JPH0570560A - Resin composition curable with active energy ray - Google Patents

Abstract

PURPOSE:To prepare the title compsn. which is hydrophilic, dilutable with water, and suitable as a coating material excellent in water resistance and adhesion to metal. CONSTITUTION:A compd. having an active hydroxyl group and at least one double bond polymerizable with an active energy ray is reacted with a dicarboxylic acid anhydride to give a half ester, which is reacted with an epoxy resin having at least one glycidyl group on an average in the molecule to give a modified epoxy resin having an acid value of 10 or lower. 100-30wt.% the modified epoxy resin is compounded with 0-70wt.% resin component consisting of a resin having double bonds polymerizable with the active energy ray and/or a resin having no double bond polymerizable wit the active energy ray, thereby giving the title compsn. The modified resin is hydrophilic and curable with the active energy ray, and the compsn. is dilutable with water and used as a coating material excellent in water resistance and adhesion to metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active energy ray-curable resin composition suitable for a coating agent which is hydrophilic, can be diluted with water, and has excellent adhesion to metals and excellent water resistance.

[0002]

2. Description of the Related Art In recent years, curing techniques using active energy rays such as ultraviolet rays and electron beams have a short curing time and good productivity, and generally do not use organic solvents and thus do not worry about air pollution or fire. It is widely recommended because of its superiority, and there are many examples of applications to coated steel sheets. In this case, the resin used is often an epoxy resin because of its adhesiveness to the metal, appropriate hardness, and various resistance.

[0003]

However, as a result of the curing by the active energy ray being completed in a short time of seconds, the stress inside the coating film due to curing shrinkage cannot be relaxed,
Causes poor adhesion. For example, when acrylic acid or methacrylic acid is added to a glycidyl group, which is a commonly used method for imparting active energy ray curability to an epoxy resin, the adhesion to metal of the epoxy resin before addition is high. Is reduced. That is, the result is that the characteristic that the epoxy resin originally has good adhesion to metal is impaired. Also, when coating a metal plate, the viscosity of the coating agent must match the coating machine.
That is, when the viscosity of the coating agent is too high, a method generally used is to dilute using a monofunctional acrylate such as styrene. However, in this case, the monofunctional acrylate has a strong irritation to the skin and has a great influence on the human body. Moreover, when diluted with an organic solvent, one of the advantages of the active energy ray curing technology that there is no danger of fire is lost. In order to solve these problems, an active energy ray curable resin having a molecular skeleton similar to that of an epoxy resin is used in which a double bond is introduced after adding an ether bond to bisphenol. That is, it is a method of adding ethylene oxide to bisphenol. In this case, the resin becomes soft and it is difficult for internal stress to remain, and its ether bond makes it hydrophilic and can be diluted with water. That is, although the above-mentioned problems can be solved, the ether bond introduced here remains in the coating film even after curing, resulting in deterioration of water resistance.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that they are hydrophilic, can be diluted with water, and have excellent adhesion to metals and excellent water resistance. Thus, an active energy ray-curable composition suitable for a coating agent was obtained. That is, the present invention changes to an ether bond in order to impart hydrophilicity, introduces an ester bond by a carboxyl group and a hydroxyl group into an epoxy resin, and at the same time imparts a functional double bond to an active energy ray. It is done in the same way.

A half-esterified product (A) obtained by reacting a dibasic carboxylic acid anhydride with a compound having one active hydroxyl group and one or more radiation-functional unsaturated double bonds in the molecule.
A modified epoxy resin having an acid value of 10 or less obtained by reacting an epoxy resin (B) having an average of 1.0 or more glycidyl groups in the molecule, other resin having an unsaturated double bond functional to radiation, and / or radiation The present invention relates to an active energy ray-curable resin composition in which the weight ratio of the resin having no functional unsaturated double bond is 100/0 to 30/70.

Here, the compound having one active hydroxyl group and one or more radiation-sensitive double bonds is 2
-Hydroxyl ethyl acrylate, 2-hydroxyl propyl acrylate, 2-hydroxyl ethyl methacrylate, monofunctional acrylates such as 2-hydroxyl propyl acrylate, glycerol acrylate,
Bifunctional acrylates such as glycerol methacrylate, and trifunctional acrylates such as pentaerythritol triacrylate can be used. Further, as the dibasic carboxylic acid anhydride, there can be used ordinary dibasic carboxylic acid anhydrides such as phthalic anhydride, hexahydrophthalic anhydride, succinic anhydride, maleic anhydride, polyazelaic anhydride, From the viewpoint of flexibility, an aliphatic acid anhydride having 2 to 20 carbon atoms is more preferable.

As the epoxy resin, a bisphenol type epoxy resin gives good results, and a condensate of bisphenol A, bisphenol F, bisphenol S and epichlorohydrin can be used. Further, a novolac type epoxy resin may be used. However, here, an average of 1.0 glycidyl groups is contained in the epoxy resin molecule.
It is important to have more than one. That is, when the average number of glycidyl groups is 1.0 or less, the amount of double bonds introduced is limited and the curability tends to be poor.

In order to obtain the modified epoxy resin of the present invention by these reactions, a compound having one active hydroxyl group and one or more radiation-sensitive double bonds and a dibasic carboxylic acid are used as the first step reaction. The modified epoxy resin of the present invention may be prepared by preparing a half-esterified product from an anhydride and further adding an epoxy resin in the second step reaction to react the remaining carboxyl group of the half-esterified product with a glycidyl group.

Further, even if the three kinds of raw materials are charged all at once and the modified epoxy resin is prepared in the one-step reaction step, the ester bond is preferentially generated in the reaction rate. It is possible to synthesize modified epoxy resins. Here, the reaction conditions are 50 mol% or more, more preferably 80 mol% of the glycidyl groups in the epoxy resin.
It is important to denature the above, and the acid value at this time is 10
It is necessary to proceed with the reaction until

Therefore, it is necessary to carry out the reaction with a composition that can satisfy this condition, but in order to proceed the reaction to an acid value of 10 or less, an amine-based catalyst is used and a temperature of 80 to 130 ° C. It can be done in time reaction.

When the amount of modification is 50 mol% or less, the absolute amount of double bonds is insufficient and the curability tends to decrease.
In addition, when the acid value is 10 or more, the amount of residual carboxyl groups is large, and this influence reduces the water resistance even in a sufficiently cured coating film.

The epoxy resin of the present invention may contain another resin having an unsaturated double bond.
It is desirable that the radiation-curable resin has an appropriate hydrophilic property if possible, but even a resin having no hydrophilic property can be diluted with water due to the hydrophilic property of the modified epoxy resin of the present invention. .. As other active energy ray curable resin, for example, unsaturated polyester resin, acrylic resin having active energy ray functional double bond, etc. can be used, and Aronix manufactured by Toagosei Co., Ltd. An oligomer having an unsaturated double bond such as Kayarad manufactured by Yakuhin Co., Ltd. may be used.

Further, it is effective for improving the processability of the coating film that the coating film contains a resin which does not have a functional double bond in the active energy ray capable of exerting a plasticizing effect.

For example, urethane resin and polyester resin can be used. However, the range of use is such that the weight ratio of the modified epoxy resin of the present invention to other resins is 100 /
It is 0 to 30/70. If the other resin is used in an amount of more than 70 parts by weight, the adhesion of the epoxy resin of the present invention to the metal becomes difficult to be exhibited, and if a resin having no hydrophilicity is used, it is difficult to dilute with water. Cause

As the base material to which the active energy ray-curable resin composition of the present invention is applied, various coated steel plates, for example, plated steel plates plated with tin, chromium, aluminum, zinc or the like, surface treatment with chromic acid, phosphoric acid, etc. Examples include composite treated steel plates, light metal plates such as aluminum, plastic films, and composite metal materials made by adhering aluminum foil to paper boards.

Further, the active energy ray-curable resin composition of the present invention may contain an alcohol-based or cellosolve-based solvent to the extent that the risk of fire is not remarkably improved to improve coatability. It is possible. For the same reason, a surface tension lowering agent, a defoaming agent, etc. may be added.

Further, it is possible to add an improving additive such as a lubricant, an organic pigment or an inorganic pigment.

Since the coating method has a free viscosity,
It is possible to appropriately select from roll coating, spray coating, dip coating and the like, and it is possible to cure by activating the active energy ray after volatilizing the contained water.

As the active energy ray, a high pressure mercury lamp,
Ultra-high pressure mercury lamps, metal halide lamps, carbon arc lamps, xenon lamps, and other ultraviolet rays, cobalt 60 as a gamma ray, or X-ray generators as x-rays, electron beam accelerators, etc. The electron beam used as the source.

When ultraviolet rays are used as the active energy rays, a polymerization initiator and, if necessary, an accelerator can be used from the viewpoint of curing efficiency.

As the polymerization initiator, benzoin, benzoin methyl ether, methyl o-benzoylbenzoate-p
-Benzoin ethyl ether, benzoin isopropyl ether, benzoins such as α-methylbenzoin,
Acetophenones such as dimethylbenzyl ketal, trichloroacetophenone and 2,2-diethoxyacetophenone 2-hydroxy-2-methylpropiophenone, propiophenones such as 2-hydroxy- ^4' -isopropyl-2-methylpropiophenone , Α-acyloxime ester, benzophenone, methylbenzophenone, p-chlorobenzophenone, p-dimethylaminobenzophenone and other benzophenones, 2-chlorothioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone and other oxanthones, benzyl, dibenzox A polymerization initiator such as beron can be used.

Examples of the accelerator include 4,4 ^'- bis (diethylamino) benzophenone, N- dimethylaminobenzoic acid ethyl, diethanolamine, can be used glycine.

[0023]

EXAMPLES The present invention will be described in more detail below with reference to examples. In addition, the part in an Example shows a weight part.

Synthesis of modified epoxy resin [A] Succinic anhydride 90 parts 2-hydroxyl ethyl acrylate 104 parts Epicoat 828 (manufactured by Shell Chemical Co., Ltd.) 370 parts in a methyl ethyl ketone solvent and the presence of dimethylbenzylamine as a catalyst and hydroquinone 2 at 80 ° C below
After reacting for a time, a half-esterified product is obtained. After further adding and carrying out a reaction at 80 ° C. for 6 hours to give an acid value of 2, methyl ethyl ketone was distilled off from the system. This was diluted with distilled water to obtain a modified epoxy resin [A] of the present invention having a resin content of 80%.

Synthesis of modified epoxy resin [B] Succinic anhydride 90 parts 2-hydroxyl ethyl acrylate 104 parts Epicoat 1001 (manufactured by Shell Chemical Co., Ltd.) 950 parts was dissolved in a butyl acetate solvent, and then,
1 in the presence of dimethylbenzylamine and hydroquinone
The reaction was carried out at 00 ° C for 5 hours to give an acid value of 3, and then butyl acetate was distilled off from the system. This was diluted with distilled water to obtain a modified epoxy resin [B] of the present invention having a resin content of 80%.

Synthesis of modified epoxy resin [C] Phthalic anhydride 104 parts 2-hydroxyl ethyl acrylate 81 parts Epicoat 828 (manufactured by Shell Chemical Co., Ltd.) 370 parts in a methyl ethyl ketone solvent in the presence of dimethylbenzylamine and hydroquinone. React at 80 ° C. for 2 hours to obtain a half-esterified product. After further adding and carrying out a reaction at 80 ° C. for 6 hours to give an acid value of 2, methyl ethyl ketone was distilled off from the system. This was diluted with distilled water to obtain a modified epoxy resin [C] of the present invention having a resin content of 80%.

Synthesis of modified epoxy resin [D] Succinic anhydride 90 parts 2-hydroxyl ethyl acrylate 104 parts Epicoat 828 (manufactured by Shell Chemical Co., Ltd.) and The reaction is carried out at 80 ° C for 2 hours to obtain a half-esterified product. Furthermore, after further adding and carrying out the reaction at 80 ° C. for 3 hours to adjust the acid value to 18, methyl ethyl ketone was distilled off from the system. This was diluted with distilled water to obtain a modified epoxy resin [D] having a resin content of 80%.

Example 1 To 100 parts of the resin content of the modified epoxy resin [A], 1 part of a photoinitiator Darocur 2959 (manufactured by Melook Co.) was added, and then diluted with distilled water to prepare a B type rotational viscometer (6 rp).
The viscosity measured in m) was adjusted to 200 cps. This coating solution was applied on an electrolytic tin-plated plate with a bar coater to a dry film thickness of 3 μm, and after the contained water was volatilized, ultraviolet rays were applied and cured under the condition of 500 mJ / cm ² . The evaluation results are shown in Table 2.

Examples 2-5, Comparative Examples 1-2 After adding 1 part of the photoinitiator Darocur 2959 (manufactured by Melok Co.) to 100 parts of the resin component in the composition shown in Table 1, Example 1 was used. The same operation as in Example 1
5, and the coated plates of Comparative Examples 1 and 2 were prepared. The evaluation results are shown in Table 2.

Example 6 The composition shown in Table 1 was diluted with distilled water to prepare a B type rotational viscometer (6 rp).
The viscosity measured in m) was adjusted to 200 cps. This coating solution was applied to an electrolytic tin-plated plate with a bar coater to give a dry film thickness of 3 μm, and the water content was volatilized.
Irradiation and curing were performed at 0 kGy. The evaluation results are shown in Table 2.

Examples 7 to 10 and Comparative Examples 3 to 4 The compositions shown in Table 1 were diluted with distilled water to prepare a B type rotational viscometer (6 rp).
The viscosity measured in m) was adjusted to 200 cps. Then, the same operation as in Example 6 was performed. The evaluation results are shown in Table 2.

[0032]

[Table 1] 1) Aronix M-1310 (manufactured by Toagosei Co., Ltd.) 2) ADEKA BON TITER HUX-232 (manufactured by Asahi Denka Co., Ltd.)

[0033]

[Table 2]

Evaluation test 1) Peeling test method for cross-cutting; cutting the coating film into 100 cross-cuts of 1.0 mm,
Attach the cellophane tape and peel off the tape to observe the state of peeling of the coating film. Evaluation: No peeling 100 ←-→ 0 Full peeling 2) Impact test method: DuPont impact tester 1/2 inch pin used Evaluation: No change ○, cracks occurred 3) Boiling water test method: Immersion in boiling water 30 minutes evaluation ; No change ○, swelling occurred 4) Rubbing test method; Evaluation of rubbing with a cloth containing methyl ethyl ketone ； No change at 100 times or more ○ Change at 50 to 100 times △ Change at 50 times or less ×

[0035]

INDUSTRIAL APPLICABILITY The present invention relates to an active energy ray-curable resin composition characterized by using an epoxy resin having an active energy ray-curable property and hydrophilicity, which can be diluted with water and can be a metal. It can be used as a coating agent with excellent adhesion to and water resistance.

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Claims (1)

[Claims] 1. A half-esterified product (A) obtained by reacting a dibasic carboxylic acid anhydride with a compound having one active hydroxyl group and one or more unsaturated double bonds functional to the active energy ray in the molecule. A modified epoxy resin having an acid value of 10 or less obtained by reacting an epoxy resin (B) having an average of 1.0 or more glycidyl groups in the molecule, other resins having an unsaturated double bond functional to the active energy ray, and / or An active energy ray-curable resin composition in which the weight ratio of the resin having no functional unsaturated double bond to the active energy ray is 100/0 to 30/70.