JPH02296879A - Photocurable adhesive composition - Google Patents

Abstract

PURPOSE:To improve the curing properties, workability, adhesive strength, and water resistance by compounding an epoxy compd., a urethane (meth) acrylate, a specific reactive diluent, a long-chain alkyl (meth)acrylate, and a photopolymn. initiator. CONSTITUTION:20-50wt.% epoxy compd. (A) contg. at least one double bond in the molecule (e.g. an epoxy acrylate obtd. from a bisphenol A epoxy resin and acrylic acid), 10-30wt.% urethane (meth)acrylate (B), and 20-40wt.% reactive diluent (C) which is liq. at room temp. and has at least one double bond in the molecule (e.g. tetrahydrofurfuryl acrylate) are compounded. The resulting compd. is then compounded with 5-30wt.% (based on the sum of A, B, C, and D) long-chain alkyl (meth)acrylate (D) of the formula (wherein R1 is 8-18C alkyl; and R2 is H or CH3) (e.g. lauryl acrylate) and 0.1-10 pts.wt. (based on 100 pts.wt. the sum of A, B, C, and D) photopolymn. initiator (E) (e.g. benzil dimethyl ketal).

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a photocurable adhesive composition that has low hygroscopicity and low water absorption, and has excellent water resistance and adhesive strength. Suitable for use in fixing and adhesion.

[Problems to be solved by conventional techniques and inventions] Conventionally,
Various compositions have been developed as photocurable adhesives and two-component adhesives based on a base agent/curing agent, depending on the intended use.

In the case of photocurable adhesives, it is known that one way to improve adhesive strength is to use monomers such as (meth)acrylates and radically polymerizable carboxylic acid compounds having hydroxyl groups (for example, in 59-41
Publication No. 373, etc.).

However, although adhesives using these seven adhesives exhibit high adhesive strength, they have the drawback of extremely poor water resistance.

In addition, in the case of two-component adhesives, some types of adhesives are known to have excellent adhesive strength and water resistance, but because they are two-component adhesives, they are inferior in workability, and furthermore, adhesives that occur when mixing the base agent and curing agent are known. It often cures while containing air bubbles, which causes a decrease in adhesive strength and poor reliability.

[Means to solve the problem]

Therefore, the present invention has been made in order to solve the above-mentioned problems, and has excellent curing properties by light such as ultraviolet rays, improves workability, and provides reliable adhesives with excellent adhesive strength and water resistance. Provides a highly photocurable adhesive composition.

That is, the present invention provides (al) an epoxy compound having one or more unsaturated double bonds in one molecule, (bl urethane (meth)acrylate, (c) the above (a)
A compound that is liquid at room temperature and has one or more unsaturated double bonds, which acts as a reactive diluent for components (1) and (b), (dl) is a long-chain alkyl (methacrylate, CI) represented by the following general formula. CC00R1 (R+ is an alkyl group having an integer of 8 to 18 carbon atoms,
R2 is a hydrogen atom or a methyl group. ), and (el
A photocurable adhesive composition containing a photopolymerizable initiator.

In this specification, (meth)acrylate refers to acrylate and/or methacrylate, and (meth)acrylic acid refers to acrylic acid and/or methacrylic acid.
A (meth)acryloyl group means an acryloyl group and/or a methacryloyl group, respectively.

The epoxy compound used in the present invention (having one or more unsaturated double bonds in one molecule as an Al component) is an epoxy resin containing (meth)acrylic acid or (meth)acrylate having a carboxyl group in the molecule. It has one or more (usually up to five) (meth)acryloyl groups in the molecule obtained by addition reaction of It gives particularly good results in terms of properties such as less deterioration of physical properties such as adhesive strength.

The epoxy resin used to obtain such an epoxy compound is not particularly limited as long as it has an average of 1.5 or more epoxy groups, preferably an average of 2 or more epoxy groups in one molecule. Moreover, both liquid and solid forms can be used at room temperature.

As specific examples of such epoxy resins, bisphenol type, novolak type, alicyclic type, triglycidyl isocyanurate type and the like epoxy resins can be used alone or in combination of two or more types.

In addition, (urethane (meth)acrylate as a bl component has a urethane bond in the molecular skeleton and 2
(meth)acryloyl groups, usually up to 5, and particularly preferably a small number of (meth)acryloyl groups at both ends of the molecule, which improves elongation and flexibility of the cured adhesive. Provides flexibility.

Such urethane (meth)acrylates can be obtained by various methods, but are generally obtained from various polyols (polyether polyols, polyolefin polyols, polyester polyols, polycarbonate polyols,
Polycaprolactone polyol, etc.) is reacted with an isocyanate compound having two or more isocyanate groups in one molecule via the hydroxyl groups of this polyol to form a urethane bond, and the remaining isocyanate groups of the above compound involved in this bond are It can be obtained by introducing (meth)acryloyl groups to both ends of the molecule via.

Component (c) of the present invention acts as a reactive diluent for the components (a) and (b), and is particularly a compound that is liquid at room temperature and has one or more unsaturated double bonds. Although not limited, (meth)acrylate compounds are particularly preferably used.

Specific examples of such (meth)acrylate compounds include:
For example, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, nonylphenoxyethyl (meth)acrylate, (meth)acrylate of tetrahydrofurfuryl alcohol caprolactone adduct, bisphenol diethylene glycol di(meth)acrylate, tripropylene glycol diacrylate , trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, N-vinylpyrrolidone, N,N-dimethylacrylamide, styrene, and the like.

The long-chain alkyl (meth)acrylate used as component (d) in the present invention is an alkyl group represented by the following general formula, where R is an integer of 8 to 18 carbon atoms, preferably 8 to 14 carbon atoms. It is a compound.

R.sup.CHz = CCOORl (Rz is a hydrogen atom or a methyl group.) When the number of carbon atoms in R1 exceeds 18, the compound becomes waxy or solid, which is not preferable, while when it is less than 8, it is difficult to obtain The water resistance of the cured product is poor.

Such a long-chain alkyl (meth)acrylate as described above (
By using in combination with components a), (b) and (c),
An adhesive with excellent adhesive strength and water resistance can be obtained.

Specific examples of such long-chain alkyl (meth)acrylates include 2-ethylhexyl acrylate, lauryl acrylate, isodecyl acrylate, tridecyl acrylate, and stearyl acrylate.

Furthermore, as the photopolymerization initiator as component (e) in the present invention, various kinds of initiators and sensitizers that are generally used as initiators and sensitizers for ultraviolet curable resins can be used.

Specific examples include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether,
2-Methylbenzoin, benzophenone, Michler's ketone, benzyl, benzyl dimethyl ketal, benzyl diethyl ketal, anthraquinone, methyl anthraquinone, 2.2-jethoxyacetophenone, 2-methylthioxanthone, 2-isopropylthioxanthone, 2
Examples include -chlorothioxanthone, anthracene, 1,1-dichloroacetophenone, methylorthobenzoylbenzoate, and the like, or combinations of these with small amounts of sensitizing aids such as amines.

The photocurable adhesive composition of the present invention is made by uniformly mixing the above-mentioned components as essential components.

Here, the blending amount of component (a) is (a), mountain) and (c)
20-50% by weight based on the total amount of components, preferably 25-4%
5% by weight, if it is less than this range, the cured adhesive will lack cohesive force and adhesive strength, and if it exceeds the above range, the cured adhesive will lack flexibility and the viscosity of the adhesive will also significantly decrease. undesirable as it increases.

Also, the blending amount of component (b) is (a), mountain) and y (c)
10-30% by weight based on the total amount of components, preferably 15-2%
5% by weight, and if it is less than this range, the cured adhesive will lack flexibility, while if it is more than the above range, the cured adhesive will lack cohesive strength and the viscosity of the adhesive will increase significantly, so it is preferable. do not have.

In addition, the blending amount of component (c) is 20 to 40% by weight, preferably 25 to 30% by weight based on the total amount of components +a), mountain) and (c1).
If it is less than this range, the viscosity of the adhesive will become too high, while if it exceeds the above range, the viscosity will become too low, which is not preferable.

The blending amount of component (d) of the present invention is the above-mentioned (a), Tb),
It is desirable that the total amount of components (c) and (dl) be 5 to 30% by weight, preferably 10 to 25% by weight. If it is less than this range, the adhesive cured product will have sufficient adhesive strength and sufficient water resistance. On the other hand, if it exceeds the above range, the components will lack compatibility and become cloudy or separate, which is undesirable.

In addition, the blending amount of component (e) is as follows: (a), (b), (c)
Usually 0.1 to 10 parts by weight, preferably 0.1 to 10 parts by weight, per 100 parts by weight of the total amount of components 1 and (d). °5 to 5 parts by weight; if this amount is too small, curing properties cannot be satisfied;
Moreover, even if it is used beyond this range, no further improvement in the curing rate can be expected.

In addition, the photocurable adhesive composition of the present invention may contain various additives that impart adhesion, adhesive properties, etc., antioxidants,
One or more of various additives such as storage stabilizers and modified resins such as silicone resins and polyurethane resins may be contained as a window component of 0.1 to 10% by weight of the entire composition.

The photocurable adhesive composition of the present invention obtained by uniformly mixing these components can be cured by applying it to the surface of an object to be adhered, bonding it together, and curing it by irradiating it with light such as ultraviolet rays. , it is possible to form an adhesive layer with excellent adhesive strength and water resistance.

〔Effect of the invention〕

The photocurable adhesive composition of the present invention has excellent adhesive strength, water resistance, and long-term reliability, and can be suitably used as an adhesive, a sealant, and the like.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
Note that in the following, parts mean parts by weight.

Example 1 Bisphenol A type epoxy resin (
(Product name: Epicoat 1004, manufactured by Yuka Shell Epoxy Co., Ltd.)
Epoxy acrylate 4 obtained by reacting acrylic acid with
0 parts, as a component, polyoxytetramethylene glycol (trade name PTMG100O, manufactured by Sanyo Chemical Co., Ltd.) with a number average molecular weight of 1000, tolylene diisocyanate and 2-
10 parts of urethane acrylate obtained by reacting with hydroxyethyl acrylate, 20 parts of tetrahydrofurfuryl acrylate as component (c), 30 parts of lauryl acrylate as component (d), benzyl dimethyl kecour as component (e) 1 part of Irgacure 651 (trade name manufactured by Ciba Geigy) and 0.2 part of a silane coupling agent (trade name KBM403 manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed uniformly at 60 to 70°C for 2 hours, and then exposed to ultraviolet light. A curable adhesive composition was obtained.

Example 2 Same epoxy acrylate as Example 1 [(a) component 33
0 parts, urethane acrylate) (component (b)) 15 parts, lauryl acrylate (component (d) 325 parts, benzyldimethylkecour [component (e) 33 parts, silane coupling agent 0.2 part, and fat Cyclic diacrylate (tricyclo[5.2.1.02°6]decane-38 (or 3,9
or 4.8)-diyl dimethylene diacrylate)
(Component (0)) (Product name 5 manufactured by Mitsubishi Yuka Fine Co., Ltd.
A1002) were mixed in the same manner as in Example 1 to obtain an ultraviolet curable adhesive composition.

Example 3 As component (a), bisphenol A type epoxy resin (
Epoxy acrylate 35 obtained by reacting acrylic acid with Epicoat 828 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.)
part, same urethane acrylate component as in Example 1)
20 parts, lauryl acrylate) (component (d)) 25
2 parts, benzyldimethylkecool [component (e)] 2 parts, and pentaerythritol triacrylate) [component (c)] 20 parts, silane coupling agent (trade name KBM503 manufactured by Shin-Etsu Chemical Co., Ltd.) 0.2 parts were mixed in the same manner as in Example 1 to obtain an ultraviolet curable adhesive composition.

Example 4 An ultraviolet curable adhesive composition was obtained in the same manner as in Example 1, except that lauryl acrylate in Example 1 was changed to 2-ethylhexyl acrylate.

Example 5 The urethane acrylate of Example 2 was prepared with a number average molecular weight of 65.
An ultraviolet curable adhesive composition was obtained in the same manner as in Example 2, except that urethane acrylate obtained using No. 0 polyoxytetramethylene glycol (trade name: PTMG 650, manufactured by Sanyo Kasei Co., Ltd.) was used.

Comparative Example 1 As component (a), bisphenol A type epoxy resin (
(Product name: Epicoat 1004, manufactured by Yuka Shell Epoxy Co., Ltd.)
Epoxy acrylate 5 obtained by reacting acrylic acid with
As a component, polyoxytetramethylene glycol (trade name P manufactured by Sanyo Chemical Co., Ltd.) with a number average molecular weight of 1000 is used as a component.
50 parts of urethane acrylate obtained by reacting TMG100O) with tolylene diisocyanate and 2-hydroxyethyl acrylate, (tetrahydrofurfuryl acrylate as c1 component) 4561S, 3 parts of benzyl dimethyl ketal as component (e), and silane. 0.2 part of a coupling agent was blended and mixed uniformly at 60 to 70°C for 2 hours to obtain an ultraviolet curable adhesive composition.

Comparative Example 2 40 parts of the epoxy acrylate of Comparative Example 1, 50 parts of alicyclic acrylate of Example 2, 10 parts of tetrahydrofurfuryl acrylate, 3 parts of benzyl dimethyl ketal, and 0.2 parts of the silane coupling agent of Comparative Example 1. , Comparative Example 1
They were mixed in the same manner as above to obtain an ultraviolet curable adhesive composition.

Each composition obtained in the above Examples and Comparative Examples was mixed with PMMA.
(Polymethyl methacrylate) (width 25 x length 10
Apply it to a test piece with an adhesion area of 12.5 fim x 25 mm
An adhesion test piece was obtained by stacking and pressing with a clip so that the thickness was 1 mm.

The test piece was cured by irradiating ultraviolet light for 1 minute using a high-pressure mercury lamp of 80 W/cs, and
A cured adhesive layer of 50 μm was obtained.

This test piece was evaluated by the following method, and the obtained results are shown in the table.

11) Attach the tensile shear adhesive strength test piece to a tensile tester and test it at a specified temperature at lOam/
The shear adhesive strength was measured at a tensile rate of sin.

(2) Water resistance The test pieces obtained in (1) above were immersed in water at 23°C, taken out at predetermined temperature intervals, and the tensile shear adhesive strength was measured at 23°C in the same manner as in (1).

(3) A spacer (silicon rubber) with a thickness of 50 μm was provided on a hygroscopic glass plate, and an adhesive composition was cast on the surface of the spacer at 80 W/
After curing by irradiating ultraviolet light for 1 minute using a CS high-pressure mercury lamp, remove the spacer part and
After being left in a constant temperature machine at 0° C./90% R11, the sample was taken out at predetermined time intervals and the moisture absorption rate was determined using the following formula.

Moisture absorption rate (2) = Weight after standing (g) - Weight after curing (g) Weight after curing (g) xloo (χ) As is clear from the table, the adhesive composition of the present invention The resulting adhesive had excellent adhesive strength, low hygroscopicity, excellent water resistance, good curability, and high reliability.

On the other hand, the adhesive composition of the comparative example had poor water resistance and high moisture absorption rate.

Claims (2)

[Claims] (1) (a) Epoxy compound having one or more unsaturated double bonds in one molecule, (b) Urethane (meth)acrylate, (c) As a reactive diluent for components (a) and (b) above. (d) A long-chain alkyl (meth)acrylate represented by the general formula below, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_1 is carbon an alkyl group whose number is an integer from 8 to 18,
R_2 is a hydrogen atom or a methyl group. ), and (e
) A photocurable adhesive composition containing a photopolymerizable initiator. (2) (d) component is (a), (b), (c) and (d)
2. The photocurable adhesive composition according to claim 1, wherein the photocurable adhesive composition contains 5 to 30% by weight of the component (2).