JPH08157773A - Aqueous undercoating dispersion for inorganic porous substrate - Google Patents

Abstract

PURPOSE: To prepare an aq. undercoating dispersion for an inorg. porous substrate which is free from problems of unsatisfactory impregnation, unsatisfactory adhesion, water resistance, and freeze-thaw resistance. CONSTITUTION: An aq. undercoating dispersion, for an inorg. porous substrate, comprising: an aq. resin dispersion prepd. by solution-polymerizing 100 pts.wt. radical-polymerizable ethylenically unsatd. monomer with 10 pts.wt. reactive surfactant having in its molecule a radical-polymerizable unsatd. double bond in the presence of a polymerization initiator and a polymerization solvent, subjecting the resultant resin soln. to phase conversion in water, and removing the polymerization solvent; and polyvinyl alcohol, the aq. resin dispersion and the polyvinyl alcohol being in the form of a mixture in a wt. solid content ratio of (70:98) to (30:2).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous undercoat dispersion for an inorganic porous substrate, more specifically, it has been remarkably improved in adhesion, water resistance, freeze-thaw resistance to the inorganic porous substrate, Lightweight concrete, mortar, and asbestos cement made of a mixture of an aqueous resin dispersion in which a dispersion medium is phase-converted into water in a solvent-type acrylic resin copolymerized with a reactive surfactant and polyvinyl alcohol (hereinafter referred to as PVA). Board,
Aqueous undercoat dispersion for inorganic porous substrate that forms a coating film with good adhesion, water resistance, freeze-thaw resistance and the like when applied to various inorganic substrates such as calcium silicate plate, slate or gypsum board. Regarding

[0002]

2. Description of the Related Art As inorganic porous base materials, lightweight concrete, mortar, asbestos cement board, calcium silicate board,
There is slate or gypsum board, etc., both of which are porous and thus have low surface strength and easily absorb moisture, so if the surface is just finished with makeup, bleeding, peeling, absorption of water or moisture will cause freeze-thawing. Repeating causes problems such as peeling of the finishing agent.
For the purpose of improving such peeling resistance, it is customary to apply a sealer to the surface of the inorganic substrate.

As the resin used for the sealer of the inorganic porous base material, a moisture-curable urethane resin or a solvent type resin is used. However, toxicity and the risk of fire due to the use of organic solvents and environmental pollution have become problems, and there is a strong demand for making them aqueous.

Various water-based sealers containing water-soluble resins or water-dispersible resins as main components have been investigated.
Water-soluble resin as the main component has water resistance, and water-dispersible resin as the main component has poor impregnability and adhesion to the substrate, and must maintain peel resistance for a long time. Is difficult. Further, a method of mixing and using a water-soluble resin and a water-dispersible resin has been studied, and for example, a method of blending PVA with a specific polymer aqueous emulsion (Japanese Patent Laid-Open No. 53-97).
No. 018) has been proposed, but there are drawbacks such as insufficient impregnation into the base material, and a satisfactory water-based sealer has not been obtained. Further, in the epoxy-based sealer improved with such drawbacks, since it is a two-liquid mixed type, it is not easy to handle and there is a problem in toxicity.

[0005]

As a result of various studies, the present inventors have found that in the production of an aqueous resin dispersion of a phase-converted aqueous dispersion resin and a specific PVA, insufficient impregnation into an inorganic substrate, insufficient adhesion, It is to solve the above problems such as water resistance and freeze-thaw resistance.

[0006]

The first aspect of the present invention is to provide a reactive surfactant 10 having 100 parts by weight of a radically polymerizable ethylenically unsaturated monomer and a radically polymerizable unsaturated double bond in the molecule. The resin solution obtained by solution polymerization in the presence of a polymerization initiator and a polymerization solvent in parts by weight or less is phase-converted into water, and the aqueous resin dispersion and polyvinyl alcohol obtained by removing the polymerization solvent are solid by weight. 70-9 by the ratio
It is an aqueous undercoat dispersion for an inorganic porous substrate which is a mixture of 8/30 to 2. The second invention is 5 parts by weight or less per 100 parts by weight of the radically polymerizable ethylenically unsaturated monomer of the reactive surfactant having a radically polymerizable unsaturated double bond in the molecule. It is an aqueous undercoat dispersion for an inorganic porous substrate of the invention.

The third invention is that the degree of polymerization of PVA is from 200 to 200.
2400, an aqueous undercoat dispersion for an inorganic porous substrate according to the first invention, having a saponification degree of 85 mol% or more.

The ethylenically unsaturated monomers used in the present invention include (meth) acrylic acid alkyl ester monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and methacrylic acid. Methyl, ethyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, as an acid-based monomer,
Acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, para-vinyl benzoic acid, para-vinyl benzene sulfonic acid, other styrene, alpha methyl styrene,
Vinyltoluene, vinyl acetate, vinyl propionate, etc. can be used.

In the case of copolymerizing with an ethylenically unsaturated monomer, it is preferable to copolymerize with an acid-based monomer, and the amount of the acid-based monomer used depends on the copolymer to be obtained. The acid value is preferably in the range of 5 to 200. When the acid value is lower than 5, the system tends to become unstable at the phase conversion from the solvent system to the water system, and it is difficult to obtain a good emulsion. When the acid value is higher than 200, the viscosity of the system becomes high, This is because it may cause deterioration of water resistance of the coating film. Furthermore, when copolymerized using these acid-based monomers, all or part of these acids are neutralized with a basic substance such as triethylamine, dimethylaminoethanol, ammonia, etc., and then phase-converted into an aqueous system. You can also

Further, acrylamide and N- are mainly used for the purpose of adjusting fluidity and drying property and improving stability during resin storage.
Methylol acrylamide, hydroxyethyl acrylate, hydroxylpropyl acrylate, hydroxyethyl methacrylate and the like can be used. Further, ethylene glycol dimethacrylate, diallyl phthalate, divinylbenzene and the like can be used for the purpose of imparting a crosslinked structure to the film.

The reactive surfactant used in the present invention is an anionic or nonionic surfactant having at least one unsaturated double bond capable of radical polymerization in the molecule, for example, the following general formula (1) , Sulfosuccinate represented by (2) (commercially available products include, for example, Latemuru S-120P and S-180A manufactured by Kao Corporation, Sanyo Kasei Co., Ltd.).
Eleminol JS-2, etc.), an alkylphenol ether type represented by the general formula (3) (commercially available products are Aqualon HS-10 and RN-20 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).
Etc.)

General formula (1)

[0013]

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R ₁ : alkyl group having 12 to 30 carbon atoms M ₁ : Na, NH ₄ , K

General formula (2)

[0016]

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R ₁ : alkyl group having 12 to 30 carbon atoms M ₁ : Na, NH ₄ , K

General formula (3)

[0019]

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R ₂ : alkyl group having 8 to 12 carbon atoms X: H or SO ₃ M ₂ M ₂ : Na, NH ₄ , K n: 1 to 200

By using a reactive surfactant, a composition having a strong hydrophobic property and a low acid value are likely to be unstable at the time of phase conversion into an aqueous system, resulting in agglomerates or particles of the resulting resin dispersion. It is avoided that the larger diameter tends to lead to deterioration of stability over time and water resistance of the coating film,
Very good stability over time.

Upon polymerization, these may be used alone or in combination of two or more. These reactive surfactants are used in an amount of 10 parts by weight or less, preferably 5 parts by weight or less, based on 100 parts by weight of the ethylenic monomer. If the amount is more than 10 parts by weight, the polymerization reaction may not be completed, the viscosity of the reaction system or the obtained dispersion may be too high, and the water resistance of the coating film may be lowered.

Although it is possible to use a non-reactive surfactant at the time of synthesis or phase conversion, problems such as foaming and deterioration of water resistance of the coating film occur.

The polymerization initiator used in the present invention is capable of radically decomposing by heat or a reducing substance to cause addition polymerization of a monomer, and is a persulfate or a peroxide soluble in a monomer or a polymerization solvent. Oxides and azobis compounds. For example, ammonium persulfate, potassium persulfate, t-butyl hydroperoxide, t-butyl peroxy-
Examples thereof include 2-ethylhexanoate, benzoyl peroxide, azobisisobutyronitrile (AIBN), and azobisisovaleronitrile, but are not limited thereto.

As the polymerization solvent used in the present invention, an organic solvent generally used for polymerization of a solvent-based acrylic resin can be used, but it is preferably a good solvent for the acrylic resin obtained by the polymerization and easily mixed with water. It is desirable to use those which can be mixed and whose boiling point is lower than that of water. For example, methyl alcohol, ethyl alcohol,
Alcohol solvents such as isopropyl alcohol (IPA), ketone solvents such as acetone and methyl ethyl ketone,
Examples thereof include ester solvents such as ethyl acetate and butyl acetate, but are not limited thereto.

The PVA used in the present invention has a saponification degree of 8
It is 5 mol% or more. The use of PVA having a saponification degree of 80 mol% or less is not preferable because the hydrophilicity becomes strong and the water resistance is lowered. The weight mixing ratio is 70 to 98 / PVA2 to 30 (aqueous resin dispersion (solid content)).
Further, the degree of polymerization of PVA is 200 to 200 from the viewpoint of water resistance.
A range of 2400 is preferred.

The aqueous resin dispersion obtained by the present invention is
Although it can be used as a sealer for an inorganic porous substrate, a film forming aid, a pigment, a filler, a toner, a wetting agent, a defoaming agent and the like may be blended as necessary.

[0028]

The present invention will be described below with reference to examples. In the examples, “part” means “part by weight” and “%” means “% by weight”.

Example 1 A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser was charged with the reaction can amount shown in Table 1 and saturated with nitrogen gas. The drops in Table 1 are mixed in advance. After the internal temperature is raised to 82 ° C., benzoyl peroxide is added to uniformly dissolve the benzoyl peroxide, and then the dropping is started. The total amount is added dropwise over 2 hours, and benzoyl peroxide is added at the end of the addition. 2 more at 82 ° C
After heating and aging for an hour, the mixture is neutralized with triethylamine and water is added. Further, isopropyl alcohol used for polymerization (hereinafter abbreviated as IPA) is distilled off by heating, PVA is added under cooling, and the mixture is uniformly mixed and stirred to give a glass transition temperature (Tg) 2
An aqueous resin dispersion having a solid content of 30% and a viscosity of 720 cps was obtained at 0 ° C.

[0030]

[Table 1]

* 1 Eleminol JS-2 manufactured by Sanyo Kasei Co., Ltd. Active ingredient 38% * 2 PVA2 Saponification degree 98.5 Polymerization degree 1700 1
2% aqueous solution

Examples 2 to 6 In the same manner as in Example 1, the type of unsaturated monomer, the acid value, the type and amount of the reactive activator, the degree of saponification of PVA, the degree of polymerization, and the additives were changed. An aqueous resin dispersion was synthesized with the composition shown in 2.

[0033]

[Table 2]

* 2 PVA2 Saponification degree 98.5 Polymerization degree 1700 12% aqueous solution * 3 Latemur S-180A Kao Corporation active ingredient 30% * 4 Aqualon HS-10 Daiichi Kogyo Seiyaku Co., Ltd.
Active ingredient 98% * 5 PVA1 Saponification degree 88 Polymerization degree 1000 2
0% aqueous solution * 6 PVA3 Saponification degree 98.5 Polymerization degree 2000 1
2% aqueous solution * 7 PVA4 Saponification degree 98.5 Polymerization degree 24001
0% aqueous solution Comparative Examples 1 to 6 Example using a PVA saponification degree of 80 without using a reactive surfactant (Comparative Example 1), PV using a reactive surfactant
A Example using a saponification degree of 80 (Comparative Example 2), PVA using a reactive surfactant above the range of claims (Comparative Example 3), PVA using a reactive surfactant below the range of claims Example (Comparative Example 4), an aqueous resin dispersion was produced according to Example 1 with respect to the examples (Comparative Example 5) in which the reactive surfactant was within the claims.

[0035]

[Table 3]

* 2 PVA2 Saponification degree 98.5 Polymerization degree 1700 12% aqueous solution * 6 PVA3 Saponification degree 98.5 Polymerization degree 2000 1
2% aqueous solution * 8 PVA5 Saponification degree 80 Polymerization degree 300 2
0% aqueous solution

The solid content, viscosity and PH of the aqueous resin dispersions obtained in Examples and Comparative Examples were measured and the results are shown in Table 4. Also, adjust by adding a film forming aid to the aqueous resin dispersion,
20g on calcium silicate board and flexible board
/ M ² (dry) and dried with hot air at 130 ° C. for 10 minutes, and the adhesion to the substrate, hot water resistance, and freeze-thaw resistance were examined. The results are as shown in Table 5.

Test Method Primary Adhesion: The coating film was 5 × with a cutter-knife at 2 mm intervals.
After cross-cutting No. 5 and pressure bonding a cello tape, the peeled coating film was observed for the remaining state.

Warm water resistance: A test piece coated with a coating film was heated to 50 ° C.
The film was immersed in warm water for 7 days for observation of the state of the coating film, and dried for 2 days at room temperature to perform an adhesion test by the above method.

Freeze-thaw resistance: immersion in water at 10 ° C. for 2 hours,
A cycle of freezing in the air at -20 ° C for 2 hours was set as one cycle, 100 cycles were performed, and the coating film was observed and dried at room temperature for 2 days to perform an adhesion test by the above method.

As the judgment of the above test, ◯: the appearance of the coating film was not abnormal and the coating film was not peeled at all Δ: small blister was observed, and the coating film was partially peeled ×: large blister was observed, In addition, all the coating film peeled

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

INDUSTRIAL APPLICABILITY The aqueous resin dispersion of the present invention was able to obtain a coating film of an undercoat dispersion having good adhesion, water resistance and freeze-thaw resistance to an inorganic porous substrate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area C09D 133/04 PGF

Claims (3)

[Claims] 1. A polymerization initiator and polymerization of 100 parts by weight of a radically polymerizable ethylenically unsaturated monomer and 10 parts by weight or less of a reactive surfactant having a radically polymerizable unsaturated double bond in the molecule. The resin solution obtained by solution polymerization in the presence of a solvent is phase-converted into water, and the aqueous resin dispersion obtained by removing the polymerization solvent and polyvinyl alcohol are 70-98 / 30-2 by weight solid content ratio. An aqueous undercoat dispersion for an inorganic porous substrate, which is a mixture of 2. A reactive surfactant having a radical-polymerizable unsaturated double bond in the molecule is 5 parts by weight or less with respect to 100 parts by weight of the radical-polymerizable ethylenically unsaturated monomer. Aqueous undercoat dispersion for inorganic porous substrates as described. 3. The degree of polymerization of polyvinyl alcohol is 200 to
The aqueous undercoat dispersion for an inorganic porous substrate according to claim 1, which has a degree of saponification of 2400 and is 85 mol% or more.