JPH10338857A - Adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive compsn. which can strongly bond materials, esp. a metal sheet to another metal sheet or to other materials, widely used in many industiral fields, such as building, automotive, civil engineering, electronic, and electric industries by using an ethylene-ethyl acrylate copolymer as the main ingredient. SOLUTION: Pref. the copolymer used has an ethyl acrylate content of 5-50 wt.%. An org. peroxide or a photosensitizer for curing is incorporated into this compsn. A silane coupling agent can be incoporated as an adhesion promotor, and further incorporation of an epoxy compd. other than an epoxysilane as an adhesion promotor is pref. In order to improve or adjust the physical properties, etc., a compd. having an acryloxy, methacryloxy, or allyl group can be incorporated. A hydrocarbon resin can also be incroprated to improve processibilities such as fabricability and laminatability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting or photocurable adhesive composition used for bonding a metal plate to a metal plate or a metal plate to another material.

[0002]

2. Description of the Related Art
As adhesives for metals, (1) epoxy-based, acrylic-based, urethane-based, two-component mixed type or one-component non-solvent liquid reactive adhesives (2) hot-melt adhesives using a thermoplastic resin are known. Have been.

[0003] However, the liquid adhesive (1) is good for bonding a complicated shape, but when bonding a plate-shaped material, especially a large plate-shaped material, a plate and a plate are required. There is a problem such as air bleeding out of the adhesive between them and the adhesive running out at the end. 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 there is no such problem as described above, the adhesive strength is weak, the durability is poor, and there is also a problem in heat resistance.

[0004] The present invention has been made in view of the above circumstances,
Materials widely used in the industrial fields such as construction, automobiles, civil engineering, electronics, and electricity, etc., in particular, a metal plate and a metal plate or other materials can be firmly bonded by solving the above problems. It is an object of the present invention to provide an adhesive composition that can be used.

[0005]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that an ethylene-ethyl acrylate copolymer is used as a main component. Particularly, by using an organic peroxide or a photosensitizer as a cross-linking agent (curing agent), and preferably by adding a silane coupling agent and further an epoxy group-containing compound, a cross-linked structure is formed upon curing. In addition, the present inventors have found that high adhesiveness can be obtained and durability and heat resistance can be significantly improved, and the present invention has been accomplished.

That is, the present invention provides the following adhesive composition. Claim 1: An adhesive composition comprising an ethylene-ethyl acrylate copolymer as a main component. (2) The adhesive composition according to the above (1), wherein the copolymer has an ethyl acrylate content of 5 to 50% by weight. Claim 3: The adhesive composition according to claim 1 or 2, wherein 0.1 to 10 parts by weight of an organic peroxide and / or a photosensitizer is added to 100 parts by weight of the copolymer. In a preferred embodiment, 0.01 to 5 parts by weight of a silane coupling agent is added to 100 parts by weight of the copolymer.
4. The adhesive composition according to 2 or 3. (5) The adhesive composition according to any one of (1) to (4), wherein an epoxy group-containing compound is added in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the copolymer. In another embodiment, at least one of an acryloxy group-containing compound, a methacryloxy group-containing compound, and an allyl group-containing compound is present in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the copolymer.
The adhesive composition according to any one of claims 1 to 5, wherein 0 part by weight is added.

In this case, the above-mentioned adhesive composition is suitably used for metals. The adhesive composition according to the present invention can be provided in the form of a sheet, and a metal sheet and a metal sheet of a large area or a metal sheet and another material can be easily formed with high plate thickness accuracy and without protruding edges. Can be glued.
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 adhesive composition of the present invention contains an ethylene-ethyl acrylate copolymer as a main component. The ethyl acrylate content of the ethylene-ethyl acrylate copolymer used in the present invention is preferably 5 to 50% by weight, more preferably 10 to 45% by weight. If the ethyl acrylate content is less than 5% by weight, a sufficient degree of crosslinking cannot be obtained when crosslinking and curing at a high temperature. On the other hand, if it exceeds 50% by weight, the softening temperature of the resin becomes low, which may make storage difficult. is there.

An organic peroxide or a photosensitizer is added to the adhesive composition according to the present invention for curing. As the organic peroxide to be added, any organic peroxide can be used as long as it decomposes at a temperature of 70 ° C. or more to generate radicals, but one having a half-life decomposition time of 10 hours of 50 ° C. or more is more preferable. It can be selected and used in consideration of film formation temperature, preparation conditions, curing (lamination) temperature, heat resistance of the adherend, storage stability, and the like.

Examples of usable organic peroxides include, for example, 2,5-dimethylhexane-2,5-dihydroxy peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne- 3, di-t-butyl peroxide, t-butyl cumyl 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-butylperoxybenzoate, t-butylperoxyacetate,
Methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, butyl hydroperoxide, p-methane hydroperoxide, p-chlorobenzoyl peroxide, hydroxyheptyl peroxide, chlorohexanone peroxide, octa Noyl peroxide, decanoyl peroxide, lauroyl peroxide, cumyl peroxy octoate, succinic acid peroxide, acetyl peroxide, t-butyl peroxy (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 is used.
Species can be used alone or as a mixture of two or more,
The amount added is 0.1 to 100 parts by weight of the copolymer.
It is preferably 10 parts by weight.

The photosensitizer (photopolymerization initiator) added for curing the adhesive composition of the present invention includes a hydrogen abstraction initiator, an intramolecular cleavage initiator, an α-hydroxyalkyl Radical photopolymerization initiators such as phenone-type initiators and α-aminoalkylphenone-type initiators are preferably used.

Examples of the hydrogen abstraction initiator include benzophenone, methyl orthobenzoylbenzoate, 4-benzoyl-4'-methyldiphenylsulfide, isopropylthioxanthone, diethylthioxanthone, and ethyl-4- (diethylamino) benzoate. .

Examples of the intramolecular cleavage initiator include benzoin ether and benzyldimethyl ketal.

Examples of the α-hydroxyalkylphenone type initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, alkylphenylglyoxylate, and diethoxyacetophenone. Can be.

As an α-aminoalkylphenone type initiator, 2-methyl-1- [4- (methylthio) phenyl]
-2-morpholinopropane-1, 2-benzyl-2-
Dimethylamino-1- (4-morpholinophenyl)-
Butanone-1, acylphosphon oxide and the like can be mentioned.

The above-mentioned photosensitizers can be used alone or as a mixture of two or more, and the amount added is 0.1 to 10 parts by weight based on 100 parts by weight of the copolymer. Is preferred. The organic peroxide and the photosensitizer can be used in combination. Furthermore, in the adhesive composition of the present invention,
A silane coupling agent can be added as an adhesion promoter. Examples of the silane coupling agent include vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxy. Propyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β
(Aminoethyl) -γ-aminopropyltrimethoxysilane and the like, and one of these can be used alone or as a mixture of two or more. The addition amount of these silane coupling agents is usually 0.01 to 5 parts by weight based on 100 parts by weight of the copolymer.

Further, it is preferable that an epoxy group-containing compound other than epoxysilane is added to the adhesive composition of the present invention as an adhesion promoter. Examples of such epoxy group-containing compounds 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, pt-butylphenyl glycidyl ether, diglycidyl adipate, glycidyl o-phthalate, glycidyl methacrylate, butyl glycidyl ether and the like. A similar 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.
Parts by weight are sufficient.

The adhesive composition of the present invention is used for improving and controlling its physical properties (mechanical strength, adhesiveness, optical properties, heat resistance, wet heat resistance, weather resistance, crosslinking speed) and the like. An acryloxy group, methacryloxy group or allyl group-containing compound can be added.

As the compound used for this purpose, acrylic acid or methacrylic acid derivatives, for example, esters and amides thereof are most common. In this case, as the ester residue, in addition to an alkyl group having 1 to 24 carbon atoms, particularly 1 to 18 carbon atoms such as methyl, ethyl, dodecyl, stearyl, and lauryl, a cycloalkyl group such as a cyclohexyl group, and tetrahydrofurfuryl Group, aminoethyl group, 2-hydroethyl group, 3-hydroxypropyl group,
Examples include halogen substitution such as 3-chloro-2-hydroxypropyl group, hydroxyl substitution, amino substitution, and other substituted alkyl groups. Esters of acrylic acid or methacrylic acid with polyfunctional alcohols such as ethylene glycol, triethylene glycol, polyethylene glycol, glycerin, trimethylolpropane, and pentaerythritol are also used. As the amide, diacetone acrylamide is typical. Furthermore, acrylic or methacrylic acid esters such as trimethylolpropane, pentaerythritol and glycerin can also be used as the polyfunctional crosslinking assistant. Examples of the allyl group-containing compound include triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl isophthalate, diallyl maleate and the like.
The seed or a mixture of two or more kinds thereof is used in an amount of 0.01 to 50 parts by weight, preferably 0.01 to 50 parts by weight, based on 100 parts by weight of the copolymer.
0 parts by weight are used. If the amount is less than 0.01 part by weight, the effect of improving the mechanical strength may be reduced, and if the amount is more than 50 parts by weight, workability and film forming property at the time of preparing the adhesive may be reduced.

Further, a hydrocarbon resin can be added to the adhesive composition of the present invention for the purpose of improving processability such as processability and bonding. In this case, the hydrocarbon resin to be added may be either a natural resin or a synthetic resin. 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 rosin derivatives, rosin is hydrogenated, heterogeneous,
Polymerized, esterified, metal-chlorinated ones can be used. As the terpene-based resin, terpene-based resins such as α-pinene and β-pinene, as well as terpene phenol resins can be used. Also, dammar, corval, and shellac may be used as other natural resins. On the other hand, in the case of synthetic resins, petroleum resins, phenol resins, and xylene resins are preferably used. Petroleum resins include aliphatic petroleum resins, aromatic petroleum resins, alicyclic petroleum resins,
Copolymer petroleum resins, hydrogenated petroleum resins, pure monomer petroleum resins, and coumarone indene resins 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 hydrocarbon resin to be added is appropriately selected, but is preferably 0 to 200 parts by weight, more preferably 1 to 200 parts by weight, more preferably 5 to 200 parts by weight based on 100 parts by weight of the ethylene-ethyl acrylate copolymer. １５０150 parts by weight.

In addition to the above additives, an antioxidant, an ultraviolet absorber, a dye, a processing aid and the like can be added to the adhesive composition of the present invention in a range not to impair the effects of the present invention.

The metal to be adhered to the adhesive composition of the present invention includes iron, aluminum, tin, nickel, chromium, stainless steel, copper, zinc, brass and the like. In order to adhere these metals, the above-mentioned radical generating cross-linking agent is added, but a cross-linking aid, a silane coupling agent, an epoxy group-containing compound, etc. are added to the ethylene-ethyl acrylate copolymer. preferable. Here, in the case of relatively easy-to-adhesive metals such as iron and aluminum, the allowable range of the compounding amount is considerably wide, while, in the case of relatively soft metals such as copper and lead, a crosslinking agent to be added is used.
If the crosslinking density of the adhesive layer is excessively increased by the crosslinking assistant (95% or more in gel fraction), the rigidity between the metal and the adhesive layer is different, and distortion is likely to occur at the bonding interface, which may lower the adhesiveness. On the contrary, if the amount before crosslinking is excessively reduced, sufficient adhesiveness may not be obtained.

Therefore, when producing the adhesive composition according to the present invention, it is preferable to control the cross-link density of the adhesive and the amount of the adhesion-imparting agent depending on the adherend. It is preferably 98%, particularly preferably 20 to 96%. The method of measuring the gel fraction is a value calculated from the weight change rate before and after extraction with hot toluene at 80 ° C.

In order to carry out the present invention, the ethylene-ethyl acrylate copolymer and the above-mentioned additives are uniformly mixed, kneaded with an extruder, a roll, etc., and then calendered, rolled, T-die extruded, The film can be formed into a desired shape by a film forming method such as inflation and used. 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 bonded to a member by a conventional method. For example, lamination can be performed using a method such as a laminating method using a hot press, a direct laminating method using an extruder or a calender, or a thermocompression bonding method using a film laminator.

It is also possible to dissolve each component uniformly in a solvent that does not affect the member at all, apply it uniformly to the surface of the member and temporarily press-bond it to other members, or heat or light cure it as it is. it can.

The curing conditions for the adhesive composition of the present invention depend on the type of the organic peroxide used when an organic peroxide is used as a crosslinking agent (curing agent).
170 ° C, especially 70-150 ° C for 2-60 minutes, especially 5-5
Desirably, it is 30 minutes. The curing is preferably performed at 0.01 to 50 kgf / mm ² , particularly 0.1 to ²⁰ kf / mm ² .
It is recommended to work under pressure of gf / mm ² .

When a photosensitizer is used, as a curing condition, many light sources having a wavelength in the ultraviolet to visible region can be used, for example, an ultra-high pressure, high pressure, low pressure mercury lamp,
Examples include a chemical lamp, a xenon lamp, a halogen lamp, a mercury halogen lamp, a carbon arc lamp, an incandescent lamp, and a laser beam. The irradiation time is appropriately selected depending on the type of the lamp and the intensity of the light source, but several tens of seconds to
It is about tens of minutes. Alternatively, the laminate may be heated to 40 to 120 ° C. in advance to promote curing, and irradiated with ultraviolet rays. The curing is preferably performed at 0.01 to 50 kgf.
/ Mm ² , especially 0.1 to 20 kgf / mm ² is recommended.

[0031]

The adhesive composition of the present invention is a heat- or photo-curable adhesive containing an ethylene-ethyl acrylate copolymer as a main component, and therefore has excellent transparency and weather resistance, and particularly, an organic peroxide. Alternatively, since it has a crosslinked structure by a photosensitizer, heat resistance, heat and humidity resistance, and transparency are improved. In addition, the addition of a silane coupling agent and an epoxy group-containing compound improves the adhesiveness due to heat curing, provides an initial adhesive strength, an adhesive strength with excellent thermal stability, and adds a crosslinking agent and a crosslinking aid. Since the amount can be freely changed and the crosslink density can be controlled, the adhesive can be designed in various ways, and the adhesion between the metal and all members can be obtained.

Therefore, the adhesive composition of the present invention can be used for protecting a metal plate used outdoors, for example, or where it is easily damaged, for example, polyester, polycarbonate, polyvinyl alcohol, polyethylene, etc. -Effective as an adhesive when laminating a transparent film such as vinyl alcohol,
Adhesive bonding with excellent heat and moisture resistance is possible, and since the adhesive composition is colorless and transparent, such as the color of the metal plate,
Does not impair the appearance.

[0033]

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 1-4, Comparative Examples 1 and 2 The components shown in Table 1 were uniformly mixed and dissolved in toluene at 40 ° C. to prepare a toluene solution having a solute concentration of 20%. Using a reverse roll coater on a polyimide film having a thickness of 25 μm, this solution was used to produce a laminate having a thermosetting adhesive layer having a dry thickness of 25 ± 1 μm and a film thickness accuracy. This laminate was placed on a copper plate or a stainless steel plate to form a laminate, placed in a bag for degassing, degassed, and kept in that state in an oven at 100 ° C. for 30 minutes.
After the completion of the heating, the samples were taken out of the bag, cut out from each sample to a width of 1 inch, and 100 m in a tensile tester.
A tensile test was performed at a tensile speed of m / min. Table 2 shows the results
Shown in

[0035]

[Table 1]

[0036]

[Table 2]

[Examples 5 and 6] Using the components shown in Table 3, a laminate was prepared in the same manner as in Example 1, and
Preliminary heating and curing were performed for 15 minutes using a hot press machine heated to ℃. 4 kW UV from the separator side of this laminate
Irradiation with a lamp (mercury) was performed for 30 seconds to light cure. Thereafter, the adhesive strength was measured in the same manner as in Example 1. Table 4 shows the results.

[0038]

[Table 3]

[0039]

[Table 4]

Claims (6)

[Claims] 1. An adhesive composition comprising an ethylene-ethyl acrylate copolymer as a main component. 2. The adhesive composition according to claim 1, wherein the copolymer has an ethyl acrylate content of 5 to 50% by weight. 3. The adhesive composition according to claim 1, wherein 0.1 to 10 parts by weight of an organic peroxide and / or a photosensitizer is added to 100 parts by weight of the copolymer. 4. The adhesive composition according to claim 1, wherein 0.01 to 5 parts by weight of a silane coupling agent is added to 100 parts by weight of the copolymer. 5. The adhesive composition 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. 6. An amount of at least one of an acryloxy group-containing compound, a methacryloxy group-containing compound and an allyl group-containing compound, relative to 100 parts by weight of the copolymer, is 0.01%.
The adhesive composition according to any one of claims 1 to 5, wherein the adhesive composition is added in an amount of 50 to 50 parts by weight.