JP5601017B2 - Biodegradable resin composition and method for producing the same - Google Patents

Description

  The present invention relates to a resin composition containing starch, a method for producing the resin, a molded article using the resin, and a film using the resin. Specifically, the present invention relates to a resin composition excellent in elastic modulus and tear strength and excellent in biodegradability, a production method thereof, a molded article using the resin, and a film using the resin.

  In modern society, various materials such as paper, plastic, and aluminum foil are used for various foods, medicines, miscellaneous products such as liquids and granules, solid packaging materials, agricultural materials, and building materials. Is used. Among them, plastics are excellent in strength, water resistance, moldability, transparency, cost, etc., and are therefore used in a wide range of applications as molded articles such as bags and containers. Currently, plastics widely used for applications such as bags and containers include polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. However, molded articles made of the above-mentioned plastics do not biodegrade or hydrolyze in the natural environment, or the degradation rate is extremely slow, so when they are buried after use, they remain in the soil or are dumped. If this happens, the scenery may be damaged. Moreover, even when incinerated, there are problems such as generating harmful gases and damaging the incinerator.

  Biodegradable resins have been attracting attention as environmentally friendly plastics that solve these problems. Since the film formed by molding the biodegradable resin is decomposed in the soil by embedding in the soil after use, it is possible to prevent global warming and soil and air pollution. In particular, since a film in which starch is combined with a biodegradable resin can maintain biodegradability and improve the mechanical strength of the film, various studies have been made (for example, see Patent Document 1).

JP 2008-013602 A

  When applying a film in which starch is combined with biodegradable resin to agricultural multi-films, etc., the biodegradation rate of starch is high, so the strength of the film decreases during the growing period of crops, making it unsuitable for practical use. is there. Therefore, generally reducing the compounding quantity of the starch in a film is performed. As a method for adjusting a resin composition with a reduced amount of starch, a method (1) in which starch and thermoplastic resin are collectively charged into an extruder and kneaded to obtain a predetermined composition, a starch and starch plasticizer A method (2) in which only a composition obtained by kneading only into an extruder and kneaded and a thermoplastic resin is again charged into the extruder and kneaded to obtain a predetermined composition is generally performed.

  However, in the method (1), particularly when the amount of starch in the composition is small, the starch plasticizer may not sufficiently permeate into the starch during the kneading process, and the starch particles are destroyed and flow at a high temperature. (Hereinafter, this is sometimes referred to as gelatinization or thermoplasticization), and the dispersion diameter of starch in the composition tends to increase, and the film is formed. The mechanical properties of the product are likely to deteriorate. On the other hand, in the method (2), the starch is sufficiently thermoplastic (gelatinization), but depending on the type of thermoplastic resin used, the thermoplastic starch and the thermoplastic Due to the difference in the melt viscosity of the resin, the dispersion diameter of the starch in the composition becomes large, and there is a technical problem that the mechanical properties of the molded product are liable to decrease as in (1).

Therefore, a starch composite degradable resin composition having good starch dispersibility and a good balance between mechanical strength and biodegradability and a molded product thereof are desired.
This invention is made | formed in view of the said subject, and makes it a subject to provide the biodegradable resin composition and its manufacturing method with which the mechanical physical property, especially the tensile elasticity modulus and tear strength were improved.

[1]
30% by weight or more and 90% by weight or less of aliphatic polyester resin (A) , 2% by weight or more and less than 30% by weight of resin (A) different from aromatic-aliphatic polyester resin (B), 5% by weight or more and 30% by weight A method for producing a starch-containing resin composition (Y) comprising the following starch (C) and an organic compound (D) containing 1 to 10% by weight of a hydroxyl group,
(I) Aliphatic polyester resin (A), aromatic-aliphatic polyester resin (B) different from resin (A), starch (C) of 30 wt% to 60 wt%, and 3 wt% to 20 wt% A step of obtaining a starch-containing resin composition (X) by melt-kneading the following organic compound (D) containing a hydroxyl group;
And (ii) the starch-containing resin composition (X), and different aromatic aliphatic polyester resin (A) and the resin (A) - a step of dilution with at least one resin selected from the aliphatic polyester resin (B) ,
The manufacturing method of the starch-containing resin composition (Y) which has.
[2]
[1] A method for producing a starch-containing resin composition (Y) according to [1], wherein (i) a twin-screw extruder having a main raw material supply part and a secondary raw material supply part is used, from the main raw material supply part An aromatic-aliphatic polyester resin (B) different from the resin (A), starch (C), and an organic compound (D) containing a hydroxyl group are supplied, and the aliphatic polyester resin (A) is added to the secondary polyester resin (A). A step of obtaining a starch-containing resin composition (X) in which the content of starch (C) is 30 wt% or more and 60 wt% or less by supplying from the raw material supply section and kneading,
And (ii) mixing the resin composition (X) with the aliphatic polyester resin (A) and an aromatic-aliphatic polyester resin (B) different from the resin (A). Manufacturing method of thing (Y).
[3]
In [1] or [ 2 ], the ratio of the aromatic-aliphatic polyester resin (B) different from the resin (A) in the step (i) to the starch (C) is 20 wt% or more and 70 wt% or less. The manufacturing method of the starch-containing resin composition (Y) of description.
[ 4 ]
The starch-containing resin composition according to any one of [1] to [ 3 ], wherein the aliphatic polyester resin (A) is at least one selected from polybutylene succinate and polybutylene succinate adipate ( Y) production method.

  According to the present invention, it is possible to provide a starch-containing resin composition having excellent physical properties, particularly excellent mechanical properties such as tear strength and biodegradability. This resin composition is excellent in dispersibility of each component in the composition and also has good moldability. For this reason, the molded product obtained from the biodegradable resin composition, particularly a film, is used not only for general uses such as garbage bags and shopping bags but also for agricultural films that require a certain level of biodegradability. Also, it can be suitably used.

It is the schematic of the twin screw extruder preferably used for manufacture of the biodegradable resin composition of this invention.

  The present invention relates to a method for producing a starch-containing resin composition, a specific resin composition produced by the production method, and a molded article and a film comprising the resin composition, wherein the starch-containing composition is a specific quantity ratio. A starch particle having a specific particle diameter, comprising a biodegradable resin (A), a thermoplastic resin (B) other than the biodegradable resin (A), starch (C), and an organic compound (D) having a hydroxyl group. Is.

Hereinafter, each component, a manufacturing method, etc. are demonstrated in detail.
In the present specification, a resin composition containing a specific resin as a component may be called with the name of the resin as the main component. Here, the “main component” usually means the most abundant component constituting the composition, preferably 50% by weight or more, more preferably 70% by weight or more, particularly preferably 90% by weight or more. It shall be said. For example, “polybutylene succinate-based resin” refers to a resin composition containing a polybutylene succinate-based resin as a main component.

Further, in this specification, the term “polymer” refers to a polymer composed of a single type of repeating structural unit (so-called “homopolymer”) and a polymer composed of a plurality of types of repeating structural units (so-called “polymer”). It is used as a concept including “copolymer”).
In the following description, a partial structural unit of a polymer derived from a certain monomer is represented by adding the word “unit” to the name of the monomer. For example, the partial structural unit derived from dicarboxylic acid is represented by the name “dicarboxylic acid unit”.

  Moreover, the monomer which gives the same partial structural unit is named generically by the name which replaced the "unit" of the name of the partial structural unit with "component." For example, monomers such as aromatic dicarboxylic acids and aromatic dicarboxylic acid diesters form aromatic dicarboxylic acid units, even if the reaction in the process of forming the polymer is different. Therefore, these aromatic dicarboxylic acids and aromatic dicarboxylic acid diesters are collectively referred to as “aromatic dicarboxylic acid component”.

<Resin having biodegradability (A)>
The biodegradable resin (A) in the present invention is not limited as long as it is a biodegradable resin, and any known biodegradable resin can be used as long as the effects of the present invention are not significantly impaired. it can. More specifically preferred are polycaprolactone, polybutylene succinate, polybutylene succinate adipate, polyethylene succinate, polyethylene adipate, polybutylene adipate, polyhydroxybutyrate, polyhydroxyvalerate, polylactic acid, polyglycolic acid Aliphatic polyesters and derivatives thereof, alicyclic polyesters and derivatives thereof such as polycyclohexylene dimethyl adipate, fatty acid ester copolymers such as hydroxybutyrate-hydroxyvalerate copolymer, poly (butylene adipate / terephthalate), poly And aromatic-aliphatic polyesters such as (ethylene terephthalate / succinate). As the resin (A), a plurality of resins may be mixed and used. However, as described in the section of the thermoplastic resin (B), the starch-containing resin composition (X) and the starch-containing resin composition (Y) according to the present invention are different from the resin (A). Use of a biodegradable resin as the thermoplastic resin (B) is not prevented. That is, when a plurality of biodegradable resins are used, a thermoplastic resin that satisfies the weight ratio in the composition defined by the thermoplastic resin (B) is understood as the thermoplastic resin (B). Does not prevent it from being done.

  In the present invention, these biodegradable resins may be produced by any known production method, but those derived from biomass resources are preferred. Although these biomass resources are not particularly limited, they are induced to a carbon source through known pretreatment and saccharification processes such as chemical treatment with acids and alkalis, biological treatment using microorganisms, physical treatment, and the like. Is used. Among these biodegradable resins, aliphatic polyesters and derivatives thereof, aromatic-aliphatic polyesters and derivatives thereof are more preferable, and aliphatic polyesters and derivatives thereof are particularly preferable.

  The aliphatic polyesters shown above include aliphatic dicarboxylic acid units such as aliphatic polyesters, polybutylene succinates, polybutylene succinate adipates and aliphatic diol units such as polycaprolactone and polylactic acid. The main constituent unit is composed of an aliphatic polyester, and among them, the main constituent unit is preferably an aliphatic diol unit and an aliphatic dicarboxylic acid unit, which will be described in detail below.

  The aliphatic polyester mainly composed of an aliphatic diol unit and an aliphatic dicarboxylic acid unit is a chain aliphatic and / or alicyclic diol unit represented by the following formula (1), and the following formula (2). It consists of the chain | strand-shaped aliphatic and / or alicyclic dicarboxylic acid unit represented by these.

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

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

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

The aliphatic diol component giving the diol unit of the formula (1) is not particularly limited, but an aliphatic diol component having 2 to 10 carbon atoms is preferable, and an aliphatic diol component having 4 to 6 carbon atoms is particularly preferable. Specific examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like.
The aliphatic dicarboxylic acid component giving the dicarboxylic acid unit of the formula (2) is not particularly limited, but an aliphatic dicarboxylic acid component having 2 to 10 carbon atoms is preferable, and an aliphatic dicarboxylic acid component having 4 to 8 carbon atoms is particularly preferable. preferable. Specific examples include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like.

  1,4-butanediol is particularly preferred as the aliphatic diol component giving the diol unit of the formula (1), and succinic acid or adipine as the aliphatic dicarboxylic acid component giving the dicarboxylic acid unit of the formula (2) Acid is particularly preferred. The aliphatic polyester resin used in the present invention is particularly preferably a polybutylene succinate resin and / or a polybutylene succinate adipate resin.

  In addition, aliphatic oxycarboxylic acid units may be contained in an aliphatic polyester resin mainly composed of an aliphatic diol and an aliphatic dicarboxylic acid. Specific examples of the aliphatic oxycarboxylic acid that gives an aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2- Examples thereof include hydroxy-3-methylbutyric acid and 2-hydroxyisocaproic acid. These lower alkyl esters and intramolecular esters may also be used. In addition, when optical isomers exist in these, any of D-form, L-form, and racemate may be used, and the form may be any of solid, liquid, or aqueous solution. Among these, lactic acid or glycolic acid is preferable. These aliphatic oxycarboxylic acids can be used alone or as a mixture of two or more.

The amount of the aliphatic oxycarboxylic acid unit is usually 0 mol% or more, preferably 0.01 mol% or more, and the upper limit is usually 30 mol or less, among all the components constituting the aliphatic polyester resin. The mol% or less, preferably 20 mol% or less.
In addition, the aliphatic polyester-based resin is a compound having three or more functions, such as “aliphatic or alicyclic polyhydric alcohol”, “aliphatic or alicyclic polycarboxylic acid or its anhydride”, “aliphatic polyhydric acid”. It is preferable that at least one of “valent oxycarboxylic acids” is copolymerized since the melt viscosity of the resulting aliphatic polyester resin can be increased.

Specific examples of the trifunctional aliphatic or alicyclic polyhydric alcohol include trimethylolpropane and glycerin. Specific examples of the tetrafunctional or higher aliphatic or alicyclic polyhydric alcohol include pentaerythritol. It is done.
Specific examples of the trifunctional aliphatic or alicyclic polycarboxylic acid or its anhydride include propanetricarboxylic acid or its anhydride, and a tetrafunctional aliphatic or alicyclic polycarboxylic acid or its anhydride. Specific examples of the product include cyclopentanetetracarboxylic acid or its anhydride.

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

The amount of such a tri- or higher functional compound is usually 0.0001 mol% or more, preferably 0.01 mol%, based on the whole monomer constituting the aliphatic polyester resin (100 mol%). The upper limit is usually 1 mol% or less, preferably 0.5 mol% or less.
There is no restriction | limiting in the manufacturing method of aliphatic polyester-type resin, unless the effect of this invention is impaired remarkably, It can manufacture by any well-known method. For example, it can be produced by a melt polymerization method in which an esterification reaction between a dicarboxylic acid component and a diol component is performed, followed by a polycondensation reaction under reduced pressure, a solution heating dehydration condensation method using an organic solvent, or the like. Among these, from the viewpoint of economy and simplicity of the production process, a melt polymerization method carried out in the absence of a solvent is preferable.

  When manufacturing an aliphatic polyester-type resin, the additive may be added. Examples of the additive include carbonate compounds and polyfunctional isocyanate compounds. By mixing these compounds, the structure includes a carbonate bond (hereinafter, this bond portion is particularly referred to as “carbonate bond unit”) and a urethane bond (hereinafter, this bond portion is particularly referred to as “urethane bond unit”). Can be produced. In addition, the carbon chain of the aliphatic polyester resin can be extended.

The amount of the carbonate bond unit relative to all the structural units of the aliphatic polyester resin is usually 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, and there is no lower limit and no mixing is performed. May be.
Specific examples of the carbonate compound include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, and dicyclohexyl carbonate. Can be given. In addition, carbonate compounds composed of the same or different hydroxy compounds derived from hydroxy compounds such as phenols and alcohols can be used.

On the other hand, the amount of urethane bond units relative to all structural units of the aliphatic polyester resin is usually 5 mol% or less, preferably 3 mol% or less, more preferably 1 mol% or less, and there is no lower limit. You don't have to.
Specific examples of the polyfunctional isocyanate compound include 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, and xylylene. Examples thereof include known diisocyanates such as diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate, and trifunctional or higher functional isocyanate compounds.

As examples of other additives, dioxazoline, silicate ester, and the like can be used as a chain extender.
Specific examples of the silicate ester include tetramethoxysilane, dimethoxydiphenylsilane, dimethoxydimethylsilane, and diphenyldihydroxylane. The content of the silicate ester is not limited from the viewpoint of environmental protection and safety. However, since the operation may become complicated and the polymerization rate may be affected, it is preferable that the amount used is small. Specifically, it is preferably 0.1 mol% or less, more preferably 10 ⁻⁵ mol% or less, based on all structural units constituting the aliphatic polyester resin.

In order to increase the melt tension, a small amount of peroxide may be mixed as long as a compound having low toxicity is mixed. Moreover, you may seal a polyester resin terminal group with a carbodiimide compound, an epoxy compound, monofunctional alcohol, or carboxylic acid.
The aliphatic polyester-based resin may be derived from biomass resources. There is no restriction | limiting in the kind of biomass resource, or its manufacturing method, unless the effect of this invention is impaired remarkably. For example, biomass resources obtained by induction to a carbon source through any known pretreatment / saccharification process such as chemical treatment of acids and alkalis, biological treatment using microorganisms, and physical treatment Can also be used.

  The preferred melt flow index (MFI) of the aliphatic polyester resin is usually 0.1 g / 10 min or more, and usually 100 g / 10 min or less, preferably 50 g / 10 min when measured at 190 ° C. and 2.16 kg. Hereinafter, it is more preferably 30 g / 10 min or less. Moreover, when measured at 220 ° C. and 2.16 kg, it is usually 0.1 g / 10 min or more and 150 g / 10 min or less, preferably 100 g / 10 min or less, more preferably 70 g / 10 min or less. Here, the MFI is a value at 190 ° C., a load of 2.16 kg, or 220 ° C. and a load of 2.16 kg, measured according to the thermoplastic flow test method specified in JIS K7210.

The preferred weight average molecular weight of the aliphatic polyester resin is usually 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and usually 1,000,000 or less, preferably 800,000. Hereinafter, it is more preferably 600,000 or less. If it is out of this range, it tends to be difficult to perform various molding processes.
The melting point of the aliphatic polyester resin is usually 60 ° C. or higher, preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and usually 250 ° C. or lower, preferably 240 ° C. or lower, more preferably 220 ° C. or lower. is there. The melting point can be measured, for example, by differential scanning calorimetry (DSC). Specifically, using a DSC7 differential scanning calorimeter manufactured by Perkin Elmer, Inc., the sample was heated from room temperature to 230 ° C. under the condition of 80 ° C./min, held at the same temperature for 10 minutes, and then −10 The temperature is lowered to 40 ° C. at a temperature of 40 ° C./minute, held at the same temperature for 3 minutes, and then the melting point can be the peak temperature when melted under a temperature rising condition of 10 ° C./minute.

  When the aliphatic polyester-based resin contains a large amount of low molecular weight oligomer, when the biodegradable resin composition containing the resin is molded, the low molecular weight oligomer contained is ejected on the surface of the molded body with time after molding, and the appearance is impaired. Sometimes. Therefore, the upper limit of the amount of the low molecular weight oligomer in the aliphatic polyester resin is usually 30000 ppm or less, preferably 15000 ppm or less, more preferably 12000 ppm or less, more preferably 10,000 ppm or less, based on the weight of the aliphatic polyester resin. Preferably there is. If it exceeds 30000 ppm, the tendency of deterioration of the appearance due to oligomer ejection becomes prominent, the air scatters into the atmosphere at the time of molding, and the respiratory system is stimulated, or the moldability tends to deteriorate due to ejection of the oligomer on the material surface. There is. On the other hand, the lower limit is usually 100 ppm or more, preferably 500 ppm or more, more preferably 1000 ppm or more. In order to make it less than 100 ppm, it is necessary to remove low molecular weight oligomers using various means. For example, with solvent washing, there are problems such as mixing of solvent into the resin, increased cost for washing, and deterioration of the resin. become.

Aliphatic polyester resins can also be obtained as commercial products, for example, GSPla (registered trademark) manufactured by Mitsubishi Chemical Corporation, Bionore (registered trademark) manufactured by Showa Polymer Co., Ltd., and Lacia (registered trademark) manufactured by Mitsui Chemicals, Inc. Daicel Chemical Industries, Ltd., Cell Green (registered trademark), and the like.
The content of the biodegradable resin (A) in the starch-containing resin composition (Y) of the present invention is usually 30% or more by weight, based on the whole starch-containing resin composition (Y) as a standard (100%). The upper limit of the content is 90% or less, preferably 80% or less, more preferably 70% or less. If the content of the biodegradable resin (A) is too large, the physical properties such as the tearing strength are lowered and the cost is not preferred. On the other hand, when there is too little content of biodegradable resin (A), physical properties, such as a tensile elasticity modulus, will fall, or film moldability will deteriorate, and it is unpreferable.

<Thermoplastic resin (B)>
The thermoplastic resin (B) is not limited as long as it has a different thermoplasticity from the resin used as the resin (A), and a known thermoplastic resin may be used as long as the effects of the present invention are not significantly impaired. it can. The thermoplastic resin (B) is a resin specifically exemplified as a resin that can be used as the resin (A) without inhibiting the use of a biodegradable resin, as long as the resin is different from the resin (A). It does not matter. More specifically, polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6 and nylon 66; polystyrene; methacrylic resin; polycarbonate; polyvinyl chloride; Vinyl copolymers; various thermoplastic elastomers such as olefins and styrenes. Of these, aromatic-aliphatic polyesters are preferably used. These thermoplastic resins may be used alone or in combination of two or more.

Hereinafter, an aromatic-aliphatic polyester resin preferable as the thermoplastic resin (B) will be described. In the aliphatic aromatic polyester-based resin, a structural unit in which at least a part of the structural units of the above-described aliphatic polyester-based resin includes an aromatic (hereinafter sometimes referred to as “aromatic unit” as appropriate). A polyester resin.
Examples of the aromatic unit include an aromatic diol unit having an aromatic hydrocarbon group which may have a substituent, and an aromatic dicarboxylic acid unit having an aromatic hydrocarbon group which may have a substituent. And an aromatic oxycarboxylic acid unit having an aromatic hydrocarbon group which may have a substituent. The aromatic hydrocarbon group may be a single ring, or may be one in which a plurality of rings are bonded to each other or condensed. Specific examples of the aromatic hydrocarbon group include 1,2-phenyl group, 1,3-phenyl group, 1,4-phenyl group, dinaphthyl group, diphenyl group and the like.

Specific examples of the aromatic dicarboxylic acid component that provides the aromatic dicarboxylic acid unit include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and the like. Of these, terephthalic acid is preferred.
The aromatic dicarboxylic acid component may be a derivative of an aromatic dicarboxylic acid compound. For example, the derivatives of the aromatic dicarboxylic acid components exemplified above are preferable, and among them, lower alkyl esters having 1 to 4 carbon atoms, acid anhydrides, and the like can be given. Specific examples of the derivatives of the aromatic dicarboxylic acid compound include the above exemplified aromatic dicarboxylic acid components such as methyl ester, ethyl ester, propyl ester and butyl ester, lower alkyl esters; succinic anhydride and the like. Cyclic acid anhydrides of a group dicarboxylic acid component; and the like. Of these, dimethyl terephthalate is preferable.

  Specific examples of the aromatic diol component that gives an aromatic diol unit include, for example, xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4′-hydroxyphenyl) propane, 2,2-bis ( 4'-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid and the like. The aromatic diol component may be a derivative of an aromatic diol compound. Further, it may be a compound having a structure in which a plurality of aliphatic diol compounds and / or aromatic diol compounds are dehydrated and condensed with each other.

  Specific examples of the aromatic oxycarboxylic acid component that gives an aromatic oxycarboxylic acid unit include p-hydroxybenzoic acid and p-β-hydroxyethoxybenzoic acid. The aromatic oxycarboxylic acid component may be a derivative of an aromatic oxycarboxylic acid compound. Further, it may be a compound (oligomer) having a structure in which a plurality of aliphatic oxycarboxylic acid compounds and / or aromatic oxycarboxylic acid compounds are dehydrated and condensed with each other. That is, an oligomer may be used as a raw material.

  When an optical isomer exists in the aromatic component that gives these aromatic units, any of D-form, L-form, and racemate may be used. Moreover, as an aromatic component, if an aromatic unit can be given to (A) aliphatic polyester-type resin, it will not be limited to said example. Furthermore, an aromatic component may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  As the aromatic-aliphatic polyester-based resin used in the starch-containing resin composition of the present invention, it is preferable to use an aromatic dicarboxylic acid component as a component that gives an aromatic unit. The content is preferably 10 mol% or more and 80 mol% or less based on the total amount of aliphatic dicarboxylic acid units and aromatic dicarboxylic acid units (100 mol%). Further, terephthalic acid is preferably used as the aromatic dicarboxylic acid component, and the (C) aliphatic aromatic polyester resin is preferably a polybutylene terephthalate adipate and / or a polybutylene terephthalate succinate resin.

  The method for producing the aromatic-aliphatic polyester resin is not limited as long as the effects of the present invention are not significantly impaired, and can be produced by any known method. For example, a melt polymerization method in which an esterification reaction and / or a transesterification reaction between a dicarboxylic acid component and a diol component is performed, and then a polycondensation reaction is performed under reduced pressure, a solution heating dehydration condensation method using an organic solvent, etc. Can be manufactured by. Among these, from the viewpoint of economy and simplicity of the production process, a melt polymerization method carried out in the absence of a solvent is preferable.

In addition, the aromatic-aliphatic polyester-based resin may be derived from biomass resources as in the above-described biodegradable resin (A). The kind of biomass resource and its manufacturing method can also illustrate the same thing as biodegradable resin (A).
The preferred melt flow index (MFI) of the aromatic-aliphatic polyester-based resin is usually 0.1 g / 10 min or more, usually 100 g / 10 min or less, preferably 50 g when measured at 190 ° C. and 2.16 kg. / 10 minutes or less, more preferably 30 g / 10 minutes or less. Here, MFI is a value at 190 ° C. and a load of 2.16 kg, measured according to the thermoplastic flow test method defined in JIS K7210.

The preferred weight average molecular weight of the aromatic-aliphatic polyester resin is usually 10,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and usually 1,000,000 or less, preferably 800,000 or less, more preferably 600,000 or less. If it is out of this range, it tends to be difficult to perform various molding processes.
The preferable melting point of the aromatic-aliphatic polyester resin is usually 60 ° C. or higher, preferably 70 ° C. or higher, more preferably 80 ° C. or higher, and usually 150 ° C. or lower, preferably 140 ° C. or lower, more preferably 120 ° C. It is below ℃. The melting point can be measured, for example, by differential scanning calorimetry (DSC). Specifically, using a DSC7 differential scanning calorimeter manufactured by Perkin Elmer, Inc., the sample was heated from room temperature to 230 ° C. under the condition of 80 ° C./min, held at the same temperature for 10 minutes, and then −10 The temperature is lowered to 40 ° C. at a temperature of 40 ° C./minute, held at the same temperature for 3 minutes, and then the melting point can be the peak temperature when melted under a temperature rising condition of 10 ° C./minute.

Aromatic-aliphatic polyester-based resins can also be obtained as commercial products, such as Apexa (registered trademark) (formerly Biomax (registered trademark)), BASF, EI DuPont de Nemours & Co. The company Ecoflex (registered trademark) and the like.
The content of the thermoplastic resin (B) different from the resin (A) in the starch-containing resin composition (Y) of the present invention is a weight ratio based on the whole starch-containing resin composition (100%), and is usually 2 % Or more, preferably 5% or more, usually less than 30%, preferably 25% or less. If the content of the thermoplastic resin (B) different from the resin (A) is too large, the stiffness of the film obtained from the biodegradable resin composition is insufficient, and the biodegradation rate is lowered, which is not preferable. On the other hand, when the content of the thermoplastic resin (B) different from the resin (A) is too small, the dispersibility of starch is deteriorated, and the tensile modulus and tear strength are insufficient, which is not preferable.

<Starch (C)>
Starch used in the starch-containing resin composition according to the present invention (C) is a molecular formula _{(C 6 H 10 O 5)} n of carbohydrates (polysaccharides), a number of α- glucose molecules are polymerized by glycosidic bonds It refers to natural polymers and their modified products. “Modification” includes all modification methods such as chemical, physical and biological. As chemical modification, some or all of the structural units of carbohydrates (polysaccharides) are modified by chemical reactions such as esterification, etherification, oxidation, reduction, coupling, dehydration, hydrolysis, dehydrogenation, and halogenation. In particular, it indicates that the hydroxyl group is etherified or esterified. Physical modification means changing physical properties such as changing the crystallinity. Biological degeneration refers to changing a chemical structure or the like using a living organism.

Specific examples of the starch (C) used in the starch-containing resin composition according to the present invention include corn starch, waxy corn starch, high amylose corn starch, wheat starch, rice starch, potato starch, sweet potato starch, tapioca starch, A pea starch etc. are mentioned, A corn starch, a potato starch, etc. are preferable and a corn starch is the most preferable.
The starch used in the present invention is added with a plasticizer such as an organic compound having a hydroxyl group, which will be described later, and heated while applying external force as necessary, whereby the starch particles are destroyed and the fluidity at high temperature is increased. To have.
In the starch-containing resin compositions (X) and (Y) of the present invention, the starch (C) has an average dispersion diameter of 1 μm or less in the resin composition from the viewpoint of improving physical properties such as tear strength and tensile elastic modulus. It is preferable that it exists at 0.7 micrometer or less, More preferably, it exists at 0.5 micrometer or less. In addition, the average dispersion diameter of a starch here is an average value of a circle | round | yen equivalent diameter (the diameter when the area of a starch phase is measured and a perfect circle with the area is drawn).

  In the starch-containing resin composition (X) of the present invention, the content of starch (C) is usually 30% or more, preferably a weight ratio based on the whole starch-containing resin composition (X) (100%). The upper limit is 35% or more, and the upper limit is 60% or less, preferably 50% or less. (B) When there is too much content of starch, since the dispersion diameter of the starch in a composition may become large, it is unpreferable. On the other hand, if the content of the starch (B) is too small, the thermoplasticity of the starch becomes insufficient, the physical properties such as tear strength and tensile elastic modulus are reduced, and the production cost of the biodegradable resin composition is low. It is not preferable because it rises.

  In the starch-containing resin composition (Y) of the present invention, the content of starch (C) is a weight ratio based on the whole starch-containing resin composition (Y) (100%), and usually 5% or more, preferably It is 10% or more, and the upper limit is 30% or less, preferably 20% or less. When there is too little content of starch (C), mechanical properties, such as tear strength, will fall. On the other hand, if the content of starch (C) is too large, the biodegradation rate becomes too fast and the biodegradability of the molded product may be inferior.

<Organic compound having hydroxyl group (D)>
The organic compound (D) containing a hydroxyl group used in the starch-containing resin composition according to the present invention is not particularly limited as long as it has a hydroxyl group. Examples thereof include alcohols, partial esters or partial ethers of polyhydric alcohols. Among these, sorbitol, pentaerythritol, trimethylolpropane, trimethylolethane, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-heptanediol, 1, 6-hexanediol, 1,8-octanediol, 1,9-nanonediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol , Polypropylene glycol, glycerol, glycerol monoalkyl ester, glycerol dialkyl ester, glycerol monoalkyl ether, glycerol dialkyl ether, diglycerol, diglycerol alkyl Ester etc., more preferably ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, glycerin monoester, sorbitol or pentaerythritol, particularly preferably glycerin, sorbitol, pentaerythritol, propylene glycol or ethylene glycol . One or more organic compounds containing a hydroxyl group are used.

The molecular weight of the organic compound (D) containing a hydroxyl group is preferably 3000 or less, more preferably 2500 or less, and particularly preferably 2000 or less.
The content of the organic compound (D) containing a hydroxyl group in the starch-containing resin composition (X) is usually 3% by weight or more and 20% by weight or less based on the whole starch-containing resin composition (X) (100% by weight). It is. The content of the organic compound (D) containing a hydroxyl group is preferably 15% by weight or less, particularly preferably 10% by weight or less. On the other hand, it is preferably 5% by weight or more, more preferably 7% by weight or more, and particularly preferably 10% by weight or more. If the content of the organic compound (D) containing a hydroxyl group is too small, plasticization of the added starch does not proceed sufficiently, and the thermoplasticity different from the resin (A) and resin (A) having starch biodegradability Since the dispersion into the resin (B) is not good, the mechanical properties may decrease. On the other hand, when the content of the organic compound containing a hydroxyl group is too large, the melt viscosity of the starch-containing resin composition (X) becomes too low, so that the resin (A) having biodegradability in the step (ii) described later And the mixed state of the thermoplastic resin (B) different from the resin (A) may be deteriorated.
The content of the organic compound containing a hydroxyl group in the starch-containing resin composition (Y) is usually 1% by weight or more and 10% by weight or less based on the whole starch-containing resin composition (Y) (100% by weight). The content of the organic compound (D) containing a hydroxyl group is preferably 9% by weight, particularly preferably 8% by weight. On the other hand, it is preferably 2% by weight or more, particularly preferably 3% by weight or more. If the content of the organic compound (D) containing a hydroxyl group is too small, a resin having biodegradability (A), particularly an oligomer derived from an aliphatic polyester resin, is deposited on the surface, or the mechanical properties of the molded product are lowered. Sometimes. On the other hand, when the content of the organic compound containing a hydroxyl group is too large, the organic compound containing a hydroxyl group is segregated on the surface of the molded article, and the properties such as the surface appearance may be impaired, and the elastic modulus of the molded product may be too low. is there.

<Other additives>
The biodegradable resin composition of the present invention can further contain various conventionally known additives. Examples of such additives include inorganic fillers, heat stabilizers, light stabilizers, ultraviolet absorbers, compatibilizers, and antistatic agents. These may be used alone or in combination of two or more. In addition, these substances are previously added to at least one selected from the group consisting of a biodegradable resin (A), a thermoplastic resin (B), starch (C), and an organic compound (D) containing a hydroxyl group. It may be added, may be added during the step of obtaining the starch-containing resin composition (X) by melt-kneading, or from the thermoplastic resin (B) different from the resin (A) and the resin (A). It may be added during the process of diluting with at least one selected resin. Furthermore, other additives can be mixed in any form. For example, it may be mixed as a solid when the resin is melted, mixed as a solution dissolved in a solvent, or as a slurry dispersed in a solvent.

  Examples of the inorganic filler include natural minerals, potassium titanate, calcium carbonate, basic magnesium sulfate, sepiolite, zonotlite, aluminum borate, acicular magnesium hydroxide, and other acicular fillers such as whiskers; glass fiber, carbon Fibrous inorganic fillers such as fiber, silica fiber, silica / alumina fiber, zirconia, rock wool; talc, mica, graphite, BN (hexagonal crystal), MIO (plate iron oxide), plate calcium carbonate, plate water Examples thereof include plate-like particles such as aluminum oxide, glass flakes and various metal foils; spherical calcium carbonate, silica, clay and various beads. Of these, fillers such as talc and mica are preferable.

  Examples of the heat stabilizer include dibutylhydroxytoluene (BHT; 2,6-di-t-butyl-4-methylphenol), 2,2′-methylenebis (4-methyl-6-t-butylphenol), pentaerythritol tetrakis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′, a ″ -(Mesitylene-2,4,6-triyl) tri-p-cresol, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-tris [(4 -Tert-butyl-3-hydroxy-2,6-xylyl) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3,5-to (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 and other hindered phenol thermal stabilizers; tridecyl phosphite, diphenyl decyl phosphite , Tetrakis (2,4-di-tert-butylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphonite, bis [2,4- (1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphorous acid stabilizers such as phosphorous acid, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite; 3-hydroxy Lactone-based thermal stabilizers such as -5,7-di-tert-butyl-furan-2-one and xylene reactive organisms; sulfur-based antioxidants such as dilauryl thiodipropionate and distearyl thiodipropionate And so on.

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

  Examples of the light stabilizer include bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester decaneate, a reaction product of 1,1-dimethylethyl hydroperoxide and octane, bis ( 1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate, 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-1,3,5-triazine -2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] And hindered amine stabilizers. The light stabilizer is preferably used in combination with an ultraviolet absorber, and a combination of a hindered amine stabilizer and an ultraviolet absorber is effective.

  The amount of the light-resistant agent to be mixed is usually 100 ppm or more, preferably 200 ppm or more, and usually 5 parts by weight or less, preferably 1 part by weight or less, more preferably, on a weight basis with respect to the biodegradable resin composition. 0.5 parts by weight or less. Below this range, the effect of the light resisting agent tends to be small. Moreover, when it exceeds this range, the manufacturing cost tends to be high, the heat resistance of the biodegradable resin composition tends to be inferior, and the light-proofing agent tends to bleed out.

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

  The amount of the ultraviolet absorber to be mixed is arbitrary as long as the effects of the present invention are not significantly impaired. However, the biodegradable resin composition is usually 100 ppm or more, preferably 200 ppm or more, and usually 5 wt. % Or less, preferably 2% by weight or less, more preferably 0.5% by weight or less. Below this range, the effect of the ultraviolet absorber tends to decrease. Moreover, when it exceeds this range, the manufacturing cost tends to be too high, the heat resistance of the biodegradable resin composition is inferior, or the ultraviolet absorber bleeds out.

As a compatibilizer, an ester group, a carboxylic acid anhydride, an amide group, an ether group, a cyano group, an unsaturated hydrocarbon group, an epoxy group, an acrylic group, a methacrylic group, an aromatic group are added to the terminal or main chain of the aliphatic polyester. Examples thereof include compounds obtained by reacting hydrocarbon groups and the like.
Examples of the compatibilizer include aliphatic polyester and aromatic polyester resin such as polyolefin resin, polyurethane resin, polycarbonate resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyarylate, and liquid crystal polymer; Vinyl resin; SEBS (polystyrene-block-poly (ethylene-co-butylene) -block-polystyrene), SEPS (polystyrene-block-poly (ethylene-co-propylene) -block-polystyrene), styrene resins such as polystyrene; Nylon 6, nylon 6-6, nylon 6-10, nylon 9, nylon 11, nylon 13 nylon 4, nylon 4-6, nylon 5-6, nylon 12, nylon 10-12, Polyamide resins such as ramids; Riacetal resins; Acrylic resins such as polymethyl methacrylate, polymethacrylic acid ester, polyacrylic acid ester; Polyethylene glycol, polypropylene glycol, poly 1,3-propanediol, polytetramethylene glycol, modified polyphenylene Polyether resins such as ether; polyphenylene sulfide resin; polyether ketone resin; polyether ether ketone resin; Moreover, the graft copolymer with the above-mentioned resin, a block copolymer, a multiblock copolymer, a random copolymer etc. are mention | raise | lifted.

  Further, in addition to the above-mentioned copolymer, examples of the compatibilizing agent include compounds containing both different resin structures to be blended in the same molecule. Also, polyurethane resin, polycarbonate resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, SEBS, SEPS, polystyrene, nylon 6, nylon 6-6, nylon 12, polyacetal resin, polymethyl methacrylate, polymethacrylate, polyacryl Reacts with hydroxyl group, carboxyl group, ester group, alkyl group, alkylene group at the end or side chain of polymer molecule of acrylic resin such as acid ester, polyethylene glycol, polypropylene glycol, poly 1,3-propanediol, polytetramethylene glycol Examples include polymers having possible functional groups.

  The amount of the compatibilizer to be mixed is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01 parts by weight or more, preferably 0.1 parts by weight or more, relative to the biodegradable resin composition More preferably 1 part by weight or more, and usually 50 parts by weight or less, preferably 30 parts by weight or less, more preferably 10 parts by weight or less. Above this range, manufacturing costs tend to be high. Moreover, when it is less than this range, the effect of the compatibilizer tends to be small.

Any antistatic agent can be used as long as the effects of the present invention are not significantly impaired. As a specific example, a surfactant type nonionic, cationic or anionic type is preferable.
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 and the like are listed. 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. Of these, alkylbenzene sulfonate is preferable. This is because the kneadability with the resin is good and the antistatic effect is high.

  The amount of the antistatic agent used is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.5% by weight or more, preferably 1% by weight or more, and usually 5% by weight with respect to the biodegradable resin composition. % By weight or less, preferably 3% by weight or less. If it exceeds the above range, the biodegradable resin composition will have surface stickiness and the product value tends to be reduced. On the other hand, if it is below the above range, the effect of improving the antistatic property tends to be reduced.

  Other additives may be added to the resin composition and each resin component of the present invention. Specifically, antioxidants, antiblocking agents, plasticizers, colorants, flame retardants, mold release agents. Antistatic agents, antifogging agents, surface wetting improvers, incineration aids, pigments, lubricants, dispersion aids, various surfactants, slip agents, hydrolysis inhibitors, freshness-preserving agents, antibacterial agents and the like. These may be used alone or in combination of two or more. The amount of these additives is usually 0.01% by weight or more and 10% by weight based on the total amount of the biodegradable resin composition in order not to impair the physical properties of the biodegradable resin composition. It is preferable that it is below wt%.

<Production of starch-containing resin composition (X)>
In the present invention, the resin (A) having biodegradability, the thermoplastic resin (B) different from the resin (A), starch (C), and the organic compound (D) having a hydroxyl group are melt-kneaded. The starch-containing resin composition (X) according to the present invention is produced (hereinafter sometimes abbreviated as step (i)).

When melt-kneading the material used in step (i), any conventionally known mixing / kneading technique can be applied as long as the materials used are sufficiently mixed.
As the mixer, a horizontal cylindrical type, V-shaped, double-cone type mixer, a blender such as a ribbon blender or a super mixer, various continuous mixers, or the like can be used. As the kneader, a batch kneader such as a roll or an internal mixer, a single-stage or two-stage continuous kneader, a twin screw extruder, a single screw extruder, or the like can be used. In this invention, it is preferable to use a twin screw extruder from the point of kneading | mixing efficiency, and also the thing whose rotation direction of a screw is the same direction is preferable.

Hereinafter, although an example of the melt kneading method in the step (i) according to the present invention will be shown, the present invention is not limited to the following kneading method, and is a conventionally known method as long as the effect of the present invention is not hindered. The embodiment may be modified by a kneading technique.
A schematic diagram of a twin screw extruder preferably used for the production of the biodegradable resin composition of the present invention is shown in FIG. The twin screw extruder 100 includes two screw shafts 2 that are arranged in parallel in the cylinder 1 and mesh with each other. The cylinder 1 includes a main raw material supply unit 3 located on the upstream side in the feed direction and a secondary raw material supply unit 5 located on the downstream side in the feed direction. Vent portions 4 and 6 are provided, respectively.

  From the main raw material supply unit 3, usually, starch (C), a thermoplastic resin (B) different from the resin (A), and an organic compound (D) having a hydroxyl group are supplied, melted and kneaded into a composition, It is sent in the cylinder downstream direction. The temperature at the time of melt kneading needs to be at least higher than the melting point of the plasticized starch and the resin, and is usually 100 to 180 ° C, preferably 130 to 170 ° C. Gas components such as air, water vapor and raw material-derived volatile components contained in the melted composition are partly from the vent portion 4 which is an open vent and exists between the main raw material supply portion 3 and the auxiliary raw material supply portion 5. It is discharged and separated and devolatilized.

The devolatilized composition is further melt-kneaded with the biodegradable resin (A) side-feeded from the auxiliary raw material supply unit 5 to obtain a starch-containing resin composition (X). Part of gas components such as air, water vapor, and volatile components derived from the raw material contained in the biodegradable resin composition (X) is sucked in vacuum from the vent portion 6 that is a suction vent and exhausted to the outside.
The molten starch-containing resin composition (X) that has passed through the vent portion 6 is extruded into water in the form of a melted strand from the die head 7 and cooled and solidified, and after being cut with a pelletizer (not shown), It is set as a biodegradable resin composition pellet by drying. In the illustrated form, the starch-containing resin composition devolatilized by the twin-screw extruder 100 is once pelletized through the die head 7 and the pelletizer, but is continuously supplied to the molding machine in a molten state to form a film or the like. It may be molded.

  In the step (i), the ratio of the thermoplastic resin (B) different from the resin (A) and the starch (C) ([weight of the thermoplastic resin (B)] × 100 / [weight of starch (C)] ) Is preferably 20% or more, more preferably 25% or more, and particularly preferably 30% or more. Further, it is preferably 70% or less, more preferably 60% or less, and particularly preferably 50% or less. When this ratio is too small, the starch dispersion diameter in the starch-containing resin composition increases, and the mechanical properties of the molded product obtained from the starch-containing resin composition (Y) finally obtained may deteriorate. When this ratio is too large, the organic compound (D) having a hydroxyl group cannot sufficiently diffuse into the starch particles, and the plasticization of starch may not sufficiently proceed.

  In the obtained biodegradable resin composition (X), at least one resin selected from a resin (A) having biodegradability and a thermoplastic resin (B) different from the resin (A) usually forms a sea phase. And among starch (C), resin (A), and thermoplastic resin (B), what did not form a sea phase is a starch-containing resin composition having a sea-island structure in which an island phase is formed. . The average dispersion diameter of the starch phase is preferably 1 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.3 μm or less. When the average dispersion diameter of the starch phase is larger than 1 μm, the starch-containing resin composition (X) described later is diluted with at least one resin selected from the resin (A) and the thermoplastic resin (B) different from the resin (A). In some cases, the mechanical properties of the molded product obtained from the starch-containing resin composition (Y) obtained through the step (hereinafter, may be abbreviated as step (ii)) are deteriorated.

  In addition, the average dispersion diameter of the island phase of each component in the starch-containing resin composition is obtained by performing ion etching on the starch-containing resin composition and subsequently performing gold vapor deposition using a transmission electron microscope (TEM). And observed as an average value of the equivalent circle diameter of each island phase of each component existing in the range of 5 μm × 5 μm of the TEM image. The average dispersion diameter may be measured basically for one biodegradable resin composition pellet taken out arbitrarily, but when the value varies greatly from pellet to pellet, the pellet 100 extracted at random is used. The average value of the individual pieces can be used as the average dispersion diameter.

<Production of starch-containing resin composition (Y)>
In the step (ii) of producing the starch-containing resin composition (Y), at least the starch-containing resin composition (X) described above is selected from a resin (A) and a thermoplastic resin (B) different from the resin (A). Dilute with one resin.

In the step (ii), when the starch-containing resin composition (X) is diluted with at least one resin selected from the resin (A) and a thermoplastic resin (B) different from the resin (A), the material used is Any conventionally known mixing / kneading technique can be applied as long as it is sufficiently mixed.
As the mixer, a horizontal cylindrical type, V-shaped, double-cone type mixer, a blender such as a ribbon blender or a super mixer, various continuous mixers, or the like can be used. As the kneader, a batch kneader such as a roll or an internal mixer, a single-stage or two-stage continuous kneader, a twin screw extruder, a single screw extruder, or the like can be used. In this invention, it is preferable to use a twin screw extruder from the point of kneading | mixing efficiency, and also the thing whose rotation direction of a screw is the same direction is preferable.

  The ratio of the thermoplastic resin (B) different from the resin (A) in the starch-containing resin composition (Y) is a weight ratio based on the starch-containing resin composition (Y) (100%), preferably 2 % By weight or more, more preferably 5% by weight or more, particularly preferably 7% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less, and particularly preferably 20% by weight or less. When the thermoplastic resin (B) different from the resin (A) is too small, the average dispersion diameter of the starch (C) in the starch-containing resin composition (Y) becomes large and is obtained from the starch-containing resin composition (Y). The mechanical strength of the molded product may be inferior. If the amount is too large, the mechanical properties of the starch-containing resin composition (Y) may be inferior.

  The starch-containing resin composition of the present invention can be used for molding by various molding methods applied to general-purpose plastics. Examples of the molding method include compression molding (compression molding, laminate molding, stampable molding), injection molding, extrusion molding and coextrusion molding (film molding by inflation method and T-die method, laminate molding, pipe molding, electric wire / cable molding. , Profile molding), hollow molding (various blow molding), calender molding, foam molding (melt foam molding, solid phase foam molding), solid molding, uniaxial stretching molding, biaxial stretching molding, roll rolling molding, stretch oriented nonwoven fabric Examples thereof include molding, thermoforming (vacuum forming, pressure forming), plastic working, powder forming (rotary forming), various non-woven fabric forming (dry method, adhesion method, entanglement method, spunbond method, etc.). Of these, extrusion molding is preferable, and inflation molding is particularly preferably applied. The specific shape of the biodegradable resin composition molded body is preferably applied to a film.

<Physical Properties of Film Obtained from Starch-Containing Resin Composition of the Present Invention>
In the film obtained from the starch-containing resin composition of the present invention, the Elmendorf tear strength in the MD direction of the film in accordance with JIS K7128 is 10 N / mm or more, preferably 20 N / mm, although not particularly limited thereto. More preferably, it is 30 N / mm. Further, the Elmendorf tear strength in the TD direction of the film according to JIS K7128 is 10 N / mm or more, preferably 20 N / mm, more preferably 30 N / mm. If the tear strength is too low, tearing may occur during actual use, and trouble may occur during film formation.

  Further, the tensile modulus of elasticity in the MD direction of the film conforming to JIS K7127 is not particularly limited thereto, but is preferably 100 MPa to 800 MPa, more preferably 200 MPa to 750 MPa, and particularly preferably 250 MPa to 700 MPa. The tensile modulus of elasticity in the TD direction of the film according to JIS K7127 is not particularly limited to this, but is preferably 100 MPa to 800 MPa, more preferably 200 MPa to 750 MPa, and particularly preferably 250 MPa to 700 MPa. If the tensile modulus is too low, it may not be able to withstand the weight of the contents depending on the thickness of the film when used as a packaging material for garbage bags, shopping bags, shopping bags, compost bags and the like. Moreover, when too large, the flexibility of a film may be impaired and usability may worsen.

  The film made of the starch-containing composition produced by the production method of the present invention preferably has a weight loss in soil of less than 10% in a soil under an environment of 40 ° C. A more preferred weight loss rate is less than 8%. If the weight reduction rate is too high, the deterioration may progress before the period required in applications where biodegradability is required, and the physical properties may deteriorate.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist.
1. Evaluation of physical properties [1-1. Evaluation of film formability]
The ease of molding when performing inflation molding was evaluated according to the following criteria.

Good (◯): It is possible to mold to a predetermined thickness (20 μm) at a predetermined temperature (150 ° C.).
Defect (x): It is impossible to mold to a predetermined thickness (20 μm) at a predetermined temperature (150 ° C.).

[1-2. Observation of the internal form of the film]
The dispersion form of starch in the film was observed using a transmission electron microscope (TEM).
[1-3. Mechanical strength of film]
<Measurement method of tear strength>
Elmendorf tear strength was measured in accordance with JIS K7128.

<Tensile test>
In accordance with JIS Z1702, a tensile test of the film was carried out with a precision universal testing machine Autograph AG-2000 manufactured by Shimadzu Corporation.
[1-4. Biodegradability of film]
The soil in the Yokkaichi Office of Mitsubishi Chemical Corporation was collected and adjusted so that the moisture content of the soil was 20% by weight. The soil was placed in a constant temperature bath at 40 ° C., and the obtained film (thickness 20 μm) was embedded. The water lost from the soil during the test was measured from the weight loss of the entire soil and film and added as appropriate to maintain a constant water content. One week after embedment, the film was taken out and conditioned at 23 ° C. and 50% RH, then the weight of the film was measured, and the weight loss was evaluated as follows.

○: Weight reduction amount less than 10% Δ: Weight reduction amount from 10% to less than 20% ×: Weight reduction amount of 20% or more

2. Production of resin composition [2-1. Aliphatic polyester resin (A)]
GS Pla (AD92WN; polybutylene succinate adipate) was used as the aliphatic polyester resin.
[2-2. Aromatic aliphatic polyester (B)]
As the aromatic aliphatic polyester resin, Ecoflex (polybutylene adipate terephthalate) manufactured by BASF was used.
[2-3. Starch (C)]
As starch, corn starch (Y-3P, manufactured by Nippon Corn Starch Co., Ltd .; water content: 12%) not subjected to any chemical modification was used.
[2-4. Organic compound containing hydroxyl group (D)]
As an organic compound containing a hydroxyl group, glycerin (concentrated glycerin S manufactured by Shin Nippon Rika Co., Ltd.) was used.

・ Production Example 1
Starch (C) 35.5 parts by weight, aromatic aliphatic polyester resin (B) 17.7 parts by weight, glycerin (D) 7.4 parts by weight, screw-type twin-screw extruder (Nippon Steel Works TEX30; 22 cylinders, L / D = 77) After supplying the main raw material supply part and mixing so that the maximum temperature is 170 ° C. or less, water vapor is removed at the vent part, and then the auxiliary raw material supply 42.4 parts by weight of aliphatic polyester resin (A-1) is supplied from the parts, and corn starch, glycerin, aromatic aliphatic polyester resin, and aliphatic polyester resin are mixed so that the maximum temperature is 170 ° C. or less. The process is performed sequentially in the same extruder, sucked by a vacuum vent, the resin composition is extruded from a die into a strand shape, cooled in a water bath, cut and then white starch It was obtained organic resin composition (X-1). The set temperature at the time of kneading was 80 to 150 ° C., and the screw rotation speed was 150 to 300 rpm. Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.

・ Production example 2
41.7 parts by weight of starch (C), 20.8 parts by weight of aromatic aliphatic polyester resin (B) and 7.9 parts by weight of glycerin (D) were mixed with a screw-type twin screw extruder (TEX30 manufactured by Nippon Steel Works; 22 cylinders, L / D = 77) After supplying the main raw material supply part and mixing so that the maximum temperature is 170 ° C. or less, water vapor is removed at the vent part, and then the auxiliary raw material supply 29.6 parts by weight of the aliphatic polyester resin (A) from a part, and mixing the corn starch, glycerin, the aromatic aliphatic polyester resin, and the aliphatic polyester resin so that the maximum temperature is 170 ° C. or less. Sequentially performed in the same extruder, suctioned by a vacuum vent, the resin composition is extruded in a strand form from a die, cooled in a water tank and cut, containing white starch It was obtained fat composition (X-2). The set temperature at the time of kneading was 80 to 150 ° C., and the screw rotation speed was 150 to 300 rpm. Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.
Table 1 below summarizes the composition ratios of the starch-containing resin compositions produced in Production Example 1 and Production Example 2.

Example 1
70 parts by weight of the starch-containing resin composition (X-1) obtained in Production Example 1 and 30 parts by weight of the aliphatic polyester (A) were blended, and a screw type twin screw extruder (Technobel twin screw extruder (KZW15) )) From the main raw material supply unit, and kneading was performed so that the maximum temperature was 170 ° C. or less to obtain a resin composition (Y-1). The pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.
Using the obtained resin composition (Y-1), inflation molding was carried out with an inflation molding machine (Empura Sangyo Co., Ltd .; E30SP) to obtain a film having a thickness of 20 μm. The molding conditions are a blow ratio of 2.5 and a molding temperature of 150 ° C.
Table 3 below shows the physical property measurement results and evaluation results, such as biodegradability of the obtained film, tear strength, and tensile strength of the film.

Examples 2-7
The blend composition of the starch-containing resin composition (X-1), (X-2), the aliphatic polyester resin (A), and the aromatic aliphatic polyester resin (B) was as described in Table 2, Resin compositions (Y-2) to (Y-7) are produced in the same manner as in Example 1, and a film having a thickness of 20 μm is obtained by the same molding method as in Example 1 using the obtained resin composition. It was. Table 3 below shows the physical property measurement results and evaluation results, such as biodegradability of the obtained film, tear strength, and tensile strength of the film.

Comparative Example 1
Aliphatic polyester resin (A) 57.6 parts by weight, starch (C) 24.9 parts by weight, aromatic aliphatic polyester resin (B) 12.4 parts by weight, glycerin (D) 5.2 parts by weight, screw Supply to the main raw material supply section of a twin screw extruder (TEX30 manufactured by Nippon Steel Works; 22 cylinders, L / D = 77) and mix so that the maximum temperature is 170 ° C or less, and suction is performed by a vacuum vent. The resin composition was extruded from a die in a strand shape, cooled in a water tank and then cut to obtain a white starch-containing resin composition (Z-1). The set temperature at the time of kneading was 80 to 150 ° C., and the screw rotation speed was 150 to 300 rpm. Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.
Using the obtained starch-containing resin composition (Z-1), a film having a thickness of 20 μm was obtained by the same molding method as in Example 1. Table 3 below shows the physical property measurement results and evaluation results, such as biodegradability of the obtained film, tear strength, and tensile strength of the film.

Comparative Example 2
Aliphatic polyester resin (A) 78.9 parts by weight, starch (C) 12.5 parts by weight, aromatic aliphatic polyester resin (B) 6.2 parts by weight, glycerin (D) 2.4 parts by weight, screw Supply to the main raw material supply section of a twin screw extruder (TEX30 manufactured by Nippon Steel Works; 22 cylinders, L / D = 77) and mix so that the maximum temperature is 170 ° C or less, and suction is performed by a vacuum vent. The resin composition was extruded from a die in a strand shape, cooled in a water tank and cut to obtain a white starch-containing resin composition (Z-2). The set temperature at the time of kneading was 80 to 150 ° C., and the screw rotation speed was 150 to 300 rpm. Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.
Using the obtained starch-containing resin composition (Z-2), a film having a thickness of 20 μm was obtained by the same molding method as in Example 1. Table 3 below shows the physical property measurement results and evaluation results, such as biodegradability of the obtained film, tear strength, and tensile strength of the film.

Comparative Example 3
In the same manner as in Example 1, the aliphatic polyester resin (A) was subjected to inflation molding, and mechanical properties such as evaluation of film biodegradability, film tear strength, and tensile strength were evaluated.
The films produced in Examples 1 to 7 had good mechanical properties and good biodegradability. In Comparative Examples 1 and 2, since starch is poorly dispersed, and Comparative Example 3 does not contain starch, the mechanical properties of the film, particularly the tear strength, are poor.

1: Cylinder 2: Screw shaft 3: Main raw material supply unit 4: Vent unit 5: Sub raw material supply unit 6: Vent unit 7: Die head 100: Twin screw extruder

Claims (4)

30% by weight or more and 90% by weight or less of aliphatic polyester resin (A) , 2% by weight or more and less than 30% by weight of resin (A) different from aromatic-aliphatic polyester resin (B), 5% by weight or more and 30% by weight A method for producing a starch-containing resin composition (Y) comprising the following starch (C) and an organic compound (D) containing 1 to 10% by weight of a hydroxyl group,
(I) Aliphatic polyester resin (A), aromatic-aliphatic polyester resin (B) different from resin (A), starch (C) of 30 wt% to 60 wt%, and 3 wt% to 20 wt% A step of obtaining a starch-containing resin composition (X) by melt-kneading the following organic compound (D) containing a hydroxyl group;
And (ii) the starch-containing resin composition (X), and different aromatic aliphatic polyester resin (A) and the resin (A) - a step of dilution with at least one resin selected from the aliphatic polyester resin (B) ,
The manufacturing method of the starch-containing resin composition (Y) which has. It is a manufacturing method of the starch containing resin composition (Y) of Claim 1, Comprising: (i) Using the twin screw type extruder which has a main raw material supply part and an auxiliary raw material supply part, from this main raw material supply part An aromatic-aliphatic polyester resin (B) different from the resin (A), starch (C), and an organic compound (D) containing a hydroxyl group are supplied, and the aliphatic polyester resin (A) is added to the secondary polyester resin (A). A step of obtaining a starch-containing resin composition (X) in which the content of starch (C) is 30 wt% or more and 60 wt% or less by supplying from the raw material supply section and kneading,
And (ii) mixing the resin composition (X) with the aliphatic polyester resin (A) and an aromatic-aliphatic polyester resin (B) different from the resin (A). Manufacturing method of thing (Y). The ratio of the aromatic-aliphatic polyester resin (B) different from the resin (A) in the step (i) to the starch (C) is 20% by weight or more and 70% by weight or less. The manufacturing method of the starch-containing resin composition (Y) of description. The starch-containing resin composition according to any one of claims 1 to 3 , wherein the aliphatic polyester resin (A) is at least one selected from polybutylene succinate and polybutylene succinate adipate. The manufacturing method of (Y).

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