JP2003268072A - Active energy ray-curable epoxy resin-based solid composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid photo-cation-polymerizable epoxy resin which has excellent photocurability with active energy ray, gives the cured product having good physical properties, and has excellent storage stability. <P>SOLUTION: This solid epoxy resin having a softening point of 80 to 150°C and a number-average mol.wt. of 1,000 to 10,000 is obtained by reacting a hydrogenated bisphenol type epoxy compound represented by general formula 1 with a bisphenlo-based compound represented by general formula 2. An active energy ray-curable epoxy resin-based solid composition comprises the solid epoxy resin and a cationic polymerization initiator. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solid epoxy resin composition which is cured by irradiation with active energy rays such as ultraviolet rays. More specifically, photocurability, storage stability, adhesion, chemical resistance, etc. obtained by blending a photocationic polymerization initiator with a solid epoxy resin obtained by reacting a hydrogenated bisphenol type epoxy compound with a bisphenol compound. The present invention relates to a photocationically polymerizable epoxy resin-based solid composition which can be used for applications such as excellent powder coatings, coating agents, adhesives, sealants, molding materials, and film / sheet materials.

[0002]

2. Description of the Related Art Generally, epoxy resins have excellent characteristics such as adhesiveness, mechanical properties, heat resistance, chemical resistance, and electrical properties, and are used as adhesives, paints, civil engineering and construction materials, electric / electronic component materials, and insulating materials. Widely used in. It is also known as a photocationically polymerizable compound that cures with active energy rays such as ultraviolet rays and electron rays. Examples of the cationic photopolymerizable compound include a glycidyl ether type epoxy resin having a glycidyl group as an epoxy resin, an alicyclic epoxy resin, a vinyl ether compound, and an oxetane compound. Among them, alicyclic epoxies and glycidyl ether type epoxy resins are often used in actual use. Glycidyl ether epoxy resins are rich in types, but tend to have poor curability unless they are polyfunctional. there were.

In this tendency, a hydrogenated bisphenol A type epoxy resin has recently been attracting attention as an epoxy resin which is bifunctional and excellent in photocurability, adhesiveness and weather resistance. This resin is bisphenol A
Since it has a structure that does not contain an aromatic ring unlike type epoxy resin and bisphenol F type epoxy resin, it hardly absorbs light in the ultraviolet region and does not hinder the curing of the resin due to the light absorption and decomposition of the photopolymerization initiator. It is characterized in that the phenomenon of yellowing (the appearance of general-purpose bisphenol A type epoxy resin is colored yellow) hardly occurs when it is continuously exposed to light. In addition, unlike the alicyclic epoxy resin that is actually used, it has the characteristics of good water resistance and solvent resistance when photocured, and also has a low curing shrinkage ratio, so a good coating film can be obtained. . Therefore, among the cationically polymerizable cured resins, there are great expectations as a material that has both practically usable performance and cost.

Conventionally, as a general method for producing a glycidyl ether compound having a cyclohexane ring such as this hydrogenated bisphenol A type epoxy resin, a method of glycidyl etherifying a hydroxyl group of an alcohol compound having a cyclohexane ring with epichlorohydrin is used. Is synthesized by. However, the compound obtained by such a conventional production method is mainly composed of a compound in which a hydroxyl group is simply glycidyl etherified, and the content of an oligomer or a polymer component produced by the reaction of an epoxy group once produced again. There were few.

Therefore, the product obtained by this method is in a liquid form, and cannot be basically used for applications such as powder coatings in which a solid substance is used in the form of powder, and a solid bisphenol A type epoxy resin. Even if it is blended with, etc., it cannot be used because it has a low softening point and causes blocking during storage. Further, when the cured product requires heat resistance, a cured product having a higher glass transition temperature is more likely to be obtained when the resin composition before curing has a higher molecular weight. However, there is a problem that the glass transition temperature after curing is low and the desired heat resistance cannot be obtained.

On the other hand, solid bisphenol A type epoxy resins and bisphenol F type epoxy resins can solve the problem of storage stability, but are inferior in photocurability because of the large proportion of aromatic rings in the molecule. There was a flaw.

In addition to the above-mentioned general method for producing a glycidyl ether compound having a cyclohexane ring, a special and expensive catalyst prepared by dissolving an aromatic epoxy resin in an organic solvent and supporting rhodium or ruthenium on graphite is used. A glycidyl ether compound having a cyclohexane ring can also be obtained by a method of selectively hydrogenating an aromatic ring in the presence. According to this method, although a solid product containing an oligomer or a polymer component can be obtained by hydrogenating an aromatic epoxy resin having a high molecular weight, it is a process that is not easy to manufacture and is costly.

From these circumstances, the photocurability and photocurable physical properties of hydrogenated bisphenol A type epoxy resin are utilized,
There has been a demand for a solid cationic photopolymerizable epoxy resin which can be easily produced and has excellent storage stability.

[0009]

DISCLOSURE OF THE INVENTION As a result of intensive studies conducted by the present inventors to solve the above-mentioned problems, the general formula 1 obtained by the conventional glycidyl etherification method was used.

[Chemical 1] (R is a hydrogen atom or a C1-5 alkyl group, a and b are natural numbers of 1 to 4, Y is an alkylene group of 1 to 10, an alkylidene group or a direct bond, m is 0 to 2, G1 and G.
2 represents a hydrogen atom or a glycidyl group. However, G1,
G2 is not a hydrogen atom) and a hydrogenated bisphenol type epoxy compound represented by the general formula 2

[Chemical 2] (R is a hydrogen atom or a C1-5 alkyl group or a halogen atom, c and d are natural numbers of 1 to 4, Z is an alkylene group of 1 to 10, an alkylidene group or a direct bond). The solid epoxy resin composition obtained by mixing a solid epoxy resin having a softening point of 80 ° C. to 150 ° C. and a number average molecular weight of 1,000 to 10,000 and a cationic polymerization initiator is photocurable. It was also found that it has excellent storage stability.

That is, the present invention relates to hydrogenated bisphenol A.
Bisphenol A to liquid hydrogenated bisphenol type epoxy compound having cyclohexane ring such as epoxy resin
By mixing a cationic polymerization initiator into a solid epoxy resin obtained by reacting a bisphenol compound such as, and curing with an active energy ray, a cured product or coating film having excellent adhesion, chemical resistance, etc. can be obtained. Provided is a photocationically polymerizable epoxy resin-based solid composition excellent in photocurability and storage stability.

[0011]

Detailed Structure and Function of the Invention The synthetic method of the solid epoxy resin used in the composition of the present invention will be described in more detail. First, as a first step, a hydroxyl group of an alcohol compound having a cyclohexane ring is converted to a glycidyl group by a generally known method. Etherification gives an epoxy compound. This epoxy compound can be obtained by reacting a hydrogenated bisphenol type compound with epichlorohydrin. At this time, an addition reaction is carried out using a catalyst such as an amine or a Lewis acid in an inert solvent such as toluene or xylene, and then a ring closure reaction is carried out using an alkali such as NaOH.
It can also be synthesized by using a one-step reaction method or a method of directly reacting in one step using an alkali in an epichlorohydrin solvent.

Next, the hydrogenated bisphenol type epoxy compound obtained as a result of the above reaction is reacted with a bisphenol compound. This is a continuous reaction between an epoxy group of a hydrogenated bisphenol type epoxy compound and a hydroxyl group of a bisphenol type compound, and after charging both at a ratio to obtain a target molecular weight, they are mixed and melted under a solvent-free condition. By using an amine-based catalyst such as triethylamine, a quaternary ammonium salt catalyst such as tetramethylammonium chloride, or a phosphorus-based catalyst such as triphenylphosphine or tetrabutylphosphonium bromide until the hydroxyl groups of the bisphenol compound are almost eliminated. The desired solid epoxy resin is obtained.

Examples of the hydrogenated bisphenol type epoxy compound having a cyclohexane ring in the present invention include hydrogenated bisphenol A / diglycidyl ether, hydrogenated bisphenol F / diglycidyl ether, hydrogenated bisphenol AD / diglycidyl ether and hydrogenated phenol. Novolak polyglycidyl ether, hydrogenated cresol novolac polyglycidyl ether, hydrogenated naphthalenediol diglycidyl ether, hydrogenated resorcin diglycidyl ether, hydrogenated biphenol diglycidyl ether, hydrogenated tetramethyl biphenol diglycidyl ether, Examples thereof include hydrogenated trisphenol methane / polyglycidyl ether. The hydroxyl groups of the original alcohol compound may not be completely glycidyl etherified.

The number average molecular weight and the softening point of the solid epoxy resin in the present invention are determined by the proportion of the hydrogenated bisphenol type epoxy compound and the bisphenol compound, the kind of the compound, the kind and the addition of the catalyst so that the desired performance can be obtained. The number average molecular weight of the product is preferably 1000 to 10000, more preferably 1200 to 6000, though it can be adjusted optionally depending on the amount, reaction conditions and the like. The softening point is preferably 80 to 150 ° C., more preferably 90 to
It is 120 ° C. If the number average molecular weight is 1000 or less or the softening point is 80 ° C. or less, the amount of oligomers formed is small, so that the storage stability is poor and the heat resistance of the photocured product cannot be increased, and the number average molecular weight is 10,000 or more. If the softening point is 150 ° C. or higher, a high polymer is excessively formed, which makes it difficult to handle in actual use and the appearance after photocuring becomes poor.

The cationic photopolymerization initiator used in the present invention may be an ionic photogenerating type or a nonionic photogenerating type as long as it is a compound that initiates cationic polymerization of an epoxy group by irradiation of ultraviolet rays. May be

Examples of the ionic photoacid generating type photocationic polymerization initiator include aromatic iodonium salts,
Examples thereof include onium salts such as aromatic sulfonium salts and aromatic diazonium salts, and organic metal complexes such as iron-arene complexes, and one or more of these may be used.

Specific examples of the above-mentioned cationic photopolymerization initiator of the ionic photoacid generating type are not particularly limited, but for example, aromatic sulfonium salts include bis [4].
-(Diphenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate, bis [4- (diphenylsulfonio) phenyl] sulfide bistetrafluoroborate, Bis [4- (diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate, diphenyl-4
-(Phenylthio) phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio)
Phenylsulfonium tetrafluoroborate, diphenyl-4- (phenylthio) phenylsulfonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate,
Triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4 −
(Di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluoroantimonate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfidebistetra Fluoroborate, bis [4- (di (4-
(2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, etc .; aromatic iodonium salts include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, Diphenyliodonium tetrakis (pentafluorophenyl)
Borate, bis (dodecylphenyl) iodonium hexafluorophosphate, bis (dodecylphenyl)
Iodonium hexafluoroantimonate, bis (dodecylphenyl) iodonium tetrafluoroborate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexafluorophosphate, 4-methylphenyl-
4- (1-methylethyl) phenyliodonium hexafluoroantimonate, 4-methylphenyl-4-
(1-Methylethyl) phenyliodonium tetrafluoroborate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrakis (pentafluorophenyl) borate, etc .; aromatic diazonium salts include phenyldiazonium hexafluorophosphate, Phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, phenyldiazonium tetrakis (pentafluorophenyl) borate, and the like, and one or two of these
There are more than one species. When two or more kinds of photocationic polymerization initiators are used in combination, two or more kinds of photocationic polymerization initiators having different effective active wavelengths may be used for multistage curing.

The amount of the above-mentioned photo-cationic polymerization initiator to be added to 100 parts by weight of the solid epoxy resin produced by the present invention is not particularly limited, but is preferably 0.1 to 10 parts by weight, particularly 1 to 5 parts by weight. Parts are preferred. When the amount is 0.1 part by weight or less, the amount of acid generated by the initiator upon irradiation with energy rays is too small to obtain a sufficient cured product, and 1
If it exceeds 0 parts by weight, the amount of acid generated from the initiator increases, and the amount of impurities remaining in the cured product finally increases too much, which adversely affects the periphery of the cured product such as corrosion.

Although the hydrogenated bisphenol type epoxy compound produced by the present invention is essential for the above-mentioned curable composition, the curable composition is not limited to the use as a single substance, but the original properties of the resin composition of the present invention. Other types of glycidyl ether type epoxy compounds, alicyclic epoxy compounds, oxetane compounds and the like may be mixed within the range that does not impair the above.

The resin composition of the present invention is activated by irradiating it with an active energy ray to generate a photocationic polymerization initiation substance, and the polymerization is initiated with a relatively low energy to cure. The active energy rays are not particularly limited, but include, for example, microwaves, infrared rays, visible light, ultraviolet rays, X-rays, γ rays, electron beams, and the like, preferably, among them, simple and economical ultraviolet rays. used.

The above-mentioned ultraviolet light source is not particularly limited, and examples thereof include a mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp and a metal halide lamp, and a mercury lamp and a high-pressure mercury lamp are preferable. used.

The details of the present invention will be specifically described below with reference to synthesis examples and examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[0023]

[Synthesis Example 1] 125 g of hydrogenated bisphenol A, 375 g of toluene, and 2 g of tin tetrachloride were placed in a 1 L four-necked flask equipped with a stirrer, a thermometer, a condenser, and a dropping funnel.
Then, 102 g of epichlorohydrin was added dropwise at 60 ° C., and the mixture was further stirred for 30 minutes. Then, at the same temperature, 20
% NaOH 240g was added and it was made to react for 2 hours. The aqueous layer was separated, and the oil layer was added again with 120 g of 20% NaOH.
Was added and reacted at 60 ° C. for 2 hours. After this, the aqueous layer was separated again, washed with 100 g of distilled water and separated, and then the toluene of the oil layer was distilled off to obtain a viscous liquid hydrogenated bisphenol A type epoxy compound. Then, a stirrer,
A 1 L separable flask equipped with a thermometer was charged with 185 g of the product synthesized above and 75 g of bisphenol A, 0.5 g of tetramethylammonium chloride was added, and the mixture was reacted at 150 ° C. for 12 hours. After completion of the reaction, the product was taken out, cooled and pulverized to obtain a slightly yellow solid having an epoxy equivalent of 1400 and a softening point of 98 ° C. This product had a number average molecular weight of 2,500 as determined by GPC analysis. The color number with a 50% anisole solution was Gardner 1 or less.

[0024]

[Synthesis Example 2] 185 g of the hydrogenated bisphenol A type epoxy compound obtained in Synthesis Example 1 and 84 g of bisphenol A
Charged with tetramethylammonium chloride 0.5
After adding g, the mixture was reacted at 150 ° C. for 15 hours under a nitrogen stream. After completion of the reaction, the product was cooled and pulverized to obtain a slightly yellow solid having an epoxy equivalent of 2350 and a softening point of 119 ° C. This product has a number average molecular weight of 4300 and 50% according to GPC analysis.
The number of colors in the anisole solution was Gardner 1 or less.

[0025]

[Synthesis Example 3] Bisphenol A to bisphenol F66
The reaction was performed under the same conditions as in Synthesis Example 1 except that the amount was changed to g to obtain a slightly yellow solid having an epoxy equivalent of 1350 and a softening point of 91 ° C. This product has a number average molecular weight of 25 by GPC analysis.
The number of colors in the 00, 50% anisole solution was Gardner 1 or less.

[0026]

[Synthesis Example 4] The reaction was performed under the same conditions as in Synthesis Example 2 except that 161 g of tetrabromobisphenol A was used instead of bisphenol A, and the epoxy equivalent was 1450 and the softening point was 115.
A slightly yellow solid at 0 ° C. was obtained. According to GPC analysis, this product had a number average molecular weight of 2,800 and the color number in a 50% anisole solution was Gardner 1.

[0027]

[Comparative Synthesis Example 1] The reaction was carried out under the same conditions as in Synthesis Example 2 except that the amount of bisphenol A was changed to 41 g to obtain a slightly yellow solid having an epoxy equivalent of 455 and a softening point of 70 ° C. According to GPC, this product had a number average molecular weight of 850 and a color number in a 50% anisole solution was Gardner 1 or less.

[0028]

[Comparative Synthesis Example 2] The reaction was carried out under the same conditions as in Synthesis Example 2 except that the amounts of bisphenol A and tetramethylammonium chloride were changed to 93 g and 1.5 g, respectively, and the epoxy equivalent was 7,000 and the softening point was 155 ° C. A yellow solid was obtained.
According to GPC analysis, this product has a number average molecular weight of 12,000,
The number of colors in the 50% anisole solution was Gardner 1 or less.

[0029]

COMPARATIVE SYNTHESIS EXAMPLE 3 Under the same conditions as in Synthesis Example 1, except that the hydrogenated bisphenol A type epoxy compound synthesized in Synthesis Example 1 was changed to 157 g of bisphenol A diglycidyl ether (Epicoat 828 manufactured by Japan Epoxy Resin Co., Ltd.). The reaction is carried out to obtain an epoxy equivalent of 1320 and a softening point of 109.
A slightly yellow solid at 0 ° C. was obtained. According to GPC analysis, this product had a number average molecular weight of 2500 and the color number in a 50% anisole solution was Gardner 1 or less.

The measured values of the solid epoxy resin compounds obtained in Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 to 3 are summarized in Table 1.

[0031]

[Table 1]

[0032]

Examples 1 to 5 100 parts by weight of the solid epoxy resins obtained in Synthesis Examples 1 to 4 were mixed with triallylsulfonium hexafluorophosphate salt as a photocationic polymerization initiator (manufactured by Union Carbide Japan Co., Ltd. UVI-6
990 ") or bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluoroantimonate (Asahi Denka Co., Ltd.
(Adeka Optomer SP-170, manufactured by Co., Ltd.) was added and mixed, and then melt-mixed using a biaxial kneader. The obtained kneaded product is cooled and solidified, and then crushed to 150
It was filtered through a mesh sieve to obtain an epoxy resin-based solid composition. The storage stability of the obtained composition was evaluated. The results are shown in Table 1.

Further, this composition was applied as a pretreatment to a steel plate washed with acetone so that the film thickness was about 30 μm, and was heated and melted at 150 ° C. for 5 minutes in a dryer to form a coating film. (With cold mirror, lamp output 80
(W / cm) and irradiated with ultraviolet rays to cure. The coating film performance of the test piece thus obtained was measured. The results are shown in Table 2.

The evaluation method is as follows. In addition, the coating film appearance, adhesion, and solvent resistance were evaluated by using ultraviolet light of 800 mJ /
The coating film irradiated with cm ² was evaluated. Photocurability: The coating film irradiated with ultraviolet rays was rubbed 5 times with absorbent cotton impregnated with methyl ethyl ketone, and the minimum ultraviolet irradiation amount (mJ / cm ² ) that did not swell or dissolve was measured. ○, 200 for irradiation dose of 200 mJ / cm ² or less
~400mJ / cm ² of things △, was evaluated as × 400 mJ / cm ² or more things. Storage stability: The obtained powder was placed in a 50 ml aluminum cup (upper diameter 58 mm, lower diameter 42 mm) so that the height was 1 cm, and allowed to stand at 30 ° C. for 7 days, and then the state was observed. . A good product without any lumps was evaluated as ◯, a product that was slightly lumped but was loosened when pressed with a finger was evaluated as Δ, and a product that was lumped and was not loosened even with a finger was evaluated as ×. Appearance of coating film ... The appearance of the finish of the coating film was observed. A product having gloss and excellent smoothness was evaluated as ◯, a product having slightly poor gloss and smoothness was evaluated as Δ, and a product having poor gloss and smoothness was evaluated as x. Adhesion ... Evaluated according to JIS K5400 cross-cut tape method in which twice the minimum ultraviolet irradiation amount was irradiated. Solvent resistance: After rubbing the coating film 5 times with absorbent cotton impregnated with each solvent (ethanol, methyl ethyl ketone),
The state of the coating film was visually observed. When the coating film did not change, it was evaluated as ◯, when the gloss was decreased, it was evaluated as Δ, and when peeled or dissolved, it was evaluated as x.

[0035]

[Comparative Examples 1 to 3] The solid epoxy resin compounds obtained in Comparative Synthesis Examples 1 to 3 were cured in the same manner as in Examples 1 to 3, and then evaluated in the same manner. The results are shown in Table 2.

[0036]

[Table 2]

[0037]

The solid photocationically polymerizable epoxy resin according to the present invention is excellent in storage stability and photocurability with active energy rays, and the cured product thereof has good adhesion and chemical resistance. Shows good performance. Utilizing this feature, it can be applied to a wide range of fields such as powder coatings, coating agents, adhesives, sealants, molding materials, and film / sheet materials.

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Claims (2)

[Claims] 1. A general formula 1 (R is a hydrogen atom or a C1-5 alkyl group or a halogen atom, a and b are natural numbers of 1 to 4, Y is an alkylene group of 1 to 10, an alkylidene group or a direct bond, m
Is 0 to 2, G1 and G2 each represent a hydrogen atom or a glycidyl group. However, both G1 and G2 are not hydrogen atoms) and a hydrogenated bisphenol type epoxy compound represented by the general formula 2 (R is a hydrogen atom or a C1-5 alkyl group or a halogen atom, c and d are natural numbers of 1 to 4, Z is an alkylene group of 1 to 10, an alkylidene group or a direct bond). A solid epoxy resin having a softening point of 80 ° C. to 150 ° C. and a number average molecular weight of 1,000 to 10,000. 2. A cationic polymerization initiator of 0.1 to 10 relative to 100 parts by weight of the solid epoxy resin described in claim 1.
An active energy ray-curable epoxy resin-based solid composition containing parts by weight.