JP2000034440A - Staining-resistant coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating agent which can form a coating film excellent in staining resistance and water washability by compounding a multi-branched polymer composed of a hydroxyl-containing vinyl polymer having side chains bonded thereto and comprising a polymer unit comprising polyalkylene glycol units and polyorganosiloxane units and a curing agent. SOLUTION: This agent comprises 100 pts.wt. multi-branched polymer obtained by copolymerizing a macromonomer having as a skeletone a polymer comprising both of polyalkylene glycol units [e.g. polyalkylene glycol mono(meth)acrylate] and polyorganosiloxane units and having a radically polymerizable group at one terminal with a hydroxyl-containing vinyl monomer such as 2-hydroxyalkyl(meth)acrylate and other radically polymerizable monomers such as (meth)acrylic acid, and 3-80 pts.wt. curing agent such as an amino resin. The multi-branched polymer has a hydroxyl value of 60-150 mgKOH/g, a weight-average molecular weight of 8,000-40,000, and a number- average molecular weight of 4,000-20,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stain-resistant coating agent, and a polymer which is a main component of the coating agent of the present invention is a polyorganosiloxane unit having excellent stain resistance and having excellent water-cleaning properties. It has both polyalkylene glycol units as constituent units.

[0002]

2. Description of the Related Art Conventionally, paints for buildings, building materials, structures, automobiles, vehicles, electricity, precision equipment, etc., have been required to not only impart beautiful appearance but also to have the following stain resistance. Have been. That is, a property that a contaminant such as carbon fine particles and scale is difficult to adhere to or is easily wiped off even if it adheres, or a property such as graffiti with an oily or water-based ink that can be easily erased is generally used. Is referred to as stain resistance. Conventionally, it has been known to use a polymer containing silicone as one of the typical technical means for imparting stain resistance to a coating film.

[0003] Among coating agents or paints using a silicone-containing polymer, silicone-based graft copolymers having an alkyl acrylate-based copolymer as a trunk polymer, such as radicals, because of their excellent adhesion to substrates. Many coating agents comprising a silicone-based graft copolymer obtained by copolymerizing a polymerizable silicone macromonomer and an alkyl (meth) acrylate have been used (JP-A-61-151272, JP-A-3-151272). 281516
No.).

[0004] However, the conventional coating film made of the silicone-based graft copolymer has insufficient stain resistance. For example, the adhesion of stains by organic substances such as carbon and graffiti written on the coating film with oil-based ink are difficult. After a long time, it has been difficult to wipe it off without any trace and to wash it with water. In order to solve the above problems, the present inventors have created an invention in which a graft polymer having silicone as a branch polymer and a vinyl polymer containing a hydroxyl group as a trunk polymer is cured with a polyvalent isocyanate. (Japanese Patent Application No. 9-304844).
However, the coating film obtained by the above-mentioned invention has insufficient hydrophilicity, so that when the dirt attached to the coating film is removed by washing with water, the dirt is easily removed (hereinafter referred to as water washability). It was a step.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have completed the present invention. That is, the present invention provides (A) a hyperbranched polymer in which a polymer unit having both a polyalkylene glycol unit and a polyorganosiloxane unit is bonded as a side chain of a vinyl polymer chain having a hydroxyl group; It is a stain-resistant coating agent comprising a curing agent reactive with hydroxyl groups. Hereinafter, the present invention will be described in more detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The hyperbranched polymer according to the present invention comprises a radical polymerizable macromonomer having a skeleton of a polymer having both a polyalkylene glycol unit and a polyorganosiloxane unit, a hydroxyl group-containing vinyl monomer and It can be produced by copolymerizing other radically polymerizable monomers. First, the radical polymerizable macromonomer having the above specific structure (hereinafter referred to as the present macromonomer) will be described. As a method for producing the macromonomer of the present invention, a method generally used in the production of a conventionally known radically polymerizable macromonomer can be used, and the outline thereof is as follows. That is, a radical polymerizable monomer having a polyalkylene glycol skeleton described below (hereinafter referred to as a polyalkylene glycol monomer) is obtained by radical polymerization using a mercapto compound having a carboxyl group such as mercaptopropionic acid as a chain transfer agent. And after copolymerizing a polyorganosiloxane having a radical polymerizable group (hereinafter referred to as a silicone macromonomer), by reacting the resulting carboxyl group-containing polymer with glycidyl methacrylate or the like, a type having a methacryloyl group at one end. The macromonomer of the present invention is obtained. As the radical polymerizable group that the macromonomer of the present invention has at the molecular terminal, a (meth) acryloyl group and a styryl group are preferable.

The polyalkylene glycol-based monomer in the present invention is used for introducing a polyalkylene glycol unit into the macromonomer of the present invention, and is typically, for example, polyalkylene glycol mono (meth) acrylate or polyalkylene glycol. Monoalkyl ether mono (meth) acrylate and the like can be mentioned. Examples of the polyalkylene glycol mono (meth) acrylate include polyethylene glycol mono (meth) acrylate and polypropylene glycol mono (meth) acrylate. Also, polyalkylene glycol monoalkyl ether mono (meth) acrylate)
Examples of the acrylate include methoxy polyethylene glycol mono (meth) acrylate, ethoxy polyethylene glycol mono (meth) acrylate, butoxy polypropylene glycol mono (meth) acrylate, and methoxy polyethylene glycol polypropylene glycol mono (meth) acrylate. In addition to the above compounds, methoxypolytetramethylene glycol polyethylene glycol mono (meth) acrylate, benzyloxy polyethylene glycol (meth) acrylate, and the like can be used as the polyalkylene glycol-based monomer.

The preferred degree of condensation of the alkylene oxide repeating unit in the polyalkylene glycol monomer is 2 to 50, more preferably 3 to 30. When the condensation degree of the alkylene oxide repeating unit is 50
If it exceeds 300, the water resistance of the film formed from the obtained hyperbranched polymer tends to decrease. The preferred number of carbon atoms of the alkylene in the alkylene oxide unit forming the polyalkylene glycol-based monomer is 2 or 3, and particularly preferably 2.

The silicone macromonomer includes:
A macromonomer in which a radical polymerizable group such as a (meth) acryloyl group is bonded to one end of a molecule of a polyorganosiloxane represented by polydimethylsiloxane, polydiethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, etc. . The preferred number average molecular weight of the silicone macromonomer is 500 to 1
It is 0000. If the number average molecular weight of the silicone macromonomer is less than 500, stain resistance of the coating film tends to be insufficient, while if it exceeds 10,000, it is difficult to obtain a transparent multi-branched polymer solution.

In the macromonomer of the present invention, the preferable content ratio of the polyalkylene glycol unit and the polyorganosiloxane unit is 5 to 95% by weight of the polyalkylene glycol unit and 9% by weight of the polyorganosiloxane unit.
5 to 5% by weight. When the proportion of the polyorganosiloxane unit is less than 5% by weight, it is difficult to concentrate the macromonomer unit of the present invention on the surface of the coating film in the obtained multibranched polymer, so that the stain resistance tends to decrease. If it exceeds, the water washability of the coating film is liable to be impaired. As a component constituting the polymer portion in the macromonomer of the present invention, a component other than the above polyalkylene glycol unit and polyorganosiloxane unit, for example, a (meth) acrylate unit, a vinyl carboxylate unit, a (meth) acrylonitrile unit or a styrene unit May be included to such an extent that the effects of the present invention are not impaired. The preferred number average molecular weight of the macromonomer of the present invention is from 1,000 to 10,000.
00. When the number average molecular weight of the macromonomer is
If it is less than 0, the property of repelling oil ink and the like tends to be insufficient,
On the other hand, if it exceeds 10,000, the hardness of the coating film decreases, and dirt easily adheres.

The preferred content of the macromonomer unit of the present invention in the hyperbranched polymer is 0.5 to 30% by weight, more preferably 1 to 30% by weight, based on the total amount of all the structural units of the hyperbranched polymer. -20% by weight. If the proportion of the macromonomer unit is less than 0.5% by weight, the cured coating film formed from the hyperbranched polymer and the curing agent tends to be insufficient in the property of repelling contaminants and oil-based ink.
If the content is more than 10% by weight, the hardness of the coating film decreases, and contaminants easily adhere.

As described above, the monomers to be copolymerized with the macromonomer of the present invention to obtain the hyperbranched polymer in the present invention are a hydroxyl group-containing vinyl monomer and other radically polymerizable monomers. . Examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Of hydroxyalkyl (meth) acrylate, and
A compound represented by the following formula 2, which can be synthesized by ring-opening polymerization of ε-caprolactone in the presence of hydroxyethyl (meth) acrylate: For example, Praxel FM or Praxel FA (both manufactured by Daicel Chemical Industries, Ltd.); a compound represented by the following formula 3, which can be synthesized by adding hydroxyalkyl methacrylate and neopentyl glycol carbonate,
For example, Praxel HEMAC [Daicel Chemical Industries, Ltd.
Manufactured).

[0013]

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[0014]

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[0015]

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The preferred amount of the hydroxyl group-containing vinyl monomer is such that the hydroxyl value of the hyperbranched polymer is 60 to 150K.
The amount is OH mg / g, and more preferably the amount is 80 to 140 KOH mg / g in terms of the hydroxyl value of the polymer. The hydroxyl value of the hyperbranched polymer is 60 KOHmg /
When the amount is less than 0.1 g, the crosslinked density of the obtained cured coating film is insufficient and the stain resistance is apt to be insufficient. On the other hand, when it exceeds 150 KOHmg / g, the impact resistance, processability and adhesion of the cured coating film are liable to decrease.

Other radically polymerizable monomers used together with the hydroxyl group-containing vinyl monomer include ethylenically unsaturated carboxylic acids such as (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride and itaconic acid. Acid; (meth) such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate
Alkyl acrylate; styrene derivatives such as styrene, α-methylstyrene and p-methylstyrene;
N-alkoxymethyl (meth) acrylamides such as N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide and N-isobutoxymethyl (meth) acrylamide; (meth) acrylonitrile, γ- (meth) acryloxy Acrylic silane monomers such as propyltrimethoxysilane and γ- (meth) acryloxypropyltriethoxysilane are exemplified. These can be used alone or in combination of two or more. Further, a macromonomer AA-6,
AS-6 or AA-714 (manufactured by Toagosei Co., Ltd.) may be used.

In the present invention, in order to improve the reactivity between the hyperbranched polymer and the curing agent, it is preferable that the hyperbranched polymer contains a carboxyl group. It is preferred to use ethylenically unsaturated carboxylic acids as part of the body. The preferred acid value in the hyperbranched polymer is 0.5 to 30 KOHmg /
g, more preferably 5 to 20 KOH mg / g.
It is. The acid value of the hyperbranched polymer is 0.5 KOHmg / g
When the amount is less than the above, when the hyperbranched polymer is baked and cured with an amino resin, the time until the coating film is sufficiently cured becomes longer. On the other hand, when it exceeds 30 KOHmg / g, the water resistance of the obtained coating film is inferior. .

The macromonomer of the present invention and the above-mentioned monomer are polymerized at a high reaction rate by a solution polymerization method or the like outlined below to obtain a hyperbranched polymer having a structure corresponding to the charge ratio. . That is, using a hydrocarbon solvent such as toluene and xylene as a polymerization solvent, and using a radical generating compound such as azobisisobutyronitrile and benzoyl peroxide as a polymerization initiator,
Polymerize at 150 ° C. If necessary, a suitable amount of a chain transfer agent such as n-dodecyl mercaptan, mercaptoacetic acid, thiomalic acid, mercaptoethanol and mercaptopropionic acid may be used to adjust the molecular weight of the resulting multibranched polymer. The preferred molecular weight of the hyperbranched polymer is 8,000 to 40,000 in weight average molecular weight, or 4,000 to 20,000 in number average molecular weight.

The organic solvent solution of the hyperbranched polymer obtained by the above solution polymerization can be used as it is as one component of the curable composition, but if necessary, the solvent may be of another kind, for example, butyl acetate, methyl isobutyl ketone. Alternatively, it may be replaced with propylene glycol monomethyl ether acetate or the like. The concentration of the hyperbranched polymer in the organic solvent solution of the hyperbranched polymer is suitably about 30 to 60% by weight.

Next, a curing agent used for curing the above-mentioned multibranched polymer will be described. As the curing agent in the present invention, an isocyanate-based curing agent and an amino resin can be used. As the isocyanate-based curing agent, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate,
Any of polyisocyanate compounds such as xylylene diisocyanate and compounds obtained by further blocking them with methyl ethyl ketoxime, acetoxime, ε-caprolactam, diethyl malonate or the like depending on the curing conditions can be used. The amount of the isocyanate used is about equivalent to 1.1 times equivalent to the hydroxyl value in the polymer.

Examples of the amino resin include alkyl etherified melamine such as methyl etherified melamine and butyl etherified melamine, alkyl etherified urea resin, and alkyl etherified benzoguanamine such as methyl etherified benzoguanamine and ethyl etherified benzoguanamine. The preferred amount of the amino resin used is 3 to 80 parts by weight (amino resin solid content) per 100 parts by weight of the copolymer. As described above, the coating agent comprising the hyperbranched polymer and the curing agent forms a stain-resistant coating film derived from the polyorganosiloxane, and thus is suitable as a stain-resistant paint, a weather-resistant paint, and the like. Substrates to be coated include metal, concrete, plastic, and the like.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, the coating agent obtained in each example forms a coating film on an aluminum test piece by the method described in Example 1, and uses a coating film that is heat-cured at 140 ° C. for 30 minutes after the film formation. Physical properties were evaluated. A) Oil resistance ink stainability: After applying the resin composition on a test piece and curing by heating at 140 ° C. for 30 minutes, the repellency of the ink when marked on the coating film with a red oily ink pen is visually evaluated. did. The results were represented by: when remarkably repelled; 、, when slightly repelled; Δ. B) Hardness of coating film: pencil hardness specified in JIS K5400. C) Stain resistance: After the test piece was immersed in boiling water for 8 hours, a stain test was performed with an oil-resistant ink. 2) Adhesion; cross cut test specified in JIS K 5400.

[0024]

Reference Example 1 (Synthesis of Macromonomer A) Toluene 10
A mixture of 0 parts and 1.8 parts of 3-mercaptopropionic acid was heated to 90 ° C. under a nitrogen stream and stirred, and 70 parts of methoxypolyethylene glycol monomethacrylate (average degree of polymerization of ethylene oxide: about 9) was added to the liquid. 30 parts of polydimethylsiloxane having a methacryloyl group at one end (trade name: X-22-174DX; manufactured by Shin-Etsu Chemical Co., Ltd .; number average molecular weight: about 5,000) and 1 part of azobisisobutyronitrile It was dropped over time. By further heating for 2 hours, a polymer having a carboxyl group at one end and having a number average molecular weight of 7,300 was obtained. Glycidyl methacrylate was further added to the toluene solution.
A solution prepared by dissolving 65 parts, 0.9 part of tetrabutylammonium bromide and 0.05 part of hydroquinone monomethyl ether in 10 parts of toluene was added dropwise, and reacted at 110 ° C. for 3 hours while blowing air. Thereafter, the solvent was removed with a spray drier. 101 parts of a solid macromonomer A having a methacryloyl group at one end of a polymer having a methoxypolyethylene glycol monomethacrylate unit ratio of 70% by weight and a polydimethylsiloxane unit ratio of 30% by weight were obtained. GPC
The number average molecular weight in terms of polystyrene by analysis was 7,50.
0 and the weight average molecular weight was 17,100.

[0025]

REFERENCE EXAMPLE 2 (Synthesis of Macromonomer B) A polymer having a composition of 30% by weight of methoxypolyethylene glycol monomethacrylate units and 70% by weight of polydimethylsiloxane units in the same manner as in Reference Example 1. A solid macromonomer B having a methacryloyl group at one end was obtained. The polystyrene equivalent number average molecular weight was 7,700, and the weight average molecular weight was 17,600.

[0026]

Example 1 Using the monomers shown in Table 1 below,
A hyperbranched polymer was produced by the following method. In a glass flask equipped with a stirrer, a reflux condenser, two dropping funnels, a gas inlet tube and a thermometer, macromonomer A; 10.0
g and xylene 49.8 g, and the temperature was raised to 140 ° C. Next, a mixture of monomers was dropped from one dropping funnel over 3 hours, and simultaneously, 2,2′-azobis (2-methylbutyronitrile) was dropped from the other dropping funnel.
0.95 g of xylene (hereinafter referred to as ABN-E)
A polymerization initiator solution dissolved in 9 g was added dropwise over 3 hours. Thereafter, 8.8 g of a xylene solution containing 0.47 g of ABN-E was further added dropwise over 1 hour, and the reaction was continued for 30 minutes to complete the polymerization. The weight average molecular weight of the obtained hyperbranched polymer was 18,000, the acid value was 13 (KOHmg / g), and the hydroxyl value was 120 (KOHmg / g).

The obtained multi-branched polymer xylene solution and Cymel 712 [amino resin manufactured by Mitsui Cytec Co., Ltd.]
Was mixed with 25 parts by weight of an amino resin per 100 parts by weight of the solid content of the hyperbranched polymer. After further adding a phosphoric acid-based catalyst (30 ppm) to the obtained resin composition, a coating film having a thickness of 20 μm was formed on an aluminum test plate with a bar coater, and baked and cured at 140 ° C. for 30 minutes. The physical properties of the obtained coating film were measured, and the results are shown in Table 2.

[0028]

Example 2 and Comparative Example 1 A xylene solution of a hyperbranched polymer was synthesized in the same manner as in Example 1 using the monomers and the like shown in Table 1. The obtained multi-branched polymer xylene solution and amino resin were mixed in the same manner as in Example 1 to obtain a coating composition. Physical properties of the composition were measured.

[0029]

Comparative Example 2 Instead of the macromonomer of the present invention, that is, a macromonomer having both a polyorganosiloxane unit and a polyalkylene glycol unit as a constitutional unit,
Using two kinds of macromonomers, a silicone macromonomer having a polyorganosiloxane skeleton and a polyalkylene glycol monomethacrylate, and otherwise using the same monomers as in Example 1, the multi-branch of the present invention is used. A polymer similar to the polymer was prepared. Hereinafter, the physical properties of the coating composition were evaluated in the same manner as in the above examples, and the results are shown in Table 2. By comparing this Comparative Example 2 with Examples 1 and 2, the polyorganosiloxane unit and the polyalkylene glycol unit are obtained by copolymerizing a macromonomer corresponding to each unit with another monomer, It can be seen that, when introduced into a hyperbranched polymer, unexpectedly, excellent stain resistance cannot be obtained.

The units of the numerical values in Table 1 below are grams, and the monomers represented by symbols and the like are the following compounds, respectively. AK-32: polydimethylsiloxane 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.] PEGMA: methoxypolyethylene glycol monomethacrylate (condensation degree of ethylene oxide: 9) MAA: Methacrylic acid MMA: Methyl methacrylate St: Styrene BA: Butyl acrylate HEMA: Hydroxyethyl methacrylic acid fluxel FM1: Monomer represented by the following formula 4 (manufactured by Daicel Chemical Industries, Ltd.)

[0031]

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[0032]

[Table 1]

[0033]

[Table 2]

[0034]

According to the coating agent of the present invention, a cured film excellent in stain resistance and water washability is formed.

Claims (1)

[Claims] 1. A hyperbranched polymer comprising (A) a polymer unit having a polyalkylene glycol unit and a polyorganosiloxane unit as a side chain of a vinyl polymer chain having a hydroxyl group, and (B) a hydroxyl unit. A stain-resistant coating agent comprising a curing agent having reactivity with a group.