JPS583507B2 - 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 imide ring-containing epoxy resin obtained by reaction has excellent thermal stability. Moreover, despite the introduction of a heterocycle, it is well compatible with or mixed with commonly known curing agents, and a uniform resin composition can be easily obtained, and a resin composed of the imide ring-containing epoxy resin and an epoxy curing agent can be obtained. The present inventors have completed the present invention by discovering that the composition satisfies the above-mentioned drawbacks, can be used in powder form, and can provide a thermosetting film with an insoluble and infusible network structure.

That is, the present invention provides carboxylic acid compounds having two imide rings in one molecule represented by the general formula (I) (wherein R is an aliphatic or aromatic divalent group) and (It) (wherein R is the same as above) At least one carboxylic acid compound having one imide ring in one molecule and an epoxy compound are combined with the number of carboxyl groups of the compound containing an imide ring. A solid imide ring-containing epoxy resin (A) and an epoxy curing agent (8) obtained by blending the epoxy compound with the number of epoxy groups in the range of 5 to 40.
The present invention relates to a resin composition for powder coating, characterized by comprising the following.

Generally, diducts with imide rings are poorly soluble. Conventionally, it has been considered difficult to introduce imide rings into epoxy resins, but the imide ring-containing dicarboxylic acid compounds represented by the above general formulas (I) and (■) have good compatibility with epoxy resins and are compatible with epoxy resins. The imide ring-containing epoxy resin of the present invention can be easily obtained.

The imide ring-containing dicarboxylic acid compound represented by the general formula (I) used in the present invention is composed of 2 moles of trimellitic acid or trimellitic anhydride and a general
It can be easily obtained by heating and reacting H2 (wherein R is the same as above) with 1 mol of a primary diamine.

Further, the imide ring-containing dicarboxylic acid compound represented by the general formula (■) is a monoamino acid compound having 1 mol of trimellitic acid or trimellitic acid anhydride and the general formula N2N-R-COOH (wherein R is the same as above). It can be easily obtained by heating and reacting with 1 mole of carboxylic acid.

That is, a specified amount of the reaction components is placed in an appropriate reaction vessel together with an organic solvent such as cresol, dimethylformamide, dimethylacetamide N-methylpyrrolidone, or tetrahydrofuran, and the reaction is carried out by heating at 80 to 220°C for 3 to 10 hours. can be easily achieved.

The primary diamine represented by the general formula N2N-R-NH2 includes 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, benzidine,
3.3'-dichlorobenzine, 4.4'-diphenyl sulfide, 4.4'-diaminodiphenylsulfone,
3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene metaphenylene diamine, paraphenylene diamine, 3,3'-dimethyl-4,4' diphenyl ether enyldiamine,
Meta-xylylene diamine, para-xylylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, diaminopropane, 1,4-diaminonic hexane, etc., also have the general formula H2N-R-CO
As the monoaminocarboxylic acid represented by OH, β-aminopropionic acid, γ-amino abbreviation, glycine, anthranilic acid, meta-aminobenzoic acid, para-aminobenzoic acid, etc. are used.

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'-impropylidene 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 shrimp chlorohydrin. Commercially available products include Epicote 1001 and Epicote 1004 as bisphenol type linear epoxy resins.
, Epicote 1007, Epicote 1009, Epicote 1031 (all trade names from Shell Chemical Co., Ltd.), DER-
661, DER-542 (all brand names from Dow Chemical Co.), Araldite ECN-1273 and ECN-1280 (all brand names from Ciba Co., Ltd.) as cresol novolac type epoxy resins, and Chitsonox uNO.
X-207 (Chitsuso UCC brand name), Epicron 105
0 (trade name of Dainippon Ink Co., Ltd.), etc., and they can be crushed and used individually or in a mixture of two or more as appropriate.

In addition, as long as the resulting imide ring-containing epoxy resin is solid at room temperature, the Evokiji 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 also possible to use liquid epoxy resin alone, and there is no problem at all.

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 5 to 40 per carboxyl group of the imide ring-containing dicarboxylic acid.

If the number of epoxy groups in the epoxy resin is less than 5 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 40, the compatibility will improve but the resulting 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, in order to start the reaction more easily, it is possible to add a small amount of aliphatic tertiary amine that does not contain active hydrogen, or a small amount of potassium carbonate or sodium carbonate. The addition of catalyst does not reduce the effectiveness of the invention in any way.

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 diaminodiphenyl sulfone, Anchor 1040 (trade name of Anchor Chemical Company) BF3-40
BF3 complexes such as 0 (trade name of Harjau Chemical Company), 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 (N) and the epoxy curing agent (B) are powdered and then mixed into a uniform mixture using a stirrer such as a pole 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 imide ring-containing dicarboxylic acid compound represented by the general formula (1) are shown.

Example 1 273 g (1
(acid equivalent) and 2400 g (5.0 epoxy equivalent) of bisphenol A diglycidyl ether type epoxy (trade name: Shell Epicote 1001) having an epoxy equivalent of 480 were mixed and reacted at 180 to 200°C for about 1 hour to determine the epoxy equivalent. A solid imide ring-containing epoxy resin of 670 was obtained.

670 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 25.
A cured resin coating film of 0 micron was obtained.

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

Erichsen test was 6 mm.

Furthermore, the weight loss of the cured resin after 500 hours at 200° C. in air was 1.8%.

Example 2 27.4 g of imidocarboxylic acid represented by structural formula 1-2 (
0.1 acid equivalent) and a novolak type epoxy with an epoxy equivalent of 230 (trade name Ciba Araldite ECN-12)
80) and 920 g (4 epoxy equivalents) of 18
React at 0 to 200°C for about 1 hour, and the epoxy equivalent is 240.
A solid 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 350 microns.

Using this powder composition, a coating film was formed on a copper plate having a width of 30 mm, a thickness of 25 mm, and a length of 45 cm by 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 6.8%.

Example 3 59.8 g of imidocarboxylic acid represented by structural formula 1-3 (
0.2 acid equivalent), 2720 g (0.8 epoxy equivalent) of bisphenol A diglycidyl ether type epoxy (trade name Shell Co., Ltd. Epicote 1009) with an epoxy equivalent of 3400, and bisphenol A diglycidyl ether type epoxy (trade name: Shell Co., Ltd. Epicote 1009) which is liquid at room temperature. Add 83 g (0.2 epoxy equivalent) of Epicoat 828 (trade name: Cie Co., Ltd.), and add 18
The reaction was carried out at 0 to 200°C to obtain a solid imide ring-containing epoxy resin having an epoxy equivalent of 3520.

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

Next, preheat to 200℃ and size 20cm x 15cm x 0
．． The above powder composition was sprayed onto a 3 cm copper plate using a spray gun to form a molten continuous coating film on the copper plate, which was then heat treated at 180°C for 30 minutes to form a 2 cm thick film.
A cured resin coating of 0.00 microns was obtained.

An impact test similar to Example 1 on this coating was conducted at 25c.
m, Erichsen test 5 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 7.5 times.

Example 4 228 g (1
(acid equivalent) and 4500 g (10 epoxy equivalent) of bisphenol A diglycidyl ether type epoxy (trade name Dow Chemical Company DER-661) having an epoxy equivalent of 450 were mixed and reacted at 180 to 200°C for about 1.5 hours. A solid imide ring-containing epoxy resin having an epoxy equivalent of 530 was obtained.

100 g of the imide ring-containing epoxy resin, 6 g of epoxy curing agent βF3-400 (trade name of Harshaw Chemical Co., Ltd.) and 5 g of flow regulator polyvinyl butyral resin were mixed using a ball mill, pulverized, and then sieved to 350 microns. A powder 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 under normal conditions is 8.9×1016Ω
cm, and 1.9 x 1015 after 24 hours of hot water immersion
Ωcm, and the breakdown voltage under normal conditions is 19.2KV/0.1
mm, 15.9KV/0.1m after 24 hours immersion in hot water
It was m.

In addition, cured resin obtained in the same manner was heated at 200°C and 500°C.
The weight loss after hours was 4.2%.

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 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, and the cured product has excellent heat resistance, electrical insulation, and other properties. Therefore, it is extremely advantageous industrially.

Example 5 232 g (1
2500 g of bisphenol A di(methylglycidyl) ether type epoxy (trade name: Inu Nippon Ink Co., Ltd. Epicron 1050) with an acid equivalent of 500 and an epoxy equivalent of 500 (
5 epoxy equivalents) and 2400 g (5 epoxy equivalents) of epoxy 480 bisphenol A diglycidyl ether type epoxy (trade name: Shell Epicote 1001) and reacted at 180 to 200°C for about 1 hour to reduce the epoxy equivalents. A solid imide ring-containing epoxy resin of No. 570 was obtained.

After mixing and pulverizing 100 g of the imide ring-containing epoxy resin and dicyandiamide 11 using a ball mill,
It was sieved to 350 microns.

Using this powder composition, a coating film was formed on a steel plate with a width of 30 mm, a thickness of 25 mm, and a length of 45 cm by an electrostatic powder coating method.

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

This coating showed good properties in various electrical and mechanical tests.

Example 6 156 g of imidocarboxylic acid represented by structural formula 11-1 (
1 acid equivalent) and 2400 g (5 epoxy equivalents) of bisphenol A diglycidyl ether type epoxy (trade name: Shell Epicote 1001) with an epoxy equivalent weight of 480.
and reacted at 180 to 200°C for about 1 hour to obtain a solid imide ring-containing epoxy resin with an epoxy equivalent of 640.

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 250 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 coating showed good properties in various tests.

Example 7 125 g of imidocarboxylic acid (1
acid equivalent) and epoxy equivalent of 230 (product name: Ciba Araldite ECN-1280)
1150g (5.0 epoxy equivalent) of
React at 0 to 200°C for about 1 hour, and the epoxy equivalent is 320.
A solid imide ring-containing epoxy resin was obtained.

After mixing and pulverizing 100 g of the imide ring-containing epoxy resin and 6 g of dicyamide 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 25 mm, and a length of 45 cm by an electrostatic powder coating method.

This was heated at 200° C. for 30 minutes to harden the coating film.

The coating film formed was approximately 100 microns, smooth and glossy.

The weight loss of this cured resin after 500 hours at 200° C. in air was about 5.6%.

It also showed good electrical and mechanical properties.

Claims (1)

[Scope of Claims] 1. A carboxylic acid compound having two imide rings in one molecule represented by the general formula (I) (wherein R is an aliphatic or aromatic divalent group), and At least one compound of a carboxylic acid compound having one imide ring in one molecule represented by the general formula (■) (wherein R is the same as above) and an epoxy compound are combined to form the carboxyl group of the compound containing an imide ring. Blended in a ratio such that the number of epoxy groups in the epoxy compound is in the range of 5 to 40 with respect to the number of
A resin composition for powder coating comprising a solid imide ring-containing epoxy resin (5) obtained by reaction and an epoxy curing agent (B).