JPH11279449A - Thermosetting powder coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having excellent storage stability and low-temperature meltability/curability in the case of forming a coating film as well as good characteristics and properties of coating film by compounding a specific copolymer component, a specific curing agent component and a thermally-latent cationic polymerization initiator. SOLUTION: This composition contains (A) a copolymer produced by the radical polymerization in a reaction system containing (i) a radical-polymerizable monomer containing a radical-polymerizable functional group and an epoxy group [preferably glycidyl (meth)acrylate] and (ii) a monomer having a radical- polymerizable functional group and free from epoxy group [preferably an ester of a primary or secondary alcohol and (meth)acrylic acid], (B) a curing agent component composed of a linear acid anhydride of an aliphatic polybasic carboxylic acid (preferably derived from adipic acid, etc.), and (C) a curing agent component composed of a thermally-latent cationic polymerization initiator (preferably p-t-butylbenzyltetrahydrothiophenium antimony hexafluoride, etc.).

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, sharpness, etc.), physical characteristics (scratch resistance, etc.), and weather resistance. Excellent paintability, chemical properties (acid resistance), and storage stability of paint.
The present invention relates to a thermosetting powder coating composition having low-melting / low-temperature curability.

[0002]

[Prior art] [Research and development trends and expectation for powder coatings in the technical field of coatings from the viewpoint of ecology etc.]
Solvent-type paints are used for coating objects, and paints satisfying various requirements have been developed and used for use in fields requiring strict quality such as for automobiles.

[0003] In recent years, in the technical field of paints, from the viewpoint of local or global environmental protection, occupational safety and environmental protection, fire and explosion prevention, and resource saving, etc., solvent paints have been replaced with powder paints. Changes have been expected. And, due to historical or social demands, as the expectations for higher functionality and diversification of powder coatings grow,
Higher film performance (eg, impact resistance, acid rain resistance, etc.) comparable to solvent-based paints has been required. However, even though the coating film performance required for powder coatings has become strict, it cannot be said that powder coatings that completely satisfy such requirements have always been put on the market.

[General technical background of powder coatings] Specific examples of conventional powder coatings include, for example, epoxy resin and polyester resin powder coatings mainly composed of bisphenol A. However, these have problems not only in weather resistance but also in resistance to acid rain, which has been a particular problem recently, and have problems in applications intended for outdoor use such as painting of automobile bodies. .

[Technical background of acrylic resin powder coating]
JP-A-49-34546 discloses a paint which is cured by a reaction between an acrylic resin component having a glycidyl group and a fatty acid dibasic acid as a curing agent component. However, the curing speed of the powder coating is not always sufficient, and high-temperature and long-time baking conditions are indispensable. And, the coating film formed from the powder coating material did not always have sufficient physical properties such as solvent resistance and adhesion.

Further, in such a technique which does not use a curing catalyst, a functional group (an acrylic resin component;
By increasing the amount of glycidyl group, curing agent component; carboxyl group), the cross-linking during coating film formation is improved,
Even if you intend to achieve low-temperature melting / low-temperature curing,
Problems similar to those described above and other problems have arisen.

[Acrylic resin-based powder coating containing a compound having an acid anhydride group as a curing agent]
The technique disclosed in No. 2 discloses a method of curing a copolymer composed of a system containing a monomer having 5 to 20% by weight of a glycidyl group as an acrylic resin component by curing a dicarboxylic acid or a linear acid anhydride. It is a method of crosslinking and curing using an agent. However, 20% by weight of a monomer having a glycidyl group is used.
In the case of a copolymer containing the following, the crosslinked density of the obtained coating film was insufficient, and the solvent resistance and the weather resistance were poor.

[0008] A number of researches and developments have been promoted for the purpose of solving the problems of the above-mentioned known techniques. US Patent 4,0
No. 91,048 and JP-B-58-2983 disclose a copolymer containing 5 to 20% by weight of a monomer having a glycidyl group, and a coating which is crosslinked and cured from an acid anhydride group. However, since these copolymers also use a copolymer containing 20% by weight or less of a monomer having a glycidyl group, the cross-linking density of the obtained coating film is insufficient, and the solvent resistance and weather resistance are not necessarily sufficient. Was. Also,
In particular, Japanese Patent Publication No. 58-2983 discloses a technique relating to a powder coating composition employing a cyclic acid anhydride (a compound having a cyclic acid anhydride group) as a curing agent. Here, the cyclic acid anhydride may be aromatic or alicyclic. However, when the above-mentioned cyclic acid anhydride is used as a curing agent component, there are problems with low compatibility between the resin component / curing agent component and low crosslinking formation efficiency between the resin component / curing agent component.

[Technical Background of Acrylic Resin Powder Coating Containing Curing Catalyst] Japanese Patent Application Laid-Open No. Hei 8-231893 discloses a glycidyl group-containing acrylic copolymer (A), an aliphatic polycarboxylic acid (B), and a fatty acid. Containing a polyhydric carboxylic acid linear anhydride (C) or a salt thereof (D) of a tertiary amine compound with an organic acid and / or a tertiary amine compound (E) having a melting point of 20 ° C. to 150 ° C. A curable powder coating composition is disclosed.

However, the present invention is not sufficient with respect to storage stability and low-temperature convenience, and as disclosed in Japanese Patent Application Laid-Open No. Hei 8-231893, aliphatic polycarboxylic acids coexist. When a salt of a tertiary amine compound and an organic acid and / or a tertiary amine compound having a melting point of 20 ° C. to 150 ° C. is used as a curing catalyst in the powder coating composition, a storage temperature of about 40 ° C. Under high temperature conditions, storage stability was not always sufficient.

JP-A-9-67530 discloses (A) a glycidyl group-containing vinyl resin, (B) an aliphatic dibasic acid,
(C) A thermosetting vinyl resin powder coating composition comprising a heat-latent cationic polymerization initiator as an essential component is disclosed. In this technique, a coating film obtained by crosslinking an aliphatic dibasic acid with the curing agent component (B) is not necessarily sufficient in the scratch resistance and solvent resistance of the coating film,
Even if an attempt is made to improve the curing properties by increasing the amount of the monomer component having a glycidyl group in the component (A), deterioration in the smoothness and gloss of the coating film will be caused. It is difficult to balance with.

JP-A-9-95644 discloses that a specific aromatic sulfonium salt having a catalytic action for ring-opening cationic polymerization of an epoxy group is added to an epoxy group compound.
A thermosetting coating composition having excellent storage stability, low-temperature curability and the like and excellent coating performance of a formed coating film is disclosed. There is no disclosure or description in the specification of using (aliphatic linear poly) acid anhydride. Further, when only an aromatic sulfonium salt having a cation ring-opening catalytic action is added to the epoxy compound and cured by heating, problems occur in the appearance and weather resistance of the coating film.

[0013]

SUMMARY OF THE INVENTION In view of the problems of the prior art, the present inventors have found that it is difficult to achieve by the prior art. Excellent low-temperature meltability / low-temperature curability at the time of coating film formation It is an object of the present invention to provide a thermosetting powder coating composition capable of simultaneously exhibiting excellent coating film properties and physical properties after coating film formation. .

A further object of the present invention is to provide a method for producing such an excellent thermosetting powder coating material.

[0015]

The present invention provides the following [1].
To [8].

[1] A thermosetting powder coating composition comprising a copolymer component (A), a curing agent component (B), and a curing catalyst component (C), wherein the copolymer component (A) A)
(A1) at least one kind of radically polymerizable monomer having at least one radically polymerizable functional group and at least one epoxy group in one molecule, and (a2) 1
A copolymer obtained by radical polymerization in a reaction system containing at least one monomer having no at least one radical polymerizable functional group in the molecule and not having an epoxy group,
The curing agent component (B) is an aliphatic polycarboxylic carboxylic acid linear anhydride, and the curing catalyst component (C) is a thermolatent cationic polymerization initiator. Body paint composition.

[2] The curing catalyst component (C) is used with respect to 100 parts by weight of the total of the components (A) and (B).
The thermosetting powder coating composition according to [1], comprising 0.01 to 5 parts by weight.

[3] The thermosetting powder coating composition according to [1] or [2], wherein the component (C) is an aromatic sulfonium salt.

[4] The equivalent ratio of the functional group present in the molecule of the component (A) to the functional group present in the molecule of the component (B) is the epoxy group 1 present in the molecule of the component (A). The total of the carboxyl group and the acid anhydride (anhydride) group present in the molecule of the component (B) is 0.5 to 2.
The thermosetting powder coating composition according to any one of [1] to [3], which becomes 0 equivalent.

[5] The aliphatic polycarboxylic acid linear anhydrides are (b-1) adipic acid, (b-2) sebacic acid, (b-3) eicosane diacid and (b-4). )
The thermosetting powder coating composition according to any one of claims 1 to 4, wherein the thermosetting powder coating composition is a compound derived by dehydration condensation from at least one compound selected from the group consisting of dodecane diacid.

[6] The thermosetting powder coating composition according to any one of [1] to [5], wherein the aliphatic polycarboxylic acid linear anhydride has a melting point of 40 to 150 ° C.

[7] A method for producing a thermosetting powder coating using the composition according to [1], comprising at least a component (A), a component (B) and a component (C). A method for producing a thermosetting powder coating, comprising: a step of melt-kneading raw materials; and a step of cooling and pulverizing the melt-kneaded material.

[8] The melt-kneading step is performed at 40 to 130 ° C.
The method for producing a thermosetting powder coating according to [7], wherein the method is performed at a temperature of:

A further object of the present invention is a method for producing a thermosetting powder coating using the above-mentioned composition of the present invention, wherein at least the copolymer component (A),
A method for producing a thermosetting powder coating, comprising: a step of melt-kneading a raw material containing a curing agent component (B) and a curing catalyst component (C); and a step of cooling and pulverizing the melt-kneaded product. Can be achieved by

The present invention is characterized in that the above components (A), (B) and (C) are used in combination, and that the specific curing agent component (B)
And the use of a heat-latent cationic polymerization initiator component (C) as a curing catalyst component (C), and by controlling these compositions and composition ratios, A high degree of action and effect can be exhibited.

The thermosetting powder coating composition of the present invention can exhibit the above-mentioned excellent performance even when applied and baked on an aqueous undercoat.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION [Component (A)] In the claims and the specification of the present application, the term "copolymer" means a random copolymer, an alternating copolymer, a block copolymer, a graft copolymer or the like. And the polymer may be linear, macrocyclic,
Any of a branched shape, a star shape, a three-dimensional mesh shape and the like may be used.

[Monomer (a-1)] In the present invention, the monomer (a-1) to be copolymerized in the copolymer component (A) substantially has an epoxy group and a radical polymerizable functional group. The compound is not particularly limited as long as it has a specific combination.

Specific examples of the monomer (a-1) include, for example, glycidyl acrylate, glycidyl methacrylate, β-methyl glycidyl acrylate, β-methyl glycidyl methacrylate, N-glycidyl acrylamide, allyl glycidyl ether, vinyl Glycidyl sulfonate and the like can be mentioned. The monomer (a-
Cyclomer M-100 as other specific examples of 1)
Monomers having an alicyclic epoxy group such as Cyclomer M-101 and Cyclomer A-200 (trade names, manufactured by Daicel Petrochemical Industries, Ltd.) and the like. These monomers (a-1) can be used alone or in combination of two or more. Among these monomers (a-1), glycidyl acrylate and glycidyl methacrylate are preferred.

The amount of the monomer (a-1) used is
20 to 60 parts by weight, more preferably 25 to 50 parts by weight, based on 100 parts by weight of -1) and the monomer (a-2) in total. When the amount of the monomer (a-1) exceeds 20 parts by weight, the resulting coating film has a high crosslinking density and has good coating characteristics such as impact resistance, scratch resistance, and solvent resistance, which are preferable. When the amount of the monomer (a-1) is at most 60 parts by weight, the appearance of the coating film such as smoothness and sharpness will be good, which is preferable.

[Monomer (a-2)] Copolymer component (A)
(A-2) which is copolymerized with (a-1) in the above, has at least one radically polymerizable functional group in one molecule,
At least one monomer having no epoxy group is used.

Specific examples of the monomer (a-2) include, for example, unsaturated carboxylic esters, unsaturated hydrocarbons,
Nitriles, amides, etc., among these,
Unsaturated carboxylic esters are preferred, and esters of primary or secondary alcohols with acrylic acid or methacrylic acid are more preferred.

Specific examples of esters of primary or secondary alcohols with acrylic acid or methacrylic acid include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, dodecyl Acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, isobornyl acrylate, tricyclodecanyl acrylate, benzyl acrylate, phenyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate,
1,4-butanediol monoacrylate, acrylic acid derivatives such as dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate,
Lauryl methacrylate, stearyl methacrylate,
Methacrylic acid such as cyclohexyl methacrylate, isobornyl methacrylate, tricyclodecanyl methacrylate, benzyl methacrylate, phenyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, 1,4-butanediol monomethacrylate, dimethylaminoethyl methacrylate Derivatives, vinyl acetate, vinyl esters such as vinyl propionate, maleic acid, dicarboxylic esters with itaconic acid, etc., styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, vinylanisole, vinylnaphthalene,
Aromatic vinyls such as divinylbenzene, chlorostyrene, etc., nitriles such as acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinylamide, N-methylolacrylamide, N-methylolmethacrylamide, diacetoneacrylamide, diacetonemethacrylamide, etc. Amides, vinyl chloride,
Vinylidene chloride, vinyl fluoride, monochlorotrifluoroethylene, tetrafluoroethylene, halogenated ethylenically unsaturated monomers such as chloroprene, ethylene, propylene, isoprene, butadiene, α-olefins having 4 to 20 carbon atoms and Examples include ethylenically unsaturated monomers including conjugated dienes, alkyl vinyl ethers such as lauryl vinyl ether, and nitrogen-containing vinyls such as vinyl pyrrolidone and 4-vinyl pyrrolidone. These may be used alone or in combination of two or more. Can be used.

In general, when an aromatic vinyl such as styrene or a conjugated diene such as butadiene is used as the monomer (a-2), nitriles such as acrylonitrile may be used in view of the weather resistance of the coating film. When using an amide such as acrylamide, a monomer component capable of reacting with an epoxy group such as a carboxyl group, an acid anhydride group, and an amino group in the molecule in terms of coloring and appearance of the coating film, and If you use a small amount,
In order to avoid a problem in gelation during the production of the copolymer component (A), these monomers are used in a small amount (for example, (a-1)
(30 parts by weight or less, based on the total weight of (a-2)) and (a-2)), and is preferably used in combination with the other (a-2) monomers.

The amount of the monomer (a-2) used is
1 to 40 parts by weight, preferably 50 to 75 parts by weight, based on 100 parts by weight of the total of -1) and the monomer (a-2).

The calculated glass transition point (Tg) of the copolymer component (A) obtained by the Fox equation is from about 20 to about 100 ° C.
Is preferable, about 30 to about 90 ° C. is more preferable, and about 5 to about 90 ° C. is preferable.
0 to about 80C is particularly preferred. When the Tg is 20 ° C. or higher, the storage stability of the coating composition tends to be improved.

[Calculated Glass Transition Point—Evaluation of Glass Transition Point (Tg) of Heteropolymer] The glass transition point (Tg) of a polymer having a specific monomer composition can be calculated by the Fox equation. it can. Here, the Fox equation is for calculating the Tg of the copolymer based on the Tg of the homopolymer of the monomer for each monomer forming the copolymer, For more information, see Bullet
in of the American Physic
al Society, Series2 Volume 1 ・ 3 ・
P. 123 (1956).

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 in, for example, Shin Kobunko Bunko, Vol. 7, Introduction to Synthetic Resins for Paints (Kitaoka By Kyozo, Polymer Publishing Association, Kyoto, 197
(4 years) The numerical values described in Table 10-2 (main raw material monomers of acrylic resin for paint) on pages 168 to 169 can be adopted.

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

[Method of Synthesizing Copolymer Component (A)] The method of synthesizing the copolymer component (A) is not particularly limited as long as it has substantially desired properties.

The copolymer component (A) can be synthesized by a known and publicly used ordinary method. For example, it can be prepared by a radical polymerization method including a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a bulk polymerization method. In particular, a solution polymerization method is suitably used.

[Molecular Weight of Copolymer Component (A)] Methods for adjusting the molecular weight of the copolymer component (A) include mercaptans such as dodecyl mercaptan, disulfides such as dibenzoyl sulfide, and thioglycolic acid 2- Thioglycolic acid such as ethylhexyl has 1 to 1 carbon atoms.
18 alkyl esters, a chain transfer agent of halogenated hydrocarbons such as urea tetrabromide, isopropyl alcohol,
Means such as polymerization in the presence of an organic solvent having a large chain transfer effect such as isopropylbenzene and toluene can be used.

The number average molecular weight of the copolymer component (A) is preferably about 1,000 to about 20,000, and is preferably about 2,000 to 2,000.
About 10,000 is more preferred. Number average molecular weight is about 1.0
When it is at least 00, the storage stability of the coating composition is generally good and preferable. When the number average molecular weight is 10,000 or less, the finished appearance of the coating film is good and preferable. The number average molecular weight of the copolymer component (A) was evaluated by gel permeation chromatography (GPC) using polystyrene as a standard.

[Curing Agent Component (B)] In the present invention, the aliphatic polyhydric carboxylic acid linear anhydride is substantially a linear oligo- or polyaliphatic having a carboxyl group in the molecule. The acid anhydride (anhydride) is not particularly limited as long as it is a compound having at least two carboxyl groups and acid anhydride (anhydride) groups substantially present in the molecule. Can be used.

In some cases, aliphatic polycarboxylic acids such as aliphatic dicarboxylic acids may remain as impurities in the linear acid anhydride, but they may adversely affect the thermosetting powder coating composition. If there is no range, it may remain.

Preferably, the aliphatic polycarboxylic acid linear anhydride is prepared such that the melting point is in the range of about 40 to about 150 ° C. Generally, the aliphatic polyhydric carboxylic acid linear anhydride has a melting point of about 40 ° C. or higher, and the coating composition has good blocking resistance. Further, generally, the melting point of the aliphatic polycarboxylic acid linear anhydride is about 150 ° C. or less, and the coating has good heat fluidity, and the resulting coating film has good appearance properties such as smoothness. is there.

The aliphatic polycarboxylic acid linear anhydride is generally a polycarboxylic carboxylic acid linear anhydride and / or an aliphatic dihydric carboxylic acid represented by the following general formula (1). Is a linear acid anhydride. HO- [OC (CH2) mCOO] n-H (1) (m = 4 to 20, each of n ≧ 2 is a natural number.) The upper limit of n is preferably about 20.

Here, specific examples of the aliphatic polycarboxylic acid linear acid anhydride include, for example, succinic acid, adipic acid,
A linear condensate derived from at least one compound selected from aliphatic divalent carboxylic acids such as azelaic acid, sebacic acid, brassic acid, eicosane diacid and dodecane diacid by dehydration condensation is exemplified. Of these,
Adipic acid, sebacic acid, dodecane diacid, eicosane 2
Dehydration linear condensates of acids are more preferred.

In the present specification, the term "aliphatic" includes an alicyclic group having a low aromaticity, such as 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid. Linear acid anhydrides derived from alicyclic polycarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and norbornanedicarboxylic acid can also be used as the component (B).

As the aliphatic polycarboxylic acid linear acid anhydride, a linear acid anhydride derived by dehydration condensation of two or more kinds of aliphatic polycarboxylic acids can be used. As the aliphatic polycarboxylic acid linear acid anhydride, commercially available aliphatic polycarboxylic acid linear acid anhydrides can also be suitably used. These were confirmed to have the same effect as the aliphatic polycarboxylic acid linear acid anhydride synthesized by the present inventors.

Specific examples of these commercially available aliphatic polycarboxylic acid linear acid anhydrides include, for example, trade names “SL12-AH”, “PS-AH”, and “SL2” manufactured by Okamura Oil Co., Ltd.
0-AH ", a product name" Addi "manufactured by Fianova Resin Co., Ltd.
tol VXL1381 ". For example, the following (1) to (4) disclose the chemical properties and chemical structure of "Additol VXL1381" manufactured by Fianova Resin. All of those descriptions are incorporated as part of the disclosure of the present specification by explicitly citing the cited documents and the cited ranges, and are referred to from the matters or disclosures described in the application specification of the present invention by referring to the explicitly cited ranges. Thus, matters or disclosures that can be directly and uniquely derived by those skilled in the art.

[Acryic powder cle]
ar coat for automatic OE
M ", Schmidt, Holger. Powder Coat. What's Next
? , Int. Conf. , 13th (1993), P
aper 13, page 11. Paint Research Associate
n, Tedington, UK. Coden: 61S
ZAA.

"Auto assembly lin"
e coating with polyacrylat
e-based clear powder ", Fin
k, Dietmar and Schmidt, Holge
r. Kunthartz-Nachr. (1994), 3
0, pages 6-9. Coden: KUNADE; ISSN; 0170-06
93.

"Acrylic powder cl"
ear coat for automotoive
OEM ", Schmidt, Holger. Pittu
re Vernici Eur. (1994), 7
0, pages 5-10. Coden: PVEUEO.

[Aliphatic polycarboxylic acid linear acid anhydride]
The concept of the term "aliphatic polycarboxylic acid linear acid anhydride" includes "polymeric polyanhydride", "containing an acid anhydride group in a polymer skeleton, and containing a plurality of acid functional groups. Do
Polymeric polyanhydrides "," aliphatic polyanhydrides "
"Polyanhydrides of aliphatic carboxylic acids", "polyme"
ric polyhydridide "," polym
eric polyhydridide contai
ninganhydride links in
"the polymeric backbone" and "polyhydride of aliphat"
ic carboxyl acids "and the like.

When a cyclic acid anhydride, such as succinic anhydride or phthalic anhydride, is reacted with the copolymer component (A), the acid anhydride becomes a specific component in the copolymer component (A) molecule. Since there is a high probability of reacting only with the epoxy ring of the glycidyl group, the effect of bridging a plurality of copolymer component (A) molecules is small, and curing of the latent heat cationic polymerization initiator which is a curing catalyst component (C). Use of this compound is not preferred because of its small accelerating effect.

[Linear oligo or poly aliphatic acid anhydride (anhydride)] In the present specification, "linear"
The concept of the term includes not only the linear but also the case where the linear or dimeric oligo- or polyaliphatic acid anhydride forms a macrocycle. Here, “linear” has the opposite concept of “small ring”, but does not have the opposite concept of “branched”. Therefore, "aliphatic polycarboxylic acid linear acid anhydride" or "linear acid anhydride" is, to the last, the acid anhydride group is "small cyclic"
(7-membered ring or less), which are connected in a “linear” manner, and are not limited to linear ones, but include, for example, primary to high, such as macrocyclic, branched, and branched. It may have the following structure.

The terms "anhydride", "anhydride group", "anhydride linkage" and "polyanhydride" used in the specification of the present application include "MARUZ".
EN Polymer Dictionary-Concise Encyclop
edia of PolymerScience an
d Engineering (Kroschwitz
Ed., Translated by Tatsuta Mita, Maruzen, Tokyo, 1994) "・ 99
The concept of each word described in the section of “Polyanhydride” on pages 6 to 998 is also included.

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

In the early 1980's, when polyanhydride was actively researched and developed on biodegradable bio (medical) polymer materials and application of the materials to drug delivery systems, researchers at MIT were active. And came to the spotlight.

The aliphatic polycarboxylic acid linear acid anhydride can be synthesized, for example, by a method such as melt polycondensation, solution polycondensation, and interfacial polycondensation.

The amount of the aliphatic polycarboxylic acid linear acid anhydride to be used is based on 1 equivalent of the epoxy group in the copolymer component (A) and the number of aliphatic polycarboxylic acid linear anhydrides in the molecule. Is present in an amount of about 0.5 to about 2.
0 equivalents are preferred, and about 0.6 to about 1.2 equivalents are more preferred. When the amount of the aliphatic polycarboxylic acid linear acid anhydride used is within the above range, the resulting coating film has good appearance and excellent properties such as solvent resistance, impact resistance, and weather resistance.

[Curing Catalyst Component (C)] The curing catalyst component (C) used in the present invention, that is, the heat-latent cationic polymerization initiator (C), and the heat-latent cation polymerization initiator is used for a long time at room temperature. Is stable over a long period of time, but the cation reaction is initiated by applying heat, which is a sulfonium salt type compound, an anilium salt type compound, a pyridinium salt type compound, a toluidinium salt type compound, a phosphonium salt type compound, an iodonium salt. And the like. These are generally onium salts such as nitrogen, sulfur, phosphorus, iodine and the like containing antimony hexafluoride, phosphorus hexafluoride, boron tetrafluoride, and arsenic hexafluoride as anionic components.

As the heat-latent cationic polymerization initiator (C), specifically, for a sulfonium salt type compound, triphenylsulfonium boron tetrafluoride, triphenylsulfonium antimony hexafluoride, triphenylsulfonium arsenic hexafluoride , Arsenic tri (4-methoxyphenyl) sulfonium hexafluoride, arsenic diphenyl (4-phenylthiophenyl) sulfonium hexafluoride, antimony hexafluoride pt-butylbenzyltetrahydrothiophenium, etc .; N, N-dimethyl-N-benzylanilinium antimony hexafluoride,
N-dimethyl-N-benzylanilinium boron tetrafluoride, N, N-dimethyl-N- (4-chlorobenzyl) anilinium antimony hexafluoride, N, N-dimethyl-N
-(1-phenylethyl) anilinium antimony hexafluoride; N-benzyl-4 in the pyridinium salt type compound
-Dimethylaminopyridinium antimony hexafluoride, N
-Benzyl-4-diethylaminopyridinium trifluoromethanesulfonic acid, N- (4-methoxybenzyl)
-4-dimethylaminopyridinium antimony hexafluoride, N- (4-methoxybenzyl) -4-diethylaminopyridinium antimony hexafluoride and the like; in the case of toluidinium salt compounds, N, N-dimethyl-N- (4-methoxybenzyl) Antimony toluidinium hexafluoride,
N, N-diethyl-N- (4-methoxybenzyl) toluidinium antimony hexafluoride and the like; phosphonium salt type compounds such as ethyltriphenylphosphonium antimony hexafluoride and tetrabutylphosphonium antimony hexafluoride; and iodonium salt type compounds Arsenic diphenyliodonium hexafluoride, arsenic di-4-chlorophenyliodonium hexafluoride, arsenic di-4-bromophenyliodonium hexafluoride, arsenic di-p-tolyliodonium hexafluoride, phenyl (4-methoxyphenyl) iodonium Arsenic hexafluoride and the like can be mentioned.

Preferred specific examples include triphenylsulfonium boron tetrafluoride, triphenylsulfonium antimony hexafluoride, arsenic triphenylsulfonium hexafluoride, arsenic tri (4-methoxyphenyl) sulfonium hexafluoride, diphenyl (4- Phenylthiophenyl)
Sulfonium salt-type compounds such as sulphonium hexafluoride arsenic, pt-butylbenzyltetrahydrothiophenium antimony hexafluoride and the like, and particularly preferably p
Sulfonium salt-type onium salts using SbF6- as an anion component, such as -t-butylbenzyltetrahydrothiophenium antimony hexafluoride, may be mentioned.

Examples of commercially available heat latent cationic polymerization initiators include, for example, Sun Aid SI-60L, Sun Aid SI-80L, Sun Aid SI-100L, Sun Aid SI-80, Sun Aid SI-100, and Sun Aid SI.
-145, Sun-Aid SI-150, Sun-Aid SI-
160 (above, manufactured by Sanshin Chemical Industry Co., Ltd.).

Quaternary ammonium salts, imidazoles,
Known curing catalysts such as amines and melamines can easily react with epoxy groups in the copolymer component (A) and carboxyl groups in the curing agent component (B) even at room temperature. Depending on the embodiment of the product, these compounds may be used to improve the storage stability and coating properties (appearance such as smoothness) of the powder coating composition.
May be a problem.

The heat-latent cationic initiator component (C) used in the present invention is stable and inactive under storage conditions of about 40 ° C., so that the coating composition has good storage stability.

On the other hand, the component (C) used in the present invention shows almost no effect of accelerating hardening when the powder coating is stored, and the storage stability (chemical stability) of the powder coating is good.
In the baking temperature range of the powder coating at 0 ° C. or higher, the effect of promoting the curing is remarkably exhibited.

The role of the component (C) with respect to the components (A) and (B) in the components of the present invention is considered to have the following effects.

When the baking temperature of the coating film (generally 100 ° C. or higher) is reached, the cationic species generated by the thermal decomposition of the thermal latent cationic polymerization initiator component (C) becomes the active species, and the cationic component in the copolymer component (A) The ring-opening action of the epoxy group is promoted, and the ring-opened epoxy group not only promotes the ring-opening reaction to other epoxy groups, but also promotes the reaction with the carboxyl group in the curing agent component (B). Promotes a sequential reaction with an acid anhydride group in the curing agent component (B), so that the resulting coating film becomes densely crosslinked, and has physical properties (such as scratch resistance) and chemical properties (such as acid resistance). Properties) can be obtained.

The amount of the curing catalyst component (C) to be used is generally 1% in total of the copolymer component (A) and the curing agent component (B).
The amount is preferably about 0.01 to about 5 parts by weight, more preferably about 0.05 to about 3 parts by weight, based on the 00 weight section. When the amount of the curing catalyst component (C) used is 5 parts by weight or less, the curing reaction can be performed at an appropriate speed, and the smoothness of the coating film and the storage stability of the paint can be maintained.

[Additives] In the present invention, various additives usually added to paints can be used. For example, according to the purpose, the powder coating composition of the present invention may contain, as appropriate, an epoxy resin, a polyester resin, a synthetic resin composition including polyamide, a natural resin including cellulose or a cellulose derivative, or a semi-synthetic resin. The appearance of the coating film or the physical properties of the coating film can be improved by blending a resin composition.

For example, in the powder coating of the present invention, pigments, flow regulators, thixotropic agents (thixotropic regulators), charge regulators, surface regulators, gloss-imparting agents, anti-blocking agents may be appropriately added according to the purpose. Further, additives such as a plasticizer, an ultraviolet absorber, an anti-bake agent, and an antioxidant may be blended.

When an amine-based compound or an alkali compound is frequently used in the compounding composition, the cationic species generated from the curing catalyst component (C) may be captured at the time of baking heating, and curing may be inhibited. Is not preferred.

[Kneading of Powder Coating Composition] As a melt kneading apparatus for mechanically kneading a composition containing the components (A), (B) and (C), a heating roll machine,
Use a heating kneader, extruder (extruder) or the like.

Specific examples of the method for blending the thermosetting powder coating composition of the present invention include a roll machine, a kneader machine, a mixer (Banbury type, transfer type, etc.), a calendar facility, an extruder (extruder) and the like. Kneaders and kneaders are appropriately combined, and the conditions of each step (temperature, melting or non-melting, rotation speed, vacuum atmosphere, inert gas atmosphere, etc.) are appropriately set and mixed sufficiently uniformly. After that, a method of obtaining a powder coating composition in a uniform fine powder state by a pulverizer can be adopted, but the method is not limited thereto.

One embodiment of the compounding and kneading step of adding an additive or the like to the powder coating composition of the present invention is as follows. The thermosetting powder coating composition of the present invention may optionally contain an antiblocking agent, Agents, plasticizers, charge control agents, pigments, fillers,
Additives such as a bulking agent are added, and the mixture is sufficiently melt-kneaded in a range of about 40 to about 130 ° C., cooled, and then uniformly ground to an appropriate particle size (usually, about 100 mesh or less) to obtain a powder coating. .

[Coating Method and Baking Method] The powder coating obtained by pulverization is applied to an object to be coated, heated and thermally cured to form a coating film. Specific examples of the method of applying the thermosetting powder coating composition of the present invention include known coating methods such as an electrostatic coating method and a fluid immersion method.

When the thermosetting powder coating composition of the present invention is used as an overcoat,
In the case of using not only a conventional solvent-type paint but also a water-based paint, the paint film of the present invention has excellent properties in the film after baking, as in the case of using the solvent-type paint.

That is, an aqueous undercoat (including pigment and / or metal powder) is applied and dried for a predetermined time, and then the thermosetting powder coating composition of the present invention is coated with the undercoat by the method described above. And heat-cured by heating to form a coating film. The baking of the curable powder coating composition of the present invention is usually performed at a temperature in the range of 100 to 200 ° C. Preferably at a temperature of about 100 to about 160C, more preferably about 120 to about 140C, usually about 10 to about 160C.
By performing the reaction for about 60 minutes, the crosslinking reaction proceeds. After baking, it is cooled to room temperature, and a coating film having excellent properties can be obtained. The coating method to which the thermosetting powder coating composition of the present invention can be applied is also used for an automobile body or an automobile part.

[Concept of the word "derivative"] The concept of the word "derivative" used in the claims and the specification of the present application means 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. Group, or a residue in which these are linked by a hydroxyl group, a carboxyl group, an amino group, nitrogen, silicon sulfur, phosphorus, etc., and among these, particularly those having an aliphatic structure in a narrow sense. preferable.

Z is the same as above, for example, substituted by 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. It may be a group.

By appropriately selecting these substituents, various properties of the coating film formed by the powder coating composition of the present invention can be controlled.

[Concept of the term "storage stability"] The concept of the term "storage stability" used in the specification of the present application includes physical stability (blocking resistance) and chemical stability of a powder coating. Includes stability (solid phase resistance).

[0087]

Examples Examples, production examples and embodiments described below are as follows.
The purpose is to assist understanding of the contents of the present invention, and the description does not limit the present invention in any way. In the description, “parts” and “%” are values by weight unless otherwise specified.

[Production Example 1] Production of Copolymer Component (A) 66.7 parts of xylene was charged into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube.
The temperature was raised while stirring to the reflux temperature in a nitrogen atmosphere. After reaching the reflux temperature, the monomers shown in Table 1 and t-butyl-peroxy-2-ethylhexanoate as a polymerization initiator (trade name: Perbutyl O, manufactured by NOF Corporation)
Was added dropwise over 5 hours, and further maintained for 1 hour, and then 0.6 parts of perbutyl O was added dropwise at 100 ° C. and maintained for 2 hours. Xylene was removed from the polymerization solution obtained under reduced pressure to obtain a copolymer component (A-1). Further, as shown in Table 1, various copolymer components (A-1) were prepared by changing the type and composition of the monomer.
And (A-2) were obtained. Various physical properties of the copolymer were measured by the following methods.

(1) Glass transition temperature (Tg): It was calculated by the Fox equation based on the monomer composition. (2) Number average molecular weight (Mn): Measured by GPC using polystyrene as a standard.

[0090]

[Table 1] [Legend] ST: Styrene MMA: Methyl methacrylate nBMA: n-butyl methacrylate iBMA: iso-butyl methacrylate GMA: glycidyl methacrylate PB-O: t-butyl peroxy-2-ethylhexanoate.

[Production Example 2] Production of linear linear anhydride of aliphatic dicarboxylic acid 1 mol of dodecane diacid and 0.9 mol of acetic anhydride were charged into a reaction vessel, and the temperature was raised to 130 ° C.
The reaction was carried out for 5 hours while removing generated acetic acid by a vacuum line so that acetic anhydride did not flow out of the system. Thereafter, the mixture was immediately cooled, and a white solid was recovered.
A linear linear anhydride of the acid was obtained. The melting point of this compound is 81-
91 ° C. Also, a linear linear anhydride of sebacic acid was produced in the same manner using sebacic acid to obtain a product having a melting point of 74 to 81 ° C.

[Evaluation of Performance] The powder coatings obtained in Examples and Comparative Examples described later were evaluated by the following methods.

(1) Smoothness The appearance of the coating film was observed.
も の indicates a slightly uneven surface, and × indicates a poor smoothness.

(2) Visibility Using a DOI meter (manufactured by Paul N. Gardner), the GM9
The coating film was evaluated according to 1013. DOI value is 9
A film having a sharpness of 0 or more and 100 or less was evaluated as ◎, a film having a sharpness of 70 or more and less than 90 was evaluated as 、, and a film less than 70 was evaluated as a film having poor sharpness.

(3) Gloss The gloss was measured (60 ° gloss).

(4) Impact resistance test (Dubon-type impact resistance test) The test was carried out in accordance with JIS K 5400 6.13.3. The weight used here is 500 g. The numerical value of the evaluation result was indicated by the drop height at which cracks and peeling occurred in the coating film.

(5) Solvent resistance The coating film surface was reciprocated by a gauze impregnated with xylol.
Observation was performed after the rubbing. ◎ indicates no trace, ○ indicates a slight trace, and × indicates a trace.

(6) Scratch resistance The surface of the coating film was subjected to a scratch test using a 0.3% cleanser suspension with a brush, and the gloss value (20 ° gloss) was evaluated before and after the friction. Then, the gloss retention was calculated. Those having a gloss retention of 60% or more were evaluated as ◎ as a scratch-resistant coating film, 50 to 60% were evaluated as ○, and those less than this were evaluated as x as a non-scratch coating film.

(7) Weathering test A 2000 hour acceleration test was performed using a QUV tester, and the gloss (60 °) of the coating film before and after the acceleration test was measured.
The gloss retention (%) was determined. The gloss remaining ratio is expressed by the following formula [Equation 1].
Was calculated by

[0100]

## EQU1 ## Gloss persistence (%) = (60 ° gloss after accelerated test) ÷ (60 ° gloss before accelerated test) × 100 Those having a gloss retention of 80% or more: 、, 70-80% Was evaluated as ○, and less than that was evaluated as ×.

(8) Storage stability test of powder coating material (blocking resistance test) 6 g of powder coating material was placed in a cylindrical container having an inner diameter of 25 mm, and after storing at 40 ° C for 14 days, the powder coating material was placed in a cylindrical container. , And the blocking state was observed visually and by finger touch. As a result, ◎ indicates no abnormality, ○ indicates slightly inferior, and × indicates inferior.

(9) Storage stability test of powder coating (solid-phase reactive wiping test) After storing the powder coating under the above conditions, 10 mmφ, 0.3 g
Was prepared and adhered on a plate, then kept vertically, and the dripping state of the pellet when baked at 140 ° C. for 30 minutes was measured. Those that ride 150 mm or more are evaluated as ◎ as powder coatings having excellent solid phase resistance, and 100 to 150 mm are rated as ○, and those below are rated as ×.
And

<Examples 1 to 5, Comparative Examples 1 to 5> [Preparation of powder coating material] The copolymer component (A), the curing agent component (B) and the curing catalyst component (C) are shown in Table-2. Blended in proportions, based on a total of 100 parts of components (A) and (B)
Trade name REGIMICS RL-4 (manufactured by Mitsui Chemicals, low viscosity acrylic resin, flow regulator), trade name Tinuvin 14
4 (manufactured by Ciba-Geigy, light stabilizer), 1 part each of benzoin (an anti-armpit agent), and 2 parts of Tinuvin 900 (manufactured by Ciba-Geigy, an ultraviolet absorber), and after thoroughly mixing them, The mixture was melt-kneaded under the conditions of 90 ° C. using a co-kneader “TCS-30” manufactured by Buss Corporation, cooled, pulverized with a pulverizer, and separated through a 150-mesh sieve. The powder was recovered and a powder coating was prepared.

[Preparation of Base-Treated Steel Sheet] A zinc-phosphate-treated 0.8 mm-thick satin-finished steel sheet is coated with a polyester-melamine cross-linked black paint to a thickness of 20 μm.
Baking was performed at 70 ° C. for 30 minutes to prepare a base-treated steel sheet.

[Preparation, coating and baking of test plate] The powder coating obtained by the method of the present invention and the powder coating obtained by the comparative example were
Electrostatic coating was performed on the base-treated steel sheet so that the film thickness became 60 to 70 μm, and baking was performed at 150 ° C. for 30 minutes to obtain a test plate.

The results of evaluation of the powder coatings and coating films formed in Examples 1 to 5 are shown in Tables 3 and 4. Tables 3 and 4 show the results of evaluation of the powder coatings and coating films formed in Comparative Examples 1 to 5 related to this.

The powder coatings of Examples 1 to 5 shown in Table 2 are within the scope of the present invention, and experiments in which the types of the curing agent component (B) and the curing catalyst component (C) were changed. These results show excellent appearance, physical properties and weather resistance of the coating film, and excellent storage stability of the coating composition.

Comparative Example 1 is an example in which an aliphatic divalent carboxylic acid was used as a curing agent. In this case, the solvent resistance and scratch resistance of the coating film were poor. Comparative Example 2 is an example in which an aromatic cyclic acid anhydride was used as a curing agent, and in this case, various performances were inferior. Comparative Example 3 is an example in which the curing catalyst was not used. In this case, the baking of the coating film was insufficient and the physical properties of the coating film were inferior.

Comparative Example 4 is an example in which a salt of an amine compound not claimed in the present invention was used as a curing agent catalyst. In this case, the storage stability (solid phase reactivity) of the paint was inferior. Comparative Example 5 is an example in which the curing agent component (B) was not used, and in this case, the scratch resistance and weather resistance of the coating film were inferior.

[0110]

[Table 2] Legend: DDA anhydride: Dehydration condensate of dodecane diacid Sebacic anhydride: Dehydration condensate of sebacic acid Terephthalic anhydride: Dehydration condensate of terephthalic acid Additol VXL1381: Aliphatic polyanhydride manufactured by Fianovaresin Product DDA: Dodecane diacid L1: Sun-Aid SI-60L (Aromatic sulfonium salt-based heat latent cationic polymerization initiator manufactured by Sanshin Chemical Industry Co., Ltd.) L2: Benzyl-4-hydroxyphenylsulfonium hexafluorophosphorus DBU-Fa : DBU formate (an amine salt formed from 1,8-diaza-bicyclo acid [5,4,0] undecene-7 and formic acid).

[0111]

[Table 3]

[0112]

[Table 4]

[0113]

The thermosetting powder coating composition according to the present invention exhibits at least the following effects at the same time. Excellent storage stability before film formation (during storage). Excellent low-temperature fusibility / low-temperature curability during coating film formation. Excellent coating film properties and physical properties after coating film formation.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroyuki Sakayama 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside (72) Inventor Tsuyoshi Matsumoto 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Chemical Co., Ltd.

Claims (8)

[Claims] A thermosetting powder coating composition comprising a copolymer component (A), a curing agent component (B), and a curing catalyst component (C), wherein the copolymer component (A) )
(A1) at least one kind of radically polymerizable monomer having at least one radically polymerizable functional group and at least one epoxy group in one molecule, and (a2) 1
A copolymer obtained by radical polymerization in a reaction system containing at least one monomer having no at least one radical polymerizable functional group in the molecule and not having an epoxy group,
The curing agent component (B) is an aliphatic polycarboxylic carboxylic acid linear anhydride, and the curing catalyst component (C) is a thermolatent cationic polymerization initiator. Body paint composition. 2. The curing catalyst component (C) is used in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the total of the components (A) and (B).
The thermosetting powder coating composition according to claim 1, which is contained by weight. 3. The thermosetting powder coating composition according to claim 1, wherein the component (C) is an aromatic sulfonium salt. 4. The equivalent ratio of the functional group present in the molecule of component (A) to the functional group present in the molecule of component (B) is 1 equivalent of epoxy group present in the molecule of component (A). The total of the carboxyl group and the acid anhydride (anhydride) group present in the molecule of the component (B) is 0.5 to 2.0 equivalents. 3. The thermosetting powder coating composition according to item 1. 5. An aliphatic polycarboxylic acid linear acid anhydride,
(B-1) adipic acid, (b-2) sebacic acid,
(B-3) A compound derived from at least one compound selected from the group consisting of eicosane diacid and (b-4) dodecane diacid by dehydration condensation. Item 4. The thermosetting powder coating composition according to item 1. 6. The thermosetting powder coating composition according to claim 1, wherein a melting point of the aliphatic polycarboxylic acid linear anhydride is 40 to 150 ° C. 7. A method for producing a thermosetting powder coating using the composition according to claim 1, wherein the raw material contains at least the component (A), the component (B) and the component (C). And a step of cooling and pulverizing the melt-kneaded product. 8. The method according to claim 7, wherein the melt-kneading step is performed at a temperature of 40 to 130 ° C.