JP2689374B2 - Paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a one-part, normally-dry acrylic coating composition capable of providing a coating film excellent in weather resistance, flexibility and stain resistance.

[Prior Art] In recent years, acrylic coatings based on acrylic polymers have been used to coat cracks in concrete and mortar in interior and exterior coatings for construction. In particular, the acrylic polymer can be made less sticky on the surface by properly controlling the glass transition temperature thereof, so that it is possible to prevent dust from adhering to the surroundings and achieve a beautiful finish.

[Problems to be Solved by the Invention] However, the acrylic paint is not always satisfactory in terms of flexibility of the coating film, and it is desired to develop a paint excellent in flexibility in addition to stain resistance. .

[Means for Solving Problems] The inventors of the present invention have conducted diligent research to solve such problems, and have found that the above-mentioned cause may exist in the polymer structure of the acrylic polymer. And continued to study.

Conventional acrylic paints usually have a so-called random copolymer obtained by copolymerizing acrylic monomers as a main component, but the present inventors have a glass transition temperature of −5 to −5.
The present invention has been completed by finding that the problem can be solved when a graft copolymer of 15 ° C. is used. That is, the present invention provides "an acrylic monomer and the following polymerizable peroxide (I),
At least one of (II) and (III) is polymerized at a temperature not higher than the decomposition temperature of the peroxide, and an acrylic monomer is graft-polymerized at a temperature not lower than the decomposition temperature of the peroxide. A coating composition containing a graft copolymer having a glass transition temperature of 5 to 15 ° C. obtained by the above.

However, integer of n = 1 to 2 R ₁ = hydrogen atom or alkyl group having 1 to ₂ carbon atoms R ₂ = straight chain alkyl group or branched alkyl group having 1 to 9 carbon atoms, phenyl group, or 1 to 3 carbon atoms Alkyl group, substituted phenyl group R ₃ = hydrogen atom or alkyl group having 1 to 4 carbon atoms R ₄ = alkyl group having 1 to 4 carbon atoms R ₅ = alkyl group having 1 to 4 carbon atoms R ₆ = 1 to 12 carbon atoms Represents an alkyl group or a cycloalkyl group having 3 to 12 carbon atoms. ”.

Acrylic monomers targeted in the present invention include acrylic acid, methacrylic acid, acrylonitrile, methyl acrylate, ethyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, benzyl acrylate, Examples thereof include glycidyl acrylate, methyl methacrylate, ethyl methacrylate, (iso) butyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, glycidyl methacrylate, acrylamide, methacrylamide, and n-methylol acrylamide. To be

 These may be used alone or in combination.

Further, copolymerizable monomers other than the above, such as ethylene, propylene, isobutylene, butadiene, chloroprene, vinyl chloride, vinylidene chloride, vinyl acetate, pyridine, styrene, chlorostyrene, 2-methylstyrene, divinylbenzene, etc. are also required. Can be copolymerized depending on

As the polymerizable peroxide, at least one kind may be used from the above-defined ones, and two or more kinds may be used in combination.

As the polymerizable peroxide defined by the general formula (I),
For example, t-butylperoxymethacryloxyethyl carbonate, t-butylperoxyacryloxyethyl carbonate, t-butylperoxymethacryloxyethoxyethyl carbonate, t-butylperoxyacryloxyethoxyethyl carbonate, and the like.

Further, the polymerizable peroxide defined by the general formula (II),
For example, t-butyl peroxyallyl carbonate, t-
Hexyl peroxyallyl carbonate, 1,1,3,3-tetramethylbutyl peroxyallyl carbonate, p-
Menthyl peroxyallyl carbonate, t-butyl peroxy methacryl carbonate, and the like.

Further, examples of the polymerizable peroxide defined by the general formula (III) include t-butylperoxyisopropyl fumarate and t-butylperoxyethyl fumarate.

In producing the graft copolymer of the present invention, first, the acrylic monomer (A) and the polymerizable peroxide (B) are polymerized in the first stage at a temperature not higher than the decomposition temperature of (B). .
The glass transition temperature of the copolymer is advantageously in the range of -50 to 0 ° C. Flexibility is imparted by such adjustment. If it is less than -50 ° C, the stain resistance is poor, and if it is 0 ° C or more, the flexibility is insufficient. Then, the same type or different type of acrylic monomer as in the first step is graft-polymerized to the obtained copolymer.
The finally obtained graft copolymer and the glass transition temperature are adjusted to -5 to 15 ° C. When the glass transition temperature is -5 ° C or lower, the stain resistance is lowered, and conversely, when the glass transition temperature is 15 ° C or higher, the flexibility is lacking.

The graft copolymer of the present invention is obtained by a radical polymerization method using a radical polymerization initiator. As the polymerization method, known polymerization techniques such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization are used.

The first step of copolymerizing (A) and (B) is appropriately selected from a temperature range of 10 to 90 ° C. at which decomposition of the peroxide group of (B) is suppressed. Radical polymerization initiators in this range include isobutyryl peroxide, diisopropyl peroxide carbonate, di (2-ethylhexyl) peroxydicarbonate, t-butylperoxypivalate, lauroyl peroxide, benzoyl peroxide and azobis. Examples thereof include isobutyronitrile and azobisdimethylvaleronitrile.

The second stage reaction is carried out at or above the decomposition temperature of the peroxide group (B). Solution polymerization is suitable for use as a one-component, always-dry coating resin, and examples of the solvent include toluene, xylene, ethylene acetate, butyl acetate, methyl ethyl ketone, and methyl isobutyl ketone.

The graft copolymer does not necessarily have to be isolated from the reaction solution, and a composition containing the copolymer as the reaction solution is also used as a paint.

The resin composition of the present invention is used as a clear paint or a colored paint. When used as a coloring paint, as pigments, extenders such as calcium carbonate, kaolin, talc, aluminum silicate, titanium oxide, iron oxide,
Examples thereof include inorganic pigments such as yellow lead, cadmium oxide, carbon black, and aluminum powder, and organic pigments such as permanent red, watching red, phthalocyanine green, phthalocyaning blue, quinacdrine-based, and isoindoline-based. Further, an antifoaming agent, a leveling agent, etc., which are usually blended in a paint, are appropriately used. The clear paint and the colored paint are applied by a usual application method such as brush, spray, roller and the like.

[Operation] The coating composition of the present invention is useful as a coating for interior and exterior coating of buildings.

[Example] Next, the composition of the present invention will be described more specifically with reference to examples. Unless otherwise specified, “%” and “part” are based on weight.

Example 1 In a four-necked flask equipped with a condenser, a stirrer and a thermometer, 140 parts of ethyl acetate, 4 parts of t-butylperoxyisopropyl fumarate and 2,2'-azobis (2,4-dimethylvaleronitrile) 0.6 Then, after bubbling nitrogen, the temperature was raised to 70 ° C.

In the first stage reaction, a mixture of 158 parts of butyl acrylate, 42 parts of methyl methacrylate and 4 parts of t-butyl peroxyisopropyl fumarate was bubbled with nitrogen and then added dropwise for 1.5 hours.

After 2.5 hours, 2,2'-azobis (2,4
-Dimethylvaleronitrile) (0.4 parts) was dissolved and the reaction was continued for 2.5 hours.

Next, in the second reaction, 150 parts of toluene was charged and the temperature was raised. When the internal temperature reached 85 ° C, butyl acrylate 53
Parts, methyl methacrylate 107 parts and styrene 40 parts were bubbled with nitrogen and then added dropwise over 1 hour. Inner temperature is 90
The temperature is controlled to ˜95 ° C., 0.4 parts of azobisisobutyronitrile / 50 parts of toluene is charged at 3 hours, and the reaction is continued for another 2 hours to obtain a resin solution containing a graft copolymer having a glass transition temperature of 0 ° C. (A-1 ) Got.

Control Example 1 A four-necked flask equipped with a condenser, a stirrer and a thermometer was used for 149 parts of methyl methacrylate and butyl acrylate 211.
Parts, 40 parts of styrene and 500 parts of toluene, 1 part of benzoyl peroxide, and after bubbling nitrogen, 90 to 95
Reaction at ℃, 4 parts of benzoyl peroxide 4 parts
After dividing and charging additionally, the reaction was continued for about 10 hours.

A resin solution (B-1) containing a random copolymer having a glass transition temperature of 0 ° C. was obtained.

Example 2 In Example 1, the first reaction was butyl acrylate 14
0 part, methyl methacrylate 30 parts, butyl methacrylate 30
And the second reaction is 2-ethylhexyl acrylate.
A resin solution (A-2) containing a graft copolymer having a glass transition temperature of 5 ° C. was obtained in the same manner as in Example 1 except that 40 parts, 120 parts of methyl methacrylate and 40 parts of styrene were used.

Example 3 In a four-necked flask equipped with a condenser, a stirrer and a thermometer, 140 parts of ethyl acetate, 8 parts of t-butylperoxyallyl carbonate, 0.6 part of 2,2'-azobis (2,4-dimethylvaleronitrile). After charging and bubbling nitrogen 70
The temperature was raised to ° C. The reaction in the first step was carried out with 130 parts of 2-ethylhexyl acrylate, 30 parts of butyl methacrylate and 40 parts of methyl methacrylate, and further 3 parts of benzoyl peroxide were divided into 4 parts and then charged for about 10 hours. Continued. A mixture of 4 parts of t-butyl peroxyallyl carbonate was bubbled with nitrogen and then added dropwise over 1.5 hours.

After 2.5 hours, 2,2'-azobis (2,4
-Dimethylvaleronitrile) (0.4 parts) was dissolved and the reaction was continued for 2.5 hours.

Next, in the second reaction, 150 parts of toluene was charged and the temperature was raised, and when the internal temperature reached 85 ° C., 42 parts of 2-ethylhexyl acrylate, 118 parts of methyl methacrylate, 40 parts of styrene.
Part of the mixture was bubbled with nitrogen and then added dropwise over 1 hour.
The internal temperature was controlled at 90 to 95 ° C, 0.4 part of azobisisobutyronitrile / 50 parts of toluene was charged at the 3rd hour, and the resin was further reacted for 2 hours to contain a graft copolymer having a glass transition temperature of -2 ° C. A solution (A-3) was obtained.

Example 4 In a four-necked flask equipped with a condenser, a stirrer and a thermometer, 140 parts of ethyl acetate, 4 parts of t-butylperoxymethacryloyloxyethyl carbonate, 2,2'-azobis (2.4-dimethylvaleronitrile) 0.6 Then, after bubbling nitrogen, the temperature was raised to 70 ° C. The first reaction is 100 parts of 2-ethylhexyl acrylate and 6 parts of methyl methacrylate.
A mixture of 0 parts, 40 parts of butyl methacrylate, and 4 parts of t-butyl peroxymethacryloyloxyethyl carbonate was bubbled with nitrogen and then added dropwise for 1.5 hours.

After 2.5 hours, 2,2'-azobis (2.4
-Dimethylvaleronitrile) (0.4 parts) was dissolved and the reaction was continued for 2.5 hours.

Next, in the second reaction, 150 parts of toluene was charged and the temperature was raised, and when the internal temperature reached 85 ° C, 40 parts of 2-ethylhexyl acrylate, 100 parts of methyl methacrylate, 60 parts of styrene.
Part of the mixture was bubbled with nitrogen and then added dropwise over 1 hour.
The internal temperature was controlled at 105-110 ° C, and at the third hour, 0.4 parts of azobisisobutyronitrile / 50 parts of xylene were charged,
The reaction was further continued for 2 hours to obtain a resin solution (A-4) containing a graft copolymer having a glass transition temperature of 11 ° C.

[Measurement of physical properties of coating film]

⊚ Clear Film Properties Resin solutions (A-1) to (A-4) and (B-1) were cast to a coating thickness of about 100 μm and dried to prepare a resin film sample. With respect to the obtained film sample, surface tackiness (20 ° C. × 65% RH atmosphere) and film elongation at 0 ° C. and −10 ° C. were measured. The results are shown in Table 1.

◎ White paint film characteristics Titanium oxide is mixed in a predetermined amount with resin solutions (A-1) to (A-4) and the pigment concentration is adjusted to 40 with a paint conditioner.
% White paint was obtained. The obtained white paint was cast and then dried to obtain a white paint film sample. The surface tackiness and film elongation at 0 ° C and -10 ° C of each sample were measured. Table 2 shows the results.

[Effect] According to the present invention, it is possible to obtain a film that is highly flexible even at low temperatures and has no surface tackiness at room temperature. It is used for coating the interior and exterior of buildings, and particularly has a film state capable of sufficiently following cracks in concrete, mortar, and the like.

Claims (2)

(57) [Claims] 1. A copolymer obtained by polymerizing an acrylic monomer and at least one of the following polymerizable peroxides (I), (II) and (III) at a temperature below the decomposition temperature of the peroxide. A coating composition comprising a graft copolymer having a glass transition temperature of -5 to 15 ° C obtained by graft-polymerizing an acrylic monomer at a temperature not lower than the decomposition temperature of the peroxide. However, an integer of n = 1 to 2 R ₁ = hydrogen atom or alkyl group having 1 to ₂ carbon atoms R ₂ = straight chain alkyl group or branched alkyl group having 1 to 9 carbon atoms, phenyl group, or 1 to 3 carbon atoms Alkyl group, substituted phenyl group R ₃ = hydrogen atom or alkyl group having 1 to 4 carbon atoms R ₄ = alkyl group having 1 to 4 carbon atoms R ₅ = alkyl group having 1 to 4 carbon atoms R ₆ = C 1 to carbon number A 12-alkyl group or a C3-C12 cycloalkyl group is shown. 2. The coating composition according to claim 1, wherein the polymerizable peroxide is t-butylperoxyisopropyl fumarate.