JPS6239608B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photocurable epoxy resin composition that can be easily cured by irradiation with light and can form a coating film with excellent adhesion to substrates, particularly metals. In recent years, light curing methods are capable of curing in a shorter time than conventional heat curing methods, and their development has been strongly desired from the standpoint of resource and energy conservation. Conventionally known photocurable resin compositions include resins with α and β-unsaturated double bonds, such as unsaturated polyester resins and reaction products of epoxy resins and acrylic acid (or methacrylic acid). These are rapidly cured when a radical sensitizer such as benzoin alkyl ether is added and irradiated with light. However, these have poor adhesion to base materials such as metals, and are insufficient for coating these materials. As a result of various studies, the present inventors found that before photo-curing the epoxy resin, an epoxy resin having two or more epoxy groups in one molecule and HOOC-CnH ₂ n-
A reaction product obtained by reacting a saturated dibasic acid represented by COOH (n is an integer of 2 to 20) preferably at an equivalent ratio of epoxy group/carboxyl group, etc. of 1.1 to 2.0, an epoxy-based reaction dilution It has been found that when a specific amount of an aromatic onium salt shown below is used, the adhesiveness of the cured product to a substrate such as a metal is improved. The present invention uses an epoxy resin having two or more epoxy groups in one molecule and HOOC-CnH ₂ n-COOH (n
is an integer from 2 to 20) and the epoxy reaction diluent,
The present invention relates to a photocurable epoxy resin composition containing 0.5 to 10% by weight of a photosensitive aromatic onium salt of a group element or a group a element. [(R)a(R ¹ )b(R ² )cX] _d ⁺ [MQe] ^-(ef) (1) In the formula, R is a monovalent aromatic organic group, R ¹ is alkyl, cycloalkyl, and substituted alkyl ^R2 is a heterocyclic group selected from aliphatic groups and aromatic groups or a polyvalent organic group constituting a condensed ring structure; X is a monovalent organic aliphatic group selected from sulfur, selenium, and tellurium; A group a element selected from nitrogen, phosphorus, arsenic, antimony and bismuth
group element, M is a metal or metalloid, and Q is a halogen atom. Also, a is an integer from 0 to 4, b is an integer from 0 to 2, and c
is an integer from 0 to 2, and a+b+c is equal to the valence of X (3 when X is a group a element,
In the case of a group element, 4), d is an integer equal to e−f, f is equal to the valence of M (an integer from 2 to 7), and e is an integer greater than f and up to 8. One of the reasons why the above-mentioned reaction product in the present invention improves adhesion is thought to be because pendant hydroxyl groups are generated as shown below.
A schematic diagram is shown below. The epoxy resin used in the present invention may be any epoxy resin having two or more epoxy groups in one molecule, such as bisphenol A type epoxy resin,
Novolak type epoxy resins are preferred, and these may be used alone or in mixtures. Bisphenol A type epoxy resins include Epicote 828, 834, 836, 1001, 1004, 1007 (trade name manufactured by Ciel Chemical), DER331, 661, 664, 667.
(product name manufactured by Dow Chemical), Araldite 260,
Examples include 280, 6071, 6084, 6097 (product name manufactured by Ciba Geigy). Examples of novolak type epoxy resins include Epicote 152, 154 (trade name manufactured by Ciel Chemical Co., Ltd.), Araldite EPN1138, 1139, Araldite ECN1235,
1273, 1280, 1299 (product name manufactured by Ciba Geigy),
Examples include DEN431 and 438 (product name manufactured by Dow Chemical). Other hydrogenated bisphenol A type epoxy resins can also be used. The above saturated dibasic acids include adipic acid, sebacic acid, succinic acid, decamethylene dicarboxylic acid,
Examples include 1-butylhexamethylene dicarboxylic acid, octadecamethylene dicarboxylic acid, 6-ethylhexadecamethylene dicarboxylic acid, and 6-ethyldodecamethylene dicarboxylic acid, and these may be used alone or in mixtures. The above-mentioned epoxy resin and saturated dibasic acid are preferably reacted at an epoxy group/carboxyl group equivalent ratio of 1.1 to 2.0 in order to obtain a compound having an epoxy group at the end. If the equivalence ratio is less than 1.1, unreacted carboxyl groups tend to remain, resulting in poor product stability; if it exceeds 2.0, theoretically, epoxy resin remains that does not react with the saturated dibasic acid. . Metal halides such as zinc chloride and lithium chloride, dimethyl sulfide,
Sulfides such as methyl phenyl sulfide, sulfoxides such as dimethyl sulfoxide and methyl ethyl sulfoxide, tertiary amines such as N-N dimethylaniline, pyridine, triethylamine, benzyldimethylamine, and their hydrochlorides or bromates, tetramethyl Quaternary ammonium salts such as ammonium chloride and trimethyldodecylbenzyl ammonium chloride, sulfonic acids such as para-toluenesulfonic acid, and mercaptans such as ethyl mercaptan and propyl mercaptan are used. This reaction is possible without a catalyst, but since the reaction is slow, it is preferable to use the above catalyst in an amount of 0.0001 to 1% by weight.
It is added in an amount of 0.001 to 0.5% by weight and heated to 120 to 180°C, preferably 130 to 160°C, for reaction. The acid value of the product is 10 or more and preferably 5 or less. Oxidation
If it exceeds 10, the stability of the product will deteriorate. Since this reaction product is generally solid at room temperature or liquid with high viscosity, it is adjusted to a suitable viscosity for work using an epoxy reaction diluent.
For this purpose, a low viscosity mono- to tri-functional epoxy reactive diluent is used. Examples of the monofunctional epoxy reaction diluent include butyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, 2-ethylhexyl glycidyl ether, and the like. Examples of difunctional epoxy reaction diluents include diglycidyl ethers such as butanediol diglycidyl ether, hexanediol diglycidyl ether, neopentyl glycidyl ether, and other cycloaliphatic group epoxy resins that have low viscosity and can be used as diluents. Examples include Chitsonox 221 and Chitsonox 206 (trade name manufactured by Chitso). Examples of the trifunctional epoxy reaction diluent include trimethylolpropane triglycidyl ether and glycerin triglycidyl ether. The epoxy reaction diluents listed above may be used singly or in combination in commonly used amounts, depending on the application and properties, and there are no particular limitations. As a photosensitizer for epoxy resins
Photosensitive aromatic onium salts of group a elements shown in Japanese Patent Publication No. 14278, photosensitive aromatic onium salts of group a elements shown in Japanese Patent Publication No. 52-14279, and the like can be used. A coating film is created by mixing the above-mentioned onium salts and the like with an epoxy resin, and when this is irradiated with light, the onium salt releases Lewis acid, which hardens the epoxy resin. The Group A element and the photosensitive aromatic onium salt of the Group A element that can be used in the present invention are compounds represented by the above formula (1). The onium salt of group a element included in the above formula (1) is, for example, Examples of onium salts of group a elements represented by formula (1) include the following. The amount of photosensitive aromatic onium salt added is as follows:
The amount is 0.5 to 10% by weight, preferably 1 to 5% by weight, based on the above reaction product and the epoxy reaction diluent used if necessary. If it is less than 0.5% by weight, the curing speed due to light irradiation will be slow;
If it exceeds 100%, it tends to become difficult to form a film. Also,
Depending on the compatibility between the onium salt and the epoxy resin, the onium salt can be dissolved or dispersed in an organic solvent such as nitromethane, acetonitrile, or propylene carbonate. When curing the photocurable epoxy resin composition of the present invention, ultraviolet rays are most efficient and easy to operate. Light sources for this purpose include low-pressure mercury lamps, high-pressure mercury lamps, xenon lamps, carbon arc lamps, and the like. In addition, curing by irradiation with electron beams is also included. The photocurable epoxy resin composition of the present invention is
Bisphenol A type epoxy resin, novolak type epoxy resin, etc. may be added. This photocurable epoxy resin composition also contains inorganic fillers, dyes, pigments, spreading agents, viscosity modifiers,
It may also contain processing aids, ultraviolet screeners, and the like. Further, a wetting agent can be added in an amount of 5% by weight or less based on the photocurable epoxy resin composition so as to prevent repellents and pinholes from forming in the coating film. As a wetting agent, fluorocarbon-based FC-430,
FC-171 (product name manufactured by Sumitomo 3M), silicon-based
SR-82 (Product name manufactured by General Electric Company)
etc. can be mentioned. Examples of the present invention will be described. Parts are by weight. Example 1 Epoxy resin trade name Epicote 828 (epoxy equivalent: 192) 768 parts manufactured by Shell Chemical Co., Ltd., manufactured by Okamura Oil Co., Ltd. 1
-Butylhexamethylene dicarboxylic acid Product name SB
230 parts of -12 (molecular weight 230) and 0.0998 parts of tetramethylammonium chloride were placed in a three-necked flask equipped with a stirrer, stirred while blowing nitrogen gas, and reacted at 145°C for 6 hours to produce a reaction product with an acid value of 0.5. I got it. 50 parts of this reaction product was added to 1.6 hexanediol diglycidyl ether (trade name ED503 manufactured by Asahi Denka).
The mixture was diluted to 50 parts, and a solution of 3 parts of triphenylsulfonium tetrafluoroborate dissolved in 3 parts of acetonitrile was added to prepare a resin composition. This is processed into zinc phosphate treated steel sheets, stainless steel sheets,
Coat the copper plate with a bar coater #28 (cured coating thickness 50μ) and use a 2KW high-pressure mercury lamp (product name manufactured by Toshiba Electric Materials Co., Ltd.).
H2000L/4), irradiation was performed for 30 seconds at an irradiation distance of 15 cm, and the curing characteristics were measured. The results are shown in Table 1. Example 2 50 parts of the reaction product of Example 1 was diluted with 50 parts of neopentyl glycol diglycidyl ether (trade name: Epolite 1500NP manufactured by Kyoeisha Yushi Co., Ltd.), and 3 parts of triphenylsulfonium hexafluoroantimonate were mixed with 3 parts of propylene carbonate. A resin composition was prepared by adding the dissolved material to the solution. This was applied in the same manner as in Example 1, irradiated with light, and the curing characteristics were measured. The results are shown in Table 1. Example 3 80 parts of the reaction product of Example 1 was added to 20 parts of phenyl glycidyl ether (trade name Epiol P manufactured by NOF Co., Ltd.).
A resin composition was prepared by adding 3 parts of triphenylsulfonium tetrafluoroborate dissolved in 3 parts of acetonitrile. This was applied in the same manner as in Example 1, irradiated with light, and the curing characteristics were measured. The results are shown in Table 1. Example 4 Epoxy resin product name manufactured by Dow Chemical, USA
DEN431 (epoxy equivalent 176) 704 parts, manufactured by Okamura Oil Co., Ltd.
230 parts of SB-12 (molecular weight 230) and 0.0934 parts of tetramethylammonium chloride were placed in a three-neck flask equipped with a stirrer, stirred while blowing nitrogen gas, and reacted at 120°C for 18 hours, resulting in a reaction product with an acid value of 4.5. I got something. 60 parts of this reaction product was diluted with 40 parts of ED503, and a solution of 3 parts of triphenylsulfonium tetrafluoroborate dissolved in 3 parts of acetonitrile was added thereto to prepare a resin composition. This was applied in the same manner as in Example 1, irradiated with light,
The curing properties were measured. The results are shown in Table 1. Comparative Example 1 A resin composition was prepared by diluting 50 parts of epoxy resin Epicoat 828 (trade name, manufactured by Shell Chemical, USA) with 50 parts of ED503, and adding thereto a solution of 3 parts of triphenylsulfonium tetrafluoroborate dissolved in 3 parts of acetonitrile. Tsukutsuta. This was applied in the same manner as in Example 1, irradiated with light, and the curing characteristics were measured. Comparative example 2 Epoxy resin product name manufactured by Dow Chemical in the United States
A resin composition was prepared by diluting 50 parts of DEN431 with 50 parts of Epolite 1500NP and adding 3 parts of triphenylsulfonium hexafluoroantimonate dissolved in 3 parts of propylene carbonate. This was applied in the same manner as in Example 1, irradiated with light, and the curing characteristics were measured. The results are shown in Table 1.

[Table] Conventional photocurable resins, such as unsaturated polyester resins, reaction products of epoxy resins, and acrylic acid (or methacrylic acid), have insufficient adhesion to base materials such as metals and have limited applications. Ta. According to the photocurable epoxy resin composition of the present invention, a cured product with improved adhesion to a base material such as metal can be obtained. Examples of applications in which the photocurable epoxy resin composition of the present invention is used include protective, decorative and insulating coatings, printing inks, sealants, adhesives, photolugists, wire insulation, fabric coatings, laminates, Impregnated tapes, printing plates, etc.

Claims (1)

[Claims] 1. An epoxy resin having two or more epoxy groups in one molecule and HOOC-CnH ₂ n-COOH (n is 2 to 20
(which is an integer of aromatic onium salts
A photocurable epoxy resin composition containing 0.5 to 10% by weight. [(R)a(R ¹ )b(R ² )cX] _d ⁺ [MQe] ^-(ef) (1) In the formula, R is a monovalent aromatic organic group, R ¹ is alkyl, cycloalkyl, and substituted alkyl ^R2 is a heterocyclic group selected from aliphatic groups and aromatic groups or a polyvalent organic group constituting a condensed ring structure; X is a monovalent organic aliphatic group selected from sulfur, selenium, and tellurium; A group a element selected from nitrogen, phosphorus, arsenic, antimony and bismuth
group element, M is a metal or metalloid, and Q is a halogen atom. Also, a is an integer from 0 to 4, b is an integer from 0 to 2, and c
is an integer from 0 to 2, and a+b+c is equal to the valence of X (3 when X is a group a element,
In the case of a group element, 4), d is an integer equal to e−f, f is equal to the valence of M (an integer from 2 to 7), and e is an integer greater than f and up to 8.