JPS583511B2 - Huntai Soyouji Yushisoseibutsu - Google Patents

Description

[Detailed description of the invention] The present invention relates to a resin composition for powder coating.

More specifically, it relates to a resin composition for powder coating consisting of an imide ring-containing epoxy resin and an epoxy curing agent, which can be coated by a powder coating method to provide heat resistance, electrical insulation, mechanical properties, etc. The object of the present invention is to provide a resin composition for powder coating that can easily form a film with excellent solvent resistance.

Conventionally, the most commonly used resin for powder coating is epoxy resin, but although epoxy resin has excellent electrical insulation and mechanical properties, it is not always satisfactory in terms of heat resistance. It's not something you can do.

On the other hand, heterocyclic polymers such as polyimide resin, polyamideimide resin, polyesterimide resin, polybenzimidazole resin, and polyhydantoin resin are well known as heat-resistant resins. However, due to its high melting point, it is unsuitable as a powder coating resin.

Therefore, the present inventors proposed that if a resin composition for powder coating that gives a cured product with excellent electrical properties, mechanical properties, chemical resistance, and heat resistance could be obtained, all of the above drawbacks could be solved. As a result of various studies aimed at solving these problems, we found that conventionally, the introduction of heterocycles into epoxy resins resulted in a significant decrease in reactivity due to higher melting points and less solubility, making it virtually impossible to manufacture epoxy compounds. Although it was thought to be difficult, the present inventors discovered that a certain type of imide ring-containing derivative is well compatible with epoxy resin, and the new quinazolone ring-containing epoxy resin obtained by the reaction has excellent thermal stability. Moreover, despite the introduction of a heterocycle, it is compatible or mixable with commonly known curing agents, and a uniform resin composition can be easily obtained.
The present inventors have discovered that a resin composition comprising the imide ring-containing epoxy resin and an epoxy curing agent satisfies the above-mentioned drawbacks, can be used in powder form, and can provide an insoluble and infusible thermosetting film with a network structure. The invention was completed.

That is, the present invention relates to a dicarboxylic acid compound having two quinazolone rings in one molecule, represented by the general formula (I) (wherein R is an aliphatic or aromatic divalent group), and a dicarboxylic acid compound having two quinazolone rings in one molecule. and an epoxy compound having at least two epoxy groups in a ratio in which the number of epoxy groups in the epoxy compound ranges from 2 to 30 to the number of carboxyl groups in the compound containing a quinazolone ring, and the mixture is reacted. The present invention relates to a resin composition for powder coating, which is characterized by comprising a solid quinazolone ring-containing epoxy resin obtained by the above method and an epoxy curing agent (B).

In general, derivatives with quinazolone rings are poorly soluble, and it has traditionally been difficult to introduce heterocycles into epoxy resins.
The quinazolone ring-containing dicarboxylic acid compound represented by the above general formula (I) has good compatibility with epoxy resins, and
It has reactivity with epoxy resins, and the quinazolone ring-containing epoxy resin of the present invention can be easily obtained.

The quinazolone ring-containing biscarboxylic acid compound represented by the general formula (I) used in the present invention is 4,4'-
The bisoxazinone obtained by acetylating diaminodiphenylmethane-3,3' dicarboxylic acid with acetic anhydride or acetyl chloride, etc. is used as a starting material, and the nomol of the bisoxazinone and the general formula H
2N-R-COOH (R is an aromatic or aliphatic divalent group) such as anthranuric acid m-aminobenzoic acid, p-aminobenzoic acid, β-aminopropionic acid, γ-aminebutyric acid , an aminocarboxylic acid such as glycine with an organic solvent such as m-cresol, N,N-dimethylacetamide, N,N-dimethylformamide, or N-methylpyrrolidone at 80-220°C.
It can be easily obtained by heating for ~10 hours.

In addition, the epoxy resin used in the present invention is preferably solid at room temperature, and is a linear bisphenol A type obtained by reacting 4,4'-isopropylidene diphenol (bisphenol A) with shrimp chlorohydrin. Epoxy resin or phenol novolak,
It is a novolak-type epoxy resin obtained by reacting cresol novolak etc. with epichlorohydrin. Commercially available products include Epicoat 1007 and Epico-1100 as bisphenol-type linear epoxy resins.
9. Epikote 1031 (all trade names from Shell Chemical Co.), DER-661, DER-542 (all trade names from Dow Chemical Co.), Araldite ECN-1273, ECN-1 as cresol novolac type epoxy resins
280 (all Ciba product names), and Chitsonox UNOX-207 (Chisso (JCC product name)).
Ebicuron 1000 (trade name, Inu Nippon Ink Co., Ltd.) and the like can be pulverized and used alone or in a mixture of two or more as appropriate.

Furthermore, if the resulting imide ring-containing epoxy resin is solid at room temperature, it can be used in combination with the above-mentioned epoxy resin that is solid at room temperature and an epoxy resin that is liquid at room temperature, such as Epicote 828 (trade name of Shell Co., Ltd.). However, there is no problem in using the liquid epoxy resin alone.

The imide ring-containing epoxy resin in the present invention can be produced by reacting the epoxy resin with the imide ring-containing dicarboxylic acid compound represented by the general formula (I).

Excellent results can be obtained when the reactant is used in a range where the number of epoxy groups in the epoxy resin ranges from 2 to 30 per carboxyl group of the imide ring-containing dicarboxylic acid.

If the number of epoxy groups in the epoxy resin is less than 2 for one carboxyl group in the imide ring-containing dicarboxylic acid, the compatibility will be poor and the work will be difficult. The heat resistance of the imide ring-containing epoxy resin is not significantly improved, so it is unsuitable.

Although the reaction is advantageously carried out by heating the reactants between 90 and 250C, it is preferred to carry out the reaction at a temperature of 130 to 230C.

Although the reaction proceeds without a catalyst, a small amount of an aliphatic tertiary amine that does not contain active hydrogen, or a small amount of potassium carbonate or sodium carbonate can be added to start the reaction more easily. The addition of does not reduce the effect of the present invention in the slightest.

Further, in order to accelerate the reaction, an appropriate amount of an organic polar solvent such as dimethyl sulfoxide, N,N-dimethylacetamide, or N,N-dimethylformamide may be added.

Further, as the epoxy curing agent that can be used in combination with the present invention, any solid epoxy curing agent that is generally used as an epoxy curing agent may be used, such as trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride (THP), etc.
A), acid anhydrides such as hexahydrophthalic anhydride (HHPA) and phthalic anhydride, diaminodiphenylmethane,
Amines such as diaminodiphenylsulfone, Anchor 1040 (trade name of Anchor Chemical Company), BF3-40
BF3 complexes such as 0 (trade name of Harshaw Chemical Co.), carboxylic acids, imidazoles, polyamides, polysulfides, dicyandiamide, etc. can be used alone or in combination as appropriate.

The amount of these epoxy curing agents varies depending on the type of curing agent, but it is recommended that dicyandiamide, BF2 complex, and imidazole be blended in the range of j to 10 parts by weight per 100 parts by weight of the imide ring-containing epoxy resin. Preferably, acid anhydrides, amines, etc. are appropriately blended in an arbitrary range commonly used for the epoxy equivalent of the imide ring-containing epoxy resin (an amount corresponding to 80 to 100% of the epoxy equivalent).

The above-mentioned solid imide ring-containing epoxy resin (A) and epoxy curing agent are powdered and then mixed into a uniform mixture using a stirrer such as a ball mill or a ribbon mixer.

It is a polymerization catalyst that can be mixed uniformly even in liquid form.

Alternatively, these may be melted and mixed using a roll, kneader, etc., and then ground using a grinder and sieved to obtain a composition with a desired particle size.

Furthermore, if necessary, a flow control agent such as polyvinyl butyral, a filler such as silica, calcium carbonate, and titanium oxide, a coloring agent, a plasticizer, etc. may be added during mixing to form a resin composition.

The particle size of the resin composition is preferably 350 microns or less,
If it is less than 50 microns, it is not preferable because dust tends to stand up during painting.

Since the resin composition for powder coating of the present invention is thermosetting, it is cured after being melted at a temperature equal to or higher than the melting point by applying heat.

The curing temperature varies depending on the melting point of the resin component and the type and amount of the catalyst, but is approximately 130 to 220°C.

For example, the object to be coated is heated in advance to a temperature higher than the melting point of the resin component in the composition, and a powdered resin composition is melted and coated on the object, and then this is heated afterward to completely cure the object.

The resin composition does not contain any components that volatilize during heat curing,
Furthermore, since no volatile products are produced during the curing reaction, a film with a smooth surface, toughness, and excellent heat resistance, electrical insulation, mechanical properties, and chemical resistance can be obtained.

The resin composition of the present invention can be easily coated onto various objects using various powder coating methods, such as fluidized dipping, electrostatic powder coating, thermal spraying, and spray coating.

Next, the present invention will be specifically explained with reference to Examples.

In the examples, the structural formula and abbreviation of the quinazolone ring-containing dicarboxylic acid compound represented by the general formula (I) are shown.

[Example 1] Quinazolone dicarboxylic acid 28 represented by structural formula QA-1
6 g (1 acid equivalent) and 3400 g (1 epoxy equivalent) of bisphenol A diglycidyl ether type epoxy (trade name Shell Epicote 1001) having an epoxy equivalent of 3400 and bisphenol A diglycidyl ether type epoxy (trade name Shell Epicor
828) and 190 g (1 epoxy equivalent) of
React at 80 to 200°C for about 2 hours until the epoxy equivalent is 388.
A solid quinazolone ring-containing epoxy resin of 0 was obtained.

The imide ring-containing epoxy resin 3880 (1 epoxy equivalent) and hexahydrophthalic anhydride 139 g (0.
9 acid anhydride equivalents) using a ball mill, and after pulverizing 3
It was sieved to 50 microns.

A copper plate with a thickness of 3 mm, which had been preheated to 200°C using this powder composition using the fluidized dipping method, was immersed in the floating powder for about 15 seconds, and then heated at 180°C for 15 minutes, resulting in an average film thickness of 25.
A cured resin coating film of 0 micron was obtained.

This coating film was tested with a DuPont impact tester (load: 500 g, center of impact 1/4 inch), and the result was 21 degrees, and the cross test was also good.

Erichsen test was 6 mm.

Furthermore, the weight of this cured resin decreased by about 2.6% after 500 hours at 200° C. in air.

[Example 2] Quinazolone carboxylic acid 28 represented by structural formula QA-2
．． 6 g (0.1 acid equivalent) and 690 g (3.0 epoxy equivalent) of a novolac type epoxy with an epoxy equivalent weight of 230 (trade name Ciba Araldite, ECN-1280) were mixed and heated at 180 to 200°C. The reaction was carried out for 1 hour to obtain a solid quinazolone ring-containing epoxy resin having an epoxy equivalent of 250.

100 g of the quinazolone ring-containing epoxy resin and 7 g of dicyandiamide were mixed and ground using a Pall mill, and then sieved to 350 microns.

Using this powder composition, a width of 30 mm%, a thickness of 2.5 mm, and a length of 45 cm. A coating film was formed on a steel plate using an electrostatic powder coating method.

This was heated at 220° C. for 30 minutes to cure the coating film.

The coating film formed was approximately 200 microns thick, smooth and glossy.

An electrical spark test at 10 KV revealed no defects in the coating.

Moreover, the weight loss of this cured resin after 500 hours at 200° C. in air was about 5.4%.

[Example 3] 22.4 g (0.1 acid equivalent) of a quinazolone carboxylic acid compound represented by the structural formula QA-3, an epoxy equivalent, and a bisphenol A diglycidyl ether type epoxy with an epoxy equivalent of 450 (trade name: Dow Chemical Company) DER-661
) with 450g (1 equivalent amount of epoxy) and 180~
The reaction was carried out at 200°C to obtain a solid quinazolone ring-containing epoxy resin with an epoxy equivalent of 530.

100 g of the quinazolone ring-containing epoxy resin and epoxy curing agent Anchor 1040 (Anchor Chemical brand name)
8 g was mixed and ground using a whole mill, and then sieved to 300 microns.

Next, preheat to 200℃ and size 20cm x 15cm x 0
．． After forming a continuous molten coating on a 3cm copper plate,
This was heat-treated at 180°C for 30 minutes to obtain a cured resin coating film with a thickness of 200 microns.

An impact test similar to Example 1 on this coating was conducted at 25c.
m, Erichsen test was 5 mm.

Moreover, the cross-cut test was also good.

Moreover, the weight loss of this cured resin after 500 hours at 200° C. in air was about 5.0%.

[Example 4] 280 g (1 acid equivalent) of a quinazolone carboxylic acid compound represented by the structural formula QA-1 and 960 g (2 Epoxy equivalent) were mixed and reacted at 180 to 210°C for about 2 hours to obtain a solid quinazolone ring-containing epoxy resin with an epoxy equivalent of 1260.

100 g of the quinazolone ring-containing epoxy resin, epoxy curing agent BF3-400 (trade name of Harshaw Chemical Company)
7g and flow control agent polyvinyl butyral resin 5g
were mixed and pulverized using a ball mill, and then sieved to 320 microns to obtain a powdered resin composition.

Next, preheat to 200℃ and size 20cm x 15cm x 0
．． A coating film was formed on a 2 cm steel plate by a fluidized dipping method.

This was heat-treated at 220℃ for 30 minutes, and the thickness was 300℃.
A micron cured resin coating was obtained.

The volume resistivity of this coating film under normal conditions is 4.2×1016
Ωcm, and the breakdown voltage under normal conditions is 20. OKV/0.1
mm, 16.1KV/0. after 24 hours immersion in hot water. 1
It was mm.

In addition, cured resin obtained in the same manner was heated at 200°C and 500°C.
Weight loss after hours is 0. It was 7%.

Furthermore, no defects were observed in the coating film even after immersion in a 5% hydrochloric acid aqueous solution and a 5% caustic soda aqueous solution for 10 hours.

As mentioned above, the resin composition for powder coating according to the present invention can be easily coated on various objects by various powder coating methods, and the cured product thereof has excellent heat resistance, electrical insulation, mechanical properties, etc. Therefore, it is extremely advantageous industrially.

Claims (1)

[Claims] 1. A dicarboxylic acid compound having two quinazolone rings in one molecule represented by the general formula (in the formula, R represents an aliphatic or aromatic divalent group); An epoxy compound having at least two epoxy groups is blended in a ratio in which the number of epoxy groups in the epoxy compound ranges from 2 to 30 to the number of carboxyl groups in the compound containing a quinazoene ring, and the reaction is performed. A resin composition for powder coating, comprising a solid imide ring-containing epoxy resin composition N and an epoxy curing agent (B).