JP2002322218A - Acrylic resin emulsion and method for producing the same - Google Patents

Abstract

(57) [Problem] To use an acrylic monomer having an amino group,
Further, it is an object to obtain an acrylic resin emulsion having improved water resistance. An amino-containing acrylic monomer partially or wholly neutralized with an organic acid having a boiling point of 80 to 150 ° C,
And alkyl (meth) acrylate are emulsion-polymerized in the presence of a cationic or nonionic emulsifier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an acrylic resin emulsion having excellent water resistance.

[0002]

2. Description of the Related Art When an emulsion is produced using an acrylic monomer containing an amino group, an acrylic monomer in which the amino group is neutralized with an inorganic acid such as hydrochloric acid may be used.

[0003]

However, when emulsion polymerization is carried out using an acrylic monomer whose amino group has been neutralized with an inorganic salt, the resin component of the obtained emulsion contains
There will be an ionic water-soluble moiety called a quaternary ammonium salt. For this reason, when a film is formed using this emulsion, the resulting film may not have sufficient water resistance.

Accordingly, an object of the present invention is to obtain an acrylic resin emulsion using an acrylic monomer having an amino group and having improved water resistance.

[0005]

According to the present invention, the boiling point is 80 to 80%.
The above-mentioned problem has been solved by emulsion-polymerizing an amino group-containing acrylic monomer and an alkyl (meth) acrylate partially or wholly neutralized with an organic acid at 150 ° C. in the presence of a cationic or nonionic emulsifier. It is.

An acrylic monomer having an amino group has a boiling point of 80.
Since part or all is neutralized and subjected to emulsion polymerization using an organic acid at ~ 150 ° C, the organic acid can be volatilized when the obtained acrylic resin emulsion is dried to form a film. . For this reason, the ionic portion is reduced in the obtained film, and the water resistance can be improved.

[0007]

Embodiments of the present invention will be described below. The acrylic resin emulsion according to the present invention,
An amino group-containing acrylic monomer partially or wholly neutralized with an organic acid and a monomer mainly composed of alkyl (meth) acrylate are emulsion-polymerized in the presence of an emulsifier.

The above-mentioned amino group-containing acrylic monomer is
It refers to (meth) acrylic acid ester or (meth) acrylamide containing an amino group, and includes an aminoalkyl (meth) acrylate monomer and an N-aminoalkyl (meth) acrylamide monomer.

Specific examples of the aminoalkyl (meth) acrylate monomer include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and monomethylaminoethyl ( (Meth) acrylate and the like.

Further, specific examples of the N-aminoalkyl (meth) acrylamide monomer include dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylamide and the like.

The amino group-containing acrylic monomer is partially or entirely neutralized with an organic acid and is subjected to emulsion polymerization. The boiling point of this organic acid is preferably 80 to 150 ° C.
0-120 ° C is preferred. Organic acids with boiling points below 80 ° C. are difficult to obtain, expensive and not economical. On the other hand, when the boiling point is higher than 150 ° C., the volatility at the time of drying is reduced, and the volatilization of the organic acid may be insufficient.

As such an organic acid, an organic carboxylic acid is preferable. Examples of the organic carboxylic acid include formic acid (boiling point 100.8 ° C.), acetic acid (boiling point 117.8 ° C.), propionic acid (boiling point 140.8 ° C.), and the like. At least one of these may be used.

The above-mentioned alkyl (meth) acrylate is
It refers to an alkyl ester of (meth) acrylic acid, and is preferably an alkyl ester of (meth) acrylic acid having 1 to 10 carbon atoms in the alkyl group. Specific examples include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth)
Acrylate, hydroxypropyl (meth) acrylate, β-ethoxyethyl (meth) acrylate, glycidyl (meth) acrylate and the like can be mentioned. by the way,
The alkyl group includes a substituted alkyl group.

In the present invention, (meth) acryl means acryl or methacryl. Also,
The phrase “mainly composed of (meth) acrylate” means that the proportion of alkyl (meth) acrylate in the monomer other than the partially or wholly neutralized amino group-containing acrylic monomer is 以上 or more, preferably Indicates a state of 2/3 or more.

The partially or wholly neutralized amino group-containing acrylic monomer and the partially or wholly neutralized amino group-containing acrylic monomer contained in the monomer mainly composed of alkyl (meth) acrylate Examples of the monomer components other than the alkyl (meth) acrylate include aromatic vinyl compounds such as styrene, unsaturated nitriles such as acrylonitrile, and vinyl esters such as vinyl acetate.

The ratio of the above-mentioned amino group-containing acrylic monomer and the monomer mainly composed of alkyl (meth) acrylate is expressed by weight ratio of amino group-containing acrylic monomer /
Monomers based on alkyl (meth) acrylate = 1
/ 99 to 5/95 is good, and 1.5 / 98.5 to 3.5 /
96.5 is preferred. If it is smaller than 1/99, the stability of the emulsion at the time of polymerization tends to decrease. on the other hand. If it is larger than 5/95, the water resistance of the dried film may decrease.

Emulsion polymerization of a mixture of an amino group-containing acrylic monomer partially or wholly neutralized with the above organic acid and a monomer mainly composed of alkyl (meth) acrylate in the presence of an emulsifier. Gives an acrylic resin emulsion.

As the above-mentioned emulsifier, a cationic or nonionic emulsifier can be used. Examples of the cationic emulsifier include stearylamine hydrochloride, lauryl trimethyl ammonium chloride, trimethyl octadecyl ammonium chloride and the like.

Examples of the nonionic emulsifier include polyethylene oxide nonionic surfactants, such as polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene oxypropylene block polymer, and polyethylene glycol fatty acid. Esters and polyoxyethylene sorbitan fatty acid esters.

Examples of the polyoxyethylene alkyl ether include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene nonyl ether.
As polyoxyethylene alkyl allyl ether,
And polyoxyethylene nonylphenyl ether.

Examples of polyethylene glycol fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate,
And polyoxyethylene sorbitan monooleate.

In the emulsion polymerization method, at least a part of the above-mentioned amino group-containing acrylic monomer is neutralized by adding 0.2 equivalent or more of an organic acid. Depending on the use of the emulsion, more than one equivalent of organic acid may be added. A preferable neutralization ratio is 0.5 to 1 equivalent.

Next, an amino group-containing acrylic monomer partially or wholly neutralized and the above-mentioned monomer mainly composed of alkyl (meth) acrylate are mixed at a predetermined ratio, and a cationic or nonionic emulsifier is added. Emulsion polymerization in the presence of an agent. Thereby, an acrylic resin emulsion can be manufactured. As a method for charging each monomer, any method such as a batch charging method and a dropping method can be adopted.

As the above-mentioned polymerization initiator, a general nonionic or cationic polymerization initiator can be used. For example, a known cationic catalyst such as 2,2'-azobis (2-amidinopropane) is used in aqueous solution. Sex salts such as hydrochloride can be used. Also, if necessary, various alcohols,
Chain transfer agents such as aldehydes and mercaptans can be used within a range that does not cause various adverse effects.

The resulting acrylic resin emulsion is applied and dried to form a film, and at the same time, the organic acid is volatilized. The film thus obtained is 23
The water absorption of the above film after immersion in water at ℃ for 7 days is 18%
Or less, preferably 13% or less. Further, the swelling ratio of the film after immersion for 7 days is preferably 10% or less.
% Or less is preferable.

If the water absorption is more than 18%, the water resistance of the film is inferior, which may cause a problem in use. If the coefficient of expansion is greater than 10%, the film may bulge or peel off during immersion in water.

[0027]

The present invention will be described below in more detail with reference to examples. Example 1 In a separable flask equipped with a stirring blade, a reflux condenser, a thermometer and a dropping funnel, 52 parts by weight of ion-exchanged water and trade name Emulgen A-60 (Kao Corporation) as a nonionic surfactant Was added and dissolved.

Next, the temperature of the surfactant solution was raised to 68 ° C., and 2.5 parts by weight of dimethylaminoethyl methacrylate (hereinafter abbreviated as “DMA”) was added as an amino group-containing acrylic monomer. Thereafter, 1.25 parts by weight of 95% by weight formic acid diluted with ion-exchanged water to a formic acid concentration of 35% by weight (about 0.6 equivalent to the amino group-containing monomer) was added and mixed for 10 minutes. After partially neutralizing the amino group-containing acrylic monomer, 0.55 parts by weight of a 15% by weight aqueous solution of 2,2′-azobis (2-amidinopropane) dihydrochloride was added. Then, 28 parts by weight of methyl methacrylate (hereinafter abbreviated as “MMA”),
2-ethylhexyl acrylate (hereinafter, “2EHA”)
Abbreviated as ) A monomer obtained by mixing 63.5 parts by weight and 6 parts by weight of butyl acrylate (hereinafter, abbreviated as “BA”) was continuously dropped into the reaction vessel with a dropping funnel. Keep the temperature inside the reaction vessel at 73 ± 2 ° C
The dripping was completed in time.

After completion of the dropwise addition of the monomer, 0.41 part by weight of a 10% by weight aqueous solution of 2,2′-azobis (2-amidinopropane) dihydrochloride was added, and the temperature in the reaction vessel was set to 80 ± 1.
C. and a ripening reaction was performed for 3 hours. After the reaction, add 4
After cooling to 0 ° C., an acrylic resin emulsion was obtained. The resulting acrylic resin emulsion had a nonvolatile content of 60.5.
%, A viscosity of 1350 mPa · s and a pH of 6.7. Using the obtained acrylic resin emulsion, a strong elongation test and a coating water immersion test were performed according to the following methods. Table 1 shows the results.

[Strength elongation test] The above acrylic resin emulsion was dried on a Teflon (registered trademark) plate to a dry film thickness of about 1 mm.
And dried at room temperature for at least one week to obtain a test film. The obtained test film was punched out with a dumbbell No. 2 and pulled at a tensile speed of 200 mm / min using a universal tensile tester to measure the strong elongation. In particular,
The strength at the time of breaking was defined as tensile strength, and the elongation until that time was defined as elongation.

[Coating water immersion test]
The film was cut into m-squares, and the film change after immersion in 23 ° C. water for 2, 4, 7 days was measured. From the change in film weight, the water absorption
The swelling rate was measured from the change in the length of the test film side, and the dissolution rate was measured from the change in the test film weight after re-drying.

(Example 2) In a separable flask equipped with a stirring blade, a reflux condenser, a thermometer and a dropping funnel, 35 parts by weight of ion-exchanged water and Nonipol 200 (trade name, Sanyo Chemical Industries, Ltd.) were used as nonionic surfactants. Co., Ltd.)
One part by weight was added and dissolved.

Next, the temperature of this surfactant solution was raised to 58 ° C., and as an amino group-containing acrylic monomer, DM
After adding 2.65 parts by weight of A, 2.23 parts by weight of 95% by weight of formic acid diluted with ion-exchanged water to a formic acid concentration of 35% by weight was added (based on the amino group-containing monomer,
(About 1.0 equivalent) and mixed for 10 minutes to neutralize the amino group-containing acrylic monomer, and then add 2,2′-azobis (2
1.53 parts by weight of a 15% by weight aqueous solution of (amidinopropane) dihydrochloride were added. Then, 38 parts by weight of MMA,
2EHA 59.15 parts by weight, DMA 0.2 parts by weight, trade name Emulgen A- as a nonionic surfactant component
3.5 (by Kao Corporation) 95% by weight formic acid 0.0 as a neutralizing agent for an amino group-containing acrylic monomer
65 parts by weight (approx.
(Equivalent) and 44.3 parts by weight of ion-exchanged water were continuously dropped into the reaction vessel with a dropping funnel. The temperature in the reaction vessel was kept at 60 ± 2 ° C. during the dropping of the monomer emulsion, and the dropping was completed in 4 hours.

After the completion of the dropwise addition of the monomer emulsion,
2′-azobis (2-amidinopropane) dihydrochloride 1
1.05 parts by weight of a 0% by weight aqueous solution was added, and the aging reaction was carried out at a temperature of 80 ± 1 ° C. for 3 hours. After the reaction, the reaction solution was cooled to 40 ° C. to obtain an acrylic resin emulsion. The obtained acrylic resin emulsion had a nonvolatile content of 55.0%, a viscosity of 2950 mPa · s, and a pH of 6.0.
It was 0. Using the obtained acrylic resin emulsion, a strong elongation test and a coating water immersion test were performed according to the methods described above. Table 1 shows the results.

Example 3 In a separable flask equipped with a stirring blade, a reflux condenser, a thermometer, and a dropping funnel, 43 parts by weight of ion-exchanged water and Nonipol 200 (trade name, Sanyo Chemical Industries, Ltd.) as a nonionic surfactant were used. Co., Ltd.)
One part by weight was added and dissolved.

Next, the temperature of this surfactant solution was raised to 68 ° C., and as an amino group-containing acrylic monomer, DM
After adding 2.65 parts by weight of A, 2.23 parts by weight of 95% by weight of formic acid diluted with ion-exchanged water to a formic acid concentration of 35% by weight was added (based on the amino group-containing monomer,
(About 1.0 equivalent) and mixed for 10 minutes to neutralize the amino group-containing acrylic monomer, and then add 2,2′-azobis (2
1.53 parts by weight of a 15% by weight aqueous solution of (amidinopropane) dihydrochloride were added. Then, 16.6 parts by weight of MMA, 55.55 parts by weight of 2EHA, 25 parts by weight of styrene,
DMA 0.2 part by weight, trade name Emulgen A-60 (manufactured by Kao Corporation) as a nonionic surfactant component
3.5 parts by weight, 95% by weight as a neutralizing agent for the amino group-containing acrylic monomer 0.065 parts by weight of formic acid (about 1.0 equivalent to the amino group-containing monomer), and 44.3 parts by weight of ion-exchanged water The monomer emulsion containing the mixed parts was continuously dropped into the reaction vessel with a dropping funnel. The temperature in the reaction vessel during dropping of the monomer emulsion was kept at 70 ± 2 ° C., and the dropping was completed in 4 hours.

After the completion of the dropping of the monomer emulsion,
2′-azobis (2-amidinopropane) dihydrochloride 1
1.05 parts by weight of a 0% by weight aqueous solution was added, and the aging reaction was carried out at a temperature of 80 ± 1 ° C. for 3 hours. After the reaction, the reaction solution was cooled to 40 ° C. to obtain an acrylic resin emulsion. The obtained acrylic resin emulsion had a nonvolatile content of 53.0%, a viscosity of 4100 mPa · s, and a pH of 4.0.
It was 2. Using the obtained acrylic resin emulsion, a strong elongation test and a coating water immersion test were performed according to the methods described above. Table 1 shows the results.

Comparative Example 1 An acrylic resin emulsion was obtained in the same manner as in Example 1 except that hydrochloric acid was used in place of formic acid in corresponding amounts. The obtained acrylic resin emulsion had a nonvolatile content of 60.6% and a viscosity of 3100 mPa ·
s, pH 6.5. Using the obtained acrylic resin emulsion, a strong elongation test and a coating water immersion test were performed according to the methods described above. Table 1 shows the results.

Comparative Example 2 An acrylic resin emulsion was obtained in the same manner as in Example 2, except that hydrochloric acid was used in place of formic acid in corresponding amounts. The obtained acrylic resin emulsion had a nonvolatile content of 55.2% and a viscosity of 4500 mPa ·
s, pH 6.3. Using the obtained acrylic resin emulsion, a strong elongation test and a coating water immersion test were performed according to the methods described above. Table 1 shows the results.

[0040]

[Table 1]

[Results] The films obtained from the acrylic resin emulsions of Examples 1 to 3 had a water absorption and a swelling ratio of about half those of Comparative Examples 1 and 2, and the elution rate was low. For this reason, it became clear that the water resistance was improved.

[0042]

According to the present invention, the emulsion polymerization is carried out using an amino group-containing acrylic monomer partially or wholly neutralized with an organic acid having a predetermined boiling point. When obtaining a film, the organic acid can be volatilized. For this reason, the ionic portion is reduced in the obtained film, and the water resistance can be improved.

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Claims (6)

[Claims] 1. An amino group-containing acrylic monomer partially or wholly neutralized with an organic acid having a boiling point of 80 to 150 ° C.,
And an acrylic resin emulsion obtained by emulsion polymerization of a monomer mainly containing an alkyl (meth) acrylate in the presence of a cationic or nonionic emulsifier. 2. The acrylic resin emulsion according to claim 1, wherein the organic acid is an organic carboxylic acid. 3. The acrylic resin emulsion according to claim 2, wherein the organic carboxylic acid is at least one selected from formic acid, acetic acid, and propionic acid. 4. The method according to claim 1, wherein the ratio of the amino group-containing acrylic monomer to the monomer mainly composed of alkyl (meth) acrylate is from 1/99 to 5/95 (weight ratio). The acrylic resin emulsion according to any one of the above. 5. An organic acid having a boiling point of 80 to 150 ° C.
A method for producing an acrylic resin emulsion in which a part or all of an amino group-containing acrylic monomer is neutralized, and this is emulsion-polymerized with a monomer mainly composed of an alkyl (meth) acrylate in the presence of a cationic or nonionic emulsifier. . 6. An acrylic resin having a water absorption of 18% or less and a swelling of 10% or less after immersing the film comprising the acrylic resin emulsion according to claim 1 in water at 23 ° C. for 7 days. Resin film.