JPH09110944A - Coating additive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating additive having an enhanced flat effect and having enhanced sealing properties. SOLUTION: An unsaturated polyester is suspension-polymerized with a vinyl monomer in an aqueous medium. The unsaturated polyester resin obtained is used after being pulverized into particles having an average particle diameter of 5-20μm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel coating additive. More specifically, the present invention relates to an additive for coatings, which has good matteness and sealing properties of a dried coating film.

[0002]

2. Description of the Related Art Conventionally, various additives have been added to paints to give them functions. Among them, for paints that form a matte coating film and paints that have sealing properties,
At present, the function is imparted by adding an inorganic substance such as an inorganic pigment or an organic substance such as an organic polymer.

As a general inorganic additive, silica,
Powders of calcium carbonate, talc, clay, alumina, etc. are used. However, a coating film obtained from a coating material containing an inorganic additive has a drawback that the dispersibility and adhesion to the coating material resin are poor with respect to the matting property, and the coating film has poor water resistance and processability. there were. Further, regarding the sealing property, there is a drawback that the polishing property is deteriorated when an inorganic additive is used at the time of polishing after applying the coating material. In order to overcome such drawbacks, the use of organic polymers has been newly proposed.

Typical organic polymers include resins such as polyolefin-based, urethane-based, acrylic-based, and polyester-based resins, which are often used in the form of spherical or amorphous fine powder. Among the proposed organic polymers, the unsaturated polyester resin is a thermosetting resin, so when it is made into a matte paint, it can withstand the heating during baking and a good matte effect can be obtained. It is said to be preferable. Further, although the form of these fine powders may be in the form of particles, the amorphous form has a higher matte effect. As a method of obtaining an unsaturated polyester resin fine powder, there is a method of mechanically pulverizing a gel-like polymer using a pulverizer, as disclosed in JP-B-51-8975. When the amorphous fine powder thus obtained is used, a good matte coating film can be obtained. However, although the matting effect is good, gloss unevenness, which is unlikely to occur when spherical fine powder is used, often occurs.

[0005]

It is possible to obtain an additive for paints that further enhances the effects of matting properties and sealing properties, which have not been obtained from conventional inorganic additives and organic polymers.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that an unsaturated polyester and a vinyl monomer are used as an additive for matting and sealing paints in an aqueous medium. The inventors have found that it can be obtained by pulverizing a granular unsaturated polyester resin obtained by suspension polymerization in the above, and have completed the present invention.

That is, in the present invention, an unsaturated polyester and a vinyl monomer are suspension-polymerized in an aqueous medium, and the resulting unsaturated polyester resin is pulverized to an average particle size of 5 to 20 μm,
It relates to an additive for paints characterized by being used.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The unsaturated polyester used in the present invention is produced from an unsaturated dibasic acid and a glycol compound. The unsaturated dibasic acid used here is preferably an α, β-unsaturated dibasic acid such as maleic anhydride, itaconic acid, citraconic acid, mesaconic acid, chlorinated maleic acid, etc. Alternatively, two or more kinds are used. Further, phthalic anhydride, isophthalic acid, terephthalic acid, monochlorophthalic acid, dichlorophthalic acid, trichlorophthalic acid, het acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, endomethylenetetrahydrophthalic anhydride to the unsaturated dibasic acid, Adipic acid, succinic acid,
It does not matter at all to add an appropriate amount of a saturated dibasic acid such as sebacic acid, glutaric acid or pimelic acid.

On the other hand, examples of the glycol compound include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, 1,3 butylene glycol, 2,3 butylene glycol, 1,4 butylene glycol, neopentyl glycol and hexylene. Glycol, octylene glycol, bisphenol A dioxyethyl ether adduct,
Bisphenol A dioxypropyl ether adduct, hydrogenated bisphenol A, or alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide are preferable, and polyhydric alcohols such as trimethylolpropane and glycerin may be used in combination, if necessary. It doesn't matter.

Vinyl monomers usable in the present invention include styrene, α-methylstyrene, vinyltoluene,
Examples thereof include diallyl phthalate, vinyl acetate, methyl methacrylate, glycidyl methacrylate, and styrene is particularly preferable.

The unsaturated polyester resin of the present invention can be usually obtained by the following method. First, an unsaturated dibasic acid and a glycol compound are subjected to an esterification reaction to form an unsaturated polyester, and this and a vinyl monomer are subjected to suspension polymerization in an aqueous medium in the presence of a polymerization initiator to obtain a spherical unsaturated polyester. A slurry containing the resin is obtained. The unsaturated polyester resin of the present invention is obtained by separating the slurry with a centrifuge or the like and drying. The esterification reaction between the unsaturated dibasic acid and the glycol compound is usually carried out by a known method.

In the present invention, the ratio of the unsaturated polyester and the vinyl monomer during suspension polymerization varies depending on the type of each of the unsaturated polyester and the vinyl monomer, and thus it is not particularly limited, but usually it is not. Vinyl monomer 10 per 100 parts by weight of saturated polyester
˜150 parts by weight, preferably 20 to 100 parts by weight.

As the polymerization initiator, organic peroxides such as methyl ethyl ketone peroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, t-butyl peroxide, azobisbutyronitrile, azobis (2,4- Dimethylvaleronitrile)
Commonly known compounds such as azo compounds such as, hydrogen peroxide, and water-soluble peroxides such as potassium persulfate are used. The addition amount of these is slightly different depending on the types of raw materials such as unsaturated dibasic acid, glycol compound and vinyl monomer, the conditions of polymerization, etc., but is 0.1 to 10 relative to 100 parts by weight of the total amount of each raw material. Weight parts are preferred.

If necessary, cobalt naphthenate,
It is no problem to add 0.1 to 2.0 parts by weight of a curing accelerator such as N, N'-dimethylaniline or cobalt octenoate to 100 parts by weight of the total amount of each raw material. In the present invention, the aqueous medium may be water itself, but in order to prevent deformation of particles during the polymerization of the suspension polymer, excessive growth, or secondary aggregation of particles, an appropriate amount of a suspension stabilizer is added. preferable.

The suspension stabilizer is not particularly limited, and known ones can be used. For example, water-soluble polymeric substances such as polyvinyl alcohol, methyl cellulose, hydroxy cellulose, polyacrylic acid, water-insoluble inorganic salts such as magnesium oxide and calcium phosphate, surfactants such as sodium alkylbenzene sulfonate, polyoxyethylene nonyl phenyl ether, etc. Are used alone or in combination. The amount of addition depends on the type of the above raw materials, the conditions of polymerization, etc.
A range of 1.0 to 30 parts by weight is preferable with respect to parts by weight.

The reaction temperature, reaction time, stirring conditions of the aqueous medium, etc. during suspension polymerization in the present invention are appropriately selected depending on the kind and amount of the raw materials, the desired particle size of the polymer, etc. Be implemented. For example, the polymerization temperature is usually about 20 although it varies depending on the type and amount of the polymerization initiator added.
To 100 ° C, preferably 60 to 90 ° C, and the polymerization time is usually about 2 to 20 hours, preferably 4 to 15 hours.

Further, it is preferable to carry out the polymerization while stirring the aqueous medium in a state of being sealed in an atmosphere of an inert gas such as nitrogen or carbon dioxide as in the case of general suspension polymerization.
The shape of the unsaturated polyester resin of the present invention obtained by suspension polymerization is a fine spherical shape, but the particle size and particle size distribution are such that the type and amount of the suspension stabilizer to be added, the stirring speed, the unsaturated polyester and vinyl. It can be adjusted by a method of adding a mixed liquid of monomers.

Particularly, when the average particle size of the obtained unsaturated polyester resin particles is 100 to 300 μ, preferable results can be obtained when the unsaturated polyester resin particles are pulverized into a coating material. , The average particle size is 10
If necessary, the particle diameters may be made uniform by classification so that the particle diameter becomes 0 to 300 μm.

After washing and drying the unsaturated polyester resin obtained as described above, various pulverizers, for example,
Mechanically crushing with a crusher such as a roll crusher, a hammer mill, a ball mill, a jet mill, an atomizer, etc., it is possible to obtain an unsaturated polyester resin useful as an additive for paints, which has good matting properties and sealing properties. A resin having an average particle size of 5 to 20 μ pulverized in this way can be used as a coating additive having a good matting property and a good sealing property.

When the average particle diameter of the coating additive is less than 5 μ, the matte effect is small and a large amount of powder is added to the coating in order to form a low-gloss coating film. As a result, the viscosity of the coating is increased. The harmful effect of becoming high occurs. On the other hand, when the average particle size exceeds 20 μ, the matting effect is good, but the smoothness of the coating film surface is poor.

Although the reason why the unsaturated polyester resin of the present invention is effective in matting properties and sealing properties is not clear, it is obtained by suspension polymerization of an unsaturated polyester and a vinyl monomer in an aqueous medium. By crushing the spherical resin thus obtained, a part of the spherical body remains, and it is considered that the above effect is further exerted from the balance with the linear portion.

The unsaturated polyester resin thus obtained is added as a paint additive having good matteness and sealing properties, and the kind of paint is not particularly limited. For example, any paint such as melamine alkyd type, unsaturated polyester type, epoxy type, polyurethane type, polyvinyl chloride type, acrylic type, phenol type, silicone acrylic type may be used.

[0023]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. In the following, all parts or% mean parts by weight or% by weight. Production Example 1 Isophthalic acid and maleic anhydride as dibasic acids were mixed at 1.5 mol and 3.0 mol, respectively, and propylene glycol and ethylene glycol as glycol compounds were mixed at 3.5 mol and 1.45 mol, respectively, This is subjected to an esterification reaction at a temperature of 180 to 210 ° C. in a nitrogen atmosphere,
An unsaturated polyester was obtained. Next, 100 parts of this unsaturated polyester is dissolved in 50 parts of styrene monomer,
A viscous mixture was prepared, and 1.5 parts of azobisisobutyronitrile as a polymerization initiator was further added to this mixture and mixed again to obtain a uniform mixture. In addition, an aqueous solution prepared by dissolving 1.5 parts of polyvinyl alcohol (PVA-217s manufactured by Kuraray Co., Ltd.) as a suspension stabilizer in 450 parts of ion-exchanged water was used as an aqueous medium, and the polymerization was performed in the aqueous medium while stirring. A homogeneous mixed solution to which an initiator was added was added dropwise, dispersed as droplets, and suspension polymerization was carried out at 70 ° C. for 3 hours and then at 85 ° C. for 2 hours. After the completion of the polymerization, the slurry containing the produced unsaturated polyester polymer is separated with a small centrifuge, washed with water, and then dried at 80 ° C. for 5 hours to obtain transparent unsaturated polyester resin particles having an average particle diameter of 200 μ. It was The unsaturated polyester resin particles obtained were pulverized with a roll crusher and an atomizer to obtain a coating additive 1 having an average particle diameter of 7 μm.

Production Example 2 The unsaturated polyester resin particles obtained in Production Example 1 were crushed with a roll crusher and an atomizer to give an average particle diameter of 3
μ of paint additive 2 was obtained.

Production Example 3 The unsaturated polyester resin particles obtained in Production Example 1 were crushed with a roll crusher and an atomizer to give an average particle diameter of 3
0 μ of coating additive 3 was obtained.

Production Example 4 1.0 mol of phthalic anhydride and maleic anhydride as dibasic acids, and 1.5 mol of propylene glycol and ethylene glycol as 1.5 mol glycol compounds, respectively, in proportions of 3.5 mol and 1.45 mol, respectively. After mixing, an esterification reaction was carried out in the same manner as in Production Example 1 to obtain an unsaturated polyester.
Next, this unsaturated polyester was dissolved in an equal weight of styrene monomer to obtain a viscous mixture. This mixture 1
1.5 parts of lauroyl peroxide as a polymerization initiator was added to 50 parts and mixed again to obtain a uniform mixed solution. Then, suspension polymerization was carried out in the same manner as in Production Example 1 to obtain transparent unsaturated polyester resin particles having an average particle diameter of 200 μ.
Further, the unsaturated polyester resin particles thus obtained were used in Production Example 1
The powder was pulverized in the same manner as described above to obtain a coating additive 4 having an average particle diameter of 9μ.

Production Example 5 A viscous mixture of the same unsaturated polyester as that obtained in Production Example 1 and a styrene monomer (the mixing ratio of the unsaturated polyester and the styrene monomer is also the same as in Production Example 1).
To 100 parts, 0.3 part of a 6% aqueous cobalt naphthenate solution as a curing accelerator and 1.0 part of methyl ethyl ketone peroxide as a polymerization initiator were added, and then uniformly mixed. Then, the homogeneous mixed solution was left standing on a stainless steel tray for 20 hours to be hardened, and then heated at 80 ° C. for 3 hours to be hardened again. Then, the obtained unsaturated polyester resin cured product was crushed by a roll crusher and an atomizer to obtain a coating additive 5 having an average particle diameter of 7 μm.

Production Example 6 A viscous mixture of the same unsaturated polyester as that obtained in Production Example 4 and a styrene monomer (the mixing ratio of the unsaturated polyester and the styrene monomer is the same as in Production Example 4) is used. Then, in the same manner as in manufacturing example 5,
This mixed liquid was cured and pulverized to obtain a coating additive 6 having an average particle diameter of 9μ.

Examples 1 to 8 and Comparative Examples 1 to 5 The following coating compositions were produced using the above coating additives 1 to 6. As a raw material resin for paint, Uban 136
(Mitsui Toatsu Chemical Co., Ltd., trade name, butylated urea melamine resin, non-volatile content 60%) and Ulix 210S (Mitsui Toatsu Chemical Co., Ltd., trade name, alkyd resin, non-volatile content 70%) used. As the curing agent, a 50% isopropanol solution of paratoluenesulfonic acid was used. These coating material resins, curing agents, and coating additives 1 to 6 are mixed and dispersed according to the composition and blending amount shown in Table 1 below, and an equivalent mixture of xylene / n-butanol is used as a diluting solvent. A coating composition was obtained by adjusting the solid content to be 55%. The paint containing the unsaturated polyester resin fine powder was applied to a tin plate and a saber / cover birch plywood, allowed to stand at room temperature for 30 minutes, and then dried at 50 ° C. for 30 minutes. The tin plate was coated such that the film thickness after drying was 30 μm. Further, for the saber-birch plywood, the coating amount was 50 μm after drying, assuming that there was no suction.

The coating compositions of the examples and comparative examples are shown in Table 1. The evaluation results are shown in Table 2.

[0031]

[Table 1] * 1: PTS paratoluene sulfonic acid 50% isopropanol solution

[0032]

[Table 2]

* 2: Gloss Measured at 60 ° specular reflectance, rounded up to the nearest whole number. * 3: Gloss unevenness The matte state of the coating film was visually evaluated. ◯: The coating film is in a uniform and completely matt state. X: The coating film has uneven gloss. * 4: Finger touch The coating film was touched with a finger and evaluated according to the following criteria. ○: Good with uniform feel. X: A rough feel is recognized. * 5: Dry film thickness The film thickness after drying was measured for the one applied to the plywood.

[0034]

As described in detail above, the unsaturated polyester of the present invention and the vinyl monomer are subjected to suspension polymerization in an aqueous medium,
Finely obtained by pulverizing a bulk polymer of a conventional unsaturated polyester and vinyl monomer by blending a coating material additive with a coating additive produced by pulverizing the obtained unsaturated polyester resin particles. It is possible to produce a coating material having excellent matting properties and filling properties from the powder.

Claims (1)

[Claims] 1. An additive for coatings, which is used by suspension-polymerizing an unsaturated polyester and a vinyl monomer in an aqueous medium, and pulverizing the obtained unsaturated polyester resin to an average particle size of 5 to 20 μm. .