JP2008101096A - Polylactic acid-based resin composition, and molded product thereof and method for producing the molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid-based resin composition excellent in both heat resistance and impact resistance, and to provide a molded product obtained using the composition and a method for producing the molded product, respectively. <P>SOLUTION: The polylactic acid-based resin composition comprises (A) a polylactic acid-based polymer, (B) a pulverized baked scallop shell product and (C) kaolin; wherein, based on 100 mass% of the whole polylactic acid-based resin composition, the component A content, the component B content and the component C content are 30-85 mass%, 5-40 mass% and 5-50 mass%, respectively. The molded product is obtained by the following process: A dispersion with the components A, B and C in a solvent is prepared, and then cast in a mold, and subsequently the solvent is removed, followed by making a molding under heating. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polylactic acid resin composition, a molded product obtained by molding the polylactic acid resin composition, and a method for producing the same.

  Today, plastic products such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and vinyl chloride are used. These plastic products have extremely high chemical stability, durability, light weight, and excellent strength. Therefore, the plastic products are widely used in various fields.

  However, the plastic product has very high chemical stability and hardly decomposes by microorganisms. Therefore, when the plastic product is disposed in the environment, it may remain semipermanently in the environment. As a result, there is a possibility that problems such as damaging the scenery occur. Conventionally, the plastic products are disposed of by incineration. However, for example, polyethylene and the like have a high combustion calorie, and thus incineration of polyethylene or the like may damage the incinerator. Furthermore, if polyvinyl chloride is incinerated, harmful gases may be generated. Furthermore, conventional plastic products are manufactured from petroleum. Oil is a fossil resource and its reserves are limited. Therefore, the price and supply of plastic products can be influenced by the price and reserves of oil.

  Under these circumstances, development of resins that can be obtained from raw materials other than petroleum and that can be decomposed in a natural environment is underway. As a resin that satisfies this condition, a biodegradable resin derived from a natural product is currently attracting attention. It is known that a biodegradable resin gradually decomposes by hydrolysis or biodegradation in a natural environment, and finally becomes a harmless decomposition product. Specific examples of the biodegradable resin include, for example, biodegradable resins produced by microorganisms (polyhydroxybutyrate, etc.), biodegradable resins obtained by chemical synthesis (polylactic acid, polyglycolic acid, polycaprolactone, polybutylene). And aliphatic polyester resins such as succinate and polyethylene succinate, polyvinyl alcohol and polyamino acid), and biodegradable resins derived from natural products (chitosan, starch, cellulose acetate and the like).

  Among the biodegradable resins, polylactic acid has attracted attention. Polylactic acid can be synthesized using lactic acid synthesized from plants such as corn and sugar millet as a raw material. Polylactic acid has a high melting point and is tough. Therefore, the use of polylactic acid is progressing to applications where petroleum-derived resins are used as plant-derived resins that do not use petroleum resources. Furthermore, polylactic acid is characterized by having transparency as compared with other biodegradable resins. Therefore, polylactic acid is used for films and various sheets taking advantage of transparency.

  However, polylactic acid has problems in that it is inferior in mechanical elongation and flexibility and has low impact resistance compared to other biodegradable resins. In addition, polylactic acid has a problem that heat resistance is lower than that of conventional petroleum-derived resins, such as deformation easily occurring in a high temperature environment of 60 ° C. or higher.

  Therefore, conventionally, a polylactic acid resin composition in which other components are added to polylactic acid in order to improve the physical properties of polylactic acid is known. For example, Patent Document 1 below describes a polylactic acid resin composition containing polylactic acid and fired shell powder. Patent Document 2 below describes a resin composition containing a polylactic acid resin, a polyacetal resin, and an impact resistance improver. Patent Document 2 below describes that this resin composition can further contain a reinforcing agent selected from mica and the like. Further, Patent Document 3 below describes a resin composition containing a polylactic acid resin, a polyacetal resin, and a reinforcing material that is at least one selected from mica, kaolin, and clay.

  Patent Document 4 below describes a synthetic resin composition containing a synthetic resin and a scallop shell pulverized product. And the following patent document 4 describes that the mechanical properties of a molded product such as a flexural modulus can be improved by including a scallop shell pulverized product.

JP 2004-315724 A JP 2003-286400 A JP 2003-286402 A JP 2004-75964 A

  As described above, resins are used in various fields and applications. Among them, there are applications that require higher heat resistance and impact resistance, such as meal-related utensils, OA equipment, and home appliances. In order to be used for such applications, the biodegradable resin needs to be further excellent in heat resistance and impact resistance. Therefore, it is desired to develop a polylactic acid resin composition that is superior in heat resistance and impact resistance as compared with conventional polylactic acid resin compositions.

  An object of this invention is to provide the polylactic acid-type resin composition which was further excellent in heat resistance and impact resistance compared with the conventional polylactic acid-type resin composition. Another object of the present invention is to provide a molded product molded using the polylactic acid resin composition having the above-described excellent properties and a method for producing the molded product.

The present invention is as follows.
(1) When (A) polylactic acid polymer, (B) baked scallop shell pulverized product, and (C) kaolin, and the total amount of the polylactic acid resin composition is 100% by mass, the above (A) poly The content of the lactic acid polymer is 30 to 85% by mass, the content of the (B) baked scallop shell is 5 to 40% by mass, and the content of the (C) kaolin is 5 to 50% by mass. A polylactic acid resin composition characterized by the above.
(2) The poly described in (1) above, wherein the total ratio of (B) baked scallop shell pulverized product and (C) kaolin to 100 parts by mass of (A) polylactic acid polymer is 20 to 250 parts by mass. Lactic acid resin composition.
(3) The polylactic acid resin composition according to the above (1) or (2), wherein the ratio of (C) kaolin to 50 parts by mass of (C) with respect to 100 parts by mass of the pulverized scallop shell (B) is 50 to 200 parts by mass.
(4) A molded article formed by using the polylactic acid resin composition according to any one of (1) to (3) above.
(5) A method for producing a molded product, comprising molding using the polylactic acid resin composition according to any one of (1) to (3).
(6) In the above molding, a dispersion containing (A) a polylactic acid polymer, (B) a baked scallop shell pulverized product, and (C) kaolin in a solvent is prepared, and then the dispersion is used as a mold. The method for producing a molded article according to the above (5), which is performed by pouring, removing the solvent, and then heating.

The polylactic acid-based resin composition and molded product of the present invention are excellent in heat resistance and impact resistance by having the above configuration.
The manufacturing method of the molded article of the present invention can easily obtain a molded article having excellent heat resistance and impact resistance by having the above configuration.
As a method for producing a molded article of the present invention, a dispersion containing (A) a polylactic acid polymer, (B) a baked scallop shell pulverized product, and (C) kaolin in a solvent is prepared. Is cast into a mold, the solvent is removed, and then the molding is performed by heating, whereby a molded product having further excellent heat resistance and impact resistance can be easily obtained.

(1) Polylactic acid-based resin composition The polylactic acid-based resin composition of the present invention contains (A) a polylactic acid-based polymer, (B) a pulverized scallop shell, and (C) kaolin, When the total amount of the resin composition is 100% by mass, the content of the (A) polylactic acid polymer is 30 to 85% by mass, the content of the (B) baked scallop shell is 5 to 40% by mass, Content of said (C) kaolin is 5-50 mass%, It is characterized by the above-mentioned.

(A) Polylactic acid-based polymer The (A) polylactic acid-based polymer is a polymer containing a lactic acid unit or a lactic acid unit and another monomer unit as a monomer unit. That is, as the (A) polylactic acid polymer, both polylactic acid and lactic acid copolymer can be used. As said (A) polylactic acid-type polymer, either one of polylactic acid and a lactic acid copolymer may be used, and both may be used. Furthermore, the (A) polylactic acid-based polymer may use two or more kinds of polylactic acids having different weight average molecular weights. In addition, the (A) polylactic acid-based polymer may use two or more lactic acid copolymers having different weight average molecular weights, types and structures of other monomers, ratios of lactic acid units, and the like.

  A polylactic acid polymer has both crystalline and non-crystalline properties. As said (A) polylactic acid-type polymer, crystalline polylactic acid is suitable. Moreover, as said (A) polylactic acid-type polymer, you may use both a crystalline polylactic acid-type polymer and an amorphous polylactic acid-type polymer.

  The weight average molecular weight of the (A) polylactic acid polymer is not particularly limited. In the present invention, polylactic acid polymers having various weight average molecular weights can be used as necessary. The weight average molecular weight of the (A) polylactic acid polymer is usually 50,000 to 500,000, more preferably 80,000 to 300,000, and more preferably 100,000 to 250,000. This range of weight average molecular weight is applicable to both crystalline polylactic acid polymers and non-crystalline polylactic acid polymers. It is preferable that the weight average molecular weight of the (A) polylactic acid polymer is in the above range since the impact resistance and molding processability of the polylactic acid resin composition can be improved.

  The ratio of the lactic acid unit in the (A) polylactic acid polymer affects the mechanical properties such as biodegradability, transparency, and impact resistance of the polylactic acid resin composition of the present invention. The ratio of the lactic acid unit can be appropriately adjusted according to the properties required for the polylactic acid resin composition. The proportion of the lactic acid unit in the (A) polylactic acid polymer is usually 40 to 100 mol%, preferably 50 to 100 mol%, more preferably 60 to 100 mol%, more preferably 80 to 100 mol. %. When the (A) polylactic acid polymer is a copolymer, the upper limit of the proportion of the lactic acid unit is usually 99 mol%, preferably 95 mol%, more preferably 90 mol%.

  There is no particular limitation on the method for obtaining the (A) polylactic acid polymer. Examples of the method for obtaining the (A) polylactic acid polymer include ring-opening polymerization of lactide (low molecular weight polylactic acid), which is a cyclic diester, and direct dehydration condensation polymerization from lactic acid. In these polymerizations, a polylactic acid polymer containing a lactic acid unit and other monomer units can be obtained by adding the above-mentioned other monomers as necessary.

  The lactic acid can be obtained from plants such as corn, sugar radish, and sugar millet, and old rice. Moreover, the said lactic acid can be obtained from raw garbage etc. by a lactic acid fermentation method. The lactic acid may be either L-lactic acid or D-lactic acid, or both. For example, when the polymerization is carried out by direct dehydration condensation, any lactic acid of L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof may be used. The constituent molar ratio L / D of the L-lactic acid unit and the D-lactic acid unit contained in the lactic acid unit can be in an appropriate range as necessary. The L / D is usually in the range where the (A) polylactic acid polymer has crystallinity. The L / D is preferably 100/0 to 80/20.

  The lactide can be usually synthesized by depolymerizing low molecular weight polylactic acid. As the lactide, any of L-lactide, D-lactide, DL-lactide, meso-lactide or a mixture thereof may be used.

  As long as the other monomer is a monomer copolymerizable with lactic acid or lactide, the type and structure thereof are not particularly limited. Examples of the other monomer include dicarboxylic acids having two or more ester bond-forming functional groups, polyhydric alcohols, hydroxycarboxylic acids, lactones, and derivatives thereof (esters, etc.). . The other monomers may be used alone or in combination of two or more.

  Examples of the dicarboxylic acid include one or more of aliphatic dicarboxylic acids such as succinic acid, adipic acid, and fumaric acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid.

  As said polyhydric alcohol, 1 type, or 2 or more types, such as aliphatic polyhydric alcohol, ether glycol, and aromatic polyhydric alcohol, are mentioned, for example. More specifically, examples of the aliphatic polyhydric alcohol include one or more of ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, glycerin, sorbitan, and the like. . More specific examples of the ether glycol include one or more of diethylene glycol, triethylene glycol, polyethylene glycol, and polypropylene glycol.

  Examples of the hydroxycarboxylic acid include one or more of glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, and 6-hydroxycaproic acid. It is done.

  Examples of the lactone include one or more of glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, and δ-valerolactone. Is mentioned.

  When the total amount of the polylactic acid resin composition of the present invention is 100% by mass, the content of the (A) polylactic acid polymer is usually 30 to 85% by mass, preferably 33 to 80% by mass, and more preferably. Is 35-80 mass%. It is preferable for the content of the (A) polylactic acid polymer to be in the above range because a polylactic acid resin composition having both excellent heat resistance and impact resistance can be obtained.

(B) Pulverized scallop shell (B) The pulverized scallop shell (B) is a material obtained by baking and pulverizing a scallop shell which is a shell belonging to the scallop family. For example, pearl shells and oyster shells are difficult to remove soluble salts even after washing. Therefore, the pulverized product of pearl shells and oyster shells has more residual soluble salts than the scallop shell products. Use of such a shell pulverized product is not preferable because it may cause a decrease in the mechanical strength of the polylactic acid resin composition.

  The average particle size of the pulverized scallop shell (B) may be various as required. In the present invention, the average particle size of the pulverized scallop shell (B) is usually 0.1 to 50 μm, preferably 0.5 to 30 μm, and more preferably 1 to 10 μm. When the average particle size of the (B) baked scallop shell pulverized product is in the above range, the dispersibility of the (B) baked scallop shell pulverized product in the resin composition is increased and uniformly dispersed in the resin composition. Can do. As a result, it is preferable because the mechanical strength of the resulting polylactic acid resin composition can be increased.

  There is no particular limitation on the shape of the baked scallop shell (B). The (B) baked scallop shell pulverized product may be a spherical product or a rod-like particle having an aspect ratio exceeding 1. The shape of the (B) baked scallop shell pulverized product may be, for example, rod-shaped particles having an aspect ratio of 1.5 or more (for example, 1.5 to 10, 2 to 8, 3 to 5).

  When the total amount of the polylactic acid-based resin composition of the present invention is 100% by mass, the content of the pulverized scallop shell (B) is usually 5 to 40% by mass, preferably 7 to 40% by mass, and more preferably. Is 10 to 35% by mass, more preferably 10 to 30% by mass. It is preferable for the content of the (B) baked scallop shell pulverized product to be in the above range since a polylactic acid resin composition having both excellent heat resistance and impact resistance can be obtained.

  There is no limitation in particular in the method of obtaining the said (B) baking scallop shell ground material. Examples of the method for obtaining the (B) baked scallop shell pulverized product include the following methods. That is, (B) the baked scallop shell pulverized product can be obtained by baking the shell of scallop shell as a raw material, cooling and pulverizing. The (B) baked scallop shell pulverized product can be obtained by pulverizing the raw scallop shell and firing the pulverized product. As the raw material, scallop shells themselves may be used instead of scallop shells. When using the scallop shell itself as a raw material, it is preferable to remove components other than the shell as needed.

In the above method, the scallop shell as a raw material can be obtained by separating and removing foreign matters such as marine organisms, seaweed and sand, and then washing and drying a scallop of a required size. Moreover, the raw material scallop can be subjected to a treatment to remove soluble salts (for example, NaCl, KCl, CaCl ₂ , MgCl _2, etc.) as necessary before firing. There is no particular limitation on the method for removing soluble salts from the raw scallop. Examples of the method generally include a method of washing the scallop shell as a raw material (for example, a method of flowing water into a scallop shell as a raw material and a method of immersing a scallop shell as a raw material in water). It is preferable to remove soluble salts from the raw material scallop because the mechanical strength of the polylactic acid resin composition can be increased. Further, as will be described later, when a molded product is obtained by a ceramic technique using the polylactic acid resin composition of the present invention, it is preferable because aggregation of clay in the slurry can be suppressed.

  There are no particular limitations on the firing conditions. The firing conditions can be appropriately set as necessary. The calcination temperature is, for example, 300 to 1000 ° C, preferably 300 to 800 ° C, and more preferably 300 to 600 ° C. The firing time can be, for example, 1 to 24 hours, preferably 2 to 10 hours, and more preferably 2 to 5 hours.

  The pulverization can be performed by a general pulverizer using a pulverizing force such as impact, compression, and friction, such as a hammer mill, a roller mill, a ball mill, and a jet mill. In addition, after the above pulverization, (B) baked scallop shell pulverization having the desired average particle diameter and shape by performing various classification operations such as dry or wet sieving or air classification as required. You can choose things.

(C) Kaolin Kaolin is a natural hydrous aluminum silicate that is mainly composed of kaolinite (Al ₂ O ₃ .SiO ₂ .2H ₂ O) (usually about 90 to 98%. In the present invention, kaolinite The proportion is not limited to this value). Usually, kaolin has a different blending ratio of kaolinite, feldspar, silica and the like depending on the production area. However, the specific type of the (C) kaolin of the present invention is not particularly limited, and various types of kaolin can be used. The (C) kaolin may be used alone or in combination of two or more different kaolins. For example, as the (C) kaolin, two or more kinds of kaolins having different blending ratios such as kaolinite, feldspar, and silica can be used in combination. Specific examples of the (C) kaolin include Australian kaolin, British kaolin, New Zealand kaolin, Spanish kaolin, Hedong kaolin, WA (Korea kaolin) and the like. Furthermore, the above-mentioned (C) kaolin may be calcined kaolin obtained by firing and removing crystal water, or unfired kaolin that has not been fired. Unfired kaolin is suitable for obtaining a molded article by a ceramic technique described later.

  The average particle size of the (C) kaolin is not particularly limited. The average particle diameter of the (C) kaolin is usually 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, and more preferably 1 to 5 μm.

  When the total amount of the polylactic acid-based resin composition of the present invention is 100% by mass, the content of the (C) kaolin is usually 5 to 50% by mass, preferably 5 to 45% by mass, more preferably 7 to 40%. % By mass. It is preferable that the content of the (C) kaolin is in the above range since the heat resistance and impact resistance of the polylactic acid resin composition can be improved.

  The ratio of (C) kaolin to (B) baked scallop shell pulverized product is usually 50 to 200 parts by weight, preferably 75 to 200 parts by weight, more preferably 100 to 200 parts by weight, more preferably. Is 100 to 180 parts by mass. It is preferable that the ratio of the (C) kaolin to the (B) baked scallop shell pulverized product is in the above range since the heat resistance and impact resistance of the polylactic acid resin composition can be improved.

  In the polylactic acid resin composition of the present invention, the total ratio of the (B) baked scallop shell pulverized product and the (C) kaolin relative to 100 parts by mass of the (A) polylactic acid polymer is usually 20 to 250 masses. Parts, preferably 20 to 230 parts by mass, more preferably 25 to 230 parts by mass. It is preferable that the total ratio of the pulverized scallop shell (B) and the kaolin (C) is in the above range because the heat resistance and impact resistance of the polylactic acid resin composition can be improved.

(D) Others The polylactic acid resin composition of the present invention may contain other components as long as the effects thereof are not significantly impaired. Examples of the other components include other resins, other clay minerals, and other additives. Examples of the other resin include other biodegradable resins. Specific examples of the biodegradable resin include, for example, biodegradable resins produced by microorganisms (polyhydroxybutyrate and the like), biodegradable resins obtained by chemical synthesis (polyglycolic acid, polycaprolactone, polybutylene succinate, And aliphatic polyester resins such as polyethylene succinate, polyvinyl alcohol and polyamino acid), and biodegradable resins derived from natural products (chitosan, starch, cellulose acetate, etc.). In addition, said other resin may be used individually by 1 type, and may be used together 2 or more types. In addition, when mix | blending said other resin, you may use a compatibilizing agent together. In addition, the polylactic acid-type resin composition of this invention can be made into the composition which does not contain a polyacetal resin.

  Examples of the other clay minerals include mica, talc, and clay. The above other clay minerals may be used alone or in combination of two or more. In addition, the polylactic acid-type resin composition of this invention can be set as the composition which contains only the said (C) kaolin as a composition which does not contain the said other clay mineral, ie, a clay mineral.

  Other additives include, for example, lubricants (aliphatic metal salts such as calcium stearate and magnesium stearate), crystal nucleating agents, stabilizers, hydrolysis inhibitors, flame retardant aids, coupling agents, antibacterial agents , Antifungal agents, antioxidants, antiblocking agents, UV absorbers, weathering (light resistance) agents, plasticizers, colorants (pigments, dyes, etc.), antistatic agents, foaming agents, silicone oils, and wood flour Can be mentioned. One of these other additives may be used alone, or two or more thereof may be used in combination. Furthermore, as said other additive, fillers, such as glass fiber, carbon fiber, wollastonite, glass bead, glass flake, milled fiber, zinc oxide whisker, and potassium titanate whisker, are used singly or in combination. These can be used together. By blending these fillers, rigidity and the like can be imparted. In addition, the polylactic acid-type resin composition of this invention can be made into the composition which does not contain a coupling agent and a lubricant. For example, it can be obtained by mixing the above components (A) to (C) without including the polylactic acid resin composition, the coupling agent and the lubricant of the present invention. Further, the other additive may be an additive having a plurality of functions. For example, the calcium stearate can function as a crystal nucleating agent in addition to functioning as a lubricant. Therefore, by adding the calcium stearate as the other additive, the same function as when both the lubricant and the crystal nucleating agent are added can be exhibited.

  The polylactic acid-based resin composition of the present invention can be molded in various ways by known molding methods such as sheet / film molding, injection molding, sheet extrusion, vacuum molding, heteromorphic molding, foam molding, injection press, press molding, and blow molding. Product.

As described above, the polylactic acid-based resin composition of the present invention is excellent in heat resistance and impact resistance. More specifically, the polylactic acid-based resin composition of the present invention has a deflection temperature measured under a load of 0.45 MPa according to JIS K7191-2 at 130 ° C. or higher, preferably 150 ° C. or higher. Preferably it can be 160 degreeC or more. The polylactic acid resin composition of the present invention has an Izod impact strength of 3.5 kJ / m ² or more, preferably 4.0 kJ / m ² or more, measured using a notched test piece according to JIS K7110. Preferably it can be 4.5 kJ / m ² or more.

  There is no limitation in particular in the use of the polylactic acid-type resin composition of this invention. As described above, the polylactic acid resin composition of the present invention maintains excellent heat resistance and is excellent in impact resistance as compared with conventional polylactic acid resin compositions. Therefore, the polylactic acid resin composition of the present invention can be used for, for example, packaging materials, agricultural materials, civil engineering and building materials, food-related utensils, and sunday goods such as toys and stationery. In particular, the polylactic acid-based resin composition of the present invention can be widely used in applications requiring heat resistance such as meal-related utensils, OA equipment, and home appliances.

(2) Molded product and its manufacturing method The molded product of the present invention is characterized by being molded using the polylactic acid resin composition of the present invention. Moreover, the manufacturing method of the molded article of this invention is characterized by shape | molding the polylactic acid-type resin composition of this invention.

  The molded article of the present invention can be obtained by immediately molding from the polylactic acid resin composition of the present invention. The molded product of the present invention can be obtained by once pelletizing the polylactic acid resin composition of the present invention and then melt-molding the pellets as necessary. The method of molding after pelletization is preferable because each component contained in the polylactic acid resin composition of the present invention can be more uniformly mixed. In addition, the molded article of this invention may contain the 1 type (s) or 2 or more types of the other additive as needed. Examples of the other additives include the above-mentioned additives. For example, the molded article of the present invention may further contain one or more of fatty acid metal salts such as calcium stearate, fatty acids, fatty acid esters, and fatty acid amides. By including such a component, crystallization is further promoted, and as a result, it contributes to improvement of heat resistance of the molded article of the present invention, which is preferable.

  There is no limitation in particular in the method of obtaining the molded article of this invention. As described above, the molded product of the present invention is a known molding method such as sheet / film molding, injection molding, sheet extrusion, vacuum molding, heteromorphic molding, foam molding, injection press, press molding, and blow molding. It can be obtained by a known molding method. Of these, injection molding is preferred.

  When the molded product of the present invention is obtained by injection molding, a melt-kneaded product of the polylactic acid resin composition of the present invention is usually used. In the above injection molding, the temperature of the melt-kneaded product is usually 170 to 250 ° C, preferably 180 to 200 ° C. When the temperature of the melt-kneaded product is in the above range, the (A) polylactic acid polymer can be melted without being thermally deteriorated, and the (A) polylactic acid polymer and the (B) baked scallop shell pulverized product And (C) Kaolin is preferred because it can be fluidized together.

  When the molded product of the present invention is obtained by injection molding, heat treatment can be further performed after injection molding. By the heat treatment, the (B) baked scallop shell pulverized product and the (C) kaolin can act as a crystal nucleating agent for the (A) polylactic acid polymer. As a result, the heat resistance of the obtained molded product can be improved, which is preferable.

  Examples of the heat treatment method include, for example, a method in which a molded body taken out from a mold is held for a predetermined time in a temperature atmosphere at or above the glass transition temperature of the (A) polylactic acid polymer and less than the melting point, and the glass transition temperature. As mentioned above, the method etc. which heat-process in the metal mold | die set to the temperature below melting | fusing point are mentioned. Specifically, the temperature of the heat treatment may be, for example, 60 to 160 ° C, preferably 80 to 150 ° C, and more preferably 100 to 140 ° C. The heat treatment time is specifically 1 minute to 3 hours, preferably 5 minutes to 2 hours, and more preferably 10 minutes to 1 hour.

  Also in other molding methods, a molded product made of the polylactic acid-based resin composition of the present invention can be obtained by optimizing conditions such as a heat treatment temperature and a heat treatment time.

  The (C) kaolin has a property of having plasticity when mixed with water. Therefore, the molded product of the present invention can be obtained not only by a resin molding method such as injection molding but also by a ceramic method. With the ceramic method, a dispersion or slurry containing each component contained in the polylactic acid resin composition of the present invention in a solvent is prepared into a specific form by a method such as pouring it into a mold, and then, This is a method of forming by heating appropriately. Specific examples of the molding by the ceramic method include potter's wheel molding, cast molding, and the like. More specifically, as the ceramic method, for example, a dispersion containing (A) a polylactic acid-based polymer, (B) a pulverized scallop shell, and (C) kaolin in a solvent is prepared. A method may be mentioned in which the dispersion is poured into a mold, the solvent is removed, and then heated. According to the molding by the ceramic method described above, the gloss of the surface is moderately suppressed as compared with the molded product obtained by the usual resin molding method such as injection molding, and the finish is like a ceramic, and the heat resistance and It is preferable because it is more excellent in impact resistance.

  There is no limitation in particular about the said solvent which comprises the said dispersion liquid and the said slurry. Usually water is used. Further, the amount of the solvent is not particularly limited. When preparing the dispersion, the amount of the solvent is usually 10 to 70 with respect to a total of 100 parts by mass of the (A) polylactic acid-based polymer, (B) pulverized scallop shell, and (C) kaolin. It is a mass part, Preferably it is 15-60 mass parts, More preferably, it is 20-50 mass parts, More preferably, it is 20-40 mass parts.

  When preparing the said dispersion and said slurry, you may add another component as needed. The other components may be used alone or in combination of two or more. For example, in order to improve the dispersibility of each component, especially the (C) kaolin, which is a clay component, a dispersant can be added to the dispersion. There is no limitation in the kind of said dispersing agent, According to the property etc. of said (C) kaolin, it can select suitably. As the dispersant, for example, a dispersant generally used for dispersing clay (soda ash, water glass, NaOH, HCl, polyphosphoric acid, CMC salt, lignin sulfonate, and polyacrylate) is used. be able to. The said dispersing agent may be used individually by 1 type, and may be used together 2 or more types.

  In the molding by the ceramic technique, the heating means and conditions are not particularly limited. Examples of the heating means include heating with an electric furnace and heating with a kiln. Moreover, the temperature of the said heating is 100-300 degreeC normally, Preferably it is 180-250 degreeC. The heating time is usually 30 minutes to 5 hours, preferably 1 to 3 hours.

  Examples of the molded article of the present invention include packaging materials, agricultural materials, civil engineering and building materials, food-related utensils, and sunday goods such as toys and stationery. In particular, the polylactic acid resin composition constituting the molded article of the present invention is excellent in heat resistance and impact resistance. Therefore, the molded product of the present invention can be widely used for applications requiring heat resistance such as meal-related utensils, OA equipment, and home appliances. The above-mentioned meal-related utensils include dishes used for eating directly with food and drinks, dishes used indirectly during meals, and meal-related utensils used indirectly during meals other than the dishes. Means everything. Specific examples of the tableware include tea bowls, dishes, and bowls. Specific examples of the tableware include trays, trays, spoon holders, chopstick trays, teacups, cake molds, butter cases, saucers, and the like. Furthermore, specific examples of the meal-related appliances include spoons, forks, tamales, and muddlers.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not restrict | limited at all by these Examples.

(1) Preparation of polylactic acid-based resin composition and production of molded product As the above-mentioned (A) polylactic acid-based polymer, crystalline polylactic acid pellets (Mw; 123000, D; 0.6%, MFR; 13.5) Was used. Further, as the pulverized scallop shell (B), a pulverized scallop shell having an average particle size of 2 to 3 μm was used. Further, as the above (C) kaolin, unsintered Australian kaolin (trade name “Ekalite Kaolin”, manufactured by Imeris Minerals, average particle diameter of 5 μm) was used.

Using the above raw materials, molded products of the polylactic acid resin compositions of Experimental Examples 1 to 10 were obtained by the following methods A and B.
(Method A)
The crystalline polylactic acid pellets were pulverized by freeze pulverization and classification until the average particle size became 50 μm. Subsequently, the crystalline polylactic acid pellets after pulverization and the other raw materials were mixed. The mixing ratio of each raw material is as shown in Table 1 (unit is part by mass). Thereafter, 30 parts by mass of water is added to 100 parts by mass of each of the above raw materials, and 0.5 to 1% by mass of a dispersant (“Primal N-580-S”, manufactured by Nippon Acrylic Chemical Co., Ltd.) is added. A dispersion was prepared. Next, this dispersion was poured into a plaster mold, and the mold was placed in a drying chamber and dried to remove moisture. Then, the test piece of Experimental example 1, 2, 4-7, 9-10 was manufactured by heating at 200 degreeC for 1.5 hours with an electric furnace.
(Method B)
Each raw material and (D) calcium stearate were mixed in the proportions shown in Table 1 (unit: parts by mass) to prepare a raw material composition. Subsequently, the raw material composition was melt-kneaded using a twin-screw extruder (manufactured by Technobell, φ: 20 mm, L / D; 30) to obtain a pellet. The kneading temperature in the melt kneading is 190 ° C. After drying, injection molding is performed using the pellets by an injection molding machine (manufactured by Meiki Seisakusho Co., Ltd., clamping pressure: 70 t) (mold temperature: 55 ° C., cooling time: 60 seconds), and then 120 ° C. , 30 minutes of heat treatment was performed, and test pieces of Experimental Examples 3 and 8 were manufactured.

(2) Performance evaluation About the molded article of the polylactic acid-type resin composition of the said Experimental Examples 1-10, performance evaluation was performed by the method as described below. The results are shown in Table 1 below.

(A) Izod impact strength (kJ / m ² )
It measured using the test piece with a notch according to JISK7110.
(B) Deflection temperature under load (℃)
According to JIS K7191-2, the measurement was performed under a load of 0.45 MPa.

(3) Results From Table 1, compared with Experimental Example 8 made of polylactic acid, Experimental Examples 1 to 6 which are within the scope of the present invention show large values for both the Izod impact value and the deflection temperature under load. Therefore, it turns out that Experimental Examples 1-6 which are in the range of this invention are excellent in heat resistance and impact resistance.

  Moreover, from Table 1, the deflection temperature under load of Experimental Example 9 that does not contain (C) kaolin shows substantially the same value as Experimental Examples 1 to 6 within the scope of the present invention. However, the Izod impact value of Experimental Example 9 is almost the same as that of Experimental Example 8 made of polylactic acid, which is considerably lower than Experimental Examples 1-6. Furthermore, the experimental example 10 which does not contain the (B) baked scallop shell pulverized product has a considerably lower Izod impact value and deflection temperature under load than the experimental examples 1-6. In addition, in Experimental Example 7 in which the content of the (A) polylactic acid polymer, (B) pulverized scallop shell, and (C) kaolin is outside the scope of the present invention, the Izod impact value of Experimental Example 1 It is considerably lower than 6, and lower than Experimental Example 8 made of polylactic acid. From this result, in order to improve both heat resistance and impact resistance, the (A) polylactic acid polymer, (B) baked scallop shell pulverized product, and (C) kaolin, It turns out that it is necessary to make content into an appropriate range.

  Furthermore, from Table 1, the experimental example 2 obtained by the A method (ceramic technique) compared with the experimental example 3 obtained by the B method (molding method by injection molding of the pellet-like material) Each of the deflection temperatures under load shows a large value. Therefore, according to the molding method by Method A (ceramic technique), a molded product having more excellent heat resistance and impact resistance can be obtained. In addition, when the appearances of the molded products are compared, the experimental example 2 obtained by the A method (ceramic technique) is compared with the experimental example 3 obtained by the B method (molding method by injection molding of pellets). The surface gloss was moderately suppressed, resulting in a ceramic-like finish.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention depending on the purpose and application.

  The polylactic acid resin composition of the present invention is superior in heat resistance and impact resistance as compared with conventional polylactic acid resin compositions. The polylactic acid-based resin composition of the present invention can be used for various applications in which petroleum-derived resins have been used. The polylactic acid resin composition of the present invention can be used, for example, for sundries such as packaging materials, agricultural materials, meal-related utensils, and toys and stationery. In particular, the polylactic acid resin composition and molded product of the present invention and the polylactic acid resin composition obtained by the production method of the present invention are required to have heat resistance such as food-related utensils, OA equipment, and home appliances. And applications that require impact resistance, such as various molded products.

Claims (6)

  When (A) polylactic acid-based polymer, (B) baked scallop shell pulverized product, and (C) kaolin are contained, and the total amount of the polylactic acid-based resin composition is 100% by mass, the above (A) polylactic acid-based heavy The content of the coalescence is 30 to 85% by mass, the content of the pulverized scallop shell (B) is 5 to 40% by mass, and the content of the (C) kaolin is 5 to 50% by mass. A polylactic acid resin composition.   2. The polylactic acid resin composition according to claim 1, wherein the total ratio of (B) baked scallop shell pulverized product and (C) kaolin to 100 parts by mass of (A) polylactic acid polymer is 20 to 250 parts by mass. object.   The polylactic acid-based resin composition according to claim 1 or 2, wherein the ratio of (C) kaolin to 50 parts by mass with respect to 100 parts by mass of the (B) baked scallop shell pulverized product.   A molded article formed by using the polylactic acid resin composition according to any one of claims 1 to 3.   A method for producing a molded product, comprising molding using the polylactic acid resin composition according to any one of claims 1 to 3.   The molding is performed by preparing a dispersion containing (A) a polylactic acid polymer, (B) a baked scallop shell and (C) kaolin in a solvent, and then pouring the dispersion into a mold. The manufacturing method of the molded article of Claim 5 performed by removing a solvent and heating after that.