JP2009155531A - Resin composition, preparation method, and film including the resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition containing an aliphatic polyester resin, which is excellent in mechanical characteristic and biodegradability, particularly, a resin composition which provides a film which has high tearing strength and satisfactory biodegradability, moldability, heat-shrinkable property and transparency, and is wrinkle-resistant with high elastic modulus. <P>SOLUTION: The resin composition contains an aliphatic polyester resin (A) consisting mainly of an aliphatic dicarboxylic acid and an aliphatic diol; an araliphatic polyester resin (B); starch (C); and a polyvalent alcohol (D), with (A)/[(A)+(B)]=0.30-0.95, (C)/[(A)+(B)]=0.05-0.50, (D)/[(A)+(B)+(C)]=0.0001-0.05 by mass ratio. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin composition and a film comprising the resin composition. In detail, it is related with the biodegradable film which can be used for uses, such as an agricultural film, a garbage bag, a compost bag, a shopping bag, a shopping bag, a food packaging material, a foodstuff container, and the resin composition for forming this.

  Conventionally, paper, plastic film, aluminum foil, etc. have been used in a wide range of applications such as packaging materials, agricultural materials, and building materials for packaging liquids, powders, and solids of various foods, medicines, miscellaneous goods, etc. Has been. Among these, in particular, the plastic film is excellent in strength, water resistance, moldability, transparency, cost, and the like, and is used in many applications as a bag or a container.

  Examples of the plastic constituting the plastic film include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. However, since these plastic films are produced from petroleum-derived raw materials, there are problems of depletion of fossil resources and problems that lead to global warming due to the generation of carbon dioxide during incineration when discarded. Moreover, since most plastics are durable in the environment, their shapes are maintained when discarded, and waste problems such as environmental pollution and a shortage of landfill are becoming serious.

  In recent years, for the purpose of solving the above problems, plant-derived raw materials, resins produced from plants, and biodegradable resins have been used. Many researches have been made on plant-derived resin raw materials, and typical examples of plant-derived resin raw materials include aliphatic polyesters such as polylactic acid, polybutylene succinate, polybutylene succinate adipate, and the like.

  Examples of the biodegradable resin include aliphatic polyesters such as polylactic acid, polybutylene succinate, polybutylene succinate adipate, and polycaprolactone. However, these aliphatic polyesters are biodegradable, but have insufficient mechanical properties such as tear strength of the film (Patent Document 1).

  As a technique for solving these problems, an attempt was made to control physical properties by using a mixture of an aliphatic aromatic polyester resin and starch (Patent Document 2). However, even when the biodegradable aliphatic aromatic polyester resin and starch are mixed, there are problems that the tear strength is improved but the biodegradation rate is slow, the elastic modulus is low, and the rigidity is insufficient. In general, when the elastic modulus of the film is increased, wrinkles are likely to occur and the appearance of the film tends to deteriorate.

JP-A-8-239461 JP-T 6-502676

  The present invention has been made in view of the above-described background art, and its problems are strong tear strength, good biodegradability, moldability, heat shrinkability, transparency, high elasticity, and less tendency to wrinkle. To get a film.

  As a result of intensive studies to solve the above problems, the present inventor has obtained an aliphatic polyester resin (A), an aromatic aliphatic polyester resin (B), starch (C), and a polyhydric alcohol (D). It has been found that the above-mentioned problems can be solved by including a specific mass ratio, and that the above-mentioned problems can be solved by mixing in a specific order, and the present invention has been completed.

That is, the present invention provides an aliphatic polyester resin (A), an aromatic aliphatic polyester resin (B), a starch (C), and a polyhydric alcohol (D) mainly composed of an aliphatic dicarboxylic acid and an aliphatic diol. Including, by mass ratio,
(A) / [(A) + (B)] = 0.30-0.95,
(C) / [(A) + (B)] = 0.05-0.50,
(D) / [(A) + (B) + (C)] = 0.0001-0.05
The present invention provides a resin composition characterized by the above.

  The present invention also provides a method for producing the above resin composition, comprising mixing the aliphatic polyester-based resin (A) after mixing the aromatic aliphatic polyester-based resin (B) and the starch (C), and The resin composition manufactured using the manufacturing method is provided.

  The present invention also provides a film comprising the resin composition as a main component.

  ADVANTAGE OF THE INVENTION According to this invention, the resin composition excellent in the moldability can be provided by mixing aliphatic polyester-type resin (A), aromatic aliphatic polyester-type resin (B), etc. in a specific ratio. . In addition, a molded body containing the resin composition as a main component, particularly a film, can be made excellent in tear strength, moldability, heat shrinkability, transparency, biodegradability, etc., and has a high elastic modulus. Can be difficult. For this reason, the molded body, particularly film, should be widely used in packaging materials, agricultural materials, building materials, etc. for packaging various foods, medicines, miscellaneous liquids, powders or solids. Can do.

  Hereinafter, the present invention will be described. However, the present invention is not limited to the specific embodiments described below, and includes modifications that are arbitrarily modified within the technical scope of the present invention.

<Aliphatic polyester resin (A)>
In the present invention, the “aliphatic polyester resin (A)” refers to a polyester resin that has substantially no aromatic ring in the molecule. The “aliphatic polyester resin” in the present invention contains an aliphatic dicarboxylic acid and an aliphatic diol as main components. Here, the “main component” refers to 50 mol% or more, preferably 80 mol of an aliphatic diol and an aliphatic dicarboxylic acid based on the whole monomer unit constituting the aliphatic polyester resin (100 mol%). % Or more, more preferably 90 mol% or more.

  Specific examples of the aliphatic polyester-based resin (A) in the present invention include, for example, chain aliphatic and / or alicyclic diol units represented by the following formula (1), and the following formula (2). A chain aliphatic and / or alicyclic dicarboxylic acid unit represented by However, the aliphatic oxycarboxylic acid unit mentioned later may be contained.

—O—R ¹ —O— (1)
[In the formula (1), R ¹ represents a divalent chain aliphatic hydrocarbon group and / or a divalent alicyclic hydrocarbon group. When copolymerized, two or more types of R ¹ may be contained in the resin. ]
^-OC-R 2 -CO- (2)
[In the formula (2), R ² represents a divalent chain aliphatic hydrocarbon group and / or a divalent alicyclic hydrocarbon group. When copolymerized, two or more types of R ² may be contained in the resin. ]

  In the above formulas (1) and (2), “and” in the “divalent chain aliphatic hydrocarbon group and / or divalent alicyclic hydrocarbon group” means an aliphatic polyester resin. It means that both a divalent chain aliphatic hydrocarbon group and a divalent alicyclic hydrocarbon group may be contained in one molecule of (A). Hereinafter, “chain aliphatic and / or alicyclic” may be simply abbreviated as “aliphatic”.

  The aliphatic diol component giving the diol unit of the formula (1) is not particularly limited, but an aliphatic diol component having 2 to 10 carbon atoms is preferable, and an aliphatic diol component having 4 to 6 carbon atoms is particularly preferable. Specific examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and 1,4-butanediol is particularly preferable. Two or more types of aliphatic diol components can be used.

  The aliphatic dicarboxylic acid component giving the dicarboxylic acid unit of the formula (2) is not particularly limited, but an aliphatic dicarboxylic acid component having 2 to 10 carbon atoms is preferable, and an aliphatic dicarboxylic acid component having 4 to 8 carbon atoms is particularly preferable. preferable. Specific examples include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, etc. Among them, succinic acid or adipic acid is particularly preferable. Two or more types of aliphatic dicarboxylic acid components can be used.

  Further, the aliphatic polyester resin (A) may contain an aliphatic oxycarboxylic acid unit. Specific examples of the aliphatic oxycarboxylic acid that gives an aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3, Examples include 3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, and the like, or lower alkyl esters or intramolecular esters thereof. When optical isomers exist in these, any of D-form, L-form and racemic form may be sufficient, and a form may be any of solid, liquid, or aqueous solution. Of these, lactic acid or glycolic acid is particularly preferred. These aliphatic oxycarboxylic acids can be used alone or as a mixture of two or more.

  The amount of the aliphatic oxycarboxylic acid is usually at least 0 mol%, preferably 0.01 mol%, based on the whole monomer component constituting the aliphatic polyester resin (A) (100 mol%). The upper limit is usually 30 mol% or less, preferably 20 mol% or less.

  The aliphatic polyester resin (A) is composed of “a trifunctional or higher aliphatic polyhydric alcohol”, “a trifunctional or higher aliphatic polyvalent carboxylic acid or acid anhydride thereof” or “a trifunctional or higher aliphatic polyhydric alcohol”. It is preferable to copolymerize "valent oxycarboxylic acid" because the melt viscosity of the resulting aliphatic polyester resin (A) can be increased.

  Specific examples of the trifunctional aliphatic polyhydric alcohol include trimethylolpropane and glycerin. Specific examples of the tetrafunctional aliphatic polyhydric alcohol include pentaerythritol. These may be used alone or in combination of two or more.

  Specific examples of the trifunctional aliphatic polyvalent carboxylic acid or its acid anhydride include propanetricarboxylic acid or its acid anhydride. Specific examples of the tetrafunctional polyvalent carboxylic acid or its acid anhydride include cyclopentanetetracarboxylic acid or its acid anhydride. These may be used alone or in combination of two or more.

  In addition, the trifunctional aliphatic oxycarboxylic acid includes (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) one carboxyl group and two hydroxyl groups. Any type can be used. Specifically, malic acid or the like is preferably used. In addition, the tetrafunctional aliphatic oxycarboxylic acid includes (i) a type in which three carboxyl groups and one hydroxyl group are shared in the same molecule, and (ii) two carboxyl groups and two hydroxyl groups. And (iii) a type in which three hydroxyl groups and one carboxyl group are shared in the same molecule, and any type can be used. Specific examples include citric acid and tartaric acid. These may be used alone or in combination of two or more.

  The amount of such a tri- or higher functional compound is usually 0 mol% or more, preferably 0.01 mol, based on the total monomer constituting the aliphatic polyester resin (A) (100 mol%). The upper limit is usually 5 mol% or less, preferably 2.5 mol% or less.

  As the aliphatic polyester resin (A), it is particularly preferable to use a polybutylene succinate adipate resin and / or a polybutylene succinate adipate resin.

  The aliphatic polyester resin (A) used in the present invention can be produced by a known method. For example, a general method of melt polymerization in which an esterification reaction and / or a transesterification reaction between the aliphatic dicarboxylic acid component and the aliphatic diol component is performed, followed by a polycondensation reaction under reduced pressure, It can also be produced by a known solution heating dehydration condensation method using a solvent. Among these, from the viewpoint of economy and simplicity of the production process, a method of production by melt polymerization performed in the absence of a solvent is preferable.

  The polycondensation reaction is preferably performed in the presence of a polymerization catalyst. The addition timing of the polymerization catalyst is not particularly limited as long as it is before the polycondensation reaction, and it may be added when the raw materials are charged, or may be added at the start of pressure reduction. The polymerization catalyst is generally a compound containing a group 1 to group 15 metal element excluding hydrogen and carbon in the periodic table. Specifically, at least one metal selected from the group consisting of titanium, zirconium, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, strontium, sodium, and potassium. A carboxylate-containing salt, an alkoxy salt, an organic sulfonate, a compound containing an organic group such as a β-diketonate complex, an inorganic compound such as an oxide of a metal or a halide described above, or a mixture thereof.

  In these, the metal compound containing titanium, a zirconium, germanium, zinc, aluminum, magnesium, or calcium, and those mixtures are preferable, and especially a titanium compound or a germanium compound is preferable. In addition, when the catalyst is in a melted or dissolved state at the time of polymerization, the polymerization rate is increased. Therefore, the catalyst is preferably a liquid at the time of polymerization or a compound that is soluble in an ester low polymer or polyester.

  The amount of catalyst added in the case of using a metal compound as the polymerization catalyst, the lower limit is usually 5 ppm or more, preferably 10 ppm or more, and the upper limit is usually 30000 ppm or less, preferably 1000 ppm or less, as the amount of metal relative to the produced polyester. More preferably, it is 250 ppm or less, Especially preferably, it is 130 ppm or less. If too much catalyst is used, it is not only economically disadvantageous but also lowers the thermal stability of the polymer. Conversely, if it is too little, the polymerization activity is lowered, and as a result, the polymer decomposes during polymer production. Is more likely to be triggered.

  The lower limit of the esterification reaction and / or transesterification reaction temperature between the dicarboxylic acid component and the diol component is usually 150 ° C or higher, preferably 180 ° C or higher, and the upper limit is usually 260 ° C or lower, preferably 250 ° C or lower. The reaction atmosphere is usually an inert gas atmosphere such as nitrogen or argon. The reaction pressure is usually normal pressure to 10 kPa, and normal pressure is preferred. The reaction time is usually 1 hour or longer, and the upper limit is usually 10 hours or shorter, preferably 4 hours or shorter.

In the subsequent polycondensation reaction, the lower limit of the pressure is usually 0.001 × 10 ³ Pa or more, preferably 0.01 × 10 ³ Pa or more, and the upper limit is usually 1.4 × 10 ³ Pa or less, preferably 0. The degree of vacuum is 4 × 10 ³ Pa or less. At this time, the lower limit of the reaction temperature is usually 150 ° C. or higher, preferably 180 ° C. or higher, and the upper limit is usually 260 ° C. or lower, preferably 250 ° C. or lower. The lower limit of the reaction time is usually 2 hours or more, and the upper limit is usually 15 hours or less, preferably 10 hours or less.

  As a reaction apparatus for producing the aliphatic polyester-based resin (A), a known vertical or horizontal stirred tank reactor can be used. For example, melt polymerization is performed in two stages of esterification and / or transesterification and reduced pressure polycondensation using the same or different reactors, and a vacuum pump and a reactor are used as the reduced pressure polycondensation reactor. A method using a stirred tank reactor equipped with a evacuating pipe for decompression to be connected can be mentioned. In addition, a condenser is connected between the vacuum exhaust pipe connecting the vacuum pump and the reactor, and the volatile components and unreacted monomers generated during the condensation polymerization reaction are recovered by the condenser. Is preferred.

  In the present invention, the molar ratio of the diol component and the dicarboxylic acid component for obtaining the aliphatic polyester resin (A) having the desired degree of polymerization is different depending on the purpose and the kind of raw material, but the acid component 1 The lower limit of the amount of the diol component relative to mol is usually 0.8 mol or more, preferably 0.9 mol or more, and the upper limit is usually 1.5 mol or less, preferably 1.3 mol or less, particularly preferably 1. 2 mol or less. Moreover, a urethane bond, an amide bond, a carbonate bond, an ether bond, etc. can be introduce | transduced into an aliphatic polyester-type resin (A) in the range which does not affect biodegradability.

  The aliphatic polyester resin (A) used in the present invention has a sufficiently high crystallization rate, and the half-value width of the exothermic peak based on crystallization when cooled at 10 ° C./min in the differential scanning calorimeter measurement. Usually, it is 15 ° C. or less, preferably 10 ° C. or less, particularly preferably 8 ° C. or less. The differential scanning calorimeter is measured by using, for example, a Perkin Elmer DSC7, 10 mg of a sample is heated and melted in a nitrogen stream at a flow rate of 50 mL / min, cooled at a rate of 10 ° C./min, and accompanied with crystallization. This is done by recording the exothermic peak.

  The melt flow rate (MFR) of the aliphatic polyester resin (A) used in the present invention has a lower limit of usually 0.1 g / 10 min when measured at 190 ° C. and 2.16 kg. 5 g / 10 min, more preferably 1.0 g / 10 min, and most preferably 2.0 g / 10 min. The upper limit of MFR is usually 100 g / 10 minutes, preferably 50 g / 10 minutes, more preferably 30 g / 10 minutes, and most preferably 10 g / 10 minutes.

<Aromatic aliphatic polyester resin (B)>
The resin composition of the present invention contains an aromatic aliphatic polyester resin (B) mainly composed of an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, and an aliphatic diol. In this case, the content of the aromatic dicarboxylic acid unit is preferably 5 mol% or more and 60 mol% or less based on the total amount of the aliphatic dicarboxylic acid unit and the aromatic dicarboxylic acid unit (100 mol%). Specifically, for example, an aliphatic diol unit represented by the following formula (3), an aliphatic dicarboxylic acid unit represented by the following formula (4), and an aroma represented by the following formula (5) Group dicarboxylic acid unit as an essential component, and may have an oxycarboxylic acid unit described later.

—O—R ³ —O— (3)
[In the formula (3), R ³ represents a divalent chain aliphatic hydrocarbon group and / or a divalent alicyclic hydrocarbon group, and is not limited to one type when copolymerized. ]
^-OC-R 4 -CO- (4)
[In the formula (4), R ⁴ represents a direct bond or a divalent chain aliphatic hydrocarbon group and / or a divalent alicyclic hydrocarbon group. It is not limited to species. ]
—OC—R ⁵ —CO— (5)
[In Formula (5), R ⁵ represents a divalent aromatic hydrocarbon group, and is not limited to one type when copolymerized. ]

  The diol component giving the diol unit of the formula (3) is usually one having 2 to 10 carbon atoms, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexane. Examples include dimethanol. Among these, a diol having 2 to 4 carbon atoms is preferable, ethylene glycol or 1,4-butanediol is more preferable, and 1,4-butanediol is particularly preferable.

  The dicarboxylic acid component that gives the dicarboxylic acid unit of the formula (4) usually has 2 to 10 carbon atoms, and examples thereof include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid. Among these, succinic acid or adipic acid is preferable.

  Examples of the aromatic dicarboxylic acid component that gives the aromatic dicarboxylic acid unit of the formula (5) include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and the like, among which terephthalic acid and isophthalic acid are preferable, and terephthalic acid is particularly preferable. preferable. Moreover, aromatic dicarboxylic acid in which a part of the aromatic ring is substituted with a sulfonate is exemplified. Two or more types of aliphatic dicarboxylic acid components, aliphatic diol components, and aromatic dicarboxylic acid components can be used.

  The aromatic aliphatic polyester resin (B) in the present invention may contain an aliphatic oxycarboxylic acid unit. Specific examples of the aliphatic oxycarboxylic acid that gives an aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3, Examples include 3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, or a mixture thereof. Furthermore, these lower alkyl esters or intramolecular esters may be used. When optical isomers exist in these, any of D-form, L-form and racemic form may be sufficient, and a form may be any of solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid is preferable. These aliphatic oxycarboxylic acids can be used alone or as a mixture of two or more.

  The amount of the aliphatic oxycarboxylic acid is such that the lower limit is usually 0 mol% or more, preferably 0.01 mol% or more, and the upper limit is normal among all the components constituting the aromatic aliphatic polyester resin (B). 30 mol% or less, preferably 20 mol% or less.

  The aromatic aliphatic polyester resin (B) can be produced by the same production method as the aliphatic polyester resin (A).

  When the melt flow rate (MFR) of the aromatic aliphatic polyester resin (B) used in the present invention is measured at 190 ° C. and 2.16 kg, the lower limit is usually 0.1 g / 10 min or more, and the upper limit is Usually, it is 100 g / 10 min or less, preferably 50 g / 10 min or less, particularly preferably 30 g / 10 min or less.

<Content ratio>
Regarding the content, when the mass part of the aliphatic polyester resin (A) is represented by (A) and the mass part of the aromatic aliphatic polyester resin (B) is represented by (B), (A) / [(( A) + (B)] = 0.30-0.95. A preferred range is 0.50 to 0.90, a more preferred range is 0.40 to 0.90, and a particularly preferred range is 0.60 to 0.80. If the content ratio of the aliphatic polyester resin (A) is too small, the biodegradability may be inferior or the moldability of the film may be reduced. On the other hand, the content ratio of the aliphatic polyester resin (A) is If the amount is too large, the tensile elongation may be insufficient or the tear strength may be reduced. The aliphatic polyester resin (A) and the aromatic aliphatic polyester resin (B) may be used alone or in combination of two or more.

  The content of the above-mentioned aromatic aliphatic polyester resin (B) is preferably 1% by mass or more and 70% by mass or less based on the entire resin composition (100% by mass). The lower limit of the content is more preferably 5% by mass or more, and still more preferably 10% by mass or more. Most preferably, it is 20 mass% or more. The upper limit of the content is more preferably 50% by mass or less, and still more preferably 40% by mass. If the content of the aromatic aliphatic polyester resin (B) is too large, the stiffness of the film is insufficient, and it may be necessary to increase the thickness of the film for use as various packaging materials. On the other hand, if the content of the aromatic aliphatic polyester resin is too small, the tensile elongation rate, tear strength, etc. may be insufficient.

<Starch (C)>
“Starch (C)” in the present invention refers to a natural polymer in which a large number of α-glucose molecules are polymerized by glycosidic bonds and a modified product thereof, which is a carbohydrate (polysaccharide) having a molecular formula (C ₆ H ₁₀ O ₅ ) _n. . “Modification” includes all modification methods such as chemical, physical and biological. As chemical modification, some or all of the structural units of the carbohydrate (polysaccharide) are modified by chemical reaction such as esterification, etherification, oxidation, reduction, coupling, dehydration, hydrolysis, dehydrogenation, halogenation, etc. In particular, it indicates that the hydroxyl group is etherified or esterified. Physical modification means changing physical properties such as changing the crystallinity. Biological degeneration refers to changing a chemical structure or the like using a living organism.

  Specific examples of the starch (C) used in the present invention include corn starch, waxy corn starch, high amylose corn starch, wheat starch, rice starch, potato starch, sweet potato starch, tapioca starch, pea starch and the like. Corn starch, potato starch Starch and the like are preferred, and corn starch is most preferred.

  Content of the starch (C) in a resin composition represents the mass part of an aliphatic polyester-type resin (A) by (A), and the mass part of an aromatic aliphatic polyester-type resin (B) is (B). When the mass part of the starch (C) is represented by (C), it is (C) / [(A) + (B)] = 0.05 to 0.50. A preferable range of the mass ratio is 0.10 to 0.45. The lower limit of the mass ratio is more preferably 0.20. The upper limit is more preferably 0.40, and particularly preferably 0.30. If the content of starch (C) is too small, the effect of improving physical properties by starch (C) may not be sufficiently exhibited. If the content of starch (C) is too large, water resistance, hydrolysis resistance, flexibility The nature etc. may be impaired. The starch (C) may be used alone or in combination of two or more.

  When the resin composition of the present invention is formed into a film having a thickness of 30 μm by a method such as inflation molding, the tensile elastic modulus in the direction parallel to the resin flow is preferably 200 MPa or more. In this case, the lower limit of the tensile modulus is more preferably 230 MPa, particularly preferably 250 MPa, still more preferably 280 MPa, and most preferably 300 MPa. The tensile modulus is usually 500 MPa or less, and the upper limit of the tensile modulus is preferably 450 MPa, more preferably 450 MPa, still more preferably 430 MPa, and most preferably 400 MPa. When the tensile elastic modulus is lower than 200 MPa, when used as a packaging material such as a shopping bag or a garbage bag, if the weight of the content is large, it may not be able to withstand the weight of the content. On the other hand, if the elastic modulus is greater than 500 MPa, the flexibility of the film is impaired and the usability may deteriorate.

  When the resin composition of the present invention is formed into a film having a thickness of 30 μm, the Elmendorf tear strength in the flow parallel direction of the resin is preferably 5 N / mm or more, more preferably 10 N / mm or more. Preferably it is 15 N / mm or more, More preferably, it is 20 N / mm. If the Elmendorf tear strength is less than 5 N / mm, there may be practical problems when used as shopping bags, compost bags, garbage bags, and the like.

  When the resin composition of the present invention is formed into a film having a thickness of 30 μm, it is preferable that the weight loss in the horticultural soil is 10% or more in 8 days in an environment of 50 ° C. A more preferable weight loss rate is 15% or more, and most preferably 20% or more. If the weight loss rate is less than 10% in 8 days, the film remains in the soil for a long time when discarded, and is not environmentally preferable, and a film with a low initial weight loss rate may not be completely biodegraded. Therefore, it is not preferable.

<Polyhydric alcohol (D)>
The resin composition of the present invention contains a polyhydric alcohol (D). The polyhydric alcohol (D) is an organic compound having two or more hydroxyl groups. Specifically, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,8-octanediol, 1,9 -Nanondiol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, glycerin, glycerin monoalkyl ester, glycerin dialkyl ester, glycerin monoalkyl ether, glycerin dialkyl ether. Preferred examples include ethylene glycol, diethylene glycol, glycerin, glycerin monoester, and the like, and particularly preferred is glycerin.

  The content of the polyhydric alcohol (D) in the resin composition represents (A) the mass part of the aliphatic polyester resin (A), and (B) the mass part of the aromatic aliphatic polyester resin (B). When the mass part of the polyhydric alcohol (D) is represented by (D), (D) / [(A) + (B) + (C)] = 0.0001 to 0.05. Preferably it is 0.0005-0.04, More preferably, it is 0.001-0.03, Most preferably, it is 0.002-0.02. If the polyhydric alcohol (D) is too small, the starch and resin may not be mixed well and the smoothness of the film may be lost. On the other hand, if the polyhydric alcohol (D) is too large, the viscosity of the resin will decrease, making it difficult to mold. The polyhydric alcohol may bleed out from the surface of the surface.

<Compatibilizer>
The resin composition of the present invention may contain a compatibilizing agent. The compatibilizing agent is an additive that improves the compatibility when the incompatible dissimilar resin or the starch and the resin are mixed. By adding a compatibilizing agent, the compatibility can be improved.

  In general, the compatibilizer is preferably added in an amount of 0.01% by mass or more and 10% by mass or less based on the entire resin composition (100% by mass). The lower limit of the addition amount is more preferably 0.1% by mass or more, and further preferably 1% by mass or more. The upper limit of the addition amount is more preferably 5% by mass or less, further preferably 3% by mass or less, and particularly preferably 2% by mass or less.

  Examples of the compatibilizer include a polymer compatibilizer, a low molecular organic compound, an inorganic compound, an organic-inorganic composite, etc., but the polymer compatibilizer and the low molecular organic compound are molded products. From the viewpoint of physical properties, a polymer type compatibilizer is more preferable from the viewpoint of the molding process. Further, the compatibilizer is preferably one having an acid anhydride group, glycidyl group or ether group structure, and a polymer type compatibilizer having any one of these structures is more preferred. By using a compatibilizing agent having these structures, the effect of improving the compatibility is increased.

  Polymeric compatibilizers include polyester, polyolefin, polyamide, polyether, polycarbonate, acrylic, styrene, urethane, polyacetal, olefin elastomer, unsaturated aliphatic elastomer, hydrogenated Examples thereof include resins such as unsaturated aliphatic elastomers, and two or more kinds of these blocks, grafts or random copolymers. A polar group may be introduced into the molecule by further adding an unsaturated fatty acid anhydride to these copolymers. Maleic anhydride is preferably used as the unsaturated fatty acid anhydride to be added.

  Among these, polyester-based, polyolefin-based, polyamide-based, polyether-based, acrylic-based, styrene-based, olefin-based elastomers, unsaturated aliphatic elastomers, hydrogenated unsaturated aliphatic elastomers, and co-polymerization of two or more of these More preferred are coalesced and the like, and polyolefin-based, polyamide-based, polyether-based, acrylic-based, styrene-based, hydrogenated unsaturated aliphatic elastomers, and copolymers of two or more of these are more preferable.

  As a polyester-based compatibilizing agent, a polyester block containing a structure such as an aromatic polyester such as polyethylene terephthalate or polybutylene terephthalate, polylactic acid, polycaprolactone, or poly-3-hydroxybutyrate as a part of the molecular structure or random or Examples include graft copolymers

  Examples of the polyamide-based compatibilizer include 6 nylon, 6, 6 nylon, and 12 nylon. Examples of the polyether-based compatibilizer include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

  Examples of the styrene type include polystyrene, poly p-methyl styrene, poly α-methyl styrene and the like. Examples of the olefin elastomer include ethylene propylene random copolymer and poly 1-butene. Examples of the unsaturated aliphatic elastomer include polybutadiene, polyisoprene, SBS, and SIS. Examples of the hydrogenated unsaturated aliphatic elastomer include SEBS and SEPS. Among polyolefin-based, polyamide-based, polyether-based, acrylic-based, styrene-based, hydrogenated unsaturated aliphatic elastomers and two or more types of these copolymers, polyolefin / glycidyl acrylate copolymers, Examples include polyolefin / glycidyl methacrylate copolymer, polyolefin / polyether copolymer, polyether ester amide, SEBS, maleic anhydride-modified SEBS, and the like.

<Inorganic filler>
You may mix | blend an inorganic filler with the resin composition of this invention. Examples of such inorganic fillers include silica, mica, talc, titanium oxide, calcium carbonate, diatomaceous earth, allophane, bentonite, potassium titanate, zeolite, sepiolite, smectite, kaolin, kaolinite, glass, limestone, carbon, wollastonite. , Calcined perlite, "silicates such as calcium silicate and sodium silicate", hydroxides such as aluminum oxide, magnesium carbonate, calcium hydroxide, ferric carbonate, zinc oxide, iron oxide, aluminum phosphate, barium sulfate, etc. Can be mentioned. These may be used alone or in combination of two or more.

  The amount of the inorganic filler contained in the resin composition of the present invention is not particularly limited, but the inorganic filler is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the resin composition, and 3 parts by mass. The content is more preferably 20 parts by mass or less and particularly preferably 5 parts by mass or more and 15 parts by mass or less. If the amount of the inorganic filler is too small, the effect of improving the mechanical properties may be reduced. On the other hand, if the amount is too large, the moldability and impact resistance may be deteriorated.

<Organic filler>
Examples of the organic filler include pulp, chitin / chitosan, coconut shell powder, bamboo powder, bark powder, kenaf, and cocoon powder. These may be used alone or in combination of two or more. The content of the organic filler in the resin composition is preferably 60 parts by mass or less with respect to 100 parts by mass of the resin composition.

<Various additives>
Furthermore, conventionally well-known various additives can be mix | blended with the resin composition of this invention. Examples of additives include crystal nucleating agents, antioxidants, anti-blocking agents, ultraviolet absorbers, light-resistant agents, plasticizers, heat stabilizers, colorants, flame retardants, mold release agents, antistatic agents, and antifogging agents. , Surface wettability improvers, incineration aids, pigments, lubricants, dispersion aids, various surfactants, slip agents, hydrolysis inhibitors and the like. These may be used alone or in combination of two or more. Among these, it is particularly preferable to add a slip agent and an antiblocking agent.

  The antifogging agent may be previously kneaded into the resin, or may be applied to the surface of the molded product after molding. Specifically, the antifogging agent used is preferably an ester surfactant of a saturated or unsaturated aliphatic carboxylic acid having 4 to 20 carbon atoms and a polyhydric alcohol. Examples of the slip agent include unsaturated fatty acid amides and unsaturated fatty acid bisamides composed of unsaturated fatty acids having 6 to 30 carbon atoms, most preferably erucic acid amide.

  Examples of the anti-blocking agent include saturated fatty acid amides having 6 to 30 carbon atoms, saturated fatty acid bisamides, methylol amides, ethanol amides, natural silicas, synthetic silicas, synthetic celite, talc and the like.

  Specific examples of the light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, Bis (1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2- (3,5-di-t-butyl-4-hydroxyphenyl) -2-n-butyl-bis (2,2,6,6-tetramethyl-4-piperidyl) malonate, 2- (3,5-di-tert-butyl-4-hydroxyphenyl) -2-n-butyl-bis (1,2,2 , 6,6-pentamethyl-4-piperidyl) malonate, 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl-bis (2,2,6,6-tetramethyl) -4-piperidyl) malonate, 2- 3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl-bis (1,2,2,6,6-pentamethyl-4-piperidyl) malonate, tetrakis (2,2,6, 6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4 Butanetetracarboxylate, mixed (2,2,6,6-tetramethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, mixed (1,2,2,6, 6-pentamethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, mixed {2,2,6,6-tetramethyl-4-piperidyl / β, β, β ′, β '− Tetramethyl-3,9- [2,4,8,10-tetraoxaspiro [5.5] undecane] diethyl} -1,2,3,4-butanetetracarboxylate, mixed {1,2,2 , 6,6-pentamethyl-4-piperidyl / β, β, β ′, β′-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro [5.5] undecane] diethyl}- 1,2,3,4-butanetetracarboxylate, 1,2-bis (3-oxo-2,2,6,6-tetramethyl-4-piperidyl) ethane, 1- (3,5-di-t -Butyl-4-hydroxyphenyl) -1,1-bis (2,2,6,6-tetramethyl-4-piperidyloxycarbonyl) pentane, poly [1-oxyethylene (2,2,6,6-tetra Methyl-1,4-piperidyl) oxys Sinyl], poly [2- (1,1,4-trimethylbutylimino) -4,6-triazinediyl- (2,2,6,6-tetra and -4-piperidyl) iminohexamethylene- (2,2 , 6,6-tetramethyl-4-piperidyl) imino], N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (2,2,6,6- Tetramethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate and its N-methyl compound, succinic acid and 1- (2-hydroxyethyl) -4-hydroxy-2,2, Examples include polycondensates with 6,6-tetramethylpiperidine.

  Among these, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl- Bis (1,2,2,6,6-pentamethyl-4-piperidyl) malonate is particularly preferred.

  As the UV absorber that may be added to the resin composition of the present invention, among the UV absorbers such as benzophenone-based, benzotriazole-based, salicylic acid-based, and cyanoacrylate-based, a benzotriazole-based UV absorber is preferable. Specifically, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (4,6-diphenyl-1,3,5-triazine-2 -Yl) -5-hexyloxy-phenol.

  Examples of the antioxidant that may be added to the resin composition of the present invention include BHT, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), pentaerythritol tetrakis [3- (3,5-dithiol). -Tert-butyl-4-hydroxyphenyl) propionate], 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-α, α ′, α ″-(mesitylene-2,4, 6-triyl) tri-p-cresol, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-tris [(4-tert-butyl-3-hydroxy -2,6-xylyl) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3,5-tris (3,5-di-tert-butyl) -4- Droxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, calcium diethylbis [{3,5-bis (1,1-dimethylethyl) -4-hydroxy Phenyl} methyl] phosphonate, bis (2,2′-dihydroxy-3,3′-di-tert-butyl-5,5′-dimethylphenyl) ethane, N, N′-hexane-1,6-diylbis [3 Hindered phenolic antioxidants such as-(3,5-di-tert-butyl) -4-hydroxyphenyl] propionamide, tridecyl phosphite, diphenyldecyl phosphite, tetrakis (2,4-di-tert- Butylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphonite, bis [2,4-bis (1,1-dimethylethyl) -6 Phosphorous antioxidants such as methylphenyl] ethyl ester phosphorous acid, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, 3-hydroxy-5,7-di-tert-butyl-furan Examples include lactone-based antioxidants such as reactive organisms of -2-one and xylene, sulfur-based antioxidants such as dilauryl thiodipropionate and distearyl thiodipropionate, and mixtures of two or more thereof. Of these, hindered phenol antioxidants are preferably used.

  Preferable hindered phenol antioxidants include Irganox 3790, Irganox 1330, Irganox 1010, Irganox 1076, Irganox 3114, Irganox 1425WL, Irganox 1098, Irganox HP2225FL, Irganox HP2341, Irgaphos XP- 30 (above, manufactured by Ciba Specialty Chemicals Co., Ltd.) and Sumilyzer BBM-S (manufactured by Sumitomo Chemical Co., Ltd.) are used. The most preferred antioxidant is Irganox 3790 (1,3,5-tris [(4-tert-butyl-3-hydroxy-2,6-xylyl) methyl] -1,3,5-triazine-2,4, 6 (1H, 3H, 5H) -trione), Irganox 1330 (3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-α, α ′, α ″-(mesitylene-2) , 4,6-triyl) tri-p-cresol).

  The addition amount of these additives is usually 0.001% by mass or more and 10% by mass or less based on the whole resin composition (100% by mass). The lower limit of the addition amount is preferably 0.01% by mass or more, more preferably 0.1% by mass or more. The upper limit of the addition amount is preferably 5% by mass or less, more preferably 3% by mass or less. Moreover, the resin composition of this invention can also mix | blend a freshness keeping agent, an antibacterial agent, etc. as a functional additive.

  Examples of the terminal blocking agent include carbodiimide compounds, epoxy compounds, oxazoline compounds, etc. Among them, carbodiimide compounds are preferably used.

<Carbodiimide compound>
In the present invention, a carbodiimide compound can be suitably used mainly for the purpose of suppressing hydrolysis due to moisture in the atmosphere. The carbodiimide compound used is a compound (including a polycarbodiimide compound) having one or more carbodiimide groups in the molecule, and such a carbodiimide compound uses, for example, an organophosphorus compound or an organometallic compound as a catalyst, It can be synthesized by subjecting an isocyanate compound to a decarboxylation condensation reaction in a solvent-free or inert solvent at a temperature of 70 ° C. or higher.

Among the above carbodiimide compounds, the monocarbodiimide compounds include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, and di-β-naphthylcarbodiimide. Etc. can be illustrated. Of these, dicyclohexylcarbodiimide and diisopropylcarbodiimide are preferred because they are easily available industrially.
Examples of the polycarbodiimide compound include U.S. Pat. No. 2,941,956, Japanese Patent Publication No. 47-33279, J. Pat. Org. Chem. 28, p2069-2075 (1963), and Chemical Review 1981, 81, No. 4, p. 619-p. What was manufactured by the method described in 621 grade | etc., Can be used.

  In the present invention, a polycarbodiimide compound may be used. The lower limit of the degree of polymerization is 2 or more, preferably 4 or more, and the upper limit is usually 40 or less, preferably 20 or less. When the degree of polymerization is too large, dispersibility in the composition becomes insufficient, and for example, it may cause poor appearance in an inflation film.

  The carbodiimide compound may be added during the preparation of the resin composition described later, or kneaded into one or two types of polyesters among the aliphatic polyester resin (A) and the aromatic aliphatic polyester resin (B). You may mix and shape | mold with all the components of a resin composition by carrying out dry blending with another component at the time of shaping | molding. Alternatively, an aliphatic polyester-based resin (A) and / or an aromatic aliphatic polyester-based resin (B) is used to prepare a master batch of a high concentration carbodiimide compound, and aliphatic so that the carbodiimide compound has a predetermined concentration during molding. The polyester resin (A) and / or the aromatic aliphatic polyester resin (B) and starch (C) may be dry blended and diluted.

<Other ingredients>
In the resin composition of the present invention, biodegradable resins and natural products, such as polylactic acid, polycaprolactone, polyamide, polyvinyl alcohol, cellulose ester, cellulose, paper, wood flour, Fine powders of animal / plant substances such as chitin / chitosan, coconut shell powder, walnut shell powder, or a mixture thereof can be blended.

<Kneading method>
In the present invention, all conventionally known mixing / kneading techniques can be applied. As the mixer, a horizontal cylindrical type, V-shaped, double-cone type mixer, a blender such as a ribbon blender or a super mixer, various continuous mixers, or the like can be used. Moreover, as a kneading machine, a batch type kneading machine such as a roll or an internal mixer, a one-stage type, a two-stage type continuous kneading machine, a twin screw extruder, a single screw extruder, or the like can be used.

  Although the preparation method of the resin composition of this invention is not specifically limited, The method of melt-mixing the blended raw material chip | tip with the same extruder, the method of mixing after melt | dissolving with each separate extruder, etc. are mentioned. In addition, it is possible to obtain the molded body at the same time as adjusting the resin composition by supplying each raw material chip directly to the molding machine. A method of adding and blending various additives, inorganic fillers, organic fillers, the above-mentioned “other components”, other polyesters, etc. when the components are mixed and heated and melted. At this time, blending oil or the like can also be used for the purpose of uniformly dispersing the various additives.

  The mixing order of each component for preparing the resin composition of the present invention is that, after mixing the aromatic aliphatic polyester resin (B) and starch (C), the aliphatic polyester resin (A) is further mixed therewith. It is preferable to make it. The above-mentioned method can be used as the kneading method, but the aromatic aliphatic polyester resin (B) and starch (C) are mixed into a batch type kneader such as a roll or an internal mixer, a one-stage type, a two-stage type continuous kneader, Aliphatic polyester resin (A) may be mixed with the pellets obtained by melt-kneading with a twin screw extruder, a single screw extruder or the like and kneaded again. Moreover, you may contact and mix the pellet which mixed the aromatic aliphatic polyester-type resin (B) and starch (C), and shape | mold an aliphatic polyester-type resin (A).

  Further, after mixing the aliphatic aliphatic polyester resin (B) and starch (C), the aliphatic polyester resin (A) may be mixed. When the aliphatic polyester resin (A) is mixed, the aromatic polyester resin (A) is mixed. The aliphatic polyester resin (B) may be mixed at the same time. Moreover, aliphatic polyester resin (A), aromatic aliphatic polyester resin (B) and starch (C) may be used alone or in combination of two or more.

  When the aliphatic polyester resin (A) and the starch (C) are first kneaded and then the aromatic aliphatic polyester resin (B) is mixed to prepare a resin composition, it may be difficult to form a uniform film. . Moreover, when the aliphatic polyester resin (A), the aromatic aliphatic polyester resin (B) and the starch (C) are simultaneously added and mixed and kneaded to prepare a resin composition, the effect of the present invention is not achieved. There is a case.

  What is necessary is just to mix so that the mixing ratio in each step at the time of preparing the resin composition of this invention may become the content mass ratio of the above-mentioned resin composition finally, but prepares the resin composition of this invention. In order to do this, after mixing the aromatic aliphatic polyester resin (B) and starch (C) at a mass ratio of (B) / (C) = 10/90 to 95/5, the aliphatic polyester resin Mixing (A) at a mass ratio of (A) / [(A) + (B) + (C) + (D)] = 0.05 to 0.95 sufficiently achieves the effect of the present invention. Preferred for obtaining. The mixing of the aromatic aliphatic polyester resin (B) and starch (C) in the previous stage is more preferably (B) / (C) = 20/80 to 90/10, and 30/70 to 80 / in mass ratio. 20 is particularly preferable, and 35/65 to 70/30 is more preferable. The mixing ratio of the aliphatic polyester resin (A) in the latter stage is (A) / [(A) + (B) + (C) + (D)] = 0.10 to 0.90 in mass ratio. Is more preferable, 0.15 to 0.85 is particularly preferable, and 0.20 to 0.80 is still more preferable.

  Although the mixing time of the said polyhydric alcohol (D) is not specifically limited, It is preferable to mix when mixing an aromatic aliphatic polyester-type resin (B) and starch (C). The polyhydric alcohol (D) is preferably mixed at (D) / [(A) + (B) + (C)] = 0.0001 to 0.05 to prepare a resin composition. (D) / [(A) + (B) + (C)] is more preferably 0.0005 to 0.04, particularly preferably 0.001 to 0.03, and still more preferably 0. 0.002-0.02.

<Molding method>
The resin composition of the present invention can be molded by various molding methods applied to general-purpose plastics. Examples of the molding method include compression molding (compression molding, laminate molding, stampable molding), injection molding, extrusion molding, and coextrusion molding (film molding by inflation method and T-die method, laminate molding, pipe molding, electric wire / cable molding. , Profile molding), hollow molding (various blow molding), calendar molding, foam molding (melt foam molding, solid phase foam molding), solid molding (uniaxial stretching molding, biaxial stretching molding, roll rolling molding, stretch oriented nonwoven fabric Examples include molding, thermoforming (vacuum forming, pressure forming), plastic working, powder forming (rotary forming), various non-woven fabric forming (dry method, adhesion method, entanglement method, spunbond method, etc.), among others, extrusion forming, Injection molding, foam molding or hollow molding is preferably applied, and the specific shape is preferably applied to a film, a container or a fiber.

  Also, these molded products are provided with chemical functions, electrical functions, magnetic functions, mechanical functions, friction / wear / lubricating functions, optical functions, thermal functions, surface functions such as biocompatibility, etc. For this purpose, it is also possible to perform various purposeful secondary processing. Examples of secondary processing include embossing, painting, adhesion, printing, metalizing (plating, etc.), machining, surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, Coating) and the like.

<Application>
The resin composition of the present invention is excellent in moldability, and is excellent in surface characteristics and mechanical characteristics of a molded body formed from the resin composition. For this reason, the molded body made of the resin composition of the present invention has a wide range of uses such as packaging materials, agricultural materials, and building materials for packaging various foods, medicines, miscellaneous liquids, powders, and solids. Is preferably used. Specific applications include injection molded products (for example, fresh food trays, fast food containers, outdoor leisure products, etc.), extruded products (films, for example, fishing lines, fishing nets, vegetation nets, water retaining sheets, etc.), hollow Examples include molded products (bottles, etc.). In addition, other agricultural films, coating materials, fertilizer coating materials, laminate films, plates, stretched sheets, monofilaments, non-woven fabrics, flat yarns, staples, crimped fibers, striped tapes, split yarns, composite fibers, blow bottles, Foam, shopping bag, garbage bag, compost bag, cosmetic container, detergent container, bleach container, rope, binding material, hygiene cover stock material, cold box, cushion material film, multifilament, synthetic paper, surgery for medical use Examples thereof include DDS such as thread, suture, artificial bone, artificial skin, and microcapsule, and wound dressing.

  In addition, information electronic materials such as toner binders and thermal transfer ink binders, automotive interior parts such as electrical product casings, instrument panels, sheets and pillars, and automotive exterior structural materials such as bumpers, front grills and wheel covers. Can be used. Among them, more preferably, packaging materials such as packaging films, bags, trays, bottles, cushioning foams, fish boxes, and the like, and agricultural materials such as mulching films, tunnel films, house films, sun covers, etc. , Herbicidal sheets, cocoon sheets, germination sheets, vegetation mats, nursery beds, flower pots and the like. The resin composition of the present invention can be excellent in tear strength, moldability, lightness, biodegradability, etc., and has a high elastic modulus and can hardly be wrinkled. It is particularly preferred to be used.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist. In the examples, “part” means “part by mass”.

<Measurement method of tear strength>
The Elmendorf tear strength was measured according to JIS K7128. “Tear strength” in the present invention indicates Elmendorf tear strength of “MD” (direction parallel to the resin flow during molding) and “TD” (direction perpendicular to the resin flow during molding).

<Measurement method of yield strength, breaking strength, tensile breaking elongation>
It measured by the tension test based on JISK6781. The “tensile elongation at break” in the present invention is the tensile elongation at break in “MD” and “TD”.

<Impact strength>
Using a punch impact tester manufactured by Toyo Seiki Co., Ltd., using a film with a width of 110 mm and a length of 1300 mm as a sample, punching 12 holes of 50 mm in diameter with a semispherical arm with a tip of 25 mm in diameter, It was measured.

<Measurement method of tensile modulus>
Based on JIS K7127, the tensile elastic modulus was measured with Shimadzu Corporation precision universal testing machine Autograph AG-2000. The “tensile elastic modulus” in the present invention is a tensile elastic modulus in “MD”.

<Measurement method of MFR>
The melt flow rate (MFR) was measured at 190 ° C. and a 2.16 kg load.

<Test method for biodegradability>
A film with a thickness of 30 μm formed by inflation is cut into a 7 cm x 3 cm rectangle, embedded in the soil of a polyethylene tapper container filled with soil, the lid is closed, and constant temperature and humidity at 50 ° C and humidity of 90% It was left to stand for a certain period in the tank. The change in weight before and after standing was measured.

Examples 1 to 8 and Comparative Example 2
As an aromatic aliphatic polyester resin (B), 40 parts of PBAT resin (manufactured by BASF, Ecoflex (registered trademark)), as starch (C), 60 parts of corn starch (manufactured by Nippon Corn Starch, corn starch Y-3P), As the polyhydric alcohol (D), 1 part of glycerin was kneaded at 120 ° C. by an extruder to obtain “PBAT / starch mixed pellets”.

  Next, as an aliphatic polyester-based resin (A), a PBS-based resin (manufactured by Mitsubishi Chemical Corporation, AZ91TN) and / or a PBSA-based resin (manufactured by Mitsubishi Chemical Corporation, AD92WN), an aromatic aliphatic polyester-based resin (B) , PBAT resin (manufactured by BASF, Ecoflex (registered trademark)) and the above-mentioned “PBAT / starch mixed pellets” were kneaded at 180 ° C. by an extruder at the ratios shown in Tables 1 and 2. PBAT was kneaded so that the amount of “PBAT / starch mixed pellet” was insufficient and the ratio shown in Table 1 and Table 2 was added.

  The kneaded pellets were dried at 70 ° C. under nitrogen flow for 10 hours. A film having a blow ratio of 2.5, a folding diameter of 300 mm, a molding temperature of 160 ° C., and a thickness of 30 μm was molded from the pellets with an inflation molding machine (Empura Sangyo Co., Ltd., model E30SP). In Examples 1 to 8, the surface properties of the films were good, and no wrinkles were observed during molding. Mechanical properties and biodegradability tests of the obtained film were performed, and the results are shown in Tables 1 and 2.

Comparative Example 1
As the aliphatic polyester resin (A), PBS resin (AZ91TN manufactured by Mitsubishi Chemical Corporation), and as the aromatic aliphatic polyester resin (B), PBAT resin (Ecoflex (registered trademark) manufactured by BASF) is shown in Table 1. The mixture was kneaded at 180 ° C. with an extruder at the ratio shown in FIG. The kneaded pellets were dried at 70 ° C. under nitrogen flow for 10 hours. A film was formed from the pellets at 160 ° C. using an inflation molding machine. Although the surface of the film had no irregularities, it was a film that was prone to wrinkles. The obtained film was subjected to mechanical properties and biodegradability tests, and the results are shown in Table 1.

Example 9
In parts by mass shown in Table 1, as an aliphatic polyester resin (A), a PBSA resin (AD92WN manufactured by Mitsubishi Chemical Corporation), and as starch (C), corn starch (corn starch Y-3P manufactured by Nippon Corn Starch), As a monohydric alcohol (D), 1 part of glycerin was kneaded at 120 ° C. by an extruder to obtain “PBSA / starch mixed pellets”.

  Next, as the aromatic aliphatic polyester resin (B), a PBAT resin (Ecoflex (registered trademark) manufactured by BASF) and the above-mentioned “PBSA / starch mixed pellets” were used at a ratio shown in Table 2 by an extruder. Kneading was performed at 180 ° C. The kneaded pellets were dried at 70 ° C. under nitrogen flow for 10 hours. A film having a blow ratio of 2.5, a fold diameter of 300 mm, a molding temperature of 160 ° C., and a thickness of 30 μm was molded from the pellets using an inflation molding machine (Model E30SP, manufactured by Engineering Plastics Co., Ltd.). Mechanical properties and biodegradability tests of the obtained film were performed, and the results are shown in Table 2.

  As shown in Tables 1 and 2, the film made of the resin composition of the present invention was excellent in mechanical properties such as improved tear strength, high tensile elastic modulus, and resistance to wrinkles. It was also excellent in biodegradability.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, the present invention can be changed as appropriate without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and a resin composition accompanying such a change, and a film made of the resin composition are also included in the present invention. It should be understood as encompassed within the technical scope.

  The resin composition of the present invention is excellent in moldability, and the film formed from the resin composition is excellent in tear strength, film rigidity, biodegradability, etc. It can be widely used as packaging materials for packaging powders and solids, agricultural materials, building materials, various waste treatment materials, and the like.

Claims (8)

  Including an aliphatic polyester resin (A) having an aliphatic dicarboxylic acid and an aliphatic diol as main components, an aromatic aliphatic polyester resin (B), starch (C) and a polyhydric alcohol (D), in a mass ratio , (A) / [(A) + (B)] = 0.30-0.95, (C) / [(A) + (B)] = 0.05-0.50, (D) / [ (A) + (B) + (C)] = 0.0001 to 0.05.   The resin composition according to claim 1, wherein the starch (C) is corn starch.   The resin composition according to claim 1 or 2, wherein the aliphatic polyester resin (A) is a polybutylene succinate resin and / or a polybutylene succinate adipate resin.   A method for producing a resin composition comprising mixing an aliphatic polyester resin (A) after mixing an aromatic aliphatic polyester resin (B) and starch (C).   After mixing the aliphatic aliphatic polyester resin (B) and starch (C) in a mass ratio of (B) / (C) = 10/90 to 95/5, the aliphatic polyester resin (A) is mixed. The method for producing a resin composition according to claim 4, wherein mixing is performed at a mass ratio of (A) / [(A) + (B) + (C) + (D)] = 0.05 to 0.95.   Furthermore, polyhydric alcohol (D) is mixed by (D) / [(A) + (B) + (C)] = 0.0001-0.05 The resin composition of Claim 4 or Claim 5 mixed. Manufacturing method.   A resin composition produced by using the method for producing a resin composition according to any one of claims 4 to 6.   A film comprising the resin composition according to claim 1 as a main component.