JPH11158451A - Reactive hot melt adhesive composition and method for bonding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactive hot melt adhesive composition which has pressure-sensitive adhesiveness in the initial state, cures upon irradiation with light to give a cured product having little pressure-sensitive adhesiveness and having excellent heat-resistant adhesiveness. SOLUTION: There are provided a reactive hot melt adhesive composition comprising an acrylic copolymer containing an alkyl (meth)acrylate with a 4-12C alkyl and a vinyl monomer, a cationically polymerizable compound, and a cationic photopolymerization initiator for curing the cationically polymerizable compound by irradiation with light and having a softening point in the range of 40-180 deg.C as measured by the ring and ball method and a method for bonding which comprises: melting the reactive hot melt adhesive composition by heating and applying the melt at least are of the adherends to be bonded; sticking the adherends together after irradiation with light; and pressure-bonding them together at ordinary temperature or under heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactive hot-melt adhesive composition which is applied by heat-melt coating and cures when irradiated with light, a method for producing the same, and a bonding method using the same. The present invention relates to a reactive hot melt adhesive composition having tackiness in an initial state, excellent workability, and excellent heat resistance after curing by light irradiation, a method for producing the same, and a method for bonding the same.

[0002]

2. Description of the Related Art Hot melt adhesives are widely used to bond paper, fiber, wood, glass, plastic or metal in various fields such as bookbinding, wrapping, textile processing, woodworking, light electric or transportation. ing.

[0003] In bonding with a hot melt adhesive, the hot melt adhesive is usually heated and melted at a temperature of about 100 to 200 ° C in an applicator. next,
A hot melt adhesive in a molten state is applied to the adherends, and the adherends are attached to each other. The adherends are bonded to each other by cooling and solidifying the hot melt adhesive.

[0004] In the case of hot melt adhesives, the adhesive strength is rapidly increased by cooling and solidification. Therefore, the time from bonding the adherends to realizing sufficient adhesive strength is very short, usually 1 minute or less. Therefore, the bonding operation can be completed in a short time.

On the other hand, there has been proposed a hot-melt type pressure-sensitive adhesive composition which is cured by irradiating ultraviolet rays (JP-A-8-60127). In this hot-melt pressure-sensitive adhesive composition, an acrylic copolymer is used, and the pressure-sensitive adhesive properties at high temperatures, particularly, holding power, are improved.

However, since it is a pressure-sensitive adhesive, its holding power is limited, and its tackiness remains even after curing. For example, when manufacturing a partition panel, a hot melt adhesive may be applied to a cloth and the cloth may be bonded to a woodworking board.
In such a case, if stickiness remains in the hot-melt adhesive after bonding, paper or sheet is fixed to the partition panel with a pin for display, and when the display becomes unnecessary, the pin is inserted. When pulled out, the adhesive will adhere to the pin tip.

[0007] In other uses, there is also a problem that dust and the like adhere to the hot-melt pressure-sensitive adhesive protruding from the adherend and impair the appearance.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bonding method which has adhesive properties for a while even after light irradiation, and can be used for a long period of time such as a manual operation or a low-speed line. A reactive hot-melt adhesive composition, which has excellent holding power at high temperatures and has no residual tackiness after curing, because the curing proceeds later by a dark reaction and cures until the tackiness is lost. An object of the present invention is to provide a method for producing a melt adhesive and a bonding method.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and the reactive hot melt adhesive composition according to the first aspect of the present invention has 4 carbon atoms. An acrylic copolymer of an alkyl (meth) acrylate having an alkyl group of from 12 to 12 and a vinyl monomer, a cationically polymerizable compound, and a cationically polymerizable initiator for curing the cationically polymerizable compound by irradiation with light,
The softening point according to the ring and ball measuring method is in the range of 40 to 180 ° C.

In the first aspect of the present invention, preferably, as described in the second aspect, the cationically polymerizable compound has an average of one or more of the following formula (1) per molecule.
Or an epoxy compound having an average of one or more epoxy groups per molecule.

[0011]

Embedded image

In the equation (1), m and n are 0,
1 or 2, R ¹ , R ² , R ³ and R ⁴ are a methyl group,
It is an ethyl group, an isopropyl group, an isoamyl group, a phenyl group or a hydrogen atom.

Further, the cationic polymerization initiator includes:
Preferably, at least one selected from the group consisting of an aromatic iodonium salt, an aromatic sulfonium salt and a metallocene salt, and an arylsilanol / aluminum complex is used.

The invention described in claim 4 is the first invention.
And heat-melting the reactive hot-melt adhesive composition according to any one of (1) to (3), applying the molten hot-melt adhesive composition to one or both of the adherends in a molten state, and irradiating the applied reactive hot-melt adhesive composition with light. After that, the adherends are attached to each other and pressure-bonded to each other. Hereinafter, details of the present invention will be described.

(Acrylic Copolymer) In the present invention, an acrylic copolymer of an alkyl acrylate having an alkyl group having 4 to 12 carbon atoms and a vinyl monomer is used. The structure of is not particularly limited, for example, a random copolymer structure,
Block copolymer structure, alternating copolymer structure, stereoregular structure, hyperbranched structure, star structure, dendritic structure, ladder structure,
Any structure such as a ring structure and a helical structure may be used.

If the alkyl group of the alkyl (meth) acrylate has more than 12 carbon atoms, the tackiness in the initial state at room temperature is undesirably reduced. Preferred examples of the acrylic copolymer include a polymer containing a unit composed of a (meth) acrylic ester in an acrylic polymer in an amount of 20% by weight or more. If the copolymerization ratio of the (meth) acrylate is less than 20% by weight, it may not be possible to obtain sufficient tackiness.

The method for producing the acrylic copolymer is not particularly limited, and includes radical polymerization, anionic polymerization,
Known appropriate methods such as coordination polymerization and photopolymerization can be used. However, preferably, the acrylic copolymer is obtained by subjecting a photopolymerizable composition containing an acrylic monomer to photoradical polymerization.

The alkyl (meth) acrylate monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate,
Examples thereof include 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isononyl (meth) acrylate, and isomyristyl (meth) acrylate.

The vinyl monomer is not particularly limited as long as it is a compound having an unsaturated bond copolymerizable with the alkyl (meth) acrylate monomer.
Examples include (meth) acrylonitrile, N-vinylpyrrolidone, isovoltanyl (meth) acrylate, N-acryloylmorpholine, benzyl (meth) acrylate, glycidyl (meth) acrylate, N-vinylcaprolactone, N-vinylpiperidine and the like. .

More preferably, the acrylic copolymer includes an alkyl (meth) acrylate monomer,
An acrylic copolymer obtained by subjecting a photopolymerizable composition containing a vinyl monomer and a photoradical polymerization initiator to photoradical polymerization is used.

(Cationically polymerizable compound) In the present invention, the above-mentioned cationically polymerizable compound is an organic compound having a portion that can be increased in molecular weight by cationic polymerization. The cationically polymerizable compound may be any of a monomer, an oligomer and a polymer, and may include carbon, hydrogen, oxygen,
It may contain organic compound constituent atoms such as nitrogen, sulfur and phosphorus.

The portion that can be made high molecular weight by cationic polymerization may be present at any of the terminal, side chain, and in the molecular skeleton of the molecular skeleton. Furthermore, the specific structure and molecular weight of the cationically polymerizable compound are not particularly limited.

The cationically polymerizable compound itself may be a hot-melt resin, and in that case, the hot-melt resin described below may not be used. In addition, the cationically polymerizable compound does not necessarily need to constitute the hot melt component in the hot melt adhesive composition according to the present invention, and may be a liquid compound at room temperature. Is mixed with the hot melt resin.

Specific examples of the cationic polymerizable compound include a cyclic ether compound (such as an epoxy compound, an oxetane compound, and an oxolane compound), a cyclic ester compound, and a vinyl ether compound. These cationically polymerizable compounds may be used alone or in combination of two or more.

The cationically polymerizable compound preferably comprises a compound having at least one structure represented by the formula (1) per molecule on average. Further, it is more preferable to use a compound having an average of two or more structures of the formula (1) per molecule.

As the cationically polymerizable compound, an epoxy compound is preferably used because of its excellent cationic polymerizability. Examples of the epoxy compound include an organic compound having at least one oxirane ring polymerizable by cationic polymerization, and may be a monomer, an oligomer, or a polymer, and may be any of aliphatic, alicyclic, and aromatic epoxy compounds. It may be a compound. The epoxy compound preferably has an average of 1 per molecule.
It has the above-mentioned epoxy group, and more preferably has an average of 2 or more epoxy groups per molecule.

The number of “average” per molecule of the structure of the formula (1) or the epoxy group is determined by the number of the structure of the formula (1) or the number of the epoxy group present in the compound. By the total number of compounds or epoxy molecules having the formula:

As the epoxy compound which is a polymer,
A linear polymer having a terminal epoxy group (for example, diglycidyl ether of polyoxyalkylene glycol), a polymer having an oxirane unit in its skeleton (for example, polybutadiene polyepoxide), and a polymer having an epoxy group in a side chain (glycidyl (meth) A) acrylate polymers or copolymers).

The molecular weight of the epoxy compound is not particularly limited, but may range from about 58 to about 100,000. Specific examples of the epoxy compound include, for example, aromatic epoxy resins such as bisphenol A type epoxy resin, alicyclic epoxy resins such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and Methylolpropane triglycidyl ether, 2,2-bis [4- (2,3
-Epoxypropoxy) cyclohexyl] propane, aliphatic epoxy resin, (meth) acrylate polymer or copolymer having an oxirane ring in the molecule such as glycidyl (meth) acrylate, epoxidized polybutadiene, and butadiene and other monomers And epoxidized copolymers of the above, modified products of these epoxy resins, and the like, but are not limited thereto. Further, the above epoxy compounds may be used alone or in combination of two or more.

(Cationic polymerization initiator) The cationic polymerization initiator is not particularly limited as long as it can generate a cation for initiating polymerization of the cationically polymerizable compound by light irradiation. Preferably, an aromatic iodonium salt, an aromatic sulfonium salt, and / or a metallocene salt, and an arylsilanol-aluminum complex are used. The aromatic iodonium salt and aromatic sulfonium salt effective as a cationic polymerization initiator,
For example, it is disclosed in U.S. Pat. No. 4,256,828. Further, regarding metallocene salts, US Pat.
No. 89,536. The amount of the cationic polymerization initiator varies depending on the type and intensity of light, the type and amount of the cationic polymerizable compound, the type of the cationic polymerization initiator, and the like, but is preferably 0.1 to 100 parts by weight of the cationic polymerizable compound. 01 to 10 parts by weight are blended.

(Softening Point by Ring and Ball Measurement) In the present invention, the softening point of the reactive hot melt adhesive composition by ring and ball measurement is in the range of 40 to 180 ° C.
Preferably 60 to 150C, more preferably 60 to 12C.
It is in the range of 0 ° C.

In the present specification, the softening point by the ring and ball measuring method is a value measured according to JIS K6863. If the softening point by the ring and ball measurement method is less than 40 ° C., the time for the adhesive to cool and solidify in the case of bead coating or the like becomes longer, and the bead shape is deformed or the next operation is performed immediately. Or a sufficient initial adhesive strength cannot be obtained. Further, if the softening point exceeds 180 ° C., the melt viscosity becomes extremely high, and the application work becomes difficult, or if the temperature is increased to facilitate the application, heat deterioration of the adhesive and burns of the worker are caused. Easy to cause.

(Other components that can be added) The reactive hot melt adhesive composition according to the present invention may contain a hydroxyl compound, if necessary. The hydroxyl compounds that can be used can be liquid or solid, but have at least one, and preferably at least two, hydroxyl groups. In this case, the hydroxyl group may be at the terminal of the compound or may be present in a side group of the polymer or copolymer.

Examples of the above-mentioned hydroxyl compound include, but are not limited to, alkylene glycol, polyhydroxyalkane, and polyoxyalkylene polyol. The hydroxyl compound may be added alone or in combination of two or more.

In the reactive hot melt adhesive composition according to the present invention, a hot melt type resin may be added as required. That is, when the cationically polymerizable compound itself is a hot-melt resin, it is not necessary to use another hot-melt resin, but another hot-melt resin may be added. When the reactive compound is not a hot melt resin,
A hot-melt resin is added to enable it to be used as a hot-melt adhesive.

As the hot melt resin, those having an appropriate molecular weight from low molecular weight to high molecular weight can be used. For example, tackifying resins such as styrene resin, petroleum resin and natural resin can be used. Resin, polyolefin resin such as ethylene-vinyl acetate copolymer resin, rubber resin such as butadiene-styrene block copolymer, acrylic copolymer resin, polyester resin or hot melt type thereof Various modified products of the resin can be exemplified, but not limited thereto, and two or more of these hot melt resins may be used in combination.

The reactive hot melt adhesive composition according to the present invention may further contain, if necessary, an adhesion improver (such as a silane coupling agent or a titanium coupling agent), a sensitizer, a dehydrating agent, Anti-aging agents, stabilizers, plasticizers, waxes, fillers, flame retardants, foaming agents, antistatic agents, fungicides,
Components such as a viscosity modifier can be added, but other components that can be added are not limited to the above components. Further, two or more kinds of the above-mentioned components may be added. In addition, these components may be added in advance during the production of the above-described hot melt resin, and such a case is also acceptable.

(Method for producing reactive hot melt adhesive)
As for the method for producing the reactive hot melt adhesive according to the present invention, any method may be adopted as long as the components to be blended can be mixed and uniformly dispersed, but appropriate heating may be employed so that the materials used can be melted. It is necessary to knead under conditions. Also,
The mixing and dispersion of each component at the time of production may be performed without a solvent or may be performed in an inert solvent. Specifically, it can be performed using one or more of a double helical ribbon bath or gate bath, a butterfly mixer, a planetary mixer, a three-roll, a kneader-ruder kneader or an extruder-type kneader extruder. However, the apparatus for kneading each component is not limited to these.

Regardless of the type of equipment used for mixing and dispersing the components, it is preferable to mix and disperse the components under anhydrous conditions because the amount of water, which is a component inhibiting cationic polymerization, is reduced.

When mixing and dispersing the components, the components are mixed and dispersed under atmospheric pressure or, if necessary, at or above atmospheric pressure or at or below atmospheric pressure. In addition, the order of adding each component at the time of production is not particularly limited, but in order to shorten the melting time or reduce the deterioration of the obtained composition, generally, it is difficult to melt, or at the time of melting. It is desirable to charge in order from the one that is hardly deteriorated by heat or mechanical shearing force.

In producing the reactive hot melt adhesive composition according to the present invention, it is necessary to carry out the production in a state where light effective for starting curing is blocked. The method for storing the reactive hot melt adhesive composition is not particularly limited as long as it can block light effective for initiating curing, but preferred storage containers include pale cans, tin cans, drums, and cartridges. , A release box, a release tray, a cardboard container, a paper bag, a plastic bag (for example, a composite film in which an aluminum foil is sandwiched), and a container opaque to light effective for initiating curing. However, it is not limited to these containers, and the material of these containers is not particularly limited as long as light can be blocked. Further, the reactive hot melt adhesive composition according to the present invention may be used immediately after production without being stored.

(Adhesion method) In the adhesion method according to the sixth aspect of the present invention, the reactive hot melt adhesive composition is heated and melted, and is applied to one or both of the adherends in a molten state. The reactive hot melt adhesive composition is irradiated with light, the adherends are adhered to each other, and bonded by pressing.

The method for applying the reactive hot melt adhesive composition by heating and melting is not particularly limited. For example, hot melt melted and heated by a usual hot melt applicator or hot melt coater is used. A method of applying the adhesive composition to an adherend,
A method of immersing an adherend in a hot-melt reactive hot-melt adhesive composition, a method of spraying a hot-melt adhesive composition being heated and melted on an adherend by a hot-melt air gun, an extruder, etc. And extruding the hot melt adhesive composition heated and melted on the surface of the adherend.

The hot melt adhesive composition may be supplied to the hot melt applicator using a pail unloader, a cartridge dispenser, or the like, and the hot melt adhesive composition may be applied in the form of a stick, pellet, slug, block, pillow, billet, or the like. The apparatus may be supplied with a hot melt adhesive composition.

As for the heating, the entire reactive hot melt adhesive composition may be heated and melted, or may be heated and melted only in the vicinity of the heating body. In any case of using any of the melt coating methods, it is desirable that the melt coating be performed in a state where light effective for starting curing is blocked.

As the light, any light can be used as long as a cation can be generated from the above-mentioned cationic polymerization initiator. The type of light is appropriately selected according to the type of the cationic polymerization initiator, and is preferably selected. UV light is used. Preferably, light having a wavelength of 200 to 600 nm is used. Particularly, when an aromatic iodonium salt, an aromatic sulfonium salt, or a metallocene salt is used as the cationic polymerization initiator, light having a wavelength of 200 to 400 nm is used. It is desirable to use.

The irradiation amount of the light also varies depending on the type of the cationic polymerization initiator and the thickness and the amount of the portion to which the reactive hot melt adhesive composition is applied. It is desirable to set it in the range of 0.001 J to 10 J.

When ultraviolet rays are used as the light source, those generally used as ultraviolet irradiation sources such as a fluorescent lamp and a high-pressure mercury lamp can be used. As for the method of irradiating the light, the hot melt adhesive may be directly irradiated, or a method of irradiating the hot melt adhesive with an effective amount of light through a transparent or translucent adherend may be employed. However, there is no particular limitation.

Regarding the method of laminating and pressing the adherends, a reactive hot melt adhesive composition is applied to one adherend, and then the other adherend is laminated, and necessary pressure and temperature are required. For example, a method of applying pressure for an appropriate time, a method of applying a reactive hot melt adhesive composition to both adherends, and applying pressure at an appropriate pressure and temperature for a necessary time can be exemplified.

The reactive hot melt adhesive composition according to the present invention can be sufficiently cured by the above-mentioned light irradiation under normal conditions. However, if the curing time is to be further shortened, it can be heated to an appropriate temperature. Good. In this case, the heating method cannot be uniquely determined because it differs depending on the type of the reactive hot melt adhesive composition, the shape and properties of the adherend, the heating conditions, and the like. A method of placing in a heated oven, a method of heating with a heater, and the like may be used, and two or more of these may be used in combination. However, the heating method is not limited to the above method. The heating temperature when shortening the curing time is preferably lower than the temperature at which the reactive hot melt adhesive composition itself softens. Otherwise, the softening of the composition may cause displacement of the bonded portion.

(Adherend to be Applied) The adherend to which the reactive hot melt adhesive composition according to the present invention is applied and the adherend to be used in the bonding method according to the present invention are particularly limited. Although not a thing, for example, metals or alloys such as iron and aluminum, plastics or plastic mixtures, inorganic materials such as glass, concrete, stone, mortar, and ceramics, cellulosic materials such as wood and paper, and a wide range of materials such as leather It can be applied to adherends. Also, regarding the shape of the adherend,
A rod, a sheet, a string, a fiber, a honeycomb, a tube, a particle, and the like may be used in any appropriate form, and it is also possible to use a different form for attaching an adherend.

(Use) The reactive hot melt adhesive composition according to the present invention is used as a reactive hot melt adhesive, particularly as an elastic adhesive, a structural adhesive, a pressure-sensitive adhesive, a sealing material, and the like. be able to. Such reactive hot melt adhesive composition, for example, door panels,
Adhesion of core and surface materials for sandwich panels such as partitions, shutters, furniture, blackboards, white boards, and panels for housing of office equipment, and core and surface materials for furniture, partitions, door panels and ceiling materials for automotive interior materials, etc. It is preferably used for applications such as bonding. However, the use of the reactive hot melt adhesive is not limited to the above use.

[0053] The reactive hot melt adhesive composition according to the invention described in the action claim 1-4, melted by heating, to soften, applying to an adherend in the same manner as normal hot-melt adhesive be able to. In addition, since the above-mentioned specific acrylic copolymer is used, it has tackiness at room temperature and can be easily bonded. Further, after application to the adherend, the cationic polymerization initiator generates cations by irradiating light, the cation polymerizable compound is polymerized by the cations,
As the curing proceeds with increasing the molecular weight, it is possible to obtain an adhesive cured product having excellent heat resistance, and since the adhesive cured product has almost no tackiness, the heat resistance of the adhesive cured product can be increased, and the adhesive cured product can be obtained. No dust or the like adheres to the surface.

Accordingly, since the curing is started only by the above-mentioned light irradiation, the reactive hot melt adhesive composition is applied to the adherend, and then the light is irradiated at the timing of the bonding, whereby the bonding is performed. It is possible to prevent the curing from proceeding before. That is, by setting the timing of light irradiation, the application time can be set to a sufficient length.

Further, since it has adhesiveness for a while after being irradiated with light, it can be used for work having a long open time such as a low-speed line or manual work. In the invention described in claim 2, the cationically polymerizable compound is composed of an epoxy compound having an average of one or more epoxy groups per molecule or a compound having an average of one or more structures of the formula (1) per molecule. Therefore, the above-described light irradiation rapidly causes ring-opening polymerization and cure. Therefore, the adherends can be firmly bonded to each other, and the heat resistance can be improved.

According to the third aspect of the present invention, an aromatic iodonium salt, an aromatic sulfonium salt and / or a metallocene salt, and an arylsilanol / aluminum complex are used as the cationic polymerization initiator.
By irradiating with light having a wavelength of nm, curing can proceed promptly and an adhesive having excellent storage stability can be obtained.

According to the fourth aspect of the present invention, the first to third aspects are provided.
After heating and melting the reactive hot melt adhesive composition according to any one of the above, it is applied in a molten state to one or both of the adherends, and the light is applied to the applied reactive hot melt adhesive composition. After the irradiation, the adherends are bonded together, and the bonding is performed by pressure bonding at room temperature or under heating.
By setting the timing after the application until the light irradiation, the application time can be extended. That is, by extending the time from application to irradiation with light, the application time can be extended, and the optimal application time can be set according to the application and the bonded portion.

In addition, since the curing of the reactive hot-melt adhesive composition proceeds only by light irradiation, the time required for the heat resistance to develop varies depending on ambient humidity and weather. Difficult to do.

[0059]

The present invention will be clarified by the following non-limiting examples.

Example 1 In a 500 ml bottle, 100 g of n-butyl acrylate, 100 g of cyclohexyl acrylate, 0.24 g of a photoradical polymerization initiator (manufactured by Ciba Geigy, product: Irgacure 651) and a chain transfer agent (1- 0.02 g of dodecanethiol) was added, and the bottle was wrapped with aluminum foil to prevent light from entering. Thereafter, bubbling was performed for 1 hour using nitrogen gas, and dissolved oxygen was removed while stirring the system to obtain a photopolymerizable composition.

Next, a polyethylene terephthalate (hereinafter, PET) film (manufactured by Toray Industries, Inc.) was placed on a smooth glass plate.
Product name: Lumirror, thickness 50 μm, inner surface of which has been subjected to mold release treatment) with the inner surface as the upper surface, a 3 mm-thick sealing tape stuck thereon to form a rectangular frame, and the photopolymerizable composition in the rectangular frame region A second PET film having the same rectangular frame region as above was prepared, and the rectangular region was sealed so that the inner surface of the PET film was in contact with the photopolymerizable composition surface. At this time, care was taken to prevent air bubbles from entering the photopolymerizable composition filled in the rectangular frame-shaped region. Then, using a fluorescent lamp (manufactured by Toshiba Lighting & Technology Corp., 20W chemical lamp, product number: FL20S / BL), 365 nm
Was irradiated for 40 minutes so as to have an intensity of 3.6 W / cm ² to obtain an acrylic copolymer.

Next, the PET film was peeled off, the acrylic copolymer was taken out, and the acrylic copolymer was obtained (this acrylic copolymer is referred to as acrylic copolymer 1 in the following table). And 50 g of a commercially available alicyclic epoxy resin (manufactured by Union Carbide Japan, trade name: E
RL4221) and 50 g of a cationic photopolymerization initiator (manufactured by Asahi Denka Co., Ltd., trade name: SP-170) were circulated through a heated oil and charged into a jacketed planetary mixer, and the whole was covered with aluminum foil. 30 r at 150 ° C
The mixture was mixed at pm for 60 minutes to obtain a hot melt adhesive composition.

Example 2 70 g of the acrylic copolymer 1 obtained in Example 1 and a commercially available alicyclic epoxy resin (trade name: ERL4221 manufactured by Union Carbide Japan Co., Ltd.)
Except that 30 g and 1 g of a cationic photopolymerization initiator (manufactured by Asahi Denka Co., trade name: SP-170) were blended,
A reactive hot melt adhesive was obtained in the same manner as in Example 1.

Example 3 As an epoxy resin, bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd.)
Reactive hot melt adhesion in the same manner as in Example 2 except that 30 g of trade name: Epicoat 828) and 3 g of a cationic photopolymerization initiator (trade name: SP-170, manufactured by Asahi Denka Co., Ltd.) were used. Agent was obtained.

Comparative Example 1 A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was charged with 42 parts by weight of ethyl acetate, 8 parts by weight of isopropyl alcohol,
47 parts by weight of butyl acrylate, 50 parts by weight of 2-ethylhexyl acrylate, 3 parts by weight of a vinyl monomer having a cyclohexene monoepoxide group (manufactured by Daicel Chemical Industries, part number: M-100), and a polymerization initiator (manufactured by NOF Corporation) 0.02 parts by weight of Niper BMT-K40), and reacted under reflux in a nitrogen atmosphere for 4 hours. Then, a solution of azobisisobutyronitrile in ethyl acetate (azobisisobutyronitrile) was further added. (A mixed solution of 0.1 parts by weight and 5 parts by weight of ethyl acetate) was dropped in three portions every hour and aged for 2 hours to obtain an acrylic copolymer solution having a weight average molecular weight of 230,000. This is referred to as acrylic copolymer 2.

To 100 parts by weight of the acrylic copolymer 2, 0.3 part by weight of a compound having two or more hydroxyl groups per molecule (manufactured by Union Carbide Co., trade name: Tone polyol 0301) was added. Cationic polymerization initiator (manufactured by Union Carbide, trade name: CYRACUR)
After adding 0.2 parts by weight of EUVI-6970) and stirring and mixing, the mixture was heated and the solvent was removed to obtain a hot melt adhesive.

(Evaluation of Examples and Comparative Examples) Using the respective reactive hot melt compositions obtained in Examples and Comparative Examples, adhesive properties, initial adhesive strength and heat resistant adhesive strength were evaluated in the following manner. The results are shown in Table 1 below together with the measurement results of the softening point by the following ring and ball measurement method.

Softening point by ring and ball method: The obtained reactive hot melt adhesive and reactive hot melt pressure sensitive adhesive were measured for softening point by ring and ball method according to JIS K6863.

Adhesive property: Each reactive hot melt composition was applied on a PET film to a thickness of 30 μm using a roll coater set at 150 ° C. This was used as a test piece before light irradiation. An illuminance of 25 mW was applied to the applied reactive hot melt composition using a high-pressure mercury lamp “Jetlight JL2300” manufactured by ORK Seisakusho.
/ Cm ² was irradiated with light having a wavelength of 365 nm for 4 seconds, and the release paper was bonded. This was cured at 23 ° C. and a relative humidity of 60% for 7 days to obtain a test piece after light irradiation and curing. Using each of the test pieces, the adhesive properties were evaluated according to JIS Z0237 (ball tack test method).

Initial adhesive strength: Using a roll coater set at 150 ° C., the reactive hot melt adhesive composition was applied to a 25 mm × 125 mm × 1.6 mm SPCC dull steel plate at a thickness of 50 to 150 μm. . Thereafter, the applied reactive hot melt adhesive composition was added with OR
High-pressure mercury lamp "Jetlight JL230" manufactured by K Seisakusho
0 ”and 36 so that the illuminance is 25 mW / cm ^2.
Irradiate light of 5 nm wavelength for 4 seconds, and furthermore, 25 mm x
Overlay a 125mm # 9 cotton canvas at 100 ° C for 2 minutes,
After applying a pressure of 0.5 kg / cm ^{2 and} hot pressing,
A pressure of 0.5 kg / cm ² was applied at 23 ° C. for 2 minutes and subjected to cooling press to produce an adhesion test piece under the conditions shown in Table 1 without curing. Immediately after producing this adhesive test piece, JIS
The floating roller method peel test was performed at 23 ° C. according to K 6854, and the peel strength was measured, and the result was taken as the initial adhesive strength without curing. In addition, the adhesive test specimen was cured at 23 ° C. and a relative humidity of 60% for 7 days, and then the initial adhesive strength was measured under the post-curing condition.

Heat resistant adhesive strength: JIS K6 in the same manner as the adhesive test specimen prepared for the evaluation of the initial adhesive strength.
A floating roller method peel test was performed at 100 ° C. in accordance with 854, and the peel strength was measured, which was taken as the heat-resistant adhesive strength.

[0072]

[Table 1]

As is evident from Table 1, the reactive hot melt pressure-sensitive adhesive of Comparative Example had a low softening point according to a ring and ball measurement method, so that when a bead was applied to a vertical surface, the bead dropped and the workability was poor. In the reactive hot melt pressure-sensitive adhesive of Comparative Example, the ball tack value of the cured product was 6, and the cured product was cured for 7 days. The obtained reactive hot melt adhesive did not show tackiness. Therefore, in the hot melt adhesives of Examples 1 to 3, it is found that dust and the like hardly adhere to the cured adhesive and hardly cause contamination.

The hot melt pressure-sensitive adhesive of Comparative Example 1 may have a heat-resistant adhesive strength of 23
When cured for 7 days at 60 ° C. and 60% relative humidity, the adhesive strength does not increase as much as 1.0 kgf / 25 mm, whereas the hot melt adhesives of Examples 1 to 3 show excellent results in the evaluation of heat resistant adhesive strength. Indicated. That is, it can be seen that since it has almost no tackiness, the heat-resistant adhesiveness is enhanced.

[0075]

The reactive hot-melt adhesive composition according to the first to third aspects of the present invention can be easily applied by heating and melting similarly to a conventional hot-melt adhesive, and can be initially formed at room temperature. In the state, since it has adhesiveness, the bonding operation can be easily performed, and a complicated operation such as temporary fixing can be omitted. Because the cationically polymerizable compound is cured by increasing the molecular weight, the heat resistance of the adhesive cured product is increased,
Furthermore, since the cured adhesive has little tackiness,
The heat resistance of the final cured product is less likely to be reduced due to the tackiness, and the contamination due to adhesion of dust to the cured adhesive product is also less likely to occur.

In the bonding method according to the present invention, after the reactive hot melt adhesive composition according to the present invention is heated and melted,
To be applied to at least one of the adherends in a molten state, to adhere the adherends after irradiating the applied reactive hot melt adhesive composition with light, to press-bond at room temperature or under heating, By adjusting the time from the application to the irradiation of light, the application time can be easily controlled according to the type of the adherend and the adhesive part, and furthermore, it has almost tackiness in the initial state. Therefore, the adherends can be stuck to each other with certainty, and an adhesive cured product having excellent heat resistance can be provided. Furthermore, since it has adhesiveness for a while after being irradiated with light, it can be suitably used for work having a long open time such as a low-speed line or manual work.

Claims (4)

[Claims] An acrylic copolymer of an alkyl (meth) acrylate having an alkyl group having 4 to 12 carbon atoms and a vinyl monomer, a cationically polymerizable compound, and a method for curing a cationically polymerizable compound by irradiation with light. Having a softening point of 4 as determined by ring and ball measurement
A reactive hot melt adhesive composition, which is in the range of 0 to 180 ° C. 2. The method according to claim 1, wherein the cationically polymerizable compound is a compound having a structure of the following formula (1) having an average of one or more per molecule or an epoxy compound having an average of one or more epoxy groups per molecule. Reactive hot melt adhesive composition. Embedded image In the formula (1), m and n are 0, 1 or 2,
R ¹ , R ² , R ³ and R ⁴ are a methyl group, an ethyl group, an isopropyl group, an isoamyl group, a phenyl group or a hydrogen atom. 3. The method according to claim 1, wherein the cationic polymerization initiator comprises an aromatic iodonium salt, an aromatic sulfonium salt, and a metallocene salt.
The reactive hot melt adhesive composition according to claim 1 or 2, wherein the composition is at least one selected from the group consisting of arylsilanol / aluminum complexes. 4. The reactive hot melt adhesive composition according to claim 1, which is heated and melted and applied to one or both of the adherends in a molten state, and the applied reactive hot melt is applied. A bonding method comprising irradiating the adhesive composition with light, bonding the adherends together, and pressing the adherend.