JPH0569854B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a photocurable resin composition useful in various fields such as paints, adhesives, and coating agents, and in particular, the present invention relates to a photocurable resin composition useful in various fields such as paints, adhesives, and coating agents. Provides usage instructions. [Prior Art] It is known that an epoxy-crotonate resin obtained by reacting an epoxy resin with crotonic acid is used in combination with a polymerizable monomer such as styrene for curing. Attempts have also been made to cure epoxy-crotonate resins by electron beam irradiation. Furthermore, a reaction product of crotyl alcohol and diisocyanate and a polythiol compound are used together,
Attempts to photocure are also seen here and there, such as in the US patents of WR Grace. However, the first method has the disadvantage that the unsaturated bonds of the crotonate group have very poor reactivity, hardly react with styrene, and have extremely poor curing properties. Furthermore, it is known that when epoxy-crotonate resins are cured by electron beam irradiation, they are not substantially cured at a dose of 10 megarads or less, which is normally used for resins having unsaturated bonds. Furthermore, in the last method, crotyl alcohol is expensive and cannot be said to be an industrially usable raw material. Furthermore, since it has urethane bonds, it has poor heat resistance, and has the disadvantage of lacking heat resistance when immersed in a solder bath at 260°C. [Problems to be Solved by the Invention] The present inventors have solved the low reactivity of the unsaturated bonds of crotonic acid, and have created a photocurable resin that has sufficient heat resistance for practical use at a practical cost. As a result of intensive research to develop the product, we found that by using epoxy-crotonate resin in combination with polyhydric alcohol crotonate and polythiol compounds, it can withstand long-term storage and can be photo-cured with excellent adhesive properties. After learning that it was possible to obtain a unique resin composition, he filed a patent application. The present invention relates to an improvement on the invention of this application, and its purpose is to further speed up the curing rate and increase the hardness. In other words, using polyhydric alcohol crotonate alone may not necessarily have sufficient photocurability, and the hardness of the coating film may be lower than 2H.
If the following is acceptable, it is a waste of time, but it is not necessarily sufficient when higher hardness is desired. [Means for Solving the Problems] The photocurable resin composition of the present invention has the following features: (1) An epoxy resin having two or more epoxy groups in one molecule and crotonic acid are combined into an epoxy group and a carboxyl group. (2) crotonate of polyhydric alcohol; (3) acrylate or methacrylate of polyhydric alcohol (hereinafter referred to as (meth)acrylate of polyhydric alcohol) ), (4) a polythiol compound having two or more thiol groups in one molecule, and (5) a photoreaction initiator. [Function] The feature of the present invention is that crotonic acid is naturally not a curable resin, but it is made curable by reacting with an epoxy resin, and crotonate, a polyhydric alcohol, is combined with (meth)acrylate, a polyhydric alcohol. In addition, a polythiol compound is also used to make it photocurable. By configuring the photocurable resin composition of the present invention as described above, the low reactivity of the unsaturated bond of crotonic acid greatly contributes to the stability of the combined system. Epoxy-crotonate resin and polyhydric alcohol crotonate alone may have slow curing properties, but by combining them with polyhydric alcohol (meth)acrylate and also using a polythiol compound, a practical curing speed can be achieved. is achieved. On the other hand, from the perspective of (meth)acrylate of polyhydric alcohol, it is known that it can be photocured by using it together with a polythiol compound, but in this case, the pot life after mixing the two is extremely short. , it gels within a few hours after mixing, making it impractical. However, another feature of the present invention is that it has been found that this drawback can be overcome by using the polyhydric alcohol crotonate in combination. That is, in the combination system of the above-mentioned epoxy-crotonate resin and polythiol compound, the viscosity tends to be too high for practical purposes, and the viscosity has been controlled by using a solvent or a monomer in combination. When a solvent is used in combination, it may be undesirable from the standpoint of environmental hygiene and disaster prevention. In addition, the combined use of monomers tends to improve the physical properties of the cured product,
However, commonly used monomers such as allyl ether and allyl ester (meth)acrylate react quickly, so they may be used immediately after preparation, but they have the disadvantage that they cannot withstand long-term storage. It was hot. The physical properties of the composition of the present invention can be changed by changing the type and composition of the epoxy resin, polyhydric alcohol, and polythiol compound used, or the ratio of crotonate and (meth)acrylate of the polyhydric alcohol. This makes it possible to respond to diversification of uses. As the epoxy resin used to produce the epoxy-crotonate resin of the present invention, commercially available epoxy resins having two or more epoxy groups in one molecule are used. Typical examples thereof include the following types. (1) Diglycidyl ether type epoxy resin of bisphenol A or bisphenol F is the most typical epoxy resin, and types with different molecular weights are commercially available from various manufacturers. For example, Epicoat from Yuka Ciel Epoxy Co., Ltd.
807, 827, 828, 834, 1001, 1004, 1007,
1010, Ciba Araldite GY-250, GY-
252, GY−255, GY−257, GY−260, GY−
280, Dow Chemical Company's DER−330, 331,
332, 333, 337, 383, 361, 661, Epicron 840, 850, 855, 810 of Dainippon Ink Chemical Industry Co., Ltd.
805, 800, 1050, Epototo YD of Toto Kasei Co., Ltd.
−115, YD−115CA, YD−117, YD−121,
YD−127, YD−128, YD−128S, YD−011,
Mitsui Petrochemical Epoxy Co., Ltd.'s Epomitsuk R-120,
R-128, R-130, R-133, R-139, R-
140, R-301, R-302, etc. (2) Dow Chemical Company's DEN is a pyriglycidyl ether type epoxy resin for Novolak.
-431, 438, 439, ECN-1299 from Ciba, N-740, N-565, N- from Dainippon Ink Chemical Co., Ltd.
Examples include 588. In addition, there are several types of so-called special epoxy resins, and the typical types are shown below. (3) Cycloaliphatic epoxy resin ERL-4221 from Union Carbide Co., Celoxide 3001 from Daicel Corporation, etc. (4) Halogen-containing epoxy resins DER-500 series from Dai Chemical Co., Ltd., Dainippon Ink Chemical Co., Ltd. (5) Polyvalent carboxylic acid glycidyl ester, Epiclon 200, 400, etc. from Dainippon Ink Chemical Co., Ltd. (6) Polyol polyglycidyl ether, Dainippon Ink Chemical Co., Ltd. Epicron 700 series, (7) Others Bisphenol S glycidyl ether, isocyanurate glycidyl ether, etc. The above epoxy resins can also be used together. Although the reaction ratio of epoxy groups and crotonic acid is preferably substantially 1:1, the presence of some residual epoxy groups does not impede the present invention. The reaction between the epoxy resin and crotonic acid is carried out at a temperature of 110 to 150° C. using a reaction catalyst such as a quaternary ammonium salt, tertiary amines, triphenylphosphine, etc. in an amount of about 0.1 to 1 (%). The use of a polymerization inhibitor is not always necessary, and it is also possible to carry out the reaction in an inert gas stream. The polyhydric alcohol crotonate used in the present invention is a product obtained by esterifying the hydroxyl group of a polyhydric alcohol with crotonic acid, and is not particularly limited. The same applies to (meth)acrylates of polyhydric alcohols, but acrylates are more desirable in terms of photocurability. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, glycerin, trimethylolethane, pentaerythritol, dipentaerythritol, hydrogenated bisphenol A, 1,4-cyclohexanedi methanol,
Examples include alkylene oxide adducts of bisphenol A. The mixing ratio of the epoxy-crotonate resin and the total amount of polyhydric alcohol crotonate and (meth)acrylate varies depending on the required viscosity, but the ratio of the epoxy-crotonate resin is
The amount is 10 to 90% by weight, preferably 30 to 70% by weight, and the remainder is the total amount of the polyhydric alcohols crotonate and (meth)acrylate. There is no particular restriction on the mixing ratio of polyhydric alcohol crotonate and polyhydric alcohol (meth)acrylate; Alcohol (meth)acrylate 80~
20% by weight is desirable. It is also possible to use a mixture of crotonic acid and (meth)acrylic acid to esterify a polyhydric alcohol, but no particular advantage has been found, and from the viewpoint of convenience of use, it is preferable to use each ester. It is better to use a mixture. Polythiol compounds to be combined in the mixture of epoxy-crotonate resin and polyhydric alcohol crotonate and (meth)acrylate include, but are not limited to, commercially available esterification products of polyhydric alcohols and thiocarboxylic acids. can be given. For example, trimethylolpropane trithioglycolate, trimethylolpropane trithiopropionate, pentaerythritotetrathioglycolate, pentaerythritotetrathiopropionate, 1,6-hexanedioldithiopropionate, bisphenol A ~ Monoepoxy compound adducts such as dithiopropionate and the like. The ratio of unsaturated bonds to thiol groups in the polyhydric alcohols crotonate and (meth)acrylate is preferably substantially 1:1 in terms of equivalents, but the molar ratio of thiols may be slightly larger and is not strict. Good too. Commercially available photoinitiators can be used as they are.
For example, benzoin alkyl ethers (isopropyl, butyl, isobutyl, etc.), combination systems of benzophenone and amines, acetophenone derivatives, such as benzyl dimethyl ketal (Ciba,
"Irugakiure 651"), hydroxycyclohexyl phenyl ketone ("Irugakiure 184"), hydroxydimethylacetophenone (Merck & Co. "Darukiure #1173"), and the like. It goes without saying that the composition according to the present invention can be used in combination with fillers, reinforcing materials, colorants, polymers, etc. as necessary. [Example] Next, in order to help the understanding of the present invention, examples are shown below. Example 1 Synthesis of epoxy-crotonate (A) 1 equipped with a stirrer, reflux condenser and thermometer
In a separable flask, 360 g of Dow Chemical's DER-332 as an epoxy resin, 172 g of crotonic acid, and 3 g of trimethylbenzylammonium chloride were added and reacted at 120 to 130°C for 4 hours. The acid value was 4.1, so hydroquinone 0.05
g to obtain epoxy-crotonate resin (A) with a Hazen color number of 250 and a viscous syrup form at room temperature. Synthesis of photocurable resin Add 50g of epoxy-crotonate resin (A), 30g of trimethylolpropane tricrotonate, 20g of trimethylolpropane triacrylate, 55g of pentaerythritate tetrathioglycolate, and 2g of benzophenone as a photoinitiator, and uniformly was mixed to obtain a photocurable resin (a). Separately, 50 g of epoxy-crotonate resin (A), 50 g of trimethylolpropane tricrotonate, 55 g of pentaerythritate tetrathioglycolate,
2 g of benzophenone was added as a photoinitiator to prepare a photocurable resin (b). Furthermore, 50 g of epoxy-crotonate resin (A), 50 g of trimethylolpropane triacrylate, 55 g of pentaerythritate tetrathioglycolate, and 2 g of benzophenone as a photoinitiator were added to obtain a photocurable resin (c). Coat the photocurable resins (a) to (c) on a 35μ thick copper foil with a bar coater to a thickness of 30μ,
10cm below the lamp of a UV lamp with an output of 2kW
was repeatedly passed twice at a speed of 2 m/min. The physical properties of the resulting coating film were as shown in Table 1.

[Table] Heat
However, resin (c) containing only trimethylolpropane triacrylate gelled the day after blending. Resin (a) containing a mixture of monomers did not gel even after one month at 25°C. Example 2 Synthesis of epoxy-crotonate resin (B) 1 equipped with a stirrer, reflux condenser, and thermometer
Dow Chemical Company's DEN-438 was used as a novolac type epoxy resin in a separable flask.
360 g, 172 g of crotonic acid, and 2 g of triphenylphosphine were charged and reacted at 130-135°C for 4 hours. The acid value was 11.4, so 0.1 g of hydroquinone was added.
In addition, epoxy-crotonate resin (B) was obtained as a yellowish brown resin that was almost semi-solid at room temperature. Production of photocurable resin 50 g of epoxy-crotonate resin (B), dipentaerythritohexacrylate (manufactured by Nippon Kayaku Co., Ltd., viscosity 29 poise), trimethylolpropane tricrotonate, pentaerythritate tetrathiopropionate , Merck &Co.'s Darokyur #1173 and methyl ethyl ketone were uniformly mixed as a photoinitiator in the proportions shown in Table 2, and photocurable resins (d) to
(h) was obtained. The photocurable resin was coated onto a 35μ thick copper foil to a thickness of 30μ using a bar coater, and after volatilizing the solvent, it was passed once through a 10cm distance under an ultraviolet irradiation device with an output of 2kW at a speed of 2m/min. The properties of the obtained coating film and formulation are summarized in Table 2. From Table 2, the photocurable resins [e] to [f], which are mixtures of acrylate and crotonate, exhibited well-balanced properties in terms of curability and physical properties of the coating film.

[Table] [Effects of the Invention] The photocurable resin composition of the present invention utilizes the properties of crotonic acid groups and (meth)acrylate groups to withstand long-term storage and has the advantage of sufficient curability. It has excellent heat resistance and adhesive properties, and forms a tough film, making it extremely useful for applications such as paints, adhesives, and coding agents. Another object of the present invention is to provide a method for effectively utilizing crotonic acid.

Claims (1)

[Scope of Claims] 1 (1) Obtained by reacting an epoxy resin having two or more epoxy groups in one molecule with crotonic acid in a proportion where the epoxy groups and carboxyl groups are substantially equivalent. Epoxy-crotonate resin, (2) polyhydric alcohol crotonate, (3) polyhydric alcohol acrylate or methacrylate, (4) polythiol compound having two or more thiol groups in one molecule, and (5) photoreaction initiator. A photocurable resin composition consisting of: