JPH11124519A - Thermosetting powder coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having an improved resistance to acid rain and storage stability by employing specified amounts of an acrylic copolymer and an organically modified polysiloxane. SOLUTION: A coating composition comprises 100 pts.wt. acrylic copolymer obtained by the polymerization of 15-60 pts.wt. monomer having an unsaturated bond capable of participating in radical polymerization and an epoxy group, such as glycidyl (meth)acrylate an 40-85 pts. wt. monomer having an unsaturated bond capable of participating in radial polymerization but no epoxy group, such as methyl (meth)acrylate, 0.01-2.0 pts.wt. organically modified polysiloxane represented by formula I or the like, and 5-60 pts.wt. curing agent such as polycarboxylic acids, for example, isophthalic acid, or anhydrides thereof. In the formula, X<1> and X<2> are groups represented by formulas II to VI; Ra , Rb , Rc , Rd and Re are each a linking bond, 1-8C alkylene, phenylene or the like; R<1> and R<2> are each a linking bond, 1-8C alkylene, phenylene or the like; R<3> to R<8> are each a 1-8C alkyl, phenyl or the like; and n1 is 1-1,500.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting powder coating composition, and more particularly, to excellent appearance characteristics (smoothness, etc.), physical characteristics (scratch resistance, recoating properties, etc.), and weather resistance. ,
UV resistance and chemical properties (acid rain resistance, solvent resistance, etc.)
The present invention relates to a thermosetting powder coating composition which can form a coating film after baking and has excellent storage stability.

[0002]

2. Description of the Related Art Powder coatings have many advantages, such as low risk of fire and toxicity, and high workability, as compared with solvent coatings. Among them, from the viewpoint of gloss, weather resistance, chemical resistance, and mechanical strength, thermosetting acrylic resins are promising, and various attempts have been made to develop thermosetting acrylic resins for powder coatings. I have. As a conventional powder coating composition containing a thermosetting acrylic resin, a copolymer of an alkyl ester of acrylic acid or methacrylic acid and a glycidyl ester of acrylic acid or methacrylic acid, the molecular weight of which is 1,000 to 30,
In general, a resin obtained by blending a thermosetting agent with an acrylic resin having a molecular weight of 000 (for example, German Patent Application Publication No. 2,057,577 and 2,014,91) is used.
No. 4 publication). However, a coating film obtained from this composition is not necessarily sufficient in its smoothness, strength, chemical resistance and metal adhesion.

Further, a composition comprising a composition comprising an acrylic resin and a curing agent, further blended with a cellulose derivative to improve the smoothness of the coating film (for example, JP-A-48-7943), or a polyepoxy A composition in which a resin is blended to improve the chemical resistance and adhesion of the coating film (for example, see JP-A-48
No. 17844) has also been proposed. However, coating films formed from powder coatings composed of these compositions were not always sufficient in strength.

[0004] With respect to solvent paints, see, for example,
JP-A-151272 discloses (A) a radical polymerizable compound mainly composed of (meth) acrylate, (B) a radical polymerizable silicone macromonomer, and (C) a crosslinkable compound having a non-radical polymerizable reactive functional group. A highly weather-resistant paint containing a graft polymer obtained by radical copolymerization with a monomer as a main component of a resin component is disclosed. However, since the silicone macromonomer of this coating is used in a high concentration (10 to 30% by weight) in the graft polymer, the coating film formed by this coating is excellent in weather resistance and solvent resistance, but is fresh. Poor in image quality and recoatability. Further, this highly weather-resistant paint is a solvent-type paint as is clear from the composition of the resin and the curing agent, and as is clear from the description of the examples. As described below, the solvent paint is not preferable from the viewpoint of environmental protection and resource saving.

Recently, environmental problems such as air pollution, global warming, and acid rain have become major problems. In particular, in the technical field of paint, from the viewpoint of a producer, air pollution poses a problem when an organic solvent generated in a large amount in a painting process or a baking process is released to the environment. On the other hand, from the consumer's point of view, when exposed products are exposed to the weather environment (rain, snow, fog, smog, etc.), soil or sewage, etc. Durability is a problem. Furthermore, when a solvent paint is used, a closed system for preventing the organic solvent from leaking into the atmosphere is required, so that it is more economical than a powder paint that does not require such a large facility. Disadvantageous. Therefore, from the viewpoints of environmental protection and resource saving, it is very effective to use a powder coating rather than a solvent coating, and the transition from the solvent coating to the powder coating is a trend of the times.

[0006] However, despite the increasing demand for powder coatings from such a background, the known powder coating technology has a coating film formed by thermosetting as compared with the solvent coating technology. Appearance properties (smoothness, sharpness, etc.), physical properties (impact resistance, adhesion, scratch resistance, recoating properties, etc.), weather resistance, ultraviolet resistance, and chemical properties (acid rain resistance, solvent resistance) This is a problem in that the properties are inferior. Among these problems, in particular, acid rain resistance, solvent resistance and abrasion resistance are problems.

The powder coating technique is disclosed, for example, in US Pat. No. 3,845,016 (Labana et al.), US Pat. No. 3,919,347, and JP-A-5-112743. After coating a substrate (base) with a thermosetting powder coating containing an acrylic polymer having a glycidyl group as a resin component and dicarboxylic acid or polycarboxylic anhydride as a curing agent component, There is known a technique of forming a coating film on a substrate (base) by curing. However, cured coating films obtained by these techniques have excellent appearance characteristics (smoothness), but are particularly inferior in acid rain resistance, solvent resistance and scratch resistance.

[0008] As another improved technique for solving the problems of the above-mentioned known techniques, for example, US Patent No. 4,877,8
No. 37 (Reising et al.)
Research and development for improving the surface of a coating film by introducing a silicone compound having a reactive functional group such as a silanol group or an alkoxysilyl group into a resin component of a powder coating composition has been promoted. However, this powder coating composition,
Due to the presence of highly reactive silanol groups and alkoxysilyl groups in the silicone compound, the storage stability of the paint is significantly poor.

Japanese Patent Publication No. 3-43311 discloses a powder coating comprising a vinyl copolymer containing a glycidyl group-containing vinyl monomer, a silicon-containing vinyl monomer and other monomers, and an aliphatic dibasic acid. A composition is disclosed. The silicon-containing vinyl monomer used in this composition has a highly reactive functional group such as an alkoxysilyl group in addition to the vinyl polymerizable unsaturated double bond, and has only one silicon atom in one molecule. Compound. Although the coating film obtained from this powder coating composition has excellent smoothness of the coating film, it has a highly reactive functional group other than the unsaturated double bond in the silicon-containing vinyl monomer. Since the content of silicon in one molecule is small, the storage stability of the coating, the acid rain resistance and the solvent resistance of the coating film are inferior.

Japanese Patent Publication No. 09-505847 discloses a powder coating suitable for coating a vehicle body, characterized by using a specific epoxide group-containing polyacrylate resin as a binder. Techniques are disclosed. This powder coating is formed using an epoxide group-containing polyacrylate resin obtained by polymerizing the following components (a) to (d) as a binder. (A) an ethylenically unsaturated monomer containing at least one epoxide group in the molecule or a mixture thereof;
(B) an aliphatic or cycloaliphatic ester of (meth) acrylic acid or a mixture thereof 5.00 to 84.9% by weight, (c) statistically, at least 1% per molecule. Polymerizable ethylenically unsaturated groups and at least two general formulas: (—SiR ¹ R ² —O
-) [R ¹ and R ² are the same or different and are C1 to C8
An aliphatic or cycloaliphatic group or an optionally substituted phenyl group. An ethylenically unsaturated compound having the structural unit of 0.01 to 4.99% by weight, and
(D) 5.0 to 84.99% by weight of an ethylenically unsaturated monomer different from a, b and c or a mixture thereof.

In the technique relating to powder coating disclosed in Japanese Patent Application Laid-Open No. 09-505847, an ethylenically unsaturated polysiloxane macromonomer is combined with another vinyl monomer as a resin-forming component constituting a powder coating composition. It is characterized in that a silicone-modified epoxide group-containing polyacrylate resin is produced by copolymerization.

In this technique, it is essential to use an ethylenically unsaturated polysiloxane macromonomer. In the method for producing a two-layer coating on the surface of a substrate using the powder coating, (1) A colored base paint is applied to the surface of a substrate, and (2) Step (1)
(3) applying a transparent powder coating containing an epoxide group-containing polyacrylate resin as a binder on the base coating thus obtained; 4) It discloses that the base coating is baked together with the transparent powder coating. In this technology, although the adhesion between the base coat and the top coat when baking a powder coating on the base coating film is excellent, the recoating property of the top (clear) coats, that is, the powder coating is applied and baked. The correlation adhesion when a powder paint is baked on the baked coating film is not always good.

JP-B-3-45111 discloses (A) 100 parts by weight of a thermosetting resin, and (B) a glycidyl group-containing silicon-based material having a number average molecular weight of 150 or more and having no vinyl polymerizable unsaturated bond. A thermosetting resin composition containing 0.01 to 10 parts by weight of an additive as an essential component is disclosed.

Japanese Patent Publication No. 4-70331 discloses a thermosetting resin selected from the group consisting of polyester, epoxy resin and vinyl polymer or its resin-forming component, and the weight of these resins or resin-forming component. Reacting a silicon compound having no vinyl polymerizable unsaturated bond in a range of 0.01 to 30% based on A method for producing a resin is disclosed.

[0015] Japanese Patent Publication No. 3-45111 and Japanese Patent Publication No. 4
In the technology disclosed in JP-A-70331, although the appearance (smoothness) of the coating film is excellent, a highly reactive silane-based compound is used in the molecule of the silicon-containing compound. Inferiority (solid phase resistance),
In addition, since the content of silicon in one molecule is small,
Improvements in acid resistance and scratch resistance of the coating film were insufficient.

Japanese Unexamined Patent Publication No. 9-241538 discloses a copolymer in which an organopolysiloxane and an acrylic polymer are bonded in a graft or block form, and an epoxy group is added to a side chain of the acrylic polymer in the copolymer. A powder containing a silicone / acryl-graft copolymer as a main component, containing one or more groups selected from a hydroxyl group and a carboxyl group, and having a glass transition point of 45 ° C. or higher. A body paint is disclosed.

In this technique, the following points are disclosed. (1) A radically polymerizable polysiloxane or an organopolysiloxane having an SH group in a molecule is selected as the organopolysiloxane, and a graft or block copolymer is used. (2) The amount of the organopolysiloxane used is at least 5% by weight or more in the copolymer.

However, when the organopolysiloxane compound is used in an amount as disclosed in this technique, the transparency and clarity of the coating film when formed into a clear coat are reduced, and the undercoat coating film of the coating film is reduced. Adhesion and topcoat recoatability are inferior.

In European Patent Publication No. 275051,
A powder coating containing a polyacrylate resin produced by polymerizing an ethylenically unsaturated monomer in the presence of a silicone resin as a binder is disclosed. However, a large amount of the silicone resin described here causes a decrease in transparency and clarity when formed into a clear coat, a decrease in adhesion to an undercoat film, and a decrease in recoatability between top coats.

Summarizing the above-mentioned various problems, any of the following points (i) to (iv) was particularly problematic in the prior art relating to thermosetting powder coating compositions containing silicone compounds. . (I) When a silicone compound is frequently used in the production of a coating composition or a resin component, when a clear coat is used, the transparency and clarity of the coating film are poor, and the adhesion to the undercoat film and the recoating of the topcoat film are performed. Poor nature. Also, the equipment used for the production of coating compositions and resin components is significantly soiled by large amounts of silicone compounds. Further, the silicone compound remaining in the apparatus has a great adverse effect on other coating compositions or resin components, and may particularly deteriorate the appearance of the coating film. (Ii) Regarding the formation of a coating film, the coating film is likely to be repelled or repelled on a substrate (base), resulting in incomplete coating. (Iii) It is difficult to simultaneously exhibit excellent performance with respect to coating properties such as appearance properties, physical properties, weather resistance, ultraviolet resistance, and chemical properties. (Iv) The storage stability of the coating composition is poor.

[0021]

An object of the present invention is to solve the above problems (i) to (iv) in the conventional powder coating technology. Specifically, the object of the present invention is to
(I) improving the compatibility during preparation of the coating composition and preventing contamination during production; (ii) improving the complete coverage of the coating film on a substrate (substrate); and (iii) thermosetting. Appearance properties (smoothness, sharpness, etc.), physical properties (scratch resistance, recoating properties, etc.), weather resistance, UV resistance, and chemical properties (acid rain resistance, solvent resistance) And the like, and at the same time, exhibit excellent performance, and particularly, remarkably improve acid rain resistance, recoating property, solvent resistance, and scratch resistance, and (iv) the coating composition. An object of the present invention is to provide a thermosetting powder coating composition for a top coat capable of improving storage stability.

[0022]

The object of the present invention is to provide a monomer (a1) having at least one radically polymerizable unsaturated bond and at least one epoxy group in one molecule, and one monomer in one molecule. Having at least one radically polymerizable unsaturated bond and having no epoxy group (a
100 parts by weight of an acrylic copolymer (A) obtained by polymerization in a reaction system containing 2), and at least one functional group and at least two silicon atoms in one molecule;
Further, 0.01 to 2.0 parts by weight of an organically modified polysiloxane (B) having no radical polymerizable unsaturated bond is contained, and the component (B) is partially or wholly contained in the component (A). This is achieved by a thermosetting powder coating composition for a top coat, which is contained in a state of reacting with or binding to the whole or in an unreacted state.

In contrast to the prior art, the thermosetting powder coating composition of the present invention has, as a polysiloxane compound, a functional group but no radically polymerizable unsaturated bond and a silicon atom. The organically modified polysiloxane (B) having a number of 2 or more is added in a small amount in a specific range.

When a small amount of the organically modified polysiloxane (B) having such a specific structure is used, the organically modified polysiloxane (B) is uniformly crosslinked and maintained throughout the cured coating film, and as a result, a coating film having excellent properties is formed. And storage stability of the paint is not impaired.

The organically modified polysiloxane (B) having the specific structure may be contained in an unreacted state before the coating film is cured, that is, at the stage of the thermosetting powder coating composition, or A part thereof may be contained in a state of reacting with and binding to a resin component or the like. Therefore, the content of the organically modified polysiloxane (B) defined in the present invention is 0.1%.
The amount of 01 to 2.0 parts by weight indicates the total amount including the organically modified polysiloxane (B) in a bound state.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

[Acrylic Copolymer (A)] The acrylic copolymer (A) used in the present invention is a single copolymer having at least one radically polymerizable unsaturated bond and at least one epoxy group in one molecule. Obtained by polymerization in a reaction system containing the monomer (a1) and a monomer (a2) having at least one radically polymerizable unsaturated bond in one molecule and having no epoxy group. It is a copolymer.

[Monomer (a1)] The monomer (a1) is a monomer having at least one radically polymerizable unsaturated bond and at least one epoxy group in one molecule. There is no particular limitation. The epoxy group of the monomer (a1) remains after the formation of the acrylic copolymer (A), and contributes to the curing of the coating film by a crosslinking reaction with the functional group of the curing agent (C).

Specific examples of the monomer (a1) include glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, N-glycidyl (meth) acrylamide, allyl glycidyl ether, glycidyl vinyl sulfonate, , 4-epoxycyclohexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and the like. Of these, glycidyl (meth) acrylate is preferred,
Glycidyl methacrylate is more preferred. They are,
A single type or a combination of two or more types can be used.

[Monomer (a2)] The monomer (a2) is a monomer having at least one radically polymerizable unsaturated bond in one molecule and having no epoxy group. If there is, there is no particular limitation. In general, it is preferable that the resin does not have a reactive functional group of a type that contributes to the curing of the coating film through a crosslinking reaction with the reactive functional group of the curing agent (C).

Examples of the monomer (a2) include carboxylic acids, acid anhydrides, carboxylic esters, unsaturated hydrocarbons, and aromatic vinyl hydrocarbons having an unsaturated double bond.
Examples include nitriles and amides. Of these, carboxylic esters having a radically polymerizable unsaturated double bond are preferred.

Specific examples of such a monomer (a2) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. Acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, 2-ethyloctyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (Meth) acrylates such as (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, dimethylamino (meth) acrylate, isobornyl (meth) acrylate, and tricyclodecanyl (meth) acrylate Acid derivatives; maleic acid, fumaric acid,
Esters of dicarboxylic acids such as itaconic acid; amides such as (meth) acrylamide; α, β-unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid and maleic anhydride or anhydrides thereof; Can be These can be used alone or in combination of two or more.

Other specific examples of the monomer (a2) include aromatic vinyl hydrocarbons such as styrene, α-methylstyrene and vinyltoluene; vinyl chloride, vinylidene chloride, vinyl fluoride, monochlorotrifluoroethylene and the like. Halogenated ethylenically unsaturated monomers; nitriles such as (meth) acrylonitrile; aliphatic vinyl esters such as vinyl acetate; ethylene, propylene, α-olefins such as α-olefins having 4 to 20 carbon atoms; lauryl vinyl ether And unsaturated monomers such as alkyl vinyl ethers. These can be used alone or in combination of two or more.

The amount of the monomers (a1) and (a2) used is
15 to 60 parts by weight of the monomer (a1) and 40 to 85 parts by weight of the monomer (a2) are preferable, based on 100 parts by weight of the total of the monomer (a1) and the monomer (a2). Body (a1)
20 to 55 parts by weight and 45 to 80 parts by weight of the monomer (a2) are more preferable. The use of the monomer (a1) in an amount of at least the above-mentioned specific amount (preferably 15 parts by weight, more preferably 20 parts by weight) is particularly effective when the obtained coating film has acid rain resistance,
Excellent results are obtained in scratch resistance and solvent resistance. On the other hand, when the monomer (a1) is used in an amount not more than the above-mentioned specific amount (preferably 60 parts by weight, more preferably 55 parts by weight), the smoothness, sharpness, and It provides better results in storage stability of the coating composition and the like.

Of 40 to 85 parts by weight of the monomer (a2),
39 to 55 parts by weight of an alkyl group having 1 to 12 carbon atoms and / or
Alternatively, a (meth) acrylate ester having a cyclohexyl group is preferable. Use of such (meth) acrylic acid ester in an amount in the above range provides more excellent results in terms of hardness and weather resistance of the coating film.

When styrene is used as a part of the monomer (a2), the amount thereof depends on the amount of the monomer (a1) and the amount of the monomer (a).
1 to 30 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight in total of 2). in this case,
The total amount of the monomer (a2) is preferably from 40 to 85 parts by weight, more preferably from 50 to 80 parts by weight. Monomer (a2)
The advantage of using styrene as a part of the above is that it can impart more excellent gloss and smoothness to the coating film. Further, the use of styrene in an amount of not more than the above-mentioned specific amount (desirably 30 parts by weight, preferably 20 parts by weight) gives more excellent results in prevention of yellowing, weather resistance and the like of the obtained coating film. .

In general, when a small amount of a conjugated diene such as butadiene, a nitrile such as acrylonitrile, or an amide such as acrylamide is used as the monomer (a2) in a small amount, the coating film may have poor coloring and weather resistance. There is a tendency that no problem occurs, and carboxyl groups, acid anhydride groups,
When a small amount of a monomer having a group capable of reacting with an epoxy group such as an amino group is used, the acrylic copolymer component (A)
Tends to cause no problem in terms of gelation during the production of. Therefore, a small amount of these monomers [for example, the monomer (a
5 parts by weight or less based on the total weight of 1) and monomer (a2)], and is preferably used in combination with other monomers (a2).

It is preferable that the acrylic copolymer (A) is usually adjusted so that its glass transition point (Tg) is in the range of 30 to 100 ° C. The use of the acrylic copolymer (A) having a Tg of 30 ° C. or higher usually gives better results in storage stability and the like of the coating composition. On the other hand, the use of the acrylic copolymer (A) having a Tg of 100 ° C. or less usually prevents a decrease in the fluidity upon heating, and due to this, appearance properties such as smoothness of the obtained coating film and the like. For better results.

The Tg of the acrylic copolymer (A) is:
It can be calculated by Fox's formula. here,
Fox's formula is defined for each monomer forming a copolymer, based on the Tg of the homopolymer of the monomer.
This is for calculating the Tg of the copolymer, and details thereof are described in Bulletin of the American Physical Society, Series 2 (Bulletin of
he American Physical Soci
ety, Series 2) Vol. 1, No. 3, page 123 (1
956).

The Tg of various ethylenically unsaturated monomers, which is the basis for evaluating the Tg of the copolymer according to the Fox equation, can be found, for example, in Shinkobunbun, Vol. 7, Primer for Synthetic Resins for Paints (Kitaoka By Kyozo, Society for Polymer Publishing, Kyoto, 1
(974), pages 168 to 169, Table 10-2 (major raw material monomers of acrylic resin for paint) can be used.

All of the descriptions are incorporated into the disclosure of the present specification by explicitly citing the cited documents and the cited ranges, and by referring to the explicit cited ranges, the matters or disclosures described in the present specification are referred to. Thus, matters or disclosures that can be directly and uniquely derived by those skilled in the art.

The number average molecular weight (Mn) of the acrylic copolymer (A) is preferably from 1,000 to 10,000, and
500-4,000 is more preferred. The use of the acrylic copolymer (A) having Mn of the above-mentioned specific value (preferably 1,000, more preferably 1,500) or more results in more excellent storage stability of the coating composition and the like. Bring. On the other hand, the above specific value (preferably 10,000
Use of the acrylic copolymer (A) having an Mn of not more than (00, more preferably 4,000) gives more excellent results in appearance properties such as smoothness of the resulting coating film. Mn of the acrylic copolymer (A) can be measured by GPC using, for example, polystyrene as a standard.

The acrylic copolymer (A) can be prepared by a radical polymerization method such as a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method. In particular, the solution polymerization method is suitable.

Methods for adjusting the molecular weight of the acrylic copolymer (A) include mercaptans such as dodecyl mercaptan, disulfides such as dibenzoyl sulfide, and thioglycolic acid such as 2-ethylhexyl thioglycolate. -18, a chain transfer agent for halogenated hydrocarbons such as alkyl esters and carbon tetrabromide; an organic solvent having a large chain transfer effect such as isopropyl alcohol, isopropylbenzene, and toluene; Means can be used.

In the present invention, by adding an organically modified polysiloxane (B) described later during the production process of the acrylic copolymer (A), the organically modified polysiloxane is added to the acrylic copolymer (A). An acrylic copolymer containing an organically modified polysiloxane in which the siloxane (B) is dispersed in advance can be obtained. As a method for producing this organically modified polysiloxane-containing acrylic copolymer component, for example, (1) an organically modified polysiloxane (B) is previously dissolved in a monomer component, and bulk polymerization or solution polymerization is performed. In the case of solution polymerization, remove the organic solvent after polymerization,
(2) After performing the solution polymerization with an organic solvent, when removing the solvent, a method of adding the organically modified polysiloxane (B), uniformly dispersing the solvent, and then removing the organic solvent may be mentioned. However, during the production process of the acrylic copolymer (A), for example, an organically modified polysiloxane (B) having a reactive functional group capable of reacting with an epoxy group of the acrylic copolymer (A) is added. In this case, it is necessary to appropriately select the type, the functional group amount, the molecular weight, and the like of the reactive functional group of the organically modified polysiloxane (B) so as not to generate an undesired gel during the production process.

[Organically Modified Polysiloxane (B)] The organically modified polysiloxane (B) has at least one functional group and at least two silicon atoms in one molecule, and has a radical polymerizable property. The organic modified polysiloxane having no unsaturated bond is not particularly limited. This functional group is specifically a group reactive with the acrylic copolymer (A) or the curing agent (C).

The organic modified polysiloxane (B) has the following general formulas (I), (II), (III) and (IV)

[0047]

Embedded image [In the formula (1), X ¹ and X ² represent the following general formulas (a) to (f)

[0048]

Embedded image (In the formulas (a) to (f), Ra, Rb, Rc, Rd and Re
Is a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative,
Alternatively, it represents a hydrocarbon group having an ether bond and / or an ester bond, and Rf represents an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof. )
A group represented by any one of the above formulas, wherein R ¹ and R
² represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group or a derivative thereof, and R ^{3 to} R ⁸ represent an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof, n1 represents a number from 1 to 1,500. ]

[0049]

Embedded image [In the formula (II), X ³ is a group represented by any one of the general formulas (a) to (e), and R ^{9 to} R ¹⁵ are alkyl having 1 to 8 carbon atoms. R ¹⁶ represents a direct bond, having 1 to 8 carbon atoms.
Alkylene group, phenylene group, alkylene group derivative,
Represents a phenylene group derivative or a hydrocarbon group having an ether bond and / or an ester bond;
Represents a number of ~ 1,500. ]

[0050]

Embedded image [In the formula (III), X ⁴ is a group represented by any one of the general formulas (a) to (e), and R ^{17 to} R ²⁵ are alkyl having 1 to 8 carbon atoms. R ²⁶ represents a direct bond, having 1 to 8 carbon atoms.
Alkylene group, phenylene group, alkylene group derivative,
Represents a phenylene group derivative or a hydrocarbon group having an ether bond and / or an ester bond, and x1 is 1 to
The number of 1,300 and y1 represent the number of 1 to 200. ]

[0051]

Embedded image [In the formula (IV), X ⁵ , X ⁶ and X ⁷ are groups represented by any one of the above general formulas (a) to (e), and R ^{30 to} R ³⁶ are carbon atoms. Represents an alkyl group having 1 to 8 atoms, a phenyl group or a derivative thereof, wherein R ^{27 to} R ²⁹ are
Represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or a hydrocarbon group having an ether bond and / or an ester bond, and x2 represents a number of 1 to 1,300. , Y2 is 1 to
Represents the number 200. ] Is preferably at least one compound represented by any one of the above formulas. More specifically, the organically modified polysiloxane (B) has the following general formulas (V) to (XXVIII)

[0052]

Embedded image

[0053]

Embedded image

[0054]

Embedded image

[0055]

Embedded image

[0056]

Embedded image

[0057]

Embedded image

[0058]

Embedded image (In the formulas (V) to (XXVIII), R is each independently a direct bond, an alkylene group having 1 to 20 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or an ether bond and / or an ester. Represents a hydrocarbon group having a bond, n represents a number of 1 to 1,500 each independently, x represents a number of 1 to 1,300 each independently, and y represents a number of 1 to 200 each independently. Is more preferable.

R ^{3 to} R ^{8 of} the general formula (I), R ^{9 to} R ^{15 of} the general formula (II), R ^{17 to} R ²⁵ of the general formula (III), and R ³⁰ to R ^{30 of the} general formula (IV) R ³⁶ is a hydrocarbon group including an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof. As these, a phenyl group and a methyl group are preferable, and a methyl group is more preferable.

The range of the number of repeating units (n1, n2, x1 + y1, x2 + y2) in each of the general formulas (I) to (IV) is as defined in each formula. Is preferably 10, more preferably 100, and particularly preferably 500.

The epoxy equivalent of the organo-modified polysiloxanes of the general formulas (V) to (XII) is preferably from 200 to 5,000. The carboxyl equivalent of the organically modified polysiloxane of the general formulas (XIII) to (XVI) is 500 to
Preferably it is 5,000. The general formula (XVI
The organically modified polysiloxanes (I) to (XX) preferably have an —OH equivalent of 1,000 to 5,000. The organically modified polysiloxanes of the general formulas (XXI) to (XXVIII) preferably have an -NH ₂ equivalent of 500 to 10,000.

Commercially available organically modified polysiloxanes (B) represented by the general formula (I) include, for example, BY16-855, wherein X ¹ and X ² are groups represented by the general formula (a).
BY16-855B (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), KF-105, X-22
163A, X-22-163B, X-22-163C
(Both terminal manufactured by Shin-Etsu Chemical Co., Ltd., trade name).

Further, for example, X-22 and 169AS and X-22, wherein X ¹ and X ² are groups represented by the general formula (b)
169B (above, manufactured by Shin-Etsu Chemical Co., Ltd., trade name) and the like.

Also, for example, BY16-750 (both trade names, manufactured by Toray Dow Corning Silicone Co., Ltd.) and X-22, wherein X ¹ and X ² are groups represented by the general formula (c)
And carboxyl-modified dimethylpolysiloxane at both ends such as -162A and X-22-162C (all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

Also, for example, BY16-752 (both trade names, manufactured by Toray Dow Corning Silicone Co., Ltd.) and X-22, wherein X ¹ and X ² are groups represented by the general formula (d)
-169B (Shin-Etsu Chemical Co., Ltd., trade name)
Phenol-modified dimethylpolysiloxane at both ends.

Also, for example, BY16-853 and BY16-85, wherein X ¹ and X ² are groups represented by the general formula (e)
3B (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), X-22-161AS, X-22-16
Both terminal amino-modified dimethylpolysiloxanes such as 1A, X-22-161B, and KF-8012 (all, manufactured by Shin-Etsu Chemical Co., Ltd.).

As a commercially available product of the organo-modified polysiloxane (B) represented by the general formula (II), for example, X-22-173DX (wherein X ³ is a group represented by the general formula (a)) Shin-Etsu Chemical Co., Ltd., trade name) and one-terminal epoxy-modified dimethylpolysiloxane.

Commercially available organically modified polysiloxanes (B) represented by the general formula (III) include, for example, SF8411 and SF84 wherein X ⁴ is a group represented by the general formula (a).
13 (manufactured by Toray Dow Corning Silicone Co., Ltd., trade name), KF-1001, KF-101 (mandatory
Shin-Etsu Chemical Co., Ltd., trade name) and the like.

For example, BY16-839 (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), KF-102, wherein X ⁴ is a group represented by the general formula (b)
(Above, manufactured by Shin-Etsu Chemical Co., Ltd., trade name) and the like.

For example, SF8418 (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), X-22-3701, wherein X ⁴ is a group represented by the general formula (c)
E (above, manufactured by Shin-Etsu Chemical Co., Ltd., trade name) and the like.

Further, for example, X ⁴ is a group represented by the general formula (e), for example, BY16-828, BY16-8
59 (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), KF-864, KF-865, KF-8
68, KF8003 (Shin-Etsu Chemical Co., Ltd.
Side chain amino-modified dimethylpolysiloxane such as trade name).

The weight average molecular weight of the organically modified polysiloxane (B) is usually preferably from 500 to 100,000,
1,000 to 90,000 is more preferred. When the weight average molecular weight of the organically modified polysiloxane (B) is within the above range, the appearance of the resulting coating film is good, and the scratch resistance, acid resistance, and recoating property are good.

[Action mechanism of organically modified polysiloxane (B)] The action and effect of the organically modified polysiloxane (B) in the thermosetting powder coating composition used in the present invention are as follows. Guessed.

By heating, the organically modified polysiloxane (B)
By reacting the reactive functional group in the polymer with the reactive functional group of the acrylic copolymer (A) or the curing agent (C), the organically modified polysiloxane (B) is uniformly held in the cured coating film. ,
Due to the properties of the polysiloxane, a crosslinked coating film having particularly excellent solvent resistance, acid resistance, and scratch resistance can be formed. The organically modified polysiloxane (B) is cured by heating to 3
Since it is taken into the three-dimensional network structure, the compatibility is maintained and the polysiloxane skeleton is prevented from being extremely localized on the coating film surface.

Further, when the temperature is raised during baking, the reactive functional group in the organically modified polysiloxane (B) undergoes a cross-linking reaction with the acrylic copolymer (A) or the curing agent (C) to cause a 3 When incorporated into a three-dimensional network structure, internal plasticization occurs, which also lowers the melt viscosity of the coating and improves the smoothness of the coating.

When a polysiloxane having no functional group capable of reacting with the reactive functional group of the acrylic copolymer (A) or the curing agent (C) is used, the polysiloxane is an acrylic copolymer ( Since there is no reactive group capable of cross-linking with A) and the curing agent (C), the compatibility with the acrylic copolymer (A) and the curing agent (C) at the time of heat curing is insufficient. Although the resulting coating film is excellent in acid resistance, the appearance (transparency, smoothness), solvent resistance and recoating property of a clear coating film decrease, making it difficult to balance.

[Amount of Organic Modified Polysiloxane (B)] The amount of the organic modified polysiloxane (B) used in the present invention is 0.01 to 2 parts by weight based on 100 parts by weight of the acrylic copolymer (A). 0.0 parts by weight. If the amount exceeds 2.0 parts by weight, the coating film becomes cloudy, and the transparency and the sharpness tend to decrease. In addition, this usage amount is 0.
If the amount is less than 01 parts by weight, the resulting coating film has insufficient improvement in acid resistance and scratch resistance. The amount used is from 0.01 to 1.
More preferably, it is 0 parts by weight.

[Curing Agent (C)] The curing agent (C) used in the present invention is at least one selected from the group consisting of a polycarboxylic acid (c1) and a polycarboxylic anhydride (c2).
It is preferable that it is composed of various polycarboxylic acid compounds. Hereinafter, examples of the polycarboxylic acid (c1) and the polycarboxylic anhydride (c2) will be described.

[Polyvalent carboxylic acid (c1)] As the polyvalent carboxylic acid (c1), any of aliphatic, aromatic and alicyclic compounds can be used. Specific examples of the aromatic polycarboxylic acid include, for example, isophthalic acid and trimellitic acid, which can be used alone or in combination.
Specific examples of the alicyclic polycarboxylic acid include, for example, hexahydrophthalic acid, tetrahydrophthalic acid and the like, and these can be used alone or in combination. Further, a polyester resin having a carboxyl group or the like can also be used.

However, in the present invention, the use of an aliphatic polycarboxylic acid is preferred in view of coating properties such as smoothness and weather resistance.

As used herein, the term “aliphatic” includes not only aliphatic in a narrow sense but also alicyclic having a substantially low aromaticity. That is, the concept of the term "aliphatic" compound includes a group consisting of compounds having a substantially low aromaticity and having a divalent hydrocarbon group containing at least one carbon atom in the molecule. Specifically, not only an aliphatic group in a narrow sense, but also an alicyclic group having a substantially lower aromaticity, a group obtained by combining them, or a group formed by a hydroxyl group, nitrogen, sulfur, silicon, phosphorus, etc. It also includes a group consisting of compounds having a divalent residue to be bonded in the molecule, and more specifically, those described above include, for example, an alkyl group, a cycloalkyl group, an allyl group, an alkoxyl group,
It also includes a group consisting of compounds having a group substituted by a cycloalkoxyl group, an allyloxyl group, a halogen (F, Cl, Br, etc.) group in the molecule. By appropriately selecting these substituents, various properties (heat resistance, toughness, decomposability, strength properties, etc.) of the copolymer used in the present invention can be controlled. As used herein, the term "aliphatic" compound encompasses not only one kind of compound but also a combination of two or more kinds.

Hereinafter, examples of the aliphatic polycarboxylic acid will be described.

The aliphatic polycarboxylic acid is not particularly limited as long as it is an aliphatic compound having at least two carboxyl groups in the molecule, and one or more kinds can be used. Particularly, an aliphatic dicarboxylic acid having 8 to 20 carbon atoms is preferable.

Specific examples of the aliphatic polycarboxylic acid include:
And aliphatic dicarboxylic acids. Specific examples of the aliphatic dicarboxylic acid include, for example, sebacic acid, undecane diacid, dodecane diacid, brassic acid, eicosan 2
Acid, octadecane diacid and the like.
Sebacic acid, dodecane diacid, brassic acid, and eicosane diacid are preferred, and dodecane diacid is more preferred.
These can be used alone or in combination.

With respect to coating properties such as smoothness, impact resistance and weather resistance, the properties of the alicyclic polycarboxylic acid deteriorate as the degree of aromaticity increases.

[Polyhydric anhydride (c2)] As used herein, "anhydride", "anhydride group", "anhydride bond" and "polyanhydride"
The concept of the word "MARUZEN High Polymer Dictionary-C"
once Encyclopedia of Po
lymerScience and Engineer
ing (ed. by Kroschwitz, edited by Tatsuya Mita, Maruzen, Tokyo, 1994) ”, pages 996-998,“ Polyanhydride ”. As used herein, the terms "anhydride" and "anhydride" are mutually equivalent concepts, and the terms "anhydride" or "anhydride" used in the specification of the present application include: , Dictionary of Chemistry, Vol. 3 (published by Kyoritsu Shuppan, 1963), page 996, left column to page 997, right column.

In the present invention, a linear aliphatic polycarboxylic anhydride is preferred from the viewpoint of a bridging effect and the like. Hereinafter, examples of the aliphatic polycarboxylic acid anhydride will be described.

The aliphatic polycarboxylic anhydrides have substantially or no carboxyl groups in the molecule.
A linear or dimeric oligo- or polyaliphatic acid anhydride (anhydride), wherein at least two carboxyl groups and / or acid anhydride (anhydride) groups substantially exist in the molecule; It is not particularly limited as long as it has a compound, and one kind or two or more kinds can be used.

As used herein, the term “linear” includes not only linear but also linear or dimeric oligo- or polyaliphatic acid anhydrides (anhydrides). The case where a large ring having the same action is formed is also included.

Specific examples of the aliphatic polycarboxylic anhydride include a linear polycondensate obtained by dehydrating and condensing one or more aliphatic dicarboxylic acids. For example, certain linear polycondensates obtained by dehydrating and condensing one kind of aliphatic polycarboxylic acid can be represented by the following general formula.

HO- [OC (CH ₂ ) mCOO] n-H Here, m is a natural number of 1 or more and n is 2 or more, and preferably m is 30 or less.

The linear acid anhydride of the aliphatic dicarboxylic acid (c
Specific examples of 2) include, for example, a dehydrated linear condensate of the aliphatic polycarboxylic acid (c1). Among these, linear or dimeric oligo or polymers derived by dehydration condensation of at least one compound selected from the group consisting of sebacic acid, dodecane diacid, brassic acid, and eicosane diacid. Acid anhydrides are preferred, and dehydrated linear condensates of dodecane diacid are more preferred.

Other specific examples of the polycarboxylic anhydride (c2) include, for example, EP-A-695,77.
Modified polyanhydrides such as the polyisocyanate-modified dicarboxylic anhydride (poly) anhydride described in No. 1 and the polyol-modified polymeric polyanhydride described in European Patent Publication No. 299,420 can also be suitably used. it can.

As the polycarboxylic anhydride (c2), a commercially available polycarboxylic anhydride can also be suitably used.
Specific examples of these commercially available polycarboxylic anhydrides include:
For example, the product name “Addito” manufactured by Fianova Resin Co., Ltd.
l VXL1381 ”, a product name“ P manufactured by Okamura Oil Co., Ltd.
S-AH "and the like.

The polycarboxylic acid anhydride (c2) is preferably adjusted so that the melting point is in the range of 40 to 170 ° C. When the melting point of the polycarboxylic acid anhydride (c2) is in the above range, the appearance of the coating film is good, and the blocking property of the powder coating material is good.

[Cross-Link Formation by Aliphatic Dicarboxylic Anhydride] A cyclic anhydride of a polycarboxylic acid such as succinic anhydride or phthalic anhydride is reacted with an epoxy group in the acrylic copolymer (A). Since the anhydride has a high probability of reacting only with the epoxy ring of a specific glycidyl group in the molecule, the effect of bridging a plurality of acrylic copolymer (A) molecules is small.

On the other hand, when a (co) polycondensate of an aliphatic dicarboxylic acid is reacted with an epoxy group, the condensate is cleaved at the anhydride group to form a plurality of fragments.
Each reacts with an epoxy group in a separate acrylic copolymer (A) molecule to form a plurality of acrylic copolymers (A)
Since the effect of bridging molecules is exerted, chemical properties such as solvent resistance and acid resistance of the coating film are improved.

[Amount of Curing Agent (C)] The amount of the curing agent (C) used is preferably 5 to 60 parts by weight, and more preferably 15 to 50 parts by weight, based on 100 parts by weight of the acrylic copolymer (A). Parts are more preferred.

The equivalent ratio is such that one equivalent of the epoxy group of the acrylic copolymer (A) is equivalent to a functional group capable of undergoing a crosslinking reaction (such as a carboxyl group and / or an acid anhydride group) of the curing agent (C). ) Is preferably 0.5 to 1.5 equivalents,
More preferably, it is 0.7 to 1.2 equivalents.

When the amount of the curing agent (C) used and the equivalent ratio of the functional groups fall within these ranges, properties such as the appearance of the coating film, solvent resistance, and scratch resistance can be improved.

[Melting Point of Curing Agent (C)] The melting point of the curing agent (C) is preferably from 40 to 170 ° C. Melting point 4
The use of the curing agent (C) at a temperature of 0 ° C. or higher gives more excellent results in the storage stability of the powder coating and the like. on the other hand,
The use of the curing agent (C) having a melting point of 170 ° C. or less gives more excellent results in terms of the heat fluidity during baking of the paint, the smoothness of the obtained coating film, and the like.

[Additives] The powder coating composition of the present invention comprises:
Various additives that are usually added to paints can be added.

That is, an epoxy resin, a polyester resin,
A synthetic resin composition including polyamide or the like, or a natural resin or semi-synthetic resin composition including fibrin or a fibrin derivative can be blended to improve the appearance or physical properties of the coating film.

Further, according to the purpose, the powder coating composition of the present invention may optionally contain a curing catalyst, a pigment, a flow regulator, a thixotropic agent (thixotropic regulator), a charge regulator, a surface regulator, and a gloss-imparting agent. Further, additives such as an anti-blocking agent, a plasticizer, an ultraviolet absorber, an anti-bake agent (degassing agent), a coloring inhibitor, and an antioxidant may be blended. When used as a clear coat, a small amount of a pigment may be blended and colored to such an extent that complete opacity is not exhibited.

The “powder coating composition” generally refers to a composition containing a curing agent (C) and used as a powder coating itself. Not only that, but also the meaning of the resin component material for the powder coating before the curing agent (C) is added.

The method for producing the powder coating composition of the present invention (the method of compounding the composition) includes an acrylic copolymer (A), an organically modified polysiloxane (B) and, if desired, a curing agent ( The method is not particularly limited as long as C) can be blended in a desired ratio, and a known or publicly-known method can be employed. Further, in order to enhance the dispersibility of the organically modified polysiloxane (B), the organically modified polysiloxane (B) is melted in the acrylic copolymer (A) or the curing agent (C) and uniformly dispersed in advance. A method can also be adopted.

Specific examples of the method for producing the powder coating composition of the present invention include a kneading machine such as a roll machine, a kneader machine, a mixer (Banbury type, transfer type, etc.), a calendar machine, and an extruder. Combination, conditions of each process (temperature, melting or non-melting, rotation speed, vacuum atmosphere,
Inert gas atmosphere, etc.) is appropriately set, and a method of sufficiently uniform mixing is exemplified. Thereafter, a powder coating in a uniform fine powder state can be obtained using a pulverizer or the like. However, the present invention is not limited to these.

Further, as an embodiment of the compounding and kneading step of adding an additive and the like to the powder coating composition of the present invention, the acrylic copolymer (A), the organically modified polysiloxane (B) and the curing agent (C) are added. If necessary, additives such as an anti-blocking agent, a surface conditioner, a plasticizer, a charge control agent, a pigment, a filler, and an extender are added, and preferably in the range of 40 to 130 ° C, more preferably in the range of 60 to 130 ° C. Then, if the mixture is sufficiently melt-kneaded by a melt-kneading apparatus and cooled, the powder coating composition of the present invention containing the additive is obtained. Thereafter, by uniformly pulverizing to an appropriate particle size (usually 150 mesh or less), a powder coating in a fine powder state can be obtained. As the melt kneading apparatus, a heating roll machine, a heating kneader machine, an extruder (extruder) and the like can be usually used.

As a specific example of a method of applying a thermosetting powder coating comprising the composition of the present invention, for example, the thermosetting powder coating is applied by a coating method such as an electrostatic coating method or a fluid immersion method. There is a method in which the film is attached to an object, heated and thermally cured to form a coating film. The baking for this heat curing is usually about 100 ° C. to about 200 ° C., preferably about 12 ° C.
At a temperature of 0 ° C to about 180 ° C, usually about 10 to about 60
For a minute. By this baking, the acrylic copolymer (A), the organically modified polysiloxane (B), and the curing agent (C) undergo a crosslinking reaction. After the baking, if cooled to room temperature, a cured coating film having excellent properties can be obtained.

The thermosetting powder coating composition of the present invention has such excellent properties as described above, and thus is very useful for top coat applications such as automobile bodies or automobile parts. In particular, a method of overcoating an automobile body or an automobile part using a thermosetting powder coating comprising the composition of the present invention, comprising the composition of the present invention on an undercoat of a pigmented or metallic aqueous paint. It is very useful in a method of forming a coating film in which a thermosetting powder coating is electrostatically applied as a top coating and the base coating and the top coating are simultaneously baked.

[Concept of the word "derivative"] The concept of the word "derivative" used in the claims and the specification of the present application is based on the concept that a hydrogen atom of a specific compound is replaced by another atom or atomic group Z. Includes

Here, Z is a monovalent hydrocarbon group containing at least one carbon atom. More specifically, Z is an aliphatic group, an alicyclic group having a substantially low aromaticity, or a combination thereof. Or a residue in which these are bonded by a hydroxyl group, a carboxyl group, an amino group, nitrogen, silicon silicon, phosphorus, etc., and among these, particularly, those having an aliphatic structure in a narrow sense. Are preferred. Z is a group obtained by substituting, for example, a hydroxyl group, an alkyl group, a cycloalkyl group, an allyl group, an alkoxyl group, a cycloalkoxyl group, an allyloxyl group, a halogen (F, Cl, Br, etc.) group. You may.

By appropriately selecting these substituents, it is possible to control various properties of a coating film formed by the powder coating composition of the present invention.

[0114]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
The purpose of the present invention is to help the understanding of the present invention, and the description is not intended to limit the present invention. Further, “parts” and “%” used in the following description mean “parts by weight” and “% by weight”, respectively, unless otherwise specified.

[Production Examples 1-4: Production of Acrylic Copolymer] First, xylene was charged as an organic solvent into a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen inlet tube. The temperature was raised to the reflux temperature with stirring. The amount of xylene charged was 6 times the total weight of the monomers to be charged later.
The amount was equivalent to 6.7 parts. Next, while maintaining the system at the reflux temperature and stirring, the monomers shown in Table 1 were added to the monomers shown in Table 1 as a radical polymerization initiator, t-butyl-peroxy-2-ethylhexanoate (trade name: Perbutyl O, manufactured by NOF Corporation). Was dissolved in the amount shown in Table 1, and the mixed solution was added dropwise over 5 hours.
Parts by weight were added dropwise and the mixture was kept at 100 ° C. for 5 hours. The solvent of the obtained polymerization solution was removed under reduced pressure by heating to obtain a solid acrylic copolymer (Production Examples 1 to 4). The physical properties of the obtained acrylic copolymer (Production Examples 1 to 4) were analyzed by the following methods, and the results are shown in Table 1. Glass transition temperature (Tg): Based on the monomer composition,
It was calculated by the Fox equation. Number average molecular weight (Mn): Measured by GPC using polystyrene as a standard.

[Production Example 5: Production of acrylic copolymer]
As a monomer component, 0.1 part by weight of a polydimethylsiloxane macromonomer (trade name: Silicone Macromonomer AK-30, manufactured by Toa Gosei Co., Ltd.) is copolymerized with the monomer (a1) and the monomer (a2). A solid acrylic copolymer in which a silicone macromonomer was copolymerized (Production Example 5) was obtained in exactly the same manner as in Production Example 1 except that this was performed.

[Production Example 6: Production of acrylic copolymer]
Exactly the same procedure as in Production Example 1, except that 0.1 part by weight of γ-methacryloxypropyltrimethoxysilane was copolymerized with the monomer (a1) and the monomer (a2) as a monomer component. Thus, a solid acrylic copolymer (Production Example 6) in which a silicone monomer was copolymerized was obtained.

[Production Example 7: Production of an acrylic copolymer containing an organically modified polysiloxane] In a reactor similar to that used in Production Example 1, 66.7 parts by weight of xylene as an organic solvent was charged. As an organically modified polysiloxane, X-
0.1 part by weight of 22-163A (epoxy-modified dimethylpolysiloxane, epoxy equivalent: 950 g / eq., Manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was heated to the reflux temperature with stirring.

Next, while maintaining the system at the reflux temperature and stirring, 5.0 parts by weight of perbutyl O was dissolved in the monomers shown in Table 1, and the mixed solution was added dropwise over 5 hours.
Thereafter, 0.5 parts by weight of perbutyl O was added dropwise, and the mixture was kept at 100 ° C. for 5 hours. The solvent of the obtained polymerization solution was removed by heating under reduced pressure to obtain a solid organically modified polysiloxane-containing acrylic copolymer having a number average molecular weight of 2,800 (Production Example 7).

[Production Example 8: Production of acrylic copolymer containing organically modified polysiloxane] 100 parts by weight of xylene was charged into the same reactor as that used in Production Example 1, and Production Example 1 was prepared.
After 100 parts by weight of the acrylic copolymer obtained in the above was added and heated to 100 ° C. while stirring to dissolve uniformly,
Further, KF-80 is used as the organic modified polysiloxane (B).
12 (amino-modified dimethylpolysiloxane at both terminals,-
NH ₂ equivalent 2,300 g / eq., Manufactured by Shin-Etsu Chemical Co., Ltd., trade name) were added 0.1 part by weight, the temperature was raised to reflux temperature with stirring to uniformly disperse the organic modified polysiloxane.

Then, the solvent of the obtained resin solution was removed by heating under reduced pressure to obtain a solid acrylic copolymer modified with an organically modified polysiloxane having a number average molecular weight of 2900 (Production Example 8). .

[Production Example 9: Production of an acrylic copolymer modified with a silane compound] In a reactor similar to that used in Production Example 1, 100 parts by weight of xylene was charged.
After 100 parts by weight of the acrylic copolymer obtained in the above was added and heated to 100 ° C. while stirring to dissolve uniformly,
Further, γ-aminopropyltrimethoxysilane was added to 0.1 g.
1 part by weight, and the temperature was raised to the reflux temperature while stirring, and γ
-Aminopropyltrimethoxysilane was uniformly dispersed. Then, the solvent of the obtained resin solution was removed by heating under reduced pressure to obtain a solid acrylic copolymer containing γ-aminopropyltrimethoxysilane having a number average molecular weight of 2800 (Production Example 9). Was.

[Production Example 10: Production of dodecane diacid linear acid anhydride (c2)] Dodecane diacid and acetic anhydride (molar ratio =
1: 0.8) was charged into a reactor, heated to 150 ° C., and the resulting acetic acid was removed and reacted for 5 hours while reducing the pressure or the vacuum so that acetic anhydride did not flow out of the system. . Upon cooling immediately after the completion of the reaction, a white solid [dodecane 2
Acid linear acid anhydride (Production Example 10)]. The melting point of this compound was about 73 to about 82 ° C.

[Examples 1 to 14] The acrylic copolymer (A), the organically modified polysiloxane (B) and the curing agent (C) produced in Production Examples 1 to 4 were added in the weight ratio shown in Table 2. [Functional group of curing agent (C) / epoxy group in acrylic copolymer (A) = 1/1], 100 parts of acrylic copolymer (A) and curing agent (C) in total On the other hand, TI
Example 12: NUVIN 144 (trade name, light stabilizer, manufactured by Ciba Specialty Chemicals Co., Ltd.) and 1 part by weight of benzoin (anti-bake agent), and 2 parts by weight of TINUVIN 900 (manufactured by Ciba Specialty Chemicals, ultraviolet absorber). Only in parts No. to 14, 0.3 parts by weight of tin octoate (trade name Neostan U-28, curing catalyst, manufactured by Nitto Kasei Co., Ltd.) was added. After the above mixture was dry-blended uniformly using a Henschel mixer, using a twin-screw extruder PCM-30 (manufactured by Ikegai Kihan Co., Ltd.),
Cylinder temperature 110 ° C, screw rotation speed 20
At 0 rpm, kneading was performed twice (two passes). After cooling the melt-kneaded material, the mixture was finely pulverized with a pulverizer, and the sections that passed through a 150-mesh sieve were collected to obtain thermosetting powder coatings (Examples 1 to 14).

[Examples 15 and 16] Except that the organically modified polysiloxane-containing acrylic copolymer obtained in Production Examples 7 and 8 and the curing agent (C) were blended at the blending ratio shown in Table 2, Thermosetting powder coatings (Examples 15 and 16) were obtained in exactly the same manner as in Example 1.

[Comparative Example 1] Except that no organically modified polysiloxane was used, the same procedure as in Example 1 was carried out.
A thermosetting powder coating (Comparative Example 1) was obtained.

[Comparative Example 2] A method was performed in exactly the same manner as in Example 2 except that the organically modified polysiloxane was not used.
A thermosetting powder coating (Comparative Example 2) was obtained.

[Comparative Example 3] Resim as a flow control agent
A thermosetting powder coating (Comparative Example 3) was obtained in exactly the same manner as in Comparative Example 1, except that 1 part by weight of ix RL-4 (trade name, manufactured by Mitsui Chemicals, Inc.) was added.

Comparative Example 4 Except that 5.0 parts by weight of X-22-3701E (trade name of Shin-Etsu Chemical Co., Ltd.) was used as the organically modified polysiloxane (B), the same as Example 1 was used. A thermosetting powder coating (Comparative Example 4) was obtained by the method.

Comparative Example 5 Instead of using the organically modified polysiloxane (B) within the scope of the present invention, SF8416 (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.), which is a dimethylpolysiloxane modified with a side chain alkyl, was used. 0.
A thermosetting powder coating material (Comparative Example 5) was obtained in exactly the same manner as in Example 1 except that 1 part by weight was used.

[Comparative Example 6] Instead of using the organically modified polysiloxane (B) within the scope of the present invention, KF9, which is a polydimethylsiloxane whose reactive functional group is not modified,
6H-10000 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.)
A thermosetting powder coating material (Comparative Example 6) was obtained in exactly the same manner as in Example 1 except that 0.1 part by weight of a viscosity at 25 ° C of 10,000 cst) was used.

Comparative Example 7 Example 1 was repeated except that 0.1 part by weight of γ-glycidoxypropyltrimethoxysilane was used instead of using the organically modified polysiloxane (B) within the scope of the present invention. A thermosetting powder coating composition (Comparative Example 7) was obtained in exactly the same manner as described above.

Comparative Example 8 Acrylic Copolymer 10 Copolymerized with Silicone Macromonomer Obtained in Production Example 5
A thermosetting powder coating material (Comparative Example 8) was obtained in exactly the same manner as in Example 1 except that 0 part by weight and 30.9 parts by weight of dodecane diacid were used as a curing agent.

[Comparative Example 9] 100 parts by weight of an acrylic copolymer obtained by copolymerizing the silicone monomer (γ-methacryloxypropyltrimethoxysilane) obtained in Production Example 6 and dodecane diacid as a curing agent Was used in the same manner as in Example 1 except for using 31.1 parts by weight of a thermosetting powder coating material (Comparative Example 9).

Comparative Example 10 100 parts by weight of the acrylic copolymer modified with γ-aminopropyltrimethoxysilane obtained in Production Example 9 and 31.0 parts by weight of dodecane diacid as a curing agent were used. Except for this, a thermosetting powder coating material (Comparative Example 10) was obtained in exactly the same manner as in Example 1.

[Evaluation of Examples and Comparative Examples] A polyester-melamine cross-linked black paint was applied to a zinc-phosphate-treated 0.8 mm-thick satin-finished steel sheet at a thickness of 20 μm, and then baked at 170 ° C. for 30 minutes. Thus, a base-treated steel sheet was prepared. The thermosetting powder coating prepared in each of Examples and Comparative Examples was electrostatically coated on the base-treated steel sheet so that the film thickness became 60 to 70 μm, and baked at 150 ° C. for 30 minutes. I got

The following evaluation was performed on the coated plate. Regarding the smoothness of the coating film, regarding the smoothness, the appearance of the coating film was evaluated by visual inspection. Very excellent ones were evaluated as ◎, excellent ones as 優 れ, slight unevenness as △, and poor ones as X. did. The sharpness of the coating film: Regarding the sharpness, the appearance of the coating film was evaluated by visual inspection. Very excellent ones were evaluated as excellent, good ones as good, slightly cloudy ones as poor, and poor ones. X. Gloss: Evaluated by a gloss meter measurement value (60 ° gloss). Solvent resistance: The coating film surface was rubbed reciprocally 50 times with a gauze impregnated with xylene, and then visually observed at the rubbing portion. ◎ indicates no trace, ○ indicates a slight trace,
Significantly marked as x. Acid resistance (acid rain resistance); spot 0.4 ml of 40 vol% sulfuric acid aqueous solution on the surface of the coating film, leave it in a dryer at 60 ° C for 20 minutes, wash and dry the spots, and surface state of the coating film Was visually observed. ◎ indicates no trace, ○ indicates a slight trace, Δ indicates a remarkable mark, and × indicates that the entire surface is etched. Abrasion resistance: A scratch test was conducted by rubbing the coating film surface with a brush using a 3% cleanser suspension, and gloss (20 ° gloss) was evaluated before and after friction to calculate a gloss retention. Those having a gloss retention of 60% or more are regarded as having extremely excellent scratch resistance.
A sample with less than 50% was rated as excellent, and a sample with less than 50% was rated as poor when the scratch resistance was insufficient. Weather resistance; Irradiated with QUV tester for 2,000 hours,
Before and after the irradiation, the glossiness at 20 ° was evaluated, and the 20 ° gloss retention was calculated. The gloss retention was calculated by the following equation.

Gloss retention [%] = (20 ° gloss after irradiation) ÷ (20 ° gloss before irradiation) × 100 The gloss retention was 80% or more in ◎, 70-80% in ○, 70% or less was evaluated as x. Storage stability of powder coating composition;
For 30 days. Thereafter, the powder coating composition was formed into a pellet of 10 mmφ and 0.3 g. The pellets were treated with zinc phosphate by 0.8 m.
3mm at 150 ° C.
Hold for 0 minutes. The heating fluidity (mm) at this time was measured. The pellets having a heating fluidity of 100 mm or more were rated as ○, those having a heating fluidity of 20 mm or more and less than 100 mm were rated as Δ, and those having a heating fluidity of less than 20 mm were rated as ×. Recoating property: A coated plate baked at 150 ° C. for 30 minutes is further baked at the same temperature for 30 minutes, and then the same powder coating used for forming a coating film on the coated plate is electrostatically coated. Baking was performed for 30 minutes. The test coating film was subjected to a 2 mm width, 10 × 10 grid adhesion test,
After the test, the number of squares remaining without peeling was indicated. When no peeling was observed, the value was 100, and it was determined that the coating film had good recoating properties. In the case of all peeling, it was 0, and it was determined that the recoating properties were insufficient.

Tables 3 to 5 show the evaluation results of these coating films. Examples 1-16 relate to compositions with different types and combinations of components within the scope of the present invention. Comparative Examples 1-1
0 is for comparison with the composition of the present invention, and relates to the composition of the types and combinations of the constituent elements which are out of the scope of the present invention.

As is clear from the evaluation results of Examples 1 to 16, the composition of the present invention simultaneously exhibited excellent performance for all of the evaluation items 1 to 6.

Comparative Examples 1 and 2 are examples of powder coating compositions in which the organically modified polysiloxane (B) was not used, and the coating films were inferior in smoothness, acid resistance and scratch resistance.

Comparative Example 3 is an example in which an acrylic-based flow control agent having a low Tg was used without using the organically modified silicone oil (B). Comparative Example 4, which is good on the other hand but does not sufficiently improve the acid resistance and scratch resistance of the coating film, is an example in which the organically modified polysiloxane (B) is heavily used in an amount outside the range of the present invention.
In this case, the solvent resistance and recoating property of the coating film are poor.

Comparative Examples 5 and 6 are examples using a polysiloxane having no reactive functional group outside the scope of the present invention. In this case, the appearance, scratch resistance, acid resistance and recoating of the coating film were evaluated. Poor nature.

Comparative Example 7 is an example in which 0.1 part by weight of γ-glycidoxypropyltrimethoxysilane was added instead of using the organically modified polysiloxane (B) within the scope of the present invention. Poor acid resistance and abrasion resistance of the coating film, and poor storage stability of the powder coating.

Comparative Example 8 is an example in which an acrylic copolymer obtained by copolymerizing a silicone macromonomer was used. In this case, the recoating property of the coating film was not sufficiently improved.

Comparative Example 9 is an example in which an acrylic copolymer obtained by copolymerizing a silicone monomer (γ-methacryloxypropyltrimethoxysilane) was used. In this case, the scratch resistance of the coating film was reduced. Poor acid resistance and poor storage stability of paint.

Comparative Example 10 is an example in which an acrylic copolymer modified with γ-aminopropyltrimethoxysilane was used. In this case, the scratch resistance and acid resistance of the coating film were improved.
Poor storage stability of paint.

[0148]

[Table 1] -Monomer (a1) GMA; Glycidyl methacrylate-Monomer (a2) ST; Styrene, MMA; Methyl methacrylate, nBMA; n-butyl methacrylate, 2EHMA; 2-ethylhexyl methacrylate-Polymerization initiator PB-O; t -Butyl peroxy-2-ethylhexanoate -Silicone macromonomer AK-30; Silicone macromonomer AK-30 (manufactured by Toagosei Co., Ltd., trade name, Mn = 30,000) -Silicon-containing monomer γ-MPMS Γ-methacryloxypropyltrimethoxy silane

[0149]

[Table 2] X-22-3701E; side-chain carboxyl-modified dimethylpolysiloxane (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) SF8411: side-chain epoxy-modified dimethyl polysiloxane (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.) BY16 -750; Carboxy-terminal-modified dimethylpolysiloxane (trade name, manufactured by Dow Corning Toray Silicone Co., Ltd.) KF102: Side chain alicyclic epoxy-modified dimethylpolysiloxane (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) X-22 173DX; one-terminal epoxy-modified dimethylpolysiloxane (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) ・ KF8012; both-terminal amino-modified dimethyl polysiloxane (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) ・ DDA: dodecane diacid ・ VXL1381 Additol VXL1 81 (Vier Nova Resins Co., Ltd., trade name, aliphatic polyanhydrides) · LS2125; Crelan LS2125 (Bayer Corp., trade name, urethane-modified polyacid anhydride)

[0150]

[Table 3]

[0151]

[Table 4]

[0152]

[Table 5]

[0153]

As described above, according to the present invention,
(I) improving the compatibility during preparation of the coating composition and preventing contamination during production; (ii) improving the complete coverage of the coating film on a substrate (substrate); and (iii) thermosetting. Appearance properties (smoothness, sharpness, etc.), physical properties (scratch resistance, recoating properties, etc.), weather resistance, UV resistance, and chemical properties (acid rain resistance, solvent resistance) And the like, and at the same time, exhibit excellent performance, and particularly, remarkably improve acid rain resistance, recoating property, solvent resistance, and scratch resistance, and (iv) the coating composition. A thermosetting powder coating composition for a top coat capable of improving storage stability can be provided.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 183/08 C09D 183/08 (72) Inventor Hiroyuki Sakayama 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Pref. Mitsui Chemicals Co., Ltd. (72) Inventor Tsuyoshi Matsumoto 1190 Kasama-cho, Sakae-ku, Yokohama City, Kanagawa Prefecture Inside Mitsui Chemicals, Inc.

Claims (19)

[Claims] 1. A monomer (a1) having at least one radically polymerizable unsaturated bond per molecule and at least one epoxy group, and at least one radically polymerizable per molecule 100 parts by weight of an acrylic copolymer (A) obtained by polymerization in a reaction system containing a monomer (a2) having an unsaturated bond and not having an epoxy group, and at least one molecule in one molecule. An organically modified polysiloxane (B) having one functional group and at least two silicon atoms and having no radically polymerizable unsaturated bond;
0 parts by weight, and the component (B) is used for a top coat, in which a part or all of the component (B) is contained in a state of reacting with and binding to the component (A) or in an unreacted state. Thermosetting powder coating composition. 2. A curing agent (C) comprising at least one polycarboxylic acid compound selected from the group consisting of polycarboxylic acids (c1) and polycarboxylic anhydrides (c2). The thermosetting powder coating composition according to claim 1, comprising 60 parts by weight. 3. The thermosetting powder according to claim 2, wherein the functional group of the organically modified polysiloxane (B) is a group reactive with the acrylic copolymer (A) or the curing agent (C). Body paint composition. 4. The thermosetting composition according to claim 2, wherein the component (B) is partially or wholly contained in a state of reacting with and bonding to the acrylic copolymer (A) or the component (C). Powder coating composition. 5. The thermosetting powder coating composition according to claim 1, wherein the component (B) is entirely contained in an unreacted state. 6. An organically modified polysiloxane (B) having the following general formula (I), (II), (III) or (IV): [In the formula (1), X ¹ and X ² represent the following general formulas (a) to (f): (In the formulas (a) to (f), Ra, Rb, Rc, Rd and Re
Is a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative,
Alternatively, it represents a hydrocarbon group having an ether bond and / or an ester bond, and Rf represents an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof. )
A group represented by any one of the above formulas, wherein R ¹ and R
² represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group or a derivative thereof, and R ^{3 to} R ⁸ represent an alkyl group having 1 to 8 carbon atoms, a phenyl group or a derivative thereof, n1 represents a number from 1 to 1,500. ] [In the formula (II), X ³ is a group represented by any one of the general formulas (a) to (e), and R ^{9 to} R ¹⁵ are alkyl having 1 to 8 carbon atoms. R ¹⁶ represents a direct bond, having 1 to 8 carbon atoms.
Alkylene group, phenylene group, alkylene group derivative,
Represents a phenylene group derivative or a hydrocarbon group having an ether bond and / or an ester bond;
Represents a number of ~ 1,500. ] [In the formula (III), X ⁴ is a group represented by any one of the general formulas (a) to (e), and R ^{17 to} R ²⁵ are alkyl having 1 to 8 carbon atoms. R ²⁶ represents a direct bond, having 1 to 8 carbon atoms.
Alkylene group, phenylene group, alkylene group derivative,
Represents a phenylene group derivative or a hydrocarbon group having an ether bond and / or an ester bond, and x1 is 1 to
The number of 1,300 and y1 represent the number of 1 to 200. ] [In the formula (IV), X ⁵ , X ⁶ and X ⁷ are groups represented by any one of the above general formulas (a) to (e), and R ^{30 to} R ³⁶ are carbon atoms. Represents an alkyl group having 1 to 8 atoms, a phenyl group or a derivative thereof, wherein R ^{27 to} R ²⁹ are
Represents a direct bond, an alkylene group having 1 to 8 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or a hydrocarbon group having an ether bond and / or an ester bond, and x2 represents a number of 1 to 1,300. , Y2 is 1 to
Represents the number 200. ] The thermosetting powder coating composition according to claim 1, comprising at least one kind of an organically modified polysiloxane represented by any one of the above formulas. 7. The organic modified polysiloxane (B) has the following general formula (V), (V ′), (VI), (VI ′), (VII),
(VII '), (VIII), (VIII'), (IX), (X), (X
I), (XII), (XIII), (XIV), (XV), (XVI),
(XVII), (XVIII), (XIX), (XX), (XXI), (X
XII), (XXIII), (XXIV), (XXV), (XXVI), (X
XVII) and (XXVIII) Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image (In the formulas (V) to (XXVIII), R is each independently a direct bond, an alkylene group having 1 to 20 carbon atoms, a phenylene group, an alkylene group derivative, a phenylene group derivative, or an ether bond and / or an ester. Represents a hydrocarbon group having a bond, n represents a number of 1 to 1,500 each independently, x represents a number of 1 to 1,300 each independently, and y represents a number of 1 to 200 each independently. The thermosetting powder coating composition according to claim 1, comprising at least one organically modified polysiloxane represented by any one of the formulas: 8. The organic modified polysiloxane represented by any one of the general formulas (V) to (XII),
The thermosetting powder coating composition of claim 7, having an epoxy equivalent of 5,000. 9. The method according to claim 7, wherein the organically modified polysiloxane having a carboxyl group represented by any one of formulas (XIII) to (XVI) has a carboxyl equivalent of 500 to 5,000. Curable powder coating composition. 10. The phenol-modified organically modified polysiloxane represented by any one of the general formulas (XVII) to (XX) has an —OH equivalent of 1,000 to 5,000. 7. The thermosetting powder coating composition according to 7. 11. The organically modified polysiloxane having an amino group represented by any one of the general formulas (XXI) to (XXVIII) has an equivalent of —NH _{2 of} 500 to 10,000. Thermosetting powder coating composition. 12. The organic modified polysiloxane (B) is used in an amount of 0.01 to 100 parts by weight of the acrylic copolymer (A).
The thermosetting powder coating composition according to claim 1, which contains 1.0 part by weight. 13. An acrylic copolymer (A) comprising 15 to 60 parts by weight of a monomer (a1) and 100 parts by weight of a total of a monomer (a1) and a monomer (a2); A copolymer obtained by polymerization in a reaction system containing 40 to 85 parts by weight of monomer (a2), wherein 40 to 85 parts by weight of monomer (a2) is 1 to 30 parts by weight of styrene, and The thermosetting powder coating composition according to claim 1, comprising 39 to 55 parts by weight of a (meth) acrylic acid ester having an alkyl group and / or a cyclohexyl group having 1 to 12 carbon atoms. 14. The thermosetting composition according to claim 1, wherein the monomer (a1) contains at least one monomer selected from the group consisting of glycidyl (meth) acrylate and β-methylglycidyl (meth) acrylate. Powder coating composition. 15. The crosslinkable functional group of the curing agent (C) is 0.5 to 1.5 equivalents to 1 equivalent of the epoxy group of the acrylic copolymer (A). Thermosetting powder coating composition. 16. The curing agent (C) has a melting point of 40 to 170 ° C.
The thermosetting powder coating composition according to claim 2, which is: 17. The polycarboxylic acid (c1) is an aliphatic dicarboxylic acid having 8 to 20 carbon atoms, and the polycarboxylic anhydride (c2) is an aliphatic dicarboxylic acid having 8 to 20 carbon atoms. The thermosetting powder coating composition according to claim 16, which is a linear dimer or more oligo or polyanhydride derived by dehydration condensation of the above. 18. A method for producing a thermosetting powder coating using the composition according to claim 1, comprising at least an acrylic copolymer (A) and an organically modified polysiloxane (B).
A method for producing a thermosetting powder coating material, comprising: a step of melt-kneading a raw material containing a material and a curing agent (C); and a step of cooling and pulverizing the melt-kneaded material. 19. The method for producing a thermosetting powder coating according to claim 18, wherein the melt-kneading step is performed at a temperature of 40 to 130 ° C.