JPS583514B2 - Huntai Soyouji Yushisoseibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition for powder coating, and more particularly to a resin composition for powder coating comprising an imide ring-containing epoxy resin and an epoxy curing agent, which is coated by a powder coating method. The object of the present invention is to provide a resin composition for powder coating, which can easily form a film having excellent heat resistance, electrical insulation, mechanical properties, solvent resistance, etc. on the object to be coated.

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 found 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 this problem, we have found that conventionally, the introduction of heterocycles into epoxy resins has focused on increasing the melting point,
It was considered difficult to produce epoxy compounds due to the large drop in reactivity due to poor solubility, etc., but the present inventors have discovered that certain imide ring-containing derivatives are highly compatible with epoxy resins and react with them. The new quinazolone ring-containing epoxy resin obtained by this method has excellent thermal stability, and despite the introduction of heterocycles, it is compatible or mixable with commonly known curing agents, and can be easily made into a uniform resin. A composition is obtained, and the resin composition consisting of the imide ring-containing epoxy resin and the epoxy curing agent satisfies the above-mentioned drawbacks, can be used in powder form, and furthermore forms a thermosetting film having an insoluble and infusible network structure. The present invention was completed based on this finding.

Specifically, the present invention provides a compound having two quinazolone rings in one molecule, represented by the general formula (1) (wherein R is an aliphatic or aromatic divalent group),
An epoxy compound having at least two epoxy groups in one molecule is used when the number of epoxy groups in the epoxy compound is 2 to 2 relative to the number of hydroxyl groups in the compound containing a quinazolone ring.
This invention relates to a resin composition for powder coating, characterized in that it consists of a solid quinazolone ring-containing epoxy compound obtained by mixing and reacting in a ratio of 30 to 30% and an epoxy curing agent (B). be.

Generally, derivatives having a quinazolone ring are poorly soluble;
Conventionally, it has been considered difficult to introduce heterocycles into epoxy resins, but the quinazolone ring-containing dicarboxylic acid compound represented by the above general formula (I) has good compatibility with the epoxy resin JIa,
Furthermore, 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 bisphenol compound represented by the general formula (1) used in the present invention is 4,4'-
Using bisoxazinone obtained by acetylating diaminodiphenylmethane-3,3'-dicarboxylic acid with acetic anhydride or acetyl chloride as a starting material, 1 mole of the bisoxazinone and the general formula H2N-R- It is represented by OH (R is an aliphatic or aromatic divalent group).

For example, aminocarboxylic acid smol such as anthranilic acid, m-aminobenzoic acid, p-aminobenzoic acid, β-aminopropionic acid, γ-aminobutyric acid, glycine, etc.
Cresol can be easily obtained by heating with an organic solvent such as N,N-dimethylacetamide, N,N-dimethylformamide, or N-methylpyrrolidone at 80 to 220°C for 3 to 10 hours.

The epoxy resin used in the present invention is preferably solid at room temperature, and is a bisphenol A-type resin obtained by reacting 4,4'-isopropylidene diphenol (bisfufunol A) with shrimp chlorohydrin. It is a novolak-type epoxy resin obtained by reacting shrimp chlorohydrin with phenol novolak, cresol novolak, etc., and commercially available products include Epicote 1001 and Epicote 1 as bisphenol-type linear epoxy resins.
004, Epicote 1007, Epicote 1009, Epicote 1031, (all product names of Shell Chemical Co., Ltd.)
DER-6 6 1, DER-542 (both product names of Dow Chemical Company) Araldite ECN-1273, ECN as cresol novolak type epoxy resin
-1280 (all product names from Ciba Corporation), and others such as Chitsonox UNOX-207 (Chisso (JCC product name)) and Epicron iooo (product name from Inu Nippon Ink Co., Ltd.), which can be crushed and used alone or in combination of two or more. It can be used as appropriate.

In addition, as long as the resulting imide ring-containing epoxy resin is solid at room temperature, the above-mentioned epoxy resin that is solid at room temperature can be used in combination with an epoxy resin that is liquid at room temperature, such as Epicoat 828 (trade name of Shell Co., Ltd.). It is possible, and there is no problem in using 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 (1).

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 of the imide ring-containing dicarboxylic acid, the compatibility will be poor and the work will be difficult, and if it is more than 30, the compatibility will improve but the imide ring This is inappropriate because the heat resistance of the epoxy resin contained therein is not significantly improved.

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 hexahydrofucric 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, BF3 complex, and imidazole be blended in a range of 1 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 solid imide ring-containing epoxy resin (3) and the epoxy curing agent (B) 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., 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 bisphenol represented by the general formula (I) are shown.

[Example 1] 25.9 g (1 hydroxyl equivalent) of a quinazolone ring-containing bisphenol compound represented by the structural formula QP-1 and 6800 g of bisphenol A diglycidyl ether type epoxy (trade name Epicote 1009, manufactured by Shell Co., Ltd.) having an epoxy equivalent of 3400 ( 2 epoxy equivalent) and mix with 180-20
The reaction was carried out at 0° C. for about 1 hour to obtain a solid quinazolono ring-containing epoxy resin having an epoxy equivalent of 7,100.

7100 g of the quinazolone-containing epoxy resin ((1 epoxy equivalent) and 139 g of hexahydrophthalic anhydride
After mixing and pulverizing g (0.9 acid anhydride equivalent) in a ball mill, 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 2.
A cured resin coating of 50 microns was obtained.

This coating film was tested with a DuPont type impact tester (load: 500 g, center of impact 1/4 inch), and the result was 25 F, and the cross test was also good.

The Erichsen test was for 5 minutes.

Further, the weight loss of the cured resin after 500 hours at 200° C. in air was 4.2%.

[Example 2] Quinazolone phenol 25 represented by the structural formula QP-2
．． 9 g (0.1 hydroxyl equivalent) and epoxy equivalent 23
690 g (3.0 epoxy equivalent) of Novolac type epoxy (trade name: Ciba Araldite ECN-1280) of No. A quinazolone ring-containing epoxy resin was obtained.

After mixing and pulverizing 100 g of the quinazolone ring-containing epoxy resin and 7 g of dicyandiamide using a ball mill, this powder composition, which was sieved to 350 microns, was used to form a copper plate with a width of 30 mm, a thickness of 2.5 mm, and a length of 45 cm. A coating film was formed 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 250 microns thick, smooth and glossy.

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

Further, the weight loss of this cured resin after 500 hours at 200° C. in air was about 6.1%.

[Example 3] Quinazolone phenol represented by structural formula QP-3 25.
Bisphenol A diglycidyl ether type upoxy with 9 g (0.1 hydroxyl equivalent) and epoxy equivalent of 450 (
450g (1
0 epoxy equivalent) and heated at 180 to 200℃ for about 2
The reaction was carried out for a period of time to obtain a solid quinazolone ring-containing epoxy resin having an epoxy equivalent of 530.

100 g of the quinazolone ring-containing epoxy resin, epoxy curing agent BF3-400 (trade name of Harshaw Chemical Company) 6
g and 5 g of polyvinyl butyral resin as a flow regulator were mixed and pulverized using a ball mill, and then sieved to 350 microns to obtain a powdered crossfat composition.

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

This was heat-treated at 220°C for 30 minutes to obtain a cured resin coating film with a thickness of 300 microns.

The volume resistivity of this coating film under normal conditions is 7.1×1016Ω
cm and 2.8 x 1015 Ωc after 24 hours of hot water immersion.
m, and the breakdown voltage at normal time is 17.9KV10.1mm,
After 24 hours of hot water immersion, 16. The OKV was 10.1 mm.

Furthermore, the weight loss of the cured resin obtained in the same manner after 500 hours at 200°C was 5.8%.

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 has excellent heat resistance, electrical insulation, mechanical properties, and other properties. Because of its excellent properties, it is extremely advantageous industrially.

[Example 4] 259 g of a quinazolone phenol compound represented by the structural formula QP-1 (1 hydroxyl group equivalent) and a bisphenol A diglycidyl ether type epoxy compound having an epoxy equivalent of 480 (
960g (2.
A solid quinazolone ring-containing epoxy resin having an epoxy equivalent of 1220 was obtained by reacting at 180 to 200°C.

The mixture was mixed with 8 g of the epoxy curing agent Anchor 1040 (trade name of Anchor Chemical) using a ball mill, pulverized, and then sieved to 350 microns.

Next, preheat to 200℃ and size 20cm x 15cm x 0
．． The powder composition was sprayed onto a 3 cm copper plate using a spray gun to form a continuous molten coating film on the copper plate, which was then heat treated at 180°C for 30 minutes to form a cured coating film with a thickness of 200 microns. was gotten.

An impact test similar to Example 1 on this coating was carried out at 23c.
m, Erichsen test 4 mm.

The cross-cut test was also good.

Further, the weight loss of this cured resin after 500 hours at 200° C. in air was about 0.8%.

Claims (1)

[Claims] 1 General formula (wherein R represents an aliphatic or aromatic divalent group)
, is indicated by . A compound having two quinazolone rings in one molecule and an epoxy compound having at least two epoxy groups in one molecule are calculated based on the number of carboxyl groups in the compound containing a quinazolone ring. The number of
A resin composition for powder coating, comprising a solid quinazolone ring-containing epoxy resin (B) obtained by blending and reacting in a ratio of 1 to 30% and an epoxy curing agent (B).