JPS62285966A - Epoxy resin powder coating composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. having excellent flexibility, adhesion and resistance to water and boiling water, consisting of a specified poly(di) glycidyl ether compsn. and a curing agent for epoxy resin. CONSTITUTION:An epoxy resin of formula I (wherein n is a number of 0-3) is reacted with bisphenol A, etc. in the presence of a catalyst (e.g., a tert. amine) at 50-140 deg.C for 2-5hr to obtain a poly(di)glycidyl ether compd. (A) having a 4,4'-bis-3,3'-5,5'-tetramethylbiphenol skeleton introduced thereinto and an average MW of not lower than 900, represented by formulas II and/or III (wherein X is H or halogen; Y is H or CH3; and l, m and n are each not smaller than 0). The component A is blended with a curing agent (B) (e.g., a phenolic novolak) for epoxy resin and optionally a filler (e.g., TiO2), a colorant, a curing accelerator, a thixotropic agent, a flow modifier, etc. (C). The mixture is melt- kneaded at 70-140 deg.C, cooled and crushed.

Description

Detailed Description of the Invention (,) Object of the Invention (Industrial Application Field) The present invention has excellent adhesion, flexibility and water resistance, and particularly has excellent boiling water resistance (boiling water leaching resistance and boiling water resistance). The present invention relates to an epoxy resin powder coating composition that provides a coating film with excellent adhesion after water treatment.

(Prior art) Epoxy resins are widely used in various fields such as paints, electricity, civil engineering, architecture, and adhesives due to their excellent properties. In particular, epoxy resin powder coatings are pollution-free, resource-saving, and energy-saving. As paints, they are gradually replacing conventional solvent-based paints.

Conventional general epoxy resin powder coatings are made by combining a condensation reaction product of bisphenol A and epihalohydrin with an epoxy resin curing agent, and adding various fillers, pigments, flow control agents, etc., and melt-mixing the mixture. The crushed one is used. In this type of epoxy resin powder coating, various efforts have been made to achieve a well-balanced formulation of various properties such as flexibility, adhesion, and water resistance. In particular, in applications where water resistance is important, water resistance can be improved by lowering the molecular weight of the epoxy resin and increasing the crosslinking density during curing. There was a drawback that the value decreased.

(Problems to be Solved by the Invention) In view of the above-mentioned circumstances, the present invention provides an epoxy resin powder that provides a coating film with excellent water resistance, particularly boiling water resistance, while maintaining flexibility and adhesion. The aim is to provide paint.

(b) Structure of the Invention (Means for Solving the Problems) As a result of repeated research in order to solve the above-mentioned problems, the present inventor has developed an epoxy compound for epoxy resins.
, 4'-bis-3,3'-5,5'-tetramethylbiphenol skeleton was introduced using a specific polydiglycinolether compound.

That is, the epoxy resin powder coating composition of the present invention has the general formula (wherein, X is H or a halodane atom, and Y is H or C
H3, and t+m and n are each integers of 0 or more. ) A poly-zogcinol ether compound having an average molecular weight of 900 or more and/or a general formula (wherein, X is H or a halodane atom, Y is H or (IH, and t+
m and n are each integers of 0 or more. ) A composition containing a polydiglycinol ether compound having an average molecular weight of 900 or more and (B) an epoxy resin curing agent.

The polydiglycidyl ether compound (4) having an average molecular weight of 900 or more in the present invention may be only a compound represented by the general formula (1), or may be a compound represented by the general formula (]I
It may be only the compound represented by I, or it may be a mixture of the compound represented by the general formula (1) and the compound represented by the general formula (II).

The I-diglycidyl ether compound having an average molecular weight of 900 or more used in the present invention can be produced by various methods, and the following two methods are representative methods.

The first method is, for example, bisphenol An xt
s-oxy resin, bisphenol F type epoxy resin or brominated bisphenol A type epoxy resin, etc. and 4,4'-
Bis-3,3'-5,5'-tetramethylbiphenol is heated at 120 to 190°C by adding tertiary amines, imidazoles, quaternary ammonium salts, etc. as a catalyst.
This is a method of reacting for ~5 hours.

As the bisphenol A type epoxy resin used in this case, for example, Epicoat 828. Epicote 1001
(Product name of Yuka Shell Epoxy Co., Ltd.) etc.
As the bisphenol F type epoxy resin, for example, Epicote 8o7 (trade name of Yuka Shell Epoxy Co., Ltd.)
Examples of brominated bisphenol A epoxy resins include Epicote 5050 and Epicote 5051F.
' (both are trade names of Yuka Ciel Epogishi Co., Ltd.) are representative examples.

In addition, the second method uses an epoxy resin represented by the general formula (in the formula, n is an integer of 0 to 3) and, for example, bisphenol A1, bisphenol F, or tetrabromobisphenol A, etc. as a catalyst. 120-190 by adding class amines, imidazoles or quaternary ammonium salts, etc.
This is a method of reacting at ℃ for 2 to 5 hours. An example of the epoxy resin represented by the general formula (g) used in this case is Epicoat YX4000 (trade name of Yuka Ciel Ekishi Co., Ltd.).

The above-mentioned polydiglycidyl ether compounds having an average molecular weight of 900 or more used in the present invention each have a melting point generally in the range of 50 to 140°C, preferably 70 to 120°C.

In the present invention, it is possible to use a relatively small amount of other epoxy compounds in combination with the above-mentioned polydiglycidyl ether compound having an average molecular weight of 900 or more within a range that does not significantly impair the cured properties of the composition of the present invention. Also, an epoxy compound obtained by reacting a monophenol compound with a part of the terminal epoxy group of a poly-diglycidyl ether compound having an average molecular weight of 900 or more represented by the general formula (1) and/or (It) Small amounts of the compounds can also be used together. A poly-diglycidyl ether compound containing such an epoxy compound can be obtained by adding a small amount of a monophenol compound to the reaction system during the manufacturing process of the poly-diglycidyl ether compound.

Various kinds of epoxy resin curing agents (B) can be used in the present invention. Examples include novolac type phenolic resins, bisphenol Aq phenolic resins, dicyandiamide, imidazoles, hydrazides, polyester resins, aromatic amines, and acid anhydrides. Two or more of these curing agents can also be used in combination in the present invention.

The epoxy resin powder coating composition of the present invention may contain one of various additives that are included in ordinary epoxy resin powder coatings, if necessary. Examples of such additives include titanium oxide, Merck, red iron oxide,
Fillers such as silica, mica, calcium carbonate, alumina, etc., coloring agents such as seed image pigments, hardening accelerators, seed modification agents, flow regulators, and the like can be mentioned.

The powder coating composition of the present invention can be prepared by various methods, but the typical preparation method is as described above. Mix the lysiglycidyl ether compound (■), the epoxy resin curing agent (B), and appropriate additives to be added as necessary, and melt at a temperature of about 70 to 140°C using a heated knee goo, heated roll, extrusion goose, etc. An example is a method of kneading, cooling, and then pulverizing.

(Examples etc.) Below, epoxy resin production examples, examples, and comparative examples are given and further detailed. "Parts" in these examples mean "parts by weight" unless otherwise specified.

Epoxy resin manufacturer Individual epichlorohydrin-bisphenol A epoxy resin (Yuka Shell Epoxy Co., Ltd. trade name Ebiko) 828
, epoxy equivalent 187) 100 parts and 4,4'-bis-3,3'-5,5'-tetramethylbiphenol 4
To 2 parts, 0.03 part of 2-methylimidazole was added as a catalyst, and the mixture was reacted at 170°C for 3 hours to obtain an epoxy resin having an epoxy equivalent of 770 and an average molecular weight of 1800, which was solid at room temperature. This is called "epoxy resin-containing."

Epoxy resin production example B 4. 100 parts of diglycidyl ether of 4'-bis-3,3'-5,5'-tetramethylbiphenol (trade name Epicote YX4000, Epoxy 1186, Yuka Ciel Epoxy Co., Ltd.) and bisphenol Add 0.0 of tetramethylammonium iodide as a catalyst to 40 parts of A.
3 parts were added and reacted at 170° C. for 3 hours to obtain an epoxy resin having a knee equivalent weight of 780 and an average molecular weight of 1400, which was solid at room temperature. Hereinafter, this will be referred to as "epoxy resin B"
That's what it means.

Epoxy resin production example C The same 4,4 used in Nyxy resin spreading example B
100 parts of diglycidyl ether of '-bis-3,3'-5,5'-tetramethylbiphenol, 35 parts of bisphenol A, and 5 parts of nonylphenol, and 2-
Add 0.03 parts of methylimidazole and heat at 170°C.
After reacting for a period of time, a Nixi resin having an epoxy equivalent weight of 700 and an average molecular weight of 1500 was obtained. Hereinafter, this will be referred to as "epoxy resin C."

Example 1 100 parts of epoxy resin A, 4 parts of zocyandiamide as a curing agent, and 0.2 parts of 2-ethyl-4-methylimidazole (manufactured by Yuka Shell Epoxy Co., Ltd.) as a reaction accelerator.
1 part, 30 parts of titanium oxide as a pigment, 15 parts of red iron oxide, and 1 part of Acronal 4F (manufactured by BASF Japan Co., Ltd.) as a flow regulator were added, kneaded in a kneader at 90°C for 1 minute, cooled, and pulverized. A powder coating was obtained.

This powder coating was applied to a mild steel plate using an electrostatic sprayer, and
The performance of the coating film obtained by baking at a temperature of 0° C. for 20 minutes was investigated. The results were as shown in Table 1.

Example 2 8100 parts of epoxy resin was added with polyester resin (trade name: Finedic M-61, Inu Nippon Ink Co., Ltd.) as a curing agent.
04) Add 35 parts of titanium oxide, 30 parts of titanium oxide, 15 parts of red iron oxide, and 1 part of flow regulator Acronal 4F (manufactured by BASF Japan Co., Ltd.), and knead and crush in the same manner as in Example 1 to obtain a powder coating. Ta.

This paint was applied and baked in the same manner as in Example 1, and the film performance obtained was as shown in Table 1.

Example 3 Using epoxy resin C as the epoxy resin, a powder coating was manufactured in the same manner as in Example 1, and this coating was applied and baked in the same manner as in Example 1. were as shown in Table 1.

Comparative Example 1 A powder coating was prepared in the same manner as in Example 1, except that instead of epoxy resin A, bisphenol A type epoxy tree W having an epoxy equivalent of 790 (trade name Epicote 1003F, manufactured by Yuka Shell Epoxy Co., Ltd.) was used. It was coated and baked in the same manner. The coating film performance was as shown in Table 1.

Comparative Example 2 A powder coating was prepared in the same manner as in Example 2, except that instead of epoxy resin B, a bisphenol A type epoxy resin having an ebay equivalent of 920 (trade name Epicoat 1004, manufactured by Yuka Shell Epoxy Co., Ltd.) was used. Then, it was applied and baked in the same way. The coating film performance was as shown in Table 1.

Table 1 Notes to Table 1: The test method and evaluation are as follows.

Book 1...Visual judgment O Good X Bad *2... Extrude 71 using an Erichsen tester.

ONo abnormality.

× There are abnormalities such as cracks.

*3...Dupont impact testing machine (impulsion core inch x load 1 kg x height 50c!n) O
No abnormalities.

× There are abnormalities such as cracks.

*4...Goban eyes close contact chishibakuri (1 gourd x 100/100) ONo abnormality.

× There is peeling of the paint film.

*5: Immersed in boiling water at 98 to 100°C for 90 minutes. Visual judgment: ○ No abnormalities.

Δ There are some abnormalities such as gloss.

X: There are significant abnormalities such as gloss.

*6: After immersing in boiling water at 98-100°C for 90 minutes, peel off the gourd adhesive tape (1 gourd x 100/100) ○ No abnormality.

× Peeling off the entire surface of the paint film (c) Effect of the invention The epoxy resin powder coating composition of the present invention provides a paint film that is excellent in water resistance, flexibility, and adhesion, and particularly has outstanding water repellency when applied. Can be done. Moreover, this coating composition does not cause blocking even during long-term storage at room temperature or during transportation, and has excellent storage stability.

Patent applicant Yuka Shell Epoxy Co., Ltd. Agent Patent attorney Moriya Nakatani 7・□゛・1. ′
.

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Claims (1)

[Claims] 1) (A) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, X is H or a halogen atom, Y is H or C
H_3, and l, m, and n are each integers of 0 or more. ) Polyglycidyl ether compounds with an average molecular weight of 900 or more and/or general formulas ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, X is H or a halogen atom, and Y is H or C
H_3, and l, m, and n are each integers of 0 or more. ) An epoxy resin powder coating composition comprising a polydiglycidyl ether compound having an average molecular weight of 900 or more and (B) an epoxy resin curing agent.