JP2001089536A - Alkoxysilane group-containing copolymer and defoaming agent for coating material comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an alkoxysilane group-containing copolymer used as a defoaming agent of a coating material excellent in water resistance of a coating film and good in defoaming properties. SOLUTION: This alkoxysilane group-containing copolymer is a copolymer prepared by copolymerizing 3-70 pts.wt. of an alkoxysilane monomer having vinyl group or (meth)acryloyl group with 30-97 pts.wt. of a monomer having the vinyl group or (meth)acryloyl group and having 2,000-100,000 number-average molecular weight. The alkoxysilane monomer having the vinyl group or (meth) acryloyl group is at least one kind selected from vinyldialkoxysilanes, vinyltrialkoxysilanes, (meth)acryloxydialkoxysilanes and (meth) acryloxytrialkoxysilanes. The monomer having the vinyl group or (meth)acryloyl group is at least one kind selected from (meth)acrylic acid, alkyl (meth)acrylates, cycloalkyl (meth)acrylates, styrene and alkyl vinyl ethers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkoxysilane group-containing copolymer used as an antifoaming agent to be incorporated into a coating material.

[0002]

2. Description of the Related Art By coating a coating material on the outer wall of a building, or the surface of an industrial product such as a building material or an electric home appliance to form a coating, the appearance is improved, and the corrosion resistance and weather resistance are improved. I have. When coating with a non-aqueous coating material such as a baking paint, the surface of the coating film that is being formed by curing the air dissolved or entrained in the coating material or the gas volatilized by the solvent in the coating material When foaming is caused by, foam marks called armpits are generated. Armpits are more likely to occur as the coating film is thicker, and deteriorate the appearance of the painted surface or cause pinholes to lower the corrosion resistance.

[0003] Therefore, an antifoaming agent is blended in the coating material. As an antifoaming agent, for example, Japanese Patent No. 1845067
No. 6: modified butadiene polymer, JP-A-61-1417.
No. 72 discloses an acrylic / vinyl ether copolymer, JP-A-2-232271 discloses a vinyl ether polymer, and JP-A-5-247161 discloses an olefin cooligomer. Conventional defoamers have poor compatibility with coating materials, poor water resistance of the coating film, and insufficient defoaming properties. Had.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has excellent water resistance of a coating film.
An object of the present invention is to provide an alkoxysilane group-containing copolymer which has good defoaming properties and is used as an antifoaming agent for a coating material.

[0005]

The alkoxysilane group-containing copolymer of the present invention, which has been made to achieve the above object, comprises an alkoxysilane monomer having a vinyl group or a (meth) acryloyl group of 3 to 70%. Parts by weight and a monomer having a vinyl group or a (meth) acryloyl group 30 to 97
Number average molecular weight of 2,000 to 100,
000 copolymers. When the amount of the alkoxysilane monomer is less than 3 parts by weight, the compatibility with the coating material is deteriorated, and the water resistance of the formed coating film is deteriorated. If it exceeds 70 parts by weight, the defoaming properties of the coating material will be insufficient.

The alkoxysilane monomer having a vinyl group or a (meth) acryloyl group is selected from vinyl dialkoxy silane, vinyl trialkoxy silane, (meth) acryloxy dialkoxy silane, and (meth) acryloxy trialkoxy silane. Preferably, at least one type is used. The alkoxysilane of the alkoxysilane monomer can be suitably implemented by having 1 to 6 carbon atoms. Examples of such a vinyl dialkoxysilane include N, N-dimethylaminovinyldiethoxysilane and phenylvinyldimethoxysilane. As the vinyl trialkoxysilane, for example,
Examples include vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, vinyltriphenoxysilane, vinyltris (tri-s-butoxysiloxanyl) silane, and vinyltris (2-methoxyethoxy) silane. Examples of the (meth) acryloxydialkoxysilane include (meth) acryloxyalkyldialkoxysilanes such as 3-methacryloxypropylmethyldiethoxysilane and 3-acryloxypropylmethyldimethoxysilane. Examples of the (meth) acryloxy trialkoxysilane include (meth) acryloxyalkyl trialkoxysilanes such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-methacryloxypropyltripropoxysilane. Can be (Meta)
Acryloxyalkyl dialkoxysilane or (meth) acryloxyalkyl trialkoxysilane is more preferable because of easy copolymerization.

The monomer having a vinyl group or a (meth) acryloyl group is at least one selected from (meth) acrylic acid, alkyl (meth) acrylate, cycloalkyl (meth) acrylate, styrene and alkyl vinyl ether. Is preferred.

As the alkyl (meth) acrylate,
Alkyl (meth) having an alkyl group having 4 to 22 carbon atoms
Acrylates such as n-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate , Behenyl (meth) acrylate, benzyl (meth)
Acrylates are mentioned. Examples of the cycloalkyl (meth) acrylate include cyclohexyl (meth) acrylate and isobornyl (meth) acrylate. Alkyl vinyl ethers have 4 to 4 carbon atoms.
Alkyl vinyl ethers having 22 alkyl groups, such as isobutyl vinyl ether, 2-ethylhexyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, myristyl vinyl ether, cetyl vinyl ether, and cyclohexyl vinyl ether.
The mixing ratio of the alkyl vinyl ether is limited to 50 mol% or less based on the monomer having a vinyl group or a (meth) acryloyl group from the viewpoint of reactivity in radical polymerization.

When the number average molecular weight of the alkoxysilane group-containing copolymer is out of the range of 2,000 to 100,000, the defoaming property is reduced. 3,000-40,000
Is more preferably in the range. In order to adjust the molecular weight to the above range, a polymerization regulator such as octyl mercaptan, lauryl mercaptan, mercaptoethanol, thioglycolic acid, β-mercaptopropionic acid, and thioglycerol can be used.

The alkoxysilane group-containing copolymer comprises at least one kind of an alkoxysilane monomer having a vinyl group or a (meth) acryloyl group and at least one kind of a monomer having a vinyl group or a (meth) acryloyl group. Is radically polymerized, for example, in a suitable inert solvent in the presence of a polymerization initiator at 80 to 140 ° C., preferably 90 to 120 ° C., for 2 to 15 hours, preferably 3 to 7 hours. To obtain a copolymer.

The copolymerization can be carried out in a homogeneous system such as solution polymerization, suspension polymerization and emulsion polymerization, but is preferably carried out by solution polymerization.

It is preferable to use an inert solvent which dissolves the produced copolymer and the coating material to be used and has a boiling point near the polymerization temperature. Examples of such solvents include toluene, xylene, aromatic solvents such as Solvesso 100, aliphatic solvents such as mineral spirits, alcohol solvents such as n-butanol and cyclohexanol, and methyl isobutyl ketone. Ketone solvents, butyl acetate exemplified ester solvents, butyl cellosolve, ethyl cellosolve exemplified cellosolve solvents, propylene glycol monomethyl ether exemplified propylene glycol based solvents, ethylene glycol monoethyl ether acetate exemplified. And propylene glycol monoalkyl ether acetate solvents such as propylene glycol monomethyl ether acetate. This inert solvent may be used alone or as a mixture of a plurality of solvents.

Examples of the polymerization initiator include radical initiators such as azo compounds such as azobisisobutyronitrile and dimethylazobisisobutyrate, and organic peroxides such as lauroyl peroxide and diisopropylbenzene hydroperoxide. Oxides.

The antifoaming agent for a coating material of the present invention contains an alkoxysilane group-containing copolymer. This defoaming agent has good compatibility with the coating material and excellent defoaming properties, and can be blended with various paint pigments.
A coating film formed by applying a coating material containing this defoamer does not impair water resistance.

[0015]

Embodiments of the present invention will be described below in detail. Examples 1 to 3 are examples in which an alkoxysilane group-containing copolymer to which the present invention is applied is synthesized, Comparative Examples 1 to 2 are examples in which a copolymer in which the present invention is not applied, and Comparative Examples 3 to 5 are those in which the present invention is synthesized. It is an example of a copolymer which does not apply the invention.

Example 1 100 g of xylene was placed in a 1-liter reaction vessel equipped with a reflux condenser, a thermometer, a nitrogen inlet tube, a stirrer, and a dropping funnel, and heated and stirred while blowing nitrogen gas into the reaction vessel. did. While maintaining the temperature in the reaction vessel at 110 ± 5 ° C., 60.0 g of stearyl methacrylate, 40.0 g of 3-methacryloxypropyltrimethoxysilane, 0.5 azobisisobutyronitrile
g was mixed and uniformly dissolved, and the solution was stirred while dropping over 2 hours. After the dropping, the mixture was stirred at the same temperature for 30 minutes, and then stirred at 120 ° C. for 3 hours.
The solution was cooled to 0 ° C. or lower to obtain a solution of an alkoxysilane group-containing copolymer. The molecular weight distribution of this copolymer was analyzed by a gel permeation chromatography (GPC) analyzer (Showex GPC system manufactured by Showa Denko KK), and as a result, the number average molecular weight was about 30,00.
It was 0.

Example 2 Stearyl methacrylate,
Instead of 3-methacryloxypropyltrimethoxysilane and azobisisobutyronitrile, 4-ethylhexyl methacrylate 40.0 g, lauryl methacrylate 4
A solution of an alkoxysilane group-containing copolymer was obtained in the same manner as in Example 1 except that 0.0 g, 20.0 g of 3-methacryloxypropyltrimethoxysilane, and 0.5 g of lauroyl peroxide were used. This copolymer had a number average molecular weight of about 23,000.

Example 3 Stearyl methacrylate,
Instead of 3-methacryloxypropyltrimethoxysilane and azobisisobutyronitrile, 60.0 g of lauryl methacrylate, 20.0 g of styrene, 20.0 g of 3-methacryloxypropyltrimethoxysilane, 20.0 g of azobisisobutyronitrile. A solution of an alkoxysilane group-containing copolymer was obtained in the same manner as in Example 1 except that 5 g was used. This copolymer has a number average molecular weight of about 20,0.
00.

Comparative Example 1 A copolymer solution was obtained in the same manner as in Example 1 except that 100.0 g of stearyl methacrylate was used and 3-methacryloxypropyltrimethoxysilane was not used. Was. This copolymer had a number average molecular weight of about 32,000.

Comparative Example 2 Stearyl methacrylate,
3-methacryloxypropyltrimethoxysilane, instead of azobisisobutyronitrile, in the same manner as in Example 1 except that 80.0 g of cetyl methacrylate, 20.0 g of styrene, and 0.5 g of lauroyl peroxide were used, A solution of the copolymer was obtained. This copolymer had a number average molecular weight of about 25,000.

Comparative Example 3 An acrylic copolymer (solid content: about 50%) Dispalon OX-60 (trade name, manufactured by Kusumoto Kasei Co., Ltd.) was used as the copolymer.

Comparative Example 4 BYK-354 (BYK Chemie) which is an acrylic copolymer (solid content: about 50%)
Was used as the copolymer.

Comparative Example 5 BYK- which is a special silicon
066 (trade name, manufactured by BYK Chemie) was used as the copolymer.

(Performance Evaluation Test) A coating material was prepared by blending the copolymer solutions obtained in Examples 1 to 3 and Comparative Examples 1 and 2 and the copolymers of Comparative Examples 3 to 5 as defoaming agents. Thereafter, coating was performed, and an evaluation test was performed on the performance of the coated film as follows.

First, Acrydic A-345 (trade name; manufactured by Dainippon Ink), which is an acrylic resin for baking, 1
00.0 g, butylated melamine resin, Super Beckamine L-117-60 (trade name; manufactured by Dainippon Ink and Chemicals, Inc.)
11.5 g, Super Beckamine L-105-60 which is a methylated melamine resin (trade name; manufactured by Dainippon Ink and Chemicals, Inc.)
11.5 g of the mixture was 2,000 milled with a high-speed disper.
The mixture was mixed at 30 rpm for 30 minutes to obtain a paint for performance evaluation test.

Each of the copolymer samples of Examples 1 to 3 and Comparative Examples 1 to 4 was added in an amount of 0.5% to 100 g of the paint for performance evaluation test. The sample of Comparative Example 5 was added at 0.05% to 100 g of the paint for performance evaluation test. These were mixed by stirring at 2000 rpm for 3 minutes using a high-speed disper.
The paint for performance evaluation test containing no copolymer was used as a control.

To each, 40 g of toluene / butanol (weight ratio = 8/2) was added as a diluting solvent, and the mixture was mixed uniformly to prepare a coating material.

The viscosity of the coating material at 25 ° C. was determined according to Ford Cup No. It was measured by four methods. This measuring method is to evaluate the fluidity of a sample by filling a cup of a certain solution with a certain amount of a sample, letting it flow down from a hole having a certain diameter, and measuring the flow time (J.
IS K-5400-4.5.4). The falling time of the coating material solution was about 18 seconds.

The discharge pressure was set to 3.5 k with a diameter of 1.0 mm.
g / cm ² air spray, temperature 25 ° C, humidity 5
Under a 0% condition, an aluminum plate of 20 cm × 30 cm × 0.3 mm was spray-coated so that the film thickness changed stepwise. Immediately after the coating, the coating was baked in a hot air circulating baking furnace at 150 ° C. for 20 minutes to form a cured coating film on the surface of the aluminum plate.

The minimum film thickness at which a wobble occurs, that is, the wobble limit film thickness, was measured for this coating film using an electromagnetic film thickness meter (Ket Scientific Research Laboratory; Kett Electromagnetic Film Thickness Meter LE-200).

Next, the presence or absence of coating film defects other than the wrinkles of the coating film, such as repellency and turbidity, was visually observed.

Further, the aluminum plate was immersed in hot water at 80 to 90 ° C. for 3 hours, allowed to cool, pulled up after the water temperature became 30 ° C. or lower, and dried. As an indicator of water resistance, the presence or absence of water whitening that occurs when the water resistance of the surface of the coating film decreases was visually observed.

Table 1 shows the results of the performance evaluation tests of the coating materials containing the copolymers of Examples 1 to 3 and Comparative Examples 1 to 5 and the coating material containing no copolymer as a control.

[0034]

[Table 1]

As is clear from the table, the coating material containing the copolymer of the present invention as an antifoaming agent has excellent defoaming properties, and the coating film formed by coating has good water resistance.
No cissing is observed on the painted surface. Further, since the limit film thickness of the armpit is large, the occurrence of the armpit can be effectively prevented even if the coating film is thick. A coating film formed by coating a coating material containing a copolymer not applicable to the present invention has poor water resistance.

[0036]

As described in detail above, when the alkoxysilane group-containing copolymer of the present invention is used as a defoaming agent for a coating material, the formed coating film has no surface or cissing on the surface and is resistant to water. Does not inhibit sex.

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Claims (4)

[Claims] 1 to 3 parts by weight of an alkoxysilane monomer having a vinyl group or a (meth) acryloyl group,
A number average molecular weight of 2,000 copolymerized with 30 to 97 parts by weight of a monomer having a vinyl group or a (meth) acryloyl group.
0 to 100,000 alkoxysilane group-containing copolymers. 2. The method according to claim 1, wherein the alkoxysilane monomer having a vinyl group or a (meth) acryloyl group is selected from the group consisting of vinyl dialkoxy silane, vinyl trialkoxy silane, (meth) acryloxy dialkoxy silane, and (meth)
2. The alkoxysilane group-containing copolymer according to claim 1, wherein the copolymer is at least one selected from acryloxy trialkoxysilanes. 3. The method according to claim 1, wherein the monomer having a vinyl group or a (meth) acryloyl group is at least one selected from the group consisting of (meth) acrylic acid, alkyl (meth) acrylate, cycloalkyl (meth) acrylate, styrene, and alkyl vinyl ether. 2. The alkoxysilane group-containing copolymer according to claim 1, wherein the copolymer is of a kind. 4. An antifoaming agent for a coating material, comprising the alkoxysilane group-containing copolymer according to claim 1. Description: