JPS583512B2 - 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 necessary in terms of heat resistance. Sushi is also not satisfying.

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 was unsuitable as a powder coating resin.

Therefore, the inventors of the present invention have found that if a resin composition for powder coating can be obtained that provides a cured product with excellent electrical properties, mechanical properties, chemical resistance, and heat resistance, all of the above-mentioned drawbacks can be solved. As a result of various research aimed at solving such problems,
Conventionally, the introduction of heterocycles into epoxy resins has been considered difficult to produce epoxy compounds due to a large drop in reactivity due to higher melting points and less solubility, but the present inventors have The imide ring-containing derivative is well compatible with the epoxy resin, and the new imide ring-containing epoxy resin obtained by the reaction has excellent thermal stability, and despite the introduction of a heterocycle, it is different from the normally known epoxy resin. It is well compatible with or mixed with the curing agent, a uniform resin composition can be easily obtained, the resin composition consisting of the imide ring-containing epoxy resin and the epoxy curing agent satisfies the above drawbacks, and can be used in powder form. The present inventors have discovered that it is possible to obtain a thermosetting film having a network structure that is insoluble and infusible, and have completed the present invention.

That is, the present invention is represented by the general formula (1) (wherein R is an aliphatic or aromatic divalent group).

A carboxylic acid compound having two imide 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 an imide ring. For powder coating, comprising a solid imide ring-containing epoxy resin (A) obtained by mixing and reacting a solid imide ring-containing epoxy resin (A) with an epoxy group number in the range of 5 to 40, and an epoxy curing agent (B). The present invention relates to a oleaginous composition.

In general, derivatives having an imide ring are poorly soluble, and it has been difficult to introduce an imide ring into an epoxy resin. However, the imide ring-containing dicarboxylic acid compound represented by the above general formula (1) is compatible with epoxy resins. Furthermore, it has reactivity with epoxy resins, and the imide ring-containing epoxy resin of the present invention can be easily obtained.

The imide ring-containing biscarboxylic acid compound represented by the general formula used in the present invention is composed of penzophenonetetracarboxylic acid anhydride or nomol of penzophenonetetracarboxylic acid and the general formula H2N-R-COOH (R is aromatic or aliphatic divalent group), such as anthranilic acid, m-aminobenzoic acid, p-aminobenzoic acid,
It can be easily synthesized from smols of aminocarboxylic acids such as β-aminopropionic acid, γ-aminobutyric acid, and glycine.

This reaction can be carried out by a method in which even in a reaction system in which an excess of aminocarboxylic acid is added, the aminocarboxylic acid is removed as unreacted aminocarboxylic acid.

That is, specified amounts of reaction components are m-cresol, N,N-dimethylformamide, N,N-dimethylacetamide,
The reaction can be easily achieved by placing the mixture in a suitable reaction vessel with an organic solvent such as N-methylpyrrolidone or tetrahydrofuran and heating 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 linear epoxy resin obtained by reacting 4,4'-isopropylidene diphenol (bisphenol A) with shrimp chlorohydrin. It is a novolak-type epoxy resin obtained by reacting a resin, phenol novolak, cresol novolak, etc. with epichlorohydrin, and commercially available bisphenol-type linear epoxy resins include Epicote 1001, Epicote 1004,
Epicote 1007, Epicote 1009, Epicote 1031 (all product names of Shell Chemical Co., Ltd.) DER-
6 6 1, DER-5 4 2 (all product names of Dow Chemical Company), Araldite ECN-1 2 7'3-, E as a cresol novolak type epoxy resin
CN-1 2 8 0 (both are Ciba product names), and Chitsonox UNOX-207 (Chitso U
CC (trade name), Epicron 1000 (trade name, Inu Nippon Ink Co., Ltd.), etc., and they can be crushed and used alone or in a mixture of two or more as appropriate.

Furthermore, if the obtained imide ring-containing epoxy resin is solid at room temperature, the above-mentioned epoxy resin that is solid at room temperature may be used in combination with an epoxy resin that is liquid at room temperature, such as Epikote 828 (trade name of Shell Co., Ltd.). It is possible, and there is no problem even if the liquid epoxy resin is used alone.

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

Excellent results can be obtained when the reactant is used in an epoxy resin in which the number of epoxy groups in the epoxy resin ranges from 5 to 20 per one imide ring-containing dicarboxylic group.

If the number of epoxy groups in the epoxy resin is 5 or less for one carboxyl group in the imide ring-containing dicarboxylic acid, the compatibility will improve, but the resulting imide ring-containing epoxy resin will not have much improvement in heat resistance, so it is unsuitable. It is.

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 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 does not reduce the effectiveness of the invention in any way.

Further, in order to accelerate the reaction, an appropriate amount of a 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), hexahydrophthalic anhydride (HHPA), acid anhydrides such as phthalic anhydride, diaminodiphenylmethane,
Amines such as diaminodiphenylsulfone, Anchor 1040 (trade name of Anchor Chemical Company) BF3-400
BF3-based complexes such as (Harshaw Chemical Co., Ltd. product name),
Carboxylic acids, imidazoles, polyamides, polysulfides, dicyandiamide, and the like 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 above-mentioned solid imide ring-containing epoxy resin (A) and 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., 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, lucium carbonate, or 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.

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

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 coating 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 addition, in the examples, the structural formula and abbreviation of the imide ring-containing dicarboxylic acid compound represented by the general formula (1) are shown.

[Example 1] 280 g (1 acid equivalent) of an imide ring-containing dicarboxylic acid compound represented by the structural formula BTDI-1 and an epoxy equivalent of 3400
3400 of bisphenol A diglycidyl ether type epoxy (product name Shell Co., Ltd. Epicote 1009)
g (1 epoxy equivalent) and 760 g of a bisphenol A diglycidyl ether type epoxy (trade name Epicote 828, manufactured by Sikol Co., Ltd.) which is liquid at room temperature and has an epoxy equivalent of 190.
(4 epoxy equivalents) at 180 to 200°C for about 1.5 hours to obtain a solid imide ring-containing epoxy resin with an epoxy equivalent of 1110.

1110 g (1 epoxy equivalent) of the imide ring-containing epoxy resin and 139 g (0.9 g) hexahydrophthalic anhydride.
(acid anhydride equivalent) using a ball mill, and after grinding 35
It was sieved to 0 micron.

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 impact tester (load 501, center of impact 1/4 inch) and the result was 28 cm, and the cross test was also good.

Erichsen test was 4 mm. Further, the weight loss of the cured resin after 500 hours at 200° C. in air was 2.9 times.

[Example 2] 280 g (0.1 acid equivalent) of an imide ring-containing dicarboxylic acid compound represented by the structural formula BTDI-2 and an epoxy equivalent of 23
460 g (2.0 epoxy equivalent) of Novolac type epoxy (trade name: Ciba Araldye I-ECN-1280) of No. An imide ring-containing epoxy resin was obtained.

After mixing and pulverizing 100 g of the imide ring-containing epoxy resin and 7 g of dicyandiamide using a ball mill,
It was sieved to micron size.

Using this powder composition, a coating film was formed on a copper plate having a width of 30 mm, a thickness of 2.5 mm, and a length of 45 cm by electrostatic powder coating.

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 was carried out at 10 KV and no defects were observed in the 5 coatings.

The weight loss of this cured resin after 500 hours at 200° C. in air was about 3.7 times.

[Example 3] 28.0 g (0.1 acid equivalent) of an imide ring-containing dicarboxylic acid compound represented by the structural formula BTDI-3 and an epoxy equivalent,
450 bisphenol A diglycidyl ether type epoxy (trade name Dow Chemical Company DER-661),
450g (mixed with 1 epoxy equivalent, 180-200
The reaction was carried out at a temperature of about 2 hours to obtain a solid imide ring-containing epoxy resin having an epoxy equivalent of 530.

100 g of the imide ring-containing epoxy resin, 6 g of epoxy curing agent BF3-400 (trade name of Harshaw Chemical Co., Ltd.), and 5 g of polyvinyl butyral resin as a flow regulator were mixed and ground using a ball mill, and then sieved to 350 microns to form a powder. A body resin composition was obtained.

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 in normal state is 8.7×1016Ω
cm, and 6.9 x 1015Ω after 24 hours of hot water immersion.
cm, and the breakdown voltage under normal conditions is 19. OKV/0.1m
m, 17.m after 24 hours immersion in hot water. OKV/0. 1
It was mm.

Further, the weight loss of the cured resin obtained in the same manner after 500 hours at 200°C was 4.0%.

Also, add 1 to 5% hydrochloric acid aqueous solution and 5% caustic soda aqueous solution.
Even after immersion for 0 hours, no defects were observed in the coating film.

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

[Example 4] 280 g (1 acid equivalent) of an imide ring-containing dicarboxylic acid compound represented by the structural formula BTDI-3 and 2680 g of bisphenol A diglycidyl ether type epoxy having an epoxy equivalent of 480 (trade name Epicote (001) manufactured by Shell Co., Ltd.)
(5.0 epoxy equivalent) and reacted at 180 to 200°C to obtain a solid imide ring-containing epoxy resin with an epoxy equivalent of 670.

100 g of the imide ring-containing epoxy resin and 8 g of the epoxy curing agent Anchor 1040 (trade name of Anchor Chemical) were mixed and ground using a ball mill, and then sieved to 350 microns.

Next, preheat to 200℃ and make a 20cm x 15cm x
After spraying the above powder composition onto a 0.3 cm copper plate using a spray gun to form a molten continuous coating film on the copper plate, this was heat-treated at 180°C for 30 minutes to obtain a thickness of 2.
A cured resin coating of 0.00 microns was obtained.

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

Moreover, the cross-cathode test was also good.

Further, the weight loss of this cured resin after 500 hours at 200° C. in air was about 1.2%.

Claims (1)

[Claims] (In the formula, R is an aromatic or aliphatic divalent group) A biscarboxylic acid compound having an imide ring and an epoxy compound having at least two epoxy groups in one molecule are combined. The number of epoxy groups in the epoxy compound is 5 to 40 relative to the number of carboxyl groups in the compound.
A solid imide ring-containing epoxy resin (A) and an epoxy curing agent (B) obtained by mixing and reacting in a ratio within the range of
A resin composition for powder coating, characterized by comprising: