JP2003286436A - Thermosetting epoxy resin powder coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosetting epoxy resin powder coating. <P>SOLUTION: The thermosetting epoxy resin powder coating comprises 100 pts.wt. of an epoxy resin powder comprising at least one curing agent selected among an amine-based curing agent, acid-based curing agent, acid anhydride- based curing agent, polyamide-based curing agent, phenolic hydroxyl group- containing curing agent, dicyanodiamide-based curing agent, cationic polymerization reaction type curing agent and hydrazine-based curing agent and an epoxy resin having a melting point of 90-140°C, an average molecular weight of 1,000-4,000 and an epoxy equivalent of 800-4,000, and 1-10 pts.wt. of an epoxy resin bearing a naphthalene skeleton. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermosetting epoxy resin powder coating material having excellent corrosion resistance.

[0002]

2. Description of the Related Art Conventionally, epoxy powder coating materials are generally used for coated parts such as machine parts and water pipes which do not require weather resistance because they have good adhesion, corrosion resistance and mechanical properties. ing.

However, recently, powder coatings have become more recognized as environmentally friendly coatings, and their general use has been further advanced, and while the coating range has been expanded, even better corrosion resistance and low temperature curing properties have been achieved. Is desired.

[0004]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of providing a thermosetting epoxy powder coating material having excellent corrosion resistance.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that 5 to 10 parts by weight of an epoxy resin having a naphthalene skeleton is added to a thermosetting epoxy resin powder. It was found that the thermosetting type epoxy powder resin coating film having a better anticorrosion property than ever can be obtained by containing a part thereof, and the present invention has been completed.

That is, the present invention has a melting point of 90 to 140 ° C., an average molecular weight of 1000 to 4000, and an epoxy equivalent of 800 to 4.
The present invention relates to a thermosetting epoxy powder coating material characterized by containing 1 to 10 parts by weight of an epoxy resin having a naphthalene skeleton in 100 parts by weight of an epoxy resin powder containing 000 epoxy resins and a curing agent.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below.

The epoxy resin powder used in the present invention is
Melting point 90 to 140 ° C., average molecular weight 1000 to 4000,
It contains an epoxy resin having an epoxy equivalent of 800 to 4000 and a curing agent. Epoxy resin has a melting point of 90-
140 ° C., preferably 95-135 ° C., average molecular weight 10
00-4000, preferably 1200-3000, epoxy equivalent 800-4000, preferably 850-300
It is 0.

If the melting point is less than 90 ° C., stringing will occur during powder electrostatic coating due to preheating, resulting in poor smoothness of the coating film, and the molten powder coating material tends to accumulate at the tip of the powder coating gun. When this is applied, the smoothness of the coating film may deteriorate. On the other hand, when the temperature exceeds 140 ° C., the coating material is cured before it melts and flows, and the smoothness of the coating film deteriorates. If the average molecular weight is less than 1000, it is difficult to maintain the solid state at room temperature and blocking is likely to occur.
If it exceeds 000, the coating composition is cured before it melts and flows, so that the smoothness of the coating film deteriorates. When the epoxy equivalent is less than 800, unreacted epoxy groups increase, which is not good in terms of water quality.

As the epoxy resin, conventionally known epoxy resins such as bisphenol-epichlorohydrin type epoxy resin, alicyclic epoxy resin, novolac type epoxy resin and acrylic epoxy resin can be used. From the viewpoints of processability, anticorrosion property, water pollution resistance, etc., it is particularly preferable to use a bisphenol-epichlorohydrin type epoxy resin. Specific examples of the bisphenol-epichlorohydrin type epoxy resin include trade names such as Epicote 1004,
Same as left 1007 (above, Yuka Shell Epoxy Co., Ltd.), Araldite 6084, same left 6097, same left 60
99 (above, manufactured by Ciba-Geigy), DER-664,
Same as left 667 (made by Dow Chemical Co.) and other bisphenols
An epichlorohydrin type epoxy resin can be mentioned.

As the curing agent used in the powder coating composition of the present invention, amine curing agents, acid curing agents, acid anhydride curing agents,
It is possible to use at least one epoxy resin curing agent selected from imidazole curing agents, polyamide curing agents, phenolic hydroxyl group-containing curing agents, dicyandiamide curing agents, cationic polymerization reaction curing agents, and hydrazine curing agents. it can. Specific examples of the above-mentioned curing agent include carboxyl group-containing polyester resins, carboxylic acids such as adipic acid and phthalic acid, acid anhydrides such as ethylene glycol bis (anhydrotrimellitate), and 2-phenylimidazoline. Examples thereof include an imidazole compound, a polyamide compound, a phenolic hydroxyl group-containing compound such as a phenol resin, a dicyandiamide compound or a modified product thereof, and a hydrazine compound such as adipic acid dihydrazide.

The above curing agent is 2 to 20 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the epoxy resin,
Particularly preferably, it is blended in an amount of 4 to 10 parts by weight. If the blending amount is less than 2 parts by weight, curing will be poor,
Not preferable. On the other hand, if the blending amount is more than 20 parts by weight, the reaction occurs due to the heat during the production of the paint, which not only impairs the coating film forming ability but also significantly reduces the storage stability of the paint, which is not preferable. .

Further, a curing agent for a carboxyl group-containing polyester resin can form a hybrid powder coating based on an epoxy resin, has a good balance of reactivity, adhesion, anticorrosiveness, and physical performance, and has various properties. An article to be coated can be formed.

Examples of such polyester resins include resins produced from unsaturated dicarboxylic acids and polyols in excess of unsaturated dicarboxylic acids. Here, as the unsaturated dicarboxylic acid used, for example,
Succinic acid, adipic acid, sebacic acid, azelaic acid,
Examples thereof include dicarboxylic acids such as terephthalic acid, isophthalic acid, hexahydroterephthalic acid and hexahydroisophthalic acid, their acid esters, and acid anhydrides. on the other hand,
Examples of the polyol include ethylene glycol and
1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5-pentaglycol, neopentyl glycol, 1,8-octane glycol, 1,9-nonane glycol, diethylene glycol, cyclohexane- 1,4-diol, cyclohexane-1,4-dimethanol, diol dimer acid, trimethylene propanol, glycerin, hexanetriol, and further N, N, N ′, N′-tetrakis (2-
Hydroxypropyl) ethylenediamine and glycols such as bisphenol A ethylene oxide or propylene oxide adducts. When a polyol containing an amide bond in the molecule is used, examples of amines used for producing such a polyol include hexamethylenediamine, xylenediamine, isophoronediamine, monoethanolamine, and isopropanoltriamine. Examples of the diamine, triamine, amino alcohol and the like can be used, and these can be used alone or in combination of two or more kinds.

The acid value of the carboxyl group-containing polyester resin is usually 20 to 90 mg KOH / g, preferably 20 to 8
0 mgKOH / g, particularly preferably 25 to 60 mgKOH / g is suitable. In the present invention, the amount of the epoxy resin and the carboxyl group-containing polyester resin used is usually such that the molar ratio of the number of moles of glycidyl groups of the epoxy resin to the number of moles of carboxylic acid groups of the polyester resin is 0.4 to 3.0. ,Preferably
It is suitable that the amount is 0.5 to 2.0, particularly preferably 0.6 to 1.6. When this molar ratio is smaller than 0.4, it is difficult to develop a sufficient curing reaction. On the other hand, if the ratio is larger than 3.0, the coating film may be insufficiently cured, which is not preferable.

In the powder coating material of the present invention, a curing accelerator can be used in addition to the above-mentioned curing agent. Specifically, for example, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-.
Methylimidazole, 1-benzyl-2-methylimidazole, 2,4-diamino-6 (2′-methylimidazole (1 ′)) ethyl-s-triazine, 2,4-diamino-6 (2′-undecylimidazole (1 ')) Ethyl-s-triazine, 2,4-diamino-6 (2'-
Ethyl, 4-methylimidazole (1 ')) ethyl-s
Examples include imidazole derivatives such as -triazine and 2,4-diamino-6 (2'-methylimidazole (1 ')) ethyl-s-triazine / isocyanuric acid adduct. Preferably, 2,4-diamino-6 (2′-methylimidazole (1 ′)) ethyl-s-triazine is desirable. The compounding ratio of these curing accelerators is epoxy resin 1
It is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3.5 parts by weight, and still more preferably 100 parts by weight.
It is about 0.5 to 2.0 parts by weight. Examples of the epoxy resin having a naphthalene skeleton contained in the epoxy powder coating material of the present invention include EPICRON HP-4032 (manufactured by Dainippon Ink and Chemicals, Inc.) based on 1,6-didihydroxynaphthalene.

In addition to the above-mentioned components, the powder coating composition of the present invention may further contain, if necessary, colorants, rust preventive pigments, fillers, coupling agents, fluidity regulators, cissing preventives, anti-sagging agents and the like. The additive can be blended.

The powder coating composition of the present invention comprises an Henschel mixer, an epoxy resin, a curing agent, an epoxy resin having a naphthalene skeleton and, if necessary, a curing accelerator and other additives.
After dry-mixing by a disperser such as, a melt-kneading is performed by a disperser such as a twin-screw extruder, and then cooling, coarse pulverization, fine pulverization, and filtration (usually 100 mesh).

The powder coating material of the present invention can form a coating film by applying the powder coating to an object to be coated such as a general gold material and baking and curing it. In addition, surface treatment or the like can be performed on the article to be coated, if necessary. The powder coating can be performed by a powder coating method known per se, for example, electrostatic powder coating, triboelectric powder coating, uncharged powder coating, fluidized coating and the like.
The coating film thickness is not particularly limited, but is about 30 μm to 1 m
m, preferably in the range of about 50 μm to 500 μm.

[0020]

EXAMPLES Next, examples will be described in more detail.

Example 1 Epicort 1004 (manufactured by Japan Epoxy Resin Co., Ltd., trade name, bisphenol A / epichlorohydrin,
Epoxy equivalent 875 to 1025, molecular weight 1400, softening point 97 ° C.) 1000 g to adipic acid dihydrazide 52
g, 2,4-diamino-6 (2′-methylimidazole (1 ′)) ethyl-s-triazine 6 g, EPICRO
N HP-4032 (manufactured by Dainippon Ink and Chemicals, Inc., trade name), 50 g of carbon black, and 300 g of precipitated barium sulfate were mixed and dry-dispersed and mixed by a Henschel mixer, and then biaxial melt-mixed and dispersed. After cooling, coarse pulverization, fine pulverization, and filtration (150 mesh) were performed to obtain the thermosetting epoxy powder coating material of Example 1.

Example 2 In place of the epicot 1004 in Example 1, an epico
1004 and Epicort 1007 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd., trade name, bisphenol A / epichlorohydrin, epoxy equivalent 2000 to 2500, molecular weight 2900, melting point 127 to 133 ° C.) of 1/1 by weight ratio. A thermosetting epoxy powder coating material of Example 2 was obtained in the same manner as in Example 1 except that the above materials were used.

Example 3 Ester resin ER-8101 (manufactured by Unitika, trade name, acid value 62, number average molecular weight 2010) 600 g, Epicort 1002 (manufactured by Japan Epoxy Resin Co., Ltd.,
Trade name, bisphenol A / epichlorohydrin, epoxy equivalent 600 to 700, molecular weight 1400, softening point 78
(400C) 400 g, 2,4-diamino-6 (2'-methylimidazole (1 ')) ethyl-s-triazine 10
g, and 50 g of EPICRON HP-4032 (trade name, manufactured by Dainippon Ink and Chemicals, Inc.), 20 g of carbon black, and 300 g of precipitating barium sulfate were added and heat-cured in Example 3 in the same manner as in Example 1. A type epoxy powder coating was obtained.

Comparative Example 1 A thermosetting epoxy powder coating material of Comparative Example 1 was obtained in the same manner as in Example 1 except that 0 part of EPICRON HP-4032 was used.

COMPARATIVE EXAMPLE 2 In Example 2, EPICRON HP-4032
A thermosetting epoxy powder coating material of Comparative Example 1 was obtained in the same manner as in Example 2 except that 0 part of was used.

Comparative Example 3 In Example 3, EPICRO
A thermosetting epoxy powder coating material of Comparative Example 1 was obtained in the same manner as in Example 3 except that 0 part of N HP-4032 was used.

The results of Examples and Comparative Examples are shown in Table 1. Table 1

[Table 1]

In Table 1, performance tests of paints and coating films were conducted by the following methods.

Salt water spray resistance test: Conducted up to 2500 hours according to JIS K-5400. The degree of rust and blistering on the test piece was evaluated every 500 hours. ○ indicates that there is no rust or blisters, Δ indicates that rust or blisters are slightly generated, and inferior, and × indicates that rust or blisters occur abundantly.

[0030]

The powder coating material of the present invention provides a coating film having long-term corrosion resistance.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4J036 AA00 AA05 AC01 AC05 DA01                       DB15 DC02 DC31 DC35 DC41                       FB07 FB11 FB13 JA01 KA05                 4J038 DA042 DB041 DB052 DB061                       DB071 DB102 DB211 DB221                       DD042 JA35 JA63 JB01                       JB12 JB17 JB18 JB32 KA03                       MA13 MA14 NA03 PA02

Claims (3)

[Claims] 1. A melting point of 90 to 140 ° C. and an average molecular weight of 1,000.
˜4000, epoxy equivalent of 800 to 4000, and epoxy resin powder containing 100 parts by weight of epoxy resin powder containing a curing agent, 1 to 1 of epoxy resin having a naphthalene skeleton.
A thermosetting epoxy resin powder coating material containing 0 part by weight. 2. The curing agent is an amine-based curing agent, an acid-based curing agent,
At least one curing agent selected from acid anhydride curing agents, polyamide curing agents, phenolic hydroxyl group-containing curing agents, dicyandiamide curing agents, cationic polymerization reaction curing agents and hydrazine curing agents, The thermosetting epoxy resin powder coating material according to claim 1. 3. The thermosetting epoxy resin powder coating composition according to claim 2, wherein the acid-based curing agent is a carboxylic acid-containing polyester resin having an acid value of 20 to 90 mg KOH / g.