JP6874294B2 - A polyester resin composition, a film formed by molding the resin composition, and a bag formed by molding the film. - Google Patents

Description

The present invention relates to a resin composition containing an aliphatic polyester resin, which can provide a film having excellent mechanical properties.

Conventionally, paper, plastic films, metal foils, etc. have been used in a wide range of applications such as liquids and powders for various foods, chemicals, miscellaneous goods, packaging materials for solids, agricultural materials, building materials, etc. .. In particular, plastic films are excellent in strength, water resistance, moldability, transparency, cost, etc., and are used in many applications as bags and containers. As a typical plastic film, for example, there is one made of polyethylene, polypropylene, polystyrene, polyvinyl chloride and the like. However, these resins are difficult to decompose in a natural environment, and have problems such as generating harmful gas when incineration is performed and damaging the incinerator.

Various resins are being researched to solve the above problems. For example, aliphatic polyester resins such as polybutylene succinate and polybutylene succinate adipate, aliphatic oxycarboxylic acid resins such as polylactic acid, and aromatic aliphatic copolymer polyesters such as polybutylene adipate terephthalate. A technique for solving the above problem by using a resin is known (see, for example, Patent Document 1).

Further, it has been known that aromatic aliphatic copolymerized polyester resins such as polybutylene adipate terephthalate improve biodegradability by allowing aliphatic units to be present between aromatic units, but they are molded into a film. In this case, as a resin composition having excellent tear strength while maintaining high impact strength, an aliphatic polyester resin containing a predetermined amount of succinic acid-derived structural units and an aromatic having a low content of aromatic dicarboxylic acid components. An aliphatic polyester resin composition containing an aliphatic copolymerized polyester resin and an aliphatic oxycarboxylic acid resin in a predetermined ratio is disclosed (see, for example, Patent Document 2).

Special Table 2001-500907 Japanese Unexamined Patent Publication No. 2013-040321

Aliphatic polyester resins such as polybutylene succinate and polybutylene succinate adipate have a high crystallization rate and good moldability, but the tear strength of the film after molding may be insufficient. It was. In the technique described in Patent Document 2, polylactic acid is set to a specific ratio in the total dicarboxylic acid unit in the aliphatic polyester resin such as polybutylene succinate and polybutylene succinate adipate. An aliphatic oxycarboxylic acid resin such as Polybutylene adipate terephthalate and an aromatic aliphatic copolymer polyester resin such as polybutylene adipate terephthalate are contained in a predetermined ratio to improve the tear strength. Was weak, and there was a case where the film became a so-called stiff film.

An object of the present invention is to provide a resin composition having excellent tensile strength and also excellent tear strength when molded into a film, and a film or bag obtained by molding the resin composition.

As a result of diligent research to solve the above problems, the present inventor has determined that the succinic acid unit in the total dicarboxylic acid unit is a specific ratio of polyester resin (A), polyester resin (B) and polyester resin (C). In addition, it has been found that by containing a specific cellulose ester (D), it is possible to obtain a film having excellent tensile strength and improved tear strength.

That is, the gist of the present invention is the following [1] to [ 5].
[1] An aliphatic polyester resin containing an aliphatic diol unit and an aliphatic dicarboxylic acid unit, which is a polyester resin (A) containing 87 mol% or more of a succinic acid unit in the total aliphatic dicarboxylic acid unit. An aromatic aliphatic copolymerized polyester resin containing a group diol unit, an aliphatic dicarboxylic acid unit, and an aromatic dicarboxylic acid unit, wherein the aromatic dicarboxylic acid unit is 5 mol% or more and 95 mol% or more in the total dicarboxylic acid unit. One or more cellulose esters (D) selected from the group consisting of the polyester resin (B) contained below, the polyester resin (C) containing an aliphatic oxycarboxylic acid, and the group consisting of cellulose triacetate, cellulose acetate propionate and cellulose acetate butyrate. ), And the content ratio of the compound (D) is 5% by weight or more .
[ 2 ] The resin composition according to [1], wherein the cellulose ester (D) is cellulose acetate propionate.
[ 3 ] A film obtained by molding the resin composition according to [1] or [2].
[ 4 ] A mulch film obtained by molding the resin composition according to [1] or [2].
[ 5 ] A bag obtained by molding the film according to [3].

According to the present invention, it is possible to provide a resin composition having excellent moldability and excellent tensile strength and also excellent tear strength when formed into a film.
For example, when the resin composition according to the present invention is formed into a film and then molded into a bag, the tear strength is excellent and the bag can be prevented from tearing. In addition, the excellent tensile strength makes it possible to prevent the bag from tearing. Further, the mulch film obtained by molding the resin composition according to the present invention also has excellent tear strength and can be preferably used.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.
The polyester resin composition of the present invention contains the following polyester resins (A) to (C) and a cellulose ester (D). The polyester resin (A) is an aliphatic polyester resin containing an aliphatic diol unit and an aliphatic dicarboxylic acid unit, and is a polyester containing 87 mol% or more of succinic acid-derived units among all aliphatic dicarboxylic acid-derived units. It is a resin. The polyester resin (B) is an aromatic aliphatic copolymerized polyester resin containing an aliphatic diol unit, an aliphatic dicarboxylic acid unit, and an aromatic dicarboxylic acid unit, and among all dicarboxylic acid-derived units, aromatic dicarboxylic acid. It is a polyester resin containing 5 mol% or more and 95 mol% or less of an acid unit. The polyester resin (C) is a polyester resin containing an aliphatic oxycarboxylic acid. Further, the polyester resin composition of the present invention contains one or more cellulose esters (D) selected from the group consisting of cellulose triacetate, cellulose acetate propionate and cellulose acetate butyrate.

In the present invention, the aliphatic diol refers to an aliphatic hydrocarbon group in which two hydroxyl groups are bonded, and as the aliphatic hydrocarbon group, a linear aliphatic hydrocarbon group is usually used, but it has a branched structure. It may have an annular structure, or may have a plurality of them. The aliphatic dicarboxylic acid unit refers to an aliphatic hydrocarbon group in which two carboxyl groups are bonded to each other. As the aliphatic hydrocarbon group, a linear aliphatic hydrocarbon group is usually used, but it has a branched structure. It may have an annular structure, and it may have a plurality of them.

Further, the polyester resin according to the present invention is a polymer having a repeating unit, and each repeating unit is also referred to as a compound unit for a compound from which each repeating unit is derived. Specifically, for example, a repeating unit derived from an aliphatic diol is an "aliphatic diol unit", a repeating unit derived from an aliphatic dicarboxylic acid is a "aliphatic dicarboxylic acid unit", and a repeating unit derived from an aromatic dicarboxylic acid is used. An "aromatic dicarboxylic acid unit" and a repeating unit derived from an aliphatic oxycarboxylic acid are also referred to as an "aliphatic oxycarboxylic acid unit".

1. 1. Polyester resin composition The resin composition of the present invention is a resin composition containing a polyester resin (A), a polyester resin (B), a polyester resin (C) and a cellulose ester (D).
When molded into a film using the polyester resin composition of the present invention, it is possible to make the film excellent in moldability, tensile strength and tear strength.

Further, since it is possible to make these physical properties more excellent, the content ratio of the polyester resin (A) is preferably 5% by weight or more, more preferably 10% by weight or more, and particularly preferably. Is 15% by weight or more. Further, for the same reason, the content ratio of the polyester resin (B) is preferably 5% by weight or more, more preferably 10% by weight or more, and particularly preferably 15% by weight or more. For the same reason, the content ratio of the polyester resin (C) is preferably 1% by weight or more, more preferably 3% by weight or more, and particularly preferably 5% by weight or more. The content ratio of the compound (D) is preferably 0.1% by weight or more, more preferably 1% by weight or more, and particularly preferably 5% by weight or more.

Further, when a film is molded using the resin composition according to the present invention, the tear strength of the film and the impact strength of the film can be further improved. Therefore, the polyester resin (A) and the polyester resin The polyester resin (C) is preferably contained in an amount of 1 to 20% by weight, more preferably 3 to 15% by weight, and particularly preferably 5 to 10% by weight based on the total of (B) and the polyester resin (C). To do.
The polyester resin composition of the present invention may contain various compounds other than the polyester resin (A), the polyester resin (B), the polyester resin (C) and the cellulose ester (D). These other components will be described later.

1.1. Polyester resin (A)
The polyester resin (A) used in the present invention is an aliphatic polyester resin containing an aliphatic diol unit and an aliphatic dicarboxylic acid unit, and 87 mol% of the total aliphatic dicarboxylic acid-derived unit contains a succinic acid-derived unit. Contains the above. The polyester resin (A) may be a mixture of polyester resins having different amounts of succinic acid units. For example, an aliphatic polyester resin containing no dicarboxylic acid structural unit other than that derived from succinic acid and an aliphatic polyester resin other than those derived from succinic acid. It is also possible to blend with an aliphatic polyester resin containing a structural unit and adjust the amount of the structural unit derived from succinic acid in the polyester resin (A) within the above predetermined range for use.

More specifically, the polyester resin (A) is a polyester resin containing an aliphatic diol unit represented by the following formula (1) and an aliphatic dicarboxylic acid unit represented by the following formula (2).
-O-R ^1- O- (1)
-OC-R ^2- CO- (2)
In formula (1), R ¹ represents a divalent aliphatic hydrocarbon group. When the polyester resin (A) is a copolymer, the polyester resin (A) may contain two or more kinds of aliphatic diol units represented by the formula (1). In the above formula (2), R ² represents a divalent aliphatic hydrocarbon group. The aliphatic diol unit and the aliphatic dicarboxylic acid unit represented by the above formulas (1) and (2) may be derived from a compound derived from petroleum or a compound derived from a plant material. Although not, it is desirable to include compounds derived from plant materials. When the polyester resin (A) is a copolymer, the polyester resin (A) may contain two or more kinds of aliphatic dicarboxylic acid units represented by the formula (2). The aliphatic dicarboxylic acid unit represented by the formula (2) contains 87 mol% or more of the structural unit derived from succinic acid with respect to the total aliphatic dicarboxylic acid unit. By setting the amount of the structural unit derived from succinic acid in the polyester resin (A) within a predetermined range, it is possible to obtain a film having a high elastic modulus having excellent tensile strength. For the same reason, the structural unit derived from succinic acid is preferably contained in an amount of 87 mol% or more, more preferably 90 mol% or more, still more preferably 93 mol% or more, based on the total aliphatic dicarboxylic acid unit. ..

The aliphatic diol giving the diol unit of the formula (1) is not particularly limited, but from the viewpoint of moldability and mechanical strength, an aliphatic diol having 2 or more and 10 or less carbon atoms is preferable, and 4 or more and 6 or less carbon atoms are preferable. Aliphatic diols are particularly preferred. For example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like can be mentioned, and 1,4-butanediol is particularly preferable. It should be noted that two or more kinds of the above aliphatic diols can be used respectively.

The dicarboxylic acid component that gives the dicarboxylic acid unit of the formula (2) is not particularly limited, but an aliphatic dicarboxylic acid having 2 or more and 40 or less carbon atoms is preferable, and an aliphatic dicarboxylic acid having 4 or more and 10 or less carbon atoms is particularly preferable. preferable. For example, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid and the like can be mentioned. Among them, adipic acid and sebacic acid are preferable, and adipic acid is particularly preferable. It should be noted that two or more kinds of the above dicarboxylic acids can be used respectively.

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

From the viewpoint of moldability, the amount of the aliphatic oxycarboxylic acid unit is preferably 20 mol% or less, more preferably 10 mol% or less, and particularly preferably 10 mol% or less of all the repeating units constituting the polyester resin (A). It is 5 mol% or less.
Further, the polyester resin (A) in the present invention is "trifunctional or higher aliphatic polyhydric alcohol", "trifunctional or higher functional aliphatic polyvalent carboxylic acid or acid anhydride thereof" or "trifunctional or higher functional aliphatic polyhydric acid". The melt viscosity may be increased by copolymerizing the "oxycarboxylic acid", or the chain length may be extended by a coupling agent.

Specific examples of the trifunctional aliphatic polyhydric alcohol include trimethylolpropane and glycerin, and specific examples of the tetrafunctional aliphatic polyhydric alcohol include pentaerythritol and the like. These can 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, and specific examples of the tetrafunctional polyvalent carboxylic acid or its acid anhydride include Cyclopentanetetracarboxylic acid or an acid anhydride thereof and the like can be mentioned. These can be used alone or in combination of two or more.

The trifunctional aliphatic oxycarboxylic acid has (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) having one carboxyl group and two hydroxyl groups. It is divided into types, and any type can be used, but from the viewpoint of moldability, mechanical strength and appearance of the molded product, (i) two carboxyl groups such as malic acid and one hydroxyl group are contained in the same molecule. The type having is preferable, and more specifically, malic acid is preferably used. The tetrafunctional aliphatic oxycarboxylic acid component is (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. It is divided into a type that shares a group in the same molecule and a type that shares three hydroxyl groups and one carboxyl group in the same molecule (iii). Any type can be used, but the carboxyl group can be used. Those having a plurality of them are preferable, and more specific examples thereof include citric acid and tartaric acid. These can be used alone or in combination of two or more.

The amount of structural units derived from such trifunctional or higher functional components is usually 0 mol% or more, preferably 0.01 mol% or more, with the total structural units constituting the polyester resin (A) being 100 mol%. The upper limit is usually 5 mol% or less, preferably 2.5 mol% or less.
Examples of the coupling agent include diisocyanate, oxazoline, diepoxy compound, acid anhydride and the like, and specific examples thereof include 2,4-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate and hydrogen. Examples thereof include xylylene diisocyanate and hexamethylene diisocyanate. The amount of these additions is 0.1 to 5 parts by weight with respect to 100 parts by weight of the polyester resin (A).

The polyester resin (A) requires a structural unit derived from succinic acid, and further has a structural unit derived from the dicarboxylic acid component other than succinic acid and a structural unit derived from the diol component, and has a structure derived from the polyhydric alcohol component. It optionally has a unit, a structural unit derived from the polyvalent carboxylic acid component, a structural unit derived from an aliphatic oxycarboxylic acid component, or a coupling agent.
The polyester resin (A) used in the present invention can be produced by a known method. For example, a general method of melt polymerization such as performing an esterification reaction and / or an ester exchange reaction between the above-mentioned aliphatic dicarboxylic acid containing succinic acid and an aliphatic diol and then performing a polycondensation reaction under reduced pressure. Although it can be produced by a known solution heating dehydration condensation method using an organic solvent, a method of producing by melt polymerization performed without a solvent is preferable from the viewpoint of economy and simplification of the production process.

The average molecular weight of the polyester resin (A) can be measured by gel permeation chromatography (GPC), and the weight average molecular weight using polystyrene as a standard substance is usually 10,000 or more and 1,000,000 or less. However, since it is advantageous in terms of moldability and mechanical strength, it is preferably 20,000 or more and 500,000 or less, and more preferably 50,000 or more and 400,000 or less.

The melt flow rate (MFR) of the polyester resin (A) is usually 0.1 g / 10 minutes or more and usually 100 g / 10 minutes or less when measured at 190 ° C. and 2.16 kg. From the viewpoint of moldability and mechanical strength, it is preferably 50 g / 10 minutes or less, particularly preferably 30 g /
It is less than 10 minutes.
The melting point of the polyester resin (A) is preferably 70 ° C. or higher, more preferably 75 ° C. or higher, preferably 170 ° C. or lower, further preferably 119 ° C. or lower, and particularly preferably less than 100 ° C. When there are a plurality of melting points, it is preferable that at least one melting point is within the above range. The elastic modulus is preferably 180 to 500 MPa. When the melting point is out of the range, the moldability is inferior, when the elastic modulus is 180 MPa or less, problems are likely to occur in the moldability and the bag making property, and when the elastic modulus is 500 MPa or more, the effect of improving the tear strength and the impact strength is difficult to obtain. The method for adjusting the melting point and elastic modulus of the polyester resin (A) is not particularly limited, but for example, the type of copolymerization component other than succinic acid can be selected, the copolymerization ratio of each can be adjusted, and the like. It can be adjusted by combining them.

1.2. Polyester resin (B)
The polyester resin (B) used in the present invention is an aromatic aliphatic copolymerized polyester resin containing an aliphatic diol unit, an aliphatic dicarboxylic acid unit, and an aromatic dicarboxylic acid unit. Specifically, for example, an aliphatic diole unit represented by the following formula (3), an aliphatic dicarboxylic acid unit represented by the following formula (4), and an aromatic represented by the following formula (5). Those containing an aromatic aliphatic copolymerized polyester composed of a group dicarboxylic acid unit as a main component are preferable, and those having biodegradability are preferable.

-O-R ³ -O- (3)
In formula (3), R ³ represents a divalent aliphatic hydrocarbon group. If the polyester resin (B) is a copolymer, it may contain two or more R ³ in the polyester resin (B).
-OC-R ^4- CO- (4)
In formula (4), R ⁴ represents a divalent aliphatic hydrocarbon group. If the polyester resin (B) is a copolymer, it may contain two or more R ⁴ in the polyester resin (B).

-OC-R ^5- CO- (5)
In formula (5), R ⁵ represents a divalent aromatic hydrocarbon group. If the polyester resin (B) is a copolymer, it may contain two or more R ⁵ in the polyester resin (B).
The diol giving the diol unit of the formula (3) is not particularly limited, but a diol having 2 or more and 10 or less carbon atoms is preferable from the viewpoint of the balance between cost and mechanical strength. For example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like can be mentioned. Among them, a diol having 2 or more and 4 or less carbon atoms is preferable, ethylene glycol and 1,4-butanediol are more preferable, and 1,4-butanediol is particularly preferable.

The dicarboxylic acid giving the dicarboxylic acid unit of the formula (4) is not particularly limited, but is preferably one having 2 or more and 12 or less carbon atoms in view of the balance between cost and biodegradability. For example, succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like can be mentioned. Of these, sebacic acid or adipic acid is preferable.
The aromatic dicarboxylic acids that give the aromatic dicarboxylic acid units of the formula (5), it is preferred that the ring structure of R ⁵ is 2 or less, and more specifically, for example, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, etc. . Among them, it is preferable from the viewpoint of biodegradability R ⁵ is a phenylene group, and more specifically, for example terephthalic acid, are preferred isophthalic acid, terephthalic acid is particularly preferred. Further, it may be an aromatic dicarboxylic acid in which a part of the aromatic ring is replaced with a sulfonate.

It should be noted that two or more kinds of aliphatic dicarboxylic acids, aliphatic diols, and aromatic dicarboxylic acids can be used.
The polyester resin (B) may have an aliphatic oxycarboxylic acid unit. Specific examples of the aliphatic oxycarboxylic acid giving the aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 2-hydroxy-3, Examples thereof include 3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, or a mixture thereof. Further, these lower alkyl esters or intramolecular esters may be used. When optical isomers are present in these, any of D-form, L-form, and racemic form may be used, and the form may be solid, liquid, or aqueous solution. Of these, lactic acid or glycolic acid is preferred. These aliphatic oxycarboxylic acids can be used alone or as a mixture of two or more kinds.

The amount of the aliphatic oxycarboxylic acid is preferably 20 mol% or less, more preferably 10 mol% or less, among all the constituent components constituting the polyester resin (B).
Further, the polyester resin (B) is the same as the polyester resin (A), "trifunctional or higher aliphatic polyhydric alcohol", "trifunctional or higher functional aliphatic polyvalent carboxylic acid or its acid anhydride" or "trifunctional". The melt viscosity may be increased by copolymerizing the above aliphatic polyvalent oxycarboxylic acid, and the chain length is extended by a coupling agent such as a diisocyanate or a diepoxy compound. You may.

The content of the aromatic dicarboxylic acid unit in the polyester resin (B) is preferably from the viewpoint of melting point and biodegradability with respect to the total (100 mol%) of the aliphatic dicarboxylic acid unit and the aromatic dicarboxylic acid unit. It is 5 mol% or more, more preferably 35 mol% or more, particularly preferably 40 mol% or more, preferably 95 mol% or less, more preferably 65 mol% or less, and particularly preferably 60 mol% or less.

The polyester resin (B) can be produced by a known production method in the same manner as the polyester resin (A).
The average molecular weight of the polyester resin (B) can be measured by gel permeation chromatography (GPC), and the weight average molecular weight using polystyrene as a standard substance is usually 5,000 or more and 1,000,000 or less. However, it is preferably 10,000 or more and 500,000 or less because it is advantageous in terms of moldability and mechanical strength.

The melt flow rate (MFR) of the polyester resin (B) used in the present invention is usually 0.1 g / 10 minutes or more at the lower limit and 100 g / 10 minutes at the upper limit when measured at 190 ° C. and 2.16 kg. It is preferably less than or equal to, more preferably 50 g / 10 minutes or less, and particularly preferably 30 g / 10 minutes or less. The melt flow rate (MFR) of the polyester resin (B) can be adjusted by the molecular weight.

The melting point of the polyester resin (B) is preferably 70 ° C. or higher, more preferably 75 ° C. or higher, preferably 205 ° C. or lower, still more preferably 180 ° C. or lower, and particularly preferably 140 ° C. or lower. When the melting point is 70 ° C. or lower, the moldability and heat resistance of the composition are inferior, and when the melting point is 205 ° C. or higher, the melting point difference from other components becomes large and the moldability is inferior. The melting point of the polyester resin (B) can be adjusted by the amount of aromatic dicarboxylic acid or the amount of oxycarboxylic acid.

1.3. Polyester resin (C)
The polyester resin (C) used in the present invention contains a polyester resin composed of an aliphatic oxycarboxylic acid unit as a main component.
Examples of the aliphatic oxycarboxylic acid giving the aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, and 5-hydroxy. Ester acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 3-hydroxyhexanoic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, etc. Alternatively, these lower alkyl esters or intramolecular esters can be mentioned. When optical isomers are present in these, any of D-form, L-form or racemic form may be used, and the form may be solid, liquid or aqueous solution. Of these, particularly preferred are lactic acid or glycolic acid, with lactic acid being the most preferred. These aliphatic oxycarboxylic acids can be used alone or as a mixture of two or more kinds.

Further, the polyester resin (C) may have an aliphatic oxycarboxylic acid unit derived from a trifunctional or higher functional aliphatic oxycarboxylic acid component. The trifunctional aliphatic oxycarboxylic acid component is (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxyl group and two hydroxyl groups. Any type can be used, but from the viewpoint of reducing coloring and foreign matter of the polyester resin (C) and improving the quality, there are two (i) carboxyl groups such as malic acid and a hydroxyl group. A type having one of them in the same molecule is preferable, and more specifically, malic acid or the like is preferably used. The tetrafunctional aliphatic oxycarboxylic acid component is (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. It is divided into a type in which a group is shared in the same molecule and a type in which (iii) three hydroxyl groups and one carboxyl group are shared in the same molecule, and any type can be used. Specific examples thereof include citric acid and tartaric acid. These can be used alone or in combination of two or more.

The polyester resin (C) may contain other structural units derived from the above-mentioned aliphatic polyesters and aromatic aliphatic polyesters. The content of the other structural units in the polyester resin (C) is such that the total of the structural units derived from the aliphatic oxycarboxylic acid and the other structural units is 100 mol%, and the lower limit is usually 0 mol% or more, preferably 0 mol% or more. It is 0.01 mol% or more, and the upper limit is usually 5 mol% or less, preferably 2.5 mol% or less.

The polyester resin (C) can be obtained by a method of directly dehydrating and polycondensing the above raw materials, a method of ring-opening polymerization of cyclic dimers of lactic acid and hydroxycarboxylic acids, production by microorganisms, and the like.
The melt flow rate (MFR) of the polyester resin (C) used in the present invention is usually 0.1 g / 10 minutes or more at the lower limit and 100 g / 10 minutes at the upper limit when measured at 190 ° C. and 2.16 kg. Hereinafter, it is preferably 50 g / 10 minutes or less, and particularly preferably 30 g / 10 minutes or less.

1.4. Cellulose ester (D)
The resin composition of the present invention contains a cellulose ester (D).
The cellulose ester (D) of the resin composition of the present invention is one or more selected from the group consisting of triacetyl cellulose (TAC), cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB). .. Of these, cellulose acetate propionate (CAP) is preferred.

The cellulose ester (D) may contain 5 to 40 parts by mass of a plasticizer with respect to 100 parts by mass of the cellulose ester from the viewpoint of improving the fluidity and increasing the mechanical strength of the molded product.
As the plasticizer, an adipate-based plasticizer excluding the phthalate ester and a polyester-based plasticizer are preferable.
The number average molecular weight of the cellulose ester (D) is preferably in the range of 10,000 to 100,000, more preferably in the range of 15,000 to 80,000, from the viewpoint of maintaining fluidity (processability).

The number average molecular weight can be measured by gel permeation chromatography (GPC).
The melting range of the cellulose ester (D) is preferably 120 ° C. or higher, more preferably 130 ° C. or higher, preferably 250 ° C. or lower, still more preferably 240 ° C. or lower, and particularly preferably less than 230 ° C.

Specific examples of the cellulose ester (D) include CAP-480-20, CAP-482-0.5, CAP-504-0.2, CAB-551-0.01, CAB-551-0.2, and CAB-553 manufactured by Eastman. -0.4, CAB-531-1, CAB-500-5, CAB-381-0.1, CAB-381-0.1, CAB-381-0.5, CAB-381-2, CAB-381-20, CAB-381-20 BP, CAB-321-0.1, CAB-171-15, etc. are mentioned, and among them, CAP-480-20, CAP-482-0.5
, CAP-504-0.2 is preferred.

The resin composition of the present invention is characterized by containing the polyester resin (A), the polyester resin (B), the polyester resin (C) and the cellulose ester (D). As a result, in addition to the tensile strength when the resin composition is molded into a film, the tear strength is dramatically improved. The reason is that the cellulose ester (D) is compatible with the polyester resin (A) and also functions as a compatibilizer with the polyester resin (B) and the polyester resin (C). It is presumed that the interfacial interaction between them was improved. In the resin composition of the present invention, the content of the cellulose ester (D) with respect to the total of the polyester resin (A) and the cellulose ester (D) is compatible with the resin (A), and the resin (A) From the viewpoint of softening and improving the interaction with other resins, 1 to 60% by weight is preferable, and 3 to 50% by weight is more preferable.

1.5. Other Ingredients The resin composition according to the present invention includes lubricants, fillers (fillers), plasticizers, antistatic agents, antioxidants, light stabilizers, ultraviolet absorbers, dyes, pigments, antioxidants, etc. Various additives, synthetic resins such as polycaprolactone, polyamide, polyvinyl alcohol, starch, paper, wood powder, chitin / chitosanaceous material, coconut shell powder, walnut shell powder and other fine powders of animal / plant substances, or mixtures thereof. May be included as "other ingredients". These can be arbitrarily used as long as the effects of the present invention are not impaired. One of these may be used alone, or two or more thereof may be mixed and used. Since the amount of these additives added usually does not impair the physical properties of the biodegradable resin composition, the total amount of the substances to be mixed is 0.01% by weight or more with respect to the total amount of the biodegradable resin composition 40. It is preferably% by weight or less.

1.5.1. Lubricants For example, when a lubricant is included in the resin composition according to the present invention, it is possible to improve the moldability when the resin composition is made into a film and then molded into a bag. In addition, the mouth of the bag can be easily opened, and the usability of the bag can be improved. Further, if the mouth of the bag is easily opened, the inspection at the time of manufacturing the bag becomes easy.

As the lubricant, known ones can be used without particular limitation. Specifically, paraffin oil, paraffin such as solid paraffin, higher fatty acid such as stearic acid and palmitic acid, higher alcohol such as palmityl alcohol and stearyl alcohol, calcium stearate, zinc stearate, barium stearate, aluminum stearate, Metal salts of fatty acids such as magnesium stearate and sodium palmitate, fatty acid esters such as butyl stearate, glycerin monostearate, and diethylene glycol monostearate, stearoamide, methylene bisstearoamide, ethylene bisstearoamide, and oxystearic acid. Examples thereof include fatty acid amides such as ethylenediamide, methylolamide, oleylamide, stearic acid amide and erucic acid amide, and waxes such as carnauba wax and montan wax. As the lubricants and waxes, one type may be used alone, or two or more types may be used in any ratio and combination. Of these, erucic acid amide is particularly preferable. These lubricants are usually in the range of 0.01 to 2% by weight, preferably 0.05 to 0.5% by weight in the resin composition.

1.5.2. Filler When the resin composition according to the present invention contains a filler, it can contribute to stabilization during film molding by improving the fluidity and crystallization rate of the resin composition, and to reducing the eccentricity of film mechanical properties. it can. Further, when the resin composition is used as a film, blocking between the films can be prevented. Alternatively, when the film is molded into a bag, the mouth of the bag can be easily opened. Further, the film or bag can be colored to improve the light-shielding property and the light reflectivity.

The filler may be fibrous, powder-granular, plate-shaped or needle-shaped depending on its shape, and powder-granular or plate-shaped filler is particularly preferable. Examples of the powdery and granular filler include mineral particles such as talc, zeolite, silica soil, kaolin, clay, silica, and quartz powder, metal carbonate particles such as calcium carbonate, magnesium carbonate, and heavy calcium carbonate, calcium silicate, aluminum silicate, and silicic acid. Metal silicate particles such as magnesium, metal oxide particles such as alumina, silica, zinc oxide and titanium oxide, metal hydroxide particles such as aluminum hydroxide, calcium hydroxide and magnesium hydroxide, barium sulfate, calcium sulfate and the like. Examples thereof include metal sulfate particles and carbon particles such as carbon black. Further, as the plate-shaped filler, mica can be mentioned. From the viewpoint of making it easier to open the mouth of the bag and preventing blocking, it is preferable to use talc, calcium carbonate, or silica, and from the viewpoint of coloring the film or bag and improving the light-shielding property or light reflectivity. , Carbon black or titanium oxide should be used. The dispersed state of the filler in the molded product such as a film or the resin composition is 0.08 to 25 μm in number average particle size, more preferably 0.1 μm to 5 μm. If it deviates from this range, the effect of adding the above filler becomes low. One type of filler may be used alone, or two or more types may be mixed and used. These fillers are usually used in the resin composition in the range of 0.05 to 40% by weight.

The hardness of the filler used is not particularly limited, but if the hardness is too low, the physical properties such as rigidity and heat resistance tend to be low, and if it is too high, the appearance tends to be poor and the physical properties of the film strength tend to be deteriorated. Therefore, it is preferable that the hardness is not too high or too low. The hardness (Mohs hardness) of the filler used is preferably an upper limit of 9 or less and a lower limit of 1 or more, more preferably an upper limit of 8 or less and a lower limit of 2 or more, and particularly preferably an upper limit of 7 or less and a lower limit. Is 3 or more. The Mohs hardness referred to here is a value obtained by rubbing a standard substance with a sample substance and measuring the hardness based on the presence or absence of scratches. The standard substances are as follows. Hardness 1) talc, hardness 2) gypsum, hardness 3) square stone, hardness 4) fluorite, hardness 5) phosphorus ash stone, hardness 6) regular long stone, hardness 7) crystal, hardness 8) yellow ball, hardness 9) corundum (steel ball) ), Hardness 10) Diamond. More specifically, talc, calcium carbonate, silica, titanium oxide, barium sulfate and the like can be used as the filler. For example, as the talc, LMS100, LMR100, PKP80, PKP53S manufactured by Fuji Tarku Kogyo can be used. Can be mentioned. Examples of calcium carbonate include NITOREX30P, NITOREX23P, NS # 100, NCC series NITOREX30PS, NCC # 2310, NCC # 1010, NCC-V2300, NCC-V1000 manufactured by Nitto Calcium, and Wiskal A manufactured by Maruo Calcium. Be done. Examples of the silica particles include Aerosil 200 manufactured by Japan Aerosil Co., Ltd., Aerosil 300 and the like. As the titanium oxide, CR-60, CR-80, and CR-68 manufactured by Ishihara Sangyo Co., Ltd. can be used.

1.5.3. Plasticizer If the resin composition has poor flowability, it is advisable to add a plasticizer. In particular, when the resin composition contains a filler, the viscosity of the resin composition may increase and the flowability of the resin composition may deteriorate, which can be improved by adding a plasticizer to the resin composition. be able to.
As the plasticizer, known ones can be used without particular limitation. For example, methyl adipate, diethyl adipate, diisopropyl adipate, di-n-propyl adipate, di-2-ethylhexyl adipate, diisobutyl adipate, dibutyl adipate, diisodecyl adipate, dibutyl diglycol adipate, di-2-ethylhexyl azelate, dibutyl sebacate. , Di-2-ethylhexyl sebacate, fatty acid esters such as methyl acetyl silicate, glycerin esters such as triacetin, diethyl maleate, dibutyl maleate, dioctyl maleate, dibutyl fumarate, dioctyl fumarate and the like maleic acid and fumaric acid. Esters, adipic acid-1,3-butylene glycol, polyester epoxidized esters such as epoxidized soybean oil, trimellitic acid esters such as trioctyl remeritate, triethylene glycol diacetate, tributyl acetylcitrate, glycerin diacetone Propionate, glycerin diacet monocaprelate, glycerin diacet monocaplate, glycerin diacet monolaurate, glycerin diacet monooleate, glycerin monoacet monobehenate, acetylated monoglyceride such as glycerin monoacet monostearate, diglycerin acetate, Examples thereof include polyglycerin fatty acid esters such as decaglycerin propionate, tetraglycerin caprilate, decaglycerin laurate, decaglycerin oleate, and decaglycerin behenate, and rosin derivatives. These plasticizers are usually used in the resin composition in the range of 0.05 to 10% by weight.

1.5.4. Antistatic agent Further, when the antistatic agent is contained in the resin composition according to the present invention, the moldability when the resin composition is formed into a film and then molded into a bag can be improved. In addition, the film and resin can be easily handled. Any antistatic agent can be used as long as the effects of the present invention are not significantly impaired. As a specific example, surfactant-type nonionic, cationic, and anionic surfactants are preferable.

Nonionic antistatic agents include glycerin fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, alkyl diethanolamine, hydroxyalkyl monoethanolamine, polyoxyethylene alkyl amine, polyoxyethylene alkyl amine fatty acid ester alkyl diethanol. Examples include amides. Of these, alkyldiethanolamines and the like are preferable.

Examples of the cationic antistatic agent include tetraalkylammonium salts and trialkylbenzylammonium salts. Examples of the anionic antistatic agent include alkyl sulfonates, alkylbenzene sulfonates, and alkyl phosphates. Of these, alkylbenzene sulfonate is preferable. This is because it has good kneadability with resin and has a high antistatic effect.

The amount of the antistatic agent used is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.5% by weight or more, preferably 1% by weight or more, and usually 5% by weight, based on the biodegradable resin composition. By weight or less, preferably 3% by weight or less. If it exceeds the above range, the surface of the biodegradable resin composition becomes sticky, and the product value tends to decrease. Further, when it falls below the above range, the antistatic property improving effect tends to decrease.

1.5.5. Other additive starches include cornstarch, waxy cornstarch, high amylose cornstarch, wheat starch, rice starch, potato starch, sweet potato starch, tapioca starch, pea starch, etc., which are unmodified and modified. Both can be used. Modification includes all methods of modification such as chemical, physical, and biological, and chemical modification includes esterification, etherification, oxidation, and reduction of some or all of the constituent units of carbohydrates (polysaccharides). It shows that it is modified by a chemical reaction such as coupling, dehydration, hydrolysis, dehydrogenation, and halogenation, and in particular, it shows that the hydroxyl group is etherified and esterified. In addition, physical modification indicates that the physical properties are changed, such as changing the degree of crystallinity. In addition, biological denaturation indicates that the chemical structure and the like are changed by using an organism.

As the light-resistant agent, bis decanoate (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester, reaction product of 1,1-dimethylethylhydroperoxide and octane, bis ( 1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butylmalonate, bis (1,2,2) , 6,6-pentamethyl-4-piperidyl) sebacate, methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate , 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydride) Toxiphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, poly [[6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4 -Diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] and other hindered amine-based stabilizers And so on. The light-resistant agent is preferably used in combination with an ultraviolet absorber, and a combination of a hindered amine-based stabilizer and an ultraviolet absorber is effective.

The amount of the light resistant agent to be mixed is usually 100 ppm or more, preferably 200 ppm or more, based on the weight of the biodegradable resin composition, and is usually 5 parts by weight or less, preferably 1 part by weight or less, more preferably. It is 0.5 parts by weight or less. Below this range, the effect of the lightfastener tends to decrease. Further, if it exceeds this range, the manufacturing cost tends to be high, the heat resistance of the biodegradable resin composition tends to be inferior, and the bleed-out of the light-resistant agent tends to occur.

Examples of the ultraviolet absorber include 2- (2H-benzotriazole-2-yl) -4-6-bis (1-methyl-1-phenylethyl) phenol and 2- (4,6-diphenyl-1,3,5). -Triazine-2-yl) -5-[(hexyl) oxy] phenol and the like can be mentioned. As the ultraviolet absorber, it is particularly preferable to use two or more different types of ultraviolet absorbers in combination.

The amount of the ultraviolet absorber to be mixed is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 100 ppm or more, preferably 200 ppm or more, and usually 5 weight by weight, based on the weight of the biodegradable resin composition. % Or less, preferably 2% by weight or less, more preferably 0.5% by weight or less. Below this range, the effectiveness of the UV absorber tends to decrease. On the other hand, if it exceeds this range, the manufacturing cost tends to be too high, the heat resistance of the biodegradable resin composition is inferior, and the bleed-out of the ultraviolet absorber tends to occur.

Examples of the heat stabilizer include dibutylhydroxytoluene (BHT; 2,6-di-t-butyl-4-methylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), pentaerythritol tetrakis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 3,3', 3 ", 5,5', 5" -hexa-tert-butyl-a, a', a " -(Methylylene-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-Hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, calcium diethylbis [[3,5-bis (1,1-dimethylethyl) -4- Hydroxyphenyl] Methyl] phosphonate, bis (2,2'-dihydroxy-3,3'-di-tert-butyl-5,5'-dimethylphenyl) ethane, N, N'-hexane-1,6-diylbis [ Hindered phenolic heat stabilizers such as 3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide; tridecylphosphite, diphenyldecylphosphite, tetrakis (2,4-di-tert-butyl) Phenyl) [1,1-biphenyl] -4,4'-diylbisphosphonite, bis [2,4-bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphite, bis ( 2,4-Di-tert-butylphenyl) Phosphyl-based heat stabilizers such as pentaerythritol difasphite; 3-hydroxy-5,7-di-tert-butyl-furan-2-one-reactive organisms of xylene, etc. Lactone-based heat stabilizers; sulfur-based antioxidants such as dilaurylthiodipropionate and distearylthiodipropionate; and the like.

The amount of the heat stabilizer to be mixed is usually 100 ppm or more, preferably 200 ppm or more, based on the weight of the biodegradable resin composition, and usually 5 parts by weight or less, preferably 1 part by weight or less, more preferably. Is 0.5 parts by weight or less. Below this range, the effect of the heat stabilizer tends to decrease. On the other hand, if it exceeds this range, the manufacturing cost tends to be high, and bleed-out of the heat stabilizer may occur.

Examples of the terminal encapsulant mainly used for the purpose of suppressing hydrolysis due to moisture in the atmosphere include carbodiimide compounds, epoxy compounds, oxazoline compounds, etc. Among the above carbodiimide compounds, the monocarbodiimide compound is Examples thereof include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, and di-β-naphthylcarbodiimide. Among these, dicyclohexylcarbodiimide and diisopropylcarbodiimide are preferable because they are easily available industrially.

Examples of the polycarbodiimide compound include US Pat. No. 2,941956, Japanese Patent Application Laid-Open No. 47-33279, J. Mol. Org. Chem. Vol. 28, p2069-2075 (1963), and Chemical Review 1981, Vol. 81, No. 4, p. Those produced by the method described in 619-621 and the like can be used.
Examples of the organic diisocyanate which is a raw material for producing the polycarbodiimide compound include aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate and a mixture thereof. Specific examples thereof include 1,5-naphthalenediocyanate, 4, 4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylenediisocyanate, 1,4-phenylenediocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4- Mixture of tolylene diisocyanate and 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, methylcyclohexanediisocyanate, tetramethylxyli Examples thereof include range isocyanate, 2,6-diisopropylphenyl isocyanate, 1,3,5-triisopropylbenzene-2,4-diisocyanate and the like.

Examples of the carbodiimidization catalyst used in the decarboxylation condensation reaction of organic diisocyanate include organic phosphorus compounds and organometallic compounds represented by the general formula M (OR) n (where M is titanium,
Metal atoms such as sodium, potassium, vanadium, tungsten, hafnium, zirconium, lead, manganese, nickel, calcium and barium are indicated, and R indicates an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. , N indicates the valence that the metal atom M can take) is preferable. Among them, phosphorene oxides are preferable for organophosphorus compounds, and titanium, hafnium, or zirconium alkoxides are preferable for organometallic compounds because of their high activity.

Specific examples of phosphorene oxides include 3-methyl-1-phenyl-2-phosphorene-1-oxide, 3-methyl-1-ethyl-2-phosphorene-1-oxide, and 1,3-dimethyl-2. -Phosphorene-1-oxide, 1-phenyl-2-phosphorene-1-oxide, 1-ethyl-2-phosphorene-1-oxide, 1-methyl-2-phosphorene-1-oxide and their double bond isomers Can be exemplified. Of these, 3-methyl-1-phenyl-2-phosphorene-1-oxide, which is easily available industrially, is particularly preferable.

When synthesizing these polycarbodiimide compounds, an active hydrogen-containing compound capable of reacting with monoisocyanate or other terminal isocyanate groups can be used to control the degree of polymerization to a desired degree. Compounds used for such purposes include monoisocyanate compounds such as phenylisocyanate, tolylisocyanate, dimethylphenylisocyanate, cyclohexylisocyanate, butylisocyanate, and naphthylisocyanate, methanol, ethanol, phenol, cyclohexanol, N-methylethanolamine, and the like. Hydroxyl group-containing compounds such as polyethylene glycol monomethyl ether and polypropylene glycol monomethyl ether, amino group-containing compounds such as diethylamine, dicyclohexylamine, β-naphthylamine and cyclohexylamine, carboxyl group-containing compounds such as succinic acid, benzoic acid and cyclohexanoic acid, and ethyl mercaptan. , Allyl mercaptan, mercapto group-containing compounds such as thiophenol, and various epoxy group-containing compounds can be exemplified.

One of these carbodiimide compounds may be used alone, or two or more thereof may be mixed and used. In the present invention, it is particularly preferable to use a polycarbodiimide compound, and the degree of polymerization thereof has a lower limit of 2 or more, preferably 4 or more, and an upper limit of usually 40 or less, preferably 20 or less. The amount of these carbodiimides used is usually 0.1 to 5% by weight based on the entire resin composition.

In addition to these, known surface wetting improvers, flame retardants, mold release agents, incineration aids, pigments, dispersion aids, surfactants, hydrolysis inhibitors, end sealants, crystal nucleating agents, compatibilizers, Etc. may be included.
As described above, the resin composition according to the present invention contains the polyester resin (A), the polyester resin (B), the polyester resin (C), and the cellulose ester (D), and the polyester resin (A) is described above. The feature is that the amount of the structural unit derived from succinic acid in the above is within a predetermined range, and the blending ratio of the resins (A) to (C) is within a predetermined range. When a film is molded from a resin composition having such characteristics, the tear strength of the film is improved and the film has excellent impact strength. By molding the film obtained by the resin composition according to the present invention into a bag, it is possible to make a bag that is less likely to be torn by tearing and is less likely to be torn by impact. Alternatively, it is also preferable to use the resin composition according to the present invention as a material for a mulch film for agriculture and the like.

2. Method for Producing Resin Composition As a method for producing the resin composition according to the present invention, a known method can be applied. For example, a method of melting and mixing the blended polyester resin (A), the polyester resin (B), the raw material chips of the polyester resin (C), and the cellulose ester (D) in the same extruder, each of which was melted in a separate extruder. Examples thereof include a method of mixing later. As the extruder, a single-screw or twin-screw extruder can be used. Further, the cellulose ester (D) can be added and blended in the place where the polyester resins (A) to (C) are mixed and melted by heating. At this time, a blending oil or the like can also be used for the purpose of uniformly dispersing other components. On the other hand, it is also possible to directly supply the raw material chips of the polyester resins (A) to (C) to the molding machine to prepare the resin composition and at the same time obtain a molded product such as a film as it is.

3. 3. Film The resin composition according to the present invention can be molded into a film by various molding methods applied to general-purpose plastics. Regarding the molding method, the effect of the present invention is remarkably exhibited, particularly when molding is performed by extrusion molding or inflation molding. More specifically, for example, a method of cooling and solidifying a film-like, sheet-like or cylindrical object extruded to a predetermined thickness from a T-die, I-die, round die or the like with a cooling roll, water, compressed air or the like. Can be mentioned. At this time, it is also possible to obtain a laminated film in which several kinds of compositions are laminated as long as the effects of the present invention are not impaired.

The film-shaped molded product thus obtained may then be subjected to uniaxial or biaxial stretching by a roll method, a tenter method, a tubular method or the like. In the case of stretching, the stretching temperature is usually in the range of 30 ° C. to 110 ° C., and the stretching ratio is in the range of 0.6 to 10 times in each of the vertical and horizontal directions. Further, after stretching, heat treatment may be performed by a method of blowing hot air, a method of irradiating infrared rays, a method of irradiating microwaves, a method of contacting the heat roll, or the like.

4. Mulch film It is even more preferable to mold the resin composition according to the present invention into a mulch film for agriculture and the like. For molding the mulch film, a known method as described above may be used. The multi-film obtained by molding the resin composition according to the present invention has the following effects. It can be said that a mulch film having excellent tear strength is preferably used. In this respect, the mulch film obtained by molding the resin composition according to the present invention has improved tear strength and is also excellent in impact strength. Therefore, in the laid mulch film, it is possible to prevent the film from being torn and the defective portion from becoming large, and it is also possible to prevent the mulch film from being torn due to an impact. Since the resin composition according to the present invention contains components such as an aliphatic polyester, an aromatic aliphatic copolymerized polyester, and an aliphatic oxycarboxylic acid as main components, there is a problem even if the multi-film is used and then embedded in the soil as it is. There is no.

5. Bag The film obtained as described above may be molded into a bag. A known method can be applied to the molding of the bag. For example, it can be molded by heat-sealing the end of an inflation-molded tubular body. Here, as described above, the film constituting the bag has improved tear strength and excellent impact strength. If the film has excellent tear strength, it is possible to prevent vertical tearing of the bag. In addition, the excellent impact strength makes it possible to prevent the bag from tearing when opening the bag or packing an object in the bag.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The following examples are shown for explaining the present invention in detail, and the present invention is not limited to the following examples unless contrary to the gist thereof.
The following resins and compounds were used as the resins and compounds used in the following examples and comparative examples.
<Alphatic polyester resin>
-Polybutylene succinate (hereinafter abbreviated as PBS) "GsPla (registered trademark) FZ91PN" manufactured by Mitsubishi Chemical Corporation
-Polybutylene succinate adipate (hereinafter abbreviated as PBSA) "GsPla (registered trademark) FD92WN" manufactured by Mitsubishi Chemical Corporation
<Aromatic aliphatic copolymerized polyester resin>
-Polybutylene adipate terephthalate (hereinafter abbreviated as PBAT) Ecoflex (registered trademark) manufactured by BASF Corporation * Melting point 120 ° C
<Polyester resin containing aliphatic oxycarboxylic acid>
・ Polylactic acid (hereinafter abbreviated as “PLA”) Ingeo2003D manufactured by Nature Works Japan Co., Ltd.
<Cellulose ester>
-Cellulose acetate propionate (hereinafter abbreviated as "CAP") EAST
MAN CAP-482-20 Acetyl content 2.5%, Propionyl content 46.0%, Hydroxyl content 1.8%, number average molecular weight 75,000
-Cellulose acetate (hereinafter abbreviated as "CA") manufactured by Wako Junyaku Co., Ltd., Acetyl content 38-40%

Production of resin composition [Examples 1 to 3 and Comparative Examples 1 to 3]
PBS, PBSA, PBAT, PLA as resin and CAP or CA as cellulose ester in proportions (parts by weight) shown in Table 1 respectively, twin-screw extruder manufactured by Japan Steel Works, Ltd. (TEX30α-59.5AW-15V, L) / D = 59.5), melt-kneaded using the twin-screw extruder, extruded into a strand shape from the outlet of the extruder, cooled and solidified with water, and then pelletized with a rotary cutter. The obtained pellets were dried at 70 ° C. for 6 hours under nitrogen flow to obtain a resin composition. The set temperature at the time of kneading was 190 ° C., and the screw rotation speed was 200 rpm.

When each resin was charged into the twin-screw extruder, the moisture-proof bag containing each resin was opened and immediately charged into the twin-screw extruder for melt-kneading.
In Table 1, the index of "compoundness" is an index of ease of handling when the resin composition is compounded in each of the Examples and Comparative Examples, and the compoundability "○" is the resin composition. The product was kneaded without any problem, and the compound property "△" means that the strands were not stable or the strands could not be cut with a cutter.

Film molding and evaluation of physical properties [Examples 1 to 3 and Comparative Examples 1 to 3]
Each resin composition obtained in the production of the above resin composition was molded into an inflation molding machine (engineering plastic 30, die diameter: 75 mm, lip width: 0.8 mm) manufactured by Engineering Plastic Industry Co., Ltd. at a molding temperature of 160. A film at ° C., a blow ratio of 3.5, and a thickness of 50 μm was prepared. Further, the moldability (state of bubble and frost) was evaluated according to the following criteria with a discharge rate of 8 kg / h and a constant air blow. The evaluation results of the film containing each resin composition based on the following evaluation criteria are shown in "Inflation moldability" in Table-1.

[Evaluation criteria for film moldability]
◯: Low frost line and good moldability Δ: Frost line is a little high, but there is no problem with moldability ×: Bubbles are not stable and cannot be molded (including foreign matter generation)
[Evaluation of physical properties of film]
The following evaluations were carried out for each of Examples 1 to 3 and Comparative Examples 1 to 3.

<Elastic modulus>
The elastic modulus of the film in the film flow direction (MD) during film molding was measured according to JIS K7127 (1999). The results are shown in the elastic modulus (MD) of Table-1.
<Koshi when made into a film>
In the above elastic modulus evaluation, the elastic modulus of 400 MPa or more was evaluated as ◯, 300 to 400 MPa was evaluated as Δ, and 0 to 300 MPa was evaluated as ×. The results are shown in Table 1 "Koshi when made into a film".

<Elmendorf tear strength>
According to JIS K7128-2 (1998), the tear strength was measured in the film flow direction (MD) during film forming and perpendicular to the film flow direction (TD). The results are shown in "Tear (MD)" and "Tear (TD)" in Table 1, respectively.
<Punching impact strength>
Using a film impact tester manufactured by Toyo Seiki Co., Ltd., the punching impact strength of a film having a diameter of 50 mm was measured according to JIS P8134 (1998). A hemispherical metal jig having a diameter of 25.4 mm was attached to the tip of the punched portion of the impact tester for evaluation. The results are shown in Puncture of Table-1 respectively.

From the results shown in Table-1, it is an aliphatic polyester resin containing an aliphatic diol unit and an aliphatic dicarboxylic acid unit, and contains 87 mol% or more of a succinic acid unit in the total aliphatic dicarboxylic acid unit. An aromatic aliphatic copolymerized polyester resin containing a polyester resin (A), an aliphatic diol unit, an aliphatic dicarboxylic acid unit, and an aromatic dicarboxylic acid unit, wherein the aromatic dicarboxylic acid unit is contained in the total dicarboxylic acid unit. A polyester resin composition containing a polyester resin (B) containing 5 mol% or more and 95 mol% or less, a polyester resin (C) containing an aliphatic oxycarboxylic acid, and a cellulose ester (D) can be used for compounding properties. It has been clarified that a film having excellent inflation moldability and high tear strength and impact strength can be produced.

Claims (5)

An aliphatic polyester resin containing an aliphatic diol unit and an aliphatic dicarboxylic acid unit, which is a polyester resin (A) containing 87 mol% or more of a succinic acid unit in the total aliphatic dicarboxylic acid unit, an aliphatic diol unit. , An aromatic aliphatic copolymerized polyester resin containing an aliphatic dicarboxylic acid unit and an aromatic dicarboxylic acid unit, and among all the dicarboxylic acid units,
Polyester resin (B) containing 5 mol% or more and 95 mol% or less of aromatic dicarboxylic acid units
, A polyester resin (C) containing an aliphatic oxycarboxylic acid, and one or more cellulose esters (D) selected from the group consisting of cellulose triacetate, cellulose acetate propionate and cellulose acetate butyrate, and compound (D). ) Is a polyester resin composition having a content ratio of 5% by weight or more. The resin composition according to claim 1, wherein the cellulose ester (D) is cellulose acetate propionate. A film obtained by molding the resin composition according to claim 1 or 2. A mulch film obtained by molding the resin composition according to claim 1 or 2. A bag obtained by molding the film according to claim 3.