JPH0657782B2 - Method for producing aqueous resin dispersion for sealer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing an aqueous resin dispersion for a sealer.

More specifically, it relates to a method for producing an aqueous resin dispersion for a sealer which, when applied to a porous substrate, provides a film excellent in adhesion, water resistance, durability and smoothness by well impregnating the substrate. .

(Problems to be solved by the prior art and the present invention) Conventionally, as a resin used for a sealer of an inorganic porous substrate, a relatively low molecular weight moisture-curable urethane, a solvent type resin, etc. have been used. The former is its toxicity, and the latter is problematic in terms of fire risk and environmental pollution due to the use of organic solvents, and there is a strong demand for water solubilization. Various water-based sealers containing water-soluble resin or water-dispersible resin as the main component have been investigated, but those containing water-soluble resin as the main component have water resistance, and water-dispersible resin as the main component. Those that do not have long-term durability because of poor impregnation and adhesion to the substrate. Further, a method of mixing and using a water-soluble resin and a water-dispersible resin has been investigated. For example, a method of blending 5 to 80% of a water-soluble resin with an acrylic emulsion (Japanese Patent Laid-Open No. 61-141769) and a specific weight ratio. A method of blending polyvinyl alcohol with a coalesced aqueous emulsion (Japanese Patent Laid-Open No. Sho 5
3-970818) and the like have been proposed, but none of them has been found to satisfy the performances such as impregnation property and water resistance / durability with respect to the inorganic porous substrate. On the other hand, although the method using an epoxy emulsion is excellent in impregnating ability for the substrate, it uses a curing agent, so it becomes a two-part solution, and handling is complicated, and there are problems of pot life and restrictions on the time for topcoating. Has many problems on. In addition, since a large amount of emulsifier is required when emulsifying an epoxy resin in water, a decrease in water resistance cannot be avoided. From the above, it is the current situation that an aqueous resin sealer that is easy to handle and has sufficient performance has not been obtained.

(Technical Means for Solving Problems) The present invention has the above-mentioned problems, namely, toxicity of a sealer mainly composed of moisture-curable urethane or solvent-based resin, risk of fire, environmental pollution, etc. It is a solution to problems such as insufficient water resistance, insufficient impregnation, insufficient adhesion, and insufficient durability of water-based sealers.

As a result of intensive studies by the present inventors, an aqueous resin dispersion obtained by mixing an emulsion obtained by emulsifying a specific hydrophobic epoxy resin with a specific polyvinyl alcohol in an aqueous resin dispersion, The inventors have found that the conventional water-soluble resins and water-dispersible resins have no drawbacks at all, and have no fear of toxicity or environmental pollution, and have completed the present invention.

That is, the present invention is a sealer characterized by adding a hydrophobic epoxy resin emulsified with polyvinyl alcohol having a saponification degree of 80 mol% or more to an aqueous resin dispersion obtained by emulsion-polymerizing a vinyl-based polymerizable monomer. The present invention relates to a method for producing an aqueous resin dispersion for use.

The aqueous resin dispersion in the present invention is not particularly limited as long as it is conventionally known, but an aqueous resin dispersion of a vinyl polymer is preferable, for example, an acrylic resin emulsion,
Examples thereof include styrene-acrylic resin emulsion, ethylene-vinyl acetate emulsion, acrylic-styrene-vinyl acetate emulsion, styrene-vinyl acetate emulsion, vinylidene chloride emulsion, vinyl chloride emulsion and the like. Among these, acrylic resin emulsion and styrene-acrylic resin emulsion are particularly preferable. Such an aqueous resin dispersion is obtained by emulsion-polymerizing a vinyl-based polymerizable monomer by a known method, and the vinyl-based polymerizable monomer that can be used is not particularly limited, and examples thereof include methyl (meth). ) Acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
(Meth) acrylates such as 2-ethylhexyl (meth) acrylate and cyclohexyl (meth) acrylate; aromatic unsaturated monomers such as styrene, α-methylstyrene, α-chlorostyrene and vinyltoluene; vinyl fluoride, chloride Vinyl halides such as vinyl and vinylidene chloride; unsaturated cyan compounds such as (meth) acrylonitrile; vinyl esters such as vinyl acetate and vinyl propionate; hydroxy such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate Group-containing unsaturated monomers; (meth) acrylamide, N-
Unsaturated acid amides such as methylol (meth) acrylamide or its derivatives; dimethylaminoethyl (meth)
Amino group-containing unsaturated monomers such as acrylates; Polyfunctional unsaturated monomers such as divinylbenzene, ethylene glycol di (meth) acrylate; Glycidyl group-containing unsaturated groups such as glycidyl (meth) acrylate and allyl glycidyl ether Monomers; (meth) acrylic acid,
Unsaturated carboxylic acids such as crotonic acid, itaconic acid, fumaric acid, maleic acid, monomethyl fumarate and monoethyl maleate or derivatives thereof may be mentioned, and one or more of these may be used. .

The aqueous resin dispersion in the present invention may be emulsion-polymerized with a polymerization initiator in the presence or absence of an emulsifier for the vinyl-based polymerizable monomer, and examples of the polymerization initiator include ammonium persulfate and persulfate. Known water-soluble or oil-soluble initiators such as potassium, hydrogen peroxide and benzoyl peroxide can be used. At this time, a redox initiator may be used by using sodium bisulfite, L-ascorbic acid or the like as a reducing agent. Examples of emulsifiers used as needed include anionic activators such as sodium lauryl sulfate and nonionic activators such as polyoxyethylene alkyl ether. Further, a chain transfer agent such as lauryl mercaptan may be used for the purpose of controlling the molecular weight during the polymerization. Further, during emulsion polymerization, the composition of the polymerizable monomer or the like may be changed at each stage to carry out multistage emulsion polymerization.

The polyvinyl alcohol used in the present invention has a saponification degree of 80 mol% or higher, preferably 87 mol% or higher. When polyvinyl alcohol having a saponification degree of less than 80 mol% is used, the crystallinity is lowered and the hydrophilicity is increased, and the water resistance of the aqueous resin dispersion obtained by the production method of the present invention is increased when it is used as a sealer. It is not preferable because it decreases.
The amount of polyvinyl alcohol used in the present invention is not particularly limited, but when the aqueous resin dispersion for a sealer in the present invention is used for coating a porous substrate, it is water-based in terms of adhesion and water resistance to the substrate. The solid content ratio is preferably 1 to 40 parts by weight, and more preferably 5 to 35 parts by weight, based on 100 parts by weight of the resin dispersion. Further, the degree of polymerization of polyvinyl alcohol in the present invention is preferably in the range of 200 to 2600, more preferably in the range of 500 to 2400 in terms of water resistance and viscosity of the finally obtained aqueous resin dispersion for sealer. Is. As the polyvinyl alcohol used in the present invention, a polymer in which a part of the vinyl alcohol unit is replaced by another vinyl monomer unit or a part of the hydrogen of the hydroxyl group present in the polyvinyl alcohol is replaced by another compound. It may be a polymer, for example, a polymer partially butyralized.

The hydrophobic epoxy resin in the present invention is not particularly limited as long as it is hydrophobic, but any conventionally known one may be used.
For example, bisphenol A type epoxy resin, cycloaliphatic epoxy resin, novolac type epoxy resin, resorcin type epoxy resin, bisphenol F type epoxy resin, halogenated bisphenol type epoxy resin, tetrahydroxyphenylethane type epoxy resin, glycerin triether type epoxy resin. , Polyolefin type epoxy resin,
Examples thereof include epoxidized soybean oil, and among these, bisphenol A type epoxy resin and novolac type epoxy resin are particularly preferable. These epoxy resins may be epoxy resins in which a part of epoxy groups are replaced with other substituents, and may be monofunctional or polyfunctional. The hydrophobic epoxy resin used in the present invention has an epoxy equivalent of 150 to 3500, preferably an epoxy equivalent of 180 to 3000. The amount of the epoxy resin used in the present invention is not particularly limited,
When the aqueous resin dispersion for a sealer obtained by the production method of the present invention is used for coating a porous substrate, 100 parts by weight of the aqueous resin dispersion is adhered to the substrate, water resistance and stability during storage. On the other hand, the solid content ratio is preferably in the range of 1 to 40 parts by weight, more preferably 5 to 35 parts by weight.

In the production method of the present invention, the epoxy resin is emulsified with polyvinyl alcohol, and the emulsifying device used at this time is not particularly limited, but an emulsifier commonly used for improving the emulsion stability of the epoxy resin may be used in combination. .
However, the amount of the emulsifier used is preferably 5 parts by weight or less in terms of solid content relative to 100 parts by weight of the epoxy resin, and if added in excess of this amount, the water resistance of the aqueous resin dispersion obtained will be reduced.
Further, the solid epoxy resin is previously dissolved in a solvent to facilitate emulsification. Examples of the solvent used at this time include ketones, esters, ethers and alcohols, but are not particularly limited.

The aqueous resin dispersion for a sealer obtained in the present invention is used as it is as a sealer for an inorganic porous substrate, but if necessary, a film forming aid, a hydrophilic resin, a pigment, a filler, a toner,
You may mix and use additives, such as a dispersing agent and a wetting agent. However, the amount of the pigment, the filler, and the toner used is 300 parts by weight or less per 100 parts by weight of the aqueous resin dispersion (calculated as nonvolatile content) so as not to impair the characteristics of the aqueous resin dispersion obtained by the production method of the present invention. Preferably.

(Effect of the invention) The aqueous resin dispersion obtained by the production method of the present invention is obtained by adding a hydrophobic epoxy resin emulsified with polyvinyl alcohol to the aqueous resin dispersion, so that the aqueous resin dispersion and polyvinyl alcohol are simply added. Compared to the mixture, it has excellent adhesion to substrates and water resistance such as hot water resistance, durability such as frost damage resistance, lifting resistance at the time of coating top coat, interlayer with top coat Adhesion is also improved. Further, as compared with the epoxy emulsion, since it can be handled as a single liquid, the complexity of handling and the problem of pot life are eliminated, and there is also no limitation on the coating interval when performing topcoating. Therefore, the aqueous resin dispersion according to the present invention can be suitably used as a sealer for substrates such as mortar, concrete, and calcium silicate plate.

(Examples) The present invention is described in detail below with reference to examples, but the present invention is not limited to the following examples. The parts in the examples are by weight unless otherwise specified.

Example 1 1 equipped with a stirrer, reflux condenser, dropping funnel, thermometer
After deionized water (500 parts) and sodium lauryl sulfate (8 parts) were charged in the separable flask (2), the temperature was raised to 70 ° C. with stirring while blowing nitrogen gas. Then, a polymerizable monomer mixture consisting of 160 parts of methyl methacrylate, 80 parts of styrene, 152 parts of butyl acrylate and 8 parts of methacrylic acid was uniformly added dropwise over 2 hours. During this period, 10 parts of a 10% ammonium persulfate aqueous solution was uniformly added dropwise over 2 hours. After aging for 1 hour, it was cooled and 6.3 parts of 25% ammonia water was added. The aqueous resin dispersion (1) thus obtained had a nonvolatile content of 43.5
%, PH 9.0, viscosity 150 cps (B type viscometer, No. 2 rotor, 30 rpm, 25 ° C.), minimum film forming temperature 35 ° C. After charging 60 parts of a 10% aqueous solution of Kuraray Poval PVA-171 (polyvinyl alcohol manufactured by Kuraray Co., Ltd .: polymerization degree 1700, saponification degree 98 to 99 mol%) into a separable flask, ADEKA RESIN EP under stirring
-4100 (Bisphenol type epoxy resin manufactured by Asahi Denka Co., Ltd .: epoxy equivalent 180 to 200, molecular weight about 360)
Of 6 parts, and emulsification was performed at a stirring speed of 200 rpm for 10 minutes, and then 200 parts of the aqueous resin dispersion (1) was added and further mixed for 10 minutes to prepare an aqueous resin dispersion for sealer (1). Got The resulting aqueous resin dispersion for sealer (1) had a nonvolatile content of 37.2%, pH 8.5, and a viscosity of 1000 cp.
s (B type viscometer, No.3 rotor, 30 rpm, 25
C), and the minimum film formation temperature of 10 ° C.

The obtained aqueous resin dispersion for sealer (1) was coated on the inorganic porous substrate shown in Table 2 in a solid content of 20 g / m ² and 1
After drying in a hot air dryer at 20 ° C. for 10 minutes, the adhesion of the coating film to the substrate, hot water resistance and frost damage resistance were examined.
Furthermore, on the coating film of the aqueous resin dispersion for sealer (1),
The top-coat paint obtained with the paint composition shown in the table has a solid content of 4
After coating with 0 g / m ² and drying with a hot air dryer at 120 ° C. for 10 minutes, the top coating characteristics were examined. The results are as shown in Table 2. Similar tests were performed on the aqueous resin dispersions for sealers obtained in the following Examples and Comparative Examples.

In addition, the obtained aqueous resin dispersion for sealer (1) was heated to 50 ° C.
It was stored for 30 days at room temperature, and its storage stability was examined. Similar tests were conducted on the aqueous resin dispersions for sealers obtained in the following Examples and Comparative Examples, and the results are shown in Table 3.

Example 2 After the same separable flask as used in Example 1 was charged with 350 parts of deionized water, the temperature was raised to 60 ° C. with stirring while blowing nitrogen gas. After that, 200 parts of methyl methacrylate and 1 of cyclohexyl methacrylate
Emulgen 950 (manufactured by Kao Corporation) in a polymerizable monomer mixture consisting of 00 parts, 90 parts of 2-ethylhexyl acrylate, 4 parts of glycidyl methacrylate and 6 parts of acrylic acid.
10 parts of polyoxyethylene nonylphenyl ether,
Rebenol WZ (25% aqueous solution of sodium polyoxyethylene nonylphenyl ether sulfate manufactured by Kao Corporation) 1
The pre-emulsion mixture obtained by adding 6 parts and 120 parts of deionized water was uniformly added dropwise over 3 hours. During this period, 60 parts of a 2% aqueous solution of potassium persulfate and 12 parts of a 5% aqueous solution of sodium bisulfite were added to the flask every 10 minutes until the end of the dropping of the pre-emulsion mixture.
After completion of dropping, the mixture was aged for 1 hour and cooled, and then 25
5.7 parts of% aqueous ammonia was added. The thus-obtained aqueous resin dispersion (2) showed non-volatile content of 42.5%, pH of 9.1, viscosity of 2400 cps, and a minimum film forming temperature of 65 ° C. 50 Epicoat 1007 (bisphenol A type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd .: epoxy equivalent 1750 to 2150, molecular weight about 2900) was placed in the flask.
After adding 50 parts, add 50 parts of butyl cellosolve and add 120 parts.
After the temperature was raised to 0 ° C. and the mixture was dissolved under stirring, the mixture was cooled, and 6 parts of Adecanol NK511 (Epoxy resin emulsifier manufactured by Asahi Denka Co., Ltd .: 30% aqueous solution) was added and well mixed with stirring. After that, the stirring speed in the flask is 400 rpm.
Then, 350 parts of a 10% aqueous solution of Kuraray Poval PVA-205 (manufactured by Kuraray Co., Ltd .: polymerization degree 500, saponification degree 87 to 89 mol%) was added to a separable flask and emulsified for 30 minutes. Then, 200 parts of the aqueous resin dispersion (2) was added, stirring was continued for 10 minutes, and then taken out to obtain an aqueous resin dispersion (2) for a sealer. The obtained aqueous resin dispersion for sealer (2) had a nonvolatile content of 26.1%, a pH of 8.1, a viscosity of 1800 cps (B type viscometer, No. 3 rotor, 30 rpm, 25 ° C.), and a minimum film formation temperature of 0 ° C. or less. Numerical values are shown.

Example 3 In a separable flask, 40 parts of butyl cellosolve and 40 parts of Epicoat 154 (Novolak type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd .: epoxy equivalent 176 to 181) were used.
Part, ADEKA RESIN EPU-4-75X (Usahi Denka Co., Ltd. urethane-modified epoxy resin: epoxy equivalent 750-85)
80 parts of 0, xylene solution, 75%) were charged, and the temperature was raised to 100 ° C. with stirring to dissolve the epoxy resin over 30 minutes. Next, put Kuraray Poval P in the glass container of 1.
VA-224E (polyvinyl alcohol manufactured by Kuraray Co., Ltd .: degree of polymerization 2400, degree of saponification 87 to 89 mol%) 10
% 300% aqueous solution was charged, a homomixer was installed, stirring was started at 6000 rpm, and the epoxy resin dissolved above was emulsified. Then, Example 1
322 parts of the aqueous resin dispersion for sealer (1) used in (3) was added and further mixed for 10 minutes. The resulting aqueous resin dispersion for sealer (3) had a nonvolatile content of 29.3% and a pH of 8.
7. Viscosity 2500cps (B type viscometer, No.3 rotor,
30 rpm, 25 ° C.), and the minimum film formation temperature was 0 ° C. or less.

Comparative Example 1 20 parts of the aqueous resin dispersion (1) obtained in Example 1 was mixed with 150 parts of a 10% aqueous solution of Kuraray Poval PVA-117 to obtain a comparative aqueous resin dispersion for sealer (1). It was This comparative aqueous resin dispersion for sealer (1) had a nonvolatile content of 29.0%, a pH of 8.9, a viscosity of 2200 cps (B type viscometer) and a minimum film forming temperature of 0 ° C. or less.

Comparative Example 2 After charging 80 parts of a 10% aqueous solution of Kuraray Poval PVA-117 in a separable flask, the stirring speed was 200 r.
After adjusting to pm, 60 parts of ADEKA RESIN EP-4100 and 20 parts of NK-511 as an emulsifier were added, and emulsification was performed for 10 minutes. Then, 150 parts of the aqueous resin dispersion (1) used in Example 1 was added and mixed for 10 minutes to obtain a comparative aqueous resin dispersion for a sealer (2).
The comparative water-based resin dispersion for sealer (2) obtained had a non-volatile content of 44.9%, a pH of 8.2, a viscosity of 1400 cps, and a minimum film-forming temperature of 12 ° C.

Comparative Example 3 After charging 50 parts of Epicoat 1007 into a flask,
Add 50 parts of butyl cellosolve, raise the temperature to 120 ° C., dissolve under stirring, then cool and add adecanol NK
6 parts of -511 was added and dissolved. Then, a homomixer was installed, the stirring speed was adjusted to 6000 rpm, 200 parts of the aqueous resin dispersion (2) obtained in Example 2 was added, and it was attempted to emulsify over 30 minutes. I couldn't get anything.

Comparative Example 4 After charging 100 parts of deionized water in a flask, the stirring speed was adjusted to 400 rpm, and ADEKA RESIN EP-410 was used.
0 and 40 parts of ADEKANOL NK-511 were added, and the mixture was emulsified for 30 minutes. Then, Example 1
200 parts of the aqueous resin dispersion (1) obtained in
Mixing was performed for 10 minutes to obtain a comparative aqueous resin dispersion for sealer (4). The comparative water-based resin dispersion for sealer (4) obtained had a non-volatile content of 37.4%, a pH of 8.3, a viscosity of 800 cps (B-type viscometer) and a minimum film-forming temperature of 27 ° C.

Comparative Example 5 Denacol EX-832 (Nagase Sangyo Co., Ltd.) was placed in a flask.
25 parts of water-soluble epoxy resin (epoxy equivalent: 280) was added, 12.1 parts of 25% ammonia water was added, and further 350 parts of a 10% aqueous solution of Kuraray Poval PVA-205 was added and dissolved with stirring. Then, 200 parts of the aqueous resin dispersion (2) used in Example 2 was added, and stirring was continued for 10 minutes to obtain an aqueous resin dispersion for sealer (5) for comparison. The comparative aqueous resin dispersion for sealer (5) obtained had a nonvolatile content of 24.7%, a pH of 10.8 and a viscosity of 720c.
ps (B-type viscometer) and the characteristic value of the minimum film formation temperature of 0 ° C. or less were shown.

Test Method Primary Adhesion: The coating film was cut into 5 × 5 grids with a cutter knife at 3 mm intervals, a polyester adhesive tape was pressure-bonded, and then peeled off to examine the remaining state of the coating film.

◯: The coating film is not peeled at all Δ: The coating film is partially peeled off ×: The coating film is completely peeled off Warm water resistance: The test piece coated with the coating film is immersed in warm water at 60 ° C. for 5 days, and then for 2 days After drying at room temperature, the adhesion was examined by the same method as above.

Frost resistance: immersion in water at 10 ° C. for 2 hours → freezing in air at −20 ° C. for 2 hours as one cycle, 200 cycles were performed, and after drying in a greenhouse for 2 days, adhesion was examined by the same method as above. .

Topcoat suitability: A coating material obtained by the formulation shown in Table 1 was applied to a base material coated with an aqueous resin dispersion for a sealer to give a solid content of 40 / m ^2.
After coating and drying in a hot air dryer at 120 ° C. for 10 minutes, the adhesion was examined by the same method as in the primary adhesion test.

Table 1 Topcoat paint blending part Water 64.6 Democall EP (manufactured by Kao Corporation) 2.0 Nobuko 8034 (manufactured by San Nobuco Corporation) 0.
3 Titanium oxide (rutile type) 54.0 Kaolin 6.0 Acrylic 210E Note) 146.7 CS-12 (manufactured by Chisso Corporation) 9.5 5% ADECANOL UH-420 (manufactured by Asahi Denka Co., Ltd.) 1 0.0 Total 284.1 Note) Accreset 210E is an acrylic emulsion manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd., with a nonvolatile content of 50%.

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Claims (5)

[Claims] 1. A sealer characterized by adding a hydrophobic epoxy resin emulsified with polyvinyl alcohol having a saponification degree of 80 mol% or more to an aqueous resin dispersion obtained by emulsion-polymerizing a vinyl-based polymerizable monomer. A method for producing an aqueous resin dispersion. 2. An aqueous resin dispersion 1 containing polyvinyl alcohol.
The method for producing an aqueous resin dispersion for a sealer according to claim 1, which is used in a range of 1 to 40 parts by weight based on 00 parts by weight of the solid content. 3. The degree of polymerization of polyvinyl alcohol is 200 to
The method for producing an aqueous resin dispersion for a sealer according to claim 1, wherein the range is 2600. 4. An aqueous resin dispersion 10 containing a hydrophobic epoxy resin.
The method for producing an aqueous resin dispersion for a sealer according to claim 1, which is used in a range of 1 to 40 parts by weight in terms of solid content relative to 0 parts by weight. 5. The epoxy equivalent of the hydrophobic epoxy resin is 15
The method for producing an aqueous resin dispersion for a sealer according to claim 1, which is in the range of 0 to 3,500.