WO2022071219A1

WO2022071219A1 - Water-based dispersion of graft-modified biodegradable polyester resin

Info

Publication number: WO2022071219A1
Application number: PCT/JP2021/035353
Authority: WO
Inventors: 博俊木津本; 万紀木南
Original assignee: 東洋紡株式会社
Priority date: 2020-09-30
Filing date: 2021-09-27
Publication date: 2022-04-07
Also published as: JPWO2022071219A1

Abstract

[Problem] To provide a water-based dispersion of fine particles that have excellent dispersion stability while maintaining the excellent biodegradability that is inherent to biodegradable polyester resins. [Solution] This water-based dispersion is of an acid-modified polyester resin (B) having a structure obtained through graft addition of an unsaturated polycarboxylate as a side chain to a biodegradable polyester resin (A).

Description

Graft-modified biodegradable polyester resin aqueous dispersion

The present invention relates to an aqueous dispersion of an acid-modified polyester resin having biodegradability suitable for applications such as coating agents, paints, inks and adhesives.

In recent years, there has been increasing interest in materials that have a low environmental impact due to consideration for the environment, and so far, polymer materials that are derived from natural products and have biodegradability, such as polylactic acid and starch, have been proposed. Came. In addition, volatile organic compound (VOC) regulations have become stricter, and in the industry dealing with coating agents and paints, the conventional organic solvent type is shifting to water-based dispersion type and solvent-free type. In terms of versatility, it is highly versatile, and the number of adoption cases is increasing.
Under such circumstances, aqueous dispersions of biodegradable resins have attracted attention in various fields, and various proposals have been made for methods for preparing these dispersions. For example, in Patent Document 1, a dispersion using an anionic surfactant as an emulsifier is used. In Patent Document 3, the dispersion for ensuring stability was thickened and stabilized by coexisting a small amount of polysaccharide in an amine-neutralized aqueous dispersion of a biodegradable resin to which an acid value was added by depolymerization. Each dispersion has been proposed. Further, in Patent Document 4, a biodegradable polyester resin and a hydrophilic polyester resin containing a sulfonic acid base are melt-mixed to prepare an emulsified aqueous dispersion as a mixture, and in Patent Document 5, polyvinyl alcohol is biodegradable. A dispersion of a biodegradable polyester resin used as an emulsifier has been proposed. Further, in Patent Document 6, a relatively low molecular weight biodegradable polyester resin having a hydroxyl group is reacted with a polyvalent carboxylic acid anhydride to introduce an acid value, and a self-emulsifying aqueous dispersion is prepared by amine neutralization. In Tate and Patent Document 7, a dispersion obtained by emulsion-polymerizing a polymerizable unsaturated monomer in the coexistence of a biodegradable resin and encapsulating the biodegradable resin in micelle particles formed from a polymer of the unsaturated monomer. Proposed.

Japanese Patent Application Laid-Open No. 10-101911 Japanese Patent Application Laid-Open No. 11-92712 JP-A-2002-241629 Japanese Patent Application Laid-Open No. 2003-96281 JP-A-2004-204038 JP 2000-7789 JP-A-2005-344013

However, in the cases of Patent Documents 1 to 5, the biodegradable resin aqueous dispersion particles obtained in any case have a large average particle size or a wide particle size distribution and contain coarse particles, so that the dispersion is stable in storage. The sex is not enough. Further, in Patent Document 6, although a dispersion of fine particles is obtained, an aqueous dispersion of fine particles cannot be formed while the biodegradable resin maintains a high molecular weight. Further, in Patent Document 7, although a dispersion having a core / shell structure of relatively fine particles is obtained, many components do not have a biodegradable function constituting the shell, and the biodegradable resin originally forming the core is formed. There was a problem that the biodegradation function of was not fully exhibited.

As a result of diligent studies by the present inventors to solve the above problems, the acid-modified polyester resin having a hydrophilic polar group introduced by graft-adding an unsaturated polyvalent carboxylic acid compound to the biodegradable polyester resin skeleton is biodegraded. We have found that it is possible to form an aqueous dispersion of fine particles having excellent dispersion stability while maintaining the original excellent biodegradability of the polyester resin, and have reached the present invention.

That is, the present invention provides an aqueous dispersion of an acid-modified polyester resin (B) having a structure in which an unsaturated polyvalent carboxylic acid is grafted as a side chain of the biodegradable polyester resin (A).

The acid value of the acid-modified polyester resin (B) is preferably 150 equivalents / ton or more.

The unsaturated polyvalent carboxylic acid is preferably maleic acid, itaconic acid or an anhydrate thereof.

The biodegradable polyester resin (A) is at least one selected from the group consisting of aliphatic dibasic acid and aliphatic dibasic acid, and one or more selected from the group consisting of aliphatic glycol and aliphatic glycol. It is preferable that it is a polyester resin (A1) having the above as a structural unit or a polyester resin (A2) having an aliphatic oxycarboxylic acid as a structural unit.

The polyester resin (A1) has a total amount of aliphatic dibasic acid, alicyclic dibasic acid, aliphatic glycol and alicyclic glycol, which is 50 mol with respect to the total amount of monomers constituting the polyester resin (A1). It is preferable that the polyester (A2) has 40 mol% or more of the aliphatic oxycarboxylic acid with respect to the total amount of monomers constituting the polyester resin (A2).

The aqueous dispersion preferably contains the acid-modified polyester resin (B) and an organic amine compound.

It is preferable that the aqueous dispersion contains substantially no emulsifier.

The aqueous dispersion can be suitably used as a coating agent and an adhesive.

The acid-modified polyester resin having a structure in which an unsaturated polyvalent carboxylic acid is grafted as a side chain of the biodegradable polyester resin of the present invention is mainly composed of an unsaturated polyvalent carboxylic acid grafted to the side chain. It can be stably emulsified and dispersed in the form of fine particles in an aqueous medium without the presence of an emulsifier while leaving the skeleton. In addition, the content of components other than the original biodegradable resin skeleton is small, and the excellent biodegradable function of the biodegradable polyester resin is maintained.

Embodiment of the invention

Hereinafter, embodiments of the present invention will be described.

<Unsaturated polyvalent carboxylic acid>
The unsaturated polyvalent carboxylic acid used in the present invention is not particularly limited as long as it is a compound having at least one unsaturated bond and two or more carboxyl groups in one molecule. There may be two or more unsaturated bonds in one molecule. Examples of unsaturated polyvalent carboxylic acids include maleic acid and its anhydride, itaconic acid and its anhydride, fumaric acid and its anhydride, citraconic acid and its anhydride, mesaconic acid and its anhydride, and 2-pentenylic acid. And its anhydrides, 3-dodecenyl autic acid and its anhydrides, octenyl amber acid and its anhydrides, dimer acid, various unsaturated fatty acids contained in vegetable oils and the like. These can be used alone or in combination of two or more. Maleic acid, itaconic acid and their respective acid anhydrides are preferable from the viewpoint of reactivity and versatility. The graft addition reaction of unsaturated polyvalent carboxylic acid is carried out in a heated state, and some biodegradable resins deteriorate when the carboxylic acid coexists at a high concentration in the heated state. Therefore, maleic anhydride and itaconic anhydride are most preferable.

<Biodegradable polyester resin (A)>
The biodegradable polyester resin (A) used in the present invention is a biodegradable polyester resin and has the property of being decomposed by the action of microorganisms. Examples of the origin of the biodegradable polyester resin include those derived from microorganisms, those derived from natural products, and those derived from chemical synthesis, including polylactic acid, polyhydroxyalkanoic acid, polyglycolic acid, aliphatic polyesters, and aromatic-modified aliphatic polyesters. Etc. are exemplified.
The biodegradable polyester resin (A) used in the present invention is not particularly limited as long as it has biodegradability, and is, for example, a group consisting of an aliphatic dibasic acid and an alicyclic dibasic acid as an acid component. As a structural unit, a polyester resin (A1) having one or more selected from the above and one or more selected from the group consisting of aliphatic glycols and aliphatic glycols as glycol components as structural units, or aliphatic oxycarboxylic acids. Examples thereof include a polyester resin (A2) having a resin.

<Polyester resin (A1)>
Examples of the aliphatic dibasic acid constituting the polyester resin (A1) include linear aliphatic dibasic acids such as amber acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid and dodecandicarboxylic acid. Branched aliphatic dizygous acid such as 2-ethyladipic acid, 3-ethyladipic acid, 2-isopropyladipic acid, 2,5-dimethyladipic acid, 2-methylsveric acid, 3-methylsveric acid, 4-methylsveric acid, etc. Although basic acids can be mentioned, among these, amber acid, adipic acid and sebacic acid are preferable from the viewpoint of versatility, and amber acid and sebacic acid are more preferable from the viewpoint of raw materials for biomass. As the alicyclic dibasic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydrochloride anhydride, 4-methylhexahydrohydride phthalic acid, 4-cyclohexene- Examples thereof include alicyclic dibasic acid raw materials such as 1,2-dicarboxylic acid, and among these, 1,4-cyclohexanedicarboxylic acid is preferable in terms of versatility.

As the aliphatic glycol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-n-butyl-2-ethyl-1,3-propylene glycol, 1,2-butylene glycol, 1, 3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 2-methyl-1,3-propylene glycol, neopentyl glycol, 2,2-dimethyl-3-hydroxypropyl-2', 2' -Didimethyl-3-hydroxypropanol, 2,2-diethyl-1,3-propylene glycol, 1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,2-diethyl-1, 5-Pentanediol, 1,3-diethyl-1,5-pentanediol, 1,4-diethyl-1,5-pentanediol, 2,3-diethyl-1,5-pentanediol, 2-ethyl-4- Isopropyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 3-ethyl-1,5-pentanediol, 3-propyl-1,5-pentanediol, 3-octyl-1,5- Pentandiol, 2,2,4-trimethyl-1,3-pentanediol, 3-octyl-1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 1,7 Examples thereof include aliphatic diols such as -heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol and 1,12-dodecanediol. Of these, from the aspect of versatility, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, neopentyl glycol, 1,6-hexane Diol is preferable, and ethylene glycol and 1,3-propylene glycol are more preferable from the viewpoint of these internal biomass raw materials.

As the alicyclic glycol, 1,3-bis (hydroxymethyl) cyclohexane, 1,4-bis (hydroxymethyl) cyclohexane, 1,4-bis (hydroxyethyl) cyclohexane, 1,4-bis (hydroxypropyl) cyclohexane, 1,4-bis (hydroxymethoxy) cyclohexane, 1,4-bis (hydroxyethoxy) cyclohexane, 2,2-bis (4-hydroxymethoxycyclohexyl) propane, 2,2-bis (4-hydroxyethoxycyclohexyl) propane, Bis (4-hydroxycyclohexyl) methane, 2,2-bis (4-hydroxycyclohexyl) propane, 3 (4), 8 (9) -tricyclo [5.2.1.0 ^2,6 ] decandimethanol, etc. Examples thereof include alicyclic diol raw materials, and among these, 1,4-bis (hydroxymethyl) cyclohexane is preferable in terms of versatility.

The contents of the aliphatic dibasic acid, the alicyclic dibasic acid, the aliphatic glycol and the alicyclic glycol constituting the polyester resin (A1) are aliphatic with respect to the total amount of the monomers constituting the polyester resin (A1). From the viewpoint of biodegradability, the total amount of the dibasic acid, the aliphatic dibasic acid, the aliphatic glycol and the alicyclic glycol is preferably 50 mol% or more. It is more preferably 70 mol% or more, further preferably 80% or more, most preferably 90 mol% or more, and may be 100 mol% or more.

In addition to the aliphatic and alicyclic dibasic acids and aliphatic and alicyclic glycols, the polyester resin (A1) contains an aromatic dibasic acid for the purpose of improving the physical properties of the acid-modified polyester resin (B) of the present invention. Alternatively, the glycol component having an aromatic ring may be copolymerized as long as the biodegradability is not impaired. Examples of the aromatic dibasic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, and aromatic dibasic acids such as anhydrides thereof. From the viewpoint of versatility and polymerization reactivity, terephthalic acid, isophthalic acid, orthophthalic acid, and 2,6-naphthalenedicarboxylic acid are preferable. In addition, examples of the glycol component having an aromatic ring include a polyalkylene oxide adduct to bisphenol A. From the viewpoint of biodegradability, the copolymerization ratio of these aromatic dibasic acids and glycol components having an aromatic ring is preferably less than 50 mol% when the total dibasic acid component and the total glycol component are 100 mol%, respectively. More preferably less than 45 mol%.

In addition to the above acid component and glycol component, the polyester resin (A1) of the present invention is copolymerized with a polyfunctional compound such as trimethylolpropane, trimellitic acid, or trimellitic anhydride as long as the polyester resin (A1) does not gel. It is also possible to make it easier to increase the molecular weight. When the polyfunctional compound is copolymerized, the copolymerization amount is preferably 0.1 mol% or more, more preferably 0.2 mol% or more, when the total copolymerization component is 100 mol%. .. The upper limit is preferably 2 mol% or less, more preferably 1 mol% or less. Further, the polyester resin (A1) used in the present invention can be subjected to an addition modification reaction (post-addition) of an acid compound such as trimellitic acid at the molecular end after the completion of the polymerization reaction to add an acid value. By adding the acid compound to the end of the molecule, unsaturated polyvalent carboxylic acid is added to facilitate water-based dispersion after the acid-modified polyester resin (B) is obtained, and the storage stability of the produced aqueous-based dispersion is stable. Can be improved. When the total copolymerization component is 100 mol%, the copolymerization amount in the case of copolymerizing the acid compound is preferably 0.1 mol% or more, more preferably 0.2 mol% or more. The upper limit is preferably 2 mol% or less, more preferably 1 mol% or less.

Further, the polyester resin (A1) can be copolymerized with a lactone-based monomer at an arbitrary copolymerization ratio in a random or block shape. Examples of these lactone-based monomers include α-acetolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, and ε-caprolactone. Of these, ε-caprolactone is versatile and copolymerizable. Is preferable.

The polymerization of the polyester resin (A1) can be synthesized by a conventionally well-known method. As an example, an oligomer is prepared by subjecting an esterification reaction with the acid component and an excess amount of the glycol component to the acid component in advance, and then the glycol component is removed under high temperature and high vacuum. This completes the polymerization reaction. The acid component may be an alkyl ester compound and a transesterification reaction may be carried out. As the polymerization catalyst, commonly used compounds such as titanium-based, zinc-based, antimony-based, magnesium-based, germanium-based, and aluminum-based compounds can be used.
Next, it is preferable to carry out a modification addition reaction of the unsaturated polyvalent carboxylic acid component. By performing such a polymerization and modification method, a modified polyester resin having a functional group grafted on a side chain other than the polymer terminal can be obtained.

The acid value of the polyester resin (A1) is preferably 200 equivalents / ton or less, more preferably 150 equivalents / ton or less, and further preferably 100 equivalents / ton or less. In order to obtain an additional amount (acid value) exceeding 200 equivalents / ton, it is necessary to lower the molecular weight in order to increase the number of terminal groups of the polyester resin (A1), and the cohesive force of the resulting resin is insufficient. Sometimes. Alternatively, the risk of gelation increases due to the need to introduce a branching component having three or more functionalities. On the other hand, it is preferably 3 equivalents / ton or more, more preferably 10 equivalents / ton or more, still more preferably 30 equivalents / ton or more, and particularly preferably 50 equivalents / ton or more. Within the above range, an aqueous dispersion having no brittleness, excellent physical characteristics and adhesiveness of the coating film, and excellent storage stability can be obtained.

The number average molecular weight of the polyester resin (A1) is preferably 8,000 to 50,000, more preferably 15,000 to 30,000 in GPC analysis using a polystyrene standard sample. When the content is 8,000 or more, the cohesive force of the polyester resin (A1) is increased, and a good coating film can be obtained. On the other hand, when it is set to 50,000 or less, the viscosity in the molten state or the solution state does not become too high, and the modification addition reaction of the unsaturated polyvalent carboxylic acid becomes easy.

The glass transition temperature of the polyester resin (A1) is preferably −30 ° C. or higher, more preferably −20 ° C. or higher, and even more preferably −10 ° C. or higher. Further, it is preferably 80 ° C. or lower, more preferably 70 ° C. or lower, and further preferably 60 ° C. or lower. When the polyester resin (A1) has crystallinity, the melting point is preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and further preferably 160 ° C. or lower. Within the above range, the modification and addition reaction of the unsaturated polyvalent carboxylic acid becomes easy, and it becomes easy to obtain an aqueous dispersion having excellent biodegradability and storage stability.

<Polyester resin (A2)>
Examples of the polyester resin (A) used in the present invention include the polyester resin (A1) and the polyester resin (A2) in which aliphatic oxycarboxylic acids are used alone or copolymerized. Examples of the aliphatic oxycarboxylic acid include glycolic acid, lactic acid, glyceric acid, malic acid, tartaric acid, and a series of 3-hydroxyalkanoic acids that are raw materials for polyhydroxyalkanoic acid. These 3-hydroxyalkanoic acids are 3-hydroxybutanoic acid, 3-hydroxypentanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, and 3-hydroxydecanoic acid. , 3-Hydroxyundecanoic acid, 3-hydroxydodecanoic acid, 3-hydroxytridecanoic acid, 3-hydroxytetradecanoic acid, 3-hydroxypentadecylic acid, 3-hydroxyhexadecanoic acid and the like, and the polyester resin used in the present invention ( In A2), each of these raw material monomers may be used alone or in combination of two or more. Of these monomers, lactic acid, 3-hydroxybutanoic acid, and 3-hydroxycaproic acid are preferable from the viewpoint of versatility. Further, as lactic acid, a lactide compound obtained by dehydrating and dimerizing a lactic acid monomer may be used from the viewpoint of polymerization reactivity. As the polymerization reaction catalyst of these oxycarboxylic acids, a metal catalyst similar to that of the polyester (A1) can be used, and tin-based, cobalt-based, manganese-based, and iron-based catalysts can also be used.

The content of the aliphatic oxycarboxylic acid constituting the polyester resin (A2) is preferably 40 mol% or more with respect to the total amount of the monomers constituting the polyester resin (A2) from the viewpoint of biodegradability. It is more preferably 60 mol% or more, further preferably 80% or more, most preferably 90 mol% or more, and may be 100 mol% or more.

The preferred ranges of acid value, number average molecular weight, glass transition temperature, and melting point of the polyester resin (A2) are the same as those of the polyester resin (A1). Further, in addition to the aliphatic oxycarboxylic acid, a polyfunctional compound such as an aromatic dibasic acid, a glycol component having an aromatic ring, trimellitic propane, trimellitic acid, or trimellitic anhydride may be used, and the amount of copolymerization thereof. Is the same as that of the polyester resin (A1).

<Acid-modified polyester resin (B)>
The acid-modified polyester resin (B) is a resin having a structure in which an unsaturated polyvalent carboxylic acid is grafted as a side chain of the biodegradable polyester resin (A).

The addition reaction of the unsaturated polyvalent carboxylic acid can be carried out by a solution reaction in which the reaction is carried out in an organic solvent or a melting reaction using a twin-screw extruder. Of these, in the solution reaction, the unreacted unsaturated polyvalent carboxylic acid may be removed by reprecipitating the resin component of the product after the reaction using alcohol such as methanol, water, or a mixture thereof. I can.

Various radical initiator catalysts can be used as the reaction catalyst for the unsaturated polyvalent carboxylic acid addition reaction, but an organic peroxide catalyst is particularly preferable. Examples include di-tert-butylperoxyphthalate, tert-butylhydroperoxide, dicumyl peroxide, tert-butylcumyl peroxide, tert-butylperoxyisopropyl monocarbonate, 2,5-dimethyl-2, 5-Di (tert-butylperoxy) hexane, benzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxypivalate, methylethylketone peroxide, di- Peroxides such as tert-butyl peroxide and lauroyl peroxide; azonitriles such as azobisisobutyronitrile and azobisisopropionitrile are mentioned, and among these, di-tert-butyl peroxide and tert- Butylcumyl peroxide, tert-butylperoxyisopropyl monocarbonate, and 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane are preferable from the viewpoints of addition reaction efficiency, reaction start temperature, and ease of handling. ..

The acid value of the acid-modified polyester resin (B) of the present invention is preferably 150 equivalents / ton or more, more preferably 200 equivalents / ton or more, and further preferably 300 equivalents / ton or more. When the acid value is 150 equivalents / ton or more, it becomes easy to form a fine particle-like aqueous dispersion having excellent storage stability.

<Aqueous dispersion>
The aqueous dispersion of the present invention is a dispersion containing an acid-modified polyester resin (B), water, and if necessary, a basic substance. The resin concentration of the acid-modified polyester resin (B) in the aqueous dispersion is preferably 10% by mass or more, more preferably 20% by mass or more. Further, it is preferably 50% by mass or less, more preferably 40% by mass or less. If it is less than 10% by mass, the consumption of heat energy when producing a dry coating film is large, and if it exceeds 50% by mass, the viscosity of the dispersion becomes high and it becomes difficult to handle.

The basic substance is not particularly limited, but a volatile basic substance is preferable, and ammonia and organic amines are particularly preferable. The organic amines are not particularly limited, but are monomethylamine, dimethylamine, trimethylamine, monoethylamine, mono-n-propylamine, dimethyl-n-propylamine, monoethanolamine, diethanolamine, triethanolamine, N-methylethanol. Amine, N-aminoethylethanolamine, N-methyldiethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N, N-dimethylethanolamine, N, N-dimethylpropanolamine and the like are particularly preferable. Is triethylamine, N, N-dimethylethanolamine. These volatile amines can be used alone or in combination of two or more.

The basic substance is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and 2 parts by mass or more with respect to 100 parts by mass of the acid-modified polyester resin (B) of the present invention. It is more preferably present, and particularly preferably 3 parts by mass or more. Further, it is preferably 10 parts by mass or less, more preferably 9 parts by mass or less, further preferably 8 parts by mass or less, and particularly preferably 7 parts by mass or less. Within the above range, the particle size of the dispersed particles does not become too large, so that the storage stability is good. Further, a coating film having good water resistance can be obtained.

The average particle size of the aqueous dispersion particles of the present invention is preferably 500 nm or less, more preferably 400 nm or less, further preferably 300 nm or less, and particularly preferably 250 nm or less. The lower limit is not particularly limited, but industrially, there is no problem as long as it is 10 nm or more. Within the above range, the water dispersion is excellent in storage stability and easy to handle when used in paints, inks, coating agents, adhesives and the like.

The aqueous dispersion is preferably basic. The pH of the aqueous dispersion is preferably 6 or more, more preferably 6.5 or more, still more preferably 7 or more, and particularly preferably 7.5 or more. The upper limit is not particularly limited, but is 10 or less, more preferably 9.5 or less. Within the above range, the storage stability of the aqueous dispersion is good.

The viscosity of the aqueous dispersion is preferably 5 mPa · s or more, more preferably 10 mPa · s or more. Further, it is preferably 50 mPa · s or less, and more preferably 40 mPa · s or less. Within the above range, the water dispersion is excellent in storage stability and easy to handle when used in paints, inks, coating agents, adhesives and the like.

It is preferable that the aqueous dispersion of the present invention contains substantially no emulsifier. The term "substantially free of emulsifier" means that the emulsifier is 5% by mass or less, preferably 1% by mass or less, more preferably 0.5% by mass or less, and particularly preferably. Is 0.1% by mass or less, and may be 0% by mass. The water resistance of the coating film is improved by substantially containing no emulsifier.

The method for producing the aqueous dispersion of the present invention is not particularly limited, but is limited to a water-soluble ketone solvent such as methyl ethyl ketone (MEK) and water, or tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxane, 1, The acid-modified polyester resin (B) is heat-dissolved or swollen in a water-soluble ether solvent such as 3-dioxolane and water, a basic substance is added thereto, and the ketone solvent or the ether solvent is removed after cooling. It is possible to obtain a stable aqueous dispersion that does not contain an organic solvent substantially without using an emulsifier. "Substantially free of organic solvent" means that the content of organic solvent in the aqueous dispersion is 1% by mass or less.

The aqueous dispersion of the present invention can contain a small amount of a water-soluble organic solvent for the purpose of improving the film-forming characteristics when applied to the substrate and the storage stability of the aqueous dispersion. Examples of the water-soluble organic solvent include monoalkyl ethers of various alkylene glycols. Among them, ethylene glycol monobutyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether are preferable from the viewpoint of film forming properties and drying property. The content of these water-soluble organic solvents is preferably 1% by mass or more, more preferably 5% by mass or more, preferably 20% by mass or less, and more preferably 15% by mass in the aqueous dispersion. It is as follows.

The aqueous dispersion of the present invention contains various curing agents and curing reaction catalysts for the purpose of improving coating strength, solvent resistance, heat resistance, and base material adhesive strength as long as the biodegradability is not impaired. However, it can be used as a coating agent or an adhesive. Examples of the curing agent include a polyfunctional epoxy compound, a compound of a polyfunctional epoxy compound and an oxazoline compound and / or an anhydride compound, or a polyfunctional isocyanate compound. As the curing reaction catalyst, a general catalyst such as an organic amine type or an organic phosphorus type is effective for the polyfunctional epoxy compound. For polyfunctional isocyanate compounds, general organic tin-based, organic bismuth-based, organic amine-based, etc. are effective, but the curing reaction proceeds even without a catalyst.

The polyfunctional epoxy resin is not particularly limited as long as it has two or more epoxy groups in one molecule. Specifically, for example, glycidyl ether of bisphenol-A and its oligomer, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, Kohaku. Acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether , Polyalkylene glycol diglycidyl ethers, trimellitic acid triglycidyl ester, triglycidyl isocyanurate, 1,4-glycidyloxybenzene, diglycidyl propylene urea, glycerol triglycidyl ether, trimethylol ethane triglycidyl ether, trimethylol propane Examples thereof include triglycidyl ether, pentaerythritol tetraglycidyl ether, and triglycidyl ether as a glycerol alkylene oxide adduct. These can be used alone or in combination of two or more.

The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups in one molecule. Specifically, although not particularly limited, there are aromatic, alicyclic, and aliphatic polyisocyanate compounds, and any of low molecular weight type and high molecular weight type may be used. For example, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydride diphenylmethane diisocyanate, xylylene diisocyanate, hydride xylylene diisocyanate, isophorone diisocyanate, or trimerics of these isocyanate compounds, and the above-mentioned isocyanate compounds and ethylene glycol. , Trimethylol propane, propylene glycol, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, polyester polyols, polyether polyols, polyamides and other active hydrogen compounds. Can be mentioned. These can be used alone or in combination of two or more.

The curing agent is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and 8 parts by mass or more with respect to 100 parts by mass of the acid-modified polyester resin (B) of the present invention. Is even more preferable. Further, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 30 parts by mass or less. Within the above range, the hardness, toughness, adhesion strength and flexibility of the coating film obtained from the aqueous dispersion are improved.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. In the examples and comparative examples, the term "part" simply indicates a part by mass. The measurement and evaluation methods adopted in this specification are as follows.

(1) Number average molecular weight Using gel permeation chromatography (GPC) 150C manufactured by Waters, measurement was performed at a flow rate of 1 ml / min using tetrahydrofuran as a carrier solvent. As a column, three Shodex KF-802, KF-804, and KF-806 manufactured by Showa Denko KK were connected, and the column temperature was set to 30 ° C. A polystyrene standard material was used as the molecular weight standard sample.

(2) Acid value of biodegradable polyester resin (A) 0.2 g of biodegradable polyester resin (A) was dissolved in 20 ml of chloroform, and then measured with a 0.1 N-NaOH ethanol solution using phenolphthalein as an indicator. The measured value is shown by the equivalent in 1 ton of resin solid content.

(3) Glass transition temperature 5 mg of the sample is placed in an aluminum sample pan and sealed, and the temperature rises to 200 ° C. at a temperature rise rate of 20 ° C./min using a differential scanning calorimeter DSC-220 manufactured by Seiko Instruments Co., Ltd. It was measured and determined by the temperature at the intersection of the extension of the baseline below the glass transition temperature and the tangent showing the maximum slope at the transition.

(4) Resin composition analysis of polyester resins (A1) and (A2) The resin was dissolved in chloroform-d, and the resin was subjected to ¹ H-NMR using a nuclear magnetic resonance analyzer (NMR) "MR-400" manufactured by Varian. The composition ratio was determined.

(5) Confirmation of addition of unsaturated polyvalent carboxylic acid graft of acid-modified polyester resin (B) Confirmation of whether or not it is an acid adduct is described below using LC-9210NEXT (prepared GPC) manufactured by Nippon Analytical Industry Co., Ltd. The components having a number average molecular weight of 1000 or more were fractionated under the above conditions, and ¹ H-NMR and HMBC spectral analysis were performed.
<Preliminary GPC: LC-9210NEXT analysis conditions>
Column: 1 JAIGEL-2H, 1 JAIGEL-1H in series Detector: RI detector and UV detector (detection wavelength: 254 nm)
Sample: Chloroform 4 ml solution in which 100 mg of acid-modified polyester resin (B) is dissolved Injection amount: 3 ml
Developing solvent: Chloroform <preparation procedure and NMR, HMBC measurement procedure>
An acid-modified polyester resin (B) having a molecular weight of 1000 or more was separated based on a calibration curve prepared using a polystyrene standard sample. After the preparative solution was dried by spraying nitrogen, it was redissolved in chloroform-d or chloroform-d / DMSO (dimethyl sulfoxide) -d (1/1 vol ratio), and ¹ H-NMR measurement and ¹ H- ¹³ C- HMBC measurements were performed.
As a measuring device, an NMR device AVANCE-NEO600 manufactured by BRUKER was used. In ¹ H-NMR measurement, 30 mg of the preparative solution was dissolved in 0.6 ml of the above-mentioned solvent, and then the solution was filled in an NMR tube to perform ¹ H-NMR measurement. Chloroform-d or DMSO-d was used as the lock solvent, the waiting time was 1 second, the uptake time was 4 seconds, and the number of integrations was 64 times.
The CH ₂ and CH peaks at the α-position of the carbonyl bond of maleic acid and itaconic acid after addition are 2 to 3.5 ppm in ¹ H-NMR when the peak of chloroform is 7.28 ppm or the peak of DMSO is 2.5 ppm. It is detected as a broad peak in the region of. If a corresponding peak is confirmed in a preparative component having a molecular weight of 1000 or more, and then a correlation peak is confirmed between the peak and the C = O-derived peak near 173 ppm in ¹³ C-NMR from the HMBC spectrum, acid addition is performed. I judged it to be a body.
In addition, HMBC refers to Heteronuclear Multiple Bond Coherence, which is a measurement method of two-dimensional NMR.

(6) Quantification of the amount of unsaturated polyvalent carboxylic acid added to the acid-modified polyester resin (B) The acid value of the purified acid-modified polyester resin (B) reprecipitated in methanol was measured according to the above-mentioned (2) acid value measuring method. The added amount was calculated from the measured acid value * using the following formula.
Maleic anhydride added amount (% by mass) = (measured acid value * -acid value of biodegradable polyester resin (A)) x 99 ÷ (2 x ¹⁰⁶ )
Addition of anhydrous itaconic acid (mass%) = (measured acid value * -acid value of biodegradable polyester resin (A)) x 113 ÷ (2 x ¹⁰⁶ )

(7) Measurement of Viscosity of Aqueous Dispersion Using "Vicometer TV-22" (E-type viscometer) manufactured by Toki Sangyo Co., Ltd., 0.6 g of the aqueous dispersion sample was subjected to rotor No. The measurement was performed under the conditions of 0.8 ° (= 48') × R24, range H, rotation speed 5 rpm, and 25 ° C.

(8) Measurement of pH of aqueous dispersion Using "pH meter F-52" manufactured by HORIBA, Ltd., the value at 25 ° C. was measured. The measuring instrument is calibrated by Wako Pure Chemical Industries, Ltd., phthalate pH standard solution (pH: 4.01), neutral phosphate pH standard solution (pH: 6.86), borate pH standard. A three-point measurement was carried out using a solution (pH 9.18).

(9) Measurement of average particle size of aqueous dispersion Using "FPAR-1000" manufactured by Otsuka Electronics Co., Ltd., an aqueous dispersion sample prepared to a resin concentration of 0.05 g / L was measured three times at 25 ° C. The average value was used. The average particle size is the cumulant average particle size.

(10) Measurement of solid content concentration of the aqueous dispersion Take about 1 g of a sample of the aqueous dispersion in a 50 ml glass weighing bottle and weigh it precisely. Next, the weighing bottle from which the sample was collected is dried in a hot air dryer at 120 ° C. for 2 hours, and the removed weighing bottle is placed in a desiccator and left at room temperature for 30 minutes to cool. The weighing bottle is taken out from the desiccator, the mass is precisely weighed, and the mass% of the solid content concentration of the aqueous dispersion is calculated from the mass change before and after hot air drying (the following formula).
Aqueous dispersion solid content concentration (mass%) = (sample mass after hot air drying) / (sample mass before hot air drying) × 100

(11) Evaluation of storage stability of the aqueous dispersion The aqueous dispersion was stored at 25 ° C. for 3 months in a stationary state, and changes in the average particle size, pH and molecular weight of the aqueous dispersion with time were observed. The measurement results are shown in Table 3.

(14) Measurement of HAZE value of the coated film The aqueous dispersion was applied to a 25 μm thick PET film with a dry thickness of 5 μm, and the HAZE value was measured with a haze meter manufactured by Nippon Denshoku Kogyo Co., Ltd., NDH 7000II. The numerical value was the average value of the measured values of n = 5. The measurement results are shown in Table 4.

Below are examples of synthesis and comparative synthesis of the acid-modified polyester resin (B) used in Examples and Comparative Examples of the present invention and their aqueous dispersions.

Hereinafter, the abbreviations of the compounds shown in the table in the examples indicate the following compounds, respectively.
T: Terephthalic acid I: Isophthalic acid CHDA: 1,4-Cyclohexanedicarboxylic acid SA: Sebacic acid AA: Adipic acid TMA: Trimellitic anhydride NPG: Neopentyl glycol CHDM: 1,4-bis (hydroxymethyl) cyclohexane EG: Ethylene glycol 2MG: 2-methyl-1,3-propylene glycol MPD: 3-methyl-1,5-pentanediol 1,6-HD: 1,6-hexanediol 1,4-BD: 1,4-butanediol LLD: L-lactide DLD: D-lactide

[Synthesis of acid-modified polyester resin (B)]
Synthesis example 1
[Polyester resin (A-1) polymerization]
A 1L 4-neck flask equipped with a stir bar, a thermometer, and a Liebig condenser was charged with 155 parts of dimethyl terephthalate, 360 parts of 1,4-butanjiol, and 0.2 parts of tetra-n-butyl titanate as a catalyst, 190 parts. The transesterification reaction was carried out at ° C. to 230 ° C. for 3 hours. After confirming that a predetermined amount of methanol was distilled off, the reaction temperature was cooled to 180 ° C. 138 parts of 1,4-cyclohexanedicarboxylic acid and 58 parts of adipic acid were charged, and the reaction temperature was raised to 230 ° C. Next, the reaction temperature was gradually raised to 250 ° C. while distilling off the generated condensed water under normal pressure, and when the distillate of water was almost eliminated, the reaction temperature was gradually raised and the degree of decompression was gradually lowered. Finally, the temperature reached 270 ° C. and 3 Torr in 1 minute, and the polymerization reaction was completed. The inside of the reaction system was returned to normal pressure, and the melted copolymerized polyester resin was taken out from the flask into a heat-resistant bat, and the resin composition, number average molecular weight, acid value, melting point, and glass transition temperature were measured. The obtained measurement results are specified in Table 1 together with the number average molecular weight: 22000, acid value: 8 equivalents / ton, melting point: 108 ° C., glass transition temperature: -12 ° C., and resin composition analysis results.

[Saturated polyvalent carboxylic acid addition reaction to polyester resin (A-1)]
A four-necked flask with an internal volume of 1 L equipped with a stirring rod, a thermometer, and a condenser was charged with 100 parts of the copolymerized polyester resin (A-1) crushed into flakes, 140 parts of xylene, and 24 parts of anhydrous itaconic acid. The inside of the system was replaced with nitrogen. The temperature inside the flask was raised to 120 ° C. while stirring slowly, and the mixture was stirred for 1 hour to dissolve the polyester resin (A-1) and itaconic anhydride. Next, 4 parts of di-tert-butyl peroxide was added, and the temperature in the reaction system was raised to 140 ° C. while stirring at high speed. After reacting at 140 ° C. for 4 hours, the mixture was cooled, and when the temperature dropped to 100 ° C. or lower, it was gradually poured into a 1 L conical beaker containing 630 parts of methanol with vigorous stirring to precipitate the resin component. After stirring as it was for 30 minutes, the precipitated resin component was taken out into a vat, crushed into flakes and dried under a nitrogen stream to obtain an acid-modified polyester resin (B-1). It was confirmed that itaconic anhydride was added, the added amount was quantified, and the number average molecular weight was measured. As a result, it was confirmed that itaconic anhydride was added, and the quantitative value of the added amount was 4.8% by mass, the acid value was 840 equivalents / ton, and the number average molecular weight was 29000. These results are shown in Table-2.

Synthesis example 2
[Polyester resin (A-2) polymerization]
93 parts of dimethyl terephthalate, 78 parts of dimethyl isophthalate, 55 parts of neopentyl glycol, 60 parts of ethylene glycol, and tetra-n-butyl titanate 0 as a catalyst in a 1L 4-neck flask equipped with a stirring rod, a thermometer, and a Liebig condenser. .1 part was charged and transesterification reaction was carried out at 190 ° C to 230 ° C for 3 hours. After confirming that a predetermined amount of methanol was distilled off, the reaction temperature was cooled to 180 ° C. 25 parts of sebacic acid was charged and the reaction temperature was raised to 230 ° C. Next, the reaction temperature was gradually raised to 250 ° C. while distilling off the generated condensed water under normal pressure, and when the distillate of water was almost eliminated, the reaction temperature was gradually raised and the degree of decompression was gradually lowered. Finally, the temperature reached 270 ° C. and 3 Torr in 1 minute, and the polymerization reaction was completed. The pressure inside the reaction system was returned to normal pressure, and the melted copolymerized polyester resin was taken out from the flask into a heat-resistant bat, and the resin composition, number average molecular weight, acid value, and glass transition temperature were measured. The obtained measurement results are specified in Table 1 together with the number average molecular weight: 20000, acid value: 3 equivalents / ton, glass transition temperature: 47 ° C., and resin composition analysis results.

[Addition reaction of unsaturated polyvalent carboxylic acid to polyester resin (A-2)]
In the reaction system, 100 parts of the polyester resin (A-2) crushed into flakes, 140 parts of xylene, and 23 parts of maleic anhydride were placed in a 4-necked flask having an internal volume of 1 L equipped with a stirring rod, a thermometer, and a condenser. Was replaced with nitrogen. The temperature inside the flask was raised to 120 ° C. while stirring slowly, and the mixture was stirred for 1 hour to dissolve the polyester resin (A-2) and maleic anhydride. Next, 4 parts of di-tert-butyl peroxide was added, and the temperature in the reaction system was raised to 140 ° C. while stirring at high speed. After reacting at 140 ° C. for 4 hours, the mixture was cooled, and when the temperature dropped to 100 ° C. or lower, it was gradually poured into a 1 L conical beaker containing 630 parts of methanol with vigorous stirring to precipitate the resin component. After stirring as it was for 30 minutes, the precipitated resin component was taken out into a vat, crushed into flakes and dried under a nitrogen stream to obtain an acid-modified polyester resin (B-2). Confirmation that maleic anhydride was added, quantification of the added amount, and measurement of the number average molecular weight were carried out. As a result, it was confirmed that maleic anhydride was added, and the quantitative value of the added amount was 2.0% by mass, the acid value was 400 equivalents / ton, and the number average molecular weight was 22000. These results are shown in Table-2.

Synthesis example 3
[Polyester resin (A-3) polymerization]
1.2 parts of 3-methyl-1,5-pentanediol, 320 parts of L-lactide, 80 parts of D-lactide, 200 parts of toluene and a reaction catalyst in a 1L 4-neck flask equipped with a stirring rod, a thermometer and a Leibich cooling tube. 0.2 part of tin octylate and 1 part of ethyldiethylphosphonoacetate were charged as a catalyst deactivating agent, and the reaction system was heated to 180 ° C while co-boiling and dehydrating toluene under a nitrogen gas stream for 3 hours at the same temperature. Stirred. The system was then depressurized to distill off unreacted residual monomers. The obtained polylactic acid resin was poured into a bat, and the number average molecular weight, acid value, and glass transition temperature were measured. The obtained measurement results are specified in Table 1 together with the number average molecular weight: 36000, acid value: 12 equivalents / ton, glass transition temperature: 48 ° C., and resin composition analysis results.

[Addition reaction of unsaturated polyvalent carboxylic acid to polyester resin (A-3)]
In the reaction system, 100 parts of the polyester resin (A-3) crushed into flakes, 140 parts of xylene, and 23 parts of maleic anhydride were charged in a 4-necked flask having an internal volume of 1 L equipped with a stirring rod, a thermometer, and a condenser. Was replaced with nitrogen. The temperature inside the flask was raised to 120 ° C. while stirring slowly, and the mixture was stirred for 1 hour to dissolve the polyester resin (A-3) and maleic anhydride. Next, 4 parts of di-tert-butyl peroxide was added, and the temperature in the reaction system was raised to 140 ° C. while stirring at high speed. After reacting at 140 ° C. for 4 hours, the mixture was cooled, and when the temperature dropped to 100 ° C. or lower, it was gradually poured into a 1 L conical beaker containing 630 parts of methanol with vigorous stirring to precipitate the resin component. After stirring as it was for 30 minutes, the precipitated resin component was taken out into a vat, crushed into flakes and dried under a nitrogen stream to obtain an acid-modified polyester resin (B-3). Confirmation that maleic anhydride was added, quantification of the added amount, and measurement of the number average molecular weight were carried out. As a result, it was confirmed that maleic anhydride was added, and the quantitative value of the added amount was 1.5% by mass, the acid value was 310 equivalents / ton, and the number average molecular weight was 34000. These results are shown in Table-2.

Comparative synthesis example 1
[Polyester resin (A-4) polymerization]
A 1L 4-neck flask equipped with a stir bar, a thermometer, and a Liebig condenser was charged with 155 parts of dimethyl terephthalate, 360 parts of 1,4-butanjiol, and 0.2 parts of tetra-n-butyl titanate as a catalyst, 190 parts. The transesterification reaction was carried out at ° C. to 230 ° C. for 3 hours. After confirming that a predetermined amount of methanol was distilled off, the reaction temperature was cooled to 180 ° C. 138 parts of 1,4-cyclohexanedicarboxylic acid and 58 parts of adipic acid were charged, and the reaction temperature was raised to 230 ° C. Next, the reaction temperature was gradually raised to 250 ° C. while distilling off the generated condensed water under normal pressure, and when the distillate of water was almost eliminated, the reaction temperature was gradually raised and the degree of decompression was gradually lowered. Finally, the temperature reached 270 ° C. and 3 Torr in 1 minute, and the polymerization reaction was completed. Next, the inside of the reaction system was returned to normal pressure, the temperature inside the system was cooled to 220 ° C. while enclosing nitrogen gas, and 2 parts of anhydrous trimellitic acid was added. While maintaining the temperature inside the system at 220 ° C., the mixture was stirred under a nitrogen atmosphere for 45 minutes to complete the addition reaction of trimellitic anhydride. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant bat, and the resin composition, number average molecular weight, acid value, melting point, and glass transition temperature were measured. The obtained measurement results are specified in Table 1 together with the number average molecular weight: 20000, acid value: 54 equivalents / ton, melting point: 102 ° C., glass transition temperature: -13 ° C., and resin composition analysis results.

Comparative synthesis example 2
[Polyester resin (A-5) polymerization]
116 parts of dimethyl terephthalate, 39 parts of dimethyl isophthalate, 97 parts of 1,4-bis (hydroxymethyl) cyclohexane, 2-methyl-1,3- in a 1L 4-neck flask equipped with a stir bar, a thermometer, and a Liebig condenser. 74 parts of propylene glycol and 0.1 part of tetra-n-butyl titanate as a catalyst were charged, and a transesterification reaction was carried out at 190 ° C. to 230 ° C. for 3 hours. After confirming that a predetermined amount of methanol was distilled off, the reaction temperature was cooled to 180 ° C. 33 parts of 1,4-cyclohexanedicarboxylic acid and 2 parts of trimellitic anhydride were charged, and the reaction temperature was raised to 230 ° C. Next, the reaction temperature was gradually raised to 250 ° C. while distilling off the generated condensed water under normal pressure, and when the distillate of water almost disappeared, the reaction temperature was gradually raised and the degree of decompression was gradually lowered to 30. Finally, the temperature reached 270 ° C. and 3 Torr in 1 minute, and the polymerization reaction was completed. Next, the inside of the reaction system was returned to normal pressure, the temperature inside the system was cooled to 220 ° C. while enclosing nitrogen gas, and 2 parts of anhydrous trimellitic acid was added. While maintaining the temperature inside the system at 220 ° C., the mixture was stirred under a nitrogen atmosphere for 45 minutes to complete the addition reaction of trimellitic anhydride. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant bat, and the resin composition, number average molecular weight, acid value, and glass transition temperature were measured. The obtained measurement results had a number average molecular weight: 24000, an acid value: 104 equivalents / ton, and a glass transition temperature: 55 ° C., which are specified in Table 1 together with the resin composition analysis results.

Comparative synthesis example 3
[Polyester resin (A-6) polymerization]
78 parts of dimethyl terephthalate, 62 parts of dimethyl isophthalate, 65 parts of 1,4-bis (hydroxymethyl) cyclohexane, 2-methyl-1,3- in a 1L 4-neck flask equipped with a stir bar, a thermometer, and a Leibich cooling tube. 41 parts of propylene glycol, 37 parts of ethylene glycol, and 0.1 part of tetra-n-butyl titanate as a catalyst were charged, and a transesterification reaction was carried out at 190 ° C. to 230 ° C. for 3 hours. After confirming that a predetermined amount of methanol was distilled off, the reaction temperature was cooled to 180 ° C. 26 parts of 1,4-cyclohexanedicarboxylic acid and 6 parts of trimellitic anhydride were charged, and the reaction temperature was raised to 230 ° C. Next, the reaction temperature was gradually raised to 250 ° C. while distilling off the generated condensed water under normal pressure, and when the distillate of water almost disappeared, the reaction temperature was gradually raised and the degree of decompression was gradually lowered. Finally, the temperature reached 270 ° C. and 3 Torr in 1 minute, and the polymerization reaction was completed. Next, the inside of the reaction system was returned to normal pressure, the temperature inside the system was cooled to 220 ° C. while enclosing nitrogen gas, and 6 parts of anhydrous trimellitic acid was added. While maintaining the temperature inside the system at 220 ° C., the mixture was stirred under a nitrogen atmosphere for 45 minutes to complete the addition reaction of trimellitic anhydride. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant bat, and the resin composition, number average molecular weight, acid value, and glass transition temperature were measured. The obtained measurement results had a number average molecular weight: 5500, an acid value: 370 equivalents / ton, and a glass transition temperature: 53 ° C., which are specified in Table 1 together with the resin composition analysis results.

Emulsified aqueous dispersions of unsaturated polyvalent carboxylic acid graft modified products obtained in the above synthetic examples and comparative synthetic examples were prepared, and the obtained aqueous dispersions were evaluated.

Example-1
50 parts of the acid-modified polyester resin (B-1) obtained in Synthesis Example 1, 100 parts of tetrahydrofuran, 30 parts of ethylene glycol monobutyl ether, and 15 parts of isopropyl alcohol were placed in a 1L 4-neck flask equipped with a thermometer, a stirring blade, and a condenser. It was charged and the resin component was uniformly dissolved at 60 ° C. Then, 160 parts of deionized water was gradually injected and stirred at the same temperature for 90 minutes. 18 parts of a 50% aqueous solution of dimethylethanolamine was added, and the mixture was cooled to 40 ° C. over 120 minutes with stirring. Next, the organic solvent component was distilled off at a reduced pressure of 91 kPa to obtain an aqueous dispersion (emulsion) E-1 having a solid content concentration of about 25% by mass. The average particle size, pH, viscosity, solid content concentration and number average molecular weight of E-1 were measured. As a result, the average particle size was 27 nm, the pH was 9.3, the viscosity was 10.6 mPa · s, the solid content concentration was 24.5% by mass, and the number average molecular weight was 27,000, which are shown in Table 3. In addition, changes over time after being left at 25 ° C for 3 months (standing) were measured and are also shown in the same table. In addition, E-1 was coated on a 25 μm thick PET film substrate so that the dry thickness was 5 μm, and the HAZE value was measured and specified separately in Table 4. The HAZE value was 5.4%.

Example-2
The acid-modified polyester resin (B-2) was dispersed in emulsified water by the same method as in Example-1 to obtain an aqueous dispersion (emulsion) E-2. The average particle size, pH, viscosity, solid content concentration and number average molecular weight of E-2 were measured. As a result, the average particle size was 73 nm, the pH was 9.0, the viscosity was 11.7 mPa · s, the solid content concentration was 25.2 mass%, and the number average molecular weight was 20000, which are shown in Table 3. In addition, changes over time after being left at 25 ° C for 3 months (standing) were measured and are also shown in the same table. Further, the HAZE value of the coated film of E-2 prepared in the same manner as in Example 1 was measured, and the results are separately specified in Table 4. The HAZE value was 3.9%.

Example-3
The acid-modified polyester resin (B-3) was dispersed in emulsified water by the same method as in Example 1 to obtain an aqueous dispersion (emulsion) E-3. The average particle size, pH, viscosity, solid content concentration and number average molecular weight of E-3 were measured. As a result, the average particle size was 183 nm, the pH was 9.4, the viscosity was 9.0 mPa · s, the solid content concentration was 23.8 mass%, and the number average molecular weight was 33000, which are shown in Table 3. In addition, changes over time after being left at 25 ° C for 3 months (standing) were measured and are also shown in the same table. Further, the HAZE value of the coated film of E-3 prepared in the same manner as in Example 1 was measured, and the results are separately specified in Table 4. The HAZE value was 4.1%.

Comparative Examples-1 and 2
Using the polyester resins (A-4) and (A-5) obtained in Comparative Synthesis Examples-1 and 2, respectively, an attempt was made to disperse the emulsified water in the same manner as in Example 1, but in any case. However, no aqueous dispersion was obtained.

Comparative Example-3
Seven parts of a 50% aqueous solution of dimethylethanolamine was added to the polyester resin (A-6) in the same manner as in Example 1 and dispersed in emulsified water to obtain an aqueous dispersion (emulsion) E-4. The average particle size, pH, viscosity, solid content concentration and number average molecular weight of E-4 were measured. As a result, the average particle size was 87 nm, the pH was 9.1, the viscosity was 7.3 mPa · s, the solid content concentration was 31.8% by mass, and the number average molecular weight was 6500, which are shown in Table 3. In addition, changes over time after being left at 25 ° C for 3 months (standing) were measured and are also shown in the same table. Further, an attempt was made to prepare a coat film by the same method as in Example 1, but the film-forming property was insufficient and the film was not formed.

In Comparative Examples 1 and 2, since the modification treatment for graft-adding the unsaturated polyvalent carboxylic acid to each of the polyester resins (A-4) and (A-5) was not performed, a sufficient hydrophilic polar group was introduced. It was not possible to form an emulsified aqueous dispersion. Further, in Comparative Example 3, the polyester resin (A-6) was not modified by graft-adding an unsaturated polyvalent carboxylic acid, but it had a low molecular weight and a highly branched molecular structure, and was hydrophilic for dispersion of emulsified water. The amount of sexual polar groups has been introduced. However, since the molecular weight was low, film-forming properties could not be obtained, and a coat film could not be formed on the PET film substrate. On the other hand, as can be seen from Table 3, in Examples 1 to 3, fine particle-like aqueous dispersions having excellent storage stability can be obtained. Further, as can be seen from Table 4, a highly transparent coat film could be formed from any of the dispersions.

The unsaturated polyvalent carboxylic acid graft-modified biodegradable polyester resin of the present invention can form an emulsified aqueous dispersion having excellent storage stability with fine particles without using an emulsifier. Therefore, it is useful as an environment-friendly paint, ink, coating agent, adhesive, etc., and can exhibit excellent features in the working environment at the time of painting, printing, adhesion, and coating.

Claims

An aqueous dispersion of an acid-modified polyester resin (B) having a structure in which an unsaturated polyvalent carboxylic acid is grafted as a side chain of the biodegradable polyester resin (A).
The aqueous dispersion according to claim 1, wherein the acid value of the acid-modified polyester resin (B) is 150 equivalents / ton or more.
The aqueous dispersion according to claim 1 or 2, wherein the unsaturated polyvalent carboxylic acid is at least one selected from the group consisting of maleic acid, itaconic acid, and anhydrides thereof.
The biodegradable polyester resin (A) is at least one selected from the group consisting of aliphatic dibasic acid and aliphatic dibasic acid, and one or more selected from the group consisting of aliphatic glycol and aliphatic glycol. The aqueous dispersion according to any one of claims 1 to 3, which is a polyester resin (A1) having an aliphatic oxycarboxylic acid as a structural unit or a polyester resin (A2) having an aliphatic oxycarboxylic acid as a structural unit.
The total amount of the polyester resin (A1) including the aliphatic dibasic acid, the alicyclic dibasic acid, the aliphatic glycol and the alicyclic glycol is 50 mol with respect to the total amount of the monomers constituting the polyester resin (A1). 40% or more, or the aqueous dispersion according to claim 4, wherein the polyester resin (A2) has 40 mol% or more based on the total amount of the monomers constituting the polyester resin (A2). ..
The aqueous dispersion according to any one of claims 1 to 5, wherein the aqueous dispersion contains an acid-modified polyester resin (B) and an organic amine compound.
The aqueous dispersion according to any one of claims 1 to 6, which contains substantially no emulsifier.
A coating agent containing the aqueous dispersion according to any one of claims 1 to 7.
An adhesive containing the aqueous dispersion according to any one of claims 1 to 7.