JPH0623232B2 - Method for producing vinyl ester resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a vinyl ester resin. Specifically, in the presence or absence of a liquid polymerizable monomer or solvent and a polymerization inhibitor, an epoxy compound such as an epoxy resin and an unsaturated-basic acid such as acrylic acid or methacrylic acid are mixed with a trace amount of sub-acid. The present invention relates to a method for producing a light-colored vinyl ester resin by reacting with an esterification catalyst in the presence of phosphoric acid or (and) phosphite diester, which is widely used for molding materials, FRP, paints, adhesives and the like. Is what is used. In particular, it is useful for applications such as casting resin and gel coat that require aesthetics and various photocuring applications that require excellent photocurability as a photocurable resin.

[Conventional technology]

Generally, a vinyl ester resin includes an epoxy compound having at least one epoxy group in a molecule, an unsaturated-basic acid such as acrylic acid or methacrylic acid and a tertiary amine,
Secondary amine, the same salt, using an esterification catalyst represented by a quaternary ammonium salt, if necessary, a polymerization inhibitor,
Using a reactive monomer and solvent, in the presence of oxygen at 60 ° to 150 °
It is synthesized without gelation by heating and stirring at ℃ for a certain period of time.

However, in the case of such a synthesis, the hue of the obtained vinyl ester resin shows a Gardner color number of 3 to 8, and while having excellent corrosion resistance, chemical resistance, water resistance, heat resistance and mechanical properties, In reality, the use of gel coats, artificial marbles, etc. with aesthetics is extremely limited because of insufficientness. The reason why the hue is not sufficient overlaps with many factors such as reaction temperature, time, atmosphere, type and amount of esterification catalyst, type and amount of inhibitor, etc., but it depends largely on the atmosphere and catalyst. As an improving means, a tertiary amine, a secondary amine, a salt thereof, an esterification catalyst such as a quaternary ammonium salt, a phosphine compound such as triphenylphosphine,
The additional use of stibine compounds such as triphenylstibine is disclosed, for example, in US Pat. No. 3,312,465.

However, in the case of adding triphenylphosphine, when the acid value becomes low along with the progress of esterification, the desired hue cannot be obtained, and in some cases the hue becomes worse than in the case of no addition, so that a relatively high acid value is obtained. Limited to the production of vinyl ester resins. Further, in the case of triphenylstibine, the progress of the reaction is extremely slow, and depending on the type of epoxy resin, it easily gels, its range of use is narrowed, and it is toxic and difficult to handle.

[Problems to be Solved by the Invention]

In view of the current situation as described above, the present invention aims to provide a method for producing a vinyl ester resin having a low acid value by minimizing the coloring in the production of a conventional vinyl ester resin, and without causing gelation at all. To do.

[Means for Solving the Problems]

As a result of intensive studies to solve the above problems, the present inventors conducted esterification reaction in the presence of a small amount of phosphorous acid and / or phosphite diester, resulting in a higher yield than conventional vinyl ester resins. The present invention has been completed by finding that even a resin with little coloring does not gel even when an inert gas is used instead of air as the atmosphere to obtain a lighter colored resin. The hue of the resulting vinyl ester resin is 50 or less if it is represented by Hazen color number,
It is equivalent to or less than the unsaturated polyester resin and methacrylic resin that have been conventionally used for artificial marble, and its cured product is comparable.

In the method of the present invention, a small amount of phosphorous acid and / or phosphorous acid diester is used in an amount of 0.01 to 1 part by weight, more preferably 0.05, based on 100 parts by weight of the total of the epoxy compound and the unsaturated-basic acid.
~ 0.5 parts by weight is sufficient. If it exceeds this range, the curability is impaired, and if it is less than this range, the lightening effect becomes insufficient.

The epoxy compound used in the present invention is, for example, a compound having at least one epoxy group in its molecule, and is obtained by a condensation reaction of bisphenols such as bisphenol A and bisphenol S with epihalohydrin. Ether type epoxy resin, novolac type glycidyl ether type epoxy resin obtained by condensation reaction of epihalohydrin with novolak, which is a condensation product of phenol, cresol, bisphenol and formalin; tetrahydrophthalic acid, hexahydrophthalic acid, benzoic acid and epihalohydrin, and Glycidyl ester type epoxy resin obtained by condensation reaction of glycidyl ether type epoxy resin obtained by condensation reaction of hydrogenated bisphenol or glycol with epihalohydrin; hydantoin Known publicly-known epoxy resins such as amine-containing glycidyl ether resins obtained by condensation reaction of cyanuric acid and epihalohydrin, and epoxy resins in the molecule by addition reaction of the above-mentioned epoxy resin with polybasic acids or (and) bisphenols. It may be a compound having a group.

As the unsaturated-basic acid used in the present invention, for example, acrylic acid, methacrylic acid, and crotonic acid are generally used, but maleic acid and half-esters of itaconic acid may be used as the same-effect substance.

Some or most of these unsaturated-basic acids are fumaric acid, itaconic acid, unsaturated polycarboxylic acids such as citraconic acid, acetic acid, propionic acid, lauric acid, saturated monovalent carboxylic acids such as palmitic acid, phthalic acid. It is also possible to use saturated polycarboxylic acids or their anhydrides, and optionally saturated or unsaturated alkyds having a terminal carboxyl group.

Phosphorous acid and / or phosphite diester used in the present invention means, in addition to inorganic phosphorous acid, diethylhydrogen phosphite, dipropylhydrogenene phosphite, diisopropylhydrogenene phosphite, dibutylhydrogenenephosphite. Fight, diallyl hydrogen phosphite, dicyclohexyl hydrogen phosphite, dibenzyl hydrogen phosphite,
Examples thereof include dioctyl hydrogen phosphite and diphenyl hydrogen phosphite, which are not particularly limited.

Examples of the esterification catalyst include tertiary amines such as trimethylbenzylamine and tributylamine, quaternary ammonium chlorides such as trimethylbenzylammonium chloride, inorganic salts such as lithium chloride and chromium chloride, and 2-ethyl-4-methyl. An imidazole compound such as imidazole, tetrabutylurea, triphenylphosphine, tritolylphosphine, triphenylstibine, etc. alone or in combination may be a publicly known catalyst, but preferably tetramethylphosphonium chloride, diethylphenylpropyl. Phosphonium chloride, triethylphenylphosphonium chloride, benzyltriphenylphosphonium chloride,
Phosphonium salts such as dibenzylethylmethylphosphonium chloride and benzylmethyldiphenylphosphonium chloride are more preferable because of their reactivity and stability of hue over time.

As the inhibitor, hydroquinone, methylhydroquinone, methoxyhydroquinone, tert-butylhydroquinone, benzoquinone, catechol, copper naphthenate,
A publicly known one such as copper powder is used.

The most commonly used polymerizable monomer is a styrene monomer, but other than this, divinylbenzene, chlorostyrene, (meth) acrylic acid ester, diallyl phthalate, vinyl acetate are used depending on the intended use and application. ,
Trimethylolpropane triacrylate or the like can be used. This polymerizable monomer may be used as a solvent in the case of the reaction, and is also used as a solvent for a high-viscosity vinyl ester resin to adjust the viscosity.

In the present invention, it goes without saying that the reaction can be produced even in an atmosphere of an inert gas such as nitrogen gas, carbon dioxide or helium, and can be produced in the presence of oxygen, for example, in an air atmosphere. From the viewpoint of preventing coloring, it is more desirable to carry out the reaction in an inert gas atmosphere.

〔Example〕

Hereinafter, the method of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 In a four-necked flask equipped with a stirrer, a cooling tube, a gas introduction tube and a thermometer, 378 g of a bisphenol type epoxy resin having an epoxy equivalent of 189 (AER-331L manufactured by Asahi Kasei Co., Ltd.), 172 g of methacrylic acid and benzyltriphenyl. Phosphonium chloride 1.65 g, hydroquinone 0.2 g, phosphorous acid 0.8 g,
Add 0.5 g of dibutylhydrogen phosphite, and let nitrogen gas flow into the reaction system at 150 ml / min for 2 hours at 125 ° C.
After reacting for 30 minutes, a vinyl ester resin having an acid value of 12.5 mg KOH / g was obtained. Styrene monomer added to the resulting vinyl ester resin
214 g was added to obtain a vinyl ester resin (A).

Example 2 In a 5 four-necked flask equipped with a stirrer, a cooling tube, a gas introduction tube and a thermometer, a diglycidyl ester resin having an epoxy equivalent of 160 (Epomic R-54 manufactured by Mitsui Petrochemical Co., Ltd.) was used.
0) 2400g, methacrylic acid 1290g, benzyltriphenylphosphonium chloride 11.1g, hydroquinone 1.35
g, phosphorous acid 5.1 g, dibutyl hydrogen diene phosphite 1.8 g, react with nitrogen gas at 450 ml / min for 90 minutes at 125 ° C. while reacting with nitrogen gas, vinyl ester resin with acid value 7.2 mg KOH / g Got 952 g of styrene monomer was added to the obtained vinyl ester resin to obtain vinyl ester resin (B).

Example 3 A one-necked four-necked flask equipped with a stirrer, a cooling pipe, a gas introduction pipe and a thermometer was charged with a bisphenol type epoxy resin having an epoxy equivalent of 257 (manufactured by Shell Petrochemical Industry Co., Ltd., * Picoat 83
4) 494g, methacrylic acid 172g, benzyltriphenylphosphonium chloride 2.0g, hydroquinone 0.23g,
Add 1 g of phosphorous acid and 100 g of hydroxypropyl acrylate, and while flowing nitrogen gas at 150 ml / min into the reaction system, 125
The reaction was carried out at 0 ° C for 4 hours to obtain a vinyl ester resin having an acid value of 15.5 mgKOH / g. To the obtained vinyl ester resin, 308 g of styrene monomer was added to obtain a vinyl ester resin (C).

Example 4 In a 2 four-necked flask equipped with a stirrer, a cooling tube, a gas introduction tube and a thermometer, 378 g of a bisphenol type epoxy resin having an epoxy equivalent of 189 (AER-331L manufactured by Asahi Kasei Co., Ltd.), 172 g of methacrylic acid, benzyltriphenyl. Phosphonium chloride 0.88g, dibutyl hydrogen phosphite
Add 0.66g and 0.17g of hydroquinone and add air to the reaction system.
Acid value 8.0mgK by reacting at 125 ℃ for 6 hours while flowing at 0ml / min
OH / g vinyl ester resin was obtained. 174 g of styrene monomer was added to the obtained vinyl ester resin to obtain a vinyl ester resin (D).

Example 5 A two-four-necked flask equipped with a stirrer, a cooling tube, a gas introduction tube, and a thermometer was placed in a bisphenol epoxy resin having an epoxy equivalent of 257 (Shell Petrochemical Industry Co., Epicoat 83).
4) 900 g, 265 g of methacrylic acid, 69 g of 3,6-endomethylenetetrahydrophthalic anhydride (brand name hymic acid anhydride), 0.37 g of benzyltriphenylphosphonium chloride, 0.37 g of hydroquinone, 1.6 g of butyrohydrodienephosphite Put 350 ml / min of air into the reaction system.
Acid value 12.6mgKOH / g
Of vinyl ester resin was obtained. Styrene monomer 665g was added to the obtained vinyl ester resin.
(E) was obtained.

Comparative Example 1 In a four-necked flask equipped with a stirrer, a cooling tube, a gas introduction tube and a thermometer, 378 g of a bisphenol type epoxy resin having an epoxy equivalent of 189 (AER-331L, manufactured by Asahi Kasei Co., Ltd.), 172 g of methacrylic acid, benzyltriphenyl. Phosphonium chloride (1.65 g) and hydroquinone (0.2 g) were added, and the reaction was carried out at 125 ° C. while flowing nitrogen gas at 150 ml / min into the reaction system, but after 65 minutes gelling had occurred.

Comparative Example 2 In a four-necked flask equipped with a stirrer, a cooling tube, a gas introduction tube and a thermometer, 378 g of a bisphenol type epoxy resin having an epoxy equivalent of 189 (AER-331L manufactured by Asahi Kasei Co., Ltd.), 172 g of methacrylic acid and benzyltriphenyl. Phosphonium chloride (1.65 g) and hydroquinone (0.2 g) were added, and the reaction was carried out at 125 ° C. for 2 hours and 30 minutes while flowing air at 150 ml / min to obtain a vinyl ester resin having an acid value of 10.2 mg KOH / g. 214 g of styrene monomer was added to the obtained vinyl ester resin to obtain a vinyl ester resin (F).

Test Results Table 1 shows the properties of the vinyl ester resins (A) to (F) obtained in Examples 1 to 6 and Comparative Example 2.

[Effect of the Invention] It is necessary to have an aesthetic appearance such as a gel coat or a colorless, light-colored paint or an artificial marble using a white filler such as aluminum hydroxide, which is conventionally colored and has excellent properties as a resin. The vinyl ester resin, which has been considered to be a problem as a raw material in the field, is greatly improved in the degree of coloring by the method of the present invention, and can be used for applications where aesthetics and color tone are a problem without impairing the function of the resin. In addition to being able to do so, it is possible to perform thick photocuring because of its excellent transparency, and it has become possible to expand the application as a photocurable resin.

Claims (1)

[Claims] 1. A process for producing a vinyl ester resin by reacting an epoxy compound with an unsaturated basic acid, which comprises reacting with an esterification catalyst in the presence of phosphorous acid and / or phosphorous acid diester. And a method for producing a vinyl ester resin.