JPH1112329A - Aqueous resin dispersion - Google Patents

Abstract

(57) [Problem] To provide a coating film having good adhesion to a base, water resistance, chemical resistance, and storage stability, which is a base resin for an undercoat, an intermediate coating, and a topcoat. A radical polymerizable ethylenically unsaturated monomer, a polyolefin, an emulsifier, a polymerization initiator, and water are radically polymerized as essential components. Aqueous resin dispersion with good water resistance, adhesion and storage stability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous resin dispersion having good water resistance and adhesion, and more particularly, to an aqueous resin dispersion having a polyolefin in a resin having a very fine particle size, water resistance and adhesion. And an aqueous resin dispersion having good storage stability.

[0002] The composition of the present invention comprises paints, synthetic resins, metals,
Glass, porcelain, gypsum, paper, wood, leather, even lightweight concrete, mortar, calcium silicate board, thread
As base coats for base coats, intermediate coats, and top coats applied to various substrates such as gypsum or gypsum boards, good coatings such as water resistance, adhesion, chemical resistance, storage stability, etc. Form.

[0003]

2. Description of the Related Art In recent years, from the viewpoint of effective utilization of resources and the like, organic solvent type paints are being replaced by aqueous type paints, especially aqueous emulsion type paints. However, ordinary water-based emulsion-type paints are required to be less dense than organic solvent-type paints because the emulsion-polymerized resin dispersed in water is fused when dried to form a film. Among them, in particular, the coating had poor water resistance and poor adhesion to the substrate.

[0004] In order to improve this drawback, a method of post-adding a polyolefin to an emulsion polymerization resin is known, but storage stability such as separation and gelation is poor.
The use of a large amount of a surfactant to improve the stability improves the performance, but has an adverse effect on the desired water resistance and the improvement in adhesion to the substrate, and has little effect of adding a polyolefin.

[0005]

As a result of various studies, the present inventors have provided an aqueous resin dispersion having good water resistance, adhesion to a substrate, and storage stability.

[0006]

[Means for Solving the Problems]

The first invention is an aqueous resin dispersion obtained by radically polymerizing a radically polymerizable ethylenically unsaturated monomer and a polyolefin with an emulsifier, a polymerization initiator and water as essential components.

The second invention is the aqueous resin dispersion according to the first invention, wherein the average particle diameter of the aqueous resin dispersion is 150 nm or less.

The third invention is the aqueous resin dispersion according to the first or second invention, wherein an oil-soluble polymerization initiator having a solubility in water of 0.3% by weight or less is used.

A fourth invention is the aqueous resin dispersion according to the first to third inventions, wherein a reactive emulsifier is used as an emulsifier.

The fifth invention is characterized in that a monomer having a carboxyl group is used as a radical polymerizable ethylenically unsaturated monomer in an amount of 0.5 to 5% by weight based on all monomers. An aqueous resin dispersion according to the first to fourth inventions.

According to a sixth aspect of the present invention, the amount of oil droplets of the dropped monomer is 0.1.
The aqueous resin dispersion according to any one of claims 1 to 5, wherein the aqueous resin dispersion is 5 µm or less.

The ethylenically unsaturated monomer used in the present invention is a monomer comprising an alkyl ester of (meth) acrylic acid, such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate,
(Meth) acrylates such as methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, and styrene, alpha methyl styrene, vinyl toluene, vinyl acetate, and vinyl propionate , Acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide, N-methylolacrylamide, hydroxyethyl acrylate, hydroxylpropyl acrylate, hydroxyethyl methacrylate, ethylene glycol dimethacrylate, diallyl phthalate, divinylbenzene, glycidyl Methacrylate or the like can be used.

Further, as the monomer having a carboxyl group, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and the like are used in combination because the stability during production or storage of the aqueous resin dispersion is improved. Is preferred. For this purpose, it is preferable to use a monomer having a carboxyl group in an amount of 0.5 to 5 parts by weight based on all monomers. When the amount is less than 0.5 part by weight, the polymerization stability and the viscosity stability with the lapse of time are poor. When the amount is more than 5 parts by weight, the water resistance of the obtained film is deteriorated.

[0015] Further, acrylamide, N-
Methylol acrylamide, hydroxyethyl acrylate, hydroxylpropyl acrylate, hydroxyethyl methacrylate and the like can be used. Further, ethylene glycol dimethacrylate, diallyl phthalate, divinylbenzene, glycidyl methacrylate and the like can be used for the purpose of imparting a crosslinked structure to the film. For these purposes, one or more of these are used in combination.
These are desirably used in an amount of 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on all monomers. When the amount is less than 0.1 part by weight, the water resistance of the obtained film is poor, and when the amount is more than 10 parts by weight, cracks and the like occur in the film.

Also, for the purpose of providing a crosslinked structure to the film and further improving the adhesion to the substrate, organic alkoxysilane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and -Glycidoxypropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, hexyltriethoxysilane, heptyltriethoxysilane, octyltriethoxysilane , Nonyltriethoxysilane,
Decyltriethoxysilane, undecyltriethoxysilane, dodecyltriethoxysilane, tetradecyltriethoxysilane, pentadecyltriethoxysilane, hexadecyltriethoxysilane, heptadecyltriethoxysilane, octadecyltriethoxysilane, nonadecyltriethoxy Silane, eicosyltriethoxysilane, and mixtures thereof.

The polyolefins used in the present invention include resins obtained by chlorinating polyolefins such as polyethylene and polypropylene to a chlorine content of 60% or more. Upon polymerization, one or more of these may be used as a mixture. These are preferably used in an amount of 0.1 to 20 parts by weight, more preferably 0.5 to 20 parts by weight, per 100 parts by weight of the radically polymerizable ethylenically unsaturated monomer.
10 parts by weight. When the amount of the polyolefin is more than 20 parts by weight, the reactivity with the radically polymerizable ethylenically unsaturated monomer is reduced, so that a residual monomer is generated or a large amount of aggregates is generated. In addition, at the time of polymerization, it is preferable to dissolve the polyolefin in the dropped monomer to make the oil droplet diameter 0.5 μm or less, and if the oil droplet diameter is 0.5 μ or more, the polymerization stability is poor and aggregates are easily generated. . As a method of reducing the oil droplet diameter, a homomixer,
A line mixer, a high-pressure homogenizer, or the like can be used. However, in order to reduce the oil droplet diameter to 0.5 μm or less, a pipeline mixer that has a particularly narrow oil droplet diameter distribution and can be made fine in a short time is suitable. Further, as a method for measuring the oil droplet diameter, a fine particle diameter measuring device by a laser analysis method, an optical microscope, or the like can be used.

The reactive emulsifier used in the present invention is an anionic or nonionic emulsifier having one or more radically polymerizable unsaturated double bonds in the molecule. For example, the following general formulas (1) and (2) (For example, commercially available products such as Latemul S-120P and S-180A manufactured by Kao Corporation, Eleminor JS-2 manufactured by Sanyo Chemical Co., Ltd.), and a general formula (3) (A commercially available product, such as Aqualon HS-10 and RN-20 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

General formula (1)

[0020]

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General formula (2)

[0022]

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General formula (3)

[0024]

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In the emulsion polymerization, one or more of these may be used as a mixture. These emulsifiers are desirably used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the radically polymerizable ethylenically unsaturated monomer. If the amount is more than 10 parts by weight, the particle diameter becomes small, but as a large amount of emulsifier is used, the water resistance of the coating film is deteriorated as an adverse effect.
Further, when these emulsifiers have no reactivity,
Even if a stable resin dispersion is obtained, a decrease in water resistance due to elution of the activator is inevitable.

Another feature of the present invention resides in that an oil-soluble initiator is used as a polymerization initiator. In place of the oil-soluble polymerization initiator, water-soluble persulfates, peroxides, azobis compounds, etc. are subjected to redox radical decomposition by heat or a reducing substance to cause monomer polymerization, and the particle size in the polymerization process is reduced. And the water resistance of the film deteriorates. Examples of the oil-soluble initiator include tert-butyl perbenzoate.
G, lauryl peroxide, benzoyl peroxide, te
Preferred are rt-butyl hydroperoxide, azobisisobutyronitrile, azobisdimethylbutyronitrile, azobisvaleronitrile and the like. These oil-soluble initiators can be used alone, or may be used in a redox type in combination with a reducing agent such as sodium erythorbic acid.

The oil-soluble initiator is used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the radically polymerizable ethylenic monomer.

In the present invention, copper ions such as cupric sulfate and cupric chloride, and transition metal ions such as ferric sulfate and ferric chloride are added to the water charged in the reaction vessel in an amount of 10 ⁻⁷ to 10 ^−. It is desirable to add in the range of ⁵ mol / liter.

The aqueous resin dispersion obtained according to the present invention comprises:
Coloring agents such as dyes and pigments, fillers, etc. can be blended. Synthetic resins, metals, glass, ceramics, plaster, paper, wood, leather, lightweight concrete, lightweight foam concrete, mortar, silicon It can be used as a topcoat paint for calcium carbonate plates, slates, gypsum boards, etc., paint binders, paper processing agents, fiber treatment agents and the like.

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

Example 1 A reactor equipped with a stirrer, a thermometer, a dropping funnel and a reflux reactor was charged with the amount of the reactor shown in Table 1, and saturated with nitrogen gas. The oil droplet diameter of the droplets in Table 1 is reduced to 0.5 μm or less in advance by a pipeline mixer (line mixer). Internal temperature 80
After the temperature was raised to ° C, the amount of the polymerization initiator in the reactor was added, and after 5 minutes, the dropwise addition was started. The amount was dropped in 2 hours,
After aging for another 2 hours,
Adjusted to ~ 9. The measurement of the oil droplet diameter and the particle diameter of the aqueous resin dispersion were measured by a laser analysis particle diameter measuring apparatus (Nanosizer manufactured by Coulter, Inc.). 35.0% solids,
A resin dispersion having a viscosity of 500 cps and a particle diameter of 120 nm was obtained.

[0032]

[Table 1]

Examples 2 to 6 Resin dispersions were obtained in the same manner as in Example 1 except that the type and amount of the ethylenic monomer and polyolefin, the alkoxysilane monomer, and the reactive emulsifier were changed.

[0034]

[Table 2]

The polymerization stability and particle size of the aqueous resin dispersion obtained from the examples were measured, and the results are shown in Table 3.
The aqueous resin dispersion was adjusted by adding a film-forming aid and the like, and a water resistance test, a freeze / thaw test, a chemical resistance test, and a water resistance test of the resin film were performed. The results were as shown in Table 4.

Test method Preparation of Coating Film The aqueous resin dispersion was adjusted with a film forming aid (Texanol) so that the MFT was 0 ° C.

2. Water resistance test method Apply on a slate plate with a brush to a thickness of 0.5 mm, dry at room temperature for 72 hours at room temperature, immerse in 50 ° C warm water for 7 days, and visually check for blisters etc. I do. Judgment criteria 5: good (no abnormality) 1: bad (significant change in appearance over the entire surface)

3. Freezing and thawing test method 2 hours of immersion in water at 20 ° C. · 2 hours of freezing in −20 ° C. water were defined as 1 cycle, and 30 cycles were performed, and the external appearance of the coating film was visually observed and loupe. Judgment criteria 5: good (no abnormality) 1: bad (significant change in appearance over the entire surface)

4. Chemical resistance test method Apply on a slate plate with a brush to a thickness of 0.5 mm, dry at room temperature for 72 hours at room temperature, immerse in a 5% by weight aqueous sodium hydroxide solution for 7 days, and check for blisters. Judge with the naked eye. Judgment criteria 5: Good (no abnormality at all) 1: Bad (significant change in appearance is observed on the entire surface)

5. Water permeability test method A JIS K was applied to a coated plate which was applied on a slate plate with a brush to a thickness of 0.5 mm and dried at room temperature for 72 hours at room temperature.
The test was performed according to the -5400 permeability test method. The water permeability was determined 24 hours later. Judgment criteria 5: good (water permeability 0.3 ml or less) 1: poor (water permeability 3.0 ml or more)

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

The aqueous resin dispersion of the present invention comprises a synthetic resin,
It can be applied to various substrates such as metal, glass, porcelain, gypsum, paper, wood, leather, etc. without undercoating. Furthermore, lightweight concrete, lightweight foam concrete, mortar, calcium silicate board, It forms a good coating film for application to various inorganic base materials such as a slate plate or gypsum board. Further, it could be applied on the undercoat paint applied to these substrates, and a coating film having good water resistance, chemical resistance and stain resistance could be formed.

Claims (6)

[Claims] 1. A resin dispersion obtained by radical polymerization of a radically polymerizable ethylenically unsaturated monomer, a polyolefin, an emulsifier, a polymerization initiator and water as essential components. 2. The aqueous resin dispersion has an average particle size of 150 nm.
2. The aqueous resin dispersion according to claim 1, which is excellent in water resistance, adhesion, and storage stability. 3. An oil-soluble polymerization initiator having a solubility in water of 0.3% by weight or less is used.
2. The aqueous resin dispersion according to any one of 2. 4. The aqueous resin dispersion according to claim 1, wherein a reactive emulsifier is used as the emulsifier. 5. The method according to claim 1, wherein a monomer having a carboxyl group is used as a radically polymerizable ethylenically unsaturated monomer in an amount of 0.5 to 5% by weight based on all monomers. 5. The aqueous resin dispersion according to any one of 4. 6. The aqueous resin dispersion according to claim 1, wherein oil droplets of the dropped monomer are 0.5 μm or less.