JP2007308528A - Acrylic resin composition for coating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic resin composition for coating materials that has perfect and strong adhesiveness to a hard-to-be-attached substrate such as polyolefin represented by a polypropylene (PP) alloyed with an ethylene-propylene copolymer and the like. <P>SOLUTION: The acrylic resin composition for coating materials comprises an acrylic resin (A) having cyclohexyl acrylate copolymerized in an amount of 20-100 wt.%, wherein the acrylic resin (A) is polymerized in the presence of at least one chain transfer agent selected from the group consisting of thioglycolic acid, thiopropionic acid and thioethanol. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an acrylic resin composition for paint having good adhesion to polypropylene (PP).

  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, in the paint industry, it is important to develop products for super engineering plastics such as polypropylene (PP) alloys that are relatively easy to recycle, polyphenylene sulfide (PPS) reinforced with glass and carbon fibers with good heat resistance and deformation characteristics. It has become a challenge. 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.

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 a chlorinated polypropylene. Certainly, as disclosed, decent adhesion to a particular PP alloy is achieved when the paint formulation is designed pinpoint. However, unfortunately, as is well known, PP is not a technology that can be applied evenly to all polypropylene (PP) alloys that are premised on recycling, as the crystal structure and the degree of crystallization change depending on the thermal history during molding. It is clear. 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.
JP 2005-290314 A JP 2003-55597 A

  The present invention relates to an acrylic resin composition for paints having perfect and strong adhesion to a difficult-to-adhere substrate such as polyolefin represented by polypropylene (PP) alloyed with an ethylene-propylene copolymer. Is to provide.

  The present invention includes an acrylic resin (A) copolymerized with 20 to 100% by weight of cyclohexyl acrylate, and the acrylic resin (A) is at least selected from the group of thioglycolic acid, thiopropionic acid, and thioethanol. It is the acrylic resin composition for coatings which is polymerized in the presence of one kind of chain transfer agent.

  The acrylic resin composition for paints of the present invention has good adhesion to polypropylene (PP). The acrylic resin composition for paints of the present invention can be applied to acrylonitrile / styrene / butadiene resin (ABS resin), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyamide resin (NY), polyester resin (PES), etc. Has good adhesion.

  The acrylic resin composition for paints of the present invention is made of polypropylene (PP) alloyed with super engineering plastics, ethylene-propylene copolymers, etc., typified by glass fiber reinforced polyphenylene sulfide (PPS), carbon fiber reinforced aromatic polyamide resin and the like. It has perfect and strong adhesion to difficult-to-adhere substrates such as polyolefins).

  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 ( While exhibiting good adhesion to difficult-to-adhere substrates such as PES), 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 paints of the present invention includes an acrylic resin (A) copolymerized with 20 to 100% by weight of cyclohexyl acrylate, and the acrylic resin (A) is thioglycolic acid, thiopropionic acid, thioethanol. Polymerized in the presence of at least one chain transfer agent selected from the group of

  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. The cyclohexyl acrylate is preferably copolymerized in an amount of 30 to 100% by weight, more preferably 60 to 98% by weight. When the copolymerization amount of cyclohexyl acrylate is less than 20% by weight, the adhesion to a hard-to-adhere substrate such as polypropylene (PP) alloy is deteriorated.

  The acrylic resin composition for paints of the present invention is obtained by polymerizing the acrylic resin (A) in the presence of at least one chain transfer agent selected from the group of thioglycolic acid, thiopropionic acid, and thioethanol. is there.

  Polymerization in the presence of at least one chain transfer agent selected from the group consisting of thioglycolic acid, thiopropionic acid, and thioethanol eliminates the tackiness of the coating film, improves the contamination of the coating film, and The film is less likely to be damaged. These chain transfer agents may be used alone or as a mixture of two or more. 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, n-dodecyl mercaptan, α-styrene dimer and the like can be added to thioglycolic acid, thiopropionic acid, and thioethanol, if necessary, for molecular weight adjustment.

  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.

  In the acrylic resin composition for paints of the present invention, the acrylic resin (A) 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 acrylic resin composition for paints of the present invention, preferably, the acrylic resin (A), the cycloalkyl group-containing (meth) acrylic acid ester monomer 20 to 100% by weight, and other (meth) acrylic acid ester units are used. An acrylic resin (B) copolymerized with 0 to 80% by weight of a monomer is included.

  In the acrylic resin composition for paints of the present invention, preferably, the acrylic resin (B) is copolymerized with 20 to 100% by weight of a cycloalkyl group-containing (meth) acrylic acid ester monomer. In the acrylic resin (B), it is preferable that the cycloalkyl group-containing (meth) acrylic acid ester monomer is copolymerized in an amount of 30 to 100% by weight, more preferably 50 to 98% by weight.

  In the acrylic resin composition for paints of the present invention, preferably, the acrylic resin (B) is copolymerized with a cycloalkyl group-containing (meth) acrylic acid ester monomer. 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.

  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.

  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, preferably, the acrylic resin (A) and the acrylic resin (B) are, when the total amount of the acrylic resin (A) and the acrylic resin (B) is 100% by weight, The blending amount of the acrylic resin (A) is preferably 5 to 100% by weight, more preferably 10 to 90% by weight, and still more preferably 30 to 85% by weight.

  Further, when the acrylic resin (A) and the acrylic resin (B) are used in a blend, the acrylic resin (A) is at least one chain transfer agent selected from the group of thioglycolic acid, thiopropionic acid, and thioethanol. For example, in the case of urethane crosslinking, the polymer is integrated with the acrylic resin (B), and the compatibility between the acrylic resin (A) / acrylic resin (B) is dramatically improved. In addition, the film exhibits excellent effects in numerous performances such as transparency, gloss, adhesion, and flexibility of the coating film.

  The acrylic resin composition for paint of the present invention can be used for paint for polypropylene (PP) and paint for polyester resin (PES).

  Furthermore, the acrylic resin composition for coatings of the present invention is made of a polypropylene (alloyed with a coating for super engineering plastics typified by glass fiber reinforced PPS, carbon fiber reinforced aromatic polyamide resin, etc., ethylene-propylene copolymer, etc. It is preferably used for polyolefin coatings typified by PP).

  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, less than 5 mmφ was accepted.

Example 1
Using butyl acetate as a solvent, α, α-azobisisobutyronitrile as the polymerization initiator, cyclohexyl acrylate (Tg of homopolymer = 20 ° C.), and thioglycolic acid as the chain transfer agent By radical polymerization, acrylic resins (A-1 to A-2) (A-1 to A-2 are cyclohexyl acrylate homopolymers) having different number average molecular weights (hereinafter also referred to as Mn) were produced. Mn of acrylic resin (A-1) and (A-2) was 20,000 and 60,000, respectively. The solid content was 49.8% and 50.0%. Acrylic resins (A-1) and (A-2) were applied to the 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 adhesion test results are shown in Table 1. The coating hardness test results (scratch resistance) are shown in Table 2, and the coating flexibility test results are shown in Table 3.

  Acrylic resin (A-1) and acrylic resin (A-2) are difficult to adhere to polyethylene terephthalate (PET) film and polyphenylene sulfide (PPS) resin, which are difficult-to-adhere substrates. Excellent adhesion to polypropylene (PP) alloy. Similarly, the coating film hardness was kept at B or higher, and the flexibility test result showed a good test result. The coating film had flexibility and excellent scratch resistance.

Example 2
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-3) (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 dicyclopentanyloxymethacrylate (homopolymer Tg = 170 ° C.) / Acrylic. Acrylic resin having Mn = 72,000 and solid content of 40.2% by radical polymerization of a mixed monomer of cyclohexyl acid / 2-hydroxyethyl methacrylate (Tg of homopolymer = 40 ° C.) (= 75/10/15) (B-1) (Tg = 125 ° C.) was produced.

  The acrylic resin (A-3) and the 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, "Sumijour 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 4 and 5 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. The adhesion test results are shown in Table 4, and the scratch resistance test results are shown in Table 5.

  The acrylic resin (B-1) is copolymerized with cyclohexyl acrylate, and the compatibility with the acrylic resin (A-3) is improved. Furthermore, since acrylic resin (A-3) uses thioethanol as a chain transfer agent, acrylic resin (A-3) and acrylic resin (B-1) are used when the paint is cured with a urethane curing agent. An integrated polymer is obtained, and the polymer composition is made uniform. As a result, an acrylic resin (B-1) having a high glass transition temperature was polymer blended, and even when the coating film hardness was increased, the adhesion was not changed and a very good result was shown. At the same time, the coating film hardness increased and scratch resistance improved.

Example 3
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 / methacrylic acid 2-Hydroxyethyl (= 72/20/8) was radically polymerized to produce an acrylic resin (A-4) (Tg = 51 ° C.) having a Mn of 32,000 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), acrylic resin (B-2) (Tg = 67 ° C.) with Mn = 73,000 and solid content of 40.2% Manufactured.

  Acrylic resin (A-4) and 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 Table 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. The adhesion test results are shown in Table 6, and the scratch resistance test results are shown in Table 7.

  The side chain hydroxyl groups of the acrylic resin (A-4) and the acrylic resin (B-2) are crosslinked and integrated with a urethane bond, and the acrylic resin (B-2) has many hydroxyl groups. Therefore, the scratch resistance of the coating film was greatly improved and the adhesion was also good.

Comparative Example 1
Using butyl acetate as a solvent, α, α-azobisisobutyronitrile as the polymerization initiator, cyclohexyl acrylate (homopolymer Tg = 20 ° C.), and n-dodecyl mercaptan as the chain transfer agent Radical polymerization was carried out to produce an acrylic resin (A-5). (A-5 is a cyclohexyl acrylate homopolymer) The number average molecular weight of the acrylic resin (A-5) was 42,000, and the solid content was 50.2%. Acrylic resin (A-5) was applied to various substrates shown in Tables 8, 9, and 10 so as to have a dry film thickness of 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), and Table 10 shows the flexibility test results of the coating films.

  The acrylic resin (A-5) is produced using n-dodecyl mercaptan as a chain transfer agent. Compared to the case where acrylic resin (A-1) or (A-2) produced using thioglycolic acid is used as a coating resin, the coating film hardness is the target when coated on polypropylene (PP) alloy. It was a coating film that was easily damaged by 1 letter or more than the pencil hardness B. To make matters worse, the flexibility of the coating film deteriorated despite the fact that the coating film became soft, resulting in a coating film with no flexibility.

Comparative Example 2
Acrylic resin (C-1) is 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. did. Mn of the acrylic resin (C-1) was 58,000. The solid content was 40.2%. The acrylic resin (C-1) was applied to various substrates shown in Table 11 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 11.

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

Claims (4)

  An acrylic resin (A) copolymerized with 20 to 100% by weight of cyclohexyl acrylate, wherein the acrylic resin (A) is at least one chain selected from the group of thioglycolic acid, thiopropionic acid, and thioethanol An acrylic resin composition for coatings, which is polymerized in the presence of a transfer agent.   The acrylic resin composition for paints according to claim 1, wherein the glass transition temperature of the acrylic resin (A) is -50 to 50 ° C.   Acrylic copolymerized with acrylic resin (A), 20 to 100% by weight of cycloalkyl group-containing (meth) acrylic acid ester monomer, and 0 to 80% by weight of other (meth) acrylic acid ester monomers The acrylic resin composition for paints according to claim 1 or 2 containing resin (B).   The acrylic resin composition for paints according to claim 3, wherein the acrylic resin (B) has a glass transition temperature of 65 to 170 ° C.