JP2013049760A - Method of producing resin composition, and methods of producing molded product, film, and bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a resin composition excellent in moldability.SOLUTION: The resin composition comprises a thermoplastic resin (A), a starch (B), a plasticizer (C), and a lubricant (D). The method of producing the resin composition includes: a plasticizing step of mixing the starch (B) with the plasticizer (C) to thereby plasticize the starch; and a lubricant-mixing step of mixing the resultant mixture obtained after the plasticizing step with the lubricant (D).

Description

  The present invention relates to a method for producing a resin composition comprising a thermoplastic resin, starch, a plasticizer, and a lubricant.

  Conventionally, paper, plastic, metal foil, and the like have been used in a wide range of applications such as various foods, medicines, miscellaneous liquids and granules, solid packaging materials, agricultural materials, and building materials. In particular, plastics are excellent in strength, water resistance, moldability, transparency, cost, etc., and are used in many applications such as films, bags, and containers. Typical plastics include, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride 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.

  Various resins have been studied to solve the above problems. For example, a polyester resin that is easily decomposed in a natural environment has attracted attention. A film formed by molding the polyester-based resin is decomposed by, for example, embedding in the soil after use, so that it is possible to prevent global warming and soil and air pollution. However, many films formed by molding a polyester-based resin generally have poor mechanical properties. Therefore, many studies have been made to improve mechanical properties of films formed by molding polyester resins.

  For example, Patent Document 1 discloses a resin composition in which starch, aliphatic polyester, and aliphatic aromatic polyester are mixed at a specific ratio. Patent Document 2 discloses a resin composition having a dispersed phase containing starch and a continuous layer composed of a thermoplastic polymer. Furthermore, Patent Document 3 discloses a resin composition in which starch, aliphatic polyester, and polyhydric alcohol are mixed at a specific ratio.

  Like the resin compositions disclosed in Patent Documents 1 to 3, it is considered that the mechanical properties of a film can be improved by including starch together with a polyester resin. In particular, by plasticizing and dispersing starch in the resin composition, the starch can be uniformly dispersed, and the mechanical properties of the film are further improved. That is, in the resin composition, it is preferable to include a plasticizer together with the polyester resin and starch.

  On the other hand, for example, as described in Patent Document 3, a lubricant such as fatty acid amide may be included in the resin composition. By including the lubricant, it is possible to improve the releasability when the resin composition is molded, and after molding the resin composition, it is possible to prevent the molded bodies from sticking to each other.

JP 2008-13602 A JP 2000-509427 A JP 2003-55470 A

  However, when a lubricant is included in the resin composition, the lubricant has an adverse effect on the molding processability of the resin composition or the plasticization of starch is inhibited, so that the molding processability of the resin composition is obtained. In some cases, the mechanical properties of the molded product may be impaired. More specifically, the melt flow rate (MFR) of the resin composition at the time of melting is remarkably increased, and it becomes difficult to perform extrusion molding or blow molding, or the mechanical strength of the obtained molded product is decreased. In some cases, the appearance of the molded article deteriorated. In view of this, the present invention provides a method for producing a resin composition having excellent molding processability, and a method for producing a molded article, film or bag having excellent mechanical properties and appearance, using the resin composition obtained by the production method. The task is to do.

  As a result of earnest research to solve the above-mentioned problems, the present inventor mixed starch and plasticizer to plasticize starch when producing a resin composition containing a thermoplastic resin, starch, a plasticizer, and a lubricant. It is possible to control the MFR of the resin composition at the time of melting and prevent the plasticization of the starch properly without mixing the lubricant, and to improve the molding processability. And it discovered that the resin composition which has a favorable external appearance and mechanical physical property for a molded article can be manufactured.

The present invention has been made based on the above findings. That is,
1st aspect of this invention is a manufacturing method of the resin composition containing a thermoplastic resin (A), starch (B), a plasticizer (C), and a lubricant (D), Comprising: Starch (B) and It is a manufacturing method of the resin composition which has a plasticizing process which mixes a plasticizer (C) and plasticizes starch, and a lubricant mixing process which mixes a lubricant (D) after the said plasticizing process.

In the present invention, “mixing the lubricant (D) after the plasticizing step” may be in any form as long as the lubricant (D) is mixed in the step after the plasticizing step. Specifically, the following embodiments (I) to (III) can be exemplified.
(I) After the step of mixing starch (B) and plasticizer (C) to plasticize starch (B) to obtain a starch composition, and the starch composition and thermoplastic resin Prior to the step of mixing (A), the starch composition and the lubricant (D) are mixed.
(II) After the step of mixing starch (B) and plasticizer (C) to plasticize starch (B) to obtain a starch composition, the starch composition and thermoplastic containing lubricant (D) Resin (A) is mixed.
(III) Mixing starch (B) and plasticizer (C) to plasticize starch (B) to form a starch composition, and mixing the starch composition and thermoplastic resin (A) Then, the lubricant (D) is mixed.

  1st aspect of this invention WHEREIN: It is preferable that the moisture content contained in starch (B) is 10 wt% or more. When the water content in the starch is 10 wt% or more, the starch is easily plasticized, the starch (B) can be uniformly dispersed in the resin composition, and it has excellent molding processability and mechanical strength. In addition, a more excellent resin composition can be obtained.

  In the first embodiment of the present invention, the starch (B) may be any natural starch that has not been modified or starch that has been modified as appropriate.

  Here, “denaturation” includes all modifications such as chemical, physical and biological. Chemical modification indicates that some or all of the structural units of starch are modified by chemical reactions such as esterification, etherification, oxidation, reduction, coupling, dehydration, hydrolysis, dehydrogenation, halogenation, etc. In particular, it indicates that the hydroxyl group is etherified or esterified. Physical modification refers to changing physical properties such as changing the crystallinity. Biological degeneration refers to changing a chemical structure or the like using a living organism.

  In the first aspect of the present invention, it is preferable to use a fatty acid amide lubricant as the lubricant (D). This is because the adhesion between the molded products can be effectively prevented by using the fatty acid amide lubricant.

  In the first aspect of the present invention, the plasticizer (C) is preferably an organic compound having a hydroxyl group. This is because the starch (B) can be appropriately plasticized.

  In the first aspect of the present invention, the thermoplastic resin (A) is preferably an aliphatic polyester resin. In the present invention, even if an aliphatic polyester-based resin is used as the thermoplastic resin (A), a resin composition having excellent molding processability and excellent mechanical properties can be appropriately produced through the above steps. It is. Since the aliphatic polyester-based resin is decomposed by being embedded in the soil, it is possible to prevent global warming and prevent soil and air pollution.

  A second aspect of the present invention is a method for manufacturing a molded body, which includes a step of molding a resin composition obtained by the manufacturing method according to the first aspect of the present invention.

  A third aspect of the present invention is a film manufacturing method including a step of molding a resin composition obtained by the manufacturing method according to the first aspect of the present invention.

  A 4th aspect of this invention is a manufacturing method of a bag provided with the process of further shape | molding the film obtained by the manufacturing method which concerns on the 3rd aspect of this invention.

When the resin composition according to the present invention is a resin composition containing a thermoplastic resin, starch, a plasticizer, and a lubricant, the starch and the plasticizer are mixed to plasticize the starch, and then the lubricant is mixed. Thus, it is possible to produce a resin composition in which the melt flow rate (MFR) of the resin composition at the time of melting is appropriately suppressed while appropriately expressing the function as a lubricant. By controlling the MFR of the resin composition at the time of melting, the resin composition can be easily subjected to extrusion molding or blow molding.
That is, according to the present invention, a method for producing a resin composition having excellent molding processability, a molded article, a film or a bag having excellent mechanical strength and good appearance using the resin composition obtained by the production method. A manufacturing method is provided.

It is a figure for demonstrating an example of the manufacturing method of a resin composition, and is a figure which shows the inside of the biaxial extruder 10 roughly. It is a figure for demonstrating an example of the manufacturing method of a resin composition, and is a figure which shows the inside of the twin-screw extruder 20 roughly. It is the schematic for demonstrating "the diameter D of a kneading disc."

Hereinafter, the present invention will be described. However, the present invention is not limited to the specific embodiments described below, and includes modifications that are arbitrarily modified within the technical scope of the present invention.
In this specification, the term “polymer” refers to a polymer composed of a single type of repeating structural unit (a so-called “homopolymer”) and a polymer composed of a plurality of types of repeating structural units (a so-called “polymer”). It is used as a concept including “copolymer”).
Moreover, in the following description, the partial structural unit of the 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”.

  The production method according to the present invention is a method for producing a resin composition containing a thermoplastic resin (A), starch (B), a plasticizer (C), and a lubricant (D), and comprises starch (B) and plastic A plasticizing step of mixing the agent (C) to plasticize the starch, and a lubricant mixing step of mixing the lubricant (D) after the plasticizing step. First, each raw material used for the manufacturing method according to the present invention will be described.

1. Resin composition 1.1. Thermoplastic resin (A)
As the thermoplastic resin (A) in the present invention, known thermoplastic resins can be widely applied. Examples thereof include polyester resins, polyethylene resins, polypropylene resins, polystyrene resins, polyvinyl chloride resins, and the like. In the present invention, the “system resin” includes the resin as a main component, and the main component means that the component is the most, and may include a component other than the main component. Absent. In the present invention, among these, polyester resins are preferably used, and the following aliphatic polyester resins and aliphatic oxycarboxylic acid resins are particularly preferably used. It is because it is decomposed by being buried in the soil, and it is possible to prevent global warming and prevent soil and air pollution.

1.1.1. Aliphatic polyester-based resin The aliphatic polyester-based resin is composed mainly of an aliphatic polyester. Specifically, an aliphatic polyester containing 50% by weight or more, preferably 60% by weight or more, and more preferably 70% by weight or more can be mentioned. The aliphatic polyester-based resin may contain components other than the aliphatic polyester. For example, the aliphatic polyester-based resin may have an aromatic polyester structure portion as a copolymer component in addition to the aliphatic polyester structure. It may be a mixture of resin and aromatic polyester resin or aromatic / aliphatic polyester resin. Specifically, the aliphatic polyester resin includes not only an aliphatic polyester composed of succinic acid (aliphatic dicarboxylic acid) and 1,4-butanediol (aliphatic diol), but also adipic acid and 1,4-cyclohexanedi It may be an aliphatic polyester having a cyclic structure composed of methanol (cyclic diol) or the like, and may contain an aliphatic polyester component having the cyclic structure as a copolymerization component. It may be a polymer alloy of an aliphatic polyester having a cyclic structure and an aliphatic polyester resin not having a cyclic structure. Alternatively, it may be an aromatic / aliphatic polyester containing terephthalic acid (aromatic dicarboxylic acid) as a copolymerization component, and an aliphatic polyester and an aromatic polyester and / or an aromatic / aliphatic polyester. It may be a polymer alloy.

(Aliphatic polyester resin)
The aliphatic polyester-based resin preferably includes a diol unit and a dicarboxylic acid unit, and more preferably, for example, a chain aliphatic and / or alicyclic diol unit represented by the following formula (1): The main component is an aliphatic polyester resin comprising a chain aliphatic and / or alicyclic dicarboxylic acid unit represented by the formula (2).

—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 formulas (1) and (2), “and” in the “divalent chain aliphatic hydrocarbon group and / or divalent alicyclic hydrocarbon group” means in one molecule of the constituent component. It may mean that both a divalent chain aliphatic hydrocarbon group and a divalent alicyclic hydrocarbon group may be included. Hereinafter, “chain aliphatic and / or alicyclic” may be simply abbreviated as “aliphatic”.

  Although the aliphatic diol component which gives the diol unit of Formula (1) is not particularly limited, 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. Specifically, for example, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like can be mentioned, among which 1,4-butanediol is particularly preferable. Two or more types of aliphatic diol components can be used.

  The aliphatic dicarboxylic acid component that gives 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 preferable. Particularly preferred. Specific examples of the aliphatic dicarboxylic acid component include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like, and succinic acid or adipic acid is particularly preferable. Two or more types of aliphatic dicarboxylic acid components can be used.

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

  As for the amount of the aliphatic oxycarboxylic acid component, the lower limit 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. , Preferably it is 20 mol% or less.

  In addition, the aliphatic polyester resin in the present invention includes “a trifunctional or higher aliphatic polyhydric alcohol”, “a trifunctional or higher aliphatic polyvalent carboxylic acid or acid anhydride thereof”, or “a trifunctional or higher aliphatic polyvalent alcohol”. Copolymerization of “oxycarboxylic acid” is preferred because the melt viscosity of the resulting aliphatic polyester resin can be increased.

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

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

  In addition, the trifunctional aliphatic oxycarboxylic acid component includes (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) one carboxyl group and two hydroxyl groups. Any type can be used. Specifically, malic acid or the like is preferably used. In addition, the tetrafunctional aliphatic oxycarboxylic acid 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 hydroxyl groups. It is divided into a type that shares a group in the same molecule, 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 generally 0 mol% or more, preferably 0.01 mol% or more, and the upper limit is usually 5 mol in all the components constituting the aliphatic polyester resin. % Or less, preferably 2.5 mol% or less.

  A preferred aliphatic polyester resin is a polybutylene succinate resin, a polybutylene succinate adipate resin, or a mixture thereof. That is, as the aliphatic polyester resin as the main component, polybutylene succinate, polybutylene succinate adipate, or a mixture thereof is particularly preferably used.

  The aliphatic polyester resin used in the present invention can be produced by a known method. For example, a general method of melt polymerization in which an esterification reaction and / or a transesterification reaction between the aliphatic dicarboxylic acid component and the aliphatic diol component is performed, followed by a polycondensation reaction under reduced pressure, Although it can manufacture also by the well-known solution heating dehydration condensation method using a solvent, the method of manufacturing by melt polymerization performed without a solvent from a viewpoint of economical efficiency or the simplicity of a manufacturing process is preferable.

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

(Aromatic / aliphatic polyester resin)
The aliphatic polyester-based resin may contain an aromatic / aliphatic polyester resin instead of the aliphatic polyester resin or in addition to the aliphatic polyester resin. The aromatic / aliphatic polyester resin is composed mainly of an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid, and an aromatic aliphatic copolymer polyester composed of an aliphatic diol. In this case, the content of the aromatic dicarboxylic acid unit is preferably 5 mol% or more and 60 mol% or less based on the total amount of the aliphatic dicarboxylic acid unit and the aromatic dicarboxylic acid unit (100 mol%). Specifically, for example, an aliphatic diol unit represented by the following formula (3), an aliphatic dicarboxylic acid unit represented by the following formula (4), and an aroma represented by the following formula (5) Group dicarboxylic acid unit as an essential component. However, it may have an aliphatic oxycarboxylic acid unit. Hereinafter, the aromatic / aliphatic polyester resin will be described.

—O—R ³ —O— (3)
[In the formula (3), R ³ represents a divalent chain aliphatic hydrocarbon group and / or a divalent alicyclic hydrocarbon group, and is not limited to one type when copolymerized. ]

—OC—R ⁴ —CO— (4)
[In the formula (4), R ⁴ represents a direct bond or a divalent chain aliphatic hydrocarbon group and / or a divalent alicyclic hydrocarbon group. It is not limited to species. ]

—OC—R ⁵ —CO— (5)
[In Formula (5), R ⁵ represents a divalent aromatic hydrocarbon group, and is not limited to one type when copolymerized. ]

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

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

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

  The aromatic / aliphatic polyester resin in the present invention may contain an aliphatic oxycarboxylic acid unit. Specific examples of the aliphatic oxycarboxylic acid component that gives an aliphatic oxycarboxylic acid unit include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 6-hydroxycaproic acid, and 2-hydroxy-3. , 3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-hydroxyisocaproic acid, or a mixture thereof. Furthermore, these lower alkyl esters or intramolecular esters may be used. When optical isomers are present in these, any of D-form, L-form and racemic form 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.

  As for the amount of the aliphatic oxycarboxylic acid component, the lower limit is usually 0 mol% or more, preferably 0.01 mol% or more, and the upper limit is usually 30 mol among all the components constituting the aromatic / aliphatic polyester resin. % Or less, preferably 20 mol% or less.

  The aromatic / aliphatic polyester resin can be produced by the same production method as that for the aliphatic polyester resin.

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

  The content of the aromatic / aliphatic polyester resin described above is preferably 1 part by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the aliphatic polyester resin. The lower limit of the content is more preferably 5 parts by weight or more, particularly preferably 10 parts by weight or more, and most preferably 20 parts by weight or more. The upper limit of the content is more preferably 70 parts by weight or less, particularly preferably 60 parts by weight or less. If the content of the aromatic / aliphatic polyester resin is too large, the stiffness of the film is insufficient, and it may be necessary to increase the thickness of the film for use as various packaging materials. On the other hand, if the content of the aromatic / aliphatic polyester resin is too small, the tensile elongation rate, tear strength, etc. may be insufficient.

1.1.2. Aliphatic oxycarboxylic acid resin In the present invention, an aliphatic oxycarboxylic acid resin can also be used as the thermoplastic resin (A). The aliphatic oxycarboxylic acid-based resin is mainly composed of an aliphatic oxycarboxylic acid composed of an aliphatic oxycarboxylic acid unit.

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

  The aliphatic oxycarboxylic acid-based resin may have an aliphatic oxycarboxylic acid unit derived from a tri- or higher functional aliphatic oxycarboxylic acid component. The trifunctional aliphatic oxycarboxylic acid component includes (i) a type having two carboxyl groups and one hydroxyl group in the same molecule, and (ii) a type having one carboxyl group and two hydroxyl groups. Both types can be used. Specifically, malic acid or the like is preferably used. In addition, the tetrafunctional aliphatic 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 hydroxyl groups. It is divided into a type that shares a group in the same molecule, 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 aliphatic oxycarboxylic acid resin may contain structural units derived from other components such as polyester as described above. The content of the other structural unit in the aliphatic oxycarboxylic acid-based resin is 100 mol% in total of the structural unit derived from the aliphatic oxycarboxylic acid and the other structural unit, and the lower limit is usually 0 mol% or more. Preferably it is 0.01 mol% or more, and an upper limit is 5 mol% or less normally, Preferably it is 2.5 mol% or less.

  In the resin composition in the present invention, the content of the thermoplastic resin (A) as described above is based on the total amount of the thermoplastic resin (A), starch (B) and plasticizer (C) described later. (100 parts by weight) is 20 parts by weight or more and 90 parts by weight or less, and the lower limit is preferably 30 parts by weight or more, more preferably 35 parts by weight or more, and the upper limit is preferably 80 parts by weight or less, more preferably 70 parts by weight. It is as follows. Here, if it is less than 20 parts by weight, film molding or injection molding may be difficult, and if it exceeds 90 parts by weight, the film tear strength may be insufficient.

1.2. Starch (B)
The starch (B) in the present invention is a carbohydrate (polysaccharide) having a molecular formula (C ₆ H ₁₀ O ₅ ) _n and is a natural polymer obtained by polymerizing a number of α-glucose molecules by glycosidic bonds or a modified product thereof. Here, “denaturation” includes all modifications such as chemical, physical and biological. Chemical modification indicates that some or all of the structural units of starch are modified by chemical reactions such as esterification, etherification, oxidation, reduction, coupling, dehydration, hydrolysis, dehydrogenation, halogenation, etc. In particular, it indicates that the hydroxyl group is etherified or esterified. Physical modification refers to changing physical properties such as changing the crystallinity. Biological degeneration refers to changing a chemical structure or the like using a living organism. Modified starch is easily plasticized and can be used particularly preferably in the present invention.

  Specific examples of the starch (B) in the present invention include corn starch, waxy corn starch, high amylose corn starch, wheat starch, rice starch, potato starch, sweet potato starch, tapioca starch, pea starch, and α starch. Corn starch or potato starch is preferred, and corn starch is particularly preferred.

  The amount of water contained in the starch (B) in the present invention is preferably 10 wt% or more, and particularly preferably 12 wt% or more. When the water content in the starch is 10 wt% or more, the starch is easily plasticized, the starch (B) can be uniformly dispersed in the resin composition, and it has excellent molding processability and mechanical strength. In addition, a more excellent resin composition can be obtained.

  The blending amount of the starch (B) is 5 parts by weight or more and 70 parts by weight based on the total amount (100 parts by weight) of the thermoplastic resin (A), the starch (B), and the plasticizer (C) described later. Or less, preferably 20 to 60 parts by weight, more preferably 25 to 50 parts by weight. Here, if the amount is less than 9 parts by weight, the effect of improving physical properties such as tear strength of the film may be insufficient. If the amount exceeds 70 parts by weight, water resistance, hydrolysis resistance, flexibility, and the like may be impaired. is there.

1.3. Plasticizer (C)
The plasticizer (C) in the present invention has an affinity for the starch (B) and is not particularly limited as long as it has a hydroxyl group. Specific examples thereof include water and monohydric alcohols. And organic compounds containing hydroxyl groups such as polyhydric 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 two or more organic compounds containing water and a hydroxyl group are used.
The molecular weight of the organic compound containing a hydroxyl group is preferably 3000 or less, more preferably 2500 or less, and particularly preferably 2000 or less.

  The compounding amount of the plasticizer (C) is 1 part by weight or more and 20 parts by weight based on the total amount (100 parts by weight) of the thermoplastic resin (A) and starch (B) and the plasticizer (C). The lower limit is preferably 3 parts by weight or more, more preferably 5 parts by weight or more, and the upper limit is preferably 15 parts by weight or less, more preferably 10 parts by weight or less. When content of a plasticizer (C) exceeds 20 weight part, there exists a possibility that a plasticizer (C) may bleed out from the film surface, or the elasticity modulus of the film obtained may fall. On the other hand, if the content of the plasticizer (C) is less than 1 part by weight, the starch (B) cannot be sufficiently plasticized and the dispersed particle size of the starch (B) may be coarse.

1.4. Lubricant (D)
The lubricant (D) in the present invention is not particularly limited as long as it can function as a lubricant. For example, ester lubricants such as butyl stearate, glycerol monostearate and glycerol monooleate; hydrocarbon lubricants such as liquid paraffin, paraffin wax and polyethylene wax; fatty acid lubricants such as stearic acid and oleic acid; stearyl alcohol and the like Higher alcohol lubricants; metal soap lubricants such as zinc stearate, calcium stearate and magnesium stearate; fatty acid amide lubricants such as unsaturated fatty acid amides having 6 to 30 carbon atoms and unsaturated fatty acid bisamides. Among these, Ester lubricants and fatty acid amide lubricants are preferred, and fatty acid amide lubricants are particularly preferred. When a fatty acid amide-based lubricant is used, the resin composition of the present invention has an appropriate slip property and anti-blocking property when formed into a molded body such as a film, and particularly has a good opening property when formed into a bag shape. .

  The compounding amount of the lubricant (D) is 0.001 part by weight or more and 1 part by weight with respect to the total amount (100 parts by weight) of the thermoplastic resin (A), starch (B) and plasticizer (C) described above. The lower limit is preferably 0.005 parts by weight or more, more preferably 0.01 parts by weight or more, and the upper limit is preferably 0.8 parts by weight or less, more preferably 0.5 parts by weight or less. If the content of the lubricant (D) exceeds 1 part by weight, the MFR of the resulting resin composition becomes excessively large, and the moldability may be impaired, or the surface of the obtained molded product may contain the lubricant (D). May bleed out and the appearance may be impaired. On the other hand, if the content of the lubricant (D) is less than 0.001 part by weight, the molded product may be blocked and the frictional resistance on the surface of the molded product may be increased.

1.5. Other components In the resin composition according to the present invention, a compatibilizing agent, an inorganic filler, a crystal nucleating agent, an antioxidant, an anti-blocking agent, an ultraviolet absorber, a light-resistant agent, an antioxidant, a heat stabilizer, a colorant , Flame retardants, mold release agents, antistatic agents, antifogging agents, surface wetting improvers, incineration aids, pigments, dispersion aids, surfactants, slip agents, hydrolysis inhibitors, end-capping agents, etc. Other components "may be used. These can be arbitrarily used as long as the effects of the present invention are not impaired.

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

  The compatibilizer is preferably added in an amount of 0.01 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the total amount of the thermoplastic resin (A), starch (B), and plasticizer (C) described above. .

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

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

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

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

  The amount of the inorganic filler contained in the resin composition of the present invention is not particularly limited, but is 100 parts by weight based on the total amount of the thermoplastic resin (A), starch (B), and plasticizer (C) described above. The inorganic filler is preferably 1 part by weight or more and 30 parts by weight or less. If the amount of the inorganic filler is too small, the effect of improving the mechanical properties may be reduced. On the other hand, if the amount is too large, the moldability and impact resistance may be deteriorated.

1.5.4. Various Additives Various conventionally known additives can be further added to the resin composition in the present invention. Additives include, for example, crystal nucleating agents, antioxidants, antiblocking agents, UV absorbers, light-resistant agents, heat stabilizers, colorants, flame retardants, mold release agents, antistatic agents, antifogging agents, surface wetting Examples include improvers, incineration aids, pigments, dispersion aids, various surfactants, slip agents, hydrolysis inhibitors, and the like. These may be used alone or in combination of two or more.

  The antifogging agent may be previously kneaded into the resin, or may be applied to the surface of the molded article after molding. Specifically, the antifogging agent used is preferably an ester surfactant of a saturated or unsaturated aliphatic carboxylic acid having 4 to 20 carbon atoms and a polyhydric alcohol.

  Examples of the anti-blocking agent include saturated fatty acid amides having 6 to 30 carbon atoms, saturated fatty acid bisamides, methylolamides, ethanolamides, natural silicas, synthetic silicas, synthetic zelites, and talcs.

  Examples of light-proofing agents include bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl-bis. (1,2,2,6,6-pentamethyl-4-piperidyl) malonate is preferred.

  As the ultraviolet absorber, a benzotriazole-based ultraviolet absorber is preferable, and 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (4,6- Diphenyl-1,3,5-triazin-2-yl) -5-hexyloxy-phenol is particularly preferred.

  As the antioxidant, a hindered phenol-based antioxidant is preferably used, and Irganox 3790 (1,3,5-tris [(4-tert-butyl-3-hydroxy-2,6-xylyl) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione), Irganox 1330 (3,3 ', 3 ", 5,5', 5" -hexa-tert-butyl -Α, α ', α "-(mesitylene-2,4,6-triyl) tri-p-cresol) is particularly preferred.

  The additive amount of these additives is usually 0.001 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the total amount of the thermoplastic resin (A), starch (B) and plasticizer (C) described above. It is.

  End-capping agents used mainly for the purpose of suppressing hydrolysis due to moisture in the atmosphere include carbodiimide compounds, epoxy compounds, oxazoline compounds, etc., among which have one or more carbodiimide groups in the molecule. Compounds (including polycarbodiimide compounds), and monocarbodiimide compounds such as dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, di-β- Examples include naphthyl carbodiimide. Of these, dicyclohexylcarbodiimide and diisopropylcarbodiimide, which are easily available industrially, are preferred.

2. Production method of resin composition according to the present invention The production method of the resin composition according to the present invention can be carried out using a conventionally known mixer / kneader. 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.

  Although the preparation method of a resin composition is not specifically limited, The method of melt-mixing the raw material which blended with the same extruder, the method of mixing after melt | dissolving with each separate extruder, etc. are mentioned. Moreover, it is also possible to obtain the molded body at the same time as preparing the resin composition by supplying each raw material directly to the molding machine. Examples include a method of adding and blending various additives, inorganic fillers, organic fillers, other resins, and the like when the components are mixed and melted by heating. At this time, blending oil or the like can also be used for the purpose of uniformly dispersing the various additives.

The resin composition obtained by the production method of the present invention has an MFR at the time of melting suppressed to an appropriate value and has excellent molding processability, and has a mechanical strength and appearance of a molded product obtained by molding. It will be excellent. In order to obtain such a resin composition, in the present invention, the starch (B) and the plasticizer (C) are mixed to plasticize the starch, and the lubricant (D) after the plasticization step. And a lubricant mixing step. More specifically, for example, by mixing each component as in any of the following (I) to (III), a resin composition having excellent molding processability can be appropriately produced.
(I) After the step (plasticization step I-1) of mixing starch (B) and plasticizer (C) to plasticize starch (B) to obtain a starch composition, and Prior to the step of mixing the starch composition and the thermoplastic resin (A) (resin mixing step I-3), the starch composition and the lubricant (D) are mixed (lubricant mixing step I-2).
(II) After starch (B) and plasticizer (C) are mixed to plasticize starch (B) to form a starch composition (plasticization step II-1), the starch composition; The thermoplastic resin (A) containing the lubricant (D) is mixed (lubricant mixing step II-2).
(III) A step (plasticization step III-1) in which starch (B) and plasticizer (C) are mixed to plasticize starch (B) to form a starch composition, and the starch composition and heat After the step of mixing the plastic resin (A) (resin mixing step III-2), the lubricant (D) is then mixed (lubricant mixing step III-3).

  First, the case where the resin composition which concerns on this invention is manufactured according to process I-1-3 is demonstrated.

2.1.1. Process I-1 (plasticization process)
In Step I-1, starch (B) and plasticizer (C) are mixed while adjusting the shearing force applied by the mixer, the mixing time, and the temperature at the time of mixing. In particular, it is preferable that the resin temperature during mixing be higher than 80 ° C. For example, as shown in FIG. 1, using a twin-screw extruder 10 provided with screw extrusion parts 1a, 1b, 1c and kneading disk parts 2a, 2b, 2c in a casing 5, starch (B) and The case where it mixes with a plasticizer (C) is demonstrated. In the twin-screw extruder 10, a supply port (not shown) for supplying starch (B) and a plasticizer (C) to the root portion (left side portion in FIG. 1) of the screw extrusion portion 1 a of the housing 5. ) Is provided, from which the starch (B) and the plasticizer (C) are fed into the extruder and extruded to the kneading disk portion 2a. Then, by applying a predetermined shearing force at the kneading disk portion 2a, the starch (B) and the plasticizer (C) are mixed, and the starch (B) is plasticized to form a starch composition. The starch composition obtained through the step I-1 is usually in a gelatinized state. In FIG. 1, the starch composition is extruded to the screw extruding part 1 b in order to continue the process I-2 in the same twin-screw extruder 10.

Here, the starch (B) can be easily plasticized by adjusting the resin temperature in the kneading disk portion 2a to be higher than 80 ° C. Moreover, when plasticizing, it is preferable to make resin temperature into 200 degrees C or less. When the temperature is higher than that, the color tone of the molded product may be impaired due to the coloration of starch due to thermal deterioration, and the mechanical properties of the molded product may be impaired.
The kneading shape is not particularly specified as long as the resin temperature is within the above specified range, so-called forward feed shape (shape that gives the force in the same direction to the flow direction), reverse feed shape (in the flow) The shape in which the mixture gives a force in the opposite direction) may be used.
Further, the kneading disk part may be composed of a plurality of blocks (that is, a so-called feeding part may be provided between the plurality of kneading disk parts), The kneading disk portion may be configured by combining kneading in a reverse feed shape as appropriate. In this case, the “total length L in the flow direction of the kneading disk portion” means the total length of the blocks in the flow direction. The “kneading disc diameter D” means the diameter of the kneading disc. In the case of a biaxial extruder, as shown in FIG. 3, the diameter of the kneading disc provided on one axis is the diameter D of the kneading disc in the cross section in the direction orthogonal to the flow direction.
Further, if the L / D value of the kneading disk (the value obtained by dividing the flow direction length L of the kneading disk portion (see FIG. 1) by the diameter D of the kneading disk (see FIG. 1)) is large, As a result of applying a shearing force for a long time in the disk portion 2a, plasticization of starch is promoted. Thus, starch (B) can be easily plasticized also by adjusting the form of the kneading disc part 2a suitably.

  In addition, when there are two or more types of thermoplastic resins (A) used in the present invention, at least one of them can be added in Step I-1.

  Moreover, you may use mixing means other than the above extruders, for example, well-known mixers, such as a super mixer, a Henschel mixer, and a Hobart mixer. Even in this case, the starch (B) is mixed while being plasticized with the plasticizer (C) by adjusting the rotational speed so that the mixture temperature at the time of mixing is higher than 80 ° C. A composition can be obtained.

2.1.2. Step I-2 (lubricant mixing step)
Step I-2 is a step of mixing the starch composition obtained in Step I-1 and the lubricant (D). What is necessary is just to adjust suitably the compounding ratio of a starch composition and a lubricant (D) so that it may become a compounding ratio as mentioned above in the resin composition after manufacture. Moreover, you may use the masterbatch mixed with the thermoplastic resin (A) as a lubricant (D).

  For example, in the twin-screw extruder 10 as shown in FIG. 1, a supply port for supplying the lubricant (D) to the root portion (left side portion of FIG. 1) of the screw extrusion portion 1 b of the housing 5. (Not shown) is provided, from which the lubricant (D) is fed into the extruder and extruded to the kneading disk portion 2b together with the starch composition. Then, the starch composition and the lubricant (D) are mixed by applying a predetermined shearing force at the kneading disk portion 2b. In step I-2, there is no particular limitation on the mixing temperature, the shape of the kneading disk, and the L / D value of the kneading disk. For example, the temperature may be 80 ° C. or more and 200 ° C. or less, and the kneading disk L / D value may be about 0.5 to 15. In FIG. 1, the mixture is pushed out to the screw extruding part 1 c in order to continue the process I-3 in the same twin-screw extruder 10.

  Step I-2 can also be performed using the mixing means other than the extruder.

2.1.3. Step I-3 (resin mixing step)
Step I-3 is a step of mixing the mixture obtained in Step I-2 and the thermoplastic resin (A). At this time, it is preferable to mix under a temperature condition higher than the melting point of the thermoplastic resin (A). What is necessary is just to adjust suitably the compounding ratio of a mixture and a thermoplastic resin (A) so that it may become a compounding ratio as mentioned above in the resin composition after manufacture.

  For example, in the twin-screw extruder 10 as shown in FIG. 1, supply for supplying the thermoplastic resin (A) to the root portion (left side portion of FIG. 1) of the screw extrusion portion 1 c of the housing 5. A port (not shown) is provided, from which the thermoplastic resin (A) is supplied to the inside of the extruder, and extruded to the kneading disk portion 2c together with the mixture. Then, by applying a predetermined shearing force at the kneading disk portion 2c, the mixture and the thermoplastic resin (A) are mixed to form a resin composition. Here, for example, the kneading disk portion 2c is heated to a temperature higher than the melting point of the thermoplastic resin (A), so that the mixture and the thermoplastic resin (A) are mixed with the thermoplastic resin (A ) Can be mixed under a temperature condition higher than the melting point. In Step I-3, by setting the mixing temperature to be higher than the melting point of the thermoplastic resin (A), the resin composition can be continuously used for molding. In Step I-3, the shape of the kneading disk and the L / D value of the kneading disk are not particularly limited. For example, the temperature may be 80 ° C. or higher and 200 ° C. or lower, and the kneading disk L / D value may be about 0.5 to 15.

  Step I-3 can also be performed using the mixing means other than the extruder. Even in this case, the inside of the mixer is heated so that the mixture and the thermoplastic resin (A) are mixed under a temperature condition higher than the melting point of the thermoplastic resin (A). Is preferred.

  In addition, as long as the process I-1, I-2, I-3 is a range which does not deviate from the content as described above, the embodiment is not specifically limited. For example, all of the steps I-1, I-2, and I-3 may be performed in the same extruder, or after the step I-1 is performed in a certain extruder, the steps I-2 and I-3 are performed. You may implement in another extruder.

  Next, the case where the resin composition which concerns on this invention is manufactured by process II-1 and II-2 is demonstrated.

2.2.1. Process II-1 (plasticization process)
Step II-1 is the same step as Step I-1. That is, the gelatinized starch composition may be obtained in the same manner as in Step I-1.

2.2.2. Step II-2 (lubricant mixing step)
In Step II-2, the starch composition obtained in Step II-1 and the thermoplastic resin (A) containing the lubricant (D) (hereinafter may be referred to as “resin (D / A)”). It is a process of mixing. In mixing, it is preferable to mix under a temperature condition higher than the melting point of the thermoplastic resin (A). What is necessary is just to adjust suitably the compounding ratio of a starch composition and resin (D / A) so that it may become the above compounding ratio in the resin composition after manufacture.

  The resin (D / A) can be easily obtained by mixing the lubricant (D) and the thermoplastic resin (A) by a known mixing means. The form may be liquid or solid such as pellets.

  For example, the case where a resin composition is manufactured using the twin-screw extruder 20 as shown in FIG. 2 will be described. The biaxial extruder 20 has the same configuration as the biaxial extruder 10 except that the screw extruder 1c and the kneading disk portion 2c are not provided. In the twin-screw extruder 20, a supply port (not shown) for supplying resin (D / A) is provided at the root portion of the screw extrusion portion 1 b of the housing 5 (the left side portion in FIG. 1). From here, the resin (D / A) is supplied into the extruder and is extruded to the kneading disk portion 2b together with the starch composition. Then, when a predetermined shearing force is applied at the kneading disk portion 2b, the starch composition and the resin (D / A) are mixed to form a resin composition. Here, for example, by heating the kneading disk portion 2b so as to be higher than the melting point of the thermoplastic resin (A), the starch composition and the resin (D / A) are converted into the thermoplastic resin (D / A). Mixing can be performed under temperature conditions higher than the melting point of A). In Step II-2, by setting the mixing temperature to be higher than the melting point of the thermoplastic resin (A), the resin composition can be continuously used for molding. In Step II-2, the shape of the kneading disk and the L / D value of the kneading disk are not particularly limited. For example, the temperature may be 80 ° C. or higher and 200 ° C. or lower, and the kneading disk L / D value may be about 0.5 to 15.

  Step II-2 can also be performed using the mixing means other than the extruder. Even in this case, the inside of the mixer is heated so that the starch composition and the resin (D / A) are mixed under a temperature condition higher than the melting point of the thermoplastic resin (A). It is preferable.

  Moreover, as long as the process II-1 and II-2 are the range which does not deviate from the content described above, the embodiment will not be specifically limited, For example, all the process II-1 and II-2 are implemented in the same extruder. Alternatively, after step II-1 is carried out in one extruder, step II-2 may be carried out in another extruder.

  Finally, the case where the resin composition according to the present invention is produced through steps III-1 to III-3 will be described.

2.3.1. Process III-1 (plasticization process)
Step III-1 is the same as Step I-1 and Step II-1. That is, the starch composition gelatinized like the process I-1 or the process II-1 should just be obtained.

2.3.2. Step III-2 (resin mixing step)
Step III-2 is a step of mixing the starch composition obtained in Step III-1 and the thermoplastic resin (A). At this time, it is preferable to mix under a temperature condition higher than the melting point of the thermoplastic resin (A). What is necessary is just to adjust suitably the compounding ratio of a starch composition and a thermoplastic resin (A) so that it may become the above compounding ratio in the resin composition after manufacture.

  For example, in the twin-screw extruder 10 as shown in FIG. 1, supply for supplying the thermoplastic resin (A) to the root portion (left side portion of FIG. 1) of the screw extrusion portion 1 b of the housing 5. A port (not shown) is provided, from which the thermoplastic resin (A) is supplied into the extruder and extruded to the kneading disk portion 2b together with the starch composition. Then, the starch composition and the thermoplastic resin (A) are mixed by applying a predetermined shearing force at the kneading disk portion 2b. Here, for example, the kneading disk portion 2b is heated so as to have a temperature higher than the melting point of the thermoplastic resin (A), whereby the mixture and the thermoplastic resin (A) are mixed with the thermoplastic resin (A ) Can be mixed under a temperature condition higher than the melting point. In Step III-2, by setting the mixing temperature to be higher than the melting point of the thermoplastic resin (A), the resin composition can be continuously subjected to molding through Step III-3. In Step III-2, the shape of the kneading disk and the L / D value of the kneading disk are not particularly limited. For example, the temperature may be 80 ° C. or higher and 200 ° C. or lower, and the kneading disk L / D value may be about 0.5 to 15.

  Step III-2 can also be performed using the mixing means other than the extruder. Even in this case, the inside of the mixer is heated so that the starch composition and the thermoplastic resin (A) are mixed under a temperature condition higher than the melting point of the thermoplastic resin (A). It is preferable to keep it.

2.3.3. Process III-3 (lubricant mixing process)
Step III-3 is a step of mixing the mixture obtained in Step III-2 with the lubricant (D). At this time, it is preferable to mix under a temperature condition higher than the melting point of the thermoplastic resin (A). What is necessary is just to adjust suitably the mixture ratio of a mixture and a lubricant (D) so that it may become a mixture ratio as mentioned above in the resin composition after manufacture. As the lubricant (D), a master batch mixed with the thermoplastic resin (A) may be used.

  For example, in the twin-screw extruder 10 as shown in FIG. 1, a supply port for supplying the lubricant (D) to the root portion (left side portion of the paper in FIG. 1) of the screw extrusion portion 1 c of the housing 5. (Not shown) is provided, from which the lubricant (D) is supplied to the inside of the extruder and is extruded together with the mixture to the kneading disk portion 2c. Then, by applying a predetermined shearing force at the kneading disk portion 2c, the mixture and the lubricant (D) are mixed to form a resin composition.

Step III-3 can also be performed using the mixing means other than the extruder. Even in this case, it is preferable to heat the inside of the mixer so that the mixture and the lubricant (D) are mixed under a temperature condition higher than the melting point of the thermoplastic resin (A).
For example, it is preferable that the steps up to Step III-2 are performed in the same extruder, and Step III-3 is performed in an extruder attached to the molding machine.

  Further, the embodiments of the processes III-1, III-2, and III-3 are not particularly limited as long as the contents do not deviate from the contents described above. For example, all of Steps III-1, III-2, and III-3 may be performed in the same extruder, or only Steps III-1 and III-2 are performed in a certain extruder, and then Step III-3 is performed. May be carried out in a separate extruder.

  Thus, in the manufacturing method according to the present invention, the starch (B) and the plasticizer (C) are mixed, and after the starch (B) is plasticized, the lubricant (D) is mixed. By mixing in such an order, the melt flow rate at the time of melting of the resin composition is suppressed to a predetermined value or less. The reason can be considered as follows.

That is, when plasticizing the starch (B) with the plasticizer (C) or mixing the lubricant (D) before plasticizing, the lubricant (D) is present on the surface of the starch (B). Thus, it is considered that the plasticizer (C) is less likely to enter the starch (B). It is also conceivable that the presence of the lubricant (D) reduces the friction on the surface of the starch (B) and a desired shear force cannot be applied. If it does so, starch (B) will not be plasticized well but it will be thought that solid starch (B) and a plasticizer (C) will mutually separate. In such a case, the starch (B) and the plasticizer (C) are separated and dispersed in the resin composition even if the resin composition is melt-mixed together with the thermoplastic resin (A). It is considered that the starch (B) cannot be uniformly dispersed in the resin composition. As a result, the melt flow rate at the time of melting the resin composition is remarkably increased, and the resin composition cannot be successfully subjected to molding. Alternatively, since the starch is not sufficiently plasticized, a large number of starch-derived agglomerates are present in the resin composition, causing problems during the molding process, and mechanical properties of the molded product are greatly impaired.
On the other hand, in the production method according to the present invention, since the lubricant (D) is mixed after the starch (B) is appropriately plasticized, the above problems do not occur. Therefore, according to the present invention, it is possible to produce a resin composition having excellent moldability.

3. Molded body The resin composition according to the present invention can be used for molding by various molding methods applied to general-purpose plastics. The molding methods include, for example, compression molding (compression molding, laminate molding, stampable molding), injection molding, extrusion molding and coextrusion molding (film molding by inflation method or T-die method, laminate molding, pipe molding, electric wire / cable molding. , Profile molding), hollow molding (various blow molding), calendar molding, foam molding (melt foam molding, solid phase foam molding), solid molding (uniaxial stretching molding, biaxial stretching molding, roll rolling molding, stretch oriented nonwoven fabric Examples 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.). Among these, extrusion molding, injection molding, foam molding, and hollow molding are preferably applied. As a specific shape, application to a film, a container and a fiber is preferable. Since the resin composition of the present invention has good melting characteristics and mechanical properties, it is preferably used for a product produced from a film formed by inflation molding, and further from a film formed by inflation molding.

  When the resin composition according to the present invention is formed into a film, the film has an Elmendorf tear strength according to JIS K7128, preferably 10 N / mm or more, more preferably 20 N / mm or more, particularly preferably 30 N / mm or more. It is.

4). Applications The resin composition according to the present invention is suitably used in a wide range of applications such as liquids and powders for various foods, medicines, miscellaneous goods, solid packaging materials, agricultural materials, and building materials. Specific applications include injection molded products (for example, fresh food trays, fast food containers, outdoor leisure products, etc.), extruded products (films, such as fishing lines, fishing nets, vegetation nets, water retaining sheets, etc.), hollow molding. Products (bottles, etc.), other agricultural films, coating materials, fertilizer coating materials, laminate films, plates, stretched sheets, monofilaments, non-woven fabrics, flat yarns, staples, crimped fibers, striped tape, Examples include split yarns, composite fibers, blow bottles, foams, shopping bags, garbage bags, compost bags, and the like.

  Since the resin composition of the present invention has good moldability and mechanical strength, it is preferably applied to a shopping bag or a garbage bag produced from a film formed by inflation molding.

  In addition, packaging materials such as packaging films, bags, trays, bottles, cushioning foams, fish boxes, etc., and agricultural materials such as mulching films, tunnel films, house films, sun covers, grass protection sheets, etc. , Cocoon sheets, germination sheets, vegetation mats, nursery beds, flower pots and the like.

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. Physical property evaluation [1.1. Resin fluidity evaluation]
The flowability (melt flow rate, MFR) at the time of melting of the obtained starch resin composition was measured under the conditions of 160 ° C. and 5 kg load according to JIS K7210.

[1.2. Evaluation of film formability]
The ease of molding when performing inflation molding was evaluated according to the following criteria.
○: Good. At a predetermined temperature (150 ° C.), it can be molded to a predetermined thickness (20 μm), and there is no molding trouble due to perforation or the like.
Δ: Somewhat problematic. Although it is possible to mold to a predetermined thickness (20 μm) at a predetermined temperature (150 ° C.), a molding trouble due to perforation or the like occasionally occurs.
X: Defect. Molding troubles due to perforations occur frequently, and it is impossible to mold to a predetermined thickness (20 μm) at a predetermined temperature (150 ° C.).

[1.3. Appearance evaluation of film]
A sample was cut out in a size of 30 cm × 30 cm from the film subjected to inflation molding, and the appearance was evaluated by visually counting the number of foreign substances (aggregates) contained in the sample. Evaluation was performed according to the following criteria.
○: Good. The number of foreign matters (aggregates) contained in the sample is less than 10.
Δ: Somewhat problematic. The number of foreign substances (aggregates) contained in the sample is 10 or more and less than 30.
X: Defect. The number of foreign substances (aggregates) contained in the sample is 30 or more.

[1.4. Mechanical strength of film]
<1.4.1. Measuring method of tear strength>
Elmendorf tear strength was measured in accordance with JIS K7128.

<1.4.2. 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.

2. Used thermoplastic resin etc. [2.1. Thermoplastic resin (A)]
The following resins were used as the thermoplastic resin (A).
(A-1) GS Pla (AD92WN): polybutylene succinate adipate (Mitsubishi Chemical Corporation)
(A-2) Ecoflex (FBX7001): polybutylene adipate terephthalate (manufactured by BASF)

[2.2. Starch (B)]
The following corn starch was used as a starch not subjected to any chemical modification.
(B-1) Y-3P (Nippon Cornstarch Co., Ltd .; moisture content 12.0%)
The following corn starch was used as the physically modified starch (pregelatinized corn starch).
(B-2) Mold No. 1 (Nippon Cornstarch)

[2.3. Plasticizer (C)]
As a plasticizer, glycerin (manufactured by Shin Nippon Chemical Co., Ltd .; concentrated glycerin S) was used.

[2.4. (D) Acid amide compound]
As the acid amide compound, erucic acid amide (manufactured by NOF Corporation; Alflow P-10) was used.

<Production example>
As shown in Table 1 below, 100 parts by weight of an aliphatic polyester resin (A-1) and 5 parts by weight of an acid amide compound (D) were blended, and a screw type twin screw extruder (Technobel's twin screw extruder (KZW15) was blended. )) From a hopper and kneaded so that the maximum temperature is 190 ° C. or less, to obtain a resin composition (X-1). The pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.

<Example 1>
As shown in Table 1 below, 35 parts by weight of starch (B-1) and 18 parts by weight of aromatic / aliphatic polyester resin (A-2) were mixed with a screw-type twin-screw extruder (TEX30; 22 manufactured by Nippon Steel Works). Cylinder, L / D = 77) is supplied to the hopper, 9 parts by weight of the plasticizer (C) is press-fitted from the upper part of the extruder cylinder, and after being mixed so that the resin temperature becomes 170 ° C. or less, the vent part Then, 38 parts by weight of aliphatic polyester resin (A-1) is supplied from the side feeder, and the maximum temperature of starch, plasticizer, thermoplastic resin, and aliphatic polyester resin is 170 ° C. The mixing process is performed sequentially in the same extruder, suction is performed by a vacuum vent, the resin composition is extruded in a strand form from a die, cooled in a water tank, and then cut. To give a white starch-containing resin composition (Y-1). The set temperature during kneading was 30 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.

  4 parts by weight of resin composition (X-1) is added to 100 parts by weight of resin composition (Y-1), blended, and then charged into a hopper of an inflation molding machine (Empura Sangyo Co., Ltd .; E30SP). Carried out. The molding temperature was 150 ° C. and the blow ratio was 2.5. The film thickness was 20 microns. The appearance of the film was good with no lumpy aggregates. Further, the opening of the obtained film was very good because it was possible to open the mouth without any particular trouble. Tables 2 and 3 show the mechanical properties of the obtained film.

<Example 2>
As shown in Table 1 below, in the production of the starch-containing resin composition of Example 1, 38 parts by weight of aliphatic polyester resin (A-1) and acid amide compound (D) 0. Extrusion was carried out in the same manner except that the mixture was 2 parts by weight to obtain a white starch-containing resin composition (Y-2). Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.

  Inflation molding was performed under the same conditions as in Example 1 using the obtained resin composition (Y-2). The appearance of the film was good with no lumpy aggregates. Further, the opening of the obtained film was very good because it was possible to open the mouth without any particular trouble. Tables 2 and 3 show the mechanical properties of the obtained film.

<Example 3>
As shown in Table 1 below, in the production of the starch-containing resin composition of Example 2, extrusion was carried out in the same manner except that the amount of the acid amide compound (D) to be added was 0.6 parts by weight. A starch-containing resin composition (Y-3) was obtained. Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.

  Inflation molding was performed under the same conditions as in Example 1 using the obtained resin composition (Y-3). The appearance of the film was good with no lumpy aggregates. Further, the opening of the obtained film was very good because it was possible to open the mouth without any particular trouble. Tables 2 and 3 show the mechanical properties of the obtained film.

<Example 4>
As shown in Table 1 below, 30 parts by weight of starch (B-1) and 21 parts by weight of aromatic / aliphatic polyester resin (A-2) were mixed with a screw-type twin-screw extruder (TEX30; 22 manufactured by Nippon Steel Works). Cylinder, L / D = 77) is supplied to the hopper, 9 parts by weight of the plasticizer (C) is press-fitted from the upper part of the extruder cylinder, and after being mixed so that the resin temperature becomes 170 ° C. or less, the vent part Then, water vapor is removed, and subsequently, 40 parts by weight of aliphatic polyester resin (A-1) and 0.2 part by weight of acid amide compound (D) are supplied from the side feeder, and starch, plasticizer, and thermoplastic resin are supplied. , And the step of mixing the aliphatic polyester resin so that the maximum temperature is 170 ° C. or less is sequentially performed in the same extruder, sucked by a vacuum vent, and the resin composition is pushed from the die into a strand shape. And, then cutting after cooling in a water bath to give white starch-containing resin composition (Y-4). The set temperature during kneading was 30 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.

  Inflation molding was carried out under the same conditions as in Example 1 using the resin composition (Y-4). The appearance of the film was good with no lumpy aggregates. Further, the opening of the obtained film was very good because it was possible to open the mouth without any particular trouble. Tables 2 and 3 show the mechanical properties of the obtained film.

<Example 5>
As shown in Table 1 below, in the production of the starch-containing resin composition of Example 2, extrusion was carried out in the same manner except that 35 parts by weight of starch (B-2) was added from the hopper, and white starch was used. The containing resin composition (Y-5) was obtained. The set temperature during kneading was 30 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.

  Inflation molding was performed under the same conditions as in Example 1 using the obtained resin composition (Y-5). The appearance of the film was good with no lumpy aggregates. Further, the opening of the obtained film was very good because it was possible to open the mouth without any particular trouble. Tables 2 and 3 show the mechanical properties of the obtained film.

<Comparative Example 1>
As shown in Table 1 below, 35 parts by weight of starch (B-1), 18 parts by weight of aromatic / aliphatic polyester resin (A-2) and 0.2 parts by weight of acid amide compound (D) Supply to the hopper of a shaft extruder (TEX30 manufactured by Nippon Steel Works; 22 cylinders, L / D = 77), and 9 parts by weight of plasticizer (C) is press-fitted from the top of the extruder cylinder, so that the resin temperature is 170 ° C. or lower. After passing through the mixing step, water vapor is removed at the vent, and subsequently 38 parts by weight of the aliphatic polyester resin (A-1) is supplied from the side feeder, and starch, plasticizer, and thermoplastic resin are supplied. And the step of mixing the aliphatic polyester resin so that the maximum temperature is 170 ° C. or less, sequentially in the same extruder, suction by a vacuum vent, the resin composition from the die to the strand And out, and cutting after cooling in a water bath to give white starch-containing resin composition (Y-6). The set temperature during kneading was 30 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.

  Inflation molding was performed under the same conditions as in Example 1 using the obtained resin composition (Y-6). The molten film at the time of molding was shaken and unstable, and the thickness and width of the resulting film varied. Although the opening property of the film was good, there were some aggregates that seemed to be derived from starch. A portion having a thickness of about 20 microns was selected from the obtained film, and the mechanical properties of the film were evaluated. Tables 2 and 3 show the mechanical properties of the obtained film.

<Comparative example 2>
As shown in Table 1 below, in Comparative Example 1, except that the starch introduced from the hopper was starch (B-2), extrusion was carried out in the same manner to obtain a white starch-containing resin (Y-7). . Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.

  Inflation molding was carried out under the same conditions as in Example 1 using the obtained resin composition (Y-7). Similar to Comparative Example 1, the melted film was shaken and unstable during molding, and the thickness and width of the resulting film varied. Although the opening property of the film was good, there were some aggregates that seemed to be derived from starch. A portion having a thickness of about 20 microns was selected from the obtained film, and the mechanical properties of the film were evaluated. Tables 2 and 3 show the mechanical properties of the obtained film.

<Comparative Example 3>
Starch (B-1) was charged into a speed dryer (manufactured by Matsui Seisakusho, model PO-120), and dried at 100 ° C. for 2 hours under a nitrogen stream to obtain starch (B-3). It was 9% when the moisture content of the starch (B-3) was measured.
And as shown in the following Table 1, in Comparative Example 1, extrusion was carried out in the same manner except that the starch introduced from the hopper was starch (B-3) to obtain a white starch-containing resin (Y-8). . Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.

  Inflation molding was performed under the same conditions as in Example 1 using the obtained resin composition (Y-8). Many agglomerates (foreign matter) were found in the molten film at the time of molding, and the molten film could not be expanded with air to a predetermined blow ratio.

<Comparative example 4>
Except that the amount of acid amide (D) added from the hopper was 1.5 parts by weight in Comparative Example 1, extrusion was carried out in the same manner to obtain a white starch-containing resin (Y-9). Thereafter, the pellets of the resin composition were dried at 60 ° C. in a nitrogen atmosphere for 8 hours.

  The obtained resin composition (Y-9) was used to perform inflation molding under the same conditions as in Example 1. However, the molten resin could not be drawn upward and adhered to the die (drawdown). Therefore, inflation molding could not be performed.

  From the results of Tables 2 and 3, when the film was molded using the resin composition according to the example, compared with the case where the film was molded using the resin composition according to the comparative example, film moldability and film appearance In addition, the mechanical properties such as yield strength, breaking strength, breaking elongation, and Elmendorf tear strength are all excellent. That is, according to the method for producing a resin composition according to the present invention, a resin composition excellent in molding processability can be provided. And it can be said that the film etc. which are excellent in a mechanical physical property and an external appearance can be obtained by shape | molding such a resin composition.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein. The invention can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and the resin composition, molded article, film, and bag manufacturing method accompanying such changes are also included in the present invention. Should be understood as being included in the technical scope of

  The resin composition obtained by the production method according to the present invention and the molded product thereof are excellent in mechanical properties, such as various foods, medicines, powders for miscellaneous goods, solid packaging materials, agricultural materials, building materials, etc. It is widely used.

Claims (9)

A method for producing a resin composition containing a thermoplastic resin (A), starch (B), plasticizer (C), and lubricant (D),
A plasticizing step of mixing the starch (B) and the plasticizer (C) to plasticize the starch;
A lubricant mixing step of mixing the lubricant (D) after the plasticizing step;
A method for producing a resin composition, comprising:   The method for producing a resin composition according to claim 1, wherein the amount of water contained in the starch (B) is 10 wt% or more.   The method for producing a resin composition according to claim 1 or 2, wherein the starch (B) is modified.   The method for producing a resin composition according to any one of claims 1 to 3, wherein the lubricant (D) is a fatty acid amide lubricant.   The method for producing a resin composition according to any one of claims 1 to 4, wherein the plasticizer (C) is an organic compound having a hydroxyl group.   The method for producing a resin composition according to any one of claims 1 to 5, wherein the thermoplastic resin (A) is an aliphatic polyester resin.   The manufacturing method of a molded object provided with the process of shape | molding the resin composition obtained by the manufacturing method of the resin composition of any one of Claims 1-6.   The manufacturing method of a film provided with the process of shape | molding the resin composition obtained by the manufacturing method of the resin composition of any one of Claims 1-6.   The manufacturing method of a bag provided with the process of further shape | molding the film obtained by the manufacturing method of the film of Claim 8.

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