JP2009024058A - Polylactic acid resin composition and additive for polylactic acid resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid resin composition exhibiting excellent flexibility and heat resistance, without lowering the ratio of plant-originating raw materials. <P>SOLUTION: The polylactic acid resin composition is prepared from polylactic acid and a branched polylactic acid having at least three branched chains composed of polylactic acid in the molecule. The polylactic acid resin composition is very excellent in view of good properties when used for applications such as a sheet due to its flexibility, excellent heat resistance due to its crystallization-accelerating effects, and effectiveness for protection of global environments and for a countermeasure against depletion of fossil resources due to its origin from recyclable resources. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polylactic acid resin composition and an additive for polylactic acid resin, and more specifically, a polylactic acid resin composition excellent in heat resistance and flexibility, and an additive for use in producing the same and an additive for polylactic acid resin About.

  In recent years, there has been a strong demand for the construction of a sustainable society, and material development using renewable raw materials has been actively performed in the polymer material field. Polylactic acid can be synthesized from plant-derived raw materials, and its mechanical strength is similar to that of existing plastics. Therefore, it is attracting attention as an alternative to petroleum-derived plastics. However, since it is poor in heat resistance and flexibility, it is a big problem in developing a wide range of applications.

  As an example of improving the flexibility of polylactic acid, an example of polylactic acid containing 10 to 40% lactic acid or lactide, or 10 to 60% linear lactic acid oligomer or lactide oligomer is disclosed (Patent Document 1). . However, the low molecular weight compound contained in the resin tends to cause so-called bleeding that oozes out on the surface. This is because the low molecular weight compound is compatible with the non-crystalline part of polylactic acid, and the molecular chain in this part is easily moved by the additive, but by adding external energy, the non-crystalline part gradually crystallizes. This is because the compatible portion is reduced and the low molecular weight compound is pushed out to the surface. On the other hand, when a relatively high molecular weight linear lactic acid oligomer is blended, unlike the low molecular weight compound, bleeding hardly occurs, but the added lactic acid oligomer itself has crystallinity and hinders the plasticizing effect.

  Moreover, the example of the polylactic acid composition which added the derivative | guide_body of lactic acid as an example which improves the softness | flexibility of polylactic acid is disclosed (patent document 2). However, in this case as well, the additive is a low molecular weight compound, and depending on the amount added, so-called bleeding in which the additive oozes out to the surface tends to occur. The problem is that the additive is extruded onto the surface.

  Moreover, the example of the composition of a cyclic | annular lactic acid oligomer and polylactic acid is disclosed as an example which improves the softness | flexibility of polylactic acid (patent document 3). Since a combination of lactic acid-derived oligomer and polymer can provide flexibility, transparency and plantiness (ratio of plant-derived raw materials) can be maintained. However, the effects of plasticization are not sufficient, the yield of cyclic lactic acid oligomer production is low, and the molecular weight of the cyclic oligomer is difficult to control.

  In addition, in order to give flexibility to polylactic acid, modification with blends of other resins and fillers has been studied, but it impairs the transparency of polylactic acid and reduces the plant degree (ratio of plant-derived raw materials) It has become a problem.

  On the other hand, in order to raise the heat resistance of polylactic acid, the method of adding inorganic fillers, such as talc and mica, which has heat resistance, is mentioned, for example. That is, by adding an inorganic filler having high heat resistance to the resin, the effect of improving and hardening the mechanical properties can be obtained. However, it is difficult to ensure sufficient heat resistance in practical use only by adding an inorganic filler to the resin, resulting in a new problem that the specific gravity is increased.

  Conventionally, a technique for improving the heat resistance of polylactic acid has been proposed by performing heat treatment during or after molding. Polylactic acid is a material that can have a crystal structure, but it is a polymer that is difficult to crystallize. Therefore, if polylactic acid is molded in the same way as ordinary general-purpose resins, the molded product becomes amorphous. It is inferior in mechanical strength and is likely to cause thermal deformation.

  In contrast, by performing heat treatment during or after molding, polylactic acid can be crystallized, and the heat resistance of the molded product can be improved. However, such a crystallization method by heat treatment has a practical problem that a long time is required for crystallization. It takes a considerable amount of time to finish the crystallization of the molded product of polylactic acid through a heat treatment step in the mold. In addition, when crystallizing with polylactic acid alone without adding a substance that becomes a crystal nucleus of polylactic acid, the crystal nuclei are generated on the order of microns because the frequency of free generation of crystal nuclei is small. The crystal itself becomes a factor of light scattering and becomes cloudy, the transparency is lost, and the practical effectiveness is reduced. With respect to polymers that can take a crystal structure, a technique of adding a nucleating agent has been studied in order to solve the above-described problems, that is, to promote crystallization of a polymer that can take a crystal structure. The nucleating agent is a primary crystal nucleus of the crystalline polymer and promotes crystal growth of the crystalline polymer. Also, in a broad sense, a nucleating agent is a substance that promotes crystallization of a crystalline polymer, that is, increases the crystallization rate of the polymer itself. When the nucleating agent is added to the resin, the polymer crystals can be refined, and the rigidity can be improved or the transparency can be improved. Further, when crystallization is performed during molding, there is also an advantage that the molding cycle can be shortened because the overall speed (time) of crystallization is increased.

  Examples of conventional methods for promoting crystallization of polylactic acid include talc, layered viscosity compounds, dimethyl metal sulfoisophthalate, addition of copper phthalocyanine, and alloys with polycarbonate. There is a problem in that the plant degree (ratio of plant-derived raw materials) is reduced rather than the additive as the origin.

  In addition, as an additive that does not reduce the degree of plant, a component A made of poly-D lactic acid or a copolymer resin of D-lactic acid and starch, and a biodegradable resin whose melting point or softening point is lower than the melting point or softening point of polylactic acid The example which mixes the block polymer with B component which consists of in polylactic acid is disclosed (patent document 5). However, this additive has low compatibility with polylactic acid, and there is a problem that stability in the composition is lowered. Since it is necessary to add a compatibilizing agent, it becomes a problem to reduce plantiness after all.

Moreover, the example which mixes amino acids, such as tryptophan and phenylalanine, in polylactic acid is disclosed (patent document 6). However, these additives have low compatibility with polylactic acid, and it is necessary to control the particle size distribution and the amount added, and in order to prevent aggregation, it is also necessary to add an aggregation inhibitor. The problem is to reduce the degree.
US Pat. No. 5,180,765 Japanese Patent Laid-Open No. 9-100401 JP-A-6-306264 JP 2005-146274 A JP 2007-063516 A JP 2007-282940 A

  This invention makes it a subject to provide the polylactic acid resin composition excellent in a softness | flexibility and heat resistance, without reducing a plant degree. Another object of the present invention is to provide an additive for a polylactic acid resin that can be added to a polylactic acid resin to improve its flexibility and heat resistance.

  As a result of intensive studies to solve the above problems, the present inventors have added polylactic acid having a different molecular structure to polylactic acid, so that polylactic acid is plasticized and / or promoted for crystallization. I found out. By promoting crystallization, heat resistance is improved. That is, it has been found that flexibility and heat resistance can be improved by combining polylactic acids having different molecular structures.

  Branched polylactic acid, which is a polylactic acid having a different molecular structure, is a multi-branched polylactic acid having oil and fat as a basic skeleton. By being multi-branched, the crystallization of the molecular chain is hindered, the crystallinity is low, the melting point is low, and more flexible. Therefore, even if a relatively high molecular weight branched polylactic acid is added to suppress bleed or the like, which has been a conventional problem, it is amorphous per se and does not hinder plasticization.

  Furthermore, since such multibranched polylactic acid and the polylactic acid blended therewith are all made of plant-derived raw materials, the plant degree is not lowered even in a polylactic acid resin composition in which these are combined. In addition, this blend is compatible at the molecular level, is a stable composition, has a small crystal size, and has a similar structure so that the refractive index is close and transparency can be maintained. is there.

  The present invention has been conceived based on these findings, and includes polylactic acid and branched polylactic acid having at least three branched chains composed of polylactic acid in the molecule. It is a composition.

  In addition, what is simply referred to as “polylactic acid” in the present specification has a general and substantially branched structure mainly composed of L-lactic acid and / or D-lactic acid, as will be described later. In the present specification, it is used in a sense not including at least “branched polylactic acid having at least three branched chains composed of polylactic acid in the molecule”.

  In one embodiment of the present invention, the branched polylactic acid is a polylactic acid resin composition in which the branched polylactic acid is polylactic acid polymerized by using an oil whose main component is triacylglycerol having at least three hydroxyl groups in the molecule as an initiator. Is shown.

  In a further embodiment of the present invention, there is shown a polylactic acid resin composition in which the fat is castor oil, polycastor oil, hydrogenated castor oil, or hydroxylated soybean oil.

  In another embodiment of the present invention, the branched polylactic acid is a polylactic acid resin that is a polylactic acid polymerized by using an oil whose main component is triacylglycerol having at least three epoxy groups in the molecule as an initiator. A composition is shown.

  In a further embodiment of the present invention, a polylactic acid resin composition is shown in which the fat is epoxidized soybean oil, epoxidized palm oil, or epoxidized linseed oil.

  In one embodiment of the present invention, a polylactic acid resin composition in which the weight molecular weight of the branched polylactic acid is 1000 or more and 30000 or less is shown.

  In still another embodiment of the present invention, a poly (lactic acid) comprising 1 to 30 parts by weight of a branched polylactic acid having at least three branched chains composed of polylactic acid in the molecule is added to the polylactic acid. A lactic acid resin composition is shown.

  In another embodiment of the present invention, there is shown a polylactic acid resin composition which is a branched polylactic acid in which the hydrogen at the terminal hydroxyl group of the branched polylactic acid is substituted with an acyl group.

  In still another embodiment of the present invention, there is shown a polylactic acid resin composition which is a branched polylactic acid in which the terminal hydroxyl group of the branched polylactic acid is ester-bonded to a dicarboxylate.

  In still another embodiment of the present invention, the terminal hydroxyl group of the branched polylactic acid is ester-bonded with a dicarboxylate, and the carboxyl group that does not affect the ester bond forms a salt with a cation. A polylactic acid resin composition that is branched polylactic acid is shown.

  The present invention that solves the above problems is also achieved by a resin composition obtained by melt-mixing a polylactic acid with an oil or fat mainly composed of triacylglycerol having at least three epoxy groups in the molecule.

  That is, even in the case where such fats and oils mainly composed of triacylglycerol are melt-mixed in polylactic acid, in the resin composition during the melt-mixing or subsequent resin processing step, Since the terminal epoxy group of triacylglycerol is ring-opened and reacts with the carboxy terminus of polylactic acid to form an ester bond, a branched polylactic acid structure is formed in the resin composition. The same action as that of the polylactic acid resin composition obtained by blending the polylactic acid is produced.

  The present invention also shows an additive for polylactic acid resin, which is a branched polylactic acid having at least three branched chains composed of polylactic acid in the molecule.

  ADVANTAGE OF THE INVENTION According to this invention, the polylactic acid resin composition which improved the softness | flexibility by plasticization or heat resistance by acceleration | stimulation of crystallization can be provided.

  Hereinafter, the present invention will be described in more detail based on embodiments.

(Branched polylactic acid)
The branched polylactic acid according to the present invention has a low melting point and is designed to be composed of renewable resources. That is, the branched polylactic acid according to the present invention is a branched polymer having at least three branched chains (that is, a polylactic acid chain or a lactic acid oligomer chain) containing lactic acid as a structural unit (FIGS. 1 and 2). checking).

  Note that the number of branched chains having lactic acid as a structural unit is not necessarily limited to three, and may be more than this, specifically about 3 to 12, for example, more preferably 3 ˜8 or so. Further, the skeleton structure of the branched polymer may take various forms such as a comb shape, a resin shape, and an explosive star shape in addition to the star shape as shown in FIG.

  Specifically, branched polylactic acid in which the carboxy terminus of polylactic acid is ester-bonded to the hydroxyl group of an oil (triacylglycerol) having at least three hydroxyl groups in the molecule (FIG. 1).

  Alternatively, branched polylactic acid in which the epoxy group of an oil (triacylglycerol) having at least three epoxy groups in the molecule is ring-opened and the carboxy terminals of polylactic acid are respectively ester-linked (FIG. 2). ).

  For this reason, at least three polylactic acid chains extend starting from oil and fat, and a hydroxyl group exists at the end of each polylactic acid chain. Such a branched polylactic acid has a lower melting point and lower crystallinity than a linear polylactic acid even if it has the same molecular weight. Moreover, depending on the composition of the oil and fat and the polylactic acid chain, it may be non-crystalline.

  In the branched polylactic acid according to the present invention, as a lactic acid component constituting a branched chain having lactic acid as a structural unit (that is, polylactic acid chain or lactic acid oligomer chain), L-lactic acid, D-lactic acid, racemic body, etc. Any of DL mixture may be sufficient.

  In addition, as shown also in the Example mentioned later, the direction which contains D body (D body or DL body) as a lactic acid component of branched polylactic acid has a higher plasticizing effect with respect to general polylactic acid. Can be expected. However, even when the lactic acid component of the branched polylactic acid is only in the L form, a sufficient modification effect is brought about. From an economical viewpoint, the L-shaped branched polylactic acid is also sufficiently preferable. Is.

  Further, the molecular weight of the molecular polylactic acid according to the present invention is not particularly limited as long as it provides the intended mechanical properties, flexibility, etc. according to the intended use of the polylactic acid resin composition obtained. The weight average molecular weight is, for example, about 1000 to 30000, more preferably about 5000 to 15000, although it depends on the molecular weight and optical characteristics of the polylactic acid used in combination. be able to.

  Such a branched polylactic acid is prepared by, for example, (a) ring-opening polymerization of lactide using an oil whose main component is triacylglycerol having at least three hydroxyl groups in the molecule, or (b ) It can be obtained by any step of dehydration condensation polymerization of lactic acid. Alternatively, (c) a step of ring-opening polymerization of lactide or (d) a step of dehydration condensation polymerization of lactic acid using an oil and fat mainly composed of triacylglycerol having at least three epoxy groups in the molecule as an initiator. It can be obtained by any of the following processes.

  In the branched polylactic acid according to the present invention, it is preferable that the hydrogen in the terminal hydroxyl group is substituted with an acyl group. By condensing a terminal hydroxyl group of a branched polylactic acid and a carboxylic acid, a branched polylactic acid having an acylated terminal can be obtained.

  As the acyl group (R—CO—), R in the above general formula such as formyl group, acetyl group, propionyl group, butyryl group, benzoyl group is H or a saturated or unsaturated hydrocarbon residue having about 1 to 10 carbon atoms. Examples of the acyl group include, but are not limited to, an acyl group.

  Moreover, in other embodiment, it is preferable that the terminal hydroxyl group of the branched polylactic acid which concerns on this invention is ester-bonded with dicarboxylic acid. By condensing the terminal hydroxyl group of the branched polylactic acid and the dicarboxylic acid, a branched polylactic acid in which the terminal hydroxyl group of the branched polylactic acid is ester-bonded to the dicarboxylic acid can be obtained. As the dicarboxylic acid (HOOC-R-COOH), for example, R in the above general formula such as oxalic acid, malonic acid, succinic acid, phthalic acid, glutaric acid, adipic acid, etc. is H or saturated with about 1 to 10 carbon atoms. Alternatively, dicarboxylic acid which is an unsaturated hydrocarbon residue may be mentioned, but it is not limited thereto.

  In another embodiment, it is more preferable that the terminal hydroxyl group of the branched polylactic acid according to the present invention is ester-bonded to a dicarboxylate. After condensing the terminal hydroxyl group of the branched polylactic acid and the dicarboxylic acid, the terminal hydroxyl group of the branched polylactic acid is ester-bonded to the dicarboxylic acid salt by neutralizing with alkali such as metal hydroxide or metal alcoholate. Branched polylactic acid. As the dicarboxylic acid (HOOC-R-COOH), for example, R in the above general formula such as oxalic acid, malonic acid, succinic acid, phthalic acid, glutaric acid, adipic acid, etc. is H or saturated with about 1 to 10 carbon atoms. Alternatively, dicarboxylic acid which is an unsaturated hydrocarbon residue may be mentioned, but it is not limited thereto.

(Initiator)
The oil used as the initiator is mainly composed of triacylglycerol having at least 3 hydroxyl groups in the molecule or triacylglycerol having at least 3 epoxy groups in the molecule. Hereinafter, these fats and oils may be referred to as hydroxylated fats and oils or epoxidized fats and oils, respectively.

  In the present invention, fats and oils refer to esters of fatty acids (higher fatty acids) having a large number of carbon atoms, specifically 8 or more carbon atoms, more preferably about 14 to 20 carbon atoms, and glycerin. Fat oil that is liquid at room temperature, such as bean oil, and solid fat, such as lard and beef tallow, are collectively referred to as fat. In the present invention, natural oil-derived fats and oils are preferable because they are renewable resources. Such fats and oils are obtained by means usually used by those skilled in the art. For example, beans and seeds are used as raw materials, and after pre-treatment such as threshing, pulverization, and steaming (heat treatment), oil is extracted by methods such as fusion, pressing, extraction, degumming, deoxidation, and decolorization. It is obtained by a purification process such as deodorization.

  Oils and fats have various characteristics depending on the types of fatty acids constituting them. In the present invention, fats and oils mainly composed of triacylglycerol having many hydroxyl groups as starting points are suitable as initiators. Examples of such fats and oils include, but are not limited to, corn oil, sesame oil, peanut oil, kapok oil, castor oil, and the like.

  Castor oil (Castor oil in English, Castor oil in English) is a vegetable oil collected from the seeds of Euphorbiaceae, which is ricinoleic acid having a hydroxyl group in which about 90% of the constituent fatty acids are a kind of unsaturated fatty acid. Castor oil is suitable as an initiator because the hydroxyl value of many fats and oils is 10 mgKOH / g, whereas the hydroxyl value is as large as 155 to 177 mgKOH / g.

  Polycastor oil is a polymer of castor oil. An unsaturated bond (C = C) derived from ricinoleic acid in a castor oil molecule undergoes radical polymerization using an organic peroxide or the like as an initiator to become polycastor oil. Polycastor oil has a more branched structure than castor oil, and the number of hydroxyl groups in the oil / fat molecule is larger than castor oil. Therefore, polycastor oil has more hydroxyl groups that serve as starting points for polymerization and has a more branched structure, and is therefore more suitable as an initiator in the production of the polyester polyol of the present invention.

  Or the hydroxylated fats and oils which introduce | transduced the hydroxyl group into the carbon-carbon unsaturated bond in unsaturated fatty acids, such as linoleic acid and oleic acid, can also be used as an initiator of the polyester polyol of this invention. Examples of hydroxylated fats and oils include hydroxylated soybean oil, hydroxylated linseed oil, hydroxylated rapeseed oil, hydroxylated palm oil, hydroxylated corn oil and the like.

  In the present invention, fats and oils mainly composed of triacylglycerol having a large number of starting epoxy groups as an initiator are also suitable. Epoxidized fats and oils in which an epoxy group is introduced into a carbon-carbon unsaturated bond derived from an unsaturated fatty acid such as linoleic acid or oleic acid can be used as an initiator for the polyester polyol of the present invention. Epoxidized oils and fats include epoxidized soybean oil, epoxidized linseed oil, epoxidized palm oil and the like. These epoxidized oils and fats are industrially used as additives in resins such as vinyl chloride resins for applications such as imparting plasticity.

  In addition, in the fats and oils having the above hydroxyl group or epoxy group, it is possible to use a hardened oil which is hydrogenated to the unsaturated group of the constituent fatty acid to obtain a saturated fatty acid. By using a hardened oil, the stability of the resulting branched polylactic acid to heat can be increased, the solubility can be modified, and compatibility with rosin, waxes, rubbers, polyethylene, and the like can be achieved. Moreover, solvent resistance, grease resistance, and hardness of the obtained branched polylactic acid can be improved by blending with other waxes.

  In addition, the fats and oils used as an initiator may be a mixture of fats and oils having different fatty acids, and may contain fats and oils having less than 3 hydroxyl groups or epoxy groups in the molecule as impurities. In many cases, fats and oils are not pure substances but mixtures, so that the main component may be fats and oils having at least three hydroxyl groups or epoxy groups in the molecule. The ratio of the fats and oils having at least three hydroxyl groups or epoxy groups in the fats and oils used as the initiator is preferably 50% by mass or more, and more preferably 70% by mass or more. If it is less than 50% by mass, a large amount of linear polyester polyol is formed, and the glass transition temperature, the melting point and the crystallinity become high.

(Lactide and lactic acid)
The branched polylactic acid according to the present invention can be synthesized by polymerizing lactide or lactic acid in the presence of the above-described initiator.

  Lactic acid can be obtained by fermenting an assimitable carbon source such as glucose using a microorganism such as lactic acid bacteria. Glucose, which is a carbon source, can be obtained from the petroleum industry, but can be produced by hydrolysis of many renewable resources such as cellulose and starch. Therefore, lactic acid is also a renewable resource. In the present invention, the lactic acid fermentation broth may be used as it is, lactic acid isolated from the lactic acid fermentation broth may be used, or commercially available lactic acid may be used.

  In the present invention, lactide refers to a cyclic diester obtained by dehydration condensation of two molecules of lactic acid. Therefore, it is a renewable resource. In the present invention, commercially available lactide can be used.

  Optical isomers exist in lactic acid and lactide. In many cases, only L-form is obtained by fermentation of lactic acid bacteria. However, some microorganisms (eg, Lactobacillus lactis, Lactobacillus bulgaricus, Leuconostoc cremoris) produce D-form. DL type (racemic) lactic acid can be obtained by mixing several types of microorganisms including such microorganisms and subjecting them to fermentation. In addition, L-lactic acid can be racemized by a microorganism that produces lactate racemase to produce DL-form lactic acid.

(Production of branched polylactic acid by ring-opening polymerization of lactide)
Since lactide has a structure in which two molecules of lactic acid are cyclized, a polylactic acid chain can be synthesized by ring-opening polymerization of lactide. For example, lactide and initiator (hydroxylated oil or epoxidized oil) are placed in a sufficiently dry container, purged with an inert gas, charged with catalyst, heated and stirred, and lactide starting from the initiator. A polyester polyol having a polylactic acid chain obtained by ring-opening polymerization can be produced.

  When using an epoxidized oil as an initiator, the lactide may be subjected to an addition reaction with lactide to synthesize modified oil with lactide, and then the lactide may be subjected to ring-opening polymerization or obtained by polymerizing lactide alone. The obtained polylactic acid may be subjected to an addition reaction with fats and oils.

Examples of the catalyst for polymerizing lactide include those usually used by those skilled in the art. Specifically, porphyrin aluminum _{complexes, (n-C 4 H 9} O) 4 Al 2 O 2 Zn, double metal cyanide complexes, tin dichloride (SnCl _2), tin 2-ethylhexanoate, diethylzinc - Water Or diethyl cadmium, aluminum triisopropoxide, titanium tetrabutoxide, zirconium tetrapropoxide, tributyltin methoxide, tetraphenyltin, lead oxide, zinc stearate, bismuth 2-ethylhexanoate, potassium alcoholate, antimony fluoride catalyst, industrial Specific examples include, but are not limited to, stannous octanoate catalysts. From the viewpoint of yield, tin dichloride (SnCl ₂ ) and tin 2-ethylhexanoate are particularly preferable.

  Although the usage-amount of a catalyst is not specifically limited, About 0.0001-5 mass parts is suitable with respect to 100 mass parts lactide, About 0.05-1 mass part is preferable.

  Although it does not specifically limit as an inert gas, For example, nitrogen gas and argon gas are mentioned.

  The polymerization reaction can be performed at room temperature, but is heated as necessary. Preferably it heats in the range of 100 to 180 degreeC, More preferably, it heats to 120 to 160 degreeC. Less than 100 ° C. is not preferable because the reaction rate becomes small. On the other hand, at a temperature higher than 180 ° C., there are disadvantages such as an increase in decomposition rate and vaporization of low molecular weight substances.

(Production of branched polylactic acid by dehydration condensation polymerization of lactic acid)
Lactic acid is a compound having a carboxyl group and a hydroxyl group in one molecule, and a polylactic acid chain can be synthesized by polymerizing lactic acid by condensation. For example, lactic acid and initiator (hydroxylated oil or epoxidized oil) are placed in a fully dried container, and if necessary, a catalyst is added and heated or heated under reduced pressure to condense lactic acid starting from the initiator. A branched polylactic acid having a polymerized polylactic acid chain can be produced. The degree of polymerization can be further increased by discharging water produced by the polymerization out of the reaction system.

  When using an epoxidized oil as an initiator, lactic acid may be added to the oil and fat to synthesize the modified oil and fat with lactic acid, and then dehydrated by condensation polymerization of lactic acid, or obtained by polymerizing lactic acid alone. The obtained polylactic acid may be subjected to an addition reaction with fats and oils.

  In the case of solution polymerization using a solvent, the temperature of the polymerization reaction may be a temperature from the azeotropic point of the solvent and dehydrated water to the boiling point of each solvent. However, since the modification of the oil and fat component is likely to occur as the temperature becomes higher, the heating is preferably 200 ° C. or lower. For example, castor oil decomposes above 200 ° C. In order to cause dehydration, the heating is preferably performed for a time (for example, 1 to 24 hours) suitable for obtaining an appropriate degree of polymerization at an azeotropic point or higher (for example, 90 ° C. to 180 ° C. is preferable). preferable.

  In the case of heat-reduced-pressure polymerization, in the process of lactic acid polymerization, it may be produced by a depolymerization reaction of a lactic acid oligomer to generate lactide. Lactide becomes an impurity in the case of lactic acid polymerization. The higher the temperature or the higher the vacuum, the easier the lactide is generated, and the generated lactide disappears from the system by sublimation, thereby reducing the yield of polylactic acid chains. Therefore, the heating temperature is preferably 100 ° C. to 180 ° C., and the reduced pressure is preferably 670 Pa to 13000 Pa. When it is higher than 13000 Pa, the moisture content in the reaction system becomes high and the condensation does not easily proceed. If it is less than 670 Pa, the production | generation and sublimation of a lactide will occur easily, and the yield of the product to collect will fall.

Examples of the catalyst for polymerizing lactic acid include those usually used by those skilled in the art. Specific examples include tin dichloride (SnCl ₂ ), tin 2-ethylhexanoate, tetraphenyltin, tin oxide, sulfuric acid, tin powder, and toluenesulfonic acid, but are not limited thereto.

  Although the polymerization reaction rate is low, it is possible to perform polymerization without adding a catalyst. In particular, when a polyester polyol having a relatively low molecular weight is produced, a catalyst is not essential because the charging ratio of lactic acid to the initiator is small.

  As a method for discharging water from the reaction system, a method usually performed by those skilled in the art is adopted, and for example, dehydration is performed from the reaction system by azeotropy with a solvent. Solvents that can be azeotroped with water include, but are not limited to, toluene, xylene, mesitylene, ethylbenzene, and mineral spirits. By heating to above the azeotropic point with water in these solvents, water can be distilled out of the reaction system and the dehydration condensation of lactic acid can be promoted.

  In addition, since the specific gravity of toluene, xylene, mesitylene, ethylbenzene, and mineral spirit is less than 1, the specific gravity can be separated from water. When heated at a temperature equal to or higher than the azeotropic point with water, an azeotrope of water and a solvent is distilled off, and when this distillate is cooled, a condensate is obtained. Since the solvent and water have a specific gravity difference, this condensate is separated into water and solvent. Therefore, the separated water can be removed. Furthermore, the solvent can also be recovered and recycled to the reaction system for reuse.

  Specifically, the azeotrope of water and solvent is distilled from the heating reaction tank by heating. This distillate is condensed in a cooling pipe, led to a water separator, and separated into lower layer water and upper layer solvent by specific gravity difference. For this purpose, it is preferable to provide a heating reaction tank equipped with a steam outlet with a cooling pipe and a water separator such as a decanter or a Dean-Stark trap. In the water separator, the lower layer water can be removed from the system, and the upper layer solvent can be refluxed and circulated in the heated reaction tank. Therefore, it can be dehydrated from the condensation reaction system of lactic acid without consumption or leakage of the solvent.

(Acylation of branched polylactic acid)
In one embodiment of the present invention, it is preferred that the hydrogen in the terminal hydroxyl group of the branched polylactic acid is substituted with an acyl group. The terminal hydroxyl group of the branched polylactic acid can be condensed with a carboxylic acid to give a branched polylactic acid whose terminal is acylated. The branched polylactic acid can be acylated by acting a carboxylic acid chloride or a carboxylic acid anhydride. For example, when substituting with one kind of acyl group acetyl group, the terminal hydroxy group may be acetylated by allowing acetyl chloride or acetic anhydride to act on branched polylactic acid in the presence of a base such as pyridine or triethylamine. it can.

  Moreover, in other embodiment, it is preferable that the terminal hydroxyl group of the branched polylactic acid which concerns on this invention is ester-bonded with dicarboxylic acid. The terminal end of the branched polylactic acid is a hydroxyl group, but by using a dicarboxylic acid chloride or dicarboxylic anhydride, a branched polylactic acid in which the terminal hydroxyl group is ester-bonded to the dicarboxylic acid can be obtained. it can. For example, by reacting branched polylactic acid with phthalic anhydride in the presence of a base such as pyridine or triethylamine, the terminal hydroxyl group of branched polylactic acid can be converted to an ester with dicarboxylic acid.

  Moreover, in other embodiment, it is preferable that the terminal hydroxyl group of the branched polylactic acid based on this invention is ester-bonded with the dicarboxylate. The terminal of branched polylactic acid is a hydroxyl group, but the terminal hydroxyl group is ester-bonded to the dicarboxylate by reacting with dicarboxylic acid chloride or dicarboxylic acid anhydride and neutralizing with a base. It can be branched polylactic acid. For example, by reacting branched polylactic acid with phthalic acetic anhydride in the presence of a base such as pyridine or triethylamine, and further neutralizing with sodium hydroxide, the terminal hydroxyl group of branched polylactic acid is dicarboxylate. And can be an ester. After neutralization, since the ester with the dicarboxylate is insoluble, the branched polylactic acid in which the terminal hydroxyl group is ester-bonded to the dicarboxylate is obtained by recovery by centrifugation or filtration and washing. be able to.

(Production of branched polylactic acid from lactic acid fermentation broth)
Lactic acid as a raw material of the present invention may be produced by chemical synthesis, but most are produced by lactic acid fermentation by lactic acid bacteria. Therefore, lactic acid is obtained as a lactic acid fermentation broth.

  The lactic acid fermentation broth refers to an aqueous liquid in which lactic acid is produced by lactic acid fermentation of an assimitable carbon source such as glucose using a microorganism such as lactic acid bacteria. In the lactic acid fermentation broth, bacteria such as lactic acid bacteria, lactic acid produced by fermentation, carbon sources such as glucose that have not yet been assimilated, by-products (acetic acid, formic acid, etc.), medium components that are nutrient sources of bacteria, etc. included. Medium components differ depending on the type of bacteria, but organic components such as amino acids, peptides, vitamins, nucleotides, and surfactants, and phosphate, sulfate, acetate, and citrate Such inorganic components are included. For example, MRS (de Man-Rogosa-Sharpe) medium, which is a typical medium for lactobacilli, includes peptone, meat extract, yeast extract, potassium phosphate, diammonium citrate, sodium acetate, magnesium sulfate, manganese sulfate. , And surfactants. In addition, typical medium M17 medium for lactic acid cocci includes tryptone, soybean peptone, labrolecom powder, yeast extract, ascorbic acid, magnesium sulfate, and disodium glycerophosphate. Therefore, the lactic acid fermentation broth is a mixed solution containing many solutes including lactic acid, and is usually colored from yellow to brown. The concentration of lactic acid in the lactic acid fermentation broth can usually be about 10 to 150 g / L.

  In the production of the branched polylactic acid according to the present invention, the lactic acid fermentation broth may be used as it is, or the cells in the lactic acid fermentation broth may be removed in advance. Since the bacterial cells are insoluble in water, the bacterial cells can be removed by collecting the lactic acid fermentation broth and then collecting the supernatant. Moreover, you may remove a microbial cell by centrifugation or filtration.

  In the production of branched polylactic acid according to the present invention, after adding dehydration polycondensation by adding a hydroxylated fat or epoxidized fat as an initiator to a lactic acid fermentation broth, branching according to the present invention is recovered. -Like polylactic acid can be obtained. The branched polylactic acid according to the present invention is water-insoluble and has a specific gravity of less than 1, whereas the other components contained in the fermentation broth are water-soluble. Thus, the obtained branched polylactic acid can be easily recovered.

  Furthermore, when other components contained in the lactic acid fermentation liquor are solid at room temperature, these components are deposited on the bottom and wall surfaces of the reaction vessel during the dehydration polycondensation step and dry to solidification. Water can be added to dissolve the dried product in water and separated from the upper oil. At this time, even if there are water-insoluble components such as lactic acid bacteria, the specific gravity is greater than 1 and settles in the reaction vessel, so that it is not necessary to separate them in advance.

(Polylactic acid)
In the polylactic acid resin composition of the present invention, the polylactic acid used together with the above-described branched polylactic acid is a polymer mainly composed of L-lactic acid and / or D-lactic acid.

  In the present invention, in order to obtain a resin composition having particularly high heat resistance, it is preferable to use a polylactic acid resin having a high optical purity of the lactic acid component. Of the total lactic acid component of the polylactic acid resin, it is preferable that the L-form is contained at 80% or more, or the D-form is contained at 80% or more, the L-form is contained at 90% or more, or the D-form is contained at 90% or more It is particularly preferable that the L-form is contained at 95% or more or the D-form is contained at 95% or more.

  Moreover, the polylactic acid used for the polylactic acid composition of this invention may contain the other monomer unit which does not originate in L-lactic acid or D-lactic acid. For example, other hydroxycarboxylic acids can be included. Other hydroxycarboxylic acids include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2- Examples thereof include bifunctional aliphatic hydroxy-carboxylic acids such as methyl lactic acid and 2-hydroxycaproic acid, and lactones such as caprolactone, butyrolactone and valerolactone.

  Other monomer units include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentylglycol, glycerin, Glycol compounds such as pentaerythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalate Acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4'-diphenyl ether Examples of the dicarboxylic acid include dicarboxylic acid, 5-sodium sulfoisophthalic acid, and 5-tetrabutylphosphonium isophthalic acid, but are not limited thereto as long as they can be incorporated into the polyester skeleton that is polylactic acid by a polycondensation reaction. Is not to be done.

  The content of the other monomer is preferably 0 to 30 mol%, and preferably 0 to 10 mol%, based on all monomer components.

  The polylactic acid used in the polylactic acid composition of the present invention can be produced by a known method. As a polymerization method of polylactic acid, a condensation polymerization method, a ring-opening polymerization method, and other known polymerization methods can be employed. For example, in the condensation polymerization method, polylactic acid having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of L-lactic acid, D-lactic acid or a mixture thereof. In the ring-opening polymerization method, polylactic acid can be obtained using a selected catalyst while using lactide, which is a cyclic dimer of lactic acid, with a polymerization regulator or the like as necessary. In this case, the lactide includes L-lactide, which is a dimer of L-lactic acid, D-lactide, which is a dimer of D-lactic acid, or DL-lactide composed of L-lactic acid and D-lactic acid. If necessary, polylactic acid having an arbitrary composition and crystallinity can be obtained by mixing and polymerizing.

  The molecular weight of the polylactic acid used in the present invention is not particularly limited as long as it exhibits substantially sufficient mechanical properties when used in an intended application, for example, an injection molded product. When the molecular weight is low, the strength of the obtained molded product is lowered and the decomposition rate is increased. On the other hand, if it is high, the workability is lowered and molding becomes difficult. The preferred range of the weight average molecular weight of the polylactic acid used in the present invention is 50,000 to 400,000, more preferably 100,000 to 250,000.

  The polylactic acid used in the polylactic acid composition of the present invention may be a known commercial product, such as Mitsui Chemical Co., Ltd., trade name Lacia, Toyota Motor Corporation, trade name Eco Plastic (U'z), CargillDow. The product name NatureWorks etc. by Polymer LLC Ltd. are mentioned.

(Polylactic acid resin composition 1)
The polylactic acid resin composition according to the present invention is obtained by blending the polylactic acid as described above with a branched polylactic acid having at least three branched chains composed of polylactic acid in the molecule as described above. It is what.

  The addition amount of the branched polylactic acid in the polylactic acid composition of the present invention can be added to, for example, 0.1 to 50.0 parts by weight, preferably 1.0 to 100 parts by weight of polylactic acid. It is 30.0 weight part, More preferably, it is 5.0-20.0 weight part.

  The polylactic acid resin composition of the present invention can be produced, for example, by melt-mixing polylactic acid and branched polylactic acid. A polylactic acid composition can be obtained by heating and melting polylactic acid to a temperature equal to or higher than the melting point, adding branched polylactic acid, mixing by stirring or kneading, and cooling. The kneading can be carried out by mixing with a shearing force, and can be produced using a kneader, a rotating roll, an extruder or the like. For example, while melting polylactic acid using a twin screw extruder or the like, branched polylactic acid is poured and melt-kneaded, extruded into a strand shape, cooled, and pelletized by a pelletizer. The pellets thus produced can be sufficiently dried to remove moisture and then used for injection molding or the like.

  It can also be produced by mixing polylactic acid and branched polylactic acid roughly beforehand and then melt-mixing them.

  The melt mixing temperature is preferably not less than the melting point of polylactic acid and not more than 250 ° C. If it exceeds 250 ° C., depolymerization of polylactic acid occurs, leading to a decrease in molecular weight and physical properties.

  In the melt mixing, it is preferable to knead after sufficiently drying the polylactic acid in advance to remove moisture. If water is contained, there is a concern that it deteriorates due to hydrolysis of polylactic acid and branched polylactic acid during heating.

  In another embodiment, the polylactic acid resin composition of the present invention can be produced by dissolving and mixing polylactic acid and branched polylactic acid using a solvent.

  Examples of the dissolution solvent include, but are not limited to, chloroform, methylene chloride and the like. These solvents can be dissolved at room temperature.

  It can also be dissolved by heating in a solvent such as xylene, ethylbenzene, or mesitylene.

  For example, a polylactic acid composition can be produced by dissolving polylactic acid and branched polylactic acid in chloroform and then distilling off chloroform.

  In the polylactic acid composition of the present invention, branched polylactic acid is added to polylactic acid so that the branched polylactic acid blocks crystallization of the polylactic acid molecular chain and widens the molecular chain spacing. Flexibility is improved by making it easy. The tensile elongation at break is greatly increased by adding branched polylactic acid. That is, the toughness, particularly the low speed deformation toughness, is greatly improved. Thus, the polylactic acid composition of the present invention can add plasticity to conventional polylactic acid. Since branched polylactic acid is amorphous even if it has a relatively high molecular weight, it can be added without increasing the crystallinity, and bleeding can be suppressed. Further, since this blend is compatible at the molecular level and is stable, it is difficult for bleeding to occur on the surface (bleed). Furthermore, since the crystal size is small and the structure is similar, the refractive index is close and transparent.

  The effect of improving plasticization of the polylactic acid resin composition of the present invention can be confirmed by a change in mechanical properties. When polylactic acid is a very hard resin and uniaxially stretched alone, it breaks at a strain of about 20%, whereas in the case of the polylactic acid resin composition of the present invention, it is 100% to 700%. Break strain is observed. Thus, by mixing polylactic acid having a different molecular structure and branched polylactic acid, the plasticity of polylactic acid can be improved.

(Polylactic acid resin composition 2)
The second polylactic acid resin composition according to the present invention is characterized in that polylactic acid is melt-mixed with an oil and fat mainly composed of triacylglycerol having at least three epoxy groups in the molecule. It is.

  In the second polylactic acid resin composition, as described above, the branched polylactic acid in which the epoxy group of triacylglycerol is ring-opened and the carboxy terminal of polylactic acid is ester-bonded is contained in the polylactic acid. The triacylglycerol itself having at least three epoxy groups in the molecule is blended in polylactic acid.

  Even in the case where fats and oils mainly composed of triacylglycerol are melt-mixed in polylactic acid, the triacyl is not contained in the resin composition during the melt-mixing or the subsequent resin processing step. The terminal epoxy group of glycerol is ring-opened and reacts with the carboxy terminus of polylactic acid to form an ester bond, etc., so that it is almost the same as the polylactic acid resin composition comprising polylactic acid and branched polylactic acid. An effect is produced.

  The oil and fat mainly composed of triacylglycerol having at least three epoxy groups in the molecule used in the second polylactic acid resin composition is the same as described above, and the description thereof is omitted. . Also, the melt mixing conditions are substantially the same as those obtained when the polylactic acid is mixed with the branched polylactic acid to obtain a polylactic acid resin composition, and thus the description thereof is omitted.

  In addition, the addition amount of fats and oils mainly composed of triacylglycerol in the second polylactic acid resin composition is, for example, 0.1 to 50.0 parts by weight with respect to 100 parts by weight of polylactic acid. The amount is preferably 1.0 to 30.0 parts by weight, more preferably 5.0 to 20.0 parts by weight.

(Processing and application of polylactic acid resin composition)
The polylactic acid composition of the present invention is molded by any currently known molding method such as an injection molding method, a gas assist molding method, an injection compression molding method, an extrusion molding method, a blow molding method, a press molding method, or a vacuum / pressure forming method. can do. In addition to the above methods, an in-mold molding method, a gas press molding method, a two-color molding method, a sandwich molding method, PUSH-PULL, or the like can also be employed. As for molding conditions, in order to avoid thermal decomposition of the resin in the injection cylinder, it is preferable to mold the molten resin at a temperature range of 170 to 250 ° C.

  Polylactic acid is crystallized more than polyethylene terephthalate resin, which has a fairly rigid main chain and is generally considered to have a slow crystallization rate, as evidenced by its relatively high glass transition temperature of 57-60 ° C. The speed is slow. Therefore, in the injection molding not involving the stretching operation, even if the mold temperature is set to 90 to 100 ° C. optimal for crystallization (high temperature mold), it remains in a semi-molten state. Although it is finally cooled and solidified by setting the mold temperature to around room temperature (low temperature mold), the crystallinity is extremely low and only heat resistance is poor.

  On the other hand, the polylactic acid resin composition of the present invention has a high degree of crystallinity even in a low-temperature mold, and has higher heat resistance than conventional polylactic acid. Therefore, it is not necessary to take sufficient time for the crystallization (cooling) time, the molding cycle is shortened, and the productivity is improved.

  The improvement of the crystallization promoting effect of the polylactic acid resin composition of the present invention can be confirmed by a change in thermal characteristics. When polylactic acid was heated and melted at 200 ° C. and held for 10 minutes, the crystallization enthalpy when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured by a differential scanning calorimeter (DSC). In contrast, in the case of the composition of the polylactic acid and the branched polylactic acid of the present invention, a crystallinity of several to 50% was observed. The polylactic acid resin composition of the present invention is a polylactic acid that is very easy to crystallize against polylactic acid, which is a crystalline polymer but very difficult to crystallize, and heat resistance is improved by increasing crystallinity. .

  In addition, the degree of crystallinity can be further increased by crystallizing the polylactic acid resin composition of the present invention by some method at the time of molding or after molding. For example, crystallization can be achieved by a method in which a melt of a composition is filled in a mold at the time of molding and crystallized as it is in a high-temperature mold, and a method in which an amorphous molded product of the composition is subjected to dry heat treatment or wet heat treatment. Can be improved.

  Since the polylactic acid resin composition of the present invention can be melt-kneaded, it can be processed into various molded products and used by methods such as injection molding and extrusion molding. As molded products, they can be used as injection molded products, extrusion molded products, blow molded products, films, fibers, sheets, and the like. The film can be used as various films such as unstretched, uniaxially stretched, biaxially stretched, and blown film, and the fiber can be used as various fibers such as unstretched yarn, stretched yarn, and superstretched yarn. In addition, these articles can be used for various applications such as electric / electronic parts, building members, automobile parts, and daily necessities.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, the scope of the present invention is not limited to these illustrations.

Example 1
To 100 parts by mass of L-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.), 31 parts by mass of castor oil (manufactured by Wako Pure Chemical Industries, Ltd.) as an initiator was added and mixed. Under an argon atmosphere, tin 2-ethylhexanoate was added. As a catalyst, it heated at 130 degreeC for 24 hours, and obtained the polymer. The obtained polymer was subjected to H1-NMR measurement to confirm the structure. In all cases, the peak derived from methine adjacent to the hydroxyl group of castor oil disappeared, and it was confirmed that a star-shaped branched polyester polyol having the hydroxyl group of castor oil as the starting point was synthesized. When the molecular weight of the obtained polyester polyol was also determined by H1-NMR, it was a number average molecular weight of 3,200. Also, since the molecular weight calculated from the H1-NMR and the molecular weight calculated from the charge ratio were in good agreement, a polylactic acid homopolymer was not produced, and only branched polylactic acid using castor oil as an initiator was obtained. I understood it.

  5 parts by mass of this branched polylactic acid was mixed with 95 parts by mass of polylactic acid (weight average molecular weight 150,000) dissolved in chloroform. This mixture was dried to obtain a sheet-like sample. This sample was transparent. When this sample was subjected to a uniaxial extension test, an elongation at break of 182% was observed.

(Example 2)
A sheet-like sample of the polylactic acid composition was obtained in the same manner as in Example 1 except that D-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of L-lactide. This sample was also transparent. When this sample was subjected to a uniaxial extension test, an elongation at break of 699% was observed.

(Example 3)
A sheet-like sample of the polylactic acid composition was obtained in the same manner as in Example 1 except that DL-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of L-lactide. This sample was also transparent. When this sample was subjected to a uniaxial extension test, 214% elongation at break was observed.

(Comparative Example 1)
Polylactic acid (weight average molecular weight 150,000) was dissolved in chloroform and then dried to obtain a sheet-like sample. This sample was transparent. When this sample was subjected to a uniaxial extension test, it showed only 20% elongation at break.

Example 4
To 100 parts by mass of L-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.), 12 parts by mass of castor oil (manufactured by Wako Pure Chemical Industries, Ltd.) as an initiator is added and mixed. Under an argon atmosphere, tin 2-ethylhexanoate is added. As a catalyst, it heated at 130 degreeC for 24 hours, and obtained the polymer. The obtained polymer was subjected to H1-NMR measurement to confirm the structure. In all cases, the peak derived from methine adjacent to the hydroxyl group of castor oil disappeared, and it was confirmed that a star-shaped branched polyester polyol having the hydroxyl group of castor oil as the starting point was synthesized. When the molecular weight of the obtained polyester polyol was also determined by H1-NMR, it was a number average molecular weight of 8,000. Also, since the molecular weight calculated from the H1-NMR and the molecular weight calculated from the charge ratio were in good agreement, a polylactic acid homopolymer was not produced, and only branched polylactic acid using castor oil as an initiator was obtained. I understood it.

  5 parts by mass of this branched polylactic acid was mixed with 95 parts by mass of polylactic acid (weight average molecular weight 150,000) dissolved in chloroform. This mixture was dried to obtain a sheet-like sample. This sample was transparent. When this sample was subjected to a uniaxial extension test, 110% elongation at break was observed.

(Example 5)
To 100 parts by mass of L-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.), 31 parts by mass of polycastor oil (manufactured by Ito Oil Co., Ltd.) as an initiator was added and mixed. Under an argon atmosphere, tin 2-ethylhexanoate was used as a catalyst. And heated at 130 ° C. for 24 hours to obtain a polymer. The obtained polymer was subjected to H1-NMR measurement to confirm the structure. In all cases, the peak derived from methine adjacent to the hydroxyl group of castor oil disappeared, and it was confirmed that a star-shaped branched polyester polyol having the hydroxyl group of castor oil as the starting point was synthesized. When the molecular weight of the obtained polyester polyol was also determined by H1-NMR, it was a number average molecular weight of 4,200. Also, since the molecular weight calculated from the H1-NMR and the molecular weight calculated from the charge ratio were in good agreement, a polylactic acid homopolymer was not produced, and only branched polylactic acid using castor oil as an initiator was obtained. I understood it.

  5 parts by mass of this branched polylactic acid was mixed with 95 parts by mass of polylactic acid (weight average molecular weight 150,000) dissolved in chloroform. This mixture was dried to obtain a sheet-like sample. This sample was transparent. When this sample was subjected to a uniaxial extension test, 214% elongation at break was observed.

(Example 6)
A sheet-like sample of the polylactic acid composition was obtained in the same manner as in Example 5 except that D-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of L-lactide. This sample was also transparent. When this sample was subjected to a uniaxial extension test, a breaking elongation of 713% was observed.

(Example 7)
Dehydrated lactic acid 90 obtained by heating 9.5 parts by mass of epoxidized soybean oil as an initiator (manufactured by ADEKA Corporation) and L-lactic acid (manufactured by Wako Pure Chemical Industries, Ltd., 90 v / v% aqueous solution) under reduced pressure. Then, 2-ethylhexanoic acid tin was added as a catalyst in a nitrogen atmosphere and heated at 150 ° C. for 5 hours. Subsequently, the pressure was maintained for 2 hours under a reduced pressure of 13000 Pa, 2 hours under a reduced pressure of 4000 Pa, 2 hours under a reduced pressure of 2600 Pa, and then 1300 Pa. Furthermore, it heated at 180 degreeC for 2 hours, hold | maintaining the reduced pressure of 1300 Pa. When the molecular weight was also determined by gel permeation chromatography (GPC), the number average molecular weight was 8,000, and the molecular weight calculated from the charge ratio was in good agreement. It was found that only branched polylactic acid using bean oil as an initiator was obtained.

  5 parts by mass of this branched polylactic acid was melt mixed with 95 parts by mass of polylactic acid (weight average molecular weight 150,000) at 190 ° C. in a nitrogen atmosphere. The sample was heated and melted at 200 ° C. and held for 10 minutes, and then the amount of crystallization when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured. Moreover, after cooling to -100 degreeC, the heat of fusion observed when heating to 200 degreeC again was measured. When the relative crystallization rate during cooling after melting was calculated from the ratio of the crystallization heat amount to the heat of fusion, the relative crystallization rate was about 65%.

(Example 8)
Dehydration obtained by heating 9.1 parts by weight of hydrogenated castor oil (Wako Pure Chemical Industries, Ltd.) and L-lactic acid (Wako Pure Chemical Industries, 90 v / v% aqueous solution) under reduced pressure. 90 parts by mass of lactic acid was mixed, tin 2-ethylhexanoate was added as a catalyst in a nitrogen atmosphere, and the mixture was heated at 150 ° C. for 5 hours. Subsequently, the pressure was maintained for 2 hours under a reduced pressure of 13000 Pa, 2 hours under a reduced pressure of 4000 Pa, 2 hours under a reduced pressure of 2600 Pa, and then 1300 Pa. Furthermore, it heated at 180 degreeC for 2 hours, hold | maintaining the reduced pressure of 1300 Pa. When the molecular weight was also determined by gel permeation chromatography (GPC), the number average molecular weight was 8,000, and the molecular weight calculated from the charge ratio was in good agreement, so a polylactic acid homopolymer was not produced, and castor oil was used. It was found that only branched polylactic acid as an initiator was obtained.

  10 parts by mass of this branched polylactic acid was melt mixed with 90 parts by mass of polylactic acid (weight average molecular weight 150,000) at 190 ° C. in a nitrogen atmosphere. The sample was heated and melted at 200 ° C. and held for 10 minutes, and then the amount of crystallization when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured. Moreover, after cooling to -100 degreeC, the heat of fusion observed when heating to 200 degreeC again was measured. When the relative crystallization rate at the time of cooling after melting was calculated from the ratio of the crystallization heat amount to the heat of fusion, the relative crystallization rate was about 57%.

Example 9
Dehydrated lactic acid obtained by heating 9.1 parts by weight of castor oil (manufactured by Wako Pure Chemical Industries, Ltd.) as an initiator and L-lactic acid (manufactured by Wako Pure Chemical Industries, Ltd., 90 v / v% aqueous solution) under reduced pressure. 90 parts by mass was mixed, and in a nitrogen atmosphere, tin 2-ethylhexanoate was added as a catalyst and heated at 150 ° C. for 5 hours. Subsequently, the pressure was maintained for 2 hours under a reduced pressure of 13000 Pa, 2 hours under a reduced pressure of 4000 Pa, 2 hours under a reduced pressure of 2600 Pa, and then 1300 Pa. Furthermore, it heated at 180 degreeC for 2 hours, hold | maintaining the reduced pressure of 1300 Pa. When the molecular weight was also determined by gel permeation chromatography (GPC), the number average molecular weight was 8,000, and the molecular weight calculated from the charge ratio was in good agreement, so a polylactic acid homopolymer was not produced, and castor oil was used. It was found that only branched polylactic acid as an initiator was obtained. Next, acetic anhydride was added to the branched polylactic acid and heated in pyridine at 80 ° C. for 1 hour. The obtained pyridine solution was dropped into distilled water, and the precipitated white powder was collected to obtain branched polylactic acid in which hydrogen at the terminal hydroxyl group was substituted with an acetyl group.

  20 parts by mass of this branched polylactic acid was melt-mixed with 190 parts by mass of polylactic acid (weight average molecular weight 150,000) at 190 ° C. in a nitrogen atmosphere. The sample was heated and melted at 200 ° C. and held for 10 minutes, and then the amount of crystallization when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured. Moreover, after cooling to -100 degreeC, the heat of fusion observed when heating to 200 degreeC again was measured. When the relative crystallization rate at the time of cooling after melting was calculated from the ratio of the crystallization heat amount to the heat of fusion, the relative crystallization rate was about 37%.

(Example 10)
Dehydrated lactic acid obtained by heating 9.1 parts by weight of castor oil (manufactured by Wako Pure Chemical Industries, Ltd.) as an initiator and L-lactic acid (manufactured by Wako Pure Chemical Industries, Ltd., 90 v / v% aqueous solution) under reduced pressure. 90 parts by mass was mixed, and in a nitrogen atmosphere, tin 2-ethylhexanoate was added as a catalyst and heated at 150 ° C. for 5 hours. Subsequently, the pressure was maintained for 2 hours under a reduced pressure of 13000 Pa, 2 hours under a reduced pressure of 4000 Pa, 2 hours under a reduced pressure of 2600 Pa, and then 1300 Pa. Furthermore, it heated at 180 degreeC for 2 hours, hold | maintaining the reduced pressure of 1300 Pa. When the molecular weight was also determined by gel permeation chromatography (GPC), the number average molecular weight was 8,000, and the molecular weight calculated from the charge ratio was in good agreement, so a polylactic acid homopolymer was not produced, and castor oil was used. It was found that only branched polylactic acid as an initiator was obtained. Next, phthalic anhydride was added to this branched polylactic acid and heated in pyridine at 95 ° C. for 1 hour. The resulting pyridine solution was neutralized with an aqueous sodium hydroxide solution. The white powder precipitated by neutralization is collected by centrifugal sedimentation. Further, washing was performed to obtain a branched polylactic acid having a terminal hydroxyl group ester-bonded to sodium phthalate.

  10 parts by mass of this branched polylactic acid was melt mixed with 90 parts by mass of polylactic acid (weight average molecular weight 150,000) at 190 ° C. in a nitrogen atmosphere. The sample was heated and melted at 200 ° C. and held for 10 minutes, and then the amount of crystallization when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured. Moreover, after cooling to -100 degreeC, the heat of fusion observed when heating to 200 degreeC again was measured. When the relative crystallization rate at the time of cooling after melting was calculated from the ratio of the crystallization heat amount to the heat of fusion, the relative crystallization rate was about 86%.

(Example 11)
Dehydration obtained by heating 9.1 parts by weight of hardened castor oil (Wako Pure Chemical Industries, Ltd.) and DL-lactic acid (Wako Pure Chemical Industries, 90 v / v% aqueous solution) under reduced pressure. 90 parts by mass of lactic acid was mixed, tin 2-ethylhexanoate was added as a catalyst in a nitrogen atmosphere, and the mixture was heated at 150 ° C. for 5 hours. Subsequently, the pressure was maintained for 2 hours under a reduced pressure of 13000 Pa, 2 hours under a reduced pressure of 4000 Pa, 2 hours under a reduced pressure of 2600 Pa, and then 1300 Pa. Furthermore, it heated at 180 degreeC for 2 hours, hold | maintaining the reduced pressure of 1300 Pa. When the molecular weight was also determined by gel permeation chromatography (GPC), the number average molecular weight was 8,000, and the molecular weight calculated from the charge ratio was in good agreement, so a polylactic acid homopolymer was not produced, and castor oil was used. It was found that only branched polylactic acid as an initiator was obtained.

  5 parts by mass of this branched polylactic acid was melt mixed with 95 parts by mass of polylactic acid (weight average molecular weight 150,000) at 190 ° C. in a nitrogen atmosphere. The sample was heated and melted at 200 ° C. and held for 10 minutes, and then the amount of crystallization when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured. Moreover, after cooling to -100 degreeC, the heat of fusion observed when heating to 200 degreeC again was measured. When the relative crystallization rate at the time of cooling after melting was calculated from the ratio of the crystallization heat amount to the heat of fusion, the relative crystallization rate was about 65.6%.

Example 12
90 parts by weight of dehydrated lactic acid obtained by heating 9.1 parts by weight of hydrogenated castor oil as an initiator (manufactured by Wako Pure Chemical Industries, Ltd.) and D-lactic acid (manufactured by Purec, 90 v / v% aqueous solution) under reduced pressure Then, 2-ethylhexanoic acid tin was added as a catalyst under a nitrogen atmosphere and heated at 150 ° C. for 5 hours. Subsequently, the pressure was maintained for 2 hours under a reduced pressure of 13000 Pa, 2 hours under a reduced pressure of 4000 Pa, 2 hours under a reduced pressure of 2600 Pa, and then 1300 Pa. Furthermore, it heated at 180 degreeC for 2 hours, hold | maintaining the reduced pressure of 1300 Pa. When the molecular weight was also determined by gel permeation chromatography (GPC), the number average molecular weight was 8,000, and the molecular weight calculated from the charge ratio was in good agreement, so a polylactic acid homopolymer was not produced, and castor oil was used. It was found that only branched polylactic acid as an initiator was obtained.

  20 parts by mass of this branched polylactic acid was melt-mixed with 190 parts by mass of polylactic acid (weight average molecular weight 150,000) at 190 ° C. in a nitrogen atmosphere. The sample was heated and melted at 200 ° C. and held for 10 minutes, and then the amount of crystallization when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured. Moreover, after cooling to -100 degreeC, the heat of fusion observed when heating to 200 degreeC again was measured. When the relative crystallization rate at the time of cooling after melting was calculated from the ratio of the crystallization heat amount to the heat of fusion, the relative crystallization rate was about 64.7%.

(Example 13)
Dehydrated lactic acid obtained by heating 9.1 parts by weight of castor oil (manufactured by Wako Pure Chemical Industries, Ltd.) as an initiator and L-lactic acid (manufactured by Wako Pure Chemical Industries, Ltd., 90 v / v% aqueous solution) under reduced pressure. 90 parts by mass was mixed, and in a nitrogen atmosphere, tin 2-ethylhexanoate was added as a catalyst and heated at 150 ° C. for 5 hours. Subsequently, the pressure was maintained for 2 hours under a reduced pressure of 13000 Pa, 2 hours under a reduced pressure of 4000 Pa, 2 hours under a reduced pressure of 2600 Pa, and then 1300 Pa. Furthermore, it heated at 180 degreeC for 2 hours, hold | maintaining the reduced pressure of 1300 Pa. When the molecular weight was also determined by gel permeation chromatography (GPC), the number average molecular weight was 8,000, and the molecular weight calculated from the charge ratio was in good agreement, so a polylactic acid homopolymer was not produced, and castor oil was used. It was found that only branched polylactic acid as an initiator was obtained. Next, benzoic anhydride was added to this branched polylactic acid and heated in pyridine at 80 ° C. for 1 hour. The obtained pyridine solution was dropped into distilled water, and the precipitated white powder was recovered to obtain branched polylactic acid in which hydrogen at the terminal hydroxyl group was substituted with benzoic acid.

  20 parts by mass of this branched polylactic acid was melt-mixed with 190 parts by mass of polylactic acid (weight average molecular weight 150,000) at 190 ° C. in a nitrogen atmosphere. The sample was heated and melted at 200 ° C. and held for 10 minutes, and then the amount of crystallization when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured. Moreover, after cooling to -100 degreeC, the heat of fusion observed when heating to 200 degreeC again was measured. When the relative crystallization rate at the time of cooling after melting was calculated from the ratio of the crystallization heat amount to the heat of fusion, the relative crystallization rate was about 43.9%.

(Comparative Example 2)
After polylactic acid (weight average molecular weight 150,000) was heated and melted at 200 ° C. and held for 10 minutes, the heat of crystallization when the temperature was lowered to 20 ° C. at a rate of 10 ° C. per minute was measured. Moreover, after cooling to -100 degreeC, the heat of fusion observed when heating to 200 degreeC again was measured. When the relative crystallization rate at the time of cooling after melting was calculated from the ratio of the crystallization heat amount to the heat of fusion, the relative crystallization rate was about 1.4%.

  The polylactic acid composition comprising the multi-branched polylactic acid and the polylactic acid according to the present invention has an unprecedented flexibility so that it can be used as a film, etc. The use of office supplies, miscellaneous goods, daily necessities, etc. is expected to expand, and because of its excellent heat resistance, it is expected to expand its use to automobiles, home appliances, and other industrial products that require heat resistance. Furthermore, the polylactic acid plastic produced according to the present invention is derived from both the base resin and the branched polylactic acid to be added, and is expected to prevent global warming by reducing carbon dioxide and to save resources by removing petroleum. The

It is a schematic diagram which shows one Embodiment of the synthesis | combination and structure of the polyester polyol of this invention. It is a schematic diagram which shows other embodiment of the synthesis | combination and structure of the polyester polyol of this invention.

Claims (12)

  A polylactic acid resin composition comprising polylactic acid and branched polylactic acid having at least three branched chains composed of polylactic acid in a molecule.   2. The polylactic acid resin composition according to claim 1, wherein the branched polylactic acid is polylactic acid obtained by polymerizing an oil whose main component is triacylglycerol having at least three hydroxyl groups in the molecule as an initiator.   The polylactic acid resin composition according to claim 2, wherein the fat is castor oil, polycastor oil, hydrogenated castor oil, or hydroxylated soybean oil.   2. The polylactic acid resin composition according to claim 1, wherein the branched polylactic acid is polylactic acid obtained by polymerizing an oil whose main component is triacylglycerol having at least three epoxy groups in the molecule as an initiator.   The polylactic acid resin composition according to claim 4, wherein the fat is epoxidized soybean oil, epoxidized palm oil, or epoxidized linseed oil.   The polylactic acid according to claim 1, wherein 1 to 30 parts by weight of branched polylactic acid having at least three branched chains composed of polylactic acid in the molecule is added to 100 parts by weight of polylactic acid. Resin composition.   The polylactic acid resin composition according to claim 1, wherein the branched chain in the branched polylactic acid comprises D-lactic acid or DL-lactic acid as a structural unit.   The polylactic acid resin composition according to claim 1, wherein the polylactic acid resin composition is a branched polylactic acid in which hydrogen at a terminal hydroxyl group of the branched polylactic acid is substituted with an acyl group.   The polylactic acid resin composition according to claim 1, which is a branched polylactic acid in which a terminal hydroxyl group of the branched polylactic acid is ester-bonded to a dicarboxylic acid.   The polylactic acid resin composition according to claim 9, wherein in the dicarboxylic acid, a carboxyl group that does not form an ester bond with a terminal hydroxyl group of the branched polylactic acid forms a salt with a cation.   A resin composition obtained by melting and mixing oil and fat mainly composed of triacylglycerol having at least three epoxy groups in a molecule with polylactic acid.   An additive for polylactic acid resin, which is branched polylactic acid having at least three branched chains composed of polylactic acid in the molecule.

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