JP7105050B2 - Freeze-thaw stability improver and adhesion improver - Google Patents

Description

TECHNICAL FIELD The present invention relates to a freeze-thaw stability improver, and more specifically to an agent for improving the freeze-thaw stability of a polymer emulsion obtained by emulsion polymerization of a monomer.

Conventional methods for producing polymers such as acrylic acid ester polymers, ethylene-vinyl acetate copolymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, etc., by emulsion polymerization methods using various surfactants. is proposed. For example, anionic surfactants such as long-chain alkyl sulfates, long-chain alkylbenzenesulfonates, polyoxyethylene alkylphenyl ether sulfates, alkyldiphenyl ether disulfonates, or polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers , polyoxyethylene fatty acid esters, and Pluronic (registered trademark) type surfactants.

Originally, surfactants used in the production of polymer emulsions not only participate in the polymerization initiation reaction and polymer formation reaction, but also stabilize the polymer emulsion during polymerization, the conversion rate of the monomer, and the generated It is deeply involved in the mechanical stability, chemical stability, freeze-thaw stability, pigment miscibility and storage stability of polymer emulsions. In addition, it has a great influence on physical properties such as the particle size, viscosity, and foamability of the polymer particles in the emulsion. Therefore, it is important to select a surfactant suitable for the application. be.

For example, Patent Document 1 discloses an emulsifier for emulsion polymerization having an ion-binding salt having a reactive group. By using this surfactant, sufficient polymerization stability can be obtained during emulsion polymerization, and thermoplastic It is disclosed that the water resistance and weather resistance of the resin could be improved.

WO2013/129492

However, according to the studies of the present inventors, when the surfactant disclosed in Patent Document 1 is used, the polymer cannot achieve sufficient freeze-thaw stability in the state of emulsion, and the polymer and It was found that sufficient adhesion to the substrate could not be achieved in some cases.

Accordingly, an object of the present invention is to provide a freeze-thaw stability improver capable of improving the freeze-thaw stability of polymer emulsions. Another object of the present invention is to provide an adhesion improver capable of improving the adhesion between the polymer derived from the polymer emulsion and a substrate.

As a result of intensive studies, the inventors of the present invention have found that the above problems can be solved by the following means, and have completed the present invention.

That is, one aspect of the present invention relates to a freeze-thaw stability improver for polymer emulsions (hereinafter also simply referred to as "freeze-thaw stability improver") containing a compound represented by the following general formula (1). :

In general formula (1), Q ⁺ is a nitrogen-containing compound cation,
A is a linear or branched alkylene group having 2 to 4 carbon atoms,
m represents the average number of added moles of AO and is a number from 1 to 150,
Y is a single bond or a linear or branched alkylene group having 1 to 5 carbon atoms,
R ₁ is a hydrogen atom or a methyl group,
R ₂ is a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 25 carbon atoms, or a group represented by the following general formula (2);
l is an integer from 1 to 3,

In general formula (2), R ₃ and R ₄ each independently represent a hydrogen atom or a methyl group, and * represents a connecting point.

Furthermore, another aspect of the present invention relates to an adhesion improver between a polymer and a substrate (hereinafter also simply referred to as an "adhesion improver") containing a compound represented by the general formula (1). .

According to the present invention, it is possible to further improve the freeze-thaw stability of a polymer emulsion obtained by emulsion polymerization and the adhesion between a polymer derived from the polymer emulsion and a substrate.

Embodiments of the present invention will be described below.

The freeze-thaw stability improver and adhesion improver according to the present invention contain a compound represented by the following general formula (1) as an active ingredient.

In general formula (1), Q ⁺ is a nitrogen-containing compound cation,
A is a linear or branched alkylene group having 2 to 4 carbon atoms,
m represents the average number of added moles of AO and is a number from 1 to 150,
Y is a single bond or a linear or branched alkylene group having 1 to 5 carbon atoms,
R ₁ is a hydrogen atom or a methyl group,
R ₂ is a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 25 carbon atoms, or a group represented by the following general formula (2);
l is an integer from 1 to 3,

In general formula (2), R ₃ and R ₄ are each independently a hydrogen atom or a methyl group, preferably at least one of R ₃ and R ₄ is a methyl group, and * represents a connecting point. .

Examples of linear or branched alkylene groups having 2 to 4 carbon atoms used as A in the general formula (1) include ethylene group, propylene group and butylene group. Ethylene group and propylene group are particularly preferable from the viewpoint of availability.

m in the general formula (1) is a number from 1 to 150. m is preferably 1 to 50, more preferably 5 to 50, from the viewpoint of ease of handling due to a decrease in viscosity, etc., or interfacial properties.

Examples of linear or branched alkylene groups having 1 to 5 carbon atoms used as Y in the general formula (1) include methylene group, ethylene group, propylene group, and butylene group. be done. From the standpoint of availability, a methylene group, an ethylene group, and a propylene group are particularly preferred.

Examples of substituted or unsubstituted linear, branched or cyclic alkyl groups having 1 to 25 carbon atoms used as R ₂ in the general formula (1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isoamyl group, tert-pentyl group, neopentyl group, n-hexyl group, 3- methylpentan-2-yl group, 3-methylpentan-3-yl group, 4-methylpentyl group, 4-methylpentan-2-yl group, 1,3-dimethylbutyl group, 3,3-dimethylbutyl group, 3,3-dimethylbutan-2-yl group, n-heptyl group, 1-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 1-ethylpentyl group, 1-( n-propyl)butyl group, 1,1-dimethylpentyl group, 1,4-dimethylpentyl group, 1,1-diethylpropyl group, 1,3,3-trimethylbutyl group, 1-ethyl-2,2-dimethyl propyl group, n-octyl group, 2-methylhexan-2-yl group, 2,4-dimethylpentan-3-yl group, 1,1-dimethylpentan-1-yl group, 2,2-dimethylhexane-3 -yl group, 2,3-dimethylhexan-2-yl group, 2,5-dimethylhexan-2-yl group, 2,5-dimethylhexan-3-yl group, 3,4-dimethylhexan-3-yl group, 3,5-dimethylhexan-3-yl group, 1-methylheptyl group, 2-methylheptyl group, 5-methylheptyl group, 2-methylheptan-2-yl group, 3-methylheptan-3-yl group, 4-methylheptan-3-yl group, 4-methylheptan-4-yl group, 1-ethylhexyl group, 2-ethylhexyl group, 1-propylpentyl group, 2-propylpentyl group, 1,1-dimethylhexyl group, 1,4-dimethylhexyl group, 1,5-dimethylhexyl group, 1-ethyl-1-methylpentyl group, 1-ethyl-4-methylpentyl group, 1,1,4-trimethylpentyl group, 2, 4,4-trimethylpentyl group, 1-isopropyl-1,2-dimethylpropyl group, 1,1,3,3-tetramethylbutyl group, n-nonyl group, 1-methyloctyl group, 6-methyloctyl group, 1-ethylheptyl group, 1-(n-butyl)pentyl group, 4-methyl-1-(n-propyl)pentyl group, 1,5,5-trimethylhexyl group, 1,1,5 -trimethylhexyl group, 2-methyloctan-3-yl group, n-decyl group, 1-methylnonyl group, 1-ethyloctyl group, 1-(n-butyl)hexyl group, 1,1-dimethyloctyl group, 3 , 7-dimethyloctyl group, n-undecyl group, 1-methyldecyl group, 1-ethylnonyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, 1-methyltridecyl group, n-pentadecyl group, n -hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group and the like. Here, fluorine, chlorine, bromine, iodine and the like can be mentioned as substituents for the substituted linear, branched or cyclic alkyl group having 1 to 25 carbon atoms. Among them, from the viewpoint of availability, substituted or unsubstituted methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-hexyl group, branched octyl group (2-ethylhexyl group, 1,1,3,3-tetramethylbutyl group, etc.), branched nonyl group (1-methyloctyl group, 6-methyloctyl group, 1-ethylheptyl group, etc.), branched A tridecyl group and a branched tridecyl group are preferable, and a tert-butyl group, a branched octyl group, a branched nonyl group and a branched dodecyl group are more preferable. In addition, long-chain alkyl groups such as nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group and tetradecyl group are branched or a mixture of linear and branched (mixture of structural isomers). These forms are also within the scope of the present invention.

Examples of nitrogen-containing compound cations used as Q ⁺ in the general formula (1) include ammonium ions, primary ammonium ions, secondary ammonium ions, tertiary ammonium ions, quaternary ammonium ions, imidazolium ion, pyridinium ion, pyrrolidinium ion, piperidinium ion, quinolinium ion, morpholinium ion, imidazolidinonium ion (ethylene urea), and the like.

Among them, examples of tertiary ammonium ions include nitrogen-containing compound cations represented by the following general formula (3):

In general formula (3), R ₅ and R ₆ are each independently a linear or branched alkyl group having 1 to 4 carbon atoms, and R ₇ is a linear or branched alkyl group having 2 to 4 carbon atoms. It is a branched alkylene group, X is an oxygen atom or NH, and _R8 is a hydrogen atom or a methyl group.

Examples of linear or branched C 1-4 alkyl groups used as R ₅ and R ₆ in the general formula (3) include methyl, ethyl, propyl and butyl. and the like. From the standpoint of availability, a methyl group, an ethyl group, and a butyl group are particularly preferred.

Examples of linear or branched alkylene groups having 2 to 4 carbon atoms that can be used as R ₇ in general formula (3) include ethylene, propylene and butylene groups. Ethylene group and propylene group are particularly preferable from the viewpoint of availability.

More preferable compounds for the freeze-thaw stability improver or adhesion improver represented by the general formula (1) include compounds represented by the following chemical formulas (4) to (7).

In chemical formulas (4) to (7), R ₁ , R ₂ , R ₅ to R ₈ , X, Y, A, m and l are defined as described above.

The method for producing the compound, which is the active ingredient of the freeze-thaw stability improver or adhesion improver, is not particularly limited, and examples thereof include an anion exchange method, neutralization method, and acid ester method. In addition, a deammonification method of obtaining an ion-bonding salt having a reactive group by reacting an ammonium salt of a sulfate ester or an ammonium sulfonate with a nitrogen-containing compound to distill off ammonia is also preferably used.

Hereinafter, freeze-thaw stability improvers and adhesion improvers, which are applications of the above compounds, will be described in detail.

(emulsion polymerization)
The method of using the freeze-thaw stability improver or adhesion improver is not particularly limited. It is possible to contribute to the purpose of improving the adhesiveness between the polymer, which is the dried product of the polymer emulsion, and the substrate. There are no particular restrictions on the specific form in which these agents (compounds) are added to the reaction system during emulsion polymerization. and the like.

When the freeze-thaw stability improver or adhesion improver according to the present invention is used and a polymer obtained by emulsion polymerization or the like is used to produce a molded article, the polymer emulsion obtained by emulsion polymerization exhibits excellent freezing properties. It can have melt stability. In addition, molded articles manufactured using the polymer emulsion can have excellent adhesion to substrates. The effect of improving the freeze-thaw stability of the polymer emulsion is only speculation, but it is due to the inclusion of a specific type of compound having a bulky hydrophobic group (for example, a polycyclic structure) as an active ingredient. it is conceivable that. Specifically, during the thawing stage of the freeze-thaw process in polymer emulsions, polymer particles with a high Tg tend to return to their normal state, while particles with a relatively low Tg are in a gelled aggregated state or coalesced state. It is difficult to recover from the state. The freeze-thaw stability improver according to the present invention can form a protective layer on the surface of the flexible polymer particles and stabilize the polymer particles to some extent based on the steric effect of relatively large hydrophobic groups. . Large hydrophobic groups adsorbed or grafted onto polymer particles or copolymerized into polymer particles prevent these polymer particles from accessing the surface of other flexible polymer particles, It is believed that the separation distance between flexible polymer particles can be increased.

The monomer (polymerizable monomer) that can be emulsion-polymerized using the freeze-thaw stability improver or adhesion improver according to the present invention is not particularly limited, and conventionally known polymerizable monomers can be used. methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc. acrylic acid or methacrylic acid esters; vinyl halides such as vinyl bromide, vinyl chloride and vinylidene chloride; vinyl esters of fatty acids such as acetic acid, propionic acid and tertiary synthetic saturated carboxylic acids: styrene, α - aromatic vinyls such as methylstyrene: monoolefins or conjugated diolefins such as ethylene and butadiene; vinyl cyanides such as acrylonitrile; α,β-unsaturated amides such as acrylamide: acrylic acid, methacrylic acid, itacon Acids, α,β-unsaturated carboxylic acids such as maleic acid and fumaric acid.

As the polymerization initiator, initiators usually used for emulsion polymerization can be used without particular limitation. ; organic peroxides such as benzoyl peroxide, di-t-butyl peroxide and peracetic acid; 2,2-azobisisobutyronitrile, 4-azobis-(4-cyanopentanoic) acid or alkali metals thereof A radical-generating polymerization initiator such as a salt can be used, and the amount used is preferably 0.01 to 3.0% by mass, more preferably 0.1 to 2.0% by mass, and more preferably 0.1 to 2.0%, based on the polymerizable monomer. It is preferably 0.1 to 1.0% by weight.

Further, when a peroxide is used as a polymerization initiator, if necessary, the peroxide can be used in combination with a reducing agent such as ascorbic acid, soluble sulfite, hydrosulfite, thiosulfate, etc. A metal monomer that generates heavy metal ions in water or a metal compound that generates metal ions in water, such as ferrous sulfate, can also be used in combination as a redox polymerization initiator.

Chain transfer agents can also be used in combination, such as t-dodecylmercaptan, dodecylmercaptan, carbon tetrachloride, chloroform, triphenylmethane, and the like.

Furthermore, additives commonly used in emulsion polymerization technology, such as chelating agents, buffers, salts of organic acids, solvents, etc., can be used. As the solvent, in addition to water, organic solvents such as alcohol, glycol, and glycol ether can be used, but water is preferably used as the solvent.

In addition, the compound represented by the general formula (1) is used not only for improving freeze-thaw stability or adhesion, but also for use as an emulsifier for emulsion polymerization or an antifoaming agent. Therefore, emulsion polymerization can be carried out using the freeze-thaw stability improver or adhesion improver according to the present invention. At that time, the freeze-thaw stability improver or adhesion improver according to the present invention may be used alone, or other emulsifiers for emulsion polymerization or additives may be used in combination.

In the emulsion polymerization using the freeze-thaw stability improver or the adhesion improver according to the present invention, the freeze-thaw stability improver or the adhesion improver represented by the general formula (1) sufficiently exhibits its function even by itself. However, if necessary, conventionally known surfactants, reactive emulsifiers, polymer emulsifiers, protective colloids, etc. can be used in combination. Surfactants that can be used in combination include, for example, anionic surfactants such as long-chain alkyl sulfates, polyoxyalkylene alkyl ether sulfates, long-chain alkylbenzene sulfonates, polyoxyalkylene alkylphenyl ether sulfates, and alkyldiphenyl ether disulfonic acids. Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene fatty acid esters, and Pluronic (registered trademark) type surfactants.

Examples of polymer emulsifiers that can be used in combination include polyvinyl alcohol, poly(meth)acrylates, polyhydroxyalkylene (meth)acrylates, etc. Protective colloids that can be used in combination include anionic protective colloids such as sodium alginate. , nonionic protective colloids such as hydroxyethyl cellulose, and the like.

The amount of the freeze-thaw stability improver or adhesion improver containing the compound represented by the general formula (1) according to the present invention is preferably 0.1 to 10 parts per 100 parts by mass of the polymerizable monomer. parts by mass, more preferably 0.3 to 5.0 parts by mass, and even more preferably 0.5 to 3.0 parts by mass. The freeze-thaw stability improver and the adhesion improver according to the present invention may contain only one compound represented by the general formula (1) alone, or may contain two or more kinds. good too. When two or more kinds of compounds are used in combination, the preferred usage amount mentioned above is the total usage amount of the above compounds. Another effect of the freeze-thaw stability improver or adhesion improver represented by the general formula (1) according to the present invention is that even a small amount of addition can sufficiently perform emulsion polymerization, and furthermore, the polymer emulsion can be obtained. It is excellent in freeze-thaw stability, low foaming property, etc., and can improve the adhesion between the polymer and the substrate.

The present invention also provides a polymer composition obtained by emulsion polymerization as described above. That is, according to another aspect of the present invention, there is provided a polymer composition containing the freeze-thaw stability improver or adhesion improver according to the present invention, a polymerizable monomer, and a solvent (especially preferably water). is also provided. Preferably, the polymer composition is in the form of an emulsion.

The present invention will be described in more detail with the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples. Unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass" respectively. Also, in the following examples, unless otherwise specified, the operations were carried out under the conditions of room temperature (25° C.)/relative humidity 40 to 50% RH.

(Synthesis example: Synthesis of emulsifier S1 for emulsion polymerization)
157.2 parts by mass of N,N-dimethylaminoethyl methacrylate (abbreviation: 2Mabs-MA), 30% aqueous solution of polyoxyethylene polycyclic phenyl ether sulfate ester ammonium salt (manufactured by Nippon Nyukazai Co., Ltd., product name: New Coal ( 920.1 parts by mass of polyoxyethylene polycyclic phenyl ether sulfate ester ammonium salt (abbreviation: 707-SF) obtained by depressurizingly distilling water from (registered trademark) 707-SF (abbreviation: N-707-SF) After the addition, it was allowed to react for 1 hour. After the reaction, 1088.4 parts by mass of the desired emulsifier for emulsion polymerization S1 (abbreviation: emulsifier S1, the compound represented by the chemical formula (6)) was obtained.

(Comparative Synthesis Example 1: Synthesis of emulsifier S2 for emulsion polymerization)
In the same manner as in Synthesis Example 1, except that 517.4 parts by mass of polyoxyethylene tridecyl ether sulfate ester ammonium salt (abbreviation: 1305-SF) synthesized by a conventionally known method was used instead of 707-SF. 657.6 parts by mass of the desired emulsifier for emulsion polymerization S2 (abbreviation: emulsifier S2) was obtained.

(Comparative Synthesis Example 2: Synthesis of emulsifier S3 for emulsion polymerization)
In the same manner as in Synthesis Example, except that 1170.0 parts by mass of polyoxyethylene alkyl ether sulfate ester ammonium salt (abbreviation: 2320-SF) synthesized by a conventionally known method was used instead of 707-SF. 1310.2 parts by mass of emulsifier S3 for emulsion polymerization (abbreviation: emulsifier S3) was obtained.

(Example 1)
Composition A (methyl methacrylate (48)/n-butyl methacrylate (20)/2-ethylhexyl acrylate (30)/acrylic acid (2)/α-methylstyrene dimer (0.2)) + emulsifier S1
130 parts by mass of ion-exchanged water and 0.2 parts by mass of emulsifier S1 were added to a flask equipped with a stirrer, a reflux condenser, a temperature controller, a dropping pump and a nitrogen inlet tube, and the reaction vessel was heated under a nitrogen stream.

When the temperature inside the reaction vessel reached 85° C., 3 parts by mass of a 2% by mass ammonium persulfate aqueous solution was added, and after mixing for 5 minutes, the monomer mixture 1 blended as shown in Table 1 was added dropwise over 90 minutes. . The temperature in the reaction vessel was kept at 85° C. during the dropwise addition. After completion of dropping, the mixture was aged at 85° C. for 90 minutes.

Next, monomer mixture 2 formulated as shown in Table 1 was added dropwise over 90 minutes. The temperature in the reaction vessel was kept at 85° C. during the dropwise addition. After completion of dropping, the mixture was aged at 85° C. for 90 minutes. After cooling to room temperature, 25% aqueous ammonia was added to adjust the pH to 8.5 to obtain polymer emulsion E1.

(Example 2)
Composition B (methyl methacrylate (35)/cyclohexyl methacrylate (31)/n-butyl methacrylate (12)/2-ethylhexyl acrylate (20)/acrylic acid (1)/methyl acrylate (1)/ α-methylstyrene dimer (0.2)) + emulsifier S1
130 parts by mass of ion-exchanged water and 0.2 parts by mass of emulsifier S1 were added to a flask equipped with a stirrer, a reflux condenser, a temperature controller, a dropping pump and a nitrogen inlet tube, and the reaction vessel was heated under a nitrogen stream.

When the temperature inside the reaction vessel reached 85° C., 3 parts by mass of a 2% by mass ammonium persulfate aqueous solution was added, and after mixing for 5 minutes, the monomer mixture 3 blended as shown in Table 2 was added dropwise over 90 minutes. . The temperature in the reaction vessel was kept at 85° C. during the dropwise addition. After completion of dropping, the mixture was aged at 85° C. for 90 minutes.

Next, monomer mixture 4 formulated as shown in Table 2 was added dropwise over 90 minutes. The temperature in the reaction vessel was kept at 85° C. during the dropwise addition. After completion of dropping, the mixture was aged at 85° C. for 90 minutes. After cooling to room temperature, 25% aqueous ammonia was added to adjust the pH to 8.5 to obtain a polymer emulsion E2.

(Comparative example 1)
Composition A + emulsifier for emulsion polymerization S4
Polymerization was carried out in the same manner as in Example 1, except that instead of emulsifier S1, emulsifier S4 for emulsion polymerization (manufactured by ADEKA Corporation, trade name: Adekari Soap (registered trademark) SR-10, abbreviation: emulsifier S4) was used. A coalesced emulsion E3 was obtained.

(Comparative example 2)
Composition B + emulsifier for emulsion polymerization S4
Polymer emulsion E4 was obtained in the same manner as in Example 2, except that emulsifier S4 (manufactured by ADEKA Co., Ltd., trade name: Adekari Soap (registered trademark) SR-10) was used instead of emulsifier S1.

(Comparative Example 3)
Composition A + emulsifier S5 for emulsion polymerization
In the same manner as in Example 1, except that an emulsifier for emulsion polymerization S5 (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon (registered trademark) KH-10, abbreviation: emulsifier S5) was used instead of emulsifier S1. A polymer emulsion E5 was obtained.

(Comparative Example 4)
Composition B + emulsifier S5 for emulsion polymerization
A polymer emulsion E6 was obtained in the same manner as in Example 2, except that emulsifier S5 (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon (registered trademark) KH-10) was used instead of emulsifier S1.

(Comparative Example 5)
Composition A + emulsifier for emulsion polymerization S2
Polymer emulsion E7 was obtained in the same manner as in Example 1, except that emulsifier S2 (compound obtained in Comparative Synthesis Example 1) was used instead of emulsifier S1.

(Comparative Example 6)
Composition B + emulsifier S2 for emulsion polymerization
Polymer emulsion E8 was obtained in the same manner as in Example 2, except that emulsifier S2 (the compound obtained in Comparative Synthesis Example 1) was used instead of emulsifier S1.

(Comparative Example 7)
Composition A + emulsifier S3 for emulsion polymerization
A polymer emulsion E9 was obtained in the same manner as in Example 1, except that emulsifier S3 (compound obtained in Comparative Synthesis Example 2) was used instead of emulsifier S1.

(Comparative Example 8)
Composition B + emulsifier S3 for emulsion polymerization
Polymer emulsion E10 was obtained in the same manner as in Example 2, except that emulsifier S3 (compound obtained in Comparative Synthesis Example 2) was used instead of emulsifier S1.

(Freeze-thaw stability evaluation)
The freeze-thaw stability of the polymer emulsions obtained in Examples 1 and 2 and Comparative Examples 1-8 was evaluated. Specifically, 100 g of each polymer emulsion was placed in a translucent lidded resin container of 100 ml, sealed, and allowed to stand in a constant temperature bath at -10°C for 16 hours, and then at room temperature for 8 hours. Observed the appearance. This was performed for 5 cycles.

In addition, as an evaluation criterion, if it did not freeze even after 5 cycles, or if it became liquid after standing at room temperature for 8 hours even if it was frozen, it was rated as ◯. If it does not return to a liquid state even after being placed, it is marked as x. The results are summarized in Table 3.

(Adhesion evaluation)
The polymer emulsions obtained in Example 1 and Comparative Examples 1, 3, 5 and 7 were evaluated for adhesion. A specific evaluation method is as follows.

For 100 parts by mass of the polymer emulsions obtained in Example 1 and Comparative Examples 1, 3, 5, and 7, 5 parts by mass of a film forming aid (mixture of ethylene glycol monobutyl ether and texanol at a mass ratio of 1:1). Each of the mixtures was applied to a glass substrate to a film thickness of 75 μm. Then, it was dried in a drier at 110° C. for 3 minutes to obtain a test piece having a coating film having a thickness of about 15 μm formed on the glass substrate. Using this test piece, evaluation was performed according to the following procedure, and the results are summarized in Table 4.

(1) After making 11 parallel cuts at intervals of 1 mm to reach the glass substrate, 11 cuts are made in the same manner after changing the direction by 90°;
(2) Adhere cellophane adhesive tape to the incised coating surface so that it adheres to about 50 mm, and rub it with an eraser to adhere the tape to the coating;
(3) After 1 to 2 minutes from adhering to the tape, hold the edge of the tape and keep it perpendicular to the coating surface and peel it off.

Evaluation criteria:
The number of peeled grids out of 100 cut grids is:
0 to 4: ○
5 or more: ×

From the results shown in Tables 3 and 4, by using the freeze-thaw stability improver or adhesion improver of the present invention, extremely excellent freeze-thaw stability of the emulsion and adhesion between the polymer and the substrate are achieved. It can be seen that

Claims (2)

An agent for improving the freeze-thaw stability of a polymer emulsion, containing a compound represented by the following general formula (1):

In general formula (1), Q ⁺ is a primary ammonium ion, a secondary ammonium ion, a tertiary ammonium ion, a quaternary ammonium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, a piperidinium ion, a nitrogen-containing compound cation selected from quinolinium ions, morpholinium ions, and imidazolidinonium ions (ethylene urea) ;
A is a linear or branched alkylene group having 2 to 4 carbon atoms,
m represents the average number of added moles of AO and is a number from 1 to 150,
Y is a single bond or a linear or branched alkylene group having 1 to 5 carbon atoms,
R ₁ is a hydrogen atom or a methyl group,
R ₂ is a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 25 carbon atoms, or a group represented by the following general formula (2);
l is an integer from 1 to 3,

In general formula (2), R ₃ and R ₄ each independently represent a hydrogen atom or a methyl group, and * represents a connecting point. The freeze-thaw stability improver according to claim 1, wherein Q ⁺ is a nitrogen-containing compound cation represented by the following general formula (3).

In general formula (3), R ₅ and R ₆ are each independently a linear or branched alkyl group having 1 to 4 carbon atoms, and R ₇ is a linear or branched alkyl group having 2 to 4 carbon atoms. It is a branched alkylene group, X is an oxygen atom or NH, and _R8 is a hydrogen atom or a methyl group.