JPH11189701A - Curable composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a two-pack type curable composition suitable as a stain- resistant coating agent or a stain-resistant coating material having properties of being hardly stuck with dust in the atmosphere, stain by rainwater, graffiti, bill, etc. SOLUTION: This curable composition comprises a graft copolymer composed of a unit based on a silicone-based macromonomer as a branch polymer and a vinyl polymer as a truck polymer, containing a hydroxyl group and a carboxyl group in the vinyl polymer and a curing agent. The curing agent is a polyfunctional isocyanate, a block iscoyanate of an amino resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable composition containing a silicone-based graft copolymer as a main component, and the surface of a film formed from the curable composition is resistant to contamination caused by silicone. It has nature. The curable composition of the present invention is suitable as an acid rain paint, a stain resistant coating agent or a stain resistant paint.

[0002]

2. Description of the Related Art Conventionally, paints for buildings, building materials, structures, automobiles, vehicles, electricity, precision equipment, and the like not only impart a beautiful appearance but also have an effect of removing water scale, carbon fine particles, and the like. The property that contaminants are hard to adhere to or can be easily wiped off even if they adhere, or the property that graffiti etc. with oil-based or water-based ink can be easily erased (generally referred to as stain resistance) Is required. Further, in automotive paints and the like, the problem of erosion of the coating film due to acid rain has also become apparent. Conventionally, it has been known to use a polymer containing silicone as one of the typical technical means for imparting stain resistance to a film.

[0003] Among the stain-resistant coating agents or paints using silicone-containing polymers, silicone-based graft copolymers having an alkyl acrylate-based copolymer as a backbone polymer because of their excellent adhesion to substrates. For example, a coating agent comprising a silicone-based graft copolymer obtained by copolymerizing a radical polymerizable silicone macromonomer and an alkyl (meth) acrylate has been widely used (JP-A-61-151272, etc.). .

However, conventional silicone-based graft copolymer coatings still have insufficient stain resistance.
For example, it was not easy to wipe off graffiti or the like written on the film with oil-based ink after a long time without any trace. In addition, when a conventional silicone-based graft copolymer is used for a urethane coating agent, compared to a general-purpose acrylic urethane that does not contain silicone, the time between application of the coating agent solution and the appearance of stain resistance on the coating film is reduced. There was a problem that time was long. If the amount of the curing catalyst, such as an organotin compound, is increased to improve the problem, the pot life of the coating agent, that is, the pot life of the coating agent containing the curing agent is shortened. As means for improving the stain resistance, a graft copolymer using polycaprolactone as a branch polymer in combination with silicone has been proposed (Japanese Patent Laid-Open No. 3-28).
In this case as well, the problem that it takes a long time to completely cure the coating film has not been solved.

On the other hand, the present inventors have proposed a cross-linking method comprising a graft copolymer having a vinyl polymer having a Tg of 40 to 160 ° C. as a branch polymer and a vinyl polymer having a hydroxyl group as a trunk polymer in combination with silicone. The coating film was found to be excellent in both stain resistance and drying property of the coating film, and a patent application was filed for a coating composition containing the graft copolymer as one component (Japanese Patent Application No. Hei 8 (1996) -108). -263
484). In the present invention, it is also an object of the present invention to provide a two-part curable coating agent which is excellent in stain resistance, has a long pot life after mixing two parts, and has a high curing speed of a coating film. .

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by slightly introducing a carboxyl group into a polymer containing a silicone unit and a hydroxyl group, the pot life is reduced. It has been found that the composition is long and can be hardened with an isocyanate or amino resin, and the present invention has been completed. That is, the present invention relates to a graft copolymer comprising a unit based on a silicone-based macromonomer as a branch polymer and a vinyl polymer as a trunk polymer, wherein the vinyl copolymer contains a hydroxyl group and a carboxyl group. A curable composition comprising a coalescable and a curing agent. In a preferred embodiment of the present invention, the ratio of the branch polymer is 0.5 to 30% by weight based on the total amount of the branch polymer and the trunk polymer.
And a carboxyl value (hereinafter referred to as an acid value) of 0.5 to 3
The curable composition using a graft copolymer having 0 KOH mg / g and a hydroxyl value (hereinafter referred to as a hydroxyl value) of 80 to 150 KOH mg / g.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The graft copolymer in the present invention can be synthesized by copolymerizing a silicone-based macromonomer and a vinyl monomer described below, and in this case, among the vinyl monomers, a carboxyl group-containing vinyl monomer And a hydroxyl group-containing vinyl monomer is used as an essential component. The silicone-based macromonomer is a high molecular weight monomer having a radical polymerizable group at one terminal of a silicone molecule represented by polydimethylsiloxane, polydiethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, and the like. Preferred number average molecular weight is 1,000 to 30,000. When the number average molecular weight of the silicone-based macromonomer is less than 1,000, stain resistance, lubricity and water repellency of the coating tend to be insufficient, while when it exceeds 30,000, a transparent graft polymer solution is obtained. hard. As the radical polymerizable group bonded to the terminal of the silicone-based macromonomer, a (meth) acryloyl group or a styryl group is preferable.

[0008] The silicone-based macromonomer can be produced by a known method. For example, a living polymer of dimethylpolysiloxane is synthesized by an anionic polymerization method, and it is combined with a halogenated alkyl (meth) acrylate and an alkyl (meth) acrylate. By the reaction, a silicone-based macromonomer having a (meth) acryloyl group at the terminal is obtained. Further, in an organic solvent such as toluene or xylene, a silanol-terminated compound is added in the presence of an acid catalyst such as p-toluenesulfonic acid. Group-containing polydimethylsiloxane and γ
A similar macromonomer can also be obtained by addition reaction of methacryloxypropyltrimethoxysilane (JP-A-58-167606). A preferable ratio of the branch component based on the silicone-based macromonomer in the graft copolymer is 0.5 to 30% by weight, more preferably 1 to 30% by weight, based on the total amount of all the constituent units of the graft copolymer. 20% by weight. When the ratio of the branch component due to the silicone-based macromonomer is 0.
If the content is less than 5% by weight, the cured film has reduced stain resistance, lubricity, etc., and tends to lack the property of repelling oil-based ink.
If the content exceeds 0% by weight, the hardness of the film is lowered, and contaminants tend to adhere.

Among the vinyl monomers to be copolymerized with the silicone-based macromonomer, a carboxyl group-containing vinyl monomer and a hydroxyl group-containing vinyl monomer are essential as described above. Examples of the carboxyl group-containing vinyl monomer include (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid. The preferred amount of the carboxyl group-containing vinyl monomer is such that the acid value of the obtained graft copolymer is 0.5 to 30K.
OH mg / g. A more preferred acid value of the graft copolymer is 5 to 20 KOHmg / g. If, for example, methacrylic acid is used as the carboxyl group-containing vinyl monomer in order to obtain a graft copolymer having such an acid value, the content of the methacrylic acid monomer unit in the graft copolymer is 0.08 to 4.0. It may be about 6% by weight. The acid value of the graft copolymer is 0.5 KOHmg / g
If the amount is less than 30, when the graft copolymer is used in a urethane coating, the curing reaction of the film is slow, and the time required for developing stain resistance tends to be long. Poor water resistance of the film.

Examples of the hydroxyl group-containing vinyl monomer include hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate. Hydroxyalkyl (meth) acrylate; compound represented by the following formula 1, or commercially available Blenmer PE (Nippon Oil & Fats Co., Ltd., trade name); (meth)
Embedded image which can be synthesized by ring-opening polymerization of ε-caprolactone in the presence of hydroxyethyl acrylate
Or a commercially available product of Praxel F
M or Plaxel FA (all are Daicel Chemical Industries, Ltd., trade names).

[0011]

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[0012]

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The preferred amount of the hydroxyl group-containing vinyl monomer is such that the hydroxyl value of the graft copolymer is 80 to 15;
The amount is 0 KOHmg / g. More preferred hydroxyl value of the graft copolymer is 90 to 140 KOHmg /
g. When the hydroxyl value of the graft copolymer is 80 KOH
When the amount is less than 1 mg / g, the cross-linking density of the obtained cured film is insufficient and the stain resistance tends to be insufficient.
If it exceeds / g, the impact resistance, workability, and adhesion of the cured film are likely to be reduced. When the amount of the hydroxyl group-containing vinyl monomer that gives such a hydroxyl value is expressed in terms of% by weight of the hydroxyl group-containing vinyl monomer unit in the graft copolymer, the amount varies depending on the molecular weight of the hydroxyl group-containing vinyl monomer used. , Usually 1 to 30% by weight. In the present invention, as a hydroxyl group-containing vinyl monomer,
It is preferable to use the compound represented by the above formula 1 or 2 in combination with hydroxyethyl (meth) acrylate. Chemical 1
Alternatively, a graft copolymer having both the compound represented by Chemical Formula 2 and hydroxyethyl (meth) acrylate has excellent reactivity with a curing agent and can form a cured film having a high crosslinking density.

Among the vinyl monomers copolymerized with the silicone macromonomer, monomers other than the above-mentioned carboxyl group-containing vinyl monomer and hydroxyl group-containing vinyl monomer (hereinafter referred to as other vinyl monomers) as,
Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid 2
Alkyl (meth) acrylates such as ethylhexyl, cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; styrene derivatives such as styrene, α-methylstyrene and p-methylstyrene; N
N-alkoxymethyl (meth) acrylamides such as -methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide and N-isobutoxymethyl (meth) acrylamide; (meth) acrylonitrile, γ- (meth) acryloxypropyl Acrylic silane monomers such as trimethoxysilane and γ- (meth) acryloxypropyltriethoxysilane are exemplified.
Further, as a vinyl monomer to be copolymerized with a silicone-based macromonomer, a polyalkyl (meth)
Macromonomers having an acrylate or other vinyl polymer skeleton, such as macromonomer AA-6, AS
-6 or AA-714 [manufactured by Toagosei Co., Ltd.] may be used. The preferred use amount of the other vinyl monomer is about 35 to 98% by weight based on the total amount of all the constituent units in the graft copolymer.

Each of the above-mentioned macromonomers and various monomers is polymerized at a high reaction rate by a solution polymerization method or the like outlined below to obtain a graft copolymer having a constitution substantially corresponding to the charged ratio. Can be That is, polymerization is carried out at 60 to 150 ° C. using a hydrocarbon solvent such as toluene or xylene as a polymerization solvent and a radical generating compound such as azobisisobutyronitrile or benzoyl peroxide as a polymerization initiator. N-
The molecular weight of the obtained graft copolymer may be adjusted by using an appropriate amount of a chain transfer agent such as dodecyl mercaptan, mercaptoacetic acid, thiomalic acid, mercaptoethanol and mercaptopropionic acid. The preferred molecular weight of the graft copolymer is from 8,000 to 4 in terms of weight average molecular weight.
20,000, or 2,000 to 20, in number average molecular weight
000.

The above graft copolymer is usually used as an organic solvent solution. The organic solvent solution of the graft copolymer obtained by solution polymerization can be used as it is as one component of the curable composition.However, the organic solvent is replaced with butyl acetate, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, or the like as necessary. You may. The concentration of the graft copolymer in the organic solvent solution of the graft copolymer is suitably about 30 to 60% by weight.

In the present invention, the curing agent used for curing the above graft copolymer is a compound having a functional group reactive with a hydroxyl group present in the graft copolymer. Examples include polyvalent isocyanate, blocked isocyanate, and amino resin.
Examples of the polyvalent isocyanate include diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate, and isocyanurate type and burette type thereof. Examples of the blocked isocyanate include compounds obtained by blocking a polyisocyanate such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, or xylylene diisocyanate with methyl ethyl ketoxime, acetoxime, ε-caprolactam, diethyl malonate, or the like. The preferred amount of polyvalent isocyanate or blocked isocyanate (hereinafter collectively referred to as polyvalent isocyanate) is a ratio of 0.5 to 1.5 equivalents of isocyanate groups to 1 equivalent of the hydroxyl value in the graft copolymer. As a curing reaction catalyst with polyvalent isocyanate,
An organic tin compound such as dibutyltin dilaurate may be used.

Examples of the amino resin include alkyl etherified melamines such as methyl etherified melamine and butyl etherified melamine; alkyl etherified benzoguanamines such as methyl etherified benzoguanamine and ethyl etherified benzoguanamine; and alkyl etherified urea resins. The preferred use amount of the amino resin is 3 to 80 parts by weight per 100 parts by weight of the graft copolymer.

As described above, the curable composition of the present invention comprises:
Since it forms a stain-resistant film derived from silicone, it is suitable as an acid rain paint, a stain resistant coating agent or a stain resistant paint. Substrates to be coated include metals,
Concrete and plastic etc. are mentioned.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The curable compositions obtained in Examples 1 to 3 and Comparative Example 1 were evaluated for pot life, and formed a film on an aluminum test piece by the method described in Example 1; The following physical properties were evaluated. Also, c), d) and e) below
Was carried out on a coating film left at room temperature for 7 days after film formation. However, with respect to the curable compositions obtained in Examples 4 to 6, after forming a film on the test piece in the same manner,
Using the coating film cured by heating for 30 minutes, the following c),
Tests d), e) and f) were performed.

A) Pot life—The curing agent and the graft copolymer solution were mixed and allowed to stand at room temperature, and the time until the viscosity increased three times or more was measured. B) Oil-resistant ink stainability: After applying the curable composition, the ink was left at room temperature for 20 hours, and the repellency of the ink when marked on the coating film with a red oil-based ink pen was visually evaluated. The results were represented by: when remarkably repelled; 、, when slightly repelled; Δ. C) Hardness of coating film: pencil hardness specified in JIS K 5400. D) Stain resistance 耐 The test piece was immersed in boiling water for 8 hours, and then an oil resistance ink stain test was performed. E) Adhesion: Cross cut test specified in JIS K5400. F) 0.1 ml of an aqueous sulfuric acid solution having a pH of 3 in which kaolin is dispersed at a concentration of 0.2% by weight is dropped onto the coating film. lower limit.

[0022]

Example 1 A graft copolymer (G1) was produced by the method described below using the monomers shown in Table 1 below (units of numerical values in the table are grams). That is,
A glass flask equipped with a stirrer, a reflux condenser, two dropping funnels, a gas inlet tube and a thermometer was charged with AK-32.
0.0 g and 49.8 g of xylene were charged,
The temperature was raised to 140 ° C. Then, from one dropping funnel, A
While the mixed solution of the monomer to be copolymerized with K-32 was dropped over 3 hours, 2,2 ′ was simultaneously added from the other dropping funnel.
-Azobis (2-methylbutyronitrile) (hereinafter ABN)
A polymerization initiator solution obtained by dissolving 0.95 g of xylene in 24.9 g of xylene was added dropwise over 3 hours. Thereafter, 8.8 g of a xylene solution containing 0.47 g of ABN-E was further added.
Was added dropwise over 1 hour, and the reaction was continued for 30 minutes to complete the polymerization.

The obtained graft copolymer (G1) had a weight average molecular weight (weight average molecular weight in terms of polystyrene measured by gel permeation chromatography) of 19,
000, its acid value was 13 (KOHmg / g), and its hydroxyl value was 120 (KOHmg / g). The obtained graft copolymer (G1) xylene solution and polyisocyanate (trade name: Coronate HX manufactured by Nippon Polyurethane Co., Ltd.) were mixed with 1.1 equivalents of isocyanate groups per equivalent of hydroxyl groups in the graft copolymer (G1). Mix in proportions. After further adding dibutyltin dilaurate (30 ppm) to the obtained curable composition, a film having a thickness of 20 μm was formed on an aluminum test plate with a bar coater.
The physical properties of the film were measured, and the results are shown in Table 2.

[0024]

EXAMPLES 2-3 AND COMPARATIVE EXAMPLE 1 In Example 2, a xylene solution of the graft copolymer (G2) was synthesized in the same manner as in Example 1 using the monomers shown in Table 1. In Example 3, a xylene solution of the graft copolymer (G3) was synthesized, and in Comparative Example 1, the graft copolymer (G3) was synthesized.
The xylene solution of 4) was synthesized. The obtained graft copolymer xylene solution and polyisocyanate were mixed in the same manner as in Example 1 to obtain a curable composition. Physical properties of the composition were measured.

[0025]

[Table 1]

The abbreviations for the copolymer components shown in Table 1 are as follows:
Each represents the following compounds. AK-32 polydimethylsiloxane macromonomer having a methacryloyl group at one end of the molecule and having a number average molecular weight of 20,000 [manufactured by Toagosei Co., Ltd.] MAA {methacrylic acid MMA {methyl methacrylate St} << Styrene BA >> Butyl acrylate HEMA >> Hydroxyethyl methacrylate Pharmacel FM1 << Compound represented by the following formula 3 [manufactured by Daicel Chemical Industries, Ltd.]

[0027]

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[0028]

[Table 2]

[0029]

Examples 4 to 6 and Comparative Example 2 Graft copolymer (G1) produced in Examples 1 to 3 and Comparative Example 1
To (G4) and an amino resin (trade name: Cymel 712, manufactured by Mitsui Cytec Co., Ltd.) as a curing agent, to form a coating film as follows. A graft copolymer xylene solution and an amino resin were mixed with a graft copolymer having a solid content of 100.
The amino resin was mixed at a solid content of 25 parts by weight per part by weight. A phosphoric acid-based catalyst was further added to the obtained curable composition for 3 hours.
After adding only 0 ppm, a film having a thickness of 20 μm was formed on an aluminum test plate with a bar coater.
It was baked and cured. The results of measuring the physical properties of the obtained coating film are as shown in Table 3.

[0030]

[Table 3]

[0031]

According to the curable composition of the present invention, a film having silicone units and a high degree of crosslinking can be formed by curing a specific silicone-based graft copolymer with a curing agent. Has excellent stain resistance and acid rain resistance, and is suitable as a paint and a coating agent. Further, the cured film obtained from the curable composition of the present invention is excellent in acid resistance, and thus is useful as an automotive paint in which erosion due to acid rain is regarded as a problem.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 5/16 C09D 5/16 155/00 155/00 161/20 161/20

Claims (3)

[Claims] 1. A graft copolymer comprising a unit based on a silicone-based macromonomer as a branch polymer and a vinyl polymer as a backbone polymer, wherein the vinyl polymer contains a hydroxyl group and a carboxyl group. And a curable composition comprising a curing agent. 2. The curable composition according to claim 1, wherein the curing agent is a polyvalent isocyanate, a blocked isocyanate or an amino resin. 3. The graft copolymer according to claim 1, wherein the proportion of the branch polymer is 0.5% based on the total amount of the branch polymer and the trunk polymer.
-30% by weight, and a carboxyl group value of 0.5-30 KO
Hmg / g and hydroxyl value 80-150K
The curable composition according to claim 1, which is OH mg / g.