, and a molded product formed by molding this polylactic acid-based thermoplastic resin composition.

  As a result of diligent efforts to verify and improve the prior art, the present inventors can crystallize polylactic acid resin in a short time to impart heat resistance, shorten the molding cycle, flexural strength, elastic modulus The present inventors have found a resin composition that is excellent in mechanical properties such as the above, and has reached the present invention.

That is, the gist of the present invention is that a rubber-reinforced resin (B) obtained by graft polymerization of 65 to 90 parts by weight of a polylactic acid resin (A) and one or more vinyl monomers on a rubber polymer. 0.1 to 3 weights of nucleating agent (C) with respect to 100 weight parts in total of 35 to 10 weight parts (however, 100 weight parts in total of polylactic acid resin (A) and rubber-reinforced resin (B)) and parts, and cellulose scan (D) 0.1 to 40 parts by weight, dispersing agent (E) .1-4.3 polylactic acid thermoplastic resin composition containing the parts consists in.

  Another gist of the present invention resides in a molded article formed by molding the polylactic acid-based thermoplastic resin composition of the present invention.

  The polylactic acid-based thermoplastic resin composition of the present invention is excellent in balance in mechanical properties such as bending strength and elastic modulus, heat resistance, dispersibility of fillers, etc., and further improves the crystallization speed and increases the molding cycle. It is a material that can be shortened and is suitable for use as various housings and structural members that require high productivity.

  According to the present invention, by providing a practical polylactic acid-based thermoplastic resin composition as described above, the use of a polylactic acid resin that is a plant-based resin is expanded, and the practice of the philosophy of carbon neutral is promoted. It can contribute to reduction of environmental load.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the present specification, “(meth) acryl” means “acryl” A and “methacryl” B or “a copolymer containing both acrylic and methacryl” A + B.

  Further, the weight average molecular weight (Mw) of the polylactic acid resin (A) and the weight average molecular weight (Mw) of the acetone-soluble component of the rubber-reinforced resin (B) are both measured by gel permeation chromatography (GPC). What was measured by dissolving in tetrahydrofuran (THF) is shown in terms of polystyrene (PS).

[Polylactic acid resin (A)]
The polylactic acid resin (A) applied to the resin composition of the present invention can be obtained by known means such as a method of directly dehydrating condensation polymerization of lactic acid or a method of ring-opening polymerization of lactide.

  There are three types of optical isomers, L-form, D-form, and DL-form, in the polylactic acid resin, and commercially available polylactic acid resins have L-form purity close to 100%. The polylactic acid resin (A) used in 1) has an optical purity of 98% or more in the L form or D form from the viewpoint of crystallization. Moreover, the copolymer containing the other copolymerization component may be sufficient as long as the effect of this invention is not impaired.

Other copolymerization components contained in the polylactic acid resin (A) include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethano -Glycol compounds such as diol, neopentyl glycol, glycerin, pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid , Malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4, Dicarboxylic acids such as' -diphenyl ether dicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid; hydroxycarboxylic acids such as glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid Examples include acids; lactones such as caprolactone, valerolactone, propiolactone, undecalactone, and 1,5-oxepan-2-one. The content of such a copolymer component is usually preferably 30 mol% or less and more preferably 10 mol% or less in all monomer components in the polylactic acid resin (A).

  The molecular weight and molecular weight distribution of the polylactic acid resin (A) is not particularly limited as long as it can be practically processed, but the weight average molecular weight is usually 10,000 or more, preferably 50,000 or more, Furthermore, it is desirable that it is 100,000 or more. Although there is no restriction | limiting in particular about the upper limit of the weight average molecular weight of a polylactic acid resin (A), Usually, it is 400,000 or less.

  The molecular weight of the polylactic acid resin (A) can be measured by GPC (solvent THF) as described above, but when the polylactic acid is in a pellet form, it may be difficult to dissolve in THF. After dissolving in chloroform, the polymer component is precipitated using methanol, and the dried polymer component is dissolved in THF, and the molecular weight of the soluble component can be measured. Further, it can be dissolved by heating as necessary.

  Said polylactic acid resin (A) may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  Specific examples of such a polylactic acid resin include “NATUREWORKS” manufactured by Nature Works, “Levoda” manufactured by China Marine Biomaterials Co., Ltd., and any of them can be used in the present invention.

  In this invention, the compounding quantity of the polylactic acid resin (A) in a polylactic acid-type thermoplastic resin composition is 65 with respect to a total of 100 weight part of a polylactic acid resin (A) and the below-mentioned rubber-reinforced resin (B). It is the range of -90 weight part (rubber reinforcement | strengthening resin (B) is 10-35 weight part), Preferably it is 70-90 weight part (rubber reinforcement | strengthening resin (B) is 10-30 weight part), More preferably, it is 75- 85 parts by weight (the rubber-reinforced resin (B) is 15 to 25 parts by weight) is preferable from the viewpoint of carbon neutral, compound properties and heat resistance. If the blending amount of the polylactic acid resin (A) is less than this range, the object of the present invention for effectively using the polylactic acid resin (A) cannot be achieved, and if it is large, burrs and the like are likely to occur during molding, It becomes impossible to obtain a polylactic acid-based thermoplastic resin molded article under good moldability.

[Rubber reinforced resin (B)]
The rubber reinforced resin (B) used in the present invention is a vinyl monomer such as a vinyl cyanide monomer, an aromatic vinyl monomer, a (meth) acrylic acid ester monomer, etc. in a rubbery polymer. It is formed by graft polymerization of at least one kind of body, and is generally expressed by ABS, ASA, AES, MBS or the like.

  Examples of the rubbery polymer forming the rubber reinforced resin (B) include butadiene rubbers such as polybutadiene, styrene / butadiene copolymer, acrylate ester / butadiene copolymer, and styrene / isoprene copolymer. Conjugated diene rubbers: acrylic rubbers such as polybutyl acrylate, olefin rubbers such as ethylene / propylene copolymers, etc. Among these, polybutadiene rubbers, acrylic rubbers, olefins from the viewpoint of impact resistance Rubbers are preferable, and polybutadiene rubber is particularly preferable. These rubbery polymers can be used singly or in combination of two or more.

  These rubbery polymers can be used from monomers, and the structure of the rubbery polymer may take a core / shell structure. For example, a rubbery polymer having polybutadiene as the core and acrylic acid ester as the shell can be used.

  The gel content of the rubbery polymer is preferably 50 to 99% by weight, more preferably 60 to 95% by weight, and particularly preferably 70 to 85% by weight. When the gel content is within this range, the properties of the resulting polylactic acid-based thermoplastic resin composition, particularly the impact strength, can be improved.

  In order to measure the gel content of the rubber polymer, specifically, the weighed rubber polymer was dissolved in an appropriate solvent at room temperature (23 ° C.) over 20 hours, and then 100 mesh. After separating with a wire mesh, the insoluble matter remaining on the wire mesh is dried at 60 ° C. for 24 hours and then weighed. The ratio (% by weight) of the insoluble matter with respect to the rubber polymer before fractionation is determined and used as the gel content of the rubber polymer. As the solvent used for dissolving the rubbery polymer, for example, toluene is used for polybutadiene and acetone is used for polybutyl acrylate.

  The particle size of the rubbery polymer is not particularly limited, but is preferably 0.1 to 1 μm, and more preferably 0.2 to 0.5 μm. The average particle size of the rubbery polymer can be measured by an optical method before graft polymerization. Further, after graft polymerization, the average particle diameter can be calculated using a transmission electron microscope (TEM) after dyeing the rubber polymer with a dyeing agent.

  The rubber-reinforced resin (B) can be obtained by graft polymerization of 60 to 20% by weight of the vinyl monomer component capable of graft polymerization, preferably in the presence of 40 to 80% by weight of the above rubbery polymer ( However, the total of the rubber polymer and the monomer mixture is 100% by weight.) Here, if the rubbery polymer is not less than the above lower limit value, the resulting polylactic acid-based thermoplastic resin molded article has good impact resistance, and if it is not more than the above upper limit value, impact resistance, fluidity, etc. Can be prevented.

  Examples of vinyl monomer components that can be graft-polymerized to rubbery polymers include vinyl cyanide monomers, aromatic vinyl monomers, methacrylic acid ester monomers, acrylic acid ester monomers, A maleimide compound is mentioned, The said monomer can select and use 1 type (s) or 2 or more types, respectively.

  Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and acrylonitrile is particularly preferable. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, bromostyrene, and the like, and styrene and α-methylstyrene are particularly preferable. Examples of the methacrylic acid ester monomer include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and derivatives thereof. Among these, methyl methacrylate is particularly preferable. Examples of the acrylate monomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and derivatives thereof. Among these, methyl acrylate is particularly preferable. Examples of the maleimide compound include N-phenylmaleimide, N-cyclohexylmaleimide and the like.

  These monomer components may optionally contain monomers modified with functional groups. Examples of such monomers include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and itacone. An acid, fumaric acid, etc. are mentioned. These can be used individually by 1 type or in mixture of 2 or more types. The proportion of use is preferably 30% by weight or less, particularly preferably 10% by weight or less, based on 100% by weight of the total monomer components.

  As the vinyl monomer component grafted on the rubber polymer of the rubber reinforced resin (B), among the above exemplified monomers, in particular, a combination of a vinyl cyanide monomer and an aromatic vinyl monomer, A combination of a methacrylic acid ester monomer and an acrylic acid ester monomer is preferred. As a combination of a vinyl cyanide monomer and an aromatic vinyl monomer, acrylonitrile is used as the vinyl cyanide monomer, styrene is used as the aromatic vinyl monomer, and polylactic acid-based heat is obtained. This is preferable from the viewpoint of further improving the impact resistance of the plastic resin molded product. In this case, the weight composition ratio of the vinyl cyanide monomer and the aromatic vinyl monomer is preferably in the range of 20/80 to 35/65, more preferably 25/75 to 30/70. By being in this range, dispersibility and thermal stability are improved. Further, as a combination of a methacrylic ester monomer and an acrylate ester monomer, methyl methacrylate as a methacrylic ester monomer, methyl acrylate as an acrylate ester monomer, The resulting polylactic acid-based thermoplastic resin molded article is preferable in that it can further improve the impact resistance, improve the weld appearance, and further reduce the cooling time. In this case, the weight composition ratio of the methacrylic ester monomer and the acrylate ester monomer is preferably 100/0 to 50/50, and more preferably 99/1 to 80/20. By being in this range, the cooling time can be shortened while maintaining the weld appearance, and the moldability becomes good.

  The weight average molecular weight of the acetone-soluble component of the rubber reinforced resin (B) is preferably in the range of 50,000 to 600,000, more preferably 50,000 to 550,000, and still more preferably 100,000 to 450. , 000. When the weight average molecular weight of the acetone-soluble component of the rubber-reinforced resin (B) is not less than the above lower limit, the resulting polylactic acid-based thermoplastic resin molded article has sufficient impact resistance, and the above upper limit. By being below, the moldability of a polylactic acid-type thermoplastic resin composition becomes favorable. The acetone-soluble component corresponds to a polymer product of a vinyl monomer that is not graft-polymerized to a rubber polymer that is produced when a vinyl monomer is graft-polymerized to a rubber polymer. It is.

  The graft ratio of rubber-reinforced resin (B) ((acetone insoluble matter weight / rubber polymer weight-1) × 100) is preferably 15 to 120% by weight, more preferably 20 to 85% by weight. It is more preferable. When the graft ratio of the rubber reinforced resin (B) is not less than the above lower limit, the dispersibility of the rubber reinforced resin (B) and the impact strength of the resulting polylactic acid-based thermoplastic resin molded article are improved. Further, when the graft ratio is not more than the above upper limit value, the impact strength and the moldability are improved. The copolymer grafted on the rubber polymer may have a structure occluded not only inside but also inside the rubber polymer.

Graft polymerization can be performed by known emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization, and may be a method combining these polymerization methods.
At this time, the rubber content in the rubber reinforced resin (B) is preferably adjusted to be in the range of 5 to 80% by weight, particularly 10 to 70% by weight. When the content of the rubbery polymer in the rubber reinforced resin (B) is not less than the above lower limit value, sufficient impact resistance can be obtained. However, since the impact strength tends to decrease at most if the rubber-like polymer in the rubber-containing graft copolymer (B) is at most, it is preferably not more than the above upper limit value. The content of the rubbery polymer in the rubber reinforced resin (B) can be measured by using an infrared spectrometer.

  As the rubber reinforced resin (B), two or more kinds of rubber reinforced resins (B) having different polymerization methods and component compositions may be mixed and used.

[Nucleating agent (C)]
In this invention, the compounding quantity of the nucleating agent (C) in a polylactic acid-type thermoplastic resin composition is 0.1-0.1 with respect to a total of 100 weight part of a polylactic acid resin (A) and a rubber reinforced resin (B). Although it is the range of 3 weight part, Preferably it is 0.5-2.5 weight part, More preferably, it is 0.5-2 weight part from the point of heat resistant improvement. If the blending amount of the nucleating agent (C) is less than this range, the polylactic acid resin (A) cannot be crystallized quickly, and the object of the present invention is not achieved. On the other hand, if the blending amount of the nucleating agent (C) is larger than this range, the polylactic acid resin (A) is quickly crystallized, and a polylactic acid-based thermoplastic resin molded article having an excellent molding cycle cannot be obtained.

  The nucleating agent (C) that can be used in the present invention is not particularly limited, and examples thereof include organic carboxylic acid metal salts such as sodium benzoate, phenylphosphonic acid metal salts, rosin acid metal salts, phosphoric acid ester metal salts, Examples thereof include metal salts of sulfonated compounds such as phenylsulfonic acid metal salts, and organic nucleating agents such as carboxylic acid amides. In addition, a nucleating agent (C) may be used individually by 1 type, and 2 or more types may be mixed and used for it.

[Filling Material]
In the present invention, the amount of cellulose scan (D) of the polylactic acid-based thermoplastic resin composition is 0.1 to per 100 parts by weight of the polylactic acid resin (A) and the rubber-reinforced resin (B) 40 parts by weight, preferably in the range of 1 to 40 parts by weight, preferably 3 to 35 parts by weight, more preferably 5 to 30 parts by weight improves heat resistance, molding cycleability, and dispersibility. It is preferable in terms. If the blending amount of cellulose (D) is less than this range, the cooling time at the time of molding becomes long and the object of the present invention is not achieved. Further, when the blending amount of cellulose (D) is larger than this range, a polylactic acid-based thermoplastic resin molded article excellent in productivity and dispersibility cannot be obtained.

In the present invention, as a filler, it is mandatory to use a mechanical cutting and chemical purified cellulose derived from plants fibers in process (D), needle-like non-cellulose (D) if necessary (Here, “needle” refers to a so-called long shape including “fiber” and “bar”.) One or more fillers in any one of plate-like and powdery forms. You may mix and use.
Here, “cellulose” refers to a product obtained by removing hemicellulose and lignin from natural plant matter. As a requirement of “cellulose”, it is essential to remove hemicellulose and lignin. If these are not removed, for example, simple wood flour cannot improve the molding cycle, and color development such as discoloration. In some cases, the object of the present invention may not be achieved.

When any of fillers in the form of needles, plates, or powders is mixed with cellulose (D) , the other fillers may be inorganic fillers or organic fillers. Good. Specifically, examples of the inorganic filler include carbon fiber, glass fiber, talc, wollastonite, calcium carbonate, and silica. Examples of the organic filler include plant-derived fibers such as kenaf and bamboo fiber (these are not removed from hemicellulose and lignin, and are distinguished from cellulose (D)) . These other fillers may be used alone or in combination of two or more, but if the amount of these other fillers is too large, the amount of cellulose is relatively small. Since the bending strength and elastic modulus of the resulting polylactic acid-based thermoplastic resin molded article may decrease or the rate of crystallization may decrease, the object of the present invention may not be achieved. When using a filler, it is used in the range of 1 to 20 parts by weight with respect to a total of 100 parts by weight of the polylactic acid resin (A) and the rubber reinforced resin (B), and cellulose (D) is cellulose (D) . It is preferable to use 50 to 100% by weight with respect to the total amount of fillers contained so that the total of cellulose (D) and other fillers is in the range of 0.1 to 40 parts by weight .

Regarding the size of the filler containing cellulose (D) , the average particle diameter is preferably in the range of 10 to 70 μm, more preferably in the range of 13 to 65 μm, and still more preferably in the range of 15 to 60 μm. This is preferable in terms of time reduction. If the average particle size is out of the range, the cooling time becomes long and the object of the present invention may not be achieved.

The average particle diameter of the filler refers to the length of the portion where the distance of the two plates when sandwiched the filler two parallel plates is maximized, the cellulose (D) is D50 Indicates the median diameter value. In the case of a powdery (granular) filler, the particle diameter is indicated, and in the case of a needle-like filler, the length of the long part is indicated. Furthermore, in the case of a plate-like filler, it refers to the length of the longest portion of the plate surface.

Further, when used in combination of two or more fillers, it can determine the average particle size of the whole of the filler in each average particle diameter of its amount. For example, when two kinds of fillers are mixed and used, if the blending amount of one filler is d1, the average particle size is d1 ′, the blending amount of the other filler is d2, and the average particle size is d2 ′, The average particle diameter of the filler is calculated by the following formula.
Average particle diameter = (d1 × d1 ′ + d2 × d2 ′) / (d1 + d2)

Regarding the size of cellulose (D) , the average particle size is preferably in the range of 10 to 70 μm, more preferably in the range of 15 to 60 μm, and even more preferably in the range of 25 to 45 μm. Is preferable. If the average particle size is out of the range, the cooling time becomes long and the object of the present invention may not be achieved.

[Dispersant (E)]
In this invention, the compounding quantity of the dispersing agent (E) in a polylactic acid-type thermoplastic resin composition is 0.1- with respect to a total of 100 weight part of a polylactic acid resin (A) and a rubber reinforced resin (B). Although it is the range of 4.3 weight part, Preferably it is 0.1-3 weight part, More preferably, it is 0.1-2.5 weight part from the point of a heat resistant improvement and a dispersibility. If the blending amount of the dispersant (E) is smaller or larger than this range, the dispersion effect is insufficient, and the cooling time during molding may become longer, and the object of the present invention is achieved. do not do.

  The dispersant (E) that can be used in the present invention is not particularly limited, and glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene / sorbitan fatty acid ester, ethylene glycol fatty acid ester, polyethylene glycol diester. Benzoate, caprylic acid monoglyceride diacetate, esters such as montanic acid ester, amide compounds such as ethylene bis fatty acid amide, ethylene bis stearic acid amide, higher fatty acid polyamide, zinc stearate, magnesium stearate, lithium stearate, stear Examples thereof include metal salts such as calcium phosphate, zinc phosphate, magnesium phosphate, lithium phosphate, and calcium phosphate, and plant-derived oils such as hydrogenated castor oil. Ester, calcium phosphate is preferred.

  In addition, a dispersing agent (E) may be used individually by 1 type, and 2 or more types may be mixed and used from a viewpoint of shortening of cooling time, and 1 type or more and other than that of metal salt. It is preferable to use a mixture of one or more dispersants. In particular, it is preferable to use glycerin fatty acid ester and calcium phosphate in combination because of shortening of cooling time and excellent weld appearance.

  Thus, when using together 1 or more types of metal salt, and 1 or more types of other dispersing agents, the ratio of the metal salt to the sum total of a dispersing agent (E) is 5 to 50 weight%, especially 7 to 35 weight%. From the viewpoint of hydrolysis resistance, it is preferable to use it as follows.

[Other ingredients]
The polylactic acid-based thermoplastic resin composition of the present invention includes the above-mentioned polylactic acid resin (A), rubber-reinforced resin (B), nucleating agent (C), filler containing cellulose (D) , and dispersing agent (E). In addition, various additives and other resins can be blended. In this case, various additives include known antioxidants, ultraviolet absorbers, lubricants, plasticizers, stabilizers, mold release agents, antistatic agents, colorants (pigments, dyes, etc.), flame retardants (halogen-based flame retardants). 1 type, or 2 or more types, such as a flame retardant, a phosphorus flame retardant, an antimony compound, etc.), a drip inhibitor, an antibacterial agent, an antifungal agent, a silicone oil, a coupling agent, an anti-hydrolysis agent.

  Other resins include rubber-reinforced styrene resins such as HIPS resin, AS resin, polystyrene resin, polycarbonate resin, nylon resin, methacrylic resin, polyvinyl chloride resin, polybutylene terephthalate resin, polyethylene terephthalate resin, Examples include polyphenylene ether resin, polyethylene resin, polyethylene naphthalate resin, polypropylene resin, polypropylene terephthalate resin, polyphenylene sulfide resin, polyacetal resin, polyimide resin, phenol resin, melamine resin, silicone resin, unsaturated polyester resin, and epoxy resin. Moreover, what blended these 2 or more types may be sufficient, and you may mix | blend the said resin modified | denatured with the compatibilizer, the functional group, etc. further.

  However, in the polylactic acid-based thermoplastic resin composition of the present invention, the above-mentioned other resins are 50 parts by weight or less, particularly with respect to 100 parts by weight of the total of the polylactic acid resin (A) and the rubber-reinforced resin (B). 30 parts by weight or less is preferable in terms of effective use of the polylactic acid resin (A).

[Production and molding of polylactic acid-based thermoplastic resin composition]
There is no restriction | limiting in particular as a method of pelletizing the polylactic acid-type thermoplastic resin composition of this invention, For example, although a twin-screw extruder, a Banbury mixer, a heating roll, etc. can be used, especially by a twin-screw extruder. Melt kneading is preferable, and if necessary, resin and other additives can be blended by side feed or the like.

  The polylactic acid-based thermoplastic resin composition of the present invention can be molded into various molded products by ordinary molding methods such as injection molding, blow molding, sheet molding, vacuum molding, etc. Molding is preferred.

  There are no particular restrictions on the use of the resulting molded product, but for home appliances, white goods such as refrigerators and washing machines, housings for mobile phones, charging stands, etc. It can be suitably used for a cover, a floor box and the like.

  In addition, when preparing each component of the polylactic acid-based thermoplastic resin composition of the present invention, or when mixing, kneading, or molding these components, the resin waste, etc. generated as it is or in some cases is crushed. Thus, it can be subjected to a melt regeneration process. In this case, it can be recovered during molding, but it can also be recovered separately and used as a raw material in the above-described pellet manufacturing process.

Hereinafter, the present invention will be described more specifically with reference to synthesis examples, examples, reference examples, and comparative examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Absent.
In the following, “part” means “part by weight”.

The weight average molecular weight was measured by a standard PS (polystyrene) conversion method using Tosoh Co., Ltd. product: GPC (gel permeation chromatography, solvent; THF). The average particle diameter of the rubber polymer was determined by a dynamic light scattering method using Nikkiso Co., Ltd .: Microtrac Model: 9230UPA.
The weight composition ratio of the monomer was determined using FT-IR manufactured by Horiba Ltd.

[Polylactic acid resin (A)]
Polylactic acid resin (a-1): Polylactic acid resin (L-form / D-form = 98/2 (weight ratio),
(Weight average molecular weight = 140,000, melting point = 171 ° C.)

[Rubber reinforced resin (B)]
<Synthesis Example 1: Production of rubber-containing graft copolymer (b-1)>
A rubber-containing graft copolymer was synthesized by the emulsion polymerization method with the following composition.

[Combination]
Styrene (ST) 25 parts Acrylonitrile (AN) 10 parts Polybutadiene latex 65 parts (as solids)
Disproportionated potassium rosinate 1 part Potassium hydroxide 0.03 part Tertiary decyl mercaptan (t-DM) 0.04 part Cumene hydroperoxide 0.3 part Ferrous sulfate 0.007 part Sodium pyrophosphate 0.1 Part Crystalline glucose 0.3 part Distilled water 190 part

  An autoclave is charged with distilled water, disproportionated potassium rosinate, potassium hydroxide and polybutadiene latex (gel content 80% by weight, average particle size 0.3 μm), heated to 60 ° C., ferrous sulfate, sodium pyrophosphate Crystalline glucose was added and ST, AN, t-DM and cumene hydroperoxide were continuously added over 2 hours while maintaining the temperature at 60 ° C., and then the temperature was raised to 70 ° C. and maintained for 1 hour to complete the reaction. . An antioxidant was added to the ABS latex obtained by this reaction, then coagulated with sulfuric acid, sufficiently washed with water, and dried to obtain an ABS graft copolymer (b-1).

<Synthesis Example 2: Production of rubber-containing graft copolymer (b-2)>
In the raw material blend of Synthesis Example 1, 50 parts (as a solid content) of polybutadiene (average particle size 0.3 μm) having a gel content of 97% by weight as a rubbery polymer and 37 parts of styrene (ST) as a monomer Graft polymerization was carried out in the same manner as in Synthesis Example 1 except that 13 parts of acrylonitrile (AN) were reacted with each other to obtain an ABS graft copolymer (b-2).

<Synthesis Example 3: Production of rubber-containing graft copolymer (b-1-3)>
In the raw material formulation of Synthesis Example 1, 60 parts (as solid content) of polybutyl acrylate (gel content 65% by weight, average particle size 0.34 μm) was used as the rubbery polymer, and methyl methacrylate ( Graft copolymerization was carried out in the same manner as in Synthesis Example 1 except that 36 parts of MMA and 4 parts of methyl acrylate (MA) were reacted to obtain a graft copolymer (b-3).

The rubber content, the weight composition ratio of the monomer, the graft ratio, and the weight-average molecular weight of the acetone-soluble component of the rubber-containing graft copolymer produced in Synthesis Examples 1, 2, and 3 were measured. there were.
Rubber-containing graft copolymer (b-1): rubber content = 66.2% by weight
AN / ST = 28/72
Graft ratio = 40% by weight
Weight average molecular weight (Mw) = 154,000
Rubber-containing graft copolymer (b-2): rubber content = 52.4% by weight
AN / ST = 26/74
Graft ratio = 57% by weight
Weight average molecular weight (Mw) = 145,000
Rubber-containing graft copolymer (b-3): rubber content = 62.3 wt%
MMA / MA = 90/10
Graft ratio = 35% by weight
Weight average molecular weight (Mw) = 70,000

[Other additives]
About the nucleating agent (C), the filler , and the dispersing agent (E), the following were used.

<Nucleating agent (C)>
Nucleating agent (c-1): “Eco Promote PPA-ZN” (Zinc Phenylsulfonate (II)) manufactured by Nissan Chemical Co., Ltd.

<Filler >
Filler (d-1): “W-100GK” manufactured by Nippon Paper Industries Co., Ltd. (cellulose average particle diameter: 37 μm mechanical cutting)
Filler (d-2): “W50GK” manufactured by Nippon Paper Industries Co., Ltd. (cellulose average particle size: 45 μm mechanical cutting)
Filler (d-3): “W400G” manufactured by Nippon Paper Industries Co., Ltd. (cellulose average particle size 25 μm chemical treatment)
Filler (d-4): “W-100Y” manufactured by Nippon Paper Industries Co., Ltd. (cellulose average particle size 37 μm chemical treatment)
Filler (d-5): “TP-A25” manufactured by Fuji Talc Kogyo Co., Ltd. (talc (plate), average particle size 5 μm, plate aspect ratio 2.0)
Filler (d-6): “Wood Floor 12020” (wood flour, average particle size 117 μm) manufactured by AMERICA WOOD FIBERS

<Dispersant (E)>
Dispersant (e-1): “VR-02” manufactured by Taiyo Kagaku Co., Ltd. (glycerin fatty acid ester surfactant)
Dispersant (e-2): “HAP-08NP” (calcium phosphate) manufactured by Maruo Calcium Co., Ltd.

[Production and evaluation of polylactic acid-based thermoplastic resin composition pellets]
Each of the above components were mixed at the blending ratios shown in Tables 1 and 2, and further mixed with 0.3 parts of “Carbodilite HMV-8CA” manufactured by Nisshinbo Co., Ltd. as a stabilizer. Pellets of a polylactic acid-based thermoplastic resin composition were prepared by melting and mixing with a shaft extruder (“TEX-30α” manufactured by Nippon Steel Works) and pelletizing.

These resin pellets were molded at 200 to 220 ° C. with a 2 ounce injection molding machine (manufactured by Toshiba Corporation), and the bending strength, flexural modulus, and heat resistance (deflection temperature under load) were measured by the following methods.
Bending strength (MPa): ISO 178 (normal temperature)
Flexural modulus (MPa): ISO 178 (normal temperature)
Deflection temperature under load (° C): ISO 75 (measurement load 0.45 MPa)

  In addition, the cooling time was examined by the following method, and productivity and dispersibility were evaluated.

  Cooling time: When the resin pellets are molded at 200 to 220 ° C. with a 2 ounce injection molding machine (manufactured by Toshiba Corporation), the molded product is removed from the mold after the mold cooling is started after the pressure holding is completed. The time until was the cooling time.

Productivity: When powder raw material is compounded at 200-220 ° C with a twin-screw extruder (manufactured by Nippon Steel), (1) the shelfability of the raw material in the hopper, (2) the strand take-up property, ( 3) Productivity was defined as the cutting performance with a pelletizer. The number of bad results among the items (1) to (3) was evaluated according to the following criteria, and ◎ and ○ were judged to be practical.
◎: Number of hits among items (1) to (3) above: 0
○: Number of hits among items (1) to (3) above: 1
Δ: Number of hits among items (1) to (3) above: 2
×: Number of hits among items (1) to (3) above: 3

Dispersibility: A surface appearance state (unevenness) of a molded product obtained by molding with an injection molding machine (manufactured by Nippon Steel) was evaluated as dispersibility according to the following criteria, and ◎ and ○ were judged to be practical.
A: There is no unevenness in the surface appearance
○: Some irregularities in the surface appearance
×: Unevenness on the entire surface appearance

[Examples, Reference Examples and Comparative Examples]
Tables 1 and 2 show the results of Examples 1 to 11, Reference Examples 1 and 2, and Comparative Examples 1 to 8.

[Discussion]
As is clear from Tables 1 and 2, the polylactic acid-based thermoplastic resin compositions of Examples 1 to 11 that satisfy the requirements of the claims of the present invention have a short molding cycle and are excellent in mechanical properties, heat resistance, and the like. A molded product can be obtained.

On the other hand, in Comparative Example 1 not including the nucleating agent (C), the cooling time is long and the heat resistance is remarkably inferior. Conversely, even in Comparative Example 2 containing a large amount of the nucleating agent (C), the cooling time is not improved and the heat resistance is remarkably inferior. In Comparative Example 3 does not contain a filler, cooling time is long, poor in heat resistance. Conversely, in Comparative Example 4 contains much filler, improvement of the cooling time is observed, not be practical since the dispersibility and productivity is lowered. In Comparative Example 5 which does not contain the dispersant (E), the dispersion effect is insufficient. Conversely, even in Comparative Example 6 containing a large amount of the dispersant (E), the dispersion effect is insufficient. In either case, the cooling time is long. Even if a filler is used as in Comparative Examples 7 and 8, if cellulose (D) is not used by adding talc or wood powder alone, the cooling time cannot be shortened and the heat resistance is low. In Reference Example 1, the polylactic acid resin (A) is small, the ratio of the rubber-reinforced resin (B) is large, and the crystallization of the polylactic acid resin (A) is inhibited, resulting in a long cooling time. Yes. In Reference Example 2, a large amount of polylactic acid resin (A) results in a longer cooling time required for crystallization.

  The polylactic acid-based thermoplastic resin composition of the present invention has a short molding cycle and is excellent in productivity, and the molded product is excellent in the balance of mechanical properties such as heat resistance, bending strength and elastic modulus. The molded product formed by molding the polylactic acid-based thermoplastic resin composition of the present invention is a material suitable for use as, for example, various housings and structural members, and is used for various uses according to market needs. In addition to its very high industrial utility, it is also effective in reducing environmental burdens.

Claims (3)

Total of 65 to 90 parts by weight of polylactic acid resin (A) and 35 to 10 parts by weight of rubber reinforced resin (B) obtained by graft polymerization of one or more vinyl monomers to a rubbery polymer 100 parts by weight (however, the polylactic acid resin (a) and rubber-reinforced resin (B) total 100 parts by weight of a) with respect to, nucleating agent (C) and 0.1 to 3 parts by weight, cellulose scan (D) The polylactic acid-type thermoplastic resin composition containing 0.1-40 weight part and a dispersing agent (E) 0.1-4.3 weight part.   2. The polylactic acid-based thermoplastic resin composition according to claim 1, wherein the rubbery polymer is one or more selected from the group consisting of a polybutadiene rubber, an acrylic rubber, and an olefin rubber. Claim 1 or 2 molded article obtained by molding the polylactic acid thermoplastic resin composition according to.