JP6102315B2 - Polyester resin composition and film formed by molding the polyester resin composition - Google Patents

Description

  The present invention relates to a resin composition containing an aliphatic aromatic polyester and a film formed by molding the film. Specifically, the present invention relates to a resin composition containing an aliphatic aromatic polyester that has improved biodegradability and can provide a film excellent in impact resistance, flexibility, thermal decomposition resistance, productivity, and mechanical properties.

  Conventionally, paper, plastic film, metal foil, etc. have been used in a wide range of applications such as liquids and granules for various foods, medicines, miscellaneous goods, packaging materials for solids, agricultural materials, and building materials. . In particular, plastic films are excellent in strength, water resistance, moldability, transparency, cost, etc., and are used in many applications as bags and containers. Typical plastic films include, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate and the like. However, these resins are difficult to decompose in a natural environment, and there are problems such as generation of harmful gases and damage to the incinerator when incineration is performed.

  Therefore, as a means for solving the above-mentioned problems, many studies have been made on biodegradable materials. Typical examples of the biodegradable material include aliphatic polyester resins such as polylactic acid, polybutylene succinate, and polybutylene succinate adipate, and aromatic-aliphatic copolyester resins such as polybutylene adipate terephthalate.

  It is known that aromatic aliphatic copolyester resins such as polybutylene adipate terephthalate improve biodegradability by the presence of aliphatic units between aromatic units. For example, in order to improve the flexibility and tensile strength of an aliphatic polyester resin excellent in crystallinity and moldability, a biodegradable aliphatic-aromatic copolymer polyester (polybutylene adipate terephthalate having a glass transition temperature of 0 ° C. or lower) ) And an aliphatic oxycarboxylic acid resin (polylactic acid), and a film or sheet formed by shaping the polyester resin composition (for example, see Patent Document 1). Also, a composition of an aliphatic aromatic polyester resin (polybutylene succinate terephthalate copolymer) containing an aliphatic dicarboxylic acid unit, an aromatic dicarboxylic acid unit, an aliphatic and / or alicyclic diol unit, and polylactic acid It is disclosed that when both are contained in a specific ratio, the impact resistance of a test piece obtained by injection molding the resin composition is improved. (For example, refer to Patent Document 2).

JP 2003-064245 A JP 2008-031457 A

  However, the composition of an aliphatic aromatic polyester-based resin such as polybutylene adipate terephthalate or polybutylene succinate terephthalate and polylactic acid may have poor inflation moldability or may have reduced impact resistance. . Since polylactic acid has a slow biodegradation rate, it has been studied to extend the life of films and sheets made of a resin composition blended with polylactic acid, but for agricultural purposes such as multifilm and compost bags. In the field of materials, there is a problem that it is inferior in practicality. The biodegradation rate suitable for agricultural materials, moldability and impact resistance were not compatible.

  The present inventors include an aliphatic aromatic polyester (A) having a structural unit derived from an aromatic dicarboxylic acid and a structural unit derived from an aliphatic diol, and a structural unit derived from adipic acid. A polyester resin composition comprising an aliphatic polyester (B) having a structural unit derived from an aliphatic diol and an aliphatic polyester (C) having a structural unit derived from an oxycarboxylic acid as a main component Thus, the present inventors have found that a film suitable for the field of agricultural materials can be obtained because the biodegradability is moderately suppressed and the impact resistance and tear strength are excellent.

That is, the present invention is as follows.
[1] An aliphatic aromatic polyester (A) having a structural unit derived from an aliphatic dicarboxylic acid, a structural unit derived from an aromatic dicarboxylic acid, and a structural unit derived from an aliphatic diol, and a structural unit derived from an aliphatic dicarboxylic acid; A polyester resin composition comprising an aliphatic polyester (B) having a structural unit derived from an aliphatic diol and an aliphatic polyester (C) having a structural unit derived from an oxycarboxylic acid as a main component, A polyester resin composition, wherein the aliphatic aromatic polyester (A) includes a structural unit derived from succinic acid, and the aliphatic polyester (B) includes a structural unit derived from adipic acid.
[2] The polyester resin composition according to [1], wherein the aliphatic polyester (C) is polylactic acid.
[3] The polyester resin composition according to [1] or [2], wherein the aliphatic diol is 1,4-butanediol.
[4] The polyester resin composition according to any one of [1] to [3], wherein the content of the aliphatic polyester (C) is 1% by mass or more and 30% by mass or less.
[5] The polyester resin composition according to any one of [1] to [4], wherein the aliphatic polyester (B) further has a structural unit derived from succinic acid.
[6] The polyester resin composition according to any one of [1] to [5], further containing a slip agent.
[7] The polyester resin composition according to any one of [1] to [6], further containing talc.
[8] The polyester resin composition according to any one of [1] to [7], further containing carbodiimide.
[9] A film formed by molding the polyester resin composition according to any one of [1] to [8].

ADVANTAGE OF THE INVENTION According to this invention, when a moldability is favorable and it is set as a film, it can provide the resin composition which has moderate biodegradability, and is excellent also in tear strength and impact strength.
For example, fast biodegradability may be a problem from the viewpoint of durability, and slow biodegradability may be a problem from the viewpoint of waste treatment, but the polyester resin composition of the present invention According to this, the polyester resin composition can be adjusted to have an “appropriate biodegradation rate” for the use, which is neither early nor late. Further, the polyester resin composition of the present invention exhibits good inflation moldability, and when the polyester resin composition is blown to form a film, it has excellent tear strength and impact strength, and is particularly suitable for use as an agricultural multi-film. be able to.

  Hereinafter, embodiments of the polyester resin composition of the present invention and a film formed by molding the resin composition will be described in detail, but the description of the constituent requirements described below is an example of the embodiment of the present invention. Yes, these are not specific.

  In the following description, an aliphatic diol refers to an aliphatic hydrocarbon group in which two hydroxyl groups are bonded. As the aliphatic hydrocarbon group, a straight chain aliphatic hydrocarbon group is usually used. It may have a structure, may have a ring structure, or may have a plurality of them. The aliphatic dicarboxylic acid refers to an aliphatic hydrocarbon group having two carboxyl groups bonded thereto, and the aliphatic hydrocarbon group is usually a linear aliphatic hydrocarbon group, but has a branched structure. May have a ring structure, or may have a plurality of them.

  The polyester resin according to the present invention is a polymer having repeating units, and each repeating unit may be referred to as a “structural unit”. In addition, each structural unit may be referred to as a compound name unit or a classification name unit from which the structural unit is derived. Specifically, for example, a repeating unit derived from succinic acid may be referred to as a “succinic acid unit”, and a repeating unit derived from lactic acid may be referred to as a “lactic acid unit”. Similarly, a repeating unit derived from a diol compound is sometimes referred to as a “diol unit”, and a repeating unit derived from an aliphatic diol is sometimes referred to as an “aliphatic diol unit”. The repeating unit derived from the dicarboxylic acid compound is “dicarboxylic acid unit”, the repeating unit derived from aliphatic dicarboxylic acid is “aliphatic dicarboxylic acid unit”, and the repeating unit derived from aromatic dicarboxylic acid is “aromatic”. The “aliphatic dicarboxylic acid unit” and the repeating unit derived from the aliphatic oxycarboxylic acid may be referred to as “aliphatic oxycarboxylic acid unit”. A repeating unit derived from a hydroxycarboxylic acid having both a hydroxyl group and a carboxyl group in the same molecule may be referred to as an “oxycarboxylic acid unit”.

The aliphatic aromatic polyester (A) used in the present invention is a polyester having a succinic acid unit, an aromatic dicarboxylic acid unit and an aliphatic diol unit. The aliphatic polyester (B) used in the present invention is a polyester having an adipic acid unit and an aliphatic diol unit. Moreover, the aliphatic polyester (C) used for this invention is polyester which has the structural unit derived from oxycarboxylic acid as a main component. Here, the “main component” means that among all the carboxylic acid units and diol units in the aliphatic polyester (C), the oxycarboxylic acid unit is contained most in terms of mole.
In the present invention, when the polyester includes a specific structural unit, it means that the structural unit is incorporated into the polyester chain by polycondensation. In addition, when a specific compound is described as “mixed”, it indicates that the compound is mixed in the polyester resin.

1. Polyester resin composition The polyester resin composition of the present invention comprises an aliphatic aromatic polyester (A) having a succinic acid unit, an aromatic dicarboxylic acid unit and a diol unit, and an aliphatic polyester having an adipic acid unit and an aliphatic diol unit. It is a polyester resin composition comprising (B) and an aliphatic polyester (C) whose main component is a structural unit derived from oxycarboxylic acid.

(Biodegradation rate)
When the polyester resin composition of the present invention is formed into a film, it has a “moderate biodegradation rate” that is not early or slow in biodegradability. In the present invention, the biodegradation rate refers to the ratio (retention rate) at which the film formed from the polyester resin composition retains mechanical properties after a certain period of time in the soil. In the present invention, the tensile strength and strain as defined in JIS K7161 (1994) are used as the mechanical strength. Specifically, the mechanical strength values on the 4th and 7th days of the soil burial test described later are expressed as a percentage with the mechanical strength value when the soil burial test is not performed as 100%. The fracture stress retention rate and tensile fracture strain are referred to as tensile fracture strain retention rate.

  In the present invention, the type and copolymer composition ratio of the aliphatic aromatic polyester (A) copolymer raw material, the type and copolymer composition ratio of the aliphatic polyester (B) and aliphatic polyester (C) copolymer raw material, fat Compound composition ratio of aliphatic aromatic polyester (A), aliphatic polyester (B), and aliphatic polyester (C), aliphatic aromatic polyester (A), aliphatic polyester (B), or aliphatic polyester (C) The biodegradation rate of the polyester resin composition is adjusted according to the addition of a terminal blocking agent or a crosslinking agent during the synthesis of the polyester, the molding method and molding conditions of the polyester resin composition, etc., so that it has an “appropriate biodegradation rate”. be able to.

<Aliphatic aromatic polyester (A)>
As described above, the aliphatic aromatic polyester (A) used in the present invention essentially comprises a succinic acid unit, an aromatic dicarboxylic acid unit, and a diol unit, but further includes an aliphatic dicarboxylic acid unit described below other than succinic acid, an aromatic A polycarboxylic acid component unit other than the dicarboxylic acid unit, a polyhydric alcohol unit other than the diol unit, and a chain extender may optionally be included.

Although it does not specifically limit as aromatic dicarboxylic acid which comprises aliphatic aromatic polyester (A), From a reactive and economical viewpoint, Preferably the dicarboxylic acid or dicarboxylic acid ester whose number of aromatic rings is 4 or less is used. Dicarboxylic acids having 2 or less aromatic rings are preferably used. In addition, the aromatic ring may be substituted with a halogen atom, a sulfonic acid group, an alkyl group, or the like, and the plurality of aromatic rings may form a condensed ring, such as an alkylene group, an ether group, or a ketone group. It may be connected. Also, ester-forming derivatives such as diesters of dicarboxylic acids, acid anhydrides, acid chlorides may be used. At this time, although there is no restriction | limiting in particular as alcohol which forms dicarboxylic acid diester, It is preferable to use a C1-C4 lower alcohol from a viewpoint of productivity or a viewpoint of availability.
Specific examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, dibromoisophthalic acid, sodium sulfoisophthalic acid, phenylenedioxydicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenylether dicarboxylic acid, 4,4′-diphenyl ketone dicarboxylic acid, 4,4′-diphenoxyethane dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6 -Naphthalene dicarboxylic acid etc. are mentioned. Of these, terephthalic acid is most preferred. Specific examples of the aromatic dicarboxylic acid ester include dimethyl terephthalate, dimethyl isophthalate, dimethyl dibromoisophthalate, sodium dimethyl sulfoisophthalate, dimethyl phenylenedioxydicarboxylate, dimethyl 4,4′-diphenyldicarboxylate, 4, Dimethyl 4'-diphenyl ether dicarboxylate, dimethyl 4,4'-diphenyl ketone dicarboxylate, dimethyl 4,4'-diphenoxyethanedicarboxylate, dimethyl 4,4'-diphenylsulfone dicarboxylate, 1,4-naphthalenedicarboxylic acid, Examples include dimethyl 2,3-naphthalenedicarboxylate and dimethyl 2,6-naphthalenedicarboxylate. Of these, dimethyl terephthalate is most preferred.

Dicarboxylic acid units other than succinic acid and aromatic dicarboxylic acid constituting the aliphatic aromatic polyester (A) may be included, and the dicarboxylic acid is not particularly limited, but is a fatty acid having 2 to 40 carbon atoms. Aromatic dicarboxylic acids (excluding succinic acid) are preferred, and aliphatic dicarboxylic acids having 4 to 10 carbon atoms are particularly preferred. For example, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid and the like can be mentioned. In addition, dicarboxylic acids other than the above succinic acid and aromatic dicarboxylic acid may be used alone or in combination of two or more.
In order to obtain the aliphatic aromatic polyester used in the present invention, the dicarboxylic acid may be used as it is, or an ester-forming derivative such as a diester of dicarboxylic acid, an acid anhydride, or an acid chloride may be used. . At this time, the alcohols forming the dicarboxylic acid diester are not particularly limited, but a film excellent in biodegradability control, openability, flexibility, tear strength, and impact strength can be obtained or obtained. From the viewpoint of ease, it is preferable to use a lower alcohol having 1 to 4 carbon atoms.

  The content of the dicarboxylic acid unit constituting the aliphatic aromatic polyester (A) used in the present invention affects the control of biodegradability, flexibility, tear strength, impact strength, etc. The higher the content of succinic acid units, the more the biodegradation rate tends to be suppressed. From the viewpoint of suppressing the biodegradability rate, the total dicarboxylic acid unit is preferably 100 mol%, and the succinic acid unit is preferably contained in an amount of 30 mol% or more, more preferably 35 mol% or more, and particularly preferably 40 mol% or more. It is preferable. On the other hand, the succinic acid unit is more preferably contained in an amount of 70 mol% or less, more preferably 65 mol% or less, and particularly preferably 60 mol% or less.

  In addition, the aliphatic aromatic polyester (A) used in the present invention has all dicarboxylic acid units from the viewpoint of obtaining a film excellent in biodegradability control, openability, flexibility, tear strength, and impact strength. As 100 mol%, it is preferable to contain 30 mol% or more of aromatic dicarboxylic acid units, more preferably 35 mol% or more, and even more preferably 40 mol% or more. On the other hand, the aromatic dicarboxylic acid unit is preferably contained in an amount of 70 mol% or less, more preferably 65 mol% or less, and further preferably 60 mol% or less.

  When the aliphatic aromatic polyester (A) contains a dicarboxylic acid other than succinic acid and aromatic dicarboxylic acid, the proportion is usually 40 mol% or less, preferably 20 mol% or less in the total dicarboxylic acid.

It does not specifically limit as diol which comprises aliphatic aromatic polyester (A), An aliphatic diol, aromatic diol, polyether, etc. can be used. Of these, aliphatic diols or polyethers are preferred from the viewpoints of moldability and mechanical strength. Among the aliphatic diols, aliphatic diols or polyethers having 2 to 10 carbon atoms are more preferable, and aliphatic diols or polyethers having 4 to 6 carbon atoms are particularly preferable. Specific examples of the aliphatic diol include aliphatic chain diols such as ethylene glycol, 1,3-propanediol, and 1,4-butanediol; and aliphatic cyclic diols such as 1,4-cyclohexanedimethanol. Of these, 1,4-butanediol is particularly preferred. Specific examples of the polyether include diethylene glycol. In addition, the said aliphatic diol may be used individually, respectively and may use 2 or more types together.
The proportion of the total dicarboxylic acid and diol in the aliphatic aromatic polyester (A) is preferably 90 to 110 mol% when the total dicarboxylic acid is 100 mol%.

  The aliphatic aromatic polyester (A) used in the present invention may be a mixture of a plurality of polyester resins having different ratios of succinic acid units and aromatic dicarboxylic acid units. For example, when the total dicarboxylic acid unit is 100 mol%, the aliphatic aromatic polyester (a1) having 80 mol% succinic acid unit and 20 mol% terephthalic acid unit, 20 mol% succinic acid unit, terephthalic acid Blending with the aliphatic aromatic polyester (a2) having an acid unit of 80 mol%, the succinic acid unit and the terephthalic acid unit in the aliphatic aromatic polyester (A) are adjusted within the predetermined range according to the blend ratio. It is also possible to use it.

  The aliphatic dicarboxylic acid unit and the aliphatic diol unit constituting the aliphatic aromatic polyester (A) may be derived from a compound derived from petroleum or a compound derived from a plant raw material. However, it is desirable to include compounds derived from plant materials.

In addition, the aliphatic aromatic polyester (A) in the present invention further includes “trifunctional or higher aliphatic polyhydric alcohol”, “trifunctional or higher aliphatic polyvalent carboxylic acid or acid anhydride thereof”, “trifunctional The melt viscosity may be increased by copolymerizing any one or more of “aliphatic oxycarboxylic acids”, or the chain length may be extended by a chain extender.
Specific examples of the trifunctional aliphatic polyhydric alcohol include trimethylolpropane and glycerin, and 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, and specific examples of the tetrafunctional polyvalent carboxylic acid or its acid anhydride include: Examples include cyclopentanetetracarboxylic acid or acid anhydrides thereof.
Specific examples of the trifunctional aliphatic oxycarboxylic acid include (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, but the type (i) is preferable from the viewpoint of increasing the quality by reducing the coloring or foreign matter of the aliphatic polyester (B), specifically Is preferably malic acid. In addition, the tetrafunctional aliphatic oxycarboxylic acid component includes (iii) a type having three carboxyl groups and one hydroxyl group in the same molecule, and (iv) two carboxyl groups and two hydroxyl groups. And (v) a type having three hydroxyl groups and one carboxyl group in the same molecule, and any type can be used. Specific examples include (iii) type citric acid and (iv) type tartaric acid.

When such a trifunctional or higher functional compound is contained, these compounds may be used alone or in combination of two or more. The content of the trifunctional or higher functional compound unit is 100 mol% with respect to all structural units constituting the aliphatic aromatic polyester (A), and the lower limit is more than 0 mol%, preferably 0.01 mol% or more. The upper limit is usually 5 mol% or less, preferably 2.5 mol% or less.
The copolymer composition of the aliphatic aromatic polyester (A) can be calculated from the area ratio of the specific signal by dissolving the sample in deuterated chloroform and measuring ¹ H-NMR.

  Examples of the chain extender include diisocyanate, oxazoline, diepoxy compound, acid anhydride, and the like. Specifically, 2,4-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate. Nert, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate and the like. These addition amounts are preferably 0.1 to 5 mol% with respect to 100 mol% of all structural units of the aliphatic aromatic polyester (A).

(Properties of aliphatic aromatic polyester (A))
The aliphatic aromatic polyester (A) used in the present invention preferably has the following properties.
The average molecular weight of the aliphatic aromatic polyester (A) can be measured by gel permeation chromatography (GPC), and the mass average molecular weight using polystyrene as a standard substance is usually 10,000 or more and 1,000. However, it is preferably 20,000 or more and 500,000 or less, more preferably 50,000 or more and 400,000 or less, because it is advantageous in terms of moldability and mechanical strength.

  The melt flow rate (MFR) of the aliphatic aromatic polyester (A) is usually 0.1 g / 10 min or more and usually 100 g / 10 min 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 min or less, particularly preferably 30 g / 10 min or less.

The melting point of the aliphatic aromatic polyester (A) is preferably 70 ° C. or higher, more preferably 75 ° C. or higher, preferably 190 ° C. or lower, more preferably 160 ° C. or lower, particularly preferably 140 ° C. or lower. . When the melting point is within the above range, the moldability tends to be good. When a plurality of melting points are present, at least one melting point is preferably within the above range.
The lower limit of the elastic modulus of the aliphatic aromatic polyester (A) is preferably 180 MPa or more from the viewpoint of moldability and bag-making property, and from the viewpoint of the effect of improving the tear strength and impact strength, the elastic modulus is It is preferably 500 MPa or less.
The method for adjusting the melting point and elastic modulus of the aliphatic aromatic polyester (A) is not particularly limited. For example, the type of copolymerization component other than succinic acid can be selected, or the copolymerization ratio of each can be adjusted. It is possible to adjust by combining them.

  The acid value (AV) of the aliphatic aromatic polyester (A) is not particularly limited. However, the lower the acid value, the better the hydrolysis resistance, so the upper limit is preferably 100 μeq / g or less. More preferably, it is 80 μeq / g or less. In order to reduce the acid value, the amount of the catalyst is decreased or the melt polycondensation temperature is decreased. However, since the melt polycondensation reaction rate may be decreased, the lower limit of the acid value is usually 1 μeq / g or more. It is.

<Aliphatic polyester (B)>
The aliphatic polyester (B) used in the present invention essentially comprises an adipic acid unit and an aliphatic diol unit as described above, but further includes an aliphatic dicarboxylic acid unit other than adipic acid and an aromatic dicarboxylic acid unit described later. It may optionally have a polyvalent carboxylic acid component unit, a polyhydric alcohol unit other than a diol unit, and a chain extender.

  The content of all dicarboxylic acid units constituting the aliphatic polyester (B) used in the present invention affects the tear strength, impact strength, biodegradability control, openability, flexibility, etc. Among them, the tear strength It greatly affects the control of From the viewpoint of tear strength, the total dicarboxylic acid unit is preferably 100 mol%, and the adipic acid unit is preferably contained in an amount of 10 mol% or more, more preferably 20 mol% or more, and particularly preferably 30 mol% or more. On the other hand, it is more preferable to contain 60 mol% or less of adipic acid units, still more preferably 55 mol% or less, and particularly preferably 50 mol% or less.

The dicarboxylic acid unit other than adipic acid constituting the aliphatic polyester (B) may be included, and the dicarboxylic acid is not particularly limited, but is preferably an aliphatic dicarboxylic acid having 2 to 40 carbon atoms, An aliphatic dicarboxylic acid having a number of 2 or more and 10 or less is particularly preferred. For example, succinic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid and the like can be mentioned. In addition, dicarboxylic acids other than the adipic acid may be used alone or in combination of two or more. The content of aliphatic dicarboxylic acid units other than adipic acid is preferably 90 mol% or less, more preferably 80 mol% or less, and particularly preferably 70 mol% or less, based on 100 mol% of all dicarboxylic acid units. It is preferable. On the other hand, the aliphatic dicarboxylic acid other than the adipic acid unit is more preferably contained in an amount of 40 mol% or more, more preferably 45 mol% or more, and particularly preferably 50 mol% or more.
In addition, in order to obtain the aliphatic polyester used for this invention, dicarboxylic acid may be used as it is, and ester-forming derivatives, such as diester of dicarboxylic acid, an acid anhydride, and an acid chloride, may be used. At this time, the alcohols forming the dicarboxylic acid diester are not particularly limited, but a film excellent in biodegradability control, openability, flexibility, tear strength, and impact strength can be obtained or obtained. From the viewpoint of ease, it is preferable to use a lower alcohol having 1 to 4 carbon atoms.

  The aliphatic polyester (B) used in the present invention may be a mixture of a plurality of polyester resins having different ratios of adipic acid units and aliphatic dicarboxylic acid units other than adipic acid. For example, when the total dicarboxylic acid unit is 100 mol%, the aliphatic aromatic polyester (b1) having 80 mol% succinic acid unit and 20 mol% adipic acid unit, 20 mol% succinic acid unit, adipine The aliphatic aromatic polyester (b2) having an acid unit of 80 mol% is blended, and the succinic acid unit and the adipic acid unit in the aliphatic polyester (B) are adjusted within the predetermined range according to the blend ratio. It is also possible to use it.

It does not specifically limit as aliphatic diol which comprises aliphatic polyester (B). Of these, aliphatic diols having 2 to 10 carbon atoms are more preferable, and aliphatic diols having 4 to 6 carbon atoms are particularly preferable. Specific examples of the aliphatic diol include aliphatic chain diols such as ethylene glycol, 1,3-propanediol, and 1,4-butanediol; and aliphatic cyclic diols such as 1,4-cyclohexanedimethanol. Of these, 1,4-butanediol is particularly preferred. In addition, the said aliphatic diol may be used individually, respectively and may use 2 or more types together.
The proportion of all dicarboxylic acids and diols in the aliphatic polyester (B) is preferably 90 to 110 mol% when the total dicarboxylic acids are 100 mol%.

  The aliphatic dicarboxylic acid unit and the aliphatic diol unit constituting the aliphatic polyester (B) may be derived from a compound derived from petroleum or a compound derived from a plant raw material, It is desirable to include compounds derived from plant materials.

The aliphatic polyester (B) may further contain a polyether such as diethylene glycol, and the above-mentioned “trifunctional or higher aliphatic polyhydric alcohol”, “trifunctional or higher aliphatic polyhydric carboxylic acid or acid anhydride thereof”. Product ”or“ trifunctional aliphatic oxycarboxylic acid ”may be used to increase the melt viscosity by copolymerization, and the chain length may be extended by the above-described chain extender. It may be.
When a trifunctional or higher functional compound is contained, these compounds may be used alone or in combination of two or more. Further, the content is 100 mol% of all structural units constituting the aliphatic polyester (B), the lower limit is more than 0 mol%, preferably 0.01 mol% or more, and the upper limit is usually 5 mol% or less, preferably 2.5 mol% or less.
Moreover, when it contains the said chain extender, the content is 0.1-5 mol%, when all the structural units of aliphatic polyester (B) are 100 mol%.
The copolymerization composition of the aliphatic polyester (B) can be calculated from the area ratio of the specific signal by dissolving the sample in deuterated chloroform and measuring ¹ H-NMR.

(Properties of aliphatic polyester (B))
The aliphatic polyester (B) used in the present invention preferably has the following properties.
The average molecular weight of the aliphatic polyester (B) can be measured by gel permeation chromatography (GPC), and the mass average molecular weight using polystyrene as a standard substance is usually 10,000 or more and 1,000,000. Although it is below, since it is advantageous in terms of moldability and mechanical strength, it is preferably 20,000 or more and 500,000 or less, more preferably 50,000 or more and 400,000 or less.

  The melt flow rate (MFR) of the aliphatic polyester (B) is usually 0.1 g / 10 min or more and usually 100 g / 10 min 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 min or less, particularly preferably 30 g / 10 min or less.

The melting point of the aliphatic polyester (B) is preferably 70 ° C. or higher, more preferably 75 ° C. or higher, preferably 120 ° C. or lower, more preferably 110 ° C. or lower, particularly preferably 100 ° C. or lower. When the melting point is within the above range, the moldability tends to be good. When a plurality of melting points are present, at least one melting point is preferably within the above range.
The lower limit of the elastic modulus of the aliphatic polyester (B) is preferably 180 MPa or more from the viewpoint of moldability and bag-making property, and the elastic modulus is 500 MPa or less from the viewpoint of the effect of improving the tear strength and impact strength. It is preferable that
The method for adjusting the melting point and elastic modulus of the aliphatic polyester (B) is not particularly limited. For example, the type of copolymerization component other than adipic acid can be selected, the copolymerization ratio of each can be adjusted, It is possible to adjust by combining.

  The acid value (AV) of the aliphatic polyester (B) is not particularly limited. However, the lower the acid value, the better the hydrolysis resistance, so the upper limit is preferably 100 μeq / g or less. Preferably, it is 80 μeq / g or less. In order to reduce the acid value, the amount of the catalyst is decreased or the melt polycondensation temperature is decreased. However, since the melt polycondensation reaction rate may be decreased, the lower limit of the acid value is usually 1 μeq / g or more. It is.

<Aliphatic polyester (C)>
The aliphatic polyester (C) used in the present invention contains the most oxycarboxylic acid units among all the structural units in the aliphatic polyester (C). The aliphatic polyester (C) used in the present invention may optionally further contain a structural unit other than the oxycarboxylic acid unit and the above-mentioned chain extender, and among them, all the structural units of the aliphatic polyester (C). Is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 97.5 mol% or more of oxycarboxylic acid units. It is particularly preferred that all carboxylic acid units consist of oxycarboxylic acid units.

  Examples of the oxycarboxylic acid that gives an oxycarboxylic acid unit to the aliphatic polyester (C) used in the present invention include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 3 -Hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, 3-hydroxyhexanoic acid, 2-hydroxy-3,3-dimethylbutyric acid Bifunctional aliphatic hydroxycarboxylic acids having 2 or more carbon atoms such as 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, 2-methyllactic acid and 2-hydroxycaproic acid; trifunctional such as malic acid Aliphatic hydroxycarboxylic acids or acid anhydrides thereof; tetrafunctional aliphatic hydroxycarboxylic acids such as citric acid and tartaric acid Class or acid anhydrides; caprolactone, butyrolactone, lactones such as valerolactone, or lower alkyl esters or intramolecular esters. When optical isomers exist in these, any of D-form, L-form and racemic form may be sufficient, and a form may be a solid, a liquid, or aqueous solution. These aliphatic oxycarboxylic acids may be used alone or in combination of two or more.

  In the present invention, among these, a bifunctional aliphatic hydroxycarboxylic acid is preferable, and particularly preferable is lactic acid (D-lactic acid or L-lactic acid) or glycolic acid, and lactic acid is most preferable. In addition, when aliphatic polyester (C) contains oxycarboxylic acid other than lactic acid or glycolic acid, it is preferable to use the content at 15 mol% or less in all the structural units of aliphatic polyester (C).

  In the present invention, the aliphatic polyester (C) is particularly preferably polylactic acid. The polylactic acid-based resin may be any polymerized with a lactic acid monomer as an essential component. Examples of the lactic acid monomer include poly L-lactic acid whose structural unit is L-lactic acid, poly D-lactic acid whose structural unit is D-lactic acid, poly DL-lactic acid whose structural units are L-lactic acid and D-lactic acid, And mixtures thereof. In addition, the polylactic acid preferably has a molar ratio of D-lactic acid: L-lactic acid = 100: 0 to 85:15 or 0: 100 to 15:85. It is also possible to blend other polylactic acids having different constituent ratios of D-lactic acid and L-lactic acid. A polylactic acid resin having only D-lactic acid or L-lactic acid as a structural unit is a crystalline resin, has a high melting point, and tends to have excellent heat resistance and mechanical properties.

  The oxycarboxylic acid unit constituting the aliphatic polyester (C) may be derived from a compound derived from petroleum or a compound derived from a plant material, but is derived from a plant material. It is desirable to include the above compounds.

When the aliphatic polyester (C) contains other structural units derived from a compound other than the oxycarboxylic acid, examples of the compound include the aliphatic diols, polyethers, and aliphatic dicarboxylic acids described above. The content of other structural units in the aliphatic polyester (C) is such that the total structural unit of the aliphatic polyester (C) is 100 mol%, and the lower limit of the other structural units is more than 0 mol%, preferably 0.01 The upper limit is usually 5 mol% or less, preferably 2.5 mol% or less.
Moreover, when aliphatic polyester (C) contains the above-mentioned chain extender, the addition amount is preferably 0.1 to 5 mol% when the total structural unit of aliphatic polyester (C) is 100 mol%.
The copolymerization composition of the aliphatic polyester (C) can be calculated from the area ratio of the specific signal by dissolving the sample in deuterated chloroform and measuring ¹ H-NMR.

  The aliphatic polyester (C) can be obtained by a known method such as a method of directly dehydrating polycondensation using the above-mentioned raw materials, a method of ring-opening polymerization of a cyclic dimer of lactic acid or hydroxycarboxylic acid, and production by a microorganism. it can. For example, in the condensation polymerization method, an aliphatic polyester (C) having an arbitrary composition and crystallinity can be obtained by directly dehydrating condensation polymerization of L-lactic acid or D-lactic acid, or a mixture thereof. In the ring-opening polymerization method (lactide method), an aliphatic polyester (C) is obtained by using lactide, which is a cyclic dimer of lactic acid, using a suitable catalyst while using a polymerization regulator as necessary. be able to. The lactide includes L-lactide, which is a dimer of L-lactic acid, D-lactide, which is a dimer of D-lactic acid, DL-lactide, which is a dimer of D-lactic acid and L-lactic acid. The aliphatic polyester (C) having an arbitrary composition and crystallinity can be obtained by mixing and polymerizing as necessary.

(Properties of aliphatic polyester (C))
The aliphatic polyester (C) used in the present invention preferably has the following properties.
The mass average molecular weight of the aliphatic polyester (C) is preferably 60,000 or more in order to develop practical properties such as mechanical properties and heat resistance. On the other hand, in order to obtain a melt viscosity suitable for molding processability, it is preferably 700,000 or less. Among these, the mass average molecular weight is more preferably 80,000 to 400,000, and particularly preferably 100,000 to 300,000.

  When the melt flow rate (MFR) of the aliphatic polyester (C) 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 100 g / 10 min or less, preferably It is 50 g / 10 min or less, particularly preferably 30 g / 10 min or less.

  The acid value (AV) of the aliphatic polyester (C) is not particularly limited, but since the lower acid value is excellent in hydrolysis resistance, the upper limit is preferably 100 μeq / g or less. Preferably, it is 50 μeq / g or less. In order to reduce the acid value, the amount of the catalyst is decreased or the melt polycondensation temperature is decreased. However, since the melt polycondensation reaction rate may be decreased, the lower limit of the acid value is usually 1 μeq / g or more. It is.

<Blend ratio of polyester resin composition>
The ratio of the aliphatic aromatic polyester (A), the aliphatic polyester (B) and the aliphatic polyester (C) in the polyester resin composition of the present invention is not particularly limited, but the aliphatic aromatic polyester (A) is usually 10%. It is -40 mass%, Preferably it is 15-35 mass%, and aliphatic polyester (B) is 50-80 mass% normally, Preferably it is 55-75 mass%. In the case of forming into a film using the polyester resin composition of the present invention, a suitable biodegradability is obtained, and at the same time, a lower limit of the content of the aliphatic polyester (C) from the viewpoint of obtaining a film excellent in impact strength. Is preferably 1% by mass or more, more preferably 3% by mass or more, and still more preferably 5% by mass or more. On the other hand, from the viewpoint of appropriate biodegradability, tear strength, and film physical properties, the upper limit of the content of the aliphatic polyester (C) is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less. preferable.

  The polyester resin composition of the present invention may contain other components in addition to the aliphatic aromatic polyester (A), the aliphatic polyester (B), and the aliphatic polyester (C). The ratio of the aliphatic polyester (B) to the total of the aromatic polyester (A), the aliphatic polyester (B) and the aliphatic polyester (C) is preferably 50% by mass or more and 80% by mass or less for the same reason. More preferably, it is 55% by mass or more, and more preferably 75% by mass or less. Further, the ratio of the aliphatic polyester (C) to the total is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more, and more preferably 20% by mass or less. Especially preferably, it is 15 mass% or less.

<Other ingredients>
The polyester resin composition of the present invention includes additives such as slip agents, fillers (fillers), plasticizers, antistatic agents, starches, light-resistant stabilizers, ultraviolet absorbers, heat stabilizers, end-capping agents, and others. The compounding component of can be contained. These additives and other compounding components may be used alone or in combination of two or more. In order to exhibit the performance of these additives without impairing the properties of the resin composition, the total amount of these additives and other compounding components is 0.01% by mass or more and 40% with respect to the polyester resin composition of the present invention. It is preferable to blend so as to contain at most mass%. These additives and other compounding ingredients may be added at the time of synthesis of the aliphatic aromatic polyester (A), the aliphatic polyester (B) or the aliphatic polyester (C). A) A method in which the aliphatic polyester (B) or the aliphatic polyester (C) is once pelletized and then melt-mixed in an extruder is preferable.

(Slip agent)
It is preferable to include a slip agent in the polyester resin composition of the present invention because the moldability of the resin composition can be improved.
As the slip agent, known ones can be used without particular limitation. Specifically, paraffin such as paraffin oil and solid paraffin, higher fatty acids such as stearic acid and palmitic acid, palmityl alcohol, stearyl alcohol Higher alcohols such as calcium stearate, zinc stearate, barium stearate, aluminum stearate, magnesium stearate, sodium palmitate, etc., fatty acid salts such as butyl stearate, glycerin monostearate, diethylene glycol monostearate Esters, stearamide, methylene bis stearamide, ethylene bis stearamide, ethylene diamide of oxystearic acid, methylolamide, oleylamide, stearamide, erucic acid Fatty amides, such as bromide, etc., carnauba wax, and the like waxes such as montan wax. In addition, a slip agent and wax may be used individually by 1 type, and may use 2 or more types by arbitrary ratios and combinations. Of these, erucic acid amide is particularly preferred.
In this invention, content of these slip agents is 0.01-2 mass% normally in a resin composition, and it is preferable that it is the range of 0.05-0.5 mass%.

(Filler)
When a filler (filler) is included in the resin composition according to the present invention, it is obtained when the resin composition is made into a film by stabilizing the film composition by improving the fluidity and crystallization speed of the resin composition. It is possible to prevent mechanical properties such as rigidity of the film, reduce anisotropy, and prevent blocking between films. Further, when the film is formed into a bag, the bag mouth can be easily opened. Moreover, a film or a bag can be colored, and the opacity, light shielding property and light reflection property can be improved.

Depending on the shape of the filler, there are fibrous, powdery, plate-like, and needle-like fillers, and powdery and plate-like fillers are particularly preferable. As the particulate filler, mineral particles such as zeolite, diatomaceous earth, silica and quartz powder; metal carbonate particles such as calcium carbonate, magnesium carbonate and heavy calcium carbonate; metal silicates such as calcium silicate, aluminum silicate and magnesium silicate Particles; Metal oxide particles such as alumina, silica, zinc oxide, and titanium oxide; Metal hydroxide particles such as aluminum hydroxide, calcium hydroxide, and magnesium hydroxide; Carbon particles such as carbon black. Examples of the plate filler include talc, kaolin, clay, mica, and calcium carbonate.
In the present invention, silica, zinc oxide, talc, kaolin, clay, mica, calcium carbonate and the like are preferably used from the viewpoint of openability, rigidity and mechanical strength, talc and calcium carbonate are preferable, and talc is particularly used. It is preferable. From the viewpoint of coloring the film or bag and improving the light shielding property or light reflecting property, carbon black or titanium oxide may be used.

  In the present invention, the surface-treated filler may be used. In this case, the filler is improved in dispersibility, the fluidity of the resin composition is improved, and the smoothness and opening of the film are improved. Can be improved. Furthermore, it can be expected that additives such as a plasticizer to be blended in the resin composition are reduced by surface treatment. As a surface treatment method for the filler, it is common to mix the surface treatment agent and the filler by a generally known method, but the method is not limited to the treatment method. Examples of the surface treatment agent include straight chain fatty acids having 6 to 40 carbon atoms, branched chain fatty acids, and ester compounds thereof.

  In the present invention, the particle diameter of the filler is usually 0.08 to 25 μm in volume average particle diameter, more preferably 0.1 to 5 μm, in a dispersed state of the filler in a molded body such as a film or a resin composition. is there. Among these, from the viewpoint of facilitating the opening of the bag and preventing blocking, coloring the film and bag, and improving the light shielding property or light reflecting property, a filler having a volume average particle size of 1 to 5 μm. Is preferably used. On the other hand, stabilization at the time of film molding by improving the fluidity and crystallization speed of the resin composition, when the resin composition is a film, improvement in mechanical properties such as rigidity of the obtained film, From the viewpoint of reduction or the like, it is preferable to use a filler having a volume average particle diameter of 0.1 to 1 μm. A filler may be used individually by 1 type, and 2 or more types may be mixed and used for it. In addition, the lower limit of the filler content is preferably 0.01% by mass or more in order to express blocking resistance with respect to the polyester resin composition, so that the tear strength and impact resistance are not deteriorated. The upper limit is usually 40% by mass, preferably 10% by mass or less, more preferably 2% by mass or less.

  In the present invention, the method for measuring the volume average particle diameter is not particularly limited, but the particles dispersed in the dispersion medium are measured by a sedimentation method, measured by a laser scattering analysis, or measured by a laser Doppler method. be able to.

  When talc is used as a filler in the present invention, the volume average particle diameter is preferably 3 to 20 μm from the viewpoint of preventing blocking, and when applied to a transparent or white film, the whiteness is 90% or more. Those are preferred. Further, from the viewpoint of preventing foaming during molding, the water content is preferably 0.3% by mass or less.

(End sealant)
A terminal blocking agent can be added to the polyester resin composition of the present invention mainly for the purpose of suppressing hydrolysis due to moisture in the air. Examples of the end-capping agent include carbodiimide compounds, epoxy compounds, oxazoline compounds, and the like, but the following carbodiimide compounds are preferably used because they are easily available industrially and have high safety.
Examples of carbodiimide compounds include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, diphenylcarbodiimide, di-tert-butylcarbodiimide, di-β-naphthylcarbodiimide, and other US patents; No. 2944195, Japanese Examined Patent Publication No. 47-33279, J. Pat. Org. Chem. 28, p2069-2075 (1963), and Chemical Review 1981, 81, No. 4, p. The polycarbodiimide compound manufactured from a monocarbodiimide and organic diisocyanate can be illustrated by the method described in 619-621 grade | etc.,.

  These carbodiimide compounds may be used individually by 1 type, and 2 or more types may be mixed and used for them. In the present invention, it is particularly preferable to use a polycarbodiimide compound, and the degree of polymerization of the lower limit is 2 or more, preferably 4 or more, and the upper limit is preferably 40 or less, more preferably 20 or less. The content of these carbodiimides is preferably 0.1 to 5% by mass with respect to the entire resin composition.

(Plasticizer)
The fluidity of the resin composition can be improved by adding a plasticizer to the polyester resin composition of the present invention. In particular, when a filler is included in the resin composition, the viscosity of the resin composition may increase and the flowability of the resin composition may deteriorate, and the improvement effect by adding a plasticizer to the resin composition may be large.
As a plasticizer, a well-known thing can be used without being specifically limited. For example, dimethyl adipate, diethyl adipate, diisopropyl adipate, di-n-propyl adipate, dibutyl adipate, di-2-ethylhexyl adipate, diisobutyl adipate, diisodecyl adipate, dibutyl diglycol adipate, adipic acid Fatty acid esters such as -1,3-butylene glycol, di-2-ethylhexyl azelate, diisooctyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, tributyl acetylcitrate; diethyl maleate, dibutyl maleate, Unsaturated fatty acid esters such as dioctyl maleate, dibutyl fumarate, dioctyl fumarate; diisooctyl phthalate, diisodecyl phthalate, di-2-ethylhexyl phthalate, trioctyl trimellitic acid Aromatic carboxylic acid esters such as Le;

  Glycerin esters such as triacetin, glycerol diacetomonopropionate, glycerol diacetomonocaprylate, glycerol diacetomonocaprate, glycerol diacetomonolaurate, glycerol diacetomonooleate, glycerol monoacetomonobehenate, glycerol monoacetomonostearate; Polyalkylene glycol esters such as triethylene glycol diacetate; polyglycerin fatty acid esters such as diglycerin acetate, decaglycerin propionate, tetraglycerin caprylate, decaglycerin laurate, decaglycerin oleate, decaglycerin behenate; epoxidation And natural product derivatives such as soybean oil and rosin derivatives. In this invention, it is preferable to use these plasticizers in 0.05-10 mass% in a resin composition.

(Antistatic agent)
The polyester resin composition of the present invention may contain an antistatic agent. Any antistatic agent can be used as long as the effects of the present invention are not significantly impaired. The antistatic agent is preferably a surfactant type nonionic, cationic or anionic.
Nonionic antistatic agents include glycerin fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, alkyldiethanolamine, hydroxyalkyl monoethanolamine, polyoxyethylene alkylamine, polyoxyethylene alkylamine fatty acid ester alkyldiethanol Amides etc. are mentioned. Of these, alkyldiethanolamines are preferred.
Examples of the cationic antistatic agent include tetraalkylammonium salts and trialkylbenzylammonium salts.
Examples of the anionic antistatic agent include alkyl sulfonates, alkyl benzene sulfonates, and alkyl phosphates. Among these, alkylbenzene sulfonate is preferable because it has good kneading properties with a resin and high antistatic effect.

  In the present invention, the content of the antistatic agent is arbitrary as long as the effects of the present invention are not significantly impaired. However, in order to exert the effect of improving the antistatic property, the content of the antistatic agent relative to the resin composition Is preferably 0.5% by mass or more, more preferably 1% by mass or more, and in order not to adversely affect the surface of the resin composition, the upper limit of the content of the antistatic agent relative to the resin composition Is preferably 5% by mass or less, more preferably 3% by mass or less.

(Light stabilizer)
For the purpose of improving light resistance, a light-resistant stabilizer can be added to the polyester resin composition of the present invention.
Examples of light-resistant stabilizers include bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester, bis (1,2,2,6,6-pentamethyl-4-piperidyl) ) 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-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, poly [[6- (1,1,3,3-tetramethylbutyl) amino-1,3 -Triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] Hindered amine stabilizers and the like. In the present invention, the light-resistant stabilizer is preferably used in combination with a later-described ultraviolet absorber, and a combination of a hindered amine stabilizer and an ultraviolet absorber is particularly preferable.

  In the present invention, the amount of the light-resistant stabilizer to be mixed is preferably 100 ppm by mass or more, more preferably 200 ppm by mass or more, more preferably 200 ppm by mass or less, more preferably 5 ppm by mass or less, with respect to the resin composition. Is 1 mass ppm or less, more preferably 0.5 mass ppm or less. Below this range, the effect of the light-resistant stabilizer tends to be small. On the other hand, if it exceeds this range, the production cost tends to be high, the heat resistance of the resin composition tends to be inferior, and the light-resistant stabilizer bleed out.

(UV absorber)
An ultraviolet absorbent can be added to the polyester resin composition of the present invention for the purpose of improving light resistance. In addition, as above-mentioned, it is preferable to use a ultraviolet absorber and a hindered amine light-resistant stabilizer together.
UV absorbers include benzophenone UV absorbers, benzotriazole UV absorbers, triazine UV absorbers, salicylic acid UV absorbers, cyanoacrylate UV absorbers, benzoxazine UV absorbers, and cyclic imino ester UV rays. Although an absorber etc. are mentioned, a benzophenone type ultraviolet absorber, a benzotriazole type ultraviolet absorber, and a triazine type ultraviolet absorber are more preferable from a durable viewpoint. In addition, it is preferable to use two or more different types of ultraviolet absorbers in combination.
Examples of the benzotriazole ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2,2 ′, 4,4′-. Examples include tetrahydroxybenzophenone and bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane. Examples of the benzotriazole ultraviolet absorber include 2- (2H-benzotriazol-2-yl) -4-6-bis (1-methyl-1-phenylethyl) phenol and 2- (2′-hydroxy). -5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl)- 6- (2Hbenzotriazol-2-yl) phenol]. Examples of the triazine-based ultraviolet absorber include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] phenol.

  In the present invention, the amount of the ultraviolet absorber to be mixed is arbitrary as long as the effects of the present invention are not significantly impaired, but the lower limit of the resin composition is preferably 100 mass ppm or more, more preferably 200 mass ppm or more. The upper limit is preferably 5% by mass or less, more preferably 2% by mass or less, and still more preferably 0.5% by mass or less. Below this range, the effect of the ultraviolet absorber tends to decrease. On the other hand, if it exceeds this range, the production cost tends to be too high, the heat resistance of the biodegradable resin composition tends to be inferior, or the ultraviolet absorber bleeds out.

(Heat stabilizer)
A heat stabilizer can be added to the polyester resin composition of the present invention for the purpose of improving durability. As the heat stabilizer, an antioxidant is preferably used in order to mainly suppress deterioration due to oxidation. Examples of the heat stabilizer include 2,6-di-tert-butyl-4-methylphenol (dibutylhydroxytoluene: abbreviated as BHT), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), penta Erythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′ , A "-(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) -trio 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 [3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide, [[3,5-bis (1, Hindered phenol compounds such as 1-dimethylethyl) -4-hydroxyphenyl] methyl] butylmalonate; tridecyl phosphite, diphenyldecyl phosphite, tetrakis (2,4- Di-tert-butylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphonite, bis [2,4-bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester Phosphorus compounds such as phosphoric acid and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite; reaction of 3-hydroxy-5,7-di-tert-butyl-furan-2-one with xylene Lactone compounds such as a living organism; sulfur compounds such as dilauryl thiodipropionate and distearyl thiodipropionate.

  The additive amount of the heat stabilizer is preferably 100 ppm by mass or more, more preferably 200 ppm by mass or more, in order to develop the effect of the heat stabilizer with respect to the resin composition. In order to suppress bleed out of the stabilizer, the upper limit is preferably 5 parts by mass or less, more preferably 1 part by mass or less, and still more preferably 0.5 parts by mass or less.

(Other ingredients)
In addition to the additives described above, the polyester resin composition of the present invention includes various known ingredients such as surface wetting improvers, flame retardants, mold release agents, incineration aids, dyes, pigments, dispersion aids, A surfactant, a hydrolysis inhibitor, a crystal nucleating agent, a compatibilizing agent and the like may be contained.

Starch can be added to the polyester resin composition of the present invention for the purpose of controlling the biodegradation rate and the decay rate in soil.
Specific examples of starch include corn starch, waxy corn starch, high amylose corn starch, wheat starch, rice starch, potato starch, sweet potato starch, tapioca starch, pea starch, etc., both of which are unmodified and modified products. it can. Modification includes all modification methods such as chemical, physical, and biological. Chemical modification includes esterification, etherification, oxidation, reduction, part or all of the structural units of carbohydrates (polysaccharides), It shows that it is modified by a chemical reaction such as coupling, dehydration, hydrolysis, dehydrogenation, halogenation, etc., and particularly shows that a hydroxyl group is etherified or esterified. Also, physical modification indicates changing physical properties such as changing the crystallinity. Biological degeneration refers to changing a chemical structure or the like using a living organism.
Also, the polyester resin composition of the present invention and synthetic resins such as polyamide, polyvinyl alcohol, cellulose ester and thermoplastic polyester elastomer; recycled raw materials such as recovered polyethylene terephthalate; starch, cellulose, paper, wood powder, chitin / chitosan, insulator It is also possible to prepare a composition by blending animal / plant material fine powders such as shell powder and walnut shell powder.

2. Production Method of Polyester Resin Composition A known method can be applied as a production method of the resin composition according to the present invention. For example, the pellets of the aliphatic aromatic polyester (A), the pellets of the aliphatic polyester (B), the pellets of the aliphatic polyester (C) and various additives are dry blended, and the raw material chips are melt-mixed in the same extruder. The method, the method of mixing after melt | dissolving with each separate extruder, etc. are mentioned. As the extruder, a single screw or a twin screw extruder can be used. Further, various additives can be added and blended when the aliphatic aromatic polyester (A), the aliphatic polyester (B) and the aliphatic polyester (C) are mixed and heated and melted. At this time, a blending oil or the like can be used for the purpose of uniformly dispersing the additive. Meanwhile, the aliphatic aromatic polyester (A), the aliphatic polyester (B) and the aliphatic polyester (C), and if necessary, various additives are directly supplied to the molding machine to prepare a resin composition, It is also possible to obtain a molded body such as a film as it is.

<Method for producing aliphatic aromatic polyester (A)>
The aliphatic aromatic polyester (A) which is an essential component of the polyester resin composition of the present invention can be produced by a known polymerization method. These known methods are roughly classified into a so-called direct polymerization method using an aromatic dicarboxylic acid as a main raw material and an ester exchange method using an aromatic dicarboxylic acid dialkyl ester as a main raw material as an aromatic dicarboxylic acid component of the raw material. The former has the difference that water is produced in the initial esterification reaction, and the latter produces alcohol in the initial transesterification reaction, but the availability of raw materials, ease of distillate treatment, It can be appropriately selected depending on the height and the like. Moreover, aliphatic dicarboxylic acid and aromatic dicarboxylic acid dialkyl ester can be used in combination. At this time, the esterification reaction and the transesterification step are performed simultaneously.
Hereinafter, an example of a method for producing an aliphatic aromatic polyester (A) using 1,4-butanediol as a raw material diol, succinic acid as a raw material aliphatic dicarboxylic acid component, and dimethyl terephthalate as a raw material aromatic dicarboxylic acid component However, the present invention is not limited to this.

In the present invention, in the production of the aliphatic aromatic polyester (A), 1,4-butanediol, succinic acid, and dimethyl terephthalate are mixed to form a slurry, and the resulting slurry is esterified and / or transesterified. Thus, a polyester oligomer is obtained. Furthermore, polyester is obtained from the obtained polyester oligomer by a melt polycondensation reaction.
Examples of the esterification reaction or transesterification reaction in the production of the aliphatic aromatic polyester (A) and the subsequent polycondensation reaction catalyst include titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate, tetrabutyl titanate; tetraphenyl titanate, etc. Titanium compounds such as titanium phenolate are preferably used. These titanium compounds may be used individually by 1 type, and may be used in combination of 2 or more types. The addition amount of the titanium compound is 30 to 200 ppm, preferably 40 to 150 ppm, more preferably 50 to 130 ppm with respect to the aliphatic aromatic polyester (A) produced as the titanium amount.
Furthermore, as a catalyst other than a titanium compound, an antimony compound, a germanium compound, a tin compound, or the like can be used. Further, in addition to magnesium compounds such as magnesium acetate and magnesium hydroxide, transitions such as calcium compounds, manganese compounds, and zinc compounds A metal can be used in combination. In addition, it is more preferable to use a titanium compound and a magnesium compound as a polymerization catalyst, and it is especially preferable to use it in the range whose equivalent ratio of magnesium and titanium is 0.1-10.
It is preferable to add the titanium compound separately at the start of transesterification and before the polycondensation reaction. Further, the addition timing of other metals such as a magnesium compound is preferably added from the viewpoint of polymerization activity and color tone after the transesterification and before the start of polymerization. In the case of an esterification method using succinic acid and terephthalic acid as main components, it is preferable to add a titanium compound and a magnesium compound during the polycondensation reaction.

  The production of the aliphatic aromatic polyester (A) can employ either a batch type or a continuous type. As the reaction conditions, for example, in the case of an esterification reaction, the esterification reaction may be performed at 180 ° C. to 250 ° C., preferably 185 to 230 ° C. for 2 to 4 hours. In the case of the transesterification reaction, the transesterification reaction may be carried out at 180 ° C. to 250 ° C., preferably 190 to 245 ° C. for 2 to 4 hours. In addition, the polycondensation reaction to be performed next may be performed at 200 to 250 ° C. for 2 to 7 hours under a reduced pressure of 400 Pa or less. The melt polymerization temperature is preferably a temperature of 250 ° C. or less, particularly preferably a temperature of 250 ° C. or less, more preferably 240 ° C. or less, still more preferably 235 ° C. or less, most preferably 230 ° C. It is below ℃.

  The aliphatic aromatic polyester (A) obtained by the polycondensation reaction can be granulated by a known method. For example, there is a method in which a polymer is extracted in the form of a strand from the bottom of a polycondensation reaction tank, cooled with water, or after water cooling, and then cut with a cutter to form pellets or chips of a predetermined shape. In the melted aliphatic aromatic polyester (A), the above-mentioned various additives such as slip agents, fillers, plasticizers, antistatic agents, light-resistant stabilizers, heat stabilizers, ultraviolet absorbers and the like are included in the present invention. You may granulate, after adding in the range by which the characteristic of this polyester resin composition is not impaired.

<Method for producing aliphatic polyester (B)>
The aliphatic polyester (B) which is one of the essential components of the polyester resin composition of the present invention is the same polymerization method as the aliphatic aromatic polyester (A) except that at least adipic acid and an aliphatic diol are used. Can be manufactured.

<Method for producing aliphatic polyester (C)>
The aliphatic polyester (C) that is one of the essential components of the polyester resin composition of the present invention can be produced by a known polymerization method.
Hereinafter, although an example of the manufacturing method of aliphatic polyester (C) which has lactic acid as a main component as a raw material is shown, in this invention, it is not limited to this.

In the present invention, the aliphatic polyester (C) is usually produced by esterifying a raw material mainly containing lactic acid to obtain a polyester oligomer. Furthermore, polyester is obtained from the obtained polyester oligomer by a melt polycondensation reaction.
As the polycondensation reaction catalyst in the production of the aliphatic polyester (C), for example, a metal compound soluble in a reaction system such as germanium, titanium, antimony, tin, magnesium, calcium, zinc is preferably used. Among these, germanium compounds are preferable, and organic germanium compounds such as tetraalkoxygermanium, or inorganic germanium compounds such as germanium oxide and germanium chloride are particularly preferable. In view of price and availability, germanium oxide, tetraethoxygermanium, tetrabutoxygermanium, and the like are particularly preferable. These germanium compounds may be used individually by 1 type, and may be used in combination of 2 or more types. The addition amount of these catalysts is 10-30000 mass ppm with respect to the aliphatic polyester (C) produced | generated as a metal amount, More preferably, it is 50-15000 mass ppm.
Furthermore, as a catalyst other than a titanium compound, an antimony compound, a germanium compound, a tin compound, or the like can be used. Further, in addition to magnesium compounds such as magnesium acetate and magnesium hydroxide, transitions such as calcium compounds, manganese compounds, and zinc compounds A metal can be used in combination. In addition, it is more preferable to use a titanium compound and a magnesium compound as a polymerization catalyst, and it is especially preferable to use in the range whose equivalent ratio of magnesium and titanium is 0.1-10.
The addition timing of the catalyst is not particularly limited as long as it is before the polycondensation reaction, but it may be added when the raw materials are charged or may be added at the start of pressure reduction. Among these, it is preferable to add the oxycarboxylic acid simultaneously with the aliphatic oxycarboxylic acid when charging the raw materials, or to dissolve the catalyst in the aliphatic oxycarboxylic acid and its aqueous solution.

  The production of the aliphatic polyester (C) can employ either a batch type or a continuous type. As the reaction conditions, for example, the esterification reaction is performed at a temperature of 120 ° C. to 240 ° C., preferably 150 ° C. to 240 ° C., a reaction time of 1 hour or more, preferably 1 to 10 hours, under an inert dry gas atmosphere, at normal pressure. Just do it. Subsequent polymerization reaction is carried out at a temperature of 150 ° C. to 240 ° C., preferably 180 ° C. to 240 ° C., a reaction time of 1 hour or more, preferably 2 to 15 hours, the pressure is gradually reduced from normal pressure, and finally 10 mmHg or less. Preferably, it may be performed at 2 mmHg or less.

  The aliphatic polyester (C) obtained by the polycondensation reaction can be granulated by a known method. For example, there is a method in which a polymer is extracted in the form of a strand from the bottom of a polycondensation reaction tank, cooled with water, or after water cooling, and then cut with a cutter to form pellets or chips of a predetermined shape. In addition, the above-mentioned various additives such as slip agent, filler, plasticizer, antistatic agent, light stabilizer, heat stabilizer, ultraviolet absorber and the like are added to the molten aliphatic polyester (C). You may granulate after adding in the range by which the characteristic of a composition is not impaired.

<Method for producing polyester resin composition>
As a method of mixing the aliphatic aromatic polyester (A), the aliphatic polyester (B) and the aliphatic polyester (C) obtained as described above, for example, a dry blending method using a blender or a mixer Examples of the method include melt mixing using an extruder, and a method of extruding a strand by melt mixing using a screw extruder and pelletizing is generally suitable. For example, after dry blending a predetermined amount of the aliphatic aromatic polyester (A), aliphatic polyester (B) and aliphatic polyester (C), it is supplied into the extruder cylinder by a screw from a hopper and melt plasticized, A method is applied in which a fixed residence time is passed while moving in a cylinder under shear of a screw or a kneading disk, and then extruded into a strand shape through a nozzle and formed into chips after cooling or before cooling with a strand cutter. In this case, the type of the extruder is preferably a biaxial kneading extruder with a vent, and may be used alone or in combination of two or more.
Moreover, as a method of adding the above-mentioned various additives, as described above, the additive is added to at least one of the aliphatic aromatic polyester (A), the aliphatic polyester (B) or the aliphatic polyester (C) in advance. A method of adding a predetermined amount of the above, a method of adding a predetermined amount of the above-mentioned additive at the time of the dry blend, the aliphatic aromatic polyester (A), the aliphatic polyester (B) or the aliphatic polyester (C) in advance Examples thereof include a method of adding a high concentration of the above additive to a master batch and blending a necessary amount of the master batch so that the additive becomes a predetermined amount during the dry blending.

In the present invention, a preferable set temperature of the extruder cylinder used in the production of the composition and various moldings will be described. The temperature setting part of the extruder is provided with a plurality of heaters at the intermediate part from the raw material inlet (hopper) to the outlet (die) coming out as a composition or a molded product. As for the cylinder temperature setting, it is preferable that the inlet side set temperature is 100 ° C to 230 ° C, the intermediate set temperature is 100 ° C to 290 ° C, and the outlet side set temperature is 180 ° C to 280 ° C. When the set temperature is lower than the above range, the polyester resin becomes unmelted, the resin pressure increases, and the extruder motor load may become excessive. On the other hand, when the set temperature is high, the polyester resin may be deteriorated, resulting in an increase in MFR of the resulting composition, or the burnt resin may be mixed as a foreign substance, and the cause of coloring or inflation moldability may be deteriorated.
The extruder set temperature is appropriately adjusted within the above range depending on the copolymer composition, molecular weight, etc. of the aliphatic aromatic polyester (A), aliphatic polyester (B) and aliphatic polyester (C). The size of the extruder is not particularly limited, but the screw diameter is preferably 20 mm to 90 mm, and L / D is preferably about 20 to 40.

<Properties of polyester resin composition>
The polyester resin composition of the present invention has the following properties and is suitable for various molding methods, particularly suitable for inflation molding and T-die molding, and also suitable for stretch molding.
The melt flow rate (MFR) of the polyester resin composition of the present invention is usually 0.1 g / 10 min or more and usually 100 g / 10 min or less when measured at 190 ° C. and a load of 2.16 kg. From the viewpoint of moldability and mechanical strength, it is preferably 50 g / 10 min or less, particularly preferably 30 g / 10 min or less. In particular, it is preferably 1.0 g / 10 min or more and 15 g / 10 min or less for use in extrusion molding with a T die.

The polyester resin composition of the present invention has a melting point of preferably 70 ° C. or higher, more preferably 75 ° C. or higher, preferably 190 ° C. or lower, more preferably 150 ° C. or lower, particularly preferably from the viewpoint of moldability. Is 130 ° C. or lower. When there are a plurality of melting points, at least one melting point is preferably within the above range.
The elastic modulus of the polyester resin composition of the present invention 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 easily occur in the moldability and bag-making property, and when the elastic modulus is 500 MPa or more, it is difficult to obtain the effect of improving the tear strength and impact strength. The method for adjusting the melting point and elastic modulus of the aliphatic aromatic polyester (A) is not particularly limited. For example, the type of copolymerization component other than succinic acid can be selected, or the copolymerization ratio of each can be adjusted. It is possible to adjust by combining them.

3. Film-shaped molded product The polyester resin composition of the present invention can be molded into a film by various molding methods applied to general-purpose plastics. In particular, when the molding is performed by extrusion molding or inflation molding, the effect of the present invention is remarkably exhibited. More specifically, for example, a method of cooling and solidifying a film, sheet or cylinder extruded to a predetermined thickness from a T die, I die or round die with a cooling roll, water, compressed air, etc. Is mentioned. Under the present circumstances, it is also possible to set it as the laminated | multilayer film which laminated | stacked several types of compositions in the range which does not inhibit the effect of this invention.

<Molding method>
In the inflation molding using the polyester resin composition of the present invention, normal known conditions can be adopted as conditions such as bubble internal pressure, heating temperature, bubble diameter, cooling rate, take-up rate and the like. As the molding conditions, for example, the tear strength of the film can be adjusted by setting the blow ratio to 1.1 to 10 times, preferably 2 to 5 times. Further, the suitability for inflation molding is determined by visual observation of bubble stability, frost line height, etc., and the bubble is preferably as stable as it does not shake, and the shape of the bubble is preferably symmetrical. The frost line height is preferably not too high. When the frost line is too high, it indicates that the tube-shaped film is difficult to solidify, and the film is blocked, and the mouth opening may be deteriorated. If the frost line is too low, the air ring or the die may be in contact with the bubbles and may not be molded. Therefore, the frost line needs to have a height suitable for the apparatus, raw materials used, and processing conditions.
The lower limit of the resin temperature in the die is usually 130 ° C. so that the melt viscosity does not become too high and the amount of extrusion per motive power of the extruder is appropriate. On the other hand, a resin degradation product adheres to the die. The upper limit is usually 310 ° C. so as not to be mixed into the polyester. The resin temperature in the die is preferably 140 to 260 ° C, more preferably 170 to 200 ° C.

  In the present invention, the film obtained by inflation molding may have a single layer structure or a laminated structure. The thickness of the film by inflation molding is usually 6 to 100 μm, preferably 10 to 50 μm.

In the T-die molding using the polyester resin composition of the present invention, the lower limit of the resin temperature in the die is usually 140 ° C. so that the melt viscosity does not become too high and the extrusion amount per power of the extruder is appropriate. On the other hand, the upper limit is usually 310 ° C. so as not to be mixed into the polyester obtained by adhering a deteriorated resin to the die. The resin temperature in the die is preferably 150 to 295 ° C, more preferably 160 to 280 ° C. Further, it is desirable to cool the discharged molten resin quickly so as not to proceed with crystallization, and it is usually desirable to cool it with an electrostatic contact type or touch roll type casting roll. In this case, the surface temperature of the casting roll is usually 15 to 70 ° C, preferably 20 to 60 ° C. Moreover, when the thickness of the sheet is 1 mm or more, it is desirable to use a multistage cooling roll. As other molding conditions, normal known conditions can be adopted.

Thereafter, the film-like molded body obtained by the inflation method or the T-die method may be uniaxially or biaxially stretched by a roll method, a tenter method, a tubular method, or the like. When extending | stretching, extending | stretching temperature is normally in the range of 30 to 110 degreeC, and a draw ratio is performed in the range of 0.6 to 10 times in the vertical and horizontal directions, respectively. 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 on a heat roll, or the like.
The film-like molded body obtained by the inflation method or the T-die method may then be laminated with another substrate. As the lamination method, a usual known method can be adopted. For example, there are a dry lamination method, a non-solvent lamination method, and a thermal lamination method.

<Properties of molded film>
(Tear strength)
The film obtained from the polyester resin composition obtained by the above method has the following properties. The tear strength of an inflation film is measured by the Elmendorf method specified in JIS K7128-2 (1998), but in practice, tearing starting from a notch formed at the cut end of a film molded product tends to be a problem. Therefore, the value in the MD direction is important. From the viewpoint of practicality, the MD direction is usually 5 N / mm or more, preferably 25 N / mm or more, more preferably 45 N / mm or more. On the other hand, the TD direction is not particularly limited, but is usually 5 N / mm or more, preferably 20 N / mm or more.

(Biodegradation rate)
From the viewpoint of durability, the biodegradability rate of the film of the present invention is preferably 12% or more, and more preferably 20% or more, as the lower limit of the tensile fracture stress retention rate on the seventh day. On the other hand, the upper limit is preferably 95% or less, and more preferably 80% or less, from the viewpoint of rapid decomposition after being buried in the soil. Further, the tensile fracture strain on the seventh day is preferably 15% or more, and more preferably 20% or more, from the viewpoint of durability. On the other hand, 95% or less is preferable and 80% or less is more preferable from the viewpoint of prompt decomposition after being buried in the soil.

<Multi film>
The polyester resin composition of the present invention can be molded and suitably used as a multifilm for agriculture. A known method may be used for forming the multifilm. In the use of the multifilm obtained by molding the resin composition according to the present invention, those having particularly excellent tear strength are suitable and measured by the Elmendorf method. The value in the MD direction is important because tearing starting from the notch that is generated tends to be a problem. From the viewpoint of moldability, the MD direction is usually 5 N / mm or more, preferably 20 N / mm, more preferably 40 N / mm or more. The TD direction is usually 5 N / mm or more, preferably 20 N / mm or more.
Moreover, what is excellent also in the tensile fracture stress is suitable, Preferably it is 20-60 Mpa. The multi-film formed by molding the polyester resin composition of the present invention can prevent the film from tearing and increasing the defective part when laid, and the multi-film can be torn by impact. Can be prevented.
Moreover, what is excellent also in the tensile fracture strain is suitable, Preferably it is 100 to 500%. The multi-film formed by molding the polyester resin composition of the present invention can prevent the film from tearing and increasing the defective part when laid, and the multi-film can be torn by impact. Can be prevented.

In addition, the multifilm formed by molding the polyester resin composition of the present invention has a suppressed decrease in tear strength and impact strength during the use period of the multifilm, and after use, the multifilm can be embedded in the soil as it is. In order to be decomposed and have appropriate biodegradability as a multifilm, the lower limit of the tensile fracture stress retention rate on the seventh day is preferably 12% or more, and more preferably 20% or more. On the other hand, the upper limit is preferably 95% or less, and more preferably 80% or less, from the viewpoint of rapid decomposition after being buried in the soil. Further, the tensile fracture strain on the seventh day is preferably 15% or more, and more preferably 20% or more, from the viewpoint of durability. On the other hand, 95% or less is preferable and 80% or less is more preferable from the viewpoint of prompt decomposition after being buried in the soil.
In addition, when the polyester resin composition of the present invention is molded and used as a multi-film, carbon black or titanium oxide may be added to the polyester resin composition, or the polyester resin composition of the present invention and carbon black or oxidation may be mixed. Titanium may be mixed and molded. The carbon black and titanium oxide are not particularly limited in terms of type and blending amount as long as they provide the necessary light-shielding properties and heat-retaining properties as a multi-film and do not reduce the film strength.

<Compost bag>
A film obtained from the polyester resin composition of the present invention can be molded into a compost bag. A known method can be applied to the bag forming method. For example, it can be molded by heat-sealing the end of a blown tubular body. Here, as described above, a bag obtained from the film of the present invention is particularly excellent in tear strength, and is measured by the Elmendorf method, but the notch generated at the cut edge of the film molded body in the multifilm application of the present invention. The value in the MD direction is important because tearing starting from tended to be a problem. From the viewpoint of moldability, the MD direction is usually 5 N / mm or more, preferably 20 N / mm, more preferably 40 N / mm or more. The TD direction is usually 5 N / mm or more, preferably 20 N / mm or more.
Moreover, what is excellent also in the tensile fracture stress is suitable, Preferably it is 20-60 Mpa. Further, the lower limit of the tensile fracture stress retention rate on the seventh day is preferably 12% or more, and more preferably 20% or more. On the other hand, the upper limit is preferably 95% or less, and more preferably 80% or less, from the viewpoint of rapid decomposition after being buried in the soil. Further, the lower limit of the tensile fracture strain on the 7th day is preferably 15% or more, more preferably 20% or more, from the viewpoint of durability. On the other hand, 95% or less is preferable and 80% or less is more preferable from the viewpoint of prompt decomposition after being buried in the soil.
The compost bag formed by molding the polyester resin composition of the present invention is excellent in tearing strength, so that the tearing of the bag is suppressed, and because it is excellent in impact strength, when opening the bag or filling the bag, It is possible to prevent the bag from tearing due to impact. Further, the compost bag has a property of maintaining mechanical strength during normal storage, and is preferably biodegraded quickly after being buried in the soil. An appropriate amount of various additives such as anti-blocking agents such as slip agents and talc and carbon black may be added to the polyester resin composition of the present invention for molding.

  EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the following description, “part” means “part by mass” unless otherwise specified. Moreover, the property of the laminated body in each Example and a comparative example is measured in the following procedure.

<Evaluation method of polyester resin composition>
(1) Melt flow rate (MFR)
Based on JIS K7210, it measured at 190 degreeC and the load 2.16kg using the melt indexer. The unit is g / 10 minutes.

(2) Acid value The acid value was measured by the following method. 0.5 g of the sample was precisely weighed, put into a test tube containing 25 mL of benzyl alcohol, and heated in a heating bath at 195 ° C. for 9 minutes to dissolve the sample. . After confirming that the sample was completely dissolved and cooled in ice water for 30 to 40 seconds, 2 mL of ethyl alcohol was added. While stirring, a pH electrode was placed in the sample solution, and neutralization titration was performed by potentiometric titration using a benzyl alcohol solution of 0.01N sodium hydroxide (10% methanol solution).
On the other hand, a blank sample in which the sample was not dissolved was prepared, and titration was performed in the same manner as described above to obtain a blank value.
From the titration results, the acid value (AV value: μeq / g) was calculated using the following formula.
In the measurement of potentiometric titration, an automatic titration apparatus (manufactured by Toa DKK Co., Ltd., product name: Autotitrator AUT-50) was used.

A: Measurement titration value (mL)
B: Blank measured value (mL)
F: Potency of benzyl alcohol solution of 0.01N sodium hydroxide W: Sample mass (g)

(3) Melting point A differential scanning calorimeter (manufactured by Seiko Co., Ltd., product name: DSC220) was used for measuring the melting point. About 10 mg of sample is precisely weighed, heated and melted in a nitrogen stream at a flow rate of 40 mL / min, cooled at a rate of 10 ° C./min, and then the melting peak top when the temperature is continuously raised at a rate of 10 ° C./min The temperature was taken as the melting point.

(4) ¹ H-NMR
About 30 mg of the sample was weighed into an NMR sample tube having an outer diameter of 5 mm, and dissolved in 0.75 mL of deuterated chloroform. For this, using a Bruker AVANCE400 nuclear magnetic resonance apparatus, it was analyzed by ¹ H-NMR spectrum at room temperature. The standard of chemical shift was tetramethylsilane (TMS) of 0.00 ppm. The composition ratio of each polymer was calculated. The composition ratio of each polymer was calculated with the total dicarboxylic acid component as 100 mol%.

<Materials used and their properties>
Details of the resins used in the examples are as follows. (1) Aliphatic Aromatic Polyester (i) Production Example 1 Production of polybutylene succinate terephthalate (PBST: Aliphatic Aromatic Polyester (A)) A stirrer, a nitrogen inlet, a heating device, a thermometer and a vacuum port are provided. 1,4 parts in which 45 parts of succinic acid, 107 parts of 1,4-butanediol, 64 parts of dimethyl terephthalate, 0.1 part of malic acid, and 5% by mass of titanium tetrabutyrate were previously dissolved in the reaction vessel. -2.1 parts of butanediol solution and 3.5 parts of 1,4-butanediol solution in which 2% by mass of magnesium acetate tetrahydrate had been dissolved in advance were charged.
Nitrogen gas was introduced into the container while stirring the contents of the container, and the system was placed in a nitrogen atmosphere by vacuum replacement. Next, the temperature was raised to 185 ° C. while stirring the system, and the reaction was carried out at this temperature for 45 minutes to 1 hour. Next, it heated up to 220 degreeC over 1 hour 30 minutes. Thereafter, the temperature was raised to 230 ° C. over 1 hour, the pressure was reduced to 0.07 × 10 ³ Pa or less over 1 hour 30 minutes, and the polymerization was continued while maintaining the heated and reduced pressure state to obtain a predetermined viscosity. Then, the polymerization was terminated, and the polymer was extracted from the reaction vessel in a strand shape, cooled with water, and pelletized with a pelletizer to obtain a pale yellow copolymer.
The physical properties of the resulting aliphatic aromatic polyester (A) were MFR = 2.5 g / 10 min, η _sp /c=2.35, acid value = 33 μeq / g, melting point 130 ° C., and the composition of the resin was carbon The content of an aliphatic dicarboxylic acid unit having a number of 5 or less was 25 mol%, the content of an aromatic dicarboxylic acid unit having 5 to 40 carbon atoms was 25 mol%, and the content of a diol unit was 50 mol%.

(Ii) Polybutylene adipate terephthalate (PBAT: comparative resin)
Product name: Ecoflex manufactured by BASF Corporation was used. The resin has MFR = 4.5 g / 10 min, η _sp /c=1.89, acid value = 22 μeq / g, melting point 120 ° C., ¹ H-NMR result, content of aliphatic dicarboxylic acid unit Was 27 mol%, the content of aromatic dicarboxylic acid units was 23 mol%, and the content of diol units was 50 mol%.

(2) Aliphatic polyester (B)
(I) Production Example 2 Preparation of Polyester Polycondensation Catalyst 100 parts by mass of magnesium acetate tetrahydrate was added to a glass eggplant-shaped flask equipped with a stirrer, and 400 parts by mass of absolute ethanol (purity 99% by mass or more). Was added. Further, 65.3 parts by mass of ethyl acid phosphate (mixing weight ratio of monoester and diester was 45:55) was added, and the mixture was stirred at 23 ° C. After confirming that magnesium acetate was completely dissolved after 15 minutes, 122.2 parts by mass of tetra-n-butyl titanate was added. Stirring was further continued for 10 minutes to obtain a uniform mixed solution. This mixed solution was transferred to an eggplant-shaped flask and concentrated under reduced pressure by an evaporator in an oil bath at 60 ° C. After 1 hour, most of the ethanol was distilled off, leaving a translucent viscous liquid. The temperature of the oil bath was further raised to 80 ° C., and further concentration was performed under a reduced pressure of 667 Pa (5 Torr). The viscous liquid gradually changed from the surface to a powder form, and was completely powdered after 2 hours. Further, a powdery catalyst was dissolved in 1,4-butanediol and prepared so as to be 10,000 ppm as a titanium atom.

(Ii) Production Example 3 Production of Polybutylene Succinate Adipate (PBSA: Aliphatic Polyester (B)) In Production Example 3, 100 parts by mass of succinic acid, 43.6 parts by mass of adipic acid, 155 parts by mass of 1,4-butanediol Polymerization was carried out in the same manner as in Production Example 3 except that 0.382 parts by mass of malic acid was used to obtain a polyester resin.
The obtained polyester resin had a melting point of 83.8 ° C., an MFR value of 3.2 g / 10 min, and an aliphatic dicarboxylic acid having 5 or more carbon atoms in the dicarboxylic acid unit constituting the polyester resin was 48 mol%. It was.

(3) Aliphatic polyester (C)
(I) Polylactic acid Mitsui Chemicals, product name: Lacia H440 was used. The resin had MFR = 3.0 g / 10 min, η _sp /c=2.3, acid value = 30 μeq / g, melting point 153 ° C., and was composed of 100 mol% lactic acid.

(4) Additive (i) Additive 1: Erucic acid amide (slip agent)
Nippon Seika Co., Ltd. product name: L agent was used.

<Evaluation method of film>
An inflation film with a blower ratio of 2.65, discharge rate of 10 kg / h, constant air blow was molded into an inflation film with a 40 mm extruder and a round die with a diameter of 60 mm, and used for various evaluations. did.

(1) Film thickness Using the film obtained by the above inflation molding, measurement was performed using a digital micrometer. The measurement surface has a planar shape with a diameter of 5 mm. The unit is expressed in μm.

(2) Elmendorf Tear Strength Test Digital Elmendorf Tear Tester (Product name: SA manufactured by Toyo Seiki Seisakusho Co., Ltd.) is used in accordance with JIS K7128-2 (1998) using the film obtained by the above-described inflation molding. -WP). The unit is expressed in N / mm.

(3) Tensile test The film obtained by the above inflation molding is punched into a No. 2 dumbbell-shaped sample described in JIS K6251 (1993) in both MD and TD directions, and subjected to a tensile test according to JIS K7127 (1999). Measurements of fracture stress and tensile fracture strain were obtained. One test piece was used, the tensile speed was 500 mm / min, and the average of three measurements was used as the test result. Units are expressed in MPa and%, respectively.

(4) Soil burial test evaluation Using the film obtained by the above inflation molding, biodegradability evaluation was performed as follows.
Put the soil of Mie prefecture field (water that has been screened with a 4 mm sieve) into a polyethylene container (22 cm × 16 cm × 5.5 cm), and place the film in JIS K 6251 (1993). ). Three samples and four types of test pieces (12 pieces in total) were arranged in a single container so as not to overlap each other, and two pieces each covered with soil having a height of about 1 cm were prepared. Each sample was placed in a constant temperature and humidity chamber of 40 ° C. and 90% RH, and samples were taken out after 4 and 7 days from the start of the test, respectively, and the soil adhering with brushes was carefully removed, and sample 3 was not subjected to the soil burial test. The tensile test of the above (3) was carried out in an environment of 23 ° C. and 50 RH together with the sheets, and the test results of tensile fracture stress and tensile fracture strain were obtained. The test results of the tensile failure stress and tensile fracture strain of the samples that were not subjected to the soil burial test were calculated as 100%, and the test results of the tensile fracture stress and tensile fracture strain of each sample were calculated in percentage after 4 and 7 days from the start of the test. The tensile fracture stress retention rate (%) was taken as the tensile fracture strain retention rate (%).

Example 1
20 parts by mass of the resin (PBST) produced in Production Example 1 as the aliphatic aromatic polyester (A), 70 parts by mass of the resin (PBSA) produced in Production Example 3 as the aliphatic polyester (B), C) 10 parts by mass of polylactic acid and 0.1 parts by mass of erucic acid amide (L agent: slip agent) as an additive were dry blended, and the mixture was mixed into a twin-screw kneader (manufactured by Nippon Steel Works; TEX30) The cylinder set temperature was C1: 100 ° C., C2: 150 ° C., C3 to C15: 180 ° C., die head: 180 ° C., screw rotation speed 200 rpm, and vacuum venting was performed with the cylinder (C12). The screw was rotated in the same direction, extruded in a strand at a discharge rate of 20 kg / h, cooled with water, and then cut into pellets with a pelletizer to obtain a resin composition.
Next, with a single-layer inflation film molding machine (manufactured by Misuzu Erie, product name: MK-40, extruder cylinder diameter = 40 mm, round die diameter = 60 mm, die lip gap width = 1 mm, equipped with dual lip type air ring) The cylinder set temperature is C1: 150 ° C, C2: 170 ° C, C3: 190 ° C, the die set temperature is 190 ° C, the blow-up ratio is 2.65, the discharge rate is 10kg / h, the air blow is constant, and the film thickness is 20μ. A film was created. The Elmendorf tear strength of the obtained film is shown in Table 1. The inflation moldability was good, and the appearance of the obtained film was also good. The tear strength was also high.

Example 2
In Example 1, except that the blending amount of the aliphatic aromatic polyester (A), the blending amount of the aliphatic polyester (B), and the blending amount of the aliphatic polyester (C) were changed as shown in Table 1. Evaluation was performed in the same manner as in Example 1. The film obtained from the resin composition of Example 2 has the same tear strength as that of Example 1, and has a high tensile fracture stress retention rate and tensile fracture strain retention rate. Therefore, the aliphatic aromatic polyester (A) It can be seen that the biodegradation rate changes when the blending amount of A and the blending amount of the aliphatic polyester (B) change.

Comparative Examples 1 and 2
In Example 1 and Example 2, it is the same as that of Example 1 and 2 except having changed into the comparison resin (PBAT) instead of resin (PBST) manufactured by manufacture example 1 as an aliphatic aromatic polyester (A). Was evaluated. The tear strength values of the obtained films were almost the same as in Examples 1 and 2, but the tensile fracture stress retention rate and tensile fracture strain retention rate were particularly on the 7th day compared to Example 1 and Example 2. From the decrease, it can be seen that the biodegradation rate could not be suppressed.

Comparative Example 3
Comparative Example 1 except that the blending amount of the aliphatic polyester (C) was changed to 0 part by mass (not blended) and the blending amount of the aliphatic aromatic polyester (A) was changed to 30 parts by mass in Comparative Example 1. Evaluation was performed in the same manner as above. The tear strength value of the obtained film was lower than that of Comparative Examples 1 and 2, and was slightly inferior to practicality. Moreover, since the tensile fracture stress retention rate and the tensile fracture strain retention rate are also lower than those of Comparative Examples 1 and 2, it can be seen that the biodegradation rate could not be suppressed.
Table 1 shows the results of the tear strength, tensile fracture stress retention, and tensile fracture strain retention of the examples and comparative examples.

  As can be seen from Table 1, Example 1 and Example 2 using PBST having a succinic acid component as the aliphatic aromatic polyester (A) are Comparative Examples 1 using PBAT as a comparative resin having no succinic acid component. And with respect to Comparative Example 2, the tensile fracture stress retention rate and tensile fracture strain retention rate after 7 days were high, and the biodegradation rate was suppressed. Moreover, compared with the comparative example 3 which did not use aliphatic polyester (C), the tear strength was high and the practicality as a film was high. Moreover, by controlling the blending amount of the aliphatic aromatic polyester (A) and the blending amount of the aliphatic polyester (B), the biodegradation rate can be changed and adjusted to a biodegradation rate suitable for the intended use.

  The resin composition of the present invention is excellent in film moldability, and the film formed by molding the polyester resin composition of the present invention has high tear strength, and can be controlled to a biodegradation rate suitable for its use. It is particularly useful in the field of agricultural materials such as forming multi-films and compost bags.

Claims (8)

Aliphatic aromatic polyester (A) having a structural unit derived from an aliphatic dicarboxylic acid, a structural unit derived from an aromatic dicarboxylic acid, and a structural unit derived from an aliphatic diol, and a structural unit derived from an aliphatic dicarboxylic acid and an aliphatic diol A polyester resin composition comprising an aliphatic polyester (B) having a structural unit derived from and an aliphatic polyester (C) having a structural unit derived from an oxycarboxylic acid as a main component, wherein the aliphatic aroma family polyester (a) comprises structural units derived from succinic acid, the aliphatic polyester (B) is viewed contains a structural unit derived from adipic acid, said aliphatic-aromatic polyester (a) and the aliphatic polyester (B) And the ratio of the aliphatic polyester (B) to the total of the aliphatic polyester (C) is 50% by mass or more and 80% by mass or less, relative to the total Polyester resin composition, wherein the ratio of the aliphatic polyester (C) is 30 wt% or less than 1 wt%.   The polyester resin composition according to claim 1, wherein the aliphatic polyester (C) is polylactic acid.   The polyester resin composition according to claim 1 or 2, wherein the aliphatic diol is 1,4-butanediol. The polyester resin composition according to any one of claims 1 to 3 , wherein the aliphatic polyester (B) further has a structural unit derived from succinic acid. Furthermore, the polyester resin composition of any one of Claims 1-4 containing a slip agent. Furthermore, the polyester resin composition of any one of Claims 1-5 containing a talc. Furthermore, the polyester resin composition of any one of Claims 1-6 containing a carbodiimide. Film obtained by molding the polyester resin composition according to any one of claims 1-7.