JPH09183957A - Photocurable adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocurable adhesive compsn. which exhibits improved adhesive power, durability, and heat resistance in bonding metal plates to each other or a metal plate to another material and can strongly bond the adherends. SOLUTION: This adhesive compsn. mainly comprises a copolymer formed from ethylene, vinyl acetate, and an acrylate and/or a methacrylate monomer, contains a photosensitizer as a cross-linker (a curative) and pref. a silane coupling agent and an epoxy compd., and forms a cross-linking structure when cured, exhibiting high adhesive properties together with greatly improved durability and heat resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable adhesive composition used for bonding metal plates to metal plates or metal plates to other materials.

[0002]

2. Description of the Related Art Conventionally, as an adhesive for metal, (1)
Epoxy-based, acrylic-based, urethane-based, two-component mixed type or one-component solventless liquid reactive adhesives, and (2) hot melt adhesives using a thermoplastic resin are known.

[0003]

However, the liquid adhesive (1) is good for adhering a complicated shape,
When a plate-shaped member, particularly a large plate-shaped member, is bonded, there are problems such as air bleeding in the adhesive between the plates and the protrusion of the adhesive at the ends. Further, the hot melt adhesive using the thermoplastic resin of (2) can be provided in the form of a film or sheet by extrusion or calendering,
Although it does not have the above-mentioned problem (1), it has a weak adhesive force, poor durability, and heat resistance.

The present invention has been made in view of the above circumstances, and is a material that is generally widely used in the industrial fields of construction, automobiles, civil engineering, electronics, electricity, etc., particularly a metal plate and a metal plate or other materials. It is an object of the present invention to provide a photocurable adhesive composition capable of solving the above problems and firmly adhering.

[0005]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that ethylene, vinyl acetate, and a copolymer composed of acrylate and / or methacrylate monomers as main components. By using a photosensitizer as a crosslinking agent (curing agent), and preferably by adding a silane coupling agent and further an epoxy group-containing compound, a crosslinked structure is formed during curing. With high adhesion,
The inventors of the present invention have found that the durability and heat resistance can be greatly improved, and have accomplished the present invention.

That is, the present invention is: (1) A photocurable adhesive composition comprising a copolymer composed of ethylene, vinyl acetate and acrylate and / or methacrylate monomers as a main component. (2) 0.1 to 10 parts by weight of a photosensitizer and 0.01 to 100 parts by weight of a silane coupling agent based on 100 parts by weight of the above copolymer.
The photocurable adhesive composition according to (1), wherein the photocurable adhesive composition is added in an amount of 5 to 5 parts by weight. (3) The photocurable adhesive according to (1) or (2) above, wherein 0.1 to 20 parts by weight of an epoxy group-containing compound is added to 100 parts by weight of the copolymer. Composition. (4) 0.1 to 50 parts by weight of at least one of an acryloxy group-containing compound, a methacryloxy group-containing compound and an allyl group-containing compound is added to 100 parts by weight of the above copolymer. The photocurable adhesive composition according to (1), (2) or (3). (5) The photocurable adhesive composition according to any one of (1) to (4) above, which is for a metal. I will provide a.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The adhesive composition according to the present invention can be provided in the form of a sheet, and a metal plate and a metal plate having a large area or a metal plate and another material can be accurately manufactured with a good plate thickness, and the end portion can be protruded. It can be easily glued so that there is no such thing.
It can also be provided in a liquid form, and can be applied to a material, dried, bonded to an adherend, and cured and bonded. Hereinafter, the present invention will be described in detail. The photocurable adhesive composition of the present invention comprises ethylene, vinyl acetate and acrylate-based and / or
Alternatively, it contains a copolymer composed of a methacrylate monomer as a main component. Ethylene used in the present invention,
The vinyl acetate content of the copolymer composed of vinyl acetate and acrylate-based and / or methacrylate-based monomers is preferably 4 to 50% by weight, and more preferably 14 to 45% by weight. Vinyl acetate content is 4% by weight
If it is lower, a sufficient degree of crosslinking cannot be obtained when it is crosslinked and cured at a high temperature. On the other hand, if it exceeds 50% by weight, the softening temperature of the resin tends to be low and storage may be difficult.

Examples of the acrylate-based monomer and the methacrylate-based monomer include acrylic acid, methacrylic acid, and their esters. Specifically, (meth) acrylate, ethyl (meth) acrylate and the like ( In addition to (meth) acrylic acid lower alkyl ester, glycidyl (meth) acrylic acid and the like are exemplified. These may be used alone or in combination of two or more, but the content of the acrylate-based and methacrylate-based units in the copolymer is 0.01 to 10% by weight, particularly It is preferably 0.05 to 5% by weight. If this content exceeds 10% by weight, the workability may decrease.

The photosensitizer (photopolymerization initiator) added for curing the adhesive composition of the present invention includes a hydrogen abstraction type initiator, an intramolecular cleavage type initiator and an α-hydroxyalkylphenone type. A radical photopolymerization initiator such as an initiator or an α-aminoalkylphenone type initiator is preferably used. Examples of the hydrogen abstraction type initiator include benzophenone, methyl orthobenzoylbenzoate, 4-benzoyl-4′-methyldiphenylsulfide, isopropylthioxanthone, diethylthioxanthone, ethyl-4.
Examples thereof include- (diethylamino) benzoate. Examples of the intramolecular cleavage type initiator include benzoin ether and benzyl dimethyl ketal. Examples of the α-hydroxyalkylphenone type initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, alkylphenylglyoxylate, diethoxyacetophenone and the like. 2-methyl-1 as an α-aminoalkylphenone type initiator
-[4- (Methylthio) phenyl] -2-morpholinopropane-1,2-benzyl-2-dimethylamino-1
Examples thereof include-(4-morpholinophenyl) -butanone-1, acylphosphine oxide and the like.
The above photosensitizers may be used alone or in combination of two or more, and the addition amount is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the above copolymer. .

The adhesive composition of the present invention may optionally contain an organic peroxide in addition to the above-mentioned photosensitizer, whereby the photocuring and the thermosetting can be used together. . As the organic peroxide to be added, any one can be used as long as it decomposes at a temperature of 70 ° C. or higher to generate a radical, but the decomposition temperature with a half-life of 10 hours is 5
Those having a temperature of 0 ° C. or higher are more preferable. Examples of usable organic peroxides include 2,5-dimethylhexane-2,5
-Dihydroxy peroxide, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexyne-3, di-t-butylperoxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane , Dicumyl peroxide, α,
α'-bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4'-bis- (t-butylperoxy) valerate, 1,1-bis (t-butylperoxy) cyclohexane, 1, 1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, t
-Butyl peroxy benzoate, t-butyl peroxy acetate, methyl ethyl ketone peroxide,
2,5-dimethylhexyl-2,5-bisperoxybenzoate, butyl hydroperoxide, p-methane hydroperoxide, p-chlorobenzoyl peroxide, hydroxyheptyl peroxide, chlorohexanone peroxide, octanoyl peroxide, Decanoyl peroxide, lauroyl peroxide, cumyl peroxide octoate, succinic acid peroxide, acetyl peroxide, t
-Butylperoxy (2-ethylhexanoate), m
-Toluoyl peroxide, benzoyl peroxide, t-butyl peroxyisobutyrate, 2,4-dichlorobenzoyl peroxide and the like can be mentioned. As the organic peroxide, one of these may be used alone or in combination of two or more, and the addition amount thereof is 0 to 10 parts by weight, particularly 0.1. It can be 1 to 10 parts by weight.

Further, a silane coupling agent can be added as an adhesion promoter to the adhesive composition of the present invention. As this silane coupling agent, vinyltriethoxysilane, vinyltris (β-methoxyethoxy)
Silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane , Vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane,
There are γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane and the like, and one of these can be used alone or two or more can be used in combination. The addition amount of these silane coupling agents is usually 0.0 with respect to 100 parts by weight of the above copolymer.
1 to 5 parts by weight is sufficient.

Furthermore, it is preferable to add an epoxy group-containing compound other than epoxysilane to the adhesive composition of the present invention as an adhesion promoter. Examples of such an epoxy group-containing compound include triglycidyl tris (2-hydroxyethylene) isocyanurate, neopentyl glycol diglycidyl ether, 1,6-hexanediol glycidyl ether, allyl glycidyl ether,
-Ethylhexyl glycidyl ether, phenyl glycidyl ether, phenol (EO) 5 glycidyl ether, p-t-butylphenyl glycidyl ether, adipic acid diglycidyl ester, o-phthalic acid glycidyl ester, glycidyl methacrylate, butyl glycidyl ether and the like can be mentioned. The same effect can be obtained by alloying a polymer containing an epoxy group. These epoxy group-containing compounds can be used alone or in combination of two or more, and the addition amount is usually 0.1 to 2 with respect to 100 parts by weight of the above copolymer.
0 parts by weight is sufficient.

Further, the adhesive composition of the present invention contains acryloxy for improving and controlling its physical properties (mechanical strength, adhesiveness, optical characteristics, heat resistance, moist heat resistance, weather resistance, crosslinking rate) and the like. Compounds containing groups, methacryloxy groups or allyl groups can be added. Most commonly used compounds for this purpose are acrylic acid or methacrylic acid derivatives such as their esters and amides. In this case, the ester residues include methyl, ethyl, dodecyl,
1 to 24 carbon atoms such as stearyl and lauryl, especially 1
To 18 alkyl groups, cycloalkyl groups such as cyclohexyl groups, tetrahydrofurfuryl groups, aminoethyl groups, 2-hydroethyl groups, 3-hydroxypropyl groups, 3-chloro-2-hydroxypropyl group-based halogen substitution , Hydroxyl group substitution, amino substitution, and other substituted alkyl groups. Further, esters of acrylic acid or methacrylic acid with a polyfunctional alcohol such as ethylene glycol, triethylene glycol, polyethylene glycol, glycerin, trimethylolpropane, pentaerythritol and the like are also used. A typical amide is diacetone acrylamide. Further, acrylic or methacrylic acid esters such as trimethylolpropane, pentaerythritol, and glycerin can be used as the polyfunctional crosslinking aid.

Examples of the allyl group-containing compound include triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl isophthalate, diallyl maleate and the like. 0.1 to 50 per 100 parts by weight of the copolymer
Parts by weight, preferably 0.1 to 30 parts by weight are added and used. If it is less than 0.1 part by weight, the improving effect of improving the mechanical strength may be lowered, and if it exceeds 50 parts by weight, workability and film-forming property during preparation of the adhesive may be lowered.

A hydrocarbon resin may be added to the adhesive composition of the present invention for the purpose of improving workability and workability such as bonding. In this case, the hydrocarbon resin added may be either a natural resin type or a synthetic resin type. Rosin, rosin derivatives, and terpene resins are preferably used in the natural resin system. For rosin, gum-based resins, tall oil-based resins, and wood-based resins can be used. As the rosin derivative, rosin obtained by hydrogenation, heterogeneization, polymerization, esterification, and metal salification can be used.

As the terpene-based resin, a terpene-phenol resin can be used in addition to the terpene-based resin such as α-pinene and β-pinene. Further, other natural resins such as dammar, cobal and shellac may be used. On the other hand, in the case of synthetic resins, petroleum resins, phenol resins, and xylene resins are preferably used. As the petroleum-based resin, aliphatic petroleum resin, aromatic petroleum resin, alicyclic petroleum resin, copolymer-based petroleum resin, hydrogen-based resin, pure monomer-based petroleum resin, and coumarone-indene resin can be used. As the phenolic resin, an alkylphenol resin and a modified phenol resin can be used. As the xylene-based resin, a xylene resin or a modified xylene resin can be used.

The amount of the above-mentioned hydrocarbon resin added is appropriately selected, but a copolymer 10 comprising ethylene, vinyl acetate and acrylate and / or methacrylate monomers is used.
The amount is 0 to 200 parts by weight, preferably 1 to 200 parts by weight, more preferably 5 to 150 parts by weight, based on 0 parts by weight.

In addition to the above additives, the adhesive composition of the present invention may contain an antiaging agent, an anti-UV agent, a dye, a processing aid, etc. within a range that does not impair the effects of the present invention.

Examples of metals to be adherends of the adhesive composition of the present invention include iron, aluminum, tin, nickel, chromium, stainless steel, copper, zinc and brass. To bond these metals. In addition to the above-mentioned crosslinking agent generating a heat radical, a crosslinking aid, a silane coupling agent, an epoxy group-containing compound, etc. are added to a copolymer composed of ethylene, vinyl acetate and acrylate and / or methacrylate monomers. Is preferred. Here, in the case of metals such as iron and aluminum that are relatively easily adhered, the allowable range of the blending amount is quite wide, while in the case of relatively soft metals such as copper and zinc, a crosslinking agent to be added,
If the crosslink density of the adhesive layer is increased too much by the crosslinking aid (95% or more in gel fraction), the rigidity of the metal and the adhesive layer will be different, and the adhesive interface will be easily distorted and the adhesiveness may decrease. On the contrary, if the amount before crosslinking is excessively reduced, sufficient adhesiveness may not be obtained. Therefore, when the adhesive composition according to the present invention is produced, the crosslink density of the adhesive depends on the adherend,
Although it is preferable to control the amount of the adhesion-imparting agent, it is preferable that the crosslink density is usually 10 to 98%, particularly 20 to 96% in terms of gel fraction. The method for measuring the gel fraction is 8
It was calculated from the weight change rate before and after extraction with hot toluene at 0 ° C.

To carry out the present invention, a copolymer composed of ethylene, vinyl acetate and acrylate and / or methacrylate monomers and the above-mentioned additives are uniformly mixed and kneaded by an extruder, a roll or the like. After that, this can be used by forming a film into a desired shape by a film forming method such as calendering, rolling, T-die extrusion, and inflation. At the time of film formation, embossing may be performed for the purpose of preventing blocking, facilitating pressure bonding with an adherend, and the like. The sheet obtained as described above can be attached to a member by a conventional method. For example, lamination can be performed by using a method such as a hot pressing method, a direct laminating method using an extruder or a calendar, or a thermocompression bonding method using a film laminator.
Further, each component can be uniformly dissolved in a solvent that does not affect the member, applied uniformly on the surface of the member, temporarily press-bonded with another member, or can be photocured as it is. As the curing conditions of the adhesive composition of the present invention, many that are generated in the ultraviolet to visible region as a light source can be adopted, for example, ultra-high pressure, high pressure, low pressure mercury lamp, chemical lamp, xenon lamp, halogen lamp, Mercury. Halogen lamps, carbon arc lamps, incandescent lamps, laser light and the like can be mentioned. The irradiation time is appropriately selected depending on the type of lamp and the strength of the light source, but is about tens of seconds to tens of minutes. Further, in order to accelerate curing, the laminate is preliminarily 40 to 12
It may be heated to 0 ° C. and irradiated with ultraviolet rays. Also,
Curing is preferably carried out under a pressure of 0.01 to 50 kgf / mm ² , particularly 0.1 to 20 kgf / mm ² .

[0021]

EFFECT OF THE INVENTION Since the adhesive composition of the present invention is a photocurable adhesive containing a copolymer of ethylene, vinyl acetate and acrylate and / or methacrylate monomers as a main component, it has transparency and weather resistance. Since it has excellent properties, and particularly has a cross-linked structure by a photosensitizer, heat resistance, moist heat resistance, and transparency are improved. In addition, the addition of a silane coupling agent and an epoxy group-containing compound improves the adhesiveness associated with photocuring, and the initial adhesive strength and the adhesive strength with excellent thermal stability are obtained, and the addition of a crosslinking agent and a crosslinking auxiliary agent. Since the amount can be freely changed and the crosslink density can be controlled, a wide variety of adhesives can be designed, and adhesion between metal and any member can be obtained.
Therefore, the adhesive composition of the present invention is applied to a metal plate such as polyester, polycarbonate, polyvinyl alcohol, polyethylene-vinyl alcohol for the purpose of protecting the surface of the metal plate used outdoors or in a place where scratches are unlikely to occur. It is effective as an adhesive when laminating transparent films such as, and this enables laminating and bonding with excellent heat resistance and heat and moisture resistance, and since the adhesive composition is colorless and transparent, the appearance such as the color of the metal plate Will not hurt.

[0022]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 and 2 and Comparative Example 1] 100 parts by weight of a copolymer comprising ethylene, vinyl acetate, and an acrylate-based and / or methacrylate-based monomer,
Add each component shown in Table 1 and mix with a mixing roll to 85
After sufficiently kneading so that the respective components were uniform at a temperature of ° C, a film having a thickness of 0.4 mm was formed by a calender method. This sheet is sandwiched between each adherend and separator, 4kW
It was irradiated with the UV irradiation device for 3 minutes for photo-curing. Create a 2 layer structure consisting of each member / thermosetting adhesive layer
It was cut into a width of 5 mm and the adhesive force between them was measured (pulling speed 100 mm / min). Table 2 shows the results.

[0024]

[Table 1]

[0025]

[Table 2]

[Example 3 and Comparative Example 2] The adhesive composition having the composition of Example 1 was dissolved in xylene so that the content of the adhesive composition was 15% by weight, and the solution was mixed with P using a precision coater.
The ET film was uniformly applied so that the thickness of the adhesive layer after drying was 30 μm. This was temporarily pressure-bonded to a stainless steel plate to form a three-layer structure of PET (25 μm) / adhesive layer / stainless steel plate (1 mm), and then irradiated with a 4 kW UV irradiation device for 3 minutes to be photocured. PE for comparison
A three-layer laminate of T / ethylene-ethyl acrylate adhesive layer / stainless plate was prepared. In order to compare the moist heat resistance and heat resistance characteristics of both, 100 at 50 ° C, 90% RH
A wet heat test was performed for 0 hours, and the adhesive force before and after the test was measured. The results are shown in Table 3. Furthermore, both are 100 mm x 10
It was cut into 0 mm and subjected to a heat resistance test for 2 hours in an oven at 100 ° C. As a result, the sample using the adhesive composition of the present invention showed no change in appearance. On the other hand, the sample using the ethylene-ethyl acrylate-based thermosetting adhesive has PET of about 5 mm from the end.
Film peeling was observed.

[0027]

[Table 3]

Claims (5)

[Claims] 1. A photocurable adhesive composition comprising a copolymer composed of ethylene, vinyl acetate and acrylate and / or methacrylate monomers as a main component. 2. A photosensitizer of 0.1 to 10 parts by weight and a silane coupling agent of 0.01 to 5 parts by weight are added to 100 parts by weight of the copolymer. Item 2. The photocurable adhesive composition according to item 1. 3. The photocurable adhesive according to claim 1, wherein 0.1 to 20 parts by weight of an epoxy group-containing compound is added to 100 parts by weight of the copolymer. Composition. 4. At least one of an acryloxy group-containing compound, a methacryloxy group-containing compound and an allyl group-containing compound is added to 0.1 to 100 parts by weight of the copolymer.
50 parts by weight is added, and it is characterized by the above-mentioned.
Alternatively, the photocurable adhesive composition according to Item 3. 5. The method according to claim 1, which is for metal.
6. The photocurable adhesive composition according to any one of items 1 to 5.