JPH1112331A - Aqueous resin dispersion - Google Patents

Abstract

(57) [Abstract] [Problem] It can be applied on an undercoat paint, and has water resistance, adhesion,
Provide a good coating film such as chemical resistance. The radical polymerization is performed by using radically polymerizable ethylenically unsaturated monomers, polyurethane, an emulsifier, a polymerization initiator, and water as essential components, and making oil droplets of a dropping monomer 0.5 μm or less. Aqueous resin dispersion.

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 excellent water resistance and adhesion, and more particularly to an aqueous resin dispersion having polyurethane in a molecular structure, having an extremely fine particle diameter, and having excellent water resistance and adhesion. It relates to an aqueous resin dispersion.

[0002] The composition of the present invention comprises paints, synthetic resins, metals,
Base resin for base coat, intermediate coat, top coat applied to various base materials such as glass, porcelain, gypsum, paper, wood, leather, and even lightweight concrete, mortar, calcium silicate board, slate, or gypsum board To form a coating film having good water resistance, adhesion and chemical resistance.

[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 for paints because the emulsion polymerization type resin dispersed in water fuses upon drying to form a film, and the denseness of the film is poorer than that of organic solvent-type paints. Among the performances, there was a defect that the water resistance of the film and the adhesion to the substrate were particularly poor.

[0004] In order to improve this drawback, a method of post-adding polyurethane to an emulsion polymerization resin is known, but there are problems such as separation and gelation. Emulsion stability,
The problem can be solved by using a large amount of a surfactant, but this has an adverse effect on water resistance and adhesion to a substrate, and there is almost no effect of adding polyurethane.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aqueous resin dispersion having good water resistance and good adhesion to a substrate.

[0006]

[Means for Solving the Problems]

The first invention comprises a radically polymerizable ethylenically unsaturated monomer, a polyurethane, an emulsifier, a polymerization initiator,
An aqueous resin dispersion comprising water as an essential component and radical polymerization with an oil droplet of a dropped monomer of 0.5 μm or less.

A 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 has a solubility in water of 0.3% by weight.
The aqueous resin dispersion according to any one of the first to second inventions, wherein the following oil-soluble polymerization initiator is used.

The fourth invention is the aqueous resin dispersion according to any one of the first to third inventions, wherein a reactive emulsifier is used as the 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 any one of the first to fourth inventions.

The radically polymerizable ethylenically unsaturated monomer used in the present invention includes methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and the like.
Alkyl (meth) acrylates such as 2-ethylhexyl methacrylate, octyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, styrene, alpha methyl styrene, vinyl toluene, vinyl acetate, 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, divinyl benzene,
Glycidyl methacrylate, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane and the like can be used.

Acrylic acid, methacrylic acid, maleic acid,
When a monomer having a carboxyl group such as fumaric acid or itaconic acid is used in combination as a radically polymerizable ethylenically unsaturated monomer, stability during production or storage of the aqueous resin dispersion is preferably improved. For this purpose, a monomer having a carboxyl group is added in an amount of 0.5 to
It is preferable to use 5 parts by weight. 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.

Acrylamide, N-methylolacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and the like can be used for the main purposes of adjusting fluidity and drying property and improving stability during storage of the resin. Further, ethylene glycol dimethacrylate, diallyl phthalate, divinylbenzene, glycidyl methacrylate, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane 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 may be used in combination. These are preferably 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. If the amount is less than 0.1 part by weight, the water resistance of the obtained film is poor, and if it is more than 10 parts by weight, cracks and the like occur in the film, which is not preferable.

The polyurethane used in the present invention is a publicly known and commonly used one. The polyurethane component is reacted with a polyol component and a polyisocyanate component.
It is obtained by extending the chain with a low molecular compound having at least two active hydrogens. Polyurethane is used in an amount of 0.1 to 10 based on 100 parts by weight of a radically polymerizable ethylenically unsaturated monomer.
It is preferable to use 0 parts by weight. When the amount of the polyurethane is more than 100 parts by weight, the reactivity with the radically polymerizable ethylenically unsaturated monomer is reduced, and the monomer remains or an aggregate is generated.

At the time of polymerization, it is preferable to dissolve polyurethane in a dropping monomer to make the oil droplet diameter 0.5 μm or less. When the oil droplet diameter is 0.5 μ or more, the polymerization stability is poor and aggregates are easily generated, which is not preferable. As a method for reducing the oil droplet diameter, a homomixer, a line mixer, a high-pressure homogenizer, or the like can be used. A suitable pipeline mixer 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, and Eleminol JS-2 manufactured by Sanyo Chemical Co., Ltd.) represented by the following general formula (4). (A commercially available product, such as Aqualon HS-10 and RN-20 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

General formula (1)

[0019]

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General formula (2)

[0021]

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General formula (3)

[0023]

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In radical polymerization, one or more of these may be used in combination. These emulsifiers are preferably 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. 10
If the amount is more than parts by weight, the particle diameter becomes small, but the water resistance of the coating film is deteriorated because a large amount of emulsifier is used. 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 is 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. Oil-soluble initiators include tert-butyl perbenzoate, 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:
Colorants such as dyes and pigments, fillers, etc. can be compounded, and synthetic resins, metals, glass, ceramics, gypsum, paper, wood, leather, lightweight concrete, lightweight cellular concrete, mortar, calcium silicate board, slate , A paint for top coating on gypsum board, a paint binder, a paper processing agent, a fiber treatment agent and the like.

[0028]

The present invention will be described below 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. For the amount of drop in Table 1, the oil droplet diameter is reduced to 0.5 μm or less in advance using a pipeline mixer. After the internal temperature was raised to 80 ° C., the amount of the polymerization initiator in the reactor was added, and dropping was started 5 minutes later. The solution was added dropwise over 2 hours, aged at 80 ° C. for another 2 hours, cooled, and adjusted to a pH of 8 to 9 with aqueous ammonia (25%).
Was adjusted. The measurement of the oil droplet diameter and the measurement of the particle diameter of the aqueous resin dispersion were performed by a laser analysis method particle diameter measuring apparatus (Nanosizer manufactured by Coulter, Inc.). An aqueous resin dispersion having a solid content of 38.5%, a viscosity of 800 cps and a particle diameter of 75 nm was obtained.

[0030]

[Table 1]

Examples 2 to 6 In the same manner as in Example 1, the raw materials shown in Table 2 were charged to obtain an aqueous resin dispersion.

[0032]

[Table 2]

The polymerization stability and particle size of the aqueous resin dispersion obtained from the examples were measured. 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 and a chemical resistance test of the resin film were performed. The results are shown in Table 3. The coating film was prepared by adding a film forming aid (Texanol) to the aqueous resin dispersion and adjusting the MFT to 0 ° C.

1. Water resistance test method A 10 Mil applicator is applied on a glass plate, dried at room temperature for 7 days at room temperature, immersed in warm water at 50 ° C for 3 hours, and visually checked for whitening, blisters, and the like. Judgment criteria 5: good (no abnormality) 1: bad (significant change in appearance over the entire surface)

2. Chemical resistance test method 10 Mil. It is applied with an applicator, dried at room temperature at room temperature for 7 days, immersed in a 5% by weight aqueous sodium hydroxide solution for 24 hours, and the degree of whitening is visually determined. Judgment criteria 5: Good (no whitening at all) 1: Poor (things with significant whitening all over)

3. Adhesion test method 10 Mil. The composition was applied with an applicator, dried at room temperature at room temperature for 7 days, and subjected to an adhesion test using a Goban eye. Judgment criteria 100/100: good (no peeling at all) 0/100: bad (all peeled)

[0037]

[Table 3]

[0038]

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, adhesion and chemical resistance could be formed.

Claims (5)

[Claims] 1. A radical polymerization wherein an ethylenically unsaturated monomer capable of radical polymerization, polyurethane, an emulsifier, a polymerization initiator, and water are essential components, and an oil droplet of a dropping monomer is 0.5 μm or less to perform radical polymerization. Aqueous resin dispersion. 2. The aqueous resin dispersion has an average particle size of 150 nm.
The aqueous resin dispersion according to claim 1, wherein: 3. An oil-soluble polymerization initiator having a solubility in water of 0.3% by weight or less is used.
3. 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.