Polylactic acid resin composition

Abstract

To provide a polylactic acid resin composition that is excellent in characteristics caused by a filler, which is excellent in characteristics such as impact resistance, and productivity in molding (for example, molding cycle shortening), and a method for producing the same.SOLUTION: A polylactic acid resin composition contains a polylactic acid-based resin, a filler, an impact-resistant improver, a filler dispersion agent and / or a polymer for filler dispersion, wherein a content ratio of the filler in the polylactic acid resin composition is 20 wt.% to 60 wt.%, and a content ratio of the impact-resistant improver in the polylactic acid resin composition is 5 wt.% to 50 wt.%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polylactic acid resin composition.

Background Art

[0002] Polylactic acid is a plant-derived resin and is known as a biodegradable resin. Polylactic acid may be used after crystallization for improving heat resistance, but the polylactic acid has problems such as a slow crystallization rate and low productivity during molding, for example, a long molding cycle in injection molding.

[0003] In general, attempts have been made to blend various fillers into a resin composition to obtain a molded article with improved properties. Blending a filler at a high concentration is very difficult due to production problems (for example, a feed neck when charging the filler into a kneader), problems with filler dispersibility, etc. For example, in Patent Document 1, although it is disclosed that a resin composition is obtained by mixing polylactic acid and a filler, even when the blending amount of the filler is about 30% by weight, it is not easy to stably perform melt kneading with high productivity due to the feed neck.

[0004] Furthermore, the polylactic acid resin composition inherently has problems with impact resistance due to the properties of polylactic acid, and there is also a problem that the impact resistance further decreases when a filler is blended at a high concentration.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, in a conventional polylactic acid resin composition in which it is difficult to contain a filler at a high concentration, there is a problem that the properties attributed to the filler (for example, rigidity, heat resistance, shape stability) are not sufficiently exhibited. The present invention has been made to solve this problem, and an object thereof is to provide a polylactic acid resin composition excellent in properties attributed to a filler, excellent in properties such as impact resistance, and excellent in productivity during molding (for example, shortening of the molding cycle), and a method for producing the same.

Means for Solving the Problem

[0007] The polylactic acid resin composition of the present invention is a polylactic acid resin composition containing a polylactic acid-based resin, a filler, an impact modifier, and a filler dispersant and / or a polymer for filler dispersion, wherein the content ratio of the filler in the polylactic acid resin composition is 20% by weight to 60% by weight, and the content ratio of the impact modifier in the polylactic acid resin composition is 5% by weight to 50% by weight. In one embodiment, the impact modifier is at least one selected from the group consisting of an aliphatic polyester-based resin, an aliphatic-aromatic polyester-based resin, a polyvinyl alcohol-based resin, and natural rubber. In one embodiment, the filler dispersant is at least one selected from the group consisting of a polyhydric alcohol fatty acid ester, a fatty acid amide, a polyglycerin fatty acid ester, a condensed hydroxy fatty acid, and an alcohol ester of a condensed hydroxy fatty acid. In one embodiment, the polymer for filler dispersion is at least one selected from the group consisting of a polyolefin-based resin, a polystyrene-based resin, a polyvinyl alcohol-based resin, a polyalkylene glycol-based resin, a polyvinyl pyrrolidone-based resin, a polyester-based resin, a polyamide-based resin, an acrylic-based resin, a urethane-based resin, an epoxy-based resin, and a water-soluble polysaccharide. In one embodiment, the polymer for filler dispersion is at least one selected from the group consisting of a polyvinyl alcohol-based resin, a polyalkylene glycol-based resin, a polyvinyl pyrrolidone-based resin, and a water-soluble polysaccharide. In one embodiment, the total content ratio of the filler dispersant and the polymer for filler dispersion in the polylactic acid resin composition is 0.1% by weight to 30% by weight. In one embodiment, the filler is at least one selected from talc and mica. In one embodiment, the polylactic acid resin composition further contains a hydrolysis inhibitor. In one embodiment, the hydrolysis inhibitor is a compound having one or more functional groups selected from the group consisting of a carbodiimide group, an oxazoline group, and an epoxy group. According to another aspect of the present invention, a method for producing the polylactic acid resin composition is provided. This production method includes melt-kneading a polylactic acid resin, a filler granulate, and an impact resistance improver, wherein the filler granulate contains the filler and the filler dispersant and / or the polymer for filler dispersion, and in the filler granulate, the content ratio of the filler is 80 parts by weight to 99.9 parts by weight with respect to 100 parts by weight of the filler granulate. According to still another aspect of the present invention, an injection molded article is provided. This injection molded article is formed from the polylactic acid resin composition. According to still another aspect of the present invention, an extruded molded article is provided. This extruded molded article is formed from the polylactic acid resin composition. According to still another aspect of the present invention, a sheet-shaped shaped article is provided. This sheet-shaped shaped article is formed from the polylactic acid resin composition.

Effects of the Invention

[0008] According to the present invention, a polylactic acid resin composition excellent in filler-derived properties, excellent in properties such as impact resistance, and excellent in productivity (for example, shortening of the molding cycle) during molding, and a method for producing the same can be provided.

Modes for Carrying Out the Invention

[0009] A. Polylactic acid resin composition A-1. Overview of the polylactic acid resin composition The polylactic acid resin composition of the present invention contains a polylactic acid-based resin, a filler, an impact modifier, and a filler dispersant and / or a polymer for filler dispersion. The filler content ratio in the above polylactic acid resin composition is 20% by weight to 60% by weight. Also, the content ratio of the impact modifier in the polylactic acid resin composition is 5% by weight to 50% by weight. In this specification, the content ratios of the components in the polylactic acid resin composition, including the "filler content ratio in the polylactic acid resin composition" and the "content ratio of the impact modifier", are weight ratios based on the total solid content in the polylactic acid resin composition.

[0010] Since the polylactic acid resin composition of the present invention contains a filler in a high content with good uniformity, it is possible to form a molded article having excellent mechanical properties (for example, rigidity, dimensional stability (low molding shrinkage rate, low linear expansion coefficient, low warpage)) while using a polylactic acid-based resin as the main component. Also, in the above polylactic acid resin composition, it can be advantageously used from the viewpoints of heat resistance (heat distortion temperature property), appearance, colorability (capable of coloring into bright colors), filler dispersibility, and compositional uniformity. In particular, the above polylactic acid resin composition is advantageous in that it has excellent balance in rigidity, heat resistance, and impact resistance. Also, the above polylactic acid resin composition is excellent in production speed when manufactured by melt kneading.

[0011] In addition, in the above polylactic acid resin composition, the crystallization rate of the polylactic acid-based resin is fast, the moldability during injection molding is excellent, and the molding cycle can be shortened. The degree of crystallization of the polylactic acid resin composition can be evaluated by differential scanning calorimetry (DSC) measurement. Here, differential scanning calorimetry is a series of operations in which 5 to 10 mg of a sample is heated from room temperature to 200°C at a constant heating rate, held at 200°C for 5 minutes, and then cooled to room temperature at a constant cooling rate condition. The heat absorption amount of the melting of the polylactic acid crystals and the heat generation amount of the recrystallization are measured. Here, the faster the cooling rate at which the heat generation peak of the recrystallization occurs during the cooling process, or the higher the temperature range at which it occurs, the more crystallization becomes possible during the molding process, and the molding speed (molding cycle) can be increased. In the above polylactic acid resin composition, the heat generation peak derived from this crystallization is preferably 10 J / g or more, more preferably 20 J / g or more, and even more preferably 25 J / g or more in terms of polylactic acid. When the heat generation peak derived from this crystallization is 10 J / g or more in terms of polylactic acid, excellent heat resistance can be exhibited due to the progress of crystallization. Here, the polylactic acid conversion mentioned here is a value obtained by dividing the heat generation amount of the heat generation peak by the content of polylactic acid contained in the resin composition sample.

[0012] The polylactic acid resin composition of the present invention having the excellent characteristics as described above can be obtained, for example, by forming a filler granulated product containing the above filler, a filler dispersant, and / or a polymer for filler dispersion, and then mixing the filler granulated product and the polylactic acid-based resin (for example, mixing by melt kneading). By adopting such a manufacturing method, the workability of adding the filler and the filler dispersibility are significantly improved, and it becomes possible to contain the filler at a high content.

[0013] In one embodiment, a molded article formed from the above polylactic acid resin composition is provided. The flexural modulus of the molded article at 23°C is preferably 3 GPa or more, more preferably 5 GPa or more, still more preferably 7 GPa or more. The flexural modulus is measured in accordance with ISO178. The molded article can be obtained, for example, by injection molding using pellets of the polylactic acid resin composition as described below.

[0014] The heat distortion temperature of the molded article formed from the above polylactic acid resin composition under a load of 0.45 MPa is preferably 90°C or more, more preferably 100°C or more, still more preferably 110°C or more, and particularly preferably 120°C or more. The heat distortion temperature is measured in accordance with ISO75 using a dumbbell-shaped test piece (1A multi-purpose test piece).

[0015] The tensile strength of the molded article formed from the above polylactic acid resin composition at 23°C is preferably 35 MPa or more, more preferably 40 MPa or more, still more preferably 50 MPa or more. The tensile strength and the elongation at break described below are measured in accordance with ISO527 using a dumbbell-shaped test piece (1A multi-purpose test piece) under the condition of a pulling speed of 5 mm / min.

[0016] In the above polylactic acid resin composition, it is preferable that the heat generation peak of recrystallization in the cooling process occurs in a higher temperature region because the molding cycle can be shortened in the molding process. By the above-described DSC measurement, under the cooling condition of 10°C / min from a temperature of 200°C, the heat generation peak of the above recrystallization is preferably 95°C or more, more preferably 100°C or more, still more preferably 105°C or more.

[0017] A-2. Polylactic acid resin As the above polylactic acid resin, any suitable polylactic acid resin can be used. The polylactic acid resin can have properties equivalent to those of synthetic resins under normal use environments, and its usage state can also be equivalent to that of synthetic resins, and it exhibits degradability in a specific waste environment.

[0018] In addition to polylactic acid (homopolymer), the above-mentioned polylactic acid-based resin may be a copolymer containing a constituent unit derived from lactic acid. In one embodiment, the polylactic acid-based resin can be a copolymer of lactic acid and hydroxycarboxylic acid. Examples of the hydroxycarboxylic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, and the like. As the polylactic acid-based resin, a polylactic acid-based resin having a high L-lactic acid ratio is preferably used because it has a high melting point. The L-lactic acid ratio of the polylactic acid-based resin is preferably 96% or more, more preferably 98% or more, and even more preferably 98.6% or more.

[0019] The content ratio of the polylactic acid-based resin in the polylactic acid resin composition is preferably 29.8% by weight to 73% by weight, more preferably 35% by weight to 70% by weight, even more preferably 40% by weight to 68% by weight, and particularly preferably 45% by weight to 65% by weight.

[0020] A-3. Filler As the above-mentioned filler, any appropriate filler can be used according to the desired properties.

[0021] The properties and effects that can be imparted by the above-mentioned filler include, for example, weight increase or weight reduction, reinforcement (increase in rigidity, increase in elastic modulus, increase in strength), dimensional stability, molding cycle (crystallization rate), degree of crystallinity, thermal conductivity, electrical conductivity, magnetism, piezoelectricity, vibration damping, sound insulation, slidability, heat insulation, electromagnetic wave absorption, light reflection, light scattering, heat ray radiation, flame retardancy, radiation protection, ultraviolet protection, dehumidification, dehydration, deodorization, gas absorption, gas barrier, antiblocking, oil absorption, antibacterial property, biodegradation promotion, improvement of biocompatibility (improvement of the ratio of components derived from natural products), and the like.

[0022] For example, for the purpose of increasing volume, calcium carbonate, talc, silica, and clay are suitable. For the purpose of reinforcement, wollastonite, potassium titanate, zonnolite, gypsum fiber, aluminum borate, fibrous magnesium compound (MOS), aramid fiber, various fiber systems, carbon fiber (carbon fiber), glass fiber (glass fiber), talc, mica, glass flake, polyoxybenzoyl whisker, etc. are suitable. For the purpose of imparting antibacterial properties, catechin, silver ion-supported zeolite, copper phthalocyanine, etc. are suitable. For the purpose of imparting gas barrier properties, synthetic mica-based, nano-fillers of clay-synthetic mica, etc. are suitable. For the purpose of weight reduction, balloon systems such as silica balloon, glass balloon, cenosphere, perlite, shirasu balloon, etc. are suitable. For the purpose of imparting conductivity, carbon black, graphite, carbon fiber, metal powder, metal fiber, metal foil, etc. are suitable. For the purpose of imparting magnetism, various magnetic materials, various ferrite systems, magnetic iron oxide, samarium cobalt (Sm-Co), Nd-Fe-B, etc. are suitable. For the purpose of imparting thermal conductivity, alumina, AlN, BN, BeO, etc. are suitable. For the purpose of imparting piezoelectricity, barium titanate, lead zirconate titanate (PZT), etc. are suitable. For the purpose of imparting vibration damping properties, mica, graphite, potassium titanate, zonnolite, carbon fiber, ferrite, etc. are suitable. For the purpose of imparting sound insulation properties, iron powder, lead powder, barium sulfate, etc. are suitable. For the purpose of imparting slidability, graphite, hexagonal BN, molybdenum disulfide, Teflon (registered trademark) powder, talc, high molecular weight polyethylene, etc. are suitable. For the purpose of imparting electromagnetic wave absorption, electromagnetic wave absorption ferrite, graphite, charcoal powder, carbon microcoil (CMC), carbon nanotube (CNT), PZT, etc. are suitable. For the purpose of imparting light reflection and light scattering, titanium oxide, glass beads, calcium carbonate, aluminum powder, mica, etc. are suitable. For the purpose of imparting heat ray radiation, magnesium oxide, hydrotalcite, MOS, alumina, charcoal powder, etc. are suitable. For the purpose of flame retardancy, antimony oxide, aluminum hydroxide, magnesium hydroxide, zinc borate, red phosphorus, zinc carbonate, hydrotalcite, dawsonite, bromine-based flame retardant, phosphorus-based flame retardant, etc. are suitable. For the purpose of radiation protection, lead powder, barium sulfate, etc. are suitable.For the purpose of "UV protection", titanium oxide, zinc oxide, iron oxide, etc. are suitable. For the purpose of dehumidification and dehydration, calcium oxide, magnesium oxide, etc. are suitable. For the purpose of deodorization and gas absorption, zeolite, activated clay, etc. are suitable. For the purpose of antiblocking (preventing film adhesion), silica, calcium carbonate, talc, spherical fine particles (silicone or acrylic beads), etc. are suitable. For the purpose of oil absorption (printing ink absorption, quick drying property, etc.), spherical calcium carbonate, spherical zonotlite, etc. are suitable. For the purpose of water absorption, water-absorbing polymer gel, calcium oxide, magnesium oxide, etc. are suitable. For the purpose of improving bio-degree, cellulose-based materials (wood powder, wood fiber, sawdust, wood chips, newsprint, paper, flax, hemp, straw, rice husk, kenaf, jute, sisal, peanut shell, soybean hull, etc.), starch, etc. are suitable.

[0023] The size of the above filler can be any appropriate size. The particle diameter of the filler is, for example, 10 nm to 100 μm. The size of the filler can be determined by the laser diffraction method.

[0024] In one embodiment, a silicate compound is used as the above filler. As the silicate compound, for example, talc, mica, and wollastonite can be preferably used. In one embodiment, the above filler is at least one selected from talc and mica. Particularly preferably, it is talc. The above silicate compound has not only the effect of acting as a reinforcing material for the polylactic acid resin composition but also the effect of acting as a crystallization nucleating agent for polylactic acid. By using the silicate compound, the effect of increasing the achievable crystallinity of polylactic acid and simultaneously accelerating the crystallization rate can be obtained. As a result, the heat resistance of the polylactic acid resin composition can be increased, and the solidification time can be shortened, so that the molding processability can be improved.

[0025] As described above, the filler content ratio in the polylactic acid resin composition is 20% by weight to 60% by weight. The filler content ratio in the polylactic acid resin composition is preferably 25% by weight to 55% by weight, and more preferably 30% by weight to 50% by weight.

[0026] A-4. Impact Resistance Improver An impact resistance improver is an additive used to improve impact strength by compensating for the brittleness, embrittlement, notch sensitivity, and crack propagation of polylactic acid-based resins. For example, the impact resistance improver can be a rubber-like material. By dispersing the rubber material in a domain or microdomain form in the polylactic acid-based resin, impact energy can be absorbed or dissipated, and the impact resistance and / or toughness can be improved.

[0027] Examples of the impact resistance improver include aliphatic polyester-based resins (e.g., homopolymers or copolymers such as polycaprolactone, polyethylene succinate, polybutylene succinate adipate, polyhydroxyvalerate, etc., or modified products of these homopolymers or copolymers), aliphatic-aromatic polyester-based resins (e.g., block polymers or random polymers such as aliphatic carboxylic acids or hydroxy acids, aromatic dicarboxylic acids, and 1,3-propanediol), polyvinyl alcohol-based resins (e.g., polyvinyl alcohol, polyvinyl acetate, polyvinyl butyrate, ethylene-vinyl alcohol copolymers, etc.). Also, natural rubber, tochu elastomer, etc. can be used as natural-origin biodegradable resins. In one embodiment, the impact resistance improver is at least one selected from the group consisting of aliphatic polyester-based resins, aliphatic-aromatic polyester-based resins, polyvinyl alcohol-based resins, and natural rubber. These resins can be biodegradable resins. In one embodiment, polybutylene adipate terephthalate (PBAT) resin and / or amorphous polyhydroxyalkanoate (amorphous PHA) are preferably used.

[0028] In one embodiment, as the impact resistance improver, polyolefin elastomer, SEBS, SEPS, core-shell rubber, etc. can be preferably used. Core-shell rubber is rubber particles in the form of particles having a rubber core and a polymer shell. In one embodiment, the rubber has a submicron particle size from the viewpoint of imparting toughness. In addition, the polymer shell can provide adhesiveness and compatibility to the resin component (thermoplastic matrix).

[0029] The content ratio of the impact resistance improver in the polylactic acid resin composition is preferably 5% by weight to 50% by weight, preferably 10% by weight to 45% by weight, and more preferably 15% by weight to 40% by weight.

[0030] A-5. Filler Dispersant In one embodiment, the filler dispersant is a compound composed of a hydrophobic group and a hydrophilic group. The hydrophilic / hydrophobic balance can be controlled by adjusting the degree of esterification of the compound serving as the filler dispersant, the type of fatty acid (presence or absence of a hydroxyl group, saturated or unsaturated fatty acid, alkyl chain length), and the degree of polymerization. By using the filler dispersant, the dispersibility of the filler in the polylactic acid resin composition can be enhanced, and in the production of the filler granulated product described later, the productivity (discharge rate) can be improved, and the cleanability of the processing machine can also be enhanced.

[0031] Examples of the filler dispersant include fatty acids, fatty acid metal salts, fatty acid sulfonates, fatty acid amides, acrylamides, polyhydric alcohol fatty acid esters, polyglycerol fatty acid esters, etc. The filler dispersant may be used alone or in combination of two or more.

[0032] In one embodiment, the filler dispersant is at least one selected from the group consisting of polyhydric alcohol fatty acid esters, fatty acid amides, polyglycerol fatty acid esters, condensed hydroxy fatty acids, and alcohol esters of condensed hydroxy fatty acids.

[0033] The above-mentioned polyhydric alcohol fatty acid ester is an ester compound composed of a polyhydric alcohol and a fatty acid. As the polyhydric alcohol fatty acid ester, for example, esters of polyhydric alcohols such as pentaerythritol and glycerin and fatty acids having 8 or more carbon atoms (preferably 8 to 24 carbon atoms, more preferably 10 to 22 carbon atoms) are used.

[0034] The above-mentioned fatty acid amide is a compound having a structure formed by dehydration condensation of a fatty acid and ammonia or a primary or secondary amine. Examples of the above-mentioned fatty acid amide include saturated fatty acid monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide.

[0035] The above-mentioned polyglycerol fatty acid ester is an ester compound composed of polyglycerol and a fatty acid. Examples of the polyglycerol fatty acid ester include diglycerol palmitate, diglycerol stearate, diglycerol oleate, decaglycerol palmitate, decaglycerol stearate, decaglycerol oleate, and the like.

[0036] Commercially available products may be used for the above-mentioned polyglycerol fatty acid ester, condensed hydroxy fatty acid, and alcohol ester of condensed hydroxy fatty acid. Examples of commercially available products include "Tirabazole P-4", "Tirabazole VR-01", "Tirabazole VR-08" (polyglycerol fatty acid ester), "Tirabazole H-818" (alcohol ester of condensed hydroxy fatty acid), etc. manufactured by Sun Chemical Corporation. These may be used alone or in combination of two or more.

[0037] The content ratio of the above-mentioned filler dispersant in the polylactic acid resin composition is preferably 0.1% by weight to 15% by weight, more preferably 1% by weight to 10% by weight, and still more preferably 1% by weight to 5% by weight.

[0038] The total content ratio of the filler dispersant and the polymer for filler dispersion in the polylactic acid resin composition is preferably 0.1% by weight to 30% by weight, more preferably 1% by weight to 25% by weight, and still more preferably 1% by weight to 15% by weight. Within such a range, a resin composition excellent in the properties caused by the filler can be obtained, and a polylactic acid resin composition excellent in productivity and filler dispersibility can be obtained. Note that the "total content ratio of the filler dispersant and the polymer for filler dispersion" means the content ratio of the polymer for filler dispersion when the polylactic acid resin composition does not contain a filler dispersant, and means the content ratio of the filler dispersant when the polylactic acid resin composition does not contain a polymer for filler dispersion.

[0039] A-6. Polymer for Filler Dispersion The above polylactic acid resin composition may contain a polymer for filler dispersion for the purpose of enhancing the dispersibility of the filler. In addition, the polymer for filler dispersion may exhibit the effect of improving the interfacial adhesion between the filler and the polylactic acid resin.

[0040] The polymer for filler dispersion may be at least one selected from the group consisting of polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyalkylene glycol resins, polyvinyl pyrrolidone resins, polyester resins, polyamide resins, acrylic resins, urethane resins, epoxy resins, and water-soluble polysaccharides. In one embodiment, the polymer for filler dispersion is at least one selected from the group consisting of polyvinyl alcohol resins, polyalkylene glycol resins, polyvinyl pyrrolidone resins, and water-soluble polysaccharides. These resins are particularly preferably used because they are excellent in compatibility with the polylactic acid resin, not only excellent in the filler dispersion function, but also have the characteristic of biodegradability themselves.

[0041] Specific examples of the above polyvinyl alcohol-based resin as a polymer for filler dispersion include ethylene-vinyl alcohol copolymer (EVOH; Eval (registered trademark) manufactured by Kuraray Co., Ltd.), butanediol-vinyl alcohol copolymer (BVOH; Nichigo G Polymer (registered trademark) manufactured by Mitsubishi Chemical Corporation), and the like.

[0042] The above water-soluble polysaccharide means a water-soluble compound composed of long chains of monosaccharides such as glucose and mannose. In one embodiment, the water-soluble polysaccharide is a water-soluble carbohydrate composed of the binding of 10 or more monosaccharides. In one embodiment, the water-soluble polysaccharide can be a naturally-derived polymer substance. For example, water-soluble polysaccharides derived from plants (seeds, sap, fruits, etc.), seaweeds, and microorganisms can be used. Specific examples of the above water-soluble polysaccharides include pullulan, dextrin, chitosan, tamarind seed gum, guar gum, locust bean gum, gum arabic, karaya gum, pectin, cellulose, konjac mannan, soy polysaccharides, carrageenan, agar, tragacanth gum, alginic acid, xanthan gum, gellan gum, Agrobacterium succinoglycan, carboxymethyl cellulose, cationized guar gum, and the like. Among them, pullulan or dextrin is preferable, and pullulan is more preferable.

[0043] As the above polymer for filler dispersion, commercially available products may be used. Examples of commercially available products include ChemPearl (registered trademark) manufactured by Mitsui Chemicals, Inc., HYPOD (registered trademark) of The Dow Chemical Company, AQUACER (registered trademark) manufactured by BYK-Chemie Japan Co., Ltd., ZEICEN (registered trademark) manufactured by Sumitomo Seika Chemicals Co., Ltd., SIDENGROUP (registered trademark) manufactured by Siden Chemical Co., Ltd., SIDENOL (registered trademark) manufactured by Siden Chemical Co., Ltd., and the like.

[0044] The content ratio of the polymer for filler dispersion in the polylactic acid resin composition is preferably 0.1% by weight to 15% by weight, more preferably 1% by weight to 10% by weight, and still more preferably 1% by weight to 5% by weight.

[0045] A-7. Hydrolysis inhibitor The above hydrolysis inhibitor can be compounded for the purpose of enhancing the processing stability, long-term heat resistance, and long-term heat and humidity resistance of the polylactic acid resin composition. The hydrolysis inhibitor has a function of suppressing the decrease in the molecular weight of the polylactic acid-based resin and stabilizing it by trapping the carboxylic acid generated by the hydrolysis of the polylactic acid-based resin.

[0046] In one embodiment, the hydrolysis inhibitor is a compound having one or more functional groups selected from the group consisting of a carbodiimide group, an oxazoline group, and an epoxy group. The compound may be a polymer.

[0047] Examples of the compound containing the above carbodiimide group include, for example, dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, di-β-naphthylcarbodiimide, N,N'-di-2,6-diisopropylphenylcarbodiimide, 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, cyclic carbodiimide, Carbodilite (registered trademark: manufactured by Nisshinbo Chemical Co., Ltd.), or polycarbodiimide such as Stabaxol (registered trademark: manufactured by Rhein Chemie).

[0048] Examples of commercially available products of the compound having the above epoxy group include "Celloxide 2021P" manufactured by Daicel Corporation, "Denacol" manufactured by Nagase ChemteX Corporation, and "Epofrend" manufactured by Daicel Corporation.

[0049] Examples of commercially available products of the compound having the above oxazoline group include "Epocros" manufactured by Nippon Shokubai Co., Ltd.

[0050] The content ratio of the hydrolysis inhibitor in the polylactic acid resin composition is preferably 0.1% by weight to 5% by weight, more preferably 0.3% by weight to 4% by weight, and still more preferably 0.5% by weight to 3% by weight.

[0051] A-8. Other Components The above polylactic acid resin composition may further contain any appropriate other components (additives) as required. Examples of the additives include antioxidants, light stabilizers, foaming agents, ultraviolet absorbers, anti-blocking agents, heat stabilizers, antibacterial agents, compatibilizers, plasticizers, tackifiers, processing aids, lubricants, coupling agents, flame retardants, deoxidizers, colorants, and the like. The above additives can be added at any appropriate timing in the manufacturing process of the polylactic acid resin composition, for example, in the form of liquid, powder, pellet, granule, or masterbatch.

[0052] B. Method for producing polylactic acid resin composition In one embodiment, the above polylactic acid resin composition can be obtained by melt-kneading the above polylactic acid-based resin, the above filler, the above filler dispersant and / or filler-dispersing polymer, and the above impact modifier. Any appropriate method can be adopted as the melt-kneading method. For example, a kneader, Banbury mixer, roll, single-screw or multi-screw extruder with two or more screws can be used. Preferably, a twin-screw extruder is used. The melt-kneaded composition can be pelletized. In one embodiment, the melt-kneading is performed in a temperature range of 80°C to 170°C (preferably 100°C to 160°C).

[0053] In one embodiment, after obtaining a filler granulate containing the filler, the filler dispersant and / or the polymer for filler dispersion, the above-mentioned polylactic acid resin composition is obtained by melt-kneading the filler granulate, the above-mentioned polylactic acid resin, and the impact modifier. By adopting such a manufacturing method, the workability of filler addition and the filler dispersibility are remarkably improved, and it becomes possible to contain the filler at a high content. More specifically, since the above-mentioned filler granulate is remarkably excellent in the charging stability into a device such as an extruder, by using the filler granulate, the productivity (compound processing speed per hour) of the filler-containing resin composition can be dramatically improved. Further, when the filler granulate is used, the filler dispersibility and the molding processability (fluidity) are improved. Therefore, the polylactic acid resin composition obtained by using the filler granulate can be obtained by melt-kneading with low load extrusion, that is, melt-kneading in which excessive heat generation of the resin is suppressed, while containing the filler at a high concentration. As a result, the above-mentioned polylactic acid resin composition has suppressed thermal degradation of the resin and excellent mechanical performance and molding processability. The blending of the impact modifier can also be carried out in the granulation process of the filler granulate. In particular, when the impact modifier has a powder shape (for example, core-shell rubber), the impact modifier can be contained in the filler granulate.

[0054] (Filler granulate) The above-mentioned filler granulate can be manufactured by any suitable method. The above-mentioned filler granulate can be obtained, for example, by subjecting a mixture containing the above-mentioned filler, the above-mentioned filler dispersant and / or the binder component to a semi-wet granulation method. More preferably, the above-mentioned filler granulate can be obtained by subjecting a mixture containing the above-mentioned filler, the above-mentioned filler dispersant, and the binder component to a semi-wet granulation method. As the filler and the filler dispersant, those described in Item A can be used.

[0055] In the above filler granulate, the content ratio of the above filler is preferably 80 to 99.9 parts by weight, more preferably 82 to 99 parts by weight, still more preferably 85 to 98 parts by weight, particularly preferably 87 to 97 parts by weight, and most preferably 90 to 96 parts by weight, based on 100 parts by weight of the filler granulate.

[0056] In one embodiment, the polymer for filler dispersion is provided for mixing in the form of a polymer liquid (polymer solution or polymer dispersion) containing the polymer for filler dispersion.

[0057] In one embodiment, the method for producing the above filler granulate includes a mixing step of mixing the above filler with the above polymer component for filler dispersion and / or the above filler dispersant, a granulation step of granulating the mixture obtained through the mixing step to obtain a granulate precursor, and a drying step of drying the granulate precursor.

[0058] In the above mixing step, water may be further mixed. The water to be added is not particularly limited, and for example, tap water, distilled water, ion-exchanged water, hard water, soft water, etc. can be used.

[0059] The mixing amount of the above water is usually 1 to 30 parts by weight, preferably 3 to 25 parts by weight, and more preferably 5 to 20 parts by weight, based on 100 parts by weight of the filler in the filler granulate.

[0060] In the mixing step, it is preferable to blend the components at room temperature and homogenize them using any appropriate mixer. Examples of the mixer include Henschel mixer, kneader for powder (KDH, KDA, CKD, CPM) (Dalton Co.), Spartan mixer (SPM) (Dalton Co.), SP granulator (SPG) (Dalton Co.), etc.

[0061] In the mixing process, the mixing time can be set to any appropriate value according to the types of components, the type of mixer, the component mixing ratio, etc. In the mixing process, the mixing time is set so that each component is uniformly dispersed. In high-speed stirrers such as Henschel mixers and Spartan mixers, the treatment time can be 1 to 10 minutes. On the other hand, in the case of a kneader for powders, the treatment time may be several minutes to 60 minutes.

[0062] In the granulation process, the compression granulation method is preferably adopted. Also, in the granulation process, the semi-wet granulation method can be preferably adopted. Examples of the compression granulation method / semi-wet granulation method include the disk pelletizer method, the tabletting method, the briquetting method, etc. From the viewpoint of the balance between productivity and the quality of the obtained filler granules, the disk pelletizer method is preferably adopted.

[0063] A granulator using the disk pelletizer method basically has one or two disks with many holes of 2 mm to 30 mm, and a roller for pumping the raw material into the holes of the disks. The raw material supplied between the disk and the roller or between two disks is pressed into the holes of the disk as the roller rotates, and a columnar extrudate is formed. Here, the disk holes are provided with a taper, and in the process of the filler mixture passing through the holes, a compression stress is applied from the outer periphery of the die holes. The length of this tapered hole is called the effective length. The extruded granule precursor is cut by a cutter or the like on the back surface of the disk to obtain pellet-shaped filler granules. The length of the granule precursor (and as a result, the filler granules) can be adjusted by the distance between the back surface of the disk and the cutter and the rotation speed of the roller.

[0064] More specifically, examples of the disk pelletizer method include the roller-disk die method, the roller-ring die method, the double die method, the flat die method, etc. Examples of commercially available granulators using the disk pelletizer method include the disk pelletizer F series manufactured by Dalton.

[0065] As a drying method in the drying process, any appropriate method can be adopted. After the drying process, a filler granulated product from which fine powder has been removed can be obtained by means of a vibrating sieve or the like. In the drying process, any appropriate drying equipment is used. For example, a vibrating fluidized bed dryer is preferable because it can perform drying efficiently in a short time. For example, the vibrating fluidized bed dryer VDF series manufactured by Dalton can be mentioned.

[0066] In the present invention, various molded articles are provided by using the above-mentioned polylactic acid resin composition. For example, injection molded articles, extrusion molded articles, sheets, 3D printer molded articles, etc. can be provided. Further, shaped articles (vacuum molded articles, press molded articles, sheet-shaped shaped articles, etc.) can be obtained from the above-mentioned sheets.

Examples

[0067] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples in any way. In addition, parts and % are based on weight unless otherwise specified.

[0068] [Production Example 1] Production of Filler Granulated Product MB-1 20 parts by weight of a polymer for filler dispersion (polyolefin aqueous dispersion (aqueous PE dispersion); manufactured by Mitsui Chemicals, trade name "Chemipar A100"; polyolefin solid content concentration: 40% by weight; average particle diameter of polyolefin particles 4 μm; in the table, "D-1") and 3 parts by weight of a filler dispersant (polyglycerin condensed hydroxy fatty acid ester; manufactured by Taiyo Chemical Co., trade name "Chirabazole H818"; in the table, "C-1") were put into a 1 L plastic container and stirred for 20 minutes using a stirring blade at room temperature to obtain a mixture A. Next, 100 parts by weight of a filler (talc powder, manufactured by Asada Flour Milling Co., trade name "JM-300"; in the table, "B-1") was put into a kneader for powder (KDHJ-10), and while stirring the stirring blade at a rotation speed of 30 rpm, the mixture A was put into the kneader for powder. Then, a stirring treatment was performed for 6 minutes to obtain a mixture B. Mixture B was put into a disk pelletizer (manufactured by Dalton, trade name "Disk Pelletizer F-5 / 11-175") to obtain a pellet-shaped granule precursor. At this time, the pore diameter of the die was set to 3 mmφ, the thickness of the die plate was set to 15 mm, the effective length of the die hole was set to 10 mm, and the rotational speed of the roller of the disperser was set to 108 rpm. The obtained granule precursor was dried at 140 °C for 6 hours using a hot air circulation dryer to obtain a filler granule MB-1.

[0069] [Production Example 2] Production of Filler Granule MB-2 Except that 20 parts by weight of a polymer for filler dispersion (15% aqueous solution of water-soluble vinyl alcohol resin (BVOH); manufactured by Mitsubishi Chemical Corporation, trade name "Nichigo G-polymer AZF8035Q"; saponification degree 98.0 mol% or more; melting point: 172 °C; polymer concentration: 15% by weight; in the table, "D-2") was used instead of the polymer for filler dispersion (polyolefin aqueous dispersion (aqueous PE dispersion); manufactured by Mitsui Chemicals, Inc., trade name "Chemipar A100"), filler granule MB-2 was obtained in the same manner as in Production Example 1. The components used in Production Examples 1 and 2 are shown in Table 2.

[0070]

Table 1

[0071]

Table 2

[0072] <Evaluation> The filler granules obtained in Production Examples 1 and 2 were subjected to the following evaluations. The results are shown in Table 3. (1) Bulk density The bulk density (unit: kg / L) of the surface-modified filler granule was calculated by allowing the surface-modified filler granule after drying to fall naturally into a 1-liter graduated cylinder, filling it to the brim, weighing it accurately at a volume of exactly 1 liter. (2) Pellet Size Twenty surface-modified filler granules were taken out, and the average values of the length and diameter of the granular materials were measured using calipers. (3) Moisture Content The moisture content (unit: weight %) remaining in the surface-modified filler granules was measured using an infrared moisture meter (FD-660, manufactured by Kett Scientific Laboratory). (4) Disintegration Strength Measurement The disintegration stress (unit: kg) of the dried surface-modified filler granules was measured using a wooden hardness tester (manufactured by Shiro Sangyo Co., Ltd., trade name "WPF1600-B"). The measured value was the average value of 25 granules. (5) Filler Concentration in the Filler Granules 1 - 3 g of the filler granules were collected, kept in a crucible at 600 °C for 3 hours in an electric furnace, and the filler concentration (weight %) was calculated from the ash weight.

[0073]

Table 3

[0074] [Example 1] 32 parts by weight of filler granules MB-2, 63 parts by weight of polylactic acid (PLA; manufactured by NatureWorks, trade name "Ingeo 4032D"; melting point 155 - 170 °C; in the table, "A-1"), and 5 parts by weight of an impact modifier (polybutylene adipate terephthalate (PBAT) resin (manufactured by BASF, trade name "EcoFlex F Blend C1200"; in the table, "E-1")) were quantitatively introduced into a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., trade name "TEM37SS", L / D = 48) independently using weight feeders through a hopper provided at the most upstream position of the extruder, and continuously melt-kneaded (discharge: 20 kg / Hr) to obtain pellets of the resin composition. The cylinder temperature of the extruder was set to 200 °C from the middle part of the extruder and later. Also, the rotational speed of the main screw of the twin-screw extruder was set to 100 rpm. The melt-kneaded resin composition was extruded in a strand shape and cooled in a water-cooled bath to obtain pellets with a length of about 3 mm. [Examples 2 to 6 and Comparative Examples 1 to 3] Pellets of the polylactic acid resin composition were obtained in the same manner as in Example 1, except that the filler granulate, polylactic acid, impact modifier, and hydrolysis inhibitor shown in Table 4 were used in the compounding amounts shown in Table 4. Details of the polylactic acid, impact modifier, and hydrolysis inhibitor used are as shown in Table 2. In Comparative Examples 1 and 2, powdery talc ("B-1" in Table 2) was used without using a polymer for filler dispersion and a filler dispersant, and without forming a filler granulate. In these comparative examples, since a bridge of powder B-1 occurred at the supply port, it was not possible to stably produce pellets of the polylactic acid resin composition. Comparative Example 3 is an example lacking an impact modifier.

[0075]

Table 4

[0076] <Evaluation> The polylactic acid resin compositions obtained in the examples and comparative examples were subjected to the following evaluations. The results are shown in Table 5. (1) Ash content measurement (unit: wt%) 1 to 3 g of pellets of the polylactic acid resin composition were collected, held in a crucible at 600 °C for 3 hours in an electric furnace, and the ash weight was calculated. (2) Dispersibility of filler Pellets of the polylactic acid resin composition were rolled by hot pressing to form a sheet with a thickness of about 0.5 mm. Through the sheet, the remaining filler aggregates were visually observed and evaluated according to the following criteria. AA: A good dispersion state in which almost no filler aggregates are observed A: A state in which a very small amount of relatively small filler aggregates remain BB: A state in which a considerably large amount of relatively small filler aggregates remain B: A state in which large filler aggregates are present (Dispersion state ranking: AA > A > BB > B (left is good)) (3) Crystallization temperature (Tc) measurement (unit: °C) Using a differential scanning calorimeter (DSC) (DSC6220, manufactured by Hitachi High-Tech Science Corporation), 5 - 10 mg of the sample was heated from room temperature to 200°C at a constant heating rate, held at 200°C for 5 minutes, and then cooled to room temperature at a constant cooling rate of 10°C / min to measure the recrystallization temperature of the polylactic acid crystals. (4) MFR (unit: g / 10 min) In accordance with JIS K7210, the melt mass flow rate (MFR) was measured using a "Melt Indexer" manufactured by Toyo Seiki Seisakusho Co., Ltd. to evaluate the fluidity. The measurement conditions were 210°C and a load of 2.16 kg. (5) Tensile measurement In accordance with ISO 527, the tensile strength (unit: MPa) and elongation at break (unit: %) were measured under the condition of a tensile speed of 5 mm / min. Note that as the test piece for measurement, pellets of the polylactic acid resin composition were molded using an injection molding machine ("SI-80W" manufactured by Toyo Machine Metal Co., Ltd., 100-ton clamping force) at a cylinder set temperature of 200°C, a mold temperature of 110°C (both fixed side and operating side), and a cooling time of 60 seconds to obtain dumbbell-shaped test pieces (1A multi-purpose test pieces). (6) Flexural measurement A flexural test was conducted in accordance with ISO 178 to measure the flexural strength (unit: MPa) and flexural modulus. Note that the test piece for measurement was cut out from the dumbbell-shaped test piece obtained in the above tensile measurement. (7) Heat distortion temperature measurement (unit: °C) In accordance with ISO 75, the heat distortion temperature was measured under a load condition of 0.45 MPa. Note that the test piece for measurement was cut out from the dumbbell-shaped test piece obtained in the above tensile measurement. (8) Charpy impact test (unit: kJ / m 2 ) In accordance with ISO 179, the Charpy impact strength of notched test pieces formed from the polylactic acid resin composition was measured. Note that the test piece for measurement was cut out from the dumbbell-shaped test piece obtained in the above tensile measurement. (9) Injection molding time (unit: seconds) of the injection molded sheet (dumbbell test piece) In the injection molding of the dumbbell-shaped test piece (1A multi-purpose test piece) for the tensile test, in addition to a cooling time of 60 seconds, the total number of seconds obtained by adding the injection time, the holding pressure time, and the molding product ejection time was counted. (10) Appearance of the molded product The appearance state of the dumbbell-shaped test piece for the tensile test was classified into the following three categories. A: With a glossy feeling B: Showing dullness C: Showing a rough surface feeling (Appearance ranking: A > B > C (left is better)) (11) Warpage of the injection molded sheet (dumbbell test piece) The dumbbell-shaped test piece (1A multi-purpose test piece) for the tensile test was placed on a horizontal plane, the end part of the dumbbell piece was pressed against the horizontal plane, and the upward lift (unit: mm) from the horizontal plane at the opposite end was measured and classified into the following three categories. AA: Almost no upward lift is observed A: Upward lift is less than 2 mm B: Upward lift is 2 mm or more and less than 4 mm C: Upward lift is 5 mm or more (Warpage ranking: AA > A > B > C (left is better)) (12) Specific gravity The specific gravity of the resin composition was measured using a specific gravity meter (manufactured by Shin-Ko Electronics Co., Ltd., "DMA220H").

[0077]

Table 5

[0078] As shown in Table 5, the polylactic acid resin compositions of Examples 1 to 6 can form molded articles having excellent rigidity (flexural modulus) and heat distortion temperature. The comparison between Example 1 and Comparative Example 3 shows that the impact strength is improved by the addition of the impact modifier. Also, as shown by the fact that test pieces can be easily obtained by injection molding, the polylactic acid resin composition of the present invention has a high crystallization rate and improved moldability. Further, the obtained polylactic acid resin composition has high rigidity and heat resistance, and is also excellent in surface appearance (smoothness). Furthermore, according to the polylactic acid resin composition of the present invention, a molded article excellent in dimensional stability (shrinkage rate, linear expansion coefficient, low warpage) can also be formed. Furthermore, by adding a hydrolysis inhibitor, a molded article with improved hydrolysis resistance can be obtained.

Claims

1. A polylactic acid resin composition comprising a polylactic acid resin, a filler granulate containing a filler and a filler dispersant and / or a polymer for filler dispersion, and an impact resistance improver, wherein the content ratio of the filler in the polylactic acid resin composition is 20% by weight to 60% by weight, the content ratio of the impact resistance improver in the polylactic acid resin composition is 5% by weight to 50% by weight, A polylactic acid resin composition.

2. The polylactic acid resin composition according to claim 1, wherein the impact resistance improver is at least one selected from the group consisting of an aliphatic polyester resin, an aliphatic-aromatic polyester resin, a polyvinyl alcohol resin, and natural rubber.

3. The polylactic acid resin composition according to claim 1 or 2, wherein the filler dispersant is at least one selected from the group consisting of a polyhydric alcohol fatty acid ester, a fatty acid amide, a polyglycerin fatty acid ester, a condensed hydroxy fatty acid, and an alcohol ester of a condensed hydroxy fatty acid.

4. The polylactic acid resin composition according to any one of claims 1 to 3, wherein the polymer for filler dispersion is at least one selected from the group consisting of a polyolefin resin, a polystyrene resin, a polyvinyl alcohol resin, a polyalkylene glycol resin, a polyvinyl pyrrolidone resin, a polyester resin, a polyamide resin, an acrylic resin, a urethane resin, an epoxy resin, and a water-soluble polysaccharide.

5. The polylactic acid resin composition according to any one of claims 1 to 3, wherein the polymer for filler dispersion is at least one selected from the group consisting of a polyvinyl alcohol resin, a polyalkylene glycol resin, a polyvinyl pyrrolidone resin, and a water-soluble polysaccharide.

6. The polylactic acid resin composition according to any one of claims 1 to 5, wherein the total content ratio of the filler dispersant and the polymer for filler dispersion in the polylactic acid resin composition is 0.1% by weight to 30% by weight.

7. The polylactic acid resin composition according to any one of claims 1 to 6, wherein the filler is at least one selected from talc and mica.

8. The polylactic acid resin composition according to any one of claims 1 to 7, further comprising a hydrolysis inhibitor.

9. The polylactic acid resin composition according to claim 8, wherein the hydrolysis inhibitor is a compound having one or more functional groups selected from the group consisting of a carbodiimide group, an oxazoline group, and an epoxy group.

10. A method for producing a polylactic acid resin composition according to any one of claims 1 to 9, the method comprising melt-kneading a polylactic acid-based resin, a filler granulate, and an impact modifier, wherein the filler granulate contains the filler, the filler dispersant, and / or the polymer for filler dispersion, and the content ratio of the filler in the filler granulate is 80 to 99.9 parts by weight with respect to 100 parts by weight of the filler granulate. The method for producing a polylactic acid resin composition according to any one of claims 1 to 9.

11. An injection molded article formed from the polylactic acid resin composition according to any one of claims 1 to 9.

12. An extrusion molded article formed from the polylactic acid resin composition according to any one of claims 1 to 9.

13. A sheet-shaped shaped article formed from the polylactic acid resin composition according to any one of claims 1 to 9.

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