JP2000160061A - Thermosetting powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder coating material excellent in smoothness and processability. SOLUTION: This coating material contains as a thermosetting resin component (A) 90-99 pts.wt. hydroxy-containing base resin except the following hydroxy-containing rubber composite resin particles, (B) l-10 pts.wt. hydroxy- containing rubber-composite resin particles each of which is composed of a core of a rubbery polymer and a shell of a vinyl polymer, and (C) 10-60 pts.wt. blocked polyisocyanate compound.

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 which provides a coating film having excellent finished appearance and processability.

[0002]

2. Description of the Related Art Conventionally, thermosetting powder coatings have been widely used as outdoor or indoor applications in the field of industrial products such as home appliances, automobiles, vehicles, office supplies, steel furniture, and building materials. I have. As the above-mentioned thermosetting powder coating, there is known a powder coating obtained by blending a blocked polyisocyanate crosslinking agent with a hydroxyl group-containing acrylic resin or a hydroxyl group-containing polyester resin. The powder coating forms a coating film having excellent workability as compared with a thermosetting powder coating obtained by blending a polyacid curing agent with a glycidyl group-containing acrylic resin, but a coated article requiring more workability. Is inadequate, and at present the user is demanding improvement in workability.

As a method for improving the processability of a powder coating, it is conceivable to mix rubber particles having excellent processability into a conventional block polyisocyanate-curable powder coating material. When blended in a small amount, the workability is improved and the smoothness becomes inferior. On the other hand, when blended to such an extent that the smoothness does not deteriorate, the workability is not improved, and it is difficult to satisfy both the performance of the coating film appearance and the workability. Met.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the conventional problems, and as a result, have found that a combination of a blocked polyisocyanate-curable powder coating material and a specific rubber composite resin particle is required. As a result, a powder coating having excellent finishability and processability has been developed.

That is, the present invention relates to: 1. The following components (A) 90 to 99 parts by weight of a hydroxyl group-containing base resin other than the following hydroxyl group-containing rubber composite resin particles: (B) a rubber polymer as a core layer, The present invention relates to a thermosetting powder coating material comprising, as a thermosetting resin component, 1 to 10 parts by weight of a hydroxyl group-containing rubber composite resin particle serving as a shell layer (C) 10 to 60 parts by weight of a blocked polyisocyanate compound.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the hydroxyl group-containing base resin used in the powder coating of the present invention, those conventionally used in blocked polyisocyanate-curable powder coatings can be used. Examples of the hydroxyl-containing base resin include a hydroxyl-containing polyester resin, a hydroxyl-containing acrylic resin, a hydroxyl-containing fluororesin, and a hydroxyl-containing silicone resin. These hydroxyl group-containing resins have a weight average molecular weight of about 500.
Those having a range of from 100 to 100,000, particularly 1000 to 80,000 are preferred. The softening temperature of the resin is about 20 to 10
Those having a temperature range of 0 ° C, particularly 25 to 80 ° C, are preferred. Hydroxyl content is about 20 to 300 KOHmg in resin hydroxyl value.
/ G, especially in the range of about 25-200 KOH mg / g.

As the hydroxyl group-containing polyester resin,
For example, aromatic or alicyclic dicarboxylic acids such as (phthalic anhydride), isophthalic acid, terephthalic acid, dimethyl isophthalate, dimethyl terephthalate, hexahydro (anhydride) phthalic acid and tetrahydro (anhydride) phthalic acid, and (poly) ethylene glycol , (Poly) propylene glycol, butylene glycol, butylene glycol, neopentyl glycol, 1,6-hexanediol, dihydric alcohols such as dimethylpropionic acid, monocarboxylic acids such as benzoic acid if necessary, (anhydrous) trimellit Examples of the resin include a resin obtained by reacting with a trivalent or higher carboxylic acid such as an acid, and a trivalent or higher alcohol such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol.

[0008] Among the polyester-based resins, it is particularly preferable to apply to a polyester resin containing, as an acid component, isophthalic acid which is inferior in workability as a main component.

The hydroxyl group-containing acrylic resin includes, for example, a hydroxyl group-containing radically polymerizable unsaturated monomer (eg, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate), and a glass transition temperature of 40.
C. or higher hard acrylic monomer (for example, methyl methacrylate, ethyl methacrylate, iso-butyl methacrylate, ter-butyl methacrylate, ter-butyl acrylate, etc.) and, if necessary, a soft acrylic monomer (for example, methyl Acrylate, ethyl acrylate, n-butyl methacrylate, iso-butyl acrylate, 2-ethylhexyl (meth) acrylate, stearyl methacrylate, etc.), radical polymerizable unsaturated monomers other than acrylic monomers (for example, styrene, vinyltoluene, α-methylstyrene, ( (Meth) acrylonitrile, (meth) acrylamide, etc.), radical-polymerizable unsaturated monomers containing a functional group other than the above-mentioned hydroxyl group (eg, glycidyl (meth) acrylate, methyl glycidyl) Meth) acrylate, and the like)
And a hydroxyl group-containing acrylic base resin obtained by subjecting the resin to a radical copolymerization reaction.

Examples of the hydroxyl group-containing fluororesin include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, and fluoroolefins (for example, ethylene tetrafluoride, ethylene trifluoride, ethylene difluoride, ethylene trifluoride and ethylene difluoride). And copolymers with other radically polymerizable monomers (vinyl ethers, allyl ethers, vinyl esters, propenyl esters, olefin compounds, etc.) if necessary.

Further, as the fluorine-based resin, in the above-mentioned hydroxyl-containing acrylic resin, perfluoroalkyl (meth) acrylate (for example, perfluorobutylethyl (meth) acrylate, perfluoroisononylethyl (meth) ) Acryle
And perfluorooctylethyl (meth) acrylate) as an essential monomer component.

As the hydroxyl-containing silicone resin, in the above-mentioned hydroxyl-containing acrylic resin, vinyltrimethoxysilane, (meth) acryloxypropyltrimethoxysilane, (meth) acryloxypropyltrimethylsilane and the like are essential as other monomer components. The resin used as the monomer component is exemplified.

In the above-mentioned hydroxyl group-containing resin,
A hydroxyl group-containing polyester resin is preferred from the viewpoint of processability, smoothness, cost, and the like.

The blocked polyisocyanate compound used in the powder coating of the present invention has a softening point of about 20 to 100 ° C., preferably about 25 to 80 ° C., in which the isocyanate group of the polyisocyanate compound is blocked by a blocking agent. is there. Examples of the polyisocyanate compound include aliphatic diisocyanate compounds such as hexamethylene diisocyanate, trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, pentamethylene diisocyanate, lysine diisocyanate, and 1,3-butylene diisocyanate. Examples of the diisocyanate compound include isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4- (or -2,6-) diisocyanate, 1,3- (or 1,4
-) Di (isocyanatomethyl) cyclohexane, 1,4
-Cyclohexane diisocyanate, 1,3-cyclopentane diisocyanate, 1,2-cyclohexane diisocyanate, etc .: As aromatic diisocyanate compounds, xylylene diisocyanate, meta-xylylene diisocyanate, tetramethyl xylylene diisocyanate, tolylene diisocyanate, 4,4 ' -Diphenylmethane diisocyanate, (m- or p-) phenylene diisocyanate, etc .: Other polyisocyanates include polyphenylene having three or more isocyanate groups such as triphenylmethane-4,4 ', 4 "-triisocyanate. Isocyanate compounds, ethylene glycol, propylene glycol, 1,4-butylene glycol, polyalkylene glycol, trimethylolpropane, hexanetriol The amount of isocyanate groups relative to the polyol having a hydroxyl becomes excessive amount of a polyisocyanate compound obtained by reacting adducts, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,
4'-diphenylmethane diisocyanate, 4,4'-
Burette type adducts such as methylenebis (cyclohexyl isocyanate), isocyanuric ring type adducts, and the like.

As the blocking agent used for blocking the above-mentioned polyisocyanate compound, for example, any of conventionally known blocking agents of phenol type, lactam type and oxime type can be used. Specific examples of these blocking agents include phenol-based blocking agents such as phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, hydroxydiphenyl, t-butylphenol, and methyl benzoate. , Ε
-Caprolactam, δ-valerolactam, γ-butyrolactam, β-propiolactam and the like: Examples of the oxime-based blocking agent include acetoaldoxime, acetoxime, methylethylketoxime, diacetylmonooxime, benzophenone oxime, and cyclohexane oxime.

The mixing ratio of the blocked polyisocyanate compound is such that the number of isocyanate groups is about 0.3 to 1.5, preferably about 0.5 to 1.2 per hydroxyl group of the base resin.
It is blended so as to be in the range of the individual. The base resin 10
It is usually in the range of about 10 to 120 parts by weight, preferably about 20 to 100 parts by weight, based on 0 parts by weight.

The core-shell type hydroxyl-containing rubber composite resin particles used in the powder coating of the present invention are particles having a core-shell structure in which a rubber-like polymer is used as a core layer and a vinyl-based polymer is used as a shell layer. About 0.1-30KO
Hmg / g, especially in the range of about 0.5-20 KOH mg / g, is preferred. Hydroxyl value is about 0.1KOHmg / g
If it is less than 30 KOH mg / g, the water resistance, weather resistance, smoothness, etc. are undesirably reduced. The hydroxyl groups have been introduced into the shell layer.

The core-shell structure may have a three-layer structure of a core layer, a mid layer, and a shell layer. In this case, the core layer or the mid layer is formed of a rubber-like polymer, and the shell layer is formed of vinyl. Those formed of a system polymer can be used. The particle size of the particles is about 0.05 μm to 150 μm,
Preferably, it is in the range of about 0.1 μm to 100 μm. When the particle diameter is less than about 0.05 μm, the workability of the electrostatic coating of the powder coating decreases, while when it exceeds about 150 μm, the smoothness of the coating film is deteriorated, which is not preferable. When the softening temperature (glass transition temperature) of the shell layer is less than about 20 ° C., the particles fuse together during storage of the powder coating to form small agglomerates, which are transferred to the transport tube of the electrostatic coating machine. It is not preferable because it causes clogging and causes a coating trouble or a coating film to be uneven.

The rubbery polymer forming the core layer is a polymer of an unsaturated monomer forming a rubbery polymer. Specific examples of the unsaturated monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate Alkyl (meth) acrylates such as: vinyl esters such as vinyl acetate: vinyl halides such as vinyl chloride, vinyl fluoride, vinylidene chloride, and vinylidene fluoride or vinylidene halides:
Nitrogen-containing unsaturated monomers such as (meth) acrylonitrile and (meth) acrylamide: aromatic compounds such as styrene, α-methylstyrene, and vinyl toluene: containing hydroxyl groups such as hydroxyethyl (meth) acrylate and methylol (meth) acrylamide Unsaturated monomer: unsaturated acid such as (meth) acrylic acid; and gen-based monomers such as butadiene and isoprene. These are one or two
More than one species can be used in combination. Representative examples of the polymer include, for example, poly (meth) acrylate rubber, polybutadiene rubber, polyisoprene rubber, polyvinyl chloride, styrene-butadiene rubber, styrene-butadiene-styrene rubber, styrene-isoprene-styrene rubber, Styrene-butylene rubber, styrene-ethylene rubber, ethylene-propylene rubber and the like can be mentioned. Among them, poly (meth) acrylate rubber, polybutadiene rubber, polyisoprene rubber and styrene-butadiene rubber are particularly preferred.

The vinyl polymer forming the shell layer is formed of the above-mentioned vinyl monomer, for example, a hydroxyl group-containing unsaturated monomer (for example, 2-hydroxyethyl (meth) acrylate,
C2-C8 hydroxyalkyl esters of acrylic acid or methacrylic acid such as 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate; polyethylene glycol, polypropylene glycol, polybutylene glycol and the like Monoester of polyether polyol with unsaturated carboxylic acid such as (meth) acrylic acid; polyether polyol such as polyethylene glycol, polypropylene glycol, polybutylene glycol and hydroxyl group-containing unsaturated monomer such as 2-hydroxyethyl (meth) acrylate Monoether with;
Adducts of α, β-unsaturated carboxylic acids with monoepoxy compounds such as Kadura E10 (manufactured by Shell Chemical) and α-olefin epoxides; glycidyl (meth) acrylate and acetic acid, propionic acid, pt-butyl Adducts with monobasic acids such as benzoic acid and fatty acids; unsaturated compounds containing an acid anhydride group such as maleic anhydride and itaconic anhydride; and glycols such as ethylene glycol, 1,6-hexanediol and neopentyl glycol Mono- or di-esterified products of the compounds; hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether; hydroxyl-containing monomers containing chlorine such as 3-chloro-2-hydroxypropyl (meth) acrylate; allyl alcohol, etc.) With alkyl (meth) Rate (the above-mentioned hard acrylic monomer or soft acrylic monomer, etc.), unsaturated monomers such as the above-mentioned nitrogen-containing unsaturated monomers, aromatic compounds, epoxy group-containing unsaturated monomers, and the like. As described above, preferably, a vinyl polymer adjusted to a range of about 30 to 110 ° C. can be used.

The above-mentioned method for producing the rubber composite particles includes a conventionally known method, for example, an emulsion polymerization method in which a vinyl-based unsaturated monomer and a radical polymerizable initiator are added in the presence of a rubber-like polymer emulsion in advance. It can be obtained by a suspension polymerization method or the like.

The hydroxyl group-containing rubber composite resin particles include, for example, Staphyloid AC-4030 as a trade name of Takeda Pharmaceutical Co., Ltd.

The mixing ratio of the above-mentioned hydroxyl-containing rubber composite resin particles is 1 to 10 parts by weight with respect to 90 to 99 parts by weight of the hydroxyl-containing base resin, and 95 to 98 parts by weight of the hydroxyl-containing base resin.
It is preferably in the range of 2 to 5 parts by weight based on parts by weight.
If the compounding ratio of the hydroxyl group-containing rubber composite resin particles is less than 1 part by weight, the processability decreases, and if it exceeds 10 parts by weight, the coating film smoothness, water resistance and the like decrease.

The powder coating material of the present invention may contain, if necessary, a powder such as a blocking agent dissociation catalyst, a filler, a color pigment, a fluidity modifier, other polymer fine particles, a surface modifier, a curing accelerator, and a slipperiness imparting agent. An additive for body paint or the like can be blended.

The powder coating of the present invention is applied by, for example, an electrostatic powder spray, a triboelectric coating machine or the like.
The coating can be applied in a range of about 30 to 200 μm, preferably about 40 to 100 μm. The conditions for baking the coating film are usually about 160 to 210 ° C. for about 30 to 60 minutes.

The powder coating of the present invention can be applied to conventionally used substrates. As the base material, for example, metal materials such as steel, zinc, aluminum, copper, and tin;
Examples include those obtained by subjecting these metals to a surface treatment, and a base coat film obtained by subjecting these metal materials to primer or intermediate coating as necessary.

The field of application can be applied to, for example, vehicles, home appliances, buildings, roads, office equipment, and the like.

[0028]

The present invention will be described more specifically below with reference to examples. In the examples and comparative examples, “parts” are based on weight.

Example 1 GV-560 (manufactured by Nippon Yupika Co., Ltd., isophthalic acid / trimethylolpropane / neopentyl glycol)
95 parts of 0.973 / 0.104 / 0.808 molar ratio, softening temperature of 57 ° C., hydroxyl value of 52 KOH mg / g, staphyloid AC-4030 (Takeda Pharmaceutical Co., Ltd., trade name, hydroxyl value of about 5 KOH mg / g1) Next particle size about 0.5μ
m) 5 parts, Vestagon B1530 (manufactured by Huls, NC
10 parts of O content (about 15%) and 15 parts of JR603 (manufactured by Teica Co., Ltd., titanium oxide) were mixed, melt-kneaded by an extruder, cooled, pulverized finely by an atomizer, and filtered by 150 mesh to obtain a mixture of Example 1. A polyester resin powder coating was manufactured.

Example 2 In Example 1, GV-560 was added at 95 as a resin component.
Part and 5 parts of staphyloid AC-4030 by GV-5
60 parts to 90 parts and staphyloid AC-4030 to 10 parts
A polyester resin powder coating material of Example 2 was produced in the same manner as in Example 1 except that parts were replaced.

Example 3 Hydroxyl-containing acrylic resin (2-hydroxyethyl methacrylate / styrene / methyl methacrylate / n-butyl methacrylate = 30/10/50/10 "weight ratio")
95 parts by weight, average molecular weight 8000, softening point 26 ° C.), Staphyloid AC-4030 (Takeda Pharmaceutical Co., Ltd., trade name, hydroxyl value about 5 KOHmg / g, primary particle diameter about 0.5 μm)
m) 5 parts, Vestagon B1530 (manufactured by Huls, NC
10 parts of O content (about 15%) and 15 parts of JR603 (titanium oxide, manufactured by Teica Co., Ltd.) were mixed, melt-kneaded by an extruder, cooled, finely pulverized by an atomizer, and filtered by 150 mesh to obtain a mixture of Example 3. Acrylic resin powder coating was manufactured.

Comparative Example 1 In Example 1, the same GV-
A polyester resin powder coating material of Comparative Example 1 was produced in the same manner as in Example 1 except that 560 was changed to 100 parts and staphyloid AC-4030 was changed to 0 parts.

Comparative Example 2 In Example 1, the same GV-
85 parts of 560 and 1 part of staphyloid AC-4030
Comparative Example 2 in the same manner as in Example 1 except that 5 parts were replaced.
A polyester resin powder coating was manufactured.

The powder coatings of the above Examples and Comparative Examples were subjected to electrostatic powder coating on a galvanized steel sheet subjected to a chemical conversion treatment with zinc phosphate (0.7 × 70 × 150 mm).
The coating was formed by heating at 0 ° C. for 30 minutes.

Table 1 shows the test results of Examples and Comparative Examples.

[0036]

[Table 1]

Finish appearance: The smoothness of the coating film surface was visually observed. ；: Good, Δ: poor, ×: extremely poor.

Film gloss: JIS K-5400 7.6
(1990). (Reflectance: 60 degrees) Erichsen test: JIS K-5400 8.2 (19
90). The extrusion distance (mm) until cracking and peeling of the coating film was measured.

Impact test: JIS K-5400
According to 3.2 (1990) Dupont impact resistance test,
An impact was applied to the coated surface of the coated plate under the conditions of a drop weight of 500 g, a tip diameter of a hammer of 1/2 inch, and a drop weight height of 50 cm. Then, a cellophane adhesive tape was adhered to the area where the impact was applied, and the degree of peeling of the coating film when the tape was instantaneously peeled was evaluated. ：: no peeling was observed on the painted surface, Δ: slight peeling was observed on the painted surface, ×: considerable peeling was observed on the painted surface

[0040]

According to the present invention, in particular, by incorporating the hydroxyl-containing rubber composite resin particles into the isocyanate-curable powder coating, the hydroxyl-containing rubber composite resin particles are present as particles in the coating film, and the impact from outside The workability is improved by absorbing the energy due to the above. Further, since the rubber composite resin particle component is chemically bonded to the hydroxyl group-containing base resin by the isocyanate crosslinking agent, the processability is further improved, and the durability such as weather resistance and water resistance is also improved.

In the case of rubber composite resin particles containing no hydroxyl group, the workability is improved but the smoothness is deteriorated by increasing the blending amount. On the other hand, if the blending amount is reduced to such an extent that the smoothness is not deteriorated, the processability is not sufficient. Although there is a problem, the hydroxyl-containing rubber composite resin particles used in the present invention are chemically bonded to the hydroxyl-containing base resin by the isocyanate cross-linking agent as described above. Thus, both the smoothness and the workability were satisfied.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J038 CA021 CA022 CC021 CC022 CC071 CC072 CC081 CC082 CD091 CD092 CE051 CE052 CG141 CG142 CG161 CG162 CG171 CG172 CH031 CH032 CH041 CH042 CH121 CH122 CH171 CH172 CJ131 DD132 DB221 DB221 DB221 DL002 KA21 NA01 PA02 PB05 PB06 PB07 PC02

Claims (2)

[Claims] The following components (A) 90 to 99 parts by weight of a hydroxyl-containing base resin other than the following hydroxyl-containing rubber composite resin particles (B) A hydroxyl-containing base resin having a rubber-like polymer as a core layer and a vinyl polymer as a shell layer. A thermosetting powder coating material comprising 1 to 10 parts by weight of rubber-containing composite resin particles (C) 10 to 60 parts by weight of a blocked polyisocyanate compound as a thermosetting resin component. 2. The hydroxyl group-containing base resin according to claim 1, wherein the hydroxyl group-containing base resin is at least one hydroxyl group-containing base resin selected from a hydroxyl group-containing polyester resin, a hydroxyl group-containing acrylic resin, a hydroxyl group-containing fluororesin, and a hydroxyl group-containing silicon resin. Thermosetting powder coating.