Composition, emulsion, method for producing emulsion, and molded product

Abstract

The present invention provides a composition that exhibits excellent emulsification properties, good fluidity when formed into an emulsion, and a molded product obtained by drying the emulsion that exhibits excellent water resistance and excellent shape retention, an emulsion containing the composition, a method for producing the emulsion containing the composition, and a molded product containing the composition. [Solution] A composition comprising an aliphatic polyester (A), polyvinyl alcohol (B), and a crosslinking agent (C), wherein the aliphatic polyester (A) contains units derived from aliphatic diol (a1-1) and aliphatic dicarboxylic acid (a1-2), and has an acid value of 10KOH mg / g or less, the content of units derived from aromatic dicarboxylic acid in the aliphatic polyester (A) is 20% by mass or less, and the content of the crosslinking agent (C) is 10 to 100 parts by mass per 100 parts by mass of the polyvinyl alcohol (B).

Description

Technical Field

[0001] The present invention relates to a composition, an emulsion, a method for producing an emulsion, and a molded article.

Background Art

[0002] In recent years, the development of aqueous dispersions and aqueous solutions containing water-soluble polymers such as polyester resins and polyvinyl alcohol has been actively carried out. Such aqueous dispersions and aqueous solutions have a high possibility of being applied to a wide range of fields such as the paint field, the adhesive field, the printing field, the fiber field, and the film field, and are being studied in various fields.

[0003] As such technologies, for example, Patent Documents 1 to 3 have been proposed. Patent Document 1 discloses a biodegradable aqueous dispersion comprising a biodegradable polyester resin, a biodegradable emulsifier, and a crosslinking agent. Patent Document 2 discloses a resin composition containing polyvinyl alcohol and a polyester having a carboxyl group and / or a salt of a carboxyl group as a substituent. Patent Document 3 discloses an emulsion containing a specific block copolymer and a dispersant.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] While many aqueous dispersions and aqueous solutions containing polyester resins and water-soluble polymers have been reported conventionally, there is a need for a product that is easier to manufacture, easier to handle, and exhibits superior water resistance and shape retention when molded.

[0006] The present invention has been made to solve the aforementioned problems, and aims to provide a composition that is easy to emulsify, exhibits excellent fluidity when formed into an emulsion, and in which a molded product obtained by drying the emulsion exhibits excellent water resistance and excellent shape retention, an emulsion containing the composition, a method for producing the emulsion containing the composition, and a molded product containing the composition. [Means for solving the problem]

[0007] As a result of diligent research to solve the above problems, the inventors of the present invention have come up with the following invention and found that it can solve the problems. In other words, the present invention is as follows.

[0008] [1] A composition containing an aliphatic polyester (A), polyvinyl alcohol (B), and a crosslinking agent (C), The aliphatic polyester (A) contains units derived from an aliphatic diol (a1-1) and an aliphatic dicarboxylic acid (a1-2), and has an acid value of 10KOH mg / g or less. The aliphatic polyester (A) contains 20% by mass or less of units derived from aromatic dicarboxylic acids. A composition in which the crosslinking agent (C) is contained in an amount of 10 to 100 parts by mass per 100 parts by mass of polyvinyl alcohol (B). [2] The composition according to [1], wherein the content of the polyvinyl alcohol (B) is 1 to 50 parts by mass per 100 parts by mass of the aliphatic polyester (A). [3] The composition according to [1] or [2] above, wherein the aliphatic diol (a1-1) is a diol having a branched chain. [4] The composition according to any one of [1] to [3] above, wherein the aliphatic diol (a1-1) is a diol having a methyl group as a branched chain. [5] The composition according to any one of [1] to [4] above, wherein the two hydroxyl groups of the aliphatic diol (a1-1) are primary hydroxyl groups. [6] The composition according to any one of [1] to [5] above, wherein the aliphatic diol (a1-1) does not have a quaternary carbon. [7] The aliphatic polyester (A) is a block copolymer containing a block structural unit (I) mainly composed of polyester units (a1) and a block structural unit (II) mainly composed of polylactic acid units (a2), The composition according to any one of [1] to [6] above, wherein the polyester unit (a1) contains units derived from the aliphatic diol (a1-1) and the aliphatic dicarboxylic acid (a1-2). [8] The composition according to any one of [1] to [7] above, wherein the glass transition temperature of the aliphatic polyester (A) is -40°C or lower. [9] The composition according to any one of [1] to [8] above, wherein the number average molecular weight of the aliphatic polyester (A) is 2,000 to 200,000.

[10] The composition according to any one of [1] to [9] above, wherein the main chain of the aliphatic diol (a1-1) has 4 or more carbon atoms.

[11] The composition according to any one of [1] to

[10] above, wherein the main chain of the aliphatic dicarboxylic acid (a1-2) has 4 to 12 carbon atoms.

[12] The composition according to any one of [1] to

[11] above, wherein the melting point of the aliphatic polyester (A) is 110°C or higher and less than 180°C.

[13] The composition according to [7] above, wherein the amount of block structure unit (II) is 5% by mass or more and 95% by mass or less, relative to 100% by mass of the total of block structure unit (I) and block structure unit (II).

[14] The composition according to any one of [1] to

[13] above, wherein the crosslinking agent (C) is a titanium compound.

[15] An emulsion containing the composition described in any of [1] to

[14] above, wherein the aqueous solvent content in the emulsion is 40% by mass or more.

[16] The emulsion described in

[15] above, wherein the average particle size is 1,000 nm or less.

[17] A method for producing an emulsion as described in

[15] above, Step (1): Disperse the aliphatic polyester (A), which has been dissolved in an organic solvent, in an aqueous solution containing the polyvinyl alcohol (B). A method for producing an emulsion, comprising the step (2) of removing the organic solvent.

[18] A molded article containing any of the compositions described in [1] to

[14] above.

[19] A film containing any of the compositions described in [1] to

[14] above. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a composition that exhibits excellent emulsification properties, the emulsion shows excellent fluidity when formed into an emulsion, and the molded product obtained by drying the emulsion exhibits excellent water resistance and excellent shape retention, an emulsion containing the composition, a method for producing the emulsion containing the composition, and a molded product containing the composition. [Modes for carrying out the invention]

[0010] The following description will be based on an example of an embodiment of the present invention. However, the embodiments shown below are illustrative examples for embodying the technical concept of the present invention, and the present invention is not limited to the following description. In this specification, preferred forms of embodiments are shown, but combinations of two or more individual preferred forms are also preferred forms. If there are several numerical ranges for a given item, a preferred form can be created by selectively combining the lower and upper limits of those ranges. Furthermore, when a numerical range is described as "XX~YY", it means "XX or greater and YY or less". In this specification, "~ unit" (where "~" represents a polymer) means "a unit derived from ~". For example, "polylactic acid unit" means "a unit derived from polylactic acid", and "polyester unit" means "a unit derived from polyester". In this specification, the "main chain" means the longest molecular chain in a molecule. Also, the "branched chain" means a molecular chain other than the main chain in a molecule. In this specification, the "main component" in a structural unit means the unit with the highest content ratio (mass %) among the units constituting the structural unit. The "main component" in a structural unit is, for example, 50 mass % or more, in one aspect 70 mass % or more, in one aspect 80 mass % or more, in one aspect 85 mass % or more, in one aspect 90 mass % or more, and in one aspect 100 mass %. In this specification, "solid content" means the components excluding the solvent. The solid content of the resin composition means the components obtained by removing the solvent from the resin composition.

[0011] [Composition] The composition of the present embodiment is a composition containing an aliphatic polyester (A), polyvinyl alcohol (B), and a crosslinking agent (C), wherein the aliphatic polyester (A) contains units derived from an aliphatic diol (a1-1) and an aliphatic dicarboxylic acid (a1-2), and has an acid value of 10 KOHmg / g or less, and the content of units derived from an aromatic dicarboxylic acid in the aliphatic polyester (A) is 20 mass % or less, and the content of the crosslinking agent (C) is 10 to 100 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol (B).

[0012] The composition of the present embodiment is excellent in emulsification ease, and when made into an emulsion, the emulsion exhibits excellent fluidity, and a molded product obtained by drying the emulsion (hereinafter, also simply referred to as "molded product") exhibits excellent water resistance and excellent shape retention. Although the details of the reason are unknown, it is presumed as follows. Aliphatic polyester (A) is a low-crystallinity polymer containing units derived from aliphatic diol (a1-1) and aliphatic dicarboxylic acid (a1-2), with a unit content of aromatic dicarboxylic acid of 20% by mass or less. Such low-crystallinity polymers are readily soluble in organic solvents such as toluene and are easily emulsified. Therefore, compositions containing easily emulsifiable aliphatic polyester (A) are easily emulsified. Furthermore, generally speaking, in compositions containing a crosslinking agent, crosslinking proceeds when a substance with crosslinkable groups and the crosslinking agent are in close proximity. Similarly, when formed into an emulsion, crosslinking proceeds, and the fluidity of the emulsion decreases. However, it is presumed that the composition of this embodiment exhibits excellent fluidity because, due to the end-group effect resulting from the inclusion of polyvinyl alcohol (B) and crosslinking agent (C) in a specific ratio and the low acid value of the aliphatic polyester (A) (10KOH mg / g or less), the state of existence between the polyvinyl alcohol (B), crosslinking agent (C), and aliphatic polyester (A) in the emulsion is controlled, thereby controlling the crosslinking reaction. In addition, it is presumed that the low crystallinity of the aliphatic polyester (A) and its high molecular mobility also contribute to the control of the above-mentioned state of existence, and is one of the reasons for its excellent fluidity. Furthermore, it is presumed that the above-mentioned state changes in the molded product obtained by drying the emulsion, and the cross-linking reaction proceeds, resulting in excellent water resistance. Additionally, the hydrophilic and hydrophobic properties between the aliphatic polyester (A) and polyvinyl alcohol (B) are involved in forming an appropriate sea-island structure in the molded product, which is one of the reasons for its excellent shape retention. In this specification, "drying" in the context of "molded product obtained by drying emulsion" means applying an emulsion with a solid content of 5-60% by mass to a film thickness of 800 μm after drying, air-drying for 48 hours or more, and then drying in a 100°C hot air dryer for 5 minutes, with a moisture content of 5% by mass or less in that state.

[0013] <Aliphatic polyester (A)> Aliphatic polyester (A) contains units derived from aliphatic diol (a1-1) and aliphatic dicarboxylic acid (a1-2), has an acid value of 10 KOH mg / g or less, and the content of units derived from aromatic dicarboxylic acid in aliphatic polyester (A) is 20% by mass or less.

[0014] The acid value of aliphatic polyester (A) is 10 KOH mg / g or less. An acid value of 10 KOH mg / g or less ensures that the emulsion exhibits excellent fluidity, and the molded product exhibits excellent water resistance and shape retention. From the viewpoint of water resistance and shape retention of the molded product, the acid value of aliphatic polyester (A) is preferably 5 KOH mg / g or less, more preferably 1 KOH mg / g or less. There is no particular limit to the lower limit; it may be greater than 0 KOH mg / g, 0.1 KOH mg / g or more, or 0.5 KOH mg / g or more.

[0015] The content of units derived from aromatic dicarboxylic acids (aromatic carboxylic acid units) in aliphatic polyester (A) is 20% by mass or less. By limiting the aromatic dicarboxylic acid unit content to 20% by mass or less, crystallization of aliphatic polyester (A) is suppressed, resulting in a composition with excellent emulsification properties. Here, the aromatic carboxylic acid unit also includes heteroaromatic carboxylic acid units containing heteroatoms. The aromatic carboxylic acid unit may include either or both heteroaromatic carboxylic acid units containing heteroatoms and heteroaromatic carboxylic acid units not containing heteroatoms, or it may include only one of the two, or it may include only heteroaromatic carboxylic acid units not containing heteroatoms. The content of aromatic dicarboxylic acid units in aliphatic polyester (A) is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and even more preferably 1% by mass or less, and may be 0% by mass, from the viewpoint of better emulsification ease and biodegradability. That is, the content of units derived from aromatic dicarboxylic acid in aliphatic polyester (A) is preferably 0 to 20% by mass, more preferably 0 to 15% by mass, even more preferably 0 to 10% by mass, even more preferably 0 to 5% by mass, and even more preferably 0 to 1% by mass.

[0016] ≪Aliphatic diol (a1-1)≫ Aliphatic polyester (A) contains aliphatic diol (a1-1). The number of carbon atoms in the main chain of the aliphatic diol (a1-1) is preferably 3 or more, more preferably 4 or more, from the viewpoint of the emulsion exhibiting better fluidity and the molded product exhibiting better water resistance and shape retention, and preferably 8 or less, and even more preferably 7 or less, from the viewpoint of exhibiting better biodegradability. In other words, the number of carbon atoms in the aliphatic diol (a1-1) is preferably 3 to 8, more preferably 4 to 7.

[0017] Aliphatic diol (a1-1) is preferably a branched diol, and more preferably a diol having an alkyl group as the branched chain, from the viewpoint of suppressing the crystallization of aliphatic polyester (A), exhibiting excellent biodegradability and ease of emulsification, from the viewpoint of the emulsion exhibiting better fluidity, and from the viewpoint of the molded product exhibiting better flexibility, water resistance, and shape retention. Here, the "branched chain" in aliphatic diol (a1-1) refers to a substructure that branches off from the "main chain" of aliphatic diol (a1-1), and no hydroxyl group is bonded to its end. When an aliphatic diol (a1-1) has a branched chain with an alkyl group, the aliphatic polyester (A) is more likely to become an amorphous polymer. It is presumed that amorphous polymers are more easily penetrated by microorganisms into the polymer structure, resulting in superior biodegradability. However, being an amorphous polymer is only one factor influencing biodegradability. This is because biodegradation is thought to occur through a combination of various factors, such as whether microorganisms recognize the amorphous structure as food, the ease with which enzymes and microorganisms can approach it, steric hindrance of the main chain, melting point, and crystallinity. Therefore, being an amorphous polymer does not automatically mean superior biodegradability.

[0018] In aliphatic diol (a1-1), the number of branched chains is preferably one or two, more preferably one. The branched chains are preferably a methyl group, an ethyl group, and a propyl group, more preferably a methyl group and an ethyl group, and even more preferably a methyl group. Furthermore, if aliphatic diol (a1-1) has multiple branched chains, each branched chain may be the same or different.

[0019] From the viewpoint of readily reacting with dicarboxylic acids, exhibiting superior biodegradability, and exhibiting superior water resistance and shape retention of the molded product, it is preferable that the aliphatic diol (a1-1) has hydroxyl groups at both ends of the main chain. Furthermore, from the viewpoint of readily reacting with dicarboxylic acids and exhibiting superior biodegradability, it is preferable that the two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups. Furthermore, it is preferable that the aliphatic diol (a1-1) does not have a quaternary carbon, from the viewpoint of readily reacting with dicarboxylic acids, exhibiting superior emulsification properties, and exhibiting superior biodegradability.

[0020] Aliphatic diols (a1-1) include, for example, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 1,4-pentanediol, 2-methyl- Examples include 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 2-ethyl-1,6-hexanediol, and 2-methyl-1,8-octanediol. The aliphatic diol (a1-1) is preferably 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2,4-diethyl-1,5-pentanediol, and more preferably 3-methyl-1,5-pentanediol. Aliphatic diols (a1-1) may be used individually or in combination of two or more types.

[0021] From the viewpoint of exhibiting superior emulsification ease and biodegradability, from the viewpoint of the emulsion exhibiting superior fluidity, and from the viewpoint of the molded product exhibiting superior water resistance, shape retention, and hydrolysis resistance, the content of units derived from aliphatic diol (a1-1) in aliphatic polyester (A) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass, relative to the total diol units.

[0022] ≪Aliphatic dicarboxylic acids (a1-2)≫ The number of carbon atoms in the main chain of the aliphatic dicarboxylic acid (a1-2) is preferably 4 to 12. When the aliphatic dicarboxylic acid (a1-2) has 4 or more carbon atoms, the molded product exhibits superior hydrolysis resistance, water resistance, and shape retention. Furthermore, when the aliphatic dicarboxylic acid (a1-2) has 12 or fewer carbon atoms, the biodegradability of the aliphatic polyester (A) is improved. From these perspectives, the number of carbon atoms in the aliphatic dicarboxylic acid (a1-2) is preferably 4 to 10, more preferably 4 to 8, even more preferably 4 to 7, and even more preferably 6 to 7.

[0023] Examples of aliphatic dicarboxylic acids (a1-2) include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanediic acid, and decanedicarboxylic acid. The aliphatic dicarboxylic acids (a1-2) are preferably succinic acid and adipic acid, and more preferably adipic acid. Aliphatic dicarboxylic acids (a1-2) may be used individually or in combination of two or more types.

[0024] From the viewpoint of exhibiting superior emulsification ease and biodegradability, from the viewpoint of the emulsion exhibiting superior fluidity, and from the viewpoint of the molded product exhibiting superior water resistance and shape retention, the content of units derived from aliphatic dicarboxylic acids (a1-2) in aliphatic polyester (A) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass, relative to the total dicarboxylic acid units.

[0025] From the viewpoint of exhibiting superior emulsification and biodegradability, superior fluidity when used as an emulsion, and superior hydrolysis resistance, flexibility, water resistance, and shape retention of the molded product, the preferred combination of aliphatic diol (a1-1) and aliphatic dicarboxylic acid (a1-2) is 3-methyl-1,5-pentanediol and adipic acid.

[0026] The molar ratio of the charges when reacting an aliphatic diol (a1-1) with an aliphatic dicarboxylic acid (a1-2) is preferably 1.4 / 1 to 1 / 1.4, and more preferably 1.2 / 1 to 1 / 1.2.

[0027] Block copolymer From the viewpoint of exhibiting superior emulsification ease, from the viewpoint of the emulsion exhibiting superior fluidity, and from the viewpoint of the molded product exhibiting superior hydrolysis resistance, strength, blocking resistance, water resistance, and shape retention, it is preferable that the aliphatic polyester (A) is a block copolymer containing block structural units (I) mainly composed of polyester units (a1) and block structural units (II) mainly composed of polylactic acid units (a2), and that the polyester units (a1) contain units derived from the aliphatic diol (a1-1) and aliphatic dicarboxylic acid (a1-2).

[0028] <Block structure unit (I)> The block structure unit (I) mainly contains polyester units (a1), and the polyester units (a1) contain units derived from aliphatic diols (a1-1) and aliphatic dicarboxylic acids (a1-2). The content of polyester units (a1) in block structural units (I) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass.

[0029] (Polyester unit (a1)) The polyester unit (a1) contains units derived from an aliphatic diol (a1-1) and an aliphatic dicarboxylic acid (a1-2). Specifically, the polyester unit (a1) contains units derived from a polyester obtained by reacting an aliphatic diol (a1-1) and an aliphatic dicarboxylic acid (a1-2). The polyester unit (a1) may or may not contain units derived from monomers other than the aliphatic diol (a1-1) and the aliphatic dicarboxylic acid (a1-2). That is, the polyester unit (a1) may consist of units derived from an aliphatic diol (a1-1) and an aliphatic dicarboxylic acid (a1-2). Other monomers besides aliphatic diols (a1-1) and aliphatic dicarboxylic acids (a1-2) are not particularly limited as long as they do not impair the effects of the present invention. The total amount of units derived from aliphatic diols (a1-1) and aliphatic dicarboxylic acids (a1-2) in the polyester unit (a1) is preferably 90 mol% or more, more preferably 95 mol% or more, even more preferably 99 mol% or more, and may be 100 mol%. The total amount of units derived from aliphatic diols (a1-1) and aliphatic dicarboxylic acids (a1-2) in the polyester unit (a1) is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more, and may be 100% by mass.

[0030] (Units other than polyester units (a1) (a1')) The block structure unit (I) may or may not contain units other than the polyester unit (a1) (a1'). That is, the block structure unit (I) may contain units other than the polyester unit (a1) (a1'), or it may consist of polyester units (a1). The monomers constituting unit (a1') are not particularly limited as long as they do not impair the effects of the present invention. The content of unit (a1') in block structure unit (I) is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0031] (Number-average molecular weight of block structural units (I)) The number-average molecular weight of the block structural unit (I) is preferably 2,500 or more, more preferably 4,000 or more, even more preferably 5,000 or more, and even more preferably 6,000 or more. Furthermore, the number-average molecular weight of the block structural unit (I) is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 40,000 or less, even more preferably 36,000 or less, and even more preferably 25,000 or less, and may also be 20,000 or less, or 15,000 or less. The number-average molecular weight of the block structural unit (I) is preferably 2,500 to 100,000, more preferably 4,000 to 50,000, even more preferably 5,000 to 40,000, even more preferably 5,000 to 36,000, even more preferably 5,000 to 25,000, even more preferably 5,000 to 20,000, even more preferably 5,000 to 15,000, and even more preferably 6,000 to 15,000. Within the aforementioned numerical range, aliphatic polyester (A) tends to exhibit superior flexibility, impact resistance, productivity, ease of emulsification, and biodegradability. The number-average molecular weight of block structural units (I) can be determined from the number-average molecular weight of aliphatic polyester (A) and the mass content of block structural units (I).

[0032] <Block structure unit (II)> The block structure unit (II) mainly contains polylactic acid units (a2). The inclusion of polylactic acid units (a2) makes it easy to adjust the melting point to above room temperature, improving the handling properties, strength, and heat resistance of the aliphatic polyester (A), and improving the hydrolysis resistance, water resistance, shape retention, and blocking resistance of the molded product. The content of polylactic acid units (a2) in the block structure unit (II) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass.

[0033] (Polylactic acid unit (a2)) The polylactic acid constituting the polylactic acid unit (a2) may be prepared by direct condensation of lactic acid or by ring-opening polymerization of lactide. As the lactic acid, for example, at least one selected from the group consisting of L-lactic acid, D-lactic acid, and DL-lactic acid can be used. As the lactide, for example, at least one selected from the group consisting of L-lactide, D-lactide, DL-lactide, and meso-lactide can be used. Furthermore, polylactic acid can be poly-L-lactic acid, poly-D-lactic acid, poly-DL-lactic acid, or stereocomplex polylactic acid obtained by mixing poly-L-lactic acid and poly-D-lactic acid. From the viewpoint of cost, availability of raw materials, and handling of aliphatic polyester (A), poly-L-lactic acid, poly-D-lactic acid, and poly-DL-lactic acid are preferred. On the other hand, from the viewpoint of synthesis cost and complexity, it is preferable that the polylactic acid is not a stereocomplex polylactic acid. From the viewpoint of exhibiting superior heat resistance and strength, the block structure unit (II) preferably contains 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, units derived from poly-L-lactic acid or poly-D-lactic acid. From the viewpoint of exhibiting superior biodegradability, handling, productivity, and ease of emulsification, the block structural unit (II) preferably contains 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, units derived from polyDL-lactic acid, which is a copolymer of L-lactic acid and D-lactic acid. Furthermore, from the viewpoint of exhibiting superior biodegradability, handling, productivity, ease of emulsification, and ease of raw material availability, as well as from the viewpoint of cost, the block structural unit (II) preferably contains 70-95% by mass, more preferably 80-95% by mass, and even more preferably 90-95% by mass of L-lactic acid, and D-lactic acid preferably contains 5-30% by mass, more preferably 5-20% by mass, and even more preferably 5-10% by mass, based on the total mass of L-lactic acid and D-lactic acid.

[0034] (Units other than polylactic acid units (a2) (a2')) The block structure unit (II) may or may not contain units other than the polylactic acid unit (a2), such as (a2'). The monomers constituting the unit (a2') are not particularly limited as long as they do not impair the effects of the present invention. The content of unit (a2') in block structural unit (II) is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0035] (Number-average molecular weight of block structural units (II)) The number-average molecular weight of block structural units (II) is preferably 1,000 to 100,000, more preferably 1,000 to 25,000, even more preferably 1,000 to 10,000, even more preferably 1,000 to 6,000, and even more preferably 2,000 to 6,000. Within the above numerical range, the emulsion tends to have excellent emulsification and productivity properties, and a viscosity range that is easy to handle as an emulsion. Furthermore, if an aliphatic polyester (A) has multiple block structural units (II), the number-average molecular weight of the block structural units (II) refers to the sum of all block structural units (II). The number-average molecular weight of block structural unit (II) can be determined from the number-average molecular weight of aliphatic polyester (A) and the mass content of block structural unit (II).

[0036] <Ratio of structural units (mass ratio) of block structural units (I) and block structural units (II)> With respect to a total of 100% by mass of block structural units (I) and block structural units (II), block structural unit (II) is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, and even more preferably 35% by mass or more. Furthermore, with respect to a total of 100% by mass of block structural units (I) and block structural units (II), the amount of block structural unit (II) is preferably 95% by mass or less, more preferably 85% by mass or less, even more preferably 75% by mass or less, and even more preferably 60% by mass or less. In other words, with respect to a total of 100% by mass of block structural units (I) and block structural units (II), block structural unit (II) is preferably 5 to 95% by mass, more preferably 15 to 85% by mass, even more preferably 25 to 75% by mass, and even more preferably 35 to 60% by mass. If the proportion of the above block structure unit (II) is 5% by mass or more, the aliphatic polyester (A) tends to have better emulsification properties, handling properties, and strength, and the molded product tends to have better water resistance and shape retention. Furthermore, if the proportion of the above block structure unit (II) is 95% by mass or less, the aliphatic polyester (A) tends to have better flexibility and biodegradability. From the viewpoint of exhibiting superior emulsification ease, handling properties, and strength, and from the viewpoint of the molded product exhibiting superior water resistance and shape retention, the proportion of the block structure unit (II) is more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, from the viewpoint of exhibiting superior flexibility and biodegradability, the proportion of the block structure unit (II) is more preferably 80% by mass or less, even more preferably 75% by mass or less, even more preferably 70% by mass or less, and even more preferably 60% by mass or less. The mass ratio of block structural unit (I) and block structural unit (II) is: 1 It can be determined by 1H-NMR, and specifically by the method described in the examples.

[0037] <Bonding patterns of block copolymers> The bonding form of the block copolymer is preferably triblock or diblock, with the triblock form being more preferred from the viewpoint of blocking resistance. The block copolymer may also be a mixture of triblock and diblock forms. Specifically, the bonding form is preferably [block structural unit (II)]-[block structural unit (I)]-[block structural unit (II)].

[0038] ≪Number average molecular weight of aliphatic polyester (A)≫ The number average molecular weight of the aliphatic polyester (A) is preferably 2,000 or more, more preferably 5,000 or more, even more preferably 8,000 or more, and even more preferably 10,000 or more, from the viewpoint of the molded product exhibiting better water resistance, shape retention, and hydrolysis resistance. From the viewpoint of ease of emulsification, handling, and productivity, the number average molecular weight of the aliphatic polyester (A) is preferably 200,000 or less, more preferably 100,000 or less, even more preferably 50,000 or less, even more preferably 40,000 or less, and even more preferably 30,000 or less. In other words, the number average molecular weight of the aliphatic polyester (A) is preferably 2,000 to 200,000, more preferably 5,000 to 100,000, even more preferably 8,000 to 50,000, even more preferably 10,000 to 40,000, and even more preferably 10,000 to 30,000. The number-average molecular weight of aliphatic polyester (A) can be determined by gel permeation chromatography (GPC), specifically by the method described in the examples.

[0039] ≪Glass transition temperature of aliphatic polyester (A)≫ The glass transition temperature of aliphatic polyester (A) is preferably -40°C or lower. Within this numerical range, aliphatic polyester (A) tends to have excellent flexibility, impact resistance, flex resistance, ease of emulsification, and handling properties. From the viewpoint of exhibiting superior flexibility, impact resistance, and ease of emulsification, the glass transition temperature of the aliphatic polyester (A) is more preferably -45°C or lower, and even more preferably -50°C or lower. A lower limit for the glass transition temperature of the aliphatic polyester (A) is preferable, but for example, it may be -80°C or higher, -70°C or higher, -65°C or higher, or -60°C or higher. From these viewpoints, the glass transition temperature of the aliphatic polyester (A) is preferably -80°C to -40°C, more preferably -70°C to -45°C, -65°C to -50°C, and even more preferably -60°C to -50°C. The glass transition temperature of aliphatic polyester (A) is a value obtained by measurement in accordance with JIS K7121:2012 and can be determined by differential scanning calorimeter.

[0040] ≪Melting point of aliphatic polyester (A)≫ The melting point of the aliphatic polyester (A) is preferably 110°C or higher and less than 180°C. If the melting point of the aliphatic polyester (A) is 110°C or higher, it will have excellent heat resistance, and if it is less than 180°C, it will have superior handling properties, melt moldability, and ease of emulsification. From these viewpoints, the melting point of the aliphatic polyester (A) is preferably 100 to 175°C, more preferably 100 to 150°C, even more preferably 100 to 140°C, and even more preferably 110°C or higher and less than 130°C. The melting point of aliphatic polyester (A) is a value obtained by measurement in accordance with JIS K7121:2012 and can be determined by differential scanning calorimeter.

[0041] [Method for manufacturing aliphatic polyester (A)] A known manufacturing method can be used to produce the aliphatic polyester (A). A method for producing aliphatic polyester (A) may be, for example, a method of reacting an aliphatic diol (a1-1) and an aliphatic dicarboxylic acid (a1-2) using an esterification catalyst (e.g., tin octylate, tin chloride, tin oxide). Furthermore, if the aliphatic polyester (A) is a block copolymer containing a block structural unit (I) mainly composed of polyester units (a1) and a block structural unit (II) mainly composed of polylactic acid units (a2), for example, the polyester constituting the polyester unit (a1) may be synthesized and the polyester may be polymerized with lactide, or a mixture of aliphatic diol (a1-1), aliphatic dicarboxylic acid (a1-2), and lactide may be reacted using an esterification catalyst (for example, tin octoate, tin chloride, tin oxide). The method for producing the polyester may, for example, be a method in which aliphatic diol (a1-1) and aliphatic dicarboxylic acid (a1-2) are reacted using an esterification catalyst (for example, tin octoate, tin chloride, tin oxide). When polymerizing polyester and lactide, it is preferable to use a ring-opening polymerization catalyst (e.g., tin octylate, tin chloride, tin oxide). Polymerization reactions can include solution polymerization, melt polymerization, and interfacial polycondensation, and known polymerization reaction conditions can be set for all of these.

[0042] Furthermore, the method for producing the block copolymer may be, for example, a method in which a polyester constituting the polyester unit (a1) and a polylactic acid constituting the polylactic acid unit (a2) are synthesized separately, and the polyester and the polylactic acid are reacted. Polylactic acid can be synthesized by known methods. For example, polylactic acid may be synthesized by directly reacting lactic acid by a condensation method, or by reacting lactide by a ring-opening polymerization method. When polymerizing polyester and polylactic acid, it is preferable to use an esterification catalyst (e.g., tin octylate, tin chloride, tin oxide). Polymerization reactions can include solution polymerization, melt polymerization, and interfacial polycondensation, and known polymerization reaction conditions can be set for all of these.

[0043] <Polyvinyl alcohol (B)> The vinyl alcohol polymer (B) may be unmodified polyvinyl alcohol, or modified polyvinyl alcohol synthesized by copolymerization, post-modification, etc., to the extent that it does not impair the spirit of the present invention. Components used for copolymerization and post-modification include, for example, α-olefins such as ethylene, propylene, n-butene, and isobutylene; acrylic acid and its salts; acrylamide; acrylamide derivatives such as N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts or its quaternary salts, N-methylolacrylamide and its derivatives; methacrylamide; methacrylamide derivatives such as N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts or its quaternary salts, N-methylolmethacrylamide and its derivatives; methylvinyl Examples include vinyl ethers such as ru ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, and 2,3-diacetoxy-1-vinyloxypropane; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidenes such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid, and their salts or esters; vinylsilyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate. The content of these modifying groups is preferably 0.1 mol% to 10 mol%, more preferably 0.1 mol% to 8.0 mol%, and even more preferably 0.1 mol% to 5.0 mol%. Polyvinyl alcohol (B) may be used alone or in combination of two or more types.

[0044] The viscosity-average degree of polymerization of polyvinyl alcohol (B) is preferably 200 or more, more preferably 500 or more, and even more preferably 1000 or more, from the viewpoint of exhibiting superior emulsification ease, superior dispersion stability of the emulsion when formed into an emulsion, and superior water resistance and shape retention of the molded product. From the viewpoint of exhibiting superior fluidity of the emulsion when formed into an emulsion, and superior water resistance and shape retention of the molded product, it is preferably 5000 or less, more preferably 4000 or less, and even more preferably 3000 or less. The viscosity-average degree of polymerization of polyvinyl alcohol (B) is a value obtained by measurement in accordance with JIS K 6726:1994.

[0045] The degree of saponification of polyvinyl alcohol (B) is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and even more preferably 85 mol% or more, from the viewpoint of exhibiting superior emulsification ease and dispersion stability of the emulsion, and from the viewpoint of exhibiting superior water resistance and shape retention of the molded product. From the viewpoint of exhibiting superior emulsification ease, from the viewpoint of exhibiting superior fluidity of the emulsion when formed into an emulsion, and from the viewpoint of exhibiting superior water resistance and shape retention of the molded product, it is preferably 100 mol% or less, more preferably 98 mol% or less, even more preferably 95 mol% or less, and even more preferably 90 mol% or less. In other words, the degree of saponification of polyvinyl alcohol (B) is preferably 60 to 100 mol%, more preferably 70 to 98 mol%, even more preferably 80 to 95 mol%, and even more preferably 85 to 90 mol%.

[0046] <Crosslinking agent (C)> The crosslinking agent (C) is not particularly limited as long as it reacts with hydroxyl groups to form a crosslinked structure. Examples of crosslinking agents (C) include titanium compounds, zirconium compounds, vanadium compounds, zinc compounds, chromium compounds, nickel compounds, palladium compounds, and boric acid compounds. Among these, titanium-based compounds and zirconium-based compounds are preferably used.

[0047] Examples of titanium-based compounds include titanium lactate, dihydroxytitanium bis(lactate), dihydroxytitanium bis(glycolate)dihydroxybis(lactate), titanium lactate ammonium salt, titanium diammonium, dihydroxybis(slate)titanium ammonium, diisopropoxytitanium bis(triethanolamine), di-n-butoxytitanium bis(triethanolamine), diisopropoxytitanium bis(triethanolamine), and titanium tetrakiss(acetylacetonate). Specific examples of zirconium-based compounds include monohydroxytris(lactate)zirconiumammonium, tetrakis(lactate)zirconiumammonium, and monohydroxytris(slate)zirconiumammonium. Among these, titanium-based compounds are preferred, and titanium lactate and titanium lactate ammonium salts are more preferred. The crosslinking agent (C) may be used alone or in combination of two or more types.

[0048] <Other components in the composition> The composition may also contain other components besides the aliphatic polyester (A), polyvinyl alcohol (B), and crosslinking agent (C). Other components include, for example, water, organic solvents, polymers other than aliphatic polyester (A) and polyvinyl alcohol (B), colorants (pigments or dyes), defoamers, antioxidants, and UV absorbers. Other components in the composition may be added within limits that do not interfere with the effects of the present invention.

[0049] <Content of each component in the composition> The crosslinking agent (C) content in the composition is 10 to 100 parts by mass per 100 parts by mass of polyvinyl alcohol (B). Within the above numerical range, the composition exhibits excellent emulsification properties, the emulsion shows excellent fluidity, and the molded product exhibits excellent water resistance and excellent shape retention. The content of the crosslinking agent (C) in the composition is preferably 10 parts by mass or more, more preferably 13 parts by mass or more, even more preferably 18 parts by mass or more, and even more preferably 23 parts by mass or more, per 100 parts by mass of polyvinyl alcohol (B), from the viewpoint of the molded product exhibiting better water resistance and shape retention, and preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 28 parts by mass or less, from the viewpoint of the emulsion exhibiting better fluidity when formed into an emulsion. In other words, the content of the crosslinking agent (C) in the composition is preferably 10 to 100 parts by mass, more preferably 13 to 50 parts by mass, even more preferably 13 to 28 parts by mass, and even more preferably 18 to 23 parts by mass, per 100 parts by mass of polyvinyl alcohol (B).

[0050] The content of polyvinyl alcohol (B) in the composition is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of aliphatic polyester (A), from the viewpoint of exhibiting better emulsification ease and better fluidity of the emulsion when formed into an emulsion, and preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, from the viewpoint of exhibiting better water resistance and shape retention of the molded product. In other words, the content of polyvinyl alcohol (B) is preferably 1 to 50 parts by mass, more preferably 2 to 40 parts by mass, and even more preferably 3 to 30 parts by mass, per 100 parts by mass of aliphatic polyester (A).

[0051] The total content of aliphatic polyester (A), polyvinyl alcohol (B), and crosslinking agent (C) in the composition is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and may be 100% by mass, from the viewpoint of efficiently obtaining the effects of the present invention.

[0052] [Emulsion] The emulsion of this embodiment is an emulsion containing the above composition, wherein the aqueous solvent content in the emulsion is 40% by mass or more. By having an aqueous solvent content of 40% by mass or more in the emulsion, excellent dispersion stability, shape retention, and handling properties are obtained. The aqueous solvent content in the emulsion is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, from the viewpoint of obtaining better dispersion stability, shape retention, and handling properties, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, from the viewpoint of cost and efficiently obtaining the effects of the present invention. That is, the aqueous solvent content in the emulsion is preferably 40 to 95% by mass, more preferably 50 to 90% by mass, even more preferably 55 to 85% by mass, and even more preferably 60 to 85% by mass.

[0053] The aqueous solvent is preferably mainly composed of water. The aqueous solvent mainly composed of water may also contain water-soluble organic solvents (alcohols, ketones, etc.) that are soluble in water in any proportion. Here, "aqueous medium mainly composed of water" refers to a dispersion medium containing 50% by mass or more of water. From the standpoint of cost and environmental impact, the aqueous solvent preferably contains 90% or more water by mass, and more preferably water.

[0054] The composition content in the emulsion is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of cost, ease of drying, and increasing the amount of active ingredients, and preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of obtaining better dispersion stability and handling properties. In other words, the composition content in the emulsion is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, even more preferably 15 to 45% by mass, and even more preferably 15 to 40% by mass.

[0055] The solid content of the emulsion is preferably 5-60% by mass, more preferably 10-50% by mass, even more preferably 15-45% by mass, and even more preferably 15-40% by mass, from the viewpoint of cost, better dispersion stability, and handling. The solid content in the emulsion refers to the value measured from the residue after heating and drying at 140°C until there is no further change in weight, using a heat-drying type moisture meter.

[0056] From the viewpoint of obtaining better dispersion stability, the particle size of the emulsion is preferably 5,000 nm or less, more preferably 1,000 nm or less, and even more preferably 800 nm or less. From the viewpoint of obtaining better fluidity and handling properties, it is preferably 100 nm or more, even more preferably 200 nm or more, and particularly preferably 300 nm or more. In this specification, "particle size" refers to the median diameter (D_50) measured by a dynamic light scattering measuring device.

[0057] The viscosity of the emulsion is preferably such that it balances handling ease and dispersion stability. 1 The pressure range is 0 to 1,000 mPa·s, more preferably 100 to 500 mPa·s, and even more preferably 200 to 300 mPa·s. In this specification, "emulsion viscosity" refers to the viscosity measured at 23°C three hours after preparing an emulsion containing the composition of the present invention using an E-type viscometer, as described later.

[0058] [Method for manufacturing emulsion] A known manufacturing method can be used to produce the emulsion. From the viewpoint of ease of emulsification, ease of production, and cost, it is preferable to have a step (1) of dispersing the aliphatic polyester (A) dissolved in an organic solvent in an aqueous solution containing the polyvinyl alcohol (B), and a step (2) of removing the organic solvent.

[0059] <Process (1)> Step (1) is a step of dispersing an aliphatic polyester (A) dissolved in an organic solvent in an aqueous solution containing polyvinyl alcohol (B). The organic solvent is not particularly limited as long as it can dissolve the aliphatic polyester (A), but examples include toluene, ethyl acetate, methyl ethyl ketone, and tetrahydrofuran. Among these, toluene is preferred from the viewpoint of efficiently obtaining the effects of the present invention.

[0060] When dissolving aliphatic polyester (A) in an organic solvent, from the viewpoint of ease of emulsification, it is preferable to dissolve it in the organic solvent such that the content of aliphatic polyester (A) is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. Furthermore, from the viewpoint of environmental impact, cost, and completion of step (2) in a short time, it is preferable to dissolve it in the organic solvent such that the content is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. In other words, when dissolving aliphatic polyester (A) in an organic solvent, it is preferable to dissolve it in the organic solvent such that the content of aliphatic polyester (A) is preferably 10 to 70% by mass, more preferably 20 to 50% by mass, and even more preferably 30 to 40% by mass.

[0061] From the viewpoint of exhibiting superior emulsification ease, superior fluidity when formed into an emulsion, and superior water resistance and shape retention of the molded product, it is preferable that the aqueous solution containing polyvinyl alcohol (B) contains polyvinyl alcohol (B) such that the mass ratio of aliphatic polyester (A) to polyvinyl alcohol (B) in the emulsion [(A) / (B)] is preferably 99:1 to 50:50, more preferably 98:2 to 60:40, and even more preferably 97:3 to 70:30. Furthermore, the aqueous solution containing polyvinyl alcohol (B) may or may not contain a water-soluble organic solvent.

[0062] A known method can be used to disperse an aliphatic polyester (A) dissolved in an organic solvent in an aqueous solution containing polyvinyl alcohol (B). When dispersing, a dispersion device such as a high-pressure homogenizer may be used in conjunction if necessary.

[0063] <Process (2)> Step (2) is the step of removing the organic solvent. From a productivity standpoint, it is preferable to remove the organic solvent by heating the solution obtained in step (1). The temperature at which the solution obtained in step (1) is heated is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher, from the viewpoint of productivity and suppression of the decomposition of aliphatic polyester (A). From the viewpoint of productivity and suppression of the decomposition of aliphatic polyester (A), it is preferably 120°C or lower, more preferably 110°C or lower, and even more preferably 105°C or lower. That is, the temperature at which the solution obtained in step (1) is heated is preferably 70 to 120°C, more preferably 80 to 110°C, and even more preferably 90 to 105°C.

[0064] The crosslinking agent (C) may be added in step (1), before step (2), in step (2), or after step (2). Furthermore, the crosslinking agent (C) may be added to the organic solvent used to dissolve the aliphatic polyester (A), to an aqueous solution containing polyvinyl alcohol (B), to the solution obtained in step (1), or to the solution obtained by removing the organic solvent from the solution obtained in step (1). From the viewpoint of handling, it is preferable to add it after step (2), that is, to the solution obtained in step (1) from which the organic solvent has been removed.

[0065] [Molded product] The molded product of this embodiment contains the composition of this embodiment. The shape and manufacturing method of the molded product of this embodiment are not particularly limited, but the emulsion containing the composition of this embodiment may be applied and then dried to form a coating, i.e., a film. The following are some, but are not limited to, the applications of the molded product of this embodiment. Applications of the molded product of this embodiment include, for example, various molded products, packaging materials, sanitary materials, medical materials, clothing materials, agricultural materials, horticultural materials, fishing materials, foamed resin materials, civil engineering and construction materials, automobile parts, electrical and electronic components, and the like. Examples of packaging materials include shrink film, metallized film, plastic wrap, food packaging, clamshell packaging, garbage bags, shopping bags, standard bags, heavy-duty bags, eco-bags, tube containers, container stoppers, blister packaging, food trays, glasses, mugs, paper cups, lids for paper cups, tableware, plates, various containers and bottles, oil containers, and other general packaging. Examples of sanitary materials include disposable diapers and sanitary products. Examples of materials used in clothing include waterproof films, breathable films, hat top buttons, clothing buttons, zippers, footwear such as fashion sandals, and raincoats. Examples of agricultural materials include agricultural mulch film, protective film, seedling pots, mulch film, and labels. Examples of automotive parts include trim parts, mats, coatings, protective layers, transparent automotive parts, tubes, connectors, interior parts, and exterior parts. Examples of electrical and electronic components include components for home appliances, components for multifunction printers, protective films, and piezoelectric elements. In addition, it can be suitably used for cable ties, prepaid cards, balloons, umbrellas, plastic gloves, cushioning materials, insulation materials, packaging materials, hoses, rulers, straws, and more.

[0066] The moisture content of the film in this embodiment is preferably less than 5% by mass, more preferably less than 3% by mass, and even more preferably less than 1% by mass, from the viewpoint of water resistance and shape retention. There is no particular lower limit to the moisture content of the film in this embodiment, but it may be 0.5% by mass or more, 0.1% by mass or more, or less than 0.1% by mass. [Examples]

[0067] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0068] The compounds used in the examples and comparative examples are as follows: • 3-methyl-1,5-pentanediol (manufactured by Kuraray Co., Ltd.) • Adipic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) • Tin octoate (manufactured by Tokyo Chemical Industry Co., Ltd.) • Toluene (manufactured by Kishida Chemical Co., Ltd.) • L-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.) • D-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.) • Methanol (manufactured by Fujifilm Wako Pure Chemical Corporation) • Polyvinyl alcohol 1: "Kuraray Poval (registered trademark) 22-88" (manufactured by Kuraray Co., Ltd.) • Crosslinking agent 1: "Orgatics TC-300" (manufactured by Matsumoto Fine Chemical Co., Ltd.) • Crosslinking agent 2: "Orgatics TC-315" (manufactured by Matsumoto Fine Chemical Co., Ltd.)

[0069] The physical properties of the aliphatic polyester (A), composition, and emulsion in the examples and comparative examples were measured or evaluated by the following methods.

[0070] (1) Number average molecular weight (Mn) The number-average molecular weight (Mn) (also known as polymer Mn) of aliphatic polyester (A) before emulsion production and in the emulsion within 6 hours after emulsion production was determined using gel permeation chromatography (GPC), in terms of standard polystyrene equivalent. <GPC measurement conditions> Equipment: GPC system "HLC-8220" manufactured by Tosoh Corporation Separation column: Tosoh Corporation "TSKgel SuperMultiporeHZ-M (column diameter = 4.6 mm, column length = 15 cm)" (used by connecting two in series) Eluent: Tetrahydrofuran (THF) Eluent flow rate: 0.35mL / min Column temperature: 40℃ Detection method: Differential refractive index (RI) Injection volume: 10μL Concentration: 1 mg / 1 mL (Aliphatic polyester (A) / THF)

[0071] (2) Mass ratio (block structural unit (I):block structural unit (II)) 1 The mass ratio (block structure unit (I):block structure unit (II)) between block structure units (I):block structure unit (II) was calculated using 1H-NMR. In other words, 1The molar ratio of block structural unit (I): block structural unit (II) was calculated from the area ratio of the signal around 0.9 ppm originating from block structural unit (I), which is mainly composed of polyester units (a1), and the signal around 5.2 ppm originating from polylactic acid units, obtained by 1H-NMR. The mass ratio of block structural unit (I): block structural unit (II) was obtained by multiplying this molar ratio by the molecular weight of the block structural unit. < 1 Measurement conditions for H-NMR Equipment: Nuclear magnetic resonance apparatus “JNM-ECX400” manufactured by JEOL Ltd. Solvent: Deuterated chloroform Measurement temperature: 50℃ Total number of times: 1024 Measurement conditions: Heating rate 10°C / min

[0072] (3) Glass transition temperature The glass transition temperature (°C) was measured using a differential scanning calorimeter in accordance with JIS K7121:2012. In this specification, the glass transition temperature is defined as the intermediate glass transition temperature in JIS K7121:2012. Specifically, under the following measurement conditions: nd The glass transition temperature (°C) was measured during the run test. <Measurement conditions for glass transition temperature> Using a differential scanning calorimetry analyzer "DSC822" (manufactured by Mettler Toledo Co., Ltd.), an aliphatic polyester (A) at 25°C was heated to 200°C at a heating rate of 10°C / min (1 st (run), held at 200°C for 5 minutes, then cooled from 200°C to 75°C at a rate of 10°C / min, and held at 75°C for 30 minutes (crystallization). Subsequently, cooled from 75°C to -50°C at a rate of 10°C / min, cooled from -50°C to -75°C at a rate of 5°C / min, and held at -75°C for 5 minutes. Subsequently, heated from -75°C to 250°C at a rate of 10°C / min (2 nd (run).

[0073] (4) Acid value The acid value was measured by indicator titration according to Method A of JIS K 1557-1:2007.

[0074] (5)Easy emulsification A mixture of aliphatic polyester (A), polyvinyl alcohol (B), and a crosslinking agent (C) was prepared by mixing 10 g of a composition in the same proportions as the emulsions or aqueous solutions obtained in the respective examples and comparative examples. This mixture was then mixed with 90 g of toluene to prepare a mixed solution containing 10% by mass of the composition. The mixed solution was placed in a 500 mL flask fitted with a Liebig cone and heated at 100 °C for 1 hour while stirring at 150 rpm, then cooled to 50 °C over 1 hour. Subsequently, the 50 °C mixed solution was passed by gravity through a nylon filter sheet "NRS-425" (manufactured by Nippon Rikagaku Kikai Co., Ltd.) with a mesh size of 425 μm. The mixed solution that passed through the nylon filter sheet was air-dried for 48 hours or more, then dried in a hot air dryer at 120 °C for 2 hours, and the percentage of the mass that passed through (passage rate) was calculated. The emulsification properties of the composition were evaluated from the passage rate according to the evaluation criteria below. A: Pass-through mass ratio is 60% or higher B: Pass-through mass ratio is 10% or more but less than 60% F: Mass transmission rate is less than 10% A higher pass-through mass rate indicates better emulsification properties.

[0075] (6) Solid content concentration Using a heat-drying type moisture meter (manufactured by A&D Co., Ltd.), the emulsions or aqueous solutions obtained in the examples and comparative examples were heated at 140°C until the mass change was 0.05% by mass / minute or less, and the solid content concentration was calculated. Based on the calculated mass retention rate, the solid content concentration was evaluated according to the following evaluation criteria. A: Solid content concentration of 20% by mass or more F: Solid content concentration less than 20% by mass

[0076] (7) Liquidity The emulsions or aqueous solutions obtained in the examples and comparative examples were passed through a nylon filter sheet "NRS-425" (manufactured by Nippon Rikagakukikai Co., Ltd.) with a mesh size of 425 μm by gravity. The mass percentage (passage rate) of the emulsion or aqueous solution that passed through the nylon filter sheet was calculated, and the fluidity of the emulsion and aqueous solution was evaluated from the passage rate according to the evaluation criteria below. A: Passing mass rate is 90 mass% or more F: Pass-through mass rate is less than 90% by mass. If the percentage of the material that passes through (passage rate) is 90% by mass or more, the emulsion can be said to have excellent fluidity and ease of emulsification.

[0077] (8)Water resistance The emulsions or aqueous solutions obtained in the examples and comparative examples were air-dried for 48 hours or more, and then dried in a hot air dryer at 100°C for 5 minutes to produce cast films with dimensions of 1 cm × 4 cm and a thickness of 800 μm. The prepared cast films were immersed in water at 20°C or 40°C for 24 hours, and then filtered by gravity using a nylon filter sheet "NRS-425" (manufactured by Nippon Rikagaku Kikai Co., Ltd.) with a mesh size of 425 μm. The residue was dried in a hot air dryer at 120°C for 2 hours, and the residue rate (by mass) was calculated. Based on the calculated survival rate, the water resistance of the cast film was evaluated according to the following evaluation criteria. A: Remaining percentage of 80% or more by mass B: Remaining percentage is 75% by mass or more and less than 80% by mass. F: Remaining percentage less than 75% by mass A material with a mass retention rate of 80% or more by mass can be said to have excellent water resistance.

[0078] (9) Shape retention Similar to the water resistance evaluation, a cast film measuring 1 cm x 4 cm with a thickness of 800 μm was prepared. The prepared cast films were immersed in 20°C water for 24 hours, and then visually observed to evaluate their shape retention according to the following evaluation criteria. A: No separation or holes have occurred. F: At least one selected from the group consisting of separation and holes occurs.

[0079] [Example 1] (1) Production of aliphatic polyester (A) In a flask equipped with apparatus for distilling off the generated liquid and a vacuum pump, 3-methyl-1,5-pentanediol and adipic acid were charged in a molar ratio of 3-methyl-1,5-pentanediol / adipic acid = 1.1 / 1. Then, tin octylate was added to the total amount of 3-methyl-1,5-pentanediol and adipic acid at 0.1% by mass. The mixture was heated under a nitrogen atmosphere, at atmospheric pressure, at 160°C for 3 hours, and then at 220°C for another 3 hours while distilling off the water. Next, the pressure was reduced to 2,000 Pa and the mixture was reacted for 3 hours, then the pressure was reduced to 80 Pa and the reaction was continued while checking as needed until the number average molecular weight reached 6,000. After the reaction was complete, the pressure was returned to atmospheric pressure, and the temperature was cooled to 80°C. Toluene was added to dilute the mixture to a solid content of 40% by mass, and then the above toluene solution was added to twice the volume (by mass) of methanol. The supernatant was discarded, and the mixture was washed again with methanol in an amount equal to the amount of toluene solution added (by mass). The supernatant was discarded, and the recovered insoluble matter was dried in a vacuum dryer at a temperature of 40°C to remove organic volatiles and obtain the polymer. The obtained polymer was diluted by adding toluene again to the toluene solution of the polymer so that the solid content of the toluene solution was 33% by mass. Then, the temperature was raised to 140°C to remove 10% by mass of the added toluene by distillation, thereby dehydrating the system. Subsequently, the toluene solution of the polymer was cooled to 80°C, and the polymer solids and L-lactide were added in a mass ratio of polymer / L-lactide = 50 / 50. Further, the amount of toluene removed by distillation (by mass) was added to adjust the solid content of the toluene solution of the polymer and L-lactide to 50% by mass. After that, when the temperature of the solution was raised to 100°C, 0.1% by mass of tin octylate was added relative to the polymer, and the mixture was reacted for 4 hours to synthesize aliphatic polyester (A-1), and a toluene solution of the aliphatic polyester (A-1) was obtained. To this solution, toluene was added to dilute it to a solid content of 40% by mass. Then, the toluene solution with a solid content of 40% by mass was added to twice the volume of methanol (by mass) of the total solution to precipitate the solid. The supernatant methanol was discarded, and the same volume of methanol (by mass) as the added toluene solution was added again for washing. The methanol was discarded, and the recovered solid was dried in a vacuum dryer at 40°C to remove organic volatiles and obtain an aliphatic polyester (A-1). The obtained aliphatic polyester (A-1) was subjected to the measurements and evaluations described above. The results are shown in Table 1.

[0080] (2) Preparation of emulsions containing the composition The obtained aliphatic polyester (A-1) was dissolved in toluene to obtain a polymer solution containing 20% ​​by mass of aliphatic polyester (A-1). Subsequently, this polymer solution and an aqueous solution obtained by dissolving polyvinyl alcohol 1 in water were mixed so that the polyvinyl alcohol 1 content was 30 parts by mass per 100 parts by mass of aliphatic polyester (A-1) and the solid content was 10% by mass, to obtain 400 g of the mixture. This mixture was stirred for 5 minutes at a peripheral speed of 17.5 m / s using a precision emulsifying and dispersing machine "Creamix" (manufactured by M-Technique Co., Ltd.) to obtain a dispersion. Next, the dispersion was heated to a temperature of 85°C, and toluene was removed from the dispersion by blowing nitrogen into the gas phase as needed to remove the toluene vapor generated. To the dispersion from which toluene has been removed, crosslinking agent 1 was mixed in an amount of 15 parts by mass per 100 parts by mass of polyvinyl alcohol 1 to obtain emulsion X1 containing a composition comprising aliphatic polyester (A), polyvinyl alcohol (B), and crosslinking agent (C). The obtained emulsion X1 was subjected to the measurements and evaluations described above. The results are shown in Table 1.

[0081] [Examples 2 and 3, and Comparative Examples 1 and 2] Emulsions X2, X3, Y1, and Y2 were obtained in the same manner as in Example 1, except that the crosslinking agent 1 was mixed in the amount shown in Table 1. The obtained emulsions X2, X3, Y1, and Y2 were subjected to the measurements and evaluations described above. The results are shown in Tables 1 and 2.

[0082] [Example 4] Emulsion X4 was obtained in the same manner as in Example 1, except that crosslinking agent 2 was used instead of crosslinking agent 1, and crosslinking agent 2 was mixed in the amount shown in Table 1. The obtained emulsion X4 was subjected to the measurements and evaluations described above. The results are shown in Table 1.

[0083] [Example 5] Aliphatic polyester (A-2) was obtained in the same manner as in Example 1, except that instead of adding the polymer solids and L-lactide in a mass ratio of polymer / L-lactide = 50 / 50, the polymer / L-lactide / D-lactide was added in a mass ratio of polymer / L-lactide / D-lactide = 50 / 45 / 5. Furthermore, emulsion X5 was obtained in the same manner as in Example 1, except that aliphatic polyester (A-2) was used instead of aliphatic polyester (A-1), and crosslinking agent 1 was mixed in the amount shown in Table 1. The obtained emulsion X5 was subjected to the measurements and evaluations described above. The results are shown in Table 1.

[0084] [Comparative Example 3] Water, polyvinyl alcohol 1, and crosslinking agent 1 were mixed to obtain an aqueous solution Y3 in which the polyvinyl alcohol 1 content was 10% by mass and the crosslinking agent 1 content was 15 parts by mass per 100 parts by mass of polyvinyl alcohol 1. The obtained aqueous solution Y3 was subjected to the measurements and evaluations described above. The results are shown in Table 2.

[0085] [Comparative Example 4] Water, polyvinyl alcohol 1, and crosslinking agent 1 were mixed to obtain an aqueous solution Y4 in which the polyvinyl alcohol 1 content was 5.3% by mass and the crosslinking agent 1 content was 15 parts by mass per 100 parts by mass of polyvinyl alcohol 1. The obtained aqueous solution Y4 was subjected to the measurements and evaluations described above. The results are shown in Table 2.

[0086] [Comparative Example 5] Water, polyvinyl alcohol 1, and crosslinking agent 2 were mixed to obtain an aqueous solution Y5 in which the polyvinyl alcohol 1 content was 5.3% by mass and the crosslinking agent 2 content was 100 parts by mass per 100 parts by mass of polyvinyl alcohol 1. The obtained aqueous solution Y5 was subjected to the measurements and evaluations described above. The results are shown in Table 2.

[0087] [Table 1]

[0088] [Table 2]

[0089] The compounds represented by the abbreviations in Tables 1 and 2 are as follows: PLA: Polylactic acid MPD: 3-methyl-1,5-pentanediol AA: Adipic acid

[0090] As shown in the examples, the composition containing an aliphatic polyester (A), polyvinyl alcohol (B), and a crosslinking agent (C) exhibits excellent emulsification properties, and when formed into an emulsion, the emulsion shows excellent fluidity. The molded product obtained by drying the emulsion exhibits excellent water resistance and excellent shape retention. Therefore, the industrial utility of the composition of this embodiment is extremely high.

Claims

1. A composition containing an aliphatic polyester (A), polyvinyl alcohol (B), and a crosslinking agent (C), The aliphatic polyester (A) contains units derived from an aliphatic diol (a1-1) and an aliphatic dicarboxylic acid (a1-2), and has an acid value of 10 KOH mg / g or less. The content of units derived from aromatic dicarboxylic acids in the aliphatic polyester (A) is 20% by mass or less. A composition in which the crosslinking agent (C) is contained in an amount of 10 to 100 parts by mass per 100 parts by mass of polyvinyl alcohol (B).

2. The composition according to claim 1, wherein the content of the polyvinyl alcohol (B) is 1 to 50 parts by mass per 100 parts by mass of the aliphatic polyester (A).

3. The composition according to claim 1 or 2, wherein the aliphatic diol (a1-1) is a diol having a branched chain.

4. The composition according to claim 1 or 2, wherein the aliphatic diol (a1-1) is a diol having a methyl group as a branched chain.

5. The composition according to claim 1 or 2, wherein the two hydroxyl groups of the aliphatic diol (a1-1) are primary hydroxyl groups.

6. The composition according to claim 1 or 2, wherein the aliphatic diol (a1-1) does not have a quaternary carbon.

7. The aliphatic polyester (A) is a block copolymer containing a block structural unit (I) mainly composed of polyester units (a1) and a block structural unit (II) mainly composed of polylactic acid units (a2). The composition according to claim 1 or 2, wherein the polyester unit (a1) contains units derived from the aliphatic diol (a1-1) and the aliphatic dicarboxylic acid (a1-2).

8. The composition according to claim 1 or 2, wherein the glass transition temperature of the aliphatic polyester (A) is -40°C or lower.

9. The composition according to claim 1 or 2, wherein the number average molecular weight of the aliphatic polyester (A) is 2,000 to 200,000.

10. The composition according to claim 1 or 2, wherein the main chain of the aliphatic diol (a1-1) has four or more carbon atoms.

11. The composition according to claim 1 or 2, wherein the main chain of the aliphatic dicarboxylic acid (a1-2) has 4 to 12 carbon atoms.

12. The composition according to claim 1 or 2, wherein the melting point of the aliphatic polyester (A) is 110°C or higher and less than 180°C.

13. The composition according to claim 7, wherein the amount of block structure unit (II) is 5% by mass or more and 95% by mass or less, relative to 100% by mass of the total of block structure unit (I) and block structure unit (II).

14. The composition according to claim 1 or 2, wherein the crosslinking agent (C) is a titanium-based compound.

15. An emulsion containing the composition according to claim 1 or 2, wherein the aqueous solvent content in the emulsion is 40% by mass or more.

16. The emulsion according to claim 15, wherein the average particle size is 1,000 nm or less.

17. A method for producing an emulsion according to claim 15, Step (1): Disperse the aliphatic polyester (A), which has been dissolved in an organic solvent, in an aqueous solution containing polyvinyl alcohol (B). A method for producing an emulsion, comprising the step (2) of removing the organic solvent.

18. A molded article containing the composition described in claim 1 or 2.

19. A film containing the composition according to claim 1 or 2.

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