JPS583513B2 - 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. Although it is being commercialized, it is unsuitable as a powder coating resin due to its high melting point.

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 imide 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.

That is, the present invention provides general formula (I) (in the formula, the substituents of -OH include p-, m-, p-)
The number of epoxy groups of the epoxy compound is 2.2 to 2.2 to the number of functional groups (carboxyl group and hydroxyl group) of the compound containing an imide ring, and the epoxy resin is a compound containing an imide term in the molecule represented by The present invention relates to a resin composition for powder coating characterized by comprising a solid imide term-containing epoxy resin (5) and an epoxy curing agent (B) obtained by blending in a range of 20 to 20%.

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

The imide ring-containing phenolic carboxylic acid represented by the general formula (1) used in the present invention is prepared by combining 1 mol of trimellitic acid or trimellitic anhydride with the general formula (OH substituents are o-, p-, m 1 mole of the amine phenol (including the - position).

This reaction can essentially be carried out by removing the amine phenol as an unreacted product even when the amine phenol is added in excess.

That is, the specified amounts of reaction components are m-cresol, N,N
- dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, etc. in a suitable reaction vessel, and
The reaction can be easily accomplished by heating at 0°C for 3-10 hours.

The epoxy resin used in the present invention is preferably one that is solid at room temperature, and is a busphenol-type resin obtained by reacting 4,4'-impropylidene diphenol (bisphenol A) with shrimp chlorohydrin. epoxy resin or phenolic novolac,
It is a novolac-type epoxy resin obtained by reacting cresol novolac with epichlorohydrin. Commercially available products include Epicote 1001 and Epicote 10 as bisphenol-type linear epoxy resins.
04, Epicote 1007, Epicote 1009, Epicote 1031 (all trade names of Shell Chemical Co., Ltd.), DE
R-661, DER-542 (both are trade names of Dow Chemical Company), Araldite ECN-1273 and ECN-1280 (both are trade names of Ciba Company) are available as Talesol novolac type epoxy resins, and other Chitsonox U
NOX-207 (Chisso UCC brand name), Epicron 1
000 (trade name of Dainippon Ink Co., Ltd.) and the like, which 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 ring-containing dicarboxylic acid compound represented by the general formula (I).

The number of epoxy groups in the epoxy resin is 2.2 to 20 per carboxyl group of the imide ring-containing dicarboxylic acid.
Excellent results are obtained when using reactants in the range of .

If the number of epoxy groups in the epoxy resin is less than 2.2 for one functional group of the imide ring-containing phenolic carboxylic acid, the compatibility will be poor and the work will be difficult; Although the compatibility is improved, the heat resistance of the resulting 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 dimethylsulfosside, 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, 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, silica, or calcium carbonate may be added during mixing. A filler such as titanium oxide, a colorant, a plasticizer, etc. may be added to the 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 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 general formula (I) are shown.

[Example 1] 141.5 g (1 equivalent) of an imide ring-containing phenol carboxylic acid compound represented by the structural formula PTMP and an epoxy equivalent of 3
6 of 400 bisphenol A diglycidyl ether type epoxy (trade name: Shell Epicote 1009)
800g (2.0 epoxy equivalents) and 1 epoxy equivalents
38 g of 90 bisphenol A diglycidyl ether type epoxy (trade name: Shell Epicote 828)
(0.2 epoxy equivalent) and heated to 180-200℃
The mixture was reacted for about 1 hour to obtain a solid imide ring-containing epoxy resin having an epoxy equivalent of 5,820.

5820 g (1 epoxy equivalent) of the imide ring-containing epoxy resin and 139 g (0.5 g) hexahydrophthalic anhydride.
9 acid anhydride equivalents) were mixed in a ball mill, pulverized, and then sieved to 350 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 using a DuPont impact tester (load: 500g,
The center of impact (1/4 inch) was 25 cm, and the cross test was also good.

Erichsen test was 5 mm.

Further, the weight loss of the cured resin after 500 hours at 200° C. in air was 8.5 times.

[Example 2] 14.19 (0.1 equivalent) of an imide ring-containing phenolic carboxylic acid compound represented by the structural formula MTMP and 460 g of a novolac type epoxy (trade name: Ciba Araldite ECN-1280) with an epoxy equivalent of 230. 2.0 epoxy equivalent) 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 250.

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 width of 30 mm, a thickness of 2.5 mm,
A coating film was formed on a 45 cm long copper plate by electrostatic powder coating.

This was heated at 220° C. for 30 minutes to harden 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.

Moreover, the weight loss of this cured resin after 500 hours at 200° C. in air was about 6.5%.

[Example 3] 14.1 g (0.1 equivalent) of an imide ring-containing phenolic carboxylic acid compound represented by the structural formula OTMP and a bisphenol A diglylly ether type epoxy having an epoxy equivalent of 450 (trade name: Dow Chemical Company DER-661) 451 (1.0 epoxy equivalent) and 180 to 2
The reaction was carried out at 00° C. for about 2 hours to obtain a solid imide ring-containing epoxy resin having an epoxy equivalent of 520.

100 g of imide ring-containing epoxy resin, 6 g of epoxy curing agent BF3-400 (trade name of Harschau Chemical Co., Ltd.)
After mixing and pulverizing 5 g of polyvinyl butyral resin as a flow regulator using a ball mill, the mixture was sieved to 350 microns to obtain a powder resin 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 8.2×1016Ω
・cm, and 1.5 x 1015 after 24 hours of hot water immersion
Ω・cm, and the breakdown voltage under normal conditions is 18. OKV/0.
1mm, after 24 hours immersion in hot water, 15.7KV/0.
It was 1 mm.

In addition, cured resin obtained in the same manner was heated at 200°C and 500°C.
The weight loss after hours was 6.2%.

[Example 4] Imide ring-containing phenolic carboxylic acid represented by the structural formula PTMP 28.29 (0.2 equivalent) and epoxy equivalent 4 8
480 of 0 bisphenol A diglycidyl ether type epoxy (trade name: Shell Epicote 1001)
g (1.0 epoxy equivalent) was added thereto, and the reaction was carried out at 180 to 200°C to obtain a solid imide ring-containing epoxy resin having an epoxy equivalent of 640.

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 2 cm copper plate using a spray gun to form a molten continuous coating film on the copper plate, and then heat treated at 180°C for 30 minutes to form a 2 cm thick copper plate.
A cured resin coating of 0.00 microns was obtained.

An impact test similar to Example 1 on this coating was carried out at 27c.
m, Erichsen test 4 mm.

The cross-cut test was also good. The weight loss of this cured resin after 500 hours at 200°C in air was 4.
It was 0%.

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

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 thereof has excellent heat resistance, electrical insulation, mechanical properties, etc. Therefore, it is extremely advantageous industrially.

Claims (1)

[Claims] 1 A compound containing an imide ring in the molecule represented by the general formula (in the formula, the substituents for -OH include q-, p-, and m-) is a compound containing an imide ring. Solid imide ring-containing epoxy resin and epoxy curing agent (B) obtained by mixing and reacting the epoxy compound in a ratio in which the number of epoxy groups in the epoxy compound is in the range of 2.2 to 20 with respect to the number of functional groups in A resin composition for powder coating, characterized by comprising: