JPS583510B2 - 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, polytesterimide resin, polybenzimidazole resin, and polyhydantoin resin are well known as heat-resistant resins. Although it is being commercialized as a resin and a film, it is unsuitable as a powder coating resin due to its high melting point.

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 is based on the general formula (I) (wherein, Ar is an aromatic tetravalent group, R is an aliphatic group,
A dicarboxylic acid compound having two imide groups in one molecule, which is a divalent group representing an aromatic group, and a compound having at least two epoxy groups in one molecule, are combined into an imide ring-containing compound. A solid imide ring-containing epoxy resin (A) and an epoxy curing agent ( The present invention relates to a resin composition for powder coating characterized by comprising B).

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. The imide ring-containing epoxy resin of the present invention can be easily obtained because it is reactive with epoxy resins.

The dicarboxylic acid having an imide group in the side chain used in the present invention has the general formula (where, Ar is an aromatic tetravalent group, and R is a divalent group representing an aliphatic or aromatic group). It is usually produced very easily by the condensation reaction shown in the following formula.

(However, Ar and R are as described above.) The compound of general formula (n) used in the above reaction is shown by, and Z is a carbon-carbon bond, or a compound capable of connecting aromatic groups such as a xylene group. may be any, and A and B are -Mt and -COOH, respectively.
The acid anhydride of the general formula [■] may essentially be any compound that falls under the above definition, but preferably naphtholic anhydride, phthalic anhydride, itaconic anhydride, and succinic anhydride. , chlorentic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc.

The epoxy resin used in the present invention is preferably solid at room temperature, and is a bisphenol-type flocculent obtained by reacting 4,4'-isopropylidene diphenol (bisphenol A) with shrimp chlorohydrin. Epoxy resin is a novolak-type epoxy resin obtained by reacting phenol novolak, cresol novolac, etc. with epichlorohydrin. Commercially available products include Epicote 1001, Epicote 1004, Epicote 1007, and Epicote 1009 as bisphenol-type cotton-like epoxy resins. , Epicote 1
031, (all product names of Shell Chemical Co., Ltd.), DER-6
6 1, DER-542 (all Dow Chemical Company product names), Araldite ECN-1 27 3, ECN as a cresol novolak type epoxy resin
-1 28 0 (both Ciba company product names), Chitsusonox UNOX-207 (Chitsuso UCC product name), Epicron 1000 (Inu Nippon Ink company product name)
These can be pulverized and used individually or as a mixture of two or more.

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 Epico-4828 (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 (1).

Excellent results are obtained when the reactants are 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, 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, and 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 diaminodiphenylnurphone, 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, phorisulfides, 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 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., 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,
It is not preferable to use a coating below 50 microns because dust tends to form 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 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 1 273 g (1 acid equivalent) of an imidodicarboxylic acid compound having the structure 2 PA-DACM and 6801 (2
(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 7,080.

The imide ring-containing epoxy resin 708 (1 (1 epoxy equivalent)) and hexahydrophthalic anhydride 139 g (0
．． 9 acid anhydride equivalents) were mixed in a ball mill, and after pulverizing 350
Sieved to micron size.

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 250 microns. A cured resin coating film was obtained.

This coating film was tested using a DuPont impact tester (load: 500g).
The test result was 28 boxes, and the cross test was also good.

Erichsen test was 6 mm.

Moreover, the weight loss of the cured resin after 500 hours at 200° C. in air was 5.6 times.

Example 2 27.9 g (0.1 acid equivalent) of an imidodihydric sulfonic acid compound represented by the structural formula HA-DACM and an epoxy equivalent of 230
was mixed with 690 g (3.0 epoxy equivalent) of a novolac type epoxy (trade name: Ciba Araldite ECN-1280) and reacted at 180 to 200°C for about 1 hour to form a solid imide ring with an epoxy equivalent of 250. A containing epoxy resin was obtained.

After mixing and pulverizing 100 g of the imide ring-containing epoxy resin and 8 g of dicyandiamide using a ball mill,
It was sieved to 350 microns.

Using this powder composition, a width of 30 mm and a thickness of 2. 5 m
m. A coating film was formed on a copper plate having 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 270 microns thick, smooth and glossy.

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

Moreover, the weight loss of this cured resin after 500 hours at 200° C. in air was about 6.8%.

Example 3 22.4 g (0.1 acid equivalent) of imide ring-containing dicarboxylic acid represented by the structural formula MA-DACM and 450 epoxy equivalents
450 of bisphenol A diglycidyl ether type epoxy (trade name: Dow Chemical Company DER-661)
g (mixed with 1.0 epoxy equivalent, heated at 180-200℃
The mixture was reacted for about 2 hours to obtain a solid imide ring-containing epoxy resin having an epoxy equivalent of 530.

100 g of imide ring-containing epoxy resin and epoxy curing agent Anchor 1040 (Anchor Chemical brand name) 8
g 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 treated at 180°C for 30 minutes to form a cured resin coating film with a thickness of 200 microns. was gotten.

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

Moreover, the cross-cut test was also good.

The weight loss of this cured resin after 500 hours at 200° C. in air was about 9.8%.

Example 4 27.3 g (1 acid equivalent) of imide ring-containing dicarboxylic acid compound having structure 2 PA-DACM and 48 epoxy equivalents
961 of 0 bisphenol A diglycidyl ether type epoxy (trade name: Shell Epicote 1001)
(2 epoxy equivalents) was added, 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 1,440.

100 g of the imide ring-containing epoxy resin and epoxy curing agent BF3-400 (trade name of Harshaw Chemical Company) 8
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 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℃ for 30 minutes to a thickness of 300℃.
A micron cured resin coating was obtained.

The volume resistivity of this coating film under normal conditions is 8.1×1016
Ωcm, and 3.4×1015 after 24 hours of hot water immersion
Ωcm, and the breakdown voltage under normal conditions is 19.1KV/0.
1mm, 16.2KV/0.1 after 24 hours immersion in hot water
It was mm.

Furthermore, the weight loss of the cured resin obtained in the same manner after 500 hours at 200°C was 8.4%.

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 properties such as heat resistance, electrical insulation, mechanical properties, etc. Because of its excellent properties, it is extremely advantageous industrially.

Claims (1)

[Claims] (Here, Ar is an aromatic tetravalent group, R is an aliphatic group,
A dicarboxylic acid compound having two imide groups in one molecule (which is a divalent group representing an aromatic group) and an epoxy compound having at least two epoxy groups in one molecule are combined into an imide ring-containing compound. The number of epoxy groups in the epoxy compound is 2 to 3 relative to the number of carboxyl groups in the compound.
Solid imide ring-containing epoxy Jugetsu WA and epoxy curing agent (B) obtained by mixing and reacting in a ratio in the range of 0
A resin composition for powder coating, characterized by comprising: