JP2007302835A - Acrylic resin composition for coating use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic resin composition for coating use highly adhesive to hardly-bondable base materials including glass fiber-reinforced polyphenylene sulfides, carbon fiber-reinforced aromatic polyamide resins and polyolefins. <P>SOLUTION: The acrylic resin composition for coating use comprises (A) an acrylic resin copolymerized with 20-100 wt.% cyclohexyl acrylate and (B) a second acrylic resin 65-170°C in glass transition temperature obtained by copolymerization of 20-100 wt.% of a cycloalkyl group-containing (meth)acrylic ester monomer and 0-80 wt.% of another (meth)acrylic ester monomer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to organic polymers such as acrylonitrile / styrene / butadiene resin (ABS resin), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyamide resin (NY), polypropylene (PP), and polyester resin (PES). The present invention relates to an acrylic resin composition for paints having good adhesion to various substrates such as inorganic materials such as glass and ceramic building materials.

  It is necessary that the paint and the pressure-sensitive adhesive strongly adhere to or adhere to the target substrate. In the case of paints, adhesion is an important theme. In the case of a pressure-sensitive adhesive, particularly a functional film for a protective film or a flat panel display, strong adhesion to a substrate film and removability to an adherend (for example, glass) are required. In any case, it is still necessary to firmly adhere to the substrate.

  In recent years, the development of products for super engineering plastics such as polypropylene (PP) alloy that is relatively easy to recycle, PPS reinforced with glass and carbon fiber with good heat resistance and deformation characteristics has become an important issue in the paint industry. Yes. These materials are generally difficult to adhere to, and it is currently impossible to develop products with good adhesion on the extension lines of conventional paints.

  Similarly, in the pressure-sensitive adhesive industry, aromatic polyamides and polyimide base materials are frequently used from the viewpoint of improving heat resistance, and those that adhere firmly like paints and exhibit adhesiveness have been desired.

  The technique which mix | blended the coating material which mix | blended chlorinated polypropylene as a coating material for polypropylene (PP) alloys, or mix | blended the chlorinated polypropylene modified acrylic resin is disclosed (refer patent document 1 and patent document 2). These techniques are intended to improve adhesion by compatibility between a polypropylene portion of a polypropylene (PP) alloy (for example, used for an automobile bumper, an instrument panel and the like) and a polypropylene unit of chlorinated polypropylene. Certainly, as disclosed, decent adhesion to a particular polypropylene (PP) alloy is demonstrated if the paint formulation is designed pinpoint. However, unfortunately, as is well known, polypropylene (PP) is a technology that can be applied evenly to all PP alloys that are premised on recycling because the crystal structure and the degree of crystallization change with the heat history during molding. Clearly not. Furthermore, on the other hand, the use of an organic polymer compound containing chlorine called chlorinated polypropylene on the other hand has been overturned despite the fact that it is recycled on the one hand and ecological measures are taken into consideration.

  In addition, a technique for blending a compound having an amino group and a silane coupling agent having an amino group as a coating for polyphenylene sulfide (PPS), which is extremely difficult to adhere, is disclosed (see Patent Documents 3 and 4). . Unfortunately, polyphenylene sulfide (PPS) is a crystalline polymer. Moreover, in order to improve shape stability and in order to improve an intensity | strength, generally it is rarely used independently and it is used in the state with which glass fiber was mix | blended as a glass fiber reinforcement grade. Although the proposed technique may show adhesion immediately after molding, it is inevitable that the adhesion deteriorates over time and becomes easy to peel off. It is hard to say that the technology satisfies the requirements sufficiently.

  Furthermore, an acrylic coating composition or the like has been proposed as one that exhibits good adhesion to polyolefin (see Patent Documents 5, 6, and 7). These technologies include 30 to 100% by mass of an acrylic copolymer (A) containing a (meth) acrylic acid ester monomer unit having an ester group of secondary alcohol or tertiary alcohol and carboxylic acid, and acrylic copolymer. It is composed of 0 to 70% by mass of another polymer (B) different from the polymer (A). (Meth) acrylic acid ester monomers having an ester group of secondary alcohol or tertiary alcohol and carboxylic acid include (meth) acrylic acid cyclohexyl, (meth) acrylic acid 4-tert-butylcyclohexyl, (meth) acrylic Illustrative is isobornyl acid.

  The proposals described in Patent Documents 5, 6, and 7 are excellent in adhesion to polyolefins such as polypropylene (PP) alloy and polyethylene and have stable performance when only the acrylic copolymer (A) is used. However, when the acrylic copolymer (A) is used alone, it has a poor solvent resistance due to the inability to take a crosslinked structure and a low (or high) glass transition temperature, and it was exposed to the natural environment. In this case, the oil film is likely to get dirty.

  On the other hand, in the polymer blend of the acrylic copolymer (A) and the acrylic copolymer (B) obtained by copolymerizing a monomer different from the monomer constituting the acrylic copolymer (A), Due to the incompatibility between the copolymer (A) and the acrylic copolymer (B), the results as proposed in Patent Documents 5, 6, and 7 cannot be obtained. It is well known in the paint industry that adhesion deteriorates due to incompatibility.

In the polymer blend of the acrylic copolymer (A) and the acrylic copolymer (B) obtained by copolymerizing a monomer different from the monomer constituting the acrylic copolymer (A), The basic performances such as transparency, gloss, color tone, color stability and sharpness of the coating film cannot be obtained. Furthermore, when the acrylic copolymer (A) is used alone, it has a poor solvent resistance and is exposed to the natural environment because it cannot take a crosslinked structure and has a low (or high) glass transition temperature. If this happens, the oil film is likely to get dirty.
JP 2005-290314 A JP 2003-55597 A JP 2002-309165 A JP 2000-226536 A JP 2004-315668 A JP 2004-196990 A JP 2004-307577 A

  The present invention is typified by super engineering plastic typified by glass fiber reinforced polyphenylene sulfide (PPS), carbon fiber reinforced aromatic polyamide resin (NY), and polypropylene (PP) alloyed with ethylene-propylene copolymer. The present invention provides an acrylic resin composition for paints that has perfect and strong adhesion to difficult-to-adhere substrates such as polyolefin.

  The present invention includes an acrylic resin (A) copolymerized with 20 to 100% by weight of cyclohexyl acrylate, a cycloalkyl group-containing (meth) acrylic acid ester monomer of 20 to 100% by weight, and other (meth) It is the acrylic resin composition for coating materials containing the acrylic resin (B) whose glass transition temperature copolymerized with 0-80 weight% of acrylate monomers is 65-170 degreeC.

  The acrylic resin composition for paints of the present invention comprises an acrylonitrile / styrene / butadiene resin (ABS resin), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyamide resin (NY), polypropylene (PP), polyester resin ( It has good adhesion to various substrates such as organic polymers such as PES), glass, and inorganic materials such as ceramic building materials.

  It should be noted that the acrylic resin composition for paints of the present invention is alloyed with super engineering plastics such as glass fiber reinforced polyphenylene sulfide (PPS) and carbon fiber reinforced aromatic NY, and ethylene-propylene copolymer. In addition, it has perfect and strong adhesion to difficult-to-adhere substrates such as polyolefins typified by PP.

  The acrylic resin composition for paints of the present invention exhibits good adhesion to various difficult-to-adhere substrates, and the coating film has good scratch resistance and flexibility.

  The glass transition temperature (hereinafter also referred to as Tg) of the copolymer that appears in the following description was calculated by a method described in the literature (reference: “mechanical properties of polymer”, JE NIELSEN). Written and translated by Shigeharu Onoki, p26-p27, Kagaku Dojin (1975).

  The acrylic resin composition for coatings of the present invention comprises an acrylic resin (A) copolymerized with 20 to 100% by weight of cyclohexyl acrylate, and a cycloalkyl group-containing (meth) acrylate monomer 20 to 100% by weight. And an acrylic resin composition for coatings containing an acrylic resin (B) having a glass transition temperature of 65 to 170 ° C., which is copolymerized with 0 to 80% by weight of other (meth) acrylic acid ester monomers.

  In the acrylic resin composition for paints of the present invention, cyclohexyl acrylate can be arbitrarily selected from those on the market and used.

  The acrylic resin (A) is copolymerized with 20 to 100% by weight of cyclohexyl acrylate. It is recommended that cyclohexyl acrylate be copolymerized, preferably 30-100% by weight, more preferably 60-98% by weight. When the copolymerization amount of cyclohexyl acrylate is less than 20% by weight, the adhesion to difficult-to-adhere substrates such as polyphenylene sulfide (PPS) and polypropylene (PP) alloy is deteriorated.

  In the acrylic resin (A), when the copolymerization amount of cyclohexyl acrylate is 100% by weight (cyclohexyl acrylate homopolymer), the adhesion to various substrates is very good.

  When the amount of cyclohexyl acrylate copolymer is 100% by weight, the coating film tends to be soft. In order to eliminate the adhesiveness of the coating film, improve the contamination of the coating film, and make the coating film less likely to be damaged, when the amount of cyclohexyl acrylate copolymer is 100% by weight, the acrylic resin (A) is subjected to radical polymerization. It is recommended that a chain transfer agent having an active hydrogen atom group other than a mercapto group such as thioglycolic acid, thiopropionic acid, thioethanol, etc. be used in combination.

  When the acrylic resin (A) is produced by radical polymerization, the use of a chain transfer agent having an active hydrogen atom group other than a mercapto group such as thioglycolic acid, thiopropionic acid, thioethanol, etc. Is preferably 20% by weight or more and less than 100% by weight. Thereby, the softening of a coating film can be improved and the tendency for adhesiveness, stain resistance, and scratch resistance to improve is seen. At the same time, integration with the acrylic resin (B) can be achieved, and the design properties such as transparency, sharpness, and gloss of the coating film tend to be improved.

  In the acrylic resin composition for coatings of the present invention, as other (meth) acrylic acid ester monomers copolymerizable with cyclohexyl acrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, acrylic acid t -Butyl, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, 2,2,2-trifluoroethyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, methacryl Cyclohexyl acid, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, 2,2,2-trifluoroethyl methacrylate, acrylic acid, methacrylic acid, maleic acid, itaconic acid, 2-hydroxyethyl acrylate, acrylic acid 2-hydroxyp Pill, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, N, N-dimethylacrylamide, Examples include 2-hydroxyethyl acrylamide, N, N-dimethylaminoethyl methacrylate, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, and the like. The (meth) acrylic acid ester monomer may be used alone or as a mixture of two or more.

  In the acrylic resin composition for paints of the present invention, the acrylic resin (A) has a Tg of preferably −50 to 50 ° C., more preferably −30 to 30 ° C., and still more preferably −10 to 30 ° C. It is recommended that there be. When the Tg of the acrylic resin (A) is less than −50 ° C., there is a tendency that the polymer cohesive force is lowered and the adhesion is deteriorated. Moreover, when Tg of acrylic resin (A) is less than -50 degreeC, there exists a tendency for adhesiveness to remain in a coating film, and stain resistance and damage resistance may deteriorate. When the Tg of the acrylic resin (A) exceeds 50 ° C., the tendency of the coating film to become brittle is similarly observed, and the adhesion may be deteriorated. Further, there is a tendency that the leveling property and sharpness tend to be deteriorated, which tends to increase the viscosity of the paint.

  In the acrylic resin composition for paints of the present invention, the acrylic resin (A) can be produced by well-known ordinary radical polymerization. That is, it can be produced by solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like.

  Examples of production by solution polymerization include toluene, xylene, ethyl acetate, butyl acetate, cyclohexane, methylcyclohexane, cyclohexanone, propylene glycol monomethyl ether, propylene glycol monobutyl ether, butyl cellosolve, and the like. Organics such as α, α-azobisisobutyronitrile, azobisvaleronitrile, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, benzoyl peroxide as a polymerization initiator at 150 ° C. It can be produced by performing radical polymerization of cyclohexyl acrylate and other (meth) acrylic acid ester monomers using an azo compound and an organic peroxide. In order to prevent coloring of the polymer, it is desirable to blow in an inert gas such as nitrogen gas or helium gas during the polymerization.

  In the production of the acrylic resin (A), a chain transfer agent such as n-dodecyl mercaptan, thioglycolic acid, thioethanol, or α-styrene dimer can be used for molecular weight adjustment if necessary. These chain transfer agents may be used alone or as a mixture of two or more.

  More preferably, in the production of the acrylic resin (A), a chain transfer agent having an active hydrogen atom-containing group other than a mercapto group in a molecule such as thioglycolic acid, thiopropionic acid or thioethanol is used for molecular weight control. It is. By using these chain transfer agents, active hydrogen atoms can be efficiently introduced into the polymer terminal of the acrylic resin (A), and a tougher coating film can be formed. Furthermore, when blended with acrylic resin (B), for example, when urethane cross-linking is performed, integration with acrylic resin (B) is made, and compatibility between acrylic resin (A) / acrylic resin (B) jumps. The effect is excellent in many performances such as transparency, gloss, adhesion, and flexibility of the coating film.

  In the acrylic resin composition for paints of the present invention, the acrylic resin (B) is copolymerized with 20 to 100% by weight of a cycloalkyl group-containing (meth) acrylic acid ester monomer. The acrylic resin (B) is preferably 30 to 100% by weight, and more preferably 50 to 98% by weight. When the copolymerization amount of the cycloalkyl group-containing (meth) acrylic acid ester monomer is less than 20% by weight, the compatibility with the acrylic resin (A) tends to be deteriorated, and the precipitation and separation of the paint, etc. The storage stability of the film tends to deteriorate, and the uniformity, transparency, sharpness, gloss and adhesion of the coating film may deteriorate.

  In the acrylic resin composition for paints of the present invention, a cycloalkyl group-containing (meth) acrylic acid ester monomer is copolymerized with the acrylic resin (B). Cycloalkyl group-containing (meth) acrylic acid ester monomers include cyclohexyl acrylate, isobornyl acrylate, dicyclopentanyloxy acrylate, dicyclopentanyloxyethyl acrylate, cyclohexyl methacrylate, isobornyl methacrylate, dicyclopentenyl Examples thereof include oxymethacrylate, dicyclopentanyloxyethyl methacrylate and 3,4-epoxycyclohexylmethyl methacrylate. These cycloalkyl group-containing (meth) acrylic acid ester monomers may be copolymerized alone or in a mixture of two or more.

  Among the copolymerization amounts of these cycloalkyl group-containing (meth) acrylic acid ester monomers, cyclohexyl methacrylate, dicyclopentanyloxy methacrylate, cyclohexyl acrylate, and dicyclopentanyloxy acrylate can be preferably used. . By copolymerizing these monomers, a large effect tends to be seen in improving compatibility with the acrylic resin (A). Furthermore, there is a tendency that the storage stability, adhesion, uniformity, transparency, gloss and the like of the paint are improved by improving the compatibility.

  In the acrylic resin (B), other (meth) acrylic acid ester monomers that can be used by copolymerizing with a cycloalkyl group-containing (meth) acrylic acid ester monomer include methyl acrylate, ethyl acrylate, acrylic acid n-butyl, t-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, 2,2,2-trifluoroethyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, T-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, 2,2,2-trifluoroethyl methacrylate, acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylic acid 2-hydroxyethyl, a 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, N, Examples thereof include N-dimethylacrylamide, 2-hydroxyethylacrylamide, N, N-dimethylaminoethyl methacrylate, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyltriethoxysilane. The (meth) acrylic acid ester monomer may be used alone or as a mixture of two or more.

  The acrylic resin (B) can be produced by radical copolymerization in the same manner as the acrylic resin (A).

  It is recommended that the acrylic resin (B) has a Tg of preferably 65 to 170 ° C, more preferably 80 to 170 ° C, and still more preferably 100 to 150 ° C. When the Tg of the acrylic resin (B) is less than 65 ° C., there are cases where the coating film is soft and the coating film remains slightly sticky. There is a tendency for scratch resistance and contamination resistance to deteriorate. When the Tg of the acrylic resin (B) exceeds 170 ° C., there is a tendency that the paint viscosity becomes high and the coating workability deteriorates. As a result, the coating appearance, uniformity, gloss, etc. may be slightly deteriorated.

  The acrylic resin (B) preferably has at least one functional group selected from a carboxyl group, a hydroxyl group, and an epoxy group. These functional groups are copolymerized in the acrylic resin (B), preferably 0.5 to 30% by weight, more preferably 0.8 to 25% by weight, and still more preferably 1.0 to 22% by weight. Is desirable. When the copolymerization amount is less than 0.5% by weight, the effect of introducing a functional group is dilute, and there is a tendency that no remarkable improvement effect on adhesion and crosslinkability is observed. When the copolymerization exceeds 30% by weight, the coating film becomes too hard and tends to be brittle and easily cracked. Further, distortion during the curing reaction and the crosslinking reaction tends to remain in the coating film, and the followability to bending and extrusion tends to be impaired.

  In order to introduce at least one functional group selected from a carboxyl group, a hydroxyl group, and an epoxy group into the acrylic resin (B), for example, a carboxyl group-containing acrylic monomer such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid is used. Hydroxyl group-containing acrylic monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, etc. An epoxy group-containing acrylic monomer such as a monomer, glycidyl methacrylate, or 3,4-epoxycyclohexylmethyl methacrylate may be copolymerized.

  By introducing at least one functional group selected from a carboxyl group, a hydroxyl group, and an epoxy group into the acrylic resin (B), good pigment dispersibility and leveling properties can be imparted to the paint. Furthermore, using these functional groups, for example, bisphenol A type epoxy resin, epoxy group-containing compounds such as γ-glycidoxypropyltrimethoxysilane, polyisocyanate compounds such as hexamethylene diisocyanate and isophorone diisocyanate, N, The coating film has a tough cross-linking structure by blending a cross-linking agent such as amino group-containing compounds such as N-dimethylaminopropylamine and γ-aminopropylltriethoxysilane, and compounds having a phenol group such as terpenephenol resin. This is recommended because it can further enhance the durability, scratch resistance, and flexibility of the coating film.

  In the acrylic resin composition for paints of the present invention, the acrylic resin (A) and the acrylic resin (B) are acrylic resin (A) when the total amount of the acrylic resin (A) and the acrylic resin (B) is 100% by weight. The blending amount of A) is preferably 5% by weight or more and less than 100% by weight, more preferably 10 to 90% by weight, and still more preferably 30 to 85% by weight. When the blending amount of the acrylic resin (A) is less than 5% by weight, there are cases where adhesion and flexibility are inferior. In particular, a tendency to be prominent is observed in the case of a hardly adherent substrate such as PPS and PP alloy.

  The acrylic resin composition for coatings of the present invention is suitable for coatings for inorganic polymers such as organic polymer coatings, glass and ceramic building materials, and more preferably coatings for acrylonitrile / styrene / butadiene resins (ABS resins). , Paint for polyphenylene sulfide (PPS), paint for polyetheretherketone (PEEK), paint for polyamide resin (NY), paint for polypropylene (PP), paint for polyester resin (PES) Can do.

  Further, the acrylic resin composition for paints of the present invention is represented by PP for alloying with paints for super engineering plastics such as glass fiber reinforced PPS and carbon fiber reinforced aromatic NY, and ethylene-propylene copolymer. It is suitably used for a polyolefin coating.

  Hereinafter, the present invention will be described in detail with reference to examples.

  In the examples and comparative examples, the composition ratio represents a weight ratio unless otherwise specified. The molecular weight was measured by GPC (gel permeation chromatography) using standard polymethyl methacrylate as the molecular weight standard.

  Adhesion was tested and evaluated according to the cross cut test method described in JIS K 5400 (1987). It was considered as passing at 100/100. The pencil hardness was tested and evaluated by a pencil scratch resistance test described in JIS K 5400 (1987). As a measure of scratch resistance of the coating film, it was determined to be acceptable if B or higher. The flexibility was tested and evaluated by a flexibility test described in JIS K 5400 (1987). As a measure of the flexibility and toughness of the coating film, 5 mmφ or less was accepted.

Example 1
Using butyl acetate as a solvent, α, α-azobisisobutyronitrile as a polymerization initiator, radical polymerization of cyclohexyl acrylate using thioethanol as a chain transfer agent, Mn 40,000, solid content 50.3% Acrylic resin (A-1) (Tg = 20 ° C.) was produced.

  Similarly, α, α-azobisisobutyronitrile is used as a polymerization initiator with butyl acetate as a solvent, and the monomer composition is dicyclopentanyloxy methacrylate (homopolymer Tg = 170 ° C.) / Acrylic acid A mixed monomer of cyclohexyl / 2-hydroxyethyl methacrylate (Tg of homopolymer = 40 ° C.) (= 75/10/15) was radically polymerized, and an acrylic resin (Mn = 57,000, solid content 40.2%) B-1) (Tg = 125 ° C.) was produced.

  Acrylic resin (A-1) and acrylic resin (B-1) were mixed at a solid content ratio of 70/30 to 30/70, and butyl acetate was added to adjust the solid content to 30%. As a curing agent, "Sumidule N-3300" (product of Sumitomo Bayer Urethane Co., Ltd., urethane curing agent) is used as the number of moles of NCO group of the curing agent / number of moles of OH group of acrylic (hereinafter also referred to as NCO index). Was mixed to 1.2 and stirred until uniform. This paint was applied to various substrates shown in Tables 1, 2, and 3 so that the dry film thickness was 25 μm, and dried at 80 ° C. for 20 minutes. The test was further conducted after curing at 23 ° C. for 1 week. Tables 1, 2 and 3 show the adhesion, scratch resistance, and flexibility test results.

  As shown in Tables 1, 2 and 3, acrylic resin (A-1) (thioethanol is used as a chain transfer agent) and acrylic resin (B-1) (cycloalkyl group-containing (meth) acrylate 85% copolymerized In order to improve compatibility, acrylic urethane paints that are polymer blended with 10% cyclohexyl acrylate) show good adhesion to various difficult-to-adhere substrates, and the coating is scratch resistant. Excellent in flexibility and flexibility.

Example 2
Using butyl acetate as a solvent, α, α-azobisisobutyronitrile as a polymerization initiator, thioethanol as a chain transfer agent, cyclohexyl methacrylate (Tg of homopolymer = 60 ° C.) / Cyclohexyl acrylate (= 80 / 20) was radical-polymerized to produce an acrylic resin (A-2) (Tg = 51 ° C.) having a Mn of 45,000 and a solid content of 48.5%.

  Similarly, α, α-azobisisobutyronitrile is used as a polymerization initiator with butyl acetate as a solvent, and the monomer composition is dicyclopentanyloxy methacrylate / cyclohexyl methacrylate / cyclohexyl acrylate / methacrylic acid. Radical polymerization of a mixed monomer of 2-hydroxyethyl (= 30/20/30/20), and acrylic resin (B-2) (Tg = 67 ° C.) with Mn = 62,000 and a solid content of 40.2% Manufactured.

  The acrylic resin (A-2) and the acrylic resin (B-2) were mixed at a solid content ratio of 70/30 to 30/70, and butyl acetate was added to adjust the solid content to 30%. “Sumidur N-3300” as a curing agent was added to this so that the NCO index was 1.2, and stirred until uniform. This paint was applied to various substrates shown in Tables 4, 5, and 6 so that the dry film thickness was 25 μm, and dried at 80 ° C. for 20 minutes. The test was further conducted after curing at 23 ° C. for 1 week. Tables 4, 5, and 6 show the adhesion, scratch resistance, and flexibility test results.

  As shown in Tables 4, 5 and 6, acrylic resin (A-2) (using thioethanol as chain transfer agent) and acrylic resin (B-2) (cycloalkyl group-containing (meth) acrylic acid ester monomer Acrylic urethane paint with a polymer blend of 80% copolymerization and 20% copolymerization of cyclohexyl acrylate to improve compatibility shows good adhesion to various difficult-to-adhere substrates. The film was also excellent in scratch resistance and flexibility.

Comparative Example 1
Acrylic resin (C-1) was produced by radical polymerization of methyl methacrylate (homopolymer Tg = 104 ° C.) using butyl acetate as a solvent and α, α-azobisisobutyronitrile as a polymerization initiator. Mn of the acrylic resin (C-1) was 58,000. The solid content was 40.2%. Acrylic resin (C-1) was applied to various substrates shown in Table 7 so that the dry film thickness was 25 μm, and dried at 80 ° C. for 20 minutes. The adhesion test results are shown in Table 7.

  Acrylic resin (C-1) in which cyclohexyl acrylate or cycloalkyl group-containing (meth) acrylic acid ester monomer was not copolymerized had no adhesion to the substrate.

At the same time, when a flexibility test was performed on a Lumirror T-60 # 50 paint plate, it was 10 mmφ ×. There was no flexibility of the coating film.

Comparative Example 2
Using butyl acetate as a solvent and α, α-azobisisobutyronitrile as a polymerization initiator, radical polymerization of cyclohexyl acrylate (homopolymer Tg = 20 ° C.) gives a number average molecular weight (hereinafter also referred to as Mn). 200,000 acrylic resins (A-3) (A-3 does not use a chain transfer agent) were produced. The solid content was 50.0%. The acrylic resin (A-3) was applied to the PP alloys shown in Tables 8 and 9 so that the dry film thickness was 25 μm, and dried at 80 ° C. for 20 minutes. The adhesion test results are shown in Table 8. Table 9 shows the coating hardness test results (scratch resistance).

  The acrylic resin (A-3) showed a tendency that the coating film was soft and easily damaged.

Comparative Example 2
The acrylic resin (A-1) and the acrylic resin (C-1) were mixed at 80/20 and tested. The mixed solution was cloudy immediately after mixing, but started to be separated from about the first day, and became a separated solution having an upper layer portion and a lower layer portion in about 3 weeks. The acrylic resin (A-1) is not compatible with the acrylic resin (C-1) in which the cycloalkyl group-containing (meth) acrylic acid ester monomer is not copolymerized at all, and the storage stability of the paint is poor. there were.

  The mixed paint was applied to various substrates shown in Table 10 so that the dry film thickness was 25 μm, and dried at 80 ° C. for 20 minutes. The adhesion test results are shown in Table 10.

  Since the acrylic resin (A-1) and the acrylic resin (C-1) are poorly compatible, the acrylic resin (A-1) was not adhesive even though 80% was blended. .

Claims (4)

  Acrylic resin (A) copolymerized with 20 to 100% by weight of cyclohexyl acrylate, 20 to 100% by weight of cycloalkyl group-containing (meth) acrylic acid ester monomer, and other (meth) acrylic acid ester units An acrylic resin composition for paints, comprising an acrylic resin (B) having a glass transition temperature of 65 to 170 ° C. obtained by copolymerizing 0 to 80% by weight of a monomer.   The cycloalkyl group-containing (meth) acrylic acid ester monomer is at least one monomer selected from the group consisting of cyclohexyl methacrylate, dicyclopentanyloxy methacrylate, cyclohexyl acrylate, and dicyclopentanyloxy acrylate. The acrylic resin composition for paints according to claim 1, which is contained.   The acrylic resin for paint according to claim 1 or 2, wherein the other (meth) acrylic acid ester monomer includes a monomer having at least one functional group selected from a carboxyl group, a hydroxyl group, and an epoxy group. Composition.   The acrylic resin (A) is polymerized in the presence of at least one chain transfer agent selected from the group of thioglycolic acid, thiopropionic acid, and thioethanol. Acrylic resin composition for paints.