JP2953277B2 - Room temperature curable resin composition for coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a room-temperature curable resin composition for coating containing a vinyl copolymer having a silanol group in a side chain, and more particularly to a one-part type cross-linkable resin composition which is crosslinked by moisture in the air. The present invention relates to a room-temperature curable resin composition for coating capable of forming a cured film having excellent weather resistance, flexibility, and adhesion.

[0002]

2. Description of the Related Art Conventionally, acrylurethane-based, acrylsilicone-based, and fluorine-based resins have been used as resins for coatings, especially for use in cold-setting coatings having weather resistance. Etc. are known. Among them, acrylic urethane-based resins are inexpensive, but isocyanate as a raw material is harmful to the human body, and fluorine-based resins have high weather resistance but are expensive. In contrast, demand for acrylic silicone resins has been growing in recent years because the balance between performance and price is moderate.

[0003] This acrylic silicone resin is obtained by bonding an alkoxysilyl group to an acrylic main chain. When applied to a base material, the alkoxysilyl group reacts with moisture in the air at room temperature to form a siloxane bond. Therefore, a stable cured film can be obtained (paint and paint, No.
429, p55-64). As a method for introducing an alkoxysilyl group into the acrylic main chain, a method in which a polymerizable vinyl group-containing silane compound is copolymerized using a radical initiator has been proposed in JP-A-57-36109.

However, the above-mentioned conventional acrylic silicone resins are not provided with properties such as weather resistance and flexibility due to diversification of uses, which are equivalent to fluororesins, and there is a demand for acrylic silicone resins having these properties. Is growing.

[0005] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a room-temperature curable resin composition for coating which has a weather resistance equivalent to that of a fluororesin and can provide a cured film having excellent flexibility.

[0006]

The present inventors have made intensive studies to achieve the above object, and as a result, have found that a polymerizable vinyl monomer and a silanol group-containing (meth) compound represented by the following general formula (2) are obtained. A vinyl copolymer having a silanol group having a unit represented by the following formula (1) in a side chain, which can be obtained by copolymerizing acrylic siloxane with a radical initiator in the presence of a specific initiator described below. Room temperature which is useful for coating which can form a cured film with excellent storage stability and excellent weather resistance, flexibility and adhesion when used in combination with a cross-linking agent and condensation catalyst. It has been found that a curable resin composition can be obtained.

[0007]

Embedded image (Wherein, R ¹ is a hydrogen atom or a methyl group, R ² , R ³ , R
⁴ is a monovalent organic group having 1 to 8 carbon atoms or —OSiR ⁶ R ⁷
A siloxy group represented by R ⁸ , wherein R ⁶ , R ⁷ , and R ⁸ are monovalent organic groups having 1 to ⁸ carbon atoms, R ⁵ is a methyl group, n is an integer of 1 to 12, a Is 0 or 1. )

That is, the above-mentioned room-temperature-curable resin composition is one in which silanol groups are bonded to each other via a crosslinking agent by a moisture (moisture) in the air at room temperature as shown in the following formula to form a three-dimensional structure. Guessed.

[0009]

Embedded image (However, ZX _m is a cross-linking agent, Cat. Is a condensation catalyst, X is a hydrolyzable group, m is 2 or more, and the others have the same meanings as described above.)

On the other hand, a reaction in which silanol groups are directly dehydrated and condensed as shown by the following formula is also conceivable. However, according to the results of studies by the present inventors, a system in which a crosslinking agent is not added does not form a three-dimensional structure. The reason is considered to be due to steric hindrance where a bulky substituent (siloxane) is located near the silanol group.

[0011]

Embedded image (However, Cat. Is a condensation catalyst, X is a hydrolyzable group, m is 2 or more, and the others have the same meaning as described above.)

The vinyl copolymer used in the present invention has a bulky substituent (siloxane) near the crosslinking point in the unit represented by the formula (1) when compared with the conventional acrylic silicone copolymer. , And the steric hindrance protects the crosslinked portion to provide weather resistance. In this case, the copolymer according to the present invention may contain more siloxane bonds than conventional ones. In addition to having excellent weather resistance, the bonding distance of the crosslinked portion is longer by the amount of the crosslinker, and flexibility is imparted due to uneven distribution of siloxane in structure. For this reason, compared with the conventional acrylic silicone type, it is excellent in weather resistance and flexibility, and further,
Since the crosslinking agent also acts as a coupling agent between the cured film and the base material, it has been found that the cross-linking agent has excellent adhesiveness, and the present invention has been accomplished.

Accordingly, the present invention provides a vinyl copolymer containing a silanol group-containing (meth) acrylsiloxane unit represented by the above general formula (1), an alkoxy, acyloxy, oxime of Si, Ti, Al and Zr. And 2 in the molecule selected from amine compounds and their hydrolysates.
Provided is a cold-setting resin composition for coating comprising a crosslinking agent having at least two hydrolyzable groups and a condensation catalyst.

Now, the present invention will be described in more detail. The silanol group-containing vinyl copolymer used in the present invention comprises a polymerizable vinyl monomer and a silanol group-containing (meth) acrylsiloxane represented by the following general formula (2). Is copolymerized in the presence of a radical initiator, so that a unit based on the polymerizable vinyl monomer is used as a main chain, and a unit based on the silanol group-containing (meth) acrylsiloxane of the formula (2) is represented by the following general formula ( The unit of 1) is one obtained by random or block copolymerization.

Here, the polymerizable vinyl monomer is not particularly limited, and methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylate (Meth) acrylic esters such as -2-ethylhexyl, styrenes such as styrene, o-methylstyrene, p-methylstyrene and α-methylstyrene; olefins such as ethylene, propylene, vinyl chloride and vinyl acetate; Alkyl vinyl ethers such as vinyl ether and ethyl vinyl ether; alkyl vinyl ketones such as methyl vinyl ketone and ethyl vinyl ketone; vinyl trimethylsilane; 3- (meth)
Acryloxypropyltrimethylsilane, p-trimethylsilylstyrene, vinyltrimethoxysilane, 3-
(Meth) acryloxypropyltrimethoxysilane, p
Silicon-containing polymerizable monomers such as trimethoxysilylstyrene, vinyltris (trimethylsiloxy) silane, 3- (meth) acryloxypropyltris (trimethylsiloxy) silane, and p-tris (trimethylsiloxy) silylstyrene; And fluorine-containing polymerizable monomers such as 3,3-trifluoropropyl (meth) acrylate and 3,3,3-trifluoro-2-trifluoromethylethyl (meth) acrylate. These polymerizable vinyl monomers may be used alone or in a combination of two or more.

In general, when a polymerizable vinyl monomer is used as a copolymer component, a vinyl copolymer having a polar group is used in combination with the above-mentioned polymerizable vinyl monomer. It is known that the adhesiveness of a film when applied to a resin for coatings is improved. Examples of such a polymerizable vinyl monomer having a polar group include unsaturated organic acids such as (meth) acrylic acid, maleic acid, itaconic acid, citraconic acid, maleic anhydride and itaconic anhydride, and acid anhydrides thereof. , Hydroxyl-containing compounds such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate, and epoxy groups such as glycidyl (meth) acrylate and 2- (3,4-epoxycyclohexyl) ethyl (meth) acrylate Containing compound, 2-
(Diethylamino) ethyl (meth) acrylate, 2-
Amino group-containing compounds such as aminoethyl vinyl ether,
There are N-vinyl-2-pyrrolidone, (meth) acrylamide, acrylonitrile and the like, and in the present invention, one or more of these can be used in combination. However, the compound having a polar group is the moisture (humidity) in the air.
Is introduced into the system, and the storage stability tends to be deteriorated.
%, Particularly preferably 0 to 10% by weight.

On the other hand, the silanol group-containing (meth) acryl siloxane represented by the general formula (2) is as follows, and the unit based on this siloxane is represented by the following general formula (1).

[0018]

Embedded image (Wherein, R ¹ is a hydrogen atom or a methyl group, R ² , R ³ , R
⁴ is a monovalent organic group having 1 to 8 carbon atoms or —OSiR ⁶ R ⁷
A siloxy group represented by R ⁸ , wherein R ⁶ , R ⁷ , and R ⁸ are monovalent organic groups having 1 to ⁸ carbon atoms, R ⁵ is a methyl group, n is an integer of 1 to 12, a Is 0 or 1. )

Here, specific examples of the monovalent organic group having 1 to 8 carbon atoms include an alkyl group such as a methyl group, an ethyl group, a propyl group and a butyl group; a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group; Substituted or unsubstituted aryl groups such as benzyl groups, aralkyl groups such as benzyl groups, alkenyl groups such as vinyl groups and allyl groups, chloromethyl groups, 3,3,3-trifluoropropyl groups and 2-cyanoethyl groups. And a valent hydrocarbon group. Also, -OS
Examples of the siloxy group represented by iR ⁶ R ⁷ R ⁸ include trimethylsiloxy, ethyldimethylsiloxy, phenyldimethylsiloxy, vinyldimethylsiloxy, chloromethyldimethylsiloxy, and 3,3,3-trifluoropropyldimethyl. Examples thereof include a siloxy group and a 2-cyanoethyldimethylsiloxy group. Note that R ^{2 to} R ³ may be the same or different.

The vinyl copolymer used in the present invention contains the unit of the formula (1) as described above, and its content is 1 to 50% by weight, particularly 5 to 20% by weight. Is preferred from the viewpoint of hardness and flexibility.

The molecular weight of the copolymer is 5,000.
Preferably it is ~ 100,000.

As described above, the vinyl copolymer according to the present invention is obtained by copolymerizing a polymerizable vinyl monomer and the silanol group-containing (meth) acrylsiloxane of the formula (2) in the presence of a radical initiator. Although obtained by polymerization, the siloxane of formula (2) can be obtained by a dehydrohalogenation reaction of an organohalosilane and a silanol, followed by a hydrolysis reaction. In this case, it is particularly preferable that n = 3 and a = 0 in the above equation (2).

As the radical initiator used in this reaction, those usually used can be used. Specifically, 2,2′-azobis (isobutyronitrile),
2,2′-azobis (2-methylbutyronitrile),
Azobis compounds such as 2,2′-azobis (2,4-dimethylvaleronitrile), benzoyl peroxide, lauroyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate, etc. Organic peroxides and the like can be used.
These may be used alone or in combination of two or more.

The amount of the radical initiator used is 0.1 with respect to 100 parts (parts by weight, hereinafter the same) of the total amount of the polymerizable vinyl monomer and the silanol group-containing (meth) acrylsiloxane.
It is preferable to set it to 5 parts.

The synthesis of the silanol group-containing vinyl copolymer according to the present invention can be carried out by solution polymerization or bulk polymerization. In the solution polymerization, the polymerizable vinyl monomer and the silanol group-containing (meth) acrylsiloxane of the formula (2) are reacted in a solvent at 50 to 150 ° C. for 3 to 3 hours in the presence of a radical initiator.
It is obtained by reacting for 20 hours. In addition, since bulk polymerization is a polymerization method that does not use a solvent, the viscosity of the obtained copolymer and residual monomers often pose a problem. Therefore, it is preferable to employ a solution polymerization method that uses a solvent.

Examples of the solvent used for the solution polymerization include aliphatic hydrocarbons such as hexane, octane, decane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; and ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, and dioxane. And ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone and cyclohexane, and esters such as methyl acetate, ethyl acetate, butyl acetate and isobutyl acetate. Among them, toluene and / or
Alternatively, it is preferable to use xylene.

In synthesizing the vinyl copolymer according to the present invention, a chain transfer agent may be further added. Specific examples of the chain transfer agent include 2-mercaptoethanol,
Butyl mercaptan, n-dodecyl mercaptan, 3-
Mercapto compounds such as mercaptopropyltrimethoxysilane; and halides such as methylene chloride, chloroform, carbon tetrachloride, butyl bromide, and 3-chloropropyltrimethoxysilane.

In the present invention, silanol group-containing vinyl copolymers having various molecular weights (Mw), molecular weight distributions (Mw / Mn), and glass transition points (Tg) can be obtained according to the application. For example, it is possible to control the molecular weight and molecular weight distribution by appropriately selecting the radical initiator, the solvent, the type of the chain transfer agent, and the amount used, and
By changing the composition of the polymerizable vinyl monomer, a silanol group-containing vinyl copolymer having a desired glass transition point can be obtained.

The cold-setting resin composition of the present invention comprises the above-mentioned vinyl copolymer as a main component and a crosslinking agent and a condensation catalyst.

Here, a crosslinking agent having two or more hydrolyzable groups in one molecule, such as Si, Ti, Al
Alternatively, an alkoxy, acyloxy, oxime or amine compound of Zr or a hydrolyzate thereof is used. Specific examples of such a compound include tetramethoxysilane, tetraethoxysilane, methyltriacetoxysilane, methyltri (ethylmethylketoxime) silane, vinyltri (ethylmethylketoxime) silane, methyltri (n)
Examples thereof include silanes such as (-butylamino) silane and partially hydrolyzed oligomers thereof, and among them, tetramethoxysilane and partially hydrolyzed oligomers thereof are particularly preferably used.

The amount of the crosslinking agent is 1 to 10 parts based on 100 parts of the vinyl copolymer of the present invention.

On the other hand, examples of the condensation catalyst include organic tin compounds such as dibutyltin dilaurate and dibutyltin diacetate, organic titanium compounds such as tetraisopropoxytitanium and tetrabutoxytitanium, 1,4-diazabicyclo (2.2.2) octane, and the like. Amines such as 1,8-diazabicyclo (5.4.0) undecene-7,3- (2-aminoethyl) aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; inorganic acids such as hydrochloric acid and sulfuric acid; Examples thereof include organic acids such as p-toluenesulfonic acid and phthalic acid, and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. Among them, it is particularly preferable to use an organic tin compound. One of these condensation catalysts may be used alone, or two or more thereof may be used in combination.

The mixing amount of the condensation catalyst is 0.01 to 1 part based on 100 parts of the silanol group-containing vinyl copolymer.

When the room temperature curable resin composition of the present invention is crosslinked, crosslinking proceeds even without the addition of a condensation catalyst. However, at room temperature, the crosslinking rate is very slow, and a sufficient crosslinking effect is not exhibited.

Further, various inorganic or organic fillers, pigments and the like can be added to the above-mentioned cold-setting resin composition within the range not impairing the effects of the present invention. Because the composition has excellent compatibility with general-purpose resins,
It can be used by blending with a general-purpose resin.

The form of the cold-setting resin composition of the present invention may be a one-pack type in which all of the above-mentioned components are blended, or a two-pack type in which a condensation catalyst is separated. Here, in the case of the conventional acrylic silicone resin composition, particularly in the case of a one-pack type composition, it has been pointed out that the problem that thickening and gelation occur due to the gradual progress of crosslinking during storage. Since the crosslinking agent acts as a moisture scavenger in the cold-setting resin composition of the present invention, a cold-setting resin composition for coating which is excellent in storage stability even in a one-pack type and is useful as a weather-resistant paint can be obtained.

[0037]

According to the present invention, a cured film excellent in weather resistance, flexibility and adhesion can be formed by blending a vinyl copolymer having a silanol group in a side chain as a main component. A cold-curable resin composition for coating can be provided, and this cold-curable resin composition can provide a cured film having excellent storage stability even when used as a one-pack type, and having excellent weather resistance, flexibility, and adhesion. It can be formed and is useful as a paint for coating.

[0038]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Production Examples, Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Production Examples 1 to 3 and Comparative Production Examples 1 and 2] The inside of a flask equipped with a dropping funnel, a cooler, a thermometer, and a stirring device was purged with nitrogen, and 100 parts of toluene was charged therein.
The temperature was raised to 80 ° C. Next, methyl methacrylate 85
Parts, 7 parts of butyl acrylate, 8 parts of silicone methacrylate (I) shown in Table 1, and 1 part of 2,2′-azobis (isobutyronitrile) were previously mixed and dissolved, and the mixture was dissolved at 80 to 90 ° C. under a nitrogen stream. The solution was dropped into the toluene over 2 hours from the dropping funnel.

Next, after aging at 80 ° C. for 5 hours, the reaction solution was sampled, and the reaction rate was determined from the loss on drying. The result was 99.5%. When the reaction solution was cooled to room temperature, it was colorless. A transparent liquid vinyl copolymer was obtained. When the molecular weight of the obtained copolymer was measured by GPC, it was confirmed that the weight-average molecular weight was 40,000, and a peak of Si-OH was observed by IR measurement, and the presence of a silanol group was confirmed. (Production Example 1).

Using a polymerizable vinyl monomer, silicone methacrylate, a radical initiator and a solvent shown in Table 1, a vinyl copolymer was obtained at a predetermined temperature in the same manner as in Production Example 1.
The weight average molecular weight was measured by GPC, and the presence of silanol was confirmed by IR. These results are also shown in Table 1.

[0042]

[Table 1]

[0043]

Embedded image

Examples 1 to 4 and Comparative Examples 1 to 4 100 parts of a vinyl copolymer shown in Table 2, 5 parts of a crosslinking agent, and 0.2 part of a condensation catalyst were mixed to reduce the nonvolatile content to 25% by weight. The resulting mixture was diluted with toluene to obtain a room temperature curable resin composition. This composition is polished and coated on a steel bar coater (# 36)
Was applied so that the film thickness after drying was about 10 μm, and was allowed to cure at room temperature for 7 days.

This cured film was evaluated for hardness, adhesion, flexibility, solvent resistance and weather resistance by the following methods. Further, the storage stability as a room-temperature-curable resin composition was also evaluated. Hardness The pencil hardness was measured using Mitsubishi Uni pencil. 10 × 10 squares of 1 mm square were formed on the cured adhesive film, and a peeling test was performed using a cellophane tape (Nichiban cellophane tape). A flexible mandrel test (6φ) was performed and judged according to the following criteria. ：: No change in appearance. 微小: Fine cracks generated. X: Cracks were generated and peeling solvent-resistant xylene rubbing was performed 10 times, and the appearance was determined according to the following criteria. ○: No change in surface appearance △: Slight change in surface appearance ×: Change in surface appearance Weatherproof sunshine weatherometer (manufactured by Suga Test Instruments Co., Ltd.)
The appearance after exposure for 300 hours was determined according to the following criteria. ○: No change in surface appearance △: Slight change in surface appearance ×: Change in surface appearance Storage stability The number of days until gelation when the room temperature curable composition is sealed in a container and stored at 40 ° C. Examined.

[0046]

[Table 2]

──────────────────────────────────────────────────続 き Continuing on the front page (72) Nobuyuki Suzuki 1-10 Hitomi, Matsuida-machi, Usui-gun, Gunma Prefecture Inside Silicone Electronics Materials Research Laboratory Shin-Etsu Chemical Co., Ltd. (72) Inventor Shoji Ichinohe Usui-gun, Gunma Prefecture No. 1 Hitomi, Matsuidamachi Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (56) References JP-A-61-118451 (JP, A) JP-A-59-81320 (JP, A) 2-140718 (JP, A) JP-A-6-289333 (JP, A) U.S. Pat. No. 4,419,505 (US, A) WO 93/12162 (WO, A1) WO 86/4343 (WO, A1) (58) Surveyed field (Int. Cl. ⁶ , DB name) C09D 143/03 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] (A) The following general formula (1): (Wherein, R ¹ is a hydrogen atom or a methyl group, R ² , R ³ , R
⁴ is a monovalent organic group having 1 to 8 carbon atoms or —OSiR ⁶ R ⁷
A siloxy group represented by R ⁸ , wherein R ⁶ , R ⁷ , and R ⁸ are monovalent organic groups having 1 to ⁸ carbon atoms, R ⁵ is a methyl group, n is an integer of 1 to 12, a Is 0 or 1. 100 parts by weight of a vinyl copolymer having a silanol group in a side chain containing a silanol group-containing (meth) acrylsiloxane unit represented by the formula): (B) alkoxy, acyloxy, oxime and amine of Si, Ti, Al and Zr A compound and a cross-linking agent having two or more hydrolyzable groups in a molecule selected from the hydrolyzate thereof, in an amount of 1 to 10 parts by weight, and (C) a condensation catalyst in an amount of 0.01 to 1 part by weight. Room temperature curable resin composition for coating.