JPS583515B2 - 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 applied to the object to be coated by powder coating 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 insulation properties, it is not always satisfactory in terms of heat resistance. It is not something that will be done.

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 research aimed at solving these problems, we have found that conventionally, introduction of heterocycles into epoxy membrane fat has been achieved by 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 relates to general formula (I) (In the formula, the OH substituent indicates the 0-, m-, p-position.

) The number of epoxy groups is 2 to 30 for each hydroxyl group of the diphenol compound having two imide rings in one molecule, and It relates to a powder coating resin composition consisting of an imide ring-containing epoxy resin (A) that is solid at room temperature and a hardened epoxy resin (B) obtained by mixing and reacting the derivatives having an imide ring. is poorly soluble, and conventionally it has been considered difficult to introduce imide rings into epoxy resins. However, the imide ring-containing diphenol compound represented by the above general formula (1) has good compatibility with epoxy resins, and is also difficult to introduce into epoxy resins. The imide ring-containing epoxy resin of the present invention can be easily obtained.

The imide ring-containing diphenol compound represented by the general formula (1) used in the present invention is butane-1,2,3.4
It can be easily synthesized from 1 mole of -tetracarboxylic acid or its mono- or dianhydride and 2 moles of an amine phenol such as 0-aminophenol, m-aminephenol, p-aminephenol.

This reaction can be carried out even in a reaction system in which aminophenol is substantially added in excess, by a method in which the aminophenol is removed as unreacted aminophenol.

That is, specified amounts of the reaction components were m-cresol, N,N-dimethylformamide, N,N-dimethylacetamide N,
- Place in a suitable reaction vessel with an organic solvent such as methylpyrrolidone or tetrahydrofuran, and heat at 80 to 220°C for 30 minutes.
This can be easily achieved by heating for ~10 hours.

The epoxy resin used in the present invention is preferably one that is solid at room temperature, and is a bisphenol-type linear resin obtained by reacting 4,4'-isopropylidene diphenol (bisphenol (A)) with epichlorohydrin. It is a novolak-type epoxy resin obtained by reacting an epoxy resin, phenol novolac, cresol novolak, etc. with shrimp chlorohydrin. 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 Dow Chemical Company product names), and Araldide ECN-1273 and ECN-1280 as cresol novolac type epoxy resins.
(all brand names from Ciba Corporation), and others such as Chissonox UNOX-207 (trade name from Chitsuso UCC) and Epicron 1000 (trade name from Dainippon Ink Co., Ltd.), which are used individually or in combination of two or more for grinding as appropriate. be able to.

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 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 diphenol 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 one hydroxyl group of the imide ring-containing diphenol.

If the number of epoxy groups in the epoxy resin is less than 2 for one hydroxyl group of the imide ring-containing diphenol, the compatibility will be poor and the work will be difficult, and if it is more than 30, the compatibility will improve, but the resulting imide ring-containing Epoxy resins are inappropriate because they do not show much improvement in heat resistance.

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), hexahydrophthalic anhydride (HHPA), acid anhydrides such as phthalic anhydride, amines such as diaminodiphenylmethane and diaminodiphenyl sulfone, Anchor 1040 (trade name of Anchor Chemical Company), BF3-4
BF3-based complexes such as 00 (trade name of Harshaw Chemical Co., Ltd.), carboxylic acids, imidazoles, polyamides, polysulfides, dicyandiamide, etc. can be used alone or in combination as appropriate.

The total 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,
Further, acid anhydrides, amines, and the like are suitably blended in an arbitrary range (an amount corresponding to 80 to 100% of the epoxy equivalent) usually used for the epoxy equivalent of the epoxy resin of the imide ring-containing epoxy resin.

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 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.

Although the curing temperature varies depending on the melting point of the resin component and the type and amount of the catalyst, a temperature of 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 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 diphenol compound represented by the general formula (1) are shown.

Example 1 Imidophenol (molecular weight 380) shown by structure 2 BIP-1 with 191 (1 hydroxyl group equivalent) and epoxy equivalent 48
960 of 0 bisphenol A diglycidyl ether type epoxy (trade name: Shell Epicote 1001)
g (2.0 epoxy equivalent) and heated at 180 to 200°C.
The mixture was reacted for about 1 hour to obtain a solid imide ring-containing epoxy resin having an epoxy equivalent of 1,150.

1150 g (1 epoxy equivalent) of the imide ring-containing epoxy resin and 150 g (0.0 g) hexahydrophthalic anhydride.
9 acid anhydride equivalents) using a ball mill, and after pulverizing 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 impact tester (load: 500 g, center of impact 1/4 inch), and the result was 26 sieves, and the cross test was also good.

Erichsen test was 6 mm.

Further, the weight loss of the cured resin after 500 hours at 200° C. in air was 1.3%.

Example 2 Imidophenol 19.0 with structure 2 BIP-2
g (0.1 hydroxyl equivalent) and epoxy equivalent of 230 novolak type epoxy (trade name Ciba Araldite EC)
N-1280) and 6907 (3.0 epoxy equivalent) were mixed 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 244.

After mixing and pulverizing 100 g of the imide ring-containing epoxy resin and dicyandiamide 7 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 2.5 cm, 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 photosensitive.

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

The weight loss of this cured resin after 500 hours at 200° C. in air was about 7.4%.

Example 3 Imidophenol 38.0 with structure 2 BIP-3
? (0.2 hydroxyl equivalent) and 450 g 1.0 of bisphenol A diglycidyl ether type epoxy (trade name Dow Chemical Company DER-661) with epoxy equivalent weight 450.
(epoxy equivalent) and reacted at 180 to 200°C to obtain a solid imide ring-containing epoxy resin with an epoxy equivalent of 620.

100 g of the imide ring-containing epoxy resin and 8 zo of 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 size 20cm x 15cm x 0
．． 3 (1771) by spraying the above powder composition onto a 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 film with a thickness of 200 microns. A cured resin coating was obtained.

An impact test similar to Example 1 on this coating was carried out at 23c.
m, and Erichsen test was 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 6.7%.

Example 4 190 g of imidophenol represented by structural formula BIP-1
(1 acid equivalent) and bisphenol A with epoxy equivalent of 480
9609 (2,O epoxy equivalent) of diglycidyl ether type epoxy (trade name Epikote 1001 from Shell Co., Ltd.) was mixed and reacted at 180 to 200°C for about 1.5 hours to form a solid imide ring with an epoxy equivalent of 1150. A containing epoxy resin was obtained.

100 g of the imide ring-containing epoxy resin, 6 g of the epoxy curing agent BF3-400 (trade name of Harshaw Chemical Co., Ltd.) and 5 g of the flow control agent 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 O
．． 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 4.7×1016Ω
cm, and 1.9 x 1015Ω after 24 hours of hot water immersion.
cm, and the breakdown voltage under normal conditions is 19.8KV/0.1m.
m, 15.7KV/0.1mm after 24 hours of hot water immersion
Met.

Furthermore, the weight loss of the cured resin obtained in the same manner after 500 hours at 200°C was 1.0%.

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 properties such as heat resistance, electrical insulation, mechanical properties, etc. It is extremely advantageous industrially.

Claims (1)

[Scope of Claims] 1 hydroxyl group of a diphenol compound having two imide rings in one molecule represented by the general formula (in the formula, the OH substituent indicates the O-, m-, p-position) A solid imide ring-containing epoxy resin (A) obtained by blending an epoxy resin having at least two epoxy groups in one molecule at a ratio of 2 to 30 epoxy groups and reacting with the epoxy resin (A) and epoxy curing. A resin composition for powder coating, characterized in that it consists of an agent (B).