JP2009191257A - Resin composition for coating having abrasion-resistance, and its coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for coating providing a coating excellent in abrasion resistance while keeping appearance and adhesion. <P>SOLUTION: Provided is the resin composition for coating comprising (A) a (meth)acrylic copolymer containing a hydroxy group and (B) a polyisocyanate compound, wherein the (A) comprises (a1) an alkyl(meth)acrylate having a 10-30C alkyl chain, and (a2) a compound having a reactive unsaturated bond excluding (a1). Also provided is the resin composition for coating comprising (a1) the alkyl(meth)acrylate having a 10-30C alkyl chain, and (a2) the compound having a reactive unsaturated bond excluding (a1) in a ratio of (a1)/(a2)=0.5/99.5-20/80 by mass%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coating composition having good appearance and adhesion and excellent wear resistance to metal / plastic materials such as automobile parts and home appliances, and a coating film thereof.

In order to prevent wear and damage to metal and plastic materials such as automobile parts and home appliances, a coating film is formed on these materials to improve durability against wear and damage. Conventionally, in order to improve the wear resistance, a method of blending an additive in order to give the surface slipperiness, a method of increasing the surface hardness of the coating film, and the like have been devised.
For example, a method of mixing colloidal silica (Patent Document 1), a method of improving the wear resistance by mixing a lubricant component such as a fluororesin or a polyolefin wax (Patent Document 2), and a method of increasing the surface Tg (Patent Document 3) and the like improve the wear resistance.
However, the method using these additives and the method of increasing the Tg may deteriorate the appearance or deteriorate the adhesion.

JP 2000-14049 A JP 2004-51725 A Republished report 2004-11564

  An object of the present invention is to provide a coating composition having excellent abrasion resistance while maintaining the appearance and adhesion, and a coating film thereof.

The resin composition for paints having abrasion resistance and the coating film thereof according to the present invention are [1] to [4].
[1] A composition comprising (A) a hydroxyl group-containing (meth) acrylic copolymer and (B) a polyisocyanate compound (B), wherein (A) is an alkyl chain having 10 to 30 carbon atoms in (a1) alkyl chain A resin composition for coatings comprising (meth) acrylate and a compound containing a reactive unsaturated bond other than (a2) and (a1).
[2] The mass% of the (a1) alkyl chain (meth) acrylate having 10 to 30 carbon atoms of the alkyl chain and the compound containing a reactive unsaturated bond other than (a2) and (a1) is (a1) / (A2) = Resin composition for paint according to [1], wherein 0.5 / 99.5 to 20/80.
[3] The coating resin composition according to [1], wherein the weight average molecular weight (Mw) of the (A) hydroxyl group-containing (meth) acrylic copolymer is 10,000 or more.
[4] A coating film comprising the coating resin composition according to [1], wherein the abrasion resistance measured by a taper abrasion test method (JIS K5600-5-9) is 500 times or more.

  With the resin composition for paints of the present invention, it is possible to obtain a coating film having excellent wear resistance while maintaining the appearance and adhesion.

  The present invention will be described in detail below.

[(A) Hydroxyl group-containing (meth) acrylic copolymer]
(A) A hydroxyl group-containing (meth) acrylic copolymer is a compound containing (a1) an alkyl (meth) acrylate having 10 to 30 carbon atoms in the alkyl chain and a reactive unsaturated bond other than (a2) and (a1). Is included.

( A1 ) Alkyl (meth) acrylate having 10 to 30 carbon atoms in alkyl chain (a1) Alkyl (meth) acrylate) acrylate having 10 to 30 carbon atoms in the alkyl chain used in the present invention includes, for example, decyl acrylate and lauryl. Alkyl acrylates such as acrylate, palmityl acrylate, palmityl acrylate, and behenyl acrylate, or corresponding methacrylates. The number of carbon atoms is preferably 14 to 24, and more preferably 16 to 22 in terms of the appearance and abrasion resistance of the coating film. In the present invention, two or more of these may be used.

(A2) (a1) is not particularly restricted compounds containing reactive unsaturation other than reactive unsaturated bond-containing compound (a1) other than, for example, methyl (meth) acrylate, ethyl (Meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (Meth) acrylate and other (meth) acrylic acid esters, and nitrogen-containing reactivity such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and (meth) acrylonitrile Compounds with unsaturated bonds, and functional group-containing reactive unsaturated bonds As a compound having a hydroxyl group-containing reactive unsaturated bond, a hydroxyl group-containing reactive unsaturated bond such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc. As a compound having a carboxyl group-containing reactive unsaturated bond, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, and a compound having a glycidyl group-containing reactive unsaturated bond Includes glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl (meth) acrylate, and the like.
Other than (meth) acrylic acid ester monomers, styrene, α-methylstyrene, vinyltoluene, vinyl acetate, vinyl propionate and the like can be mentioned. Copolymerization is performed using one or more kinds of these compounds having a reactive unsaturated bond.
Moreover, you may copolymerize other radically polymerizable monomers, such as polyfunctional monomers, such as a trimethylol propane tri (meth) acrylate.

  (A1) The mass% ratio of the alkyl (meth) acrylate having 10 to 30 carbon atoms in the alkyl chain and the compound containing a reactive unsaturated bond other than (a2) and (a1) is the appearance of the coating film and the wear resistance. In view of the properties, usually (a1) / (a2) = 0.5 / 99.5 to 20/80, preferably 3/97 to 10/97 to 90, more preferably 5/95 to 10/90% by mass. It is. Here, the total amount of (a1) and (a2) is 100% by mass.

(A) The weight average molecular weight (Mw) of the hydroxyl group-containing (meth) acrylic copolymer is 10,000 to 100,000, preferably 20,000 to 40,000. If it is less than 10,000, it becomes brittle as a coating film, and the hardness and wear resistance are insufficient, and if it exceeds 200,000, the coating film is not sufficiently formed and the appearance such as glossiness or turbidity becomes poor.
Here, the weight average molecular weight (Mw) is obtained by gel permeation chromatography (GPC) using polystyrene as a standard.
Moreover, the hydroxyl value of (A) is 50-200 normally, Preferably it is 90-200, More preferably, it is 120-180 mgKOH / g (solid content). When the hydroxyl value is less than 50 mgKOH / g, the coating film has a low crosslinking density, so the strength and hardness of the coating film are insufficient. On the other hand, when the hydroxyl value exceeds 200 mgKOH / g, the flexibility of the coating film is inferior. In addition to problems with impact resistance, the appearance may deteriorate.

Further, the calculated glass transition temperature (Tg) of (A) is 20 to 80 ° C., preferably 30 to 50 ° C. If it is less than 20 ° C., sufficient wear resistance is not exhibited. If it exceeds 80 ° C., the coating film becomes hard and brittle, and the friction resistance is lowered.
The glass transition temperature Tg calculated from the composition of the acrylic copolymer can be determined by the well-known method Fox formula. Fox's formula is for calculating the Tg of a copolymer based on the Tg of the homopolymer of each monomer that forms the copolymer. Bulletin of the American Physical Society, Series 2, Vol. 1, No. 3, 123 (1956), Bulletin of the American Physical Society, Series 2 (Bulletin of the American Physical Society, Series 2). The Tg of compounds having various reactive unsaturated bonds, which is the basis for calculating the Tg of the copolymer according to the Fox formula, is, for example, Shin Polymer Library, Vol. 7, Introduction to Synthetic Resins for Paints (Kyozo Kitaoka) Authors, Kobunshi Shuppankai, Kyoto, 1974) Numerals described in Table 10-2 (main raw material monomers for acrylic resins for paints) in paragraphs 168 to 169 can be used.

  As the radical polymerization initiator used in the acrylic copolymer (A) of the present invention, the following initiators can be used. Examples of organic peroxides include benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butyl hydroperoxide, cumene hydroperoxide, and the like. Examples thereof include azobisisobutyronitrile, 4,4′-azobis (4-cyanopentanoic acid), and if necessary, dodecyl mercaptan, mercaptoethanol, α-methylstyrene dimer or the like is used as a chain transfer agent. Can do.

The solvent used for dissolving and dispersing the (A) hydroxyl group-containing (meth) acrylic copolymer of the present invention is not particularly limited as long as the polymer can be completely dissolved and removed by evaporation. Two or more solvents can be mixed in order to improve the preferred viscosity, evaporation rate, and degree of whitening of the coating film.
For example, alkylbenzene solvents such as benzene, toluene, xylene, etc., acetate solvents such as ethyl acetate, propyl acetate, butyl acetate, amyl acetate, methyl acetoacetate, ketones such as dioxane, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone Solvent. In addition, (A) and the organic solvent may be formed into a paint by further adjusting the solid content and viscosity of the paint according to the coating equipment and the coating method when forming the coating film.

[(B) polyisocyanate compound]
(B) As a polyisocyanate compound, the polyisocyanate compound obtained by a general manufacturing method can be used. Of these, preferred polyisocyanate compounds are non-yellowing hexamethylene diisocyanate and derivatives thereof, tolylene diisocyanate and derivatives thereof, 4,4-diphenylmethane diisocyanate and derivatives thereof, xylylene diisocyanate and derivatives thereof, isophorone diisocyanate and derivatives thereof. Etc. In particular, these isocyanurate bodies or burette bodies are preferred in terms of reactivity and wear resistance of the coating film.
The molar ratio of NCO / OH of (A) hydroxyl group-containing (meth) acrylic copolymer and (B) polyisocyanate compound is 0.8 to 1.8 in terms of the appearance and wear resistance of the coating film, preferably 1.2 to 1.5.
The coating resin composition of the present invention can be further added with additives such as pigments, ultraviolet absorbers, antioxidants, leveling agents, fine particles and the like, if necessary. It can be used not only as an intermediate coating, but also as a clear coating or a colored coating.
In order to further improve the abrasion resistance, this coating composition may be mixed with a lubricant component or a higher alcohol (C8 to C30) such as 2-ethylhexyl alcohol or lauryl alcohol.

[Coating method]
The resin composition for coatings of the present invention can be coated on a substrate or the like by each method and can form a coating film by heating and drying at 80 ° C. for about 30 minutes. In addition, as the base material, for example, iron, aluminum, zinc, stainless steel and metal materials such as those subjected to surface treatment, vinyl chloride, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, and those subjected to surface treatment, etc. Examples include plastic materials. Moreover, the base material by which the primer, the intermediate coating, and the top-coat coating material were applied to these base materials as needed can also be used.
The coating method of the coating resin of the present invention can be performed by a known coating method such as spray, brush, roller, immersion, bar coater, or the like. The coating thickness is usually in the range of 1 to 50 μm, preferably 15 to 20 μm.

[Coating]
In the present invention, the abrasion resistance measured by the taper abrasion test method of the coating film is 500 times or more, preferably 1000 times or more. The taper wear test is measured according to the wear test method (JIS K5600-5-9), and the measurement method is a wear test by the wear wheel method (CS10P, load 500 g), and the coating film is scraped off visually. The number of revolutions until the coating film was removed from the base material until the change occurred was read.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.
Example 1
1350 g of butyl acetate and 570 g of methyl isobutyl ketone were charged into a 5-liter four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube and reflux condenser, and the temperature was raised to 100 ° C. while purging with nitrogen. Next, immediately after the temperature rise, 75 g of lauryl methacrylate, 750 g of methyl methacrylate, 330 g of ethyl acrylate, 345 g of 2-hydroxyethyl methacrylate and polymerization initiator t-butylperoxy-2-ethylhexanoate were continuously added for 5 hours with a metering pump. Thereafter, a polymerization initiator t-butylperoxy-2-ethylhexanoate was further added at 100 ° C., and the mixture was kept for 3 hours to obtain a methacrylic copolymer 1. The methacrylic copolymer 1, HDI nurate and diluted thinner (butyl acetate / ethyl acetate / propylene glycol monomethyl ether acetate = 4/4/2) were used for dilution adjustment to a solid content of 45%. The diluted composition was applied to a hot-dip galvanized steel sheet (plate thickness of 0.5 mm) with a bar coater so that the dry film thickness was 15 to 20 μm, and the atmosphere was 80 ° C. with a hot air dryer. Each test piece was prepared by drying for about 30 minutes. The obtained test piece was subjected to coating film evaluation for each item. The results are shown in Table 2.

Examples 2-8, Comparative Example 1
The coating film evaluation was performed in the same manner as in Example 1 except that the long-chain alkyl (meth) acrylate and the compound having a reactive unsaturated bond shown in Table 1 were changed, and the results are shown in Table 2.
In addition, the meaning of the symbol in Table 1 is as follows. LMA; lauryl methacrylate, StMA; stearyl methacrylate, MMA; methyl methacrylate, EA; ethyl acrylate, HEMA; 2-hydroxyethyl methacrylate, MIBK; methyl isobutyl ketone. Each blending amount is the total weight of (a1) and (a2). Was set to be 100, and the amount of diluent also corresponded to this.

[Coating film evaluation method]
Coating Film State (1) Appearance: The prepared test piece coating film was visually observed and evaluated by the following method.
○: Transparent △: Slightly cloudy ×: Opaque (white turbidity)
Coating physical properties (2) Adhesion (cross-cut adhesion): The prepared test piece coatings were subjected to an adhesion test according to a cross-cut method (JIS K5600-5-6) and observed, and evaluated by the following methods.
Number of remaining cells / number of cells when cutting.
(3) Abrasion resistance: The coating film of the prepared test piece was subjected to a wear test by the wear ring method (CS10P, load 500 g) of the taper wear test method (JIS K5600-5-9), and the paint film was scraped off visually. The number of revolutions until the change such as the film was removed or the coating film dropped from the substrate was read.

As described above, according to the results described in Table 2, in the examples, a coating film having good adhesion, including the appearance of the coating film, is obtained, and excellent performance is shown in terms of wear resistance. On the other hand, in the comparative example, the wear resistance is very poor, and it can be seen that it is clearly inferior in comparison with the example.

When coating a coating film in order to prevent wear and damage of metal and plastic materials such as automobile parts and home appliances, it is suitable for applications that require durability against abrasion or damage of the coating film.

Claims (4)

(A) A composition containing a hydroxyl group-containing (meth) acrylic copolymer and (B) a polyisocyanate compound (B), wherein (A) is an alkyl (meth) having (a1) an alkyl chain having 10 to 30 carbon atoms. The resin composition for coating materials containing an acrylate and the compound containing reactive unsaturated bonds other than (a2) (a1). The mass% of the (a1) alkyl chain (C10-30) alkyl (meth) acrylate and the compound containing a reactive unsaturated bond other than (a2) and (a1) described above is (a1) / (a2). = 0.5 / 99.5 to 20/80. The coating resin composition according to claim 1. (A) The resin composition for coatings of Claim 1 whose weight average molecular weight (Mw) of a hydroxyl-containing (meth) acrylic copolymer is 10,000 or more. The coating film containing the resin composition for paints according to claim 1, wherein the abrasion resistance measured by a taper abrasion test method (JIS K5600-5-9) is 500 times or more.