JP2003193023A - Reactive hot melt adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a reactive hot melt adhesive having curing reactivity promotable by photoirradiation, exhibiting excellent adhesive strength and having excellent thermoresistant adhesiveness. <P>SOLUTION: The subject reactive hot melt adhesive composition comprises a solid cationically polymerizable compound A having, per one molecule, on the average, at least one cationically polymerizable reactive group having a structure of formula (1) (wherein, R<SB>1</SB>, R<SB>2</SB>, R<SB>3</SB>and R<SB>4</SB>are each H, methyl, ethyl, isopropyl, isoamyl or phenyl; (m) and (n) are 0, 1 or 2), a cationically polymerizable compound B having, per one molecule, at least one alkylene oxide and, on the average, two or more cationically polymerizable reactive group having a structure of formula (1) and a photo-cationic polymerization initiator. <P>COPYRIGHT: (C)2003,JPO

Description

Description: 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 by irradiation of light. [0002] In various applications, paper, fiber, wood,
Hot melt adhesives are widely used for bonding glass, plastic or metal. When using 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. In a molten state, a hot melt adhesive is applied to the adherends, and the adherends are adhered to each other by cooling and solidification. The time from the bonding of the adherends to the development of the bonding strength is very short, usually within 1 minute, so that the bonding operation can be performed in a very short time. However, hot-melt adhesives have a drawback that they generally have insufficient heat resistance because they need to be heated and melted. Therefore, various methods have been attempted to improve the heat resistance by introducing a curing system by some kind of chemical reaction at the time of applying and bonding the hot melt adhesive. For example, JP-A-49-98445 discloses a moisture-curable hot melt adhesive. However, since the curing reaction proceeds due to moisture in the air, the storage stability is poor, the curing reaction is slow, and furthermore, the curing is insufficient with the moisture-impermeable material, or the work is carried out because it contains an isocyanate compound. Various problems that the environment deteriorates have been pointed out. On the other hand, with adhesives other than hot melt adhesives, as a curing system instead of a moisture curing type, curing of an epoxy compound is performed by using a cationic photopolymerization initiator which decomposes by light to generate a Lewis acid. The use of an intended curing system is being considered. Various adhesive compositions using such a curing system have been proposed. For example, JP-B-3-30633 discloses a bisphenol type external /
Also disclosed is an adhesive comprising a novolak type epoxy compound, a liquid alicyclic epoxy compound, and a cationic photopolymerization initiator. Further, Japanese Patent No. 2684053 discloses a method for producing an abrasive in which an epoxy resin containing a cationic photopolymerization initiator is applied to an adhesive layer of abrasive particles. However, the adhesives disclosed in these prior arts are not hot melt adhesives. [0006] If a curing system using the above epoxy compound and a cationic photopolymerization initiator is introduced into a hot melt adhesive, a photocurable hot melt adhesive can be obtained. In addition, the cured product can be cured by irradiation with light to increase the heat resistance of the cured product. However, in a hot-melt adhesive composition incorporating such a curing system, shrinkage during curing causes internal strain in the cured product, resulting in poor adhesion between the adherend and the adhesive, and sufficient adhesive strength. It turned out that it could not be obtained. SUMMARY OF THE INVENTION In view of the above-mentioned state of the art, the object of the present invention is to provide a curing reaction which proceeds by irradiation with light, and has excellent heat resistance of an adhesive and excellent adhesiveness to an adherend. It is to provide a melt adhesive. According to a broad aspect of the present invention, a solid cationically polymerizable compound having an average of one or more cationically polymerizable reactive groups having the structure of the following formula (1) per molecule: A compound A, a cationic polymerizable compound B having at least one alkylene oxide per molecule in the molecule, and having an average of two or more cationic polymerization reactive groups having the structure of the following formula (1); And a reactive hot-melt adhesive composition, comprising: [0009] The reactive hot melt adhesive composition of the present invention melts and softens when heated, and can be applied to an adherend in the same manner as a normal hot melt adhesive. In addition, since the cationic polymerization reactive group in the cationically polymerizable compound reacts upon irradiation with light, application or film formation on an adherend at a relatively low temperature, and high heat resistance after laminating and curing are compatible. It is possible to do. Further, since the cationically polymerizable compound B having at least one alkylene oxide in the molecule is used in combination with the solid cationically polymerizable compound A, internal strain due to shrinkage during curing is absorbed and absorbed. Therefore, the adhesion to the adherend is improved, and the adhesion is enhanced. Hereinafter, the present invention will be described in detail. The solid cationically polymerizable compound A used in the present invention is not particularly limited as long as it is a solid compound having an average of one or more cationically polymerizable groups having the structure of the above formula (1) in the molecule.
It may be a monomer, oligomer or polymer.
Further, carbon, hydrogen, oxygen, nitrogen, sulfur, or a phosphorus atom may be included as a constituent atom, and the cationic polymerization reactive group may be present at a terminal of the molecular skeleton, and may be present as a side chain. May be present in the molecular skeleton, and the structure and molecular weight of the cationically polymerizable compound A are not particularly limited. In addition, cationic polymerizable compound A
May itself be a hot melt resin. More specifically, the cationically polymerizable compound A is, for example, a cyclic ether compound such as a solid epoxy compound, a solid oxetane compound or a solid oxolane compound. Are suitably used. Examples of the solid epoxy compound include a solid bisphenol A epoxy resin, a solid bisphenol F epoxy resin, and a solid novolak epoxy resin. The above-mentioned cationically polymerizable compounds may be used alone or in combination of two or more. The cationically polymerizable compound B used in the present invention has at least one alkylene oxide in the molecule, and has the following formula (1)
The compound is not particularly limited as long as it is a compound having an average of two or more cationic polymerization reactive groups having the structure of, and may be a monomer, oligomer, or polymer, and includes carbon, hydrogen, oxygen, nitrogen, sulfur, a phosphorus atom, or the like as a constituent atom. May be included, the cationic polymerization reactive group may have at the terminal of the molecular skeleton,
It may have it as a side chain or may have it in a molecular skeleton, and its structure and molecular weight are not limited. The cationically polymerizable compound B may itself be a hot melt resin. Examples of the cationic polymerizable compound B include, for example, epoxy compounds, oxetane compounds, and cyclic ether compounds such as oxolane compounds. Among them, epoxy compounds are preferably used because of their excellent cationic polymerizability. For example, a diglycidyl compound of polyoxyethylene or polyoxypropylene, a diglycidyl compound of a polyol obtained by adding ethylene oxide or propylene oxide to bisphenol A or bisphenol F, and the like can be mentioned. Further, two or more of these cationically polymerizable compounds may be used in combination. By using such a cationically polymerizable compound B in combination with the solid cationically polymerizable compound A, internal strain due to shrinkage during curing is relaxed and absorbed, adhesion to an adherend is improved, and adhesion is enhanced. . The compounding ratio of the cationic polymerizable compound B to the solid cationic polymerizable compound A is 1/99 to 5 by weight.
A range of 0/50 is preferred. When the ratio is less than 1/99, the adhesiveness to the adherend is insufficient, and when it exceeds 50/50, the tack becomes excessive, and the hot melt adhesive applied to the adherend in a molten state is separated from another. When the laminating position is bad in the step of laminating to the adherend, the lamination is not possible and the lamination cannot be performed again. The cationic photopolymerization initiator C used in the present invention is not particularly limited as long as it can generate a cation for initiating polymerization of the cationically polymerizable compound by light irradiation. Examples thereof include an aromatic iodonium salt, an aromatic sulfonium salt, a metallocene salt, and an arylsilanol / aluminum complex. These photocationic polymerization initiators, for example, aromatic iodonium salts and aromatic sulfonium salts are disclosed in US Pat. No. 4,256,828. The metallocene salt is disclosed in US Pat. No. 5,089,536. By using these photocationic polymerization initiators, curing can be rapidly progressed by irradiation with light having a wavelength of 200 to 400 nm,
An excellent heat-resistant adhesive strength can be exhibited. Further, if the light is blocked, no curing reaction occurs, so that the adhesive has excellent storage stability. The amount of the cationic photopolymerization 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.
It is blended at a ratio of 0.01 to 10 parts by weight with respect to 0 parts by weight. In the present invention, it is essential that the composition obtained by uniformly mixing and dispersing the above-mentioned solid cationically polymerizable compound A, cationically polymerizable compound B, and cationic photopolymerization initiator C is solid at 20 ° C. . If necessary, a thermoplastic resin may be added to the reactive hot melt adhesive composition.
The thermoplastic resin is not particularly limited as long as it is a resin that is melted by heating and solidified by cooling. For example, polyolefin such as polyethylene and polypropylene; polybutadiene; polychloroprene; polyisoprene; styrene-butadiene copolymer; acrylonitrile- Elastomer resins such as butadiene copolymer; polyether resins such as polyethylene oxide, polypropylene oxide, and polytetramethylene oxide; polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, ethylene-vinyl chloride copolymer, poly Vinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer,
Polyvinyl resins such as polyvinyl formal, polyvinyl butyral, and polyvinyl ether; (meth) acrylic copolymer resin; styrene resin; polyester; polycarbonate; ketone resin; acrylonitrile-styrene copolymer resin; acrylonitrile-butadiene-styrene copolymer resin. And the like. 20 ° C of the above resin
In the above, a solid material is preferably used because the heat resistance of the adhesive after the photocation polymerization reaction is easily developed, and specifically, polyvinyl resins, (meth) acrylic copolymer resins, polyesters, and polycarbonates are preferable. Used for These resins may be used alone or in combination of two or more. The mixing ratio of the thermoplastic resin to the total of the solid cationically polymerizable compound A and the cationically polymerizable compound B is preferably in the range of 95/5 to 5/95 by weight, and particularly preferably 10/95. 90-80 / 20. The reactive hot-melt adhesive composition may further include, if necessary, an adhesion improver such as a silane coupling agent and a titanium coupling agent; a sensitizer, a dehydrating agent, an antioxidant, and a stabilizer. , Plasticizers, waxes, fillers, flame retardants, foaming agents, antistatic agents, antifungal agents, viscosity modifiers and other components can also be added, but those that can be added are not limited to these components Absent. Two or more of these components may be used in combination. These components may be added to the above-described components in advance, or may be added later. As a method for producing the reactive hot melt adhesive composition of the present invention, any method may be adopted as long as the components to be blended can be mixed and uniformly dispersed. It is necessary to produce under moderate heating conditions. In addition, the components may be mixed and dispersed at the time of production without solvent, or may be mixed in an inert solvent and then desolventized. Specific kneading equipment includes double helical ribbon bath, gate bath, butterfly mixer, planetary mixer, three rolls, kneader-ruder type kneader,
Examples thereof include an extruder-type kneading extruder, but are not limited thereto. Each of the above production methods is preferably carried out under anhydrous conditions in order to reduce the incorporation of water which is a component inhibiting cationic polymerization. In addition, any of the production methods is carried out under atmospheric pressure or, if necessary, above atmospheric pressure or below atmospheric pressure. Also, in any case of the adhesive manufacturing method, it is necessary to perform the method in a state where light effective for starting curing is substantially blocked. Also, as the heating temperature range during manufacturing,
The temperature is preferably from 50 to 250C, more preferably from 80 to 200C. Also, two or more of these production methods may be used in combination. The composition thus produced may be tacky or non-tacky. In the above reactive hot melt adhesive composition, the reaction proceeds by light irradiation, and the storage is not particularly limited as long as it can block light including light effective for starting curing. Preferred storage containers include pail cans, tin cans, drums, cartridges, release boxes,
Examples include, but are not limited to, containers that are opaque to light effective to initiate curing, such as release trays, cardboard, paper bags, plastics, and the like. The material of these containers is not limited. Further, the reactive hot melt adhesive composition according to the present invention may be used immediately after production without employing these storage methods. The method for bonding the adherend using the reactive hot melt adhesive composition is not particularly limited. For example, the reactive hot melt adhesive composition is heated and melted before the adherend is adhered. A method in which the applied reactive hot melt adhesive composition is irradiated with light and then bonded to an adherend, and then bonded by pressure bonding or heat pressing. From the reactive hot melt adhesive composition thus obtained, a film is formed by a roll coater, a flow coater, a bar coater, etc., and the adherend is irradiated with light after irradiating the obtained film-form reactive hot melt adhesive composition with light. Examples include a method of bonding by bonding, pressing or heat pressing. In the case of using a material that transmits light as the adherend, a method of irradiating light after bonding the adherend or pressing the adherend may be employed. As a method of applying the reactive hot melt adhesive composition to the adherend by heating and melting, there are a method of applying the composition heated and melted by an ordinary hot melt applicator or a hot melt coater to the adherend, A method of immersing an adherend in a composition that is heated and melted, a method of spraying a composition heated and melted by a hot melt air gun onto an adherend, a method of extruding a composition heated and melted by an extruder or the like to an adherend, But are not limited to these. The reactive hot melt adhesive composition may be sent to a hot melt applicator using a pail unloader, a cartridge dispenser, or the like, or may be a stick, pellet, slug, block, pillow, billet, or the like. May be sent to each of the above coating devices. When heating, the entire composition may be heated and melted, or only the vicinity of the heating body may be heated and melted. In any case of the melt coating method, it is necessary to perform the method in a state where light effective for starting curing is blocked. As the light used in the present invention, any light can be used as long as a cation can be generated from the above-mentioned cationic polymerization initiator, and the type of light is appropriately determined according to the type of the cationic polymerization initiator. UV radiation is selected and preferably used. Preferably, light having a wavelength of 200 to 600 nm is used. In particular, when an aromatic iodonium salt, an aromatic sulfonium salt, a metallocene salt, or the like is used as the cationic photopolymerization initiator, 200 to 400 nm is used.
It is desirable to use light having a wavelength of The method for irradiating light is not particularly limited as long as the method irradiates an effective amount of light directly or through a transparent or translucent adherend. The amount of light irradiation cannot be determined uniquely because it varies depending on the type of the cationic polymerization initiator and the thickness and amount of the portion to which the reactive hot melt adhesive composition is applied. It is desirable to be in the range of 0.001 J to 10 J. Since it is cured with low irradiation energy, if the thickness of the hot melt adhesive is about 200 μm, 60 m
A value of J or more is sufficient. When an ultraviolet ray is used as the irradiation source, a fluorescent lamp, a high-pressure mercury lamp, and the like, which are generally used as the irradiation source of the ultraviolet ray, are exemplified. The reactive hot-melt adhesive composition of the present invention can be sufficiently cured by being irradiated with light. However, if it is desired to further shorten the curing time, appropriate heating is performed during or after light irradiation. You can also. The heating method in this case, the type of the composition, the shape and properties of the adherend, the heating conditions, and may be appropriately optimized according to, for example, a method of blowing hot air, a method of placing in a heated oven, Examples include a method of heating with a heater, but the method is not limited thereto. The heating temperature for shortening the curing time is preferably lower than the temperature at which the reactive hot melt adhesive composition itself softens. Otherwise, the reactive hot-melt adhesive composition may be softened to cause a displacement of the bonded portion. Two or more of these curing methods may be used in combination. The adherend to be bonded using the reactive hot melt adhesive composition of the present invention is preferably PET. Furthermore, as other things, metals (iron, aluminum, etc.) and their alloys, plastics other than PET and their mixtures, inorganic materials (glass, concrete, stone, mortar, ceramics, etc.), cellulose materials (wood, paper, etc.), Leather, etc. are also exemplified,
It is not limited to these. Also, these adherends can be in the form of plates, chunks, rods, sheets, strings, fibers, honeycombs, tubes, particles, and other various forms. Further, the reactive hot melt adhesive composition according to the present invention may be used for laminating these different adherends. The reactive hot melt adhesive composition according to the present invention can be used as an elastic adhesive, a structural adhesive, a pressure-sensitive adhesive, a sealing material, and the like. Particularly suitable applications include uses of PET as an adherend, such as adhesion of cards made of PET film and adhesion of a molded product of PET. In addition, adhesion of core materials and surface materials of sandwich panels such as door panels, partitions, shutters, furniture, blackboards, white boards, and office equipment housing panels, furniture, partitions, door panels and ceiling materials for automotive interior materials, etc. It is preferably used for applications such as adhesion between a core material and a surface material, but is not limited to these applications. Hereinafter, the present invention will be described in more detail by giving non-limiting examples of the present invention. (Example 1) Preparation of composition A solid bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., trade name: Epicoat 1001) 85 parts by weight and a polyglycolyl diglycidyl compound (propylene oxide in the molecule) An average of about 3 components, 15 parts by weight of Nagase Kasei Co., Ltd., trade name: Denacol EX-920) and a cationic photopolymerization initiator (manufactured by Union Carbide Co., Ltd.)
(Product name: UVI-6990) was kneaded at 150 ° C. with a jacketed planetary mixer capable of circulating heated oil to obtain a reactive hot melt adhesive composition. Preparation of Composite Sheet The reactive hot-melt adhesive composition obtained as described above was treated at a temperature of 120 ° C. with a white PET having a thickness of 0.1 mm.
(Polyethylene terephthalate) coated on a sheet (trade name: Lumirror E20, manufactured by Toray Industries, Inc.), and then irradiated with ultraviolet light at an intensity of 1500 mJ / cm ² for 60 seconds using an ultra-high pressure mercury lamp to form a reactive hot melt adhesive composition. White P which is not coated with the reactive hot melt adhesive composition
An ET sheet (Lumirror E20) was laminated and thermally laminated at a temperature of 70 ° C. to obtain a composite sheet. Example 2 Preparation of Composition A diglycidyl compound of a bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., trade name: Epicoat 1001) of 80 parts by weight and a polyol obtained by adding ethylene oxide to bisphenol A (Contains an average of about 6 ethylene oxides in the molecule, manufactured by Nippon Rika Co., Ltd., trade name: B
EO-60E) and 20 parts by weight of a cationic photopolymerization initiator (manufactured by Union Carbide, trade name: UVI-699)
0) The composition consisting of 1 part by weight was mixed with a jacketed planetary mixer capable of circulating heated oil for 15 minutes.
The mixture was kneaded at 0 ° C. to obtain a reactive hot melt adhesive composition. Preparation of Composite Sheet A composite sheet was obtained in the same manner as in Example 1 using the reactive hot melt adhesive composition obtained as described above. Comparative Example 1 Preparation of Composition 100 parts by weight of a bisphenol A type epoxy resin (trade name: Epicoat 1001 manufactured by Yuka Shell Epoxy Co.)
A composition comprising 1 part by weight of a photocationic polymerization initiator (trade name: UVI-6990, manufactured by Union Carbide Co.)
The mixture was kneaded at 150 ° C. with a planetary mixer equipped with a jacket capable of circulating the heated oil to obtain a reactive hot melt adhesive composition. Preparation of Composite Sheet A composite sheet was obtained in the same manner as in Example 1 using the reactive hot melt adhesive composition obtained as described above. (Evaluation of Examples and Comparative Examples) Examples 1 and 2
Each composite sheet obtained in Comparative Example 1 was evaluated in the following manner. The results are shown in Table 1 below. Normal adhesiveness: The obtained composite sheet was subjected to a T-type peeling test using a tensile tester at 23 ° C. and a peeling speed of 50 mm / min, and the adhesive strength was measured. At the time of this measurement, the form of destruction was observed. In the case where the fracture mode was the material failure of the PET sheet, the strength at the time of material failure was taken, and in other cases, the average value of the adhesive strength was taken as the adhesive strength. Heat Resistance Adhesion: Each of the obtained composite sheets was subjected to a T-type peel test at a temperature of 80 ° C. at a peel rate of 50 mm / min using a tensile tester to measure the adhesive strength. In the measurement, the fracture mode was observed, and when the PET sheet was broken, the strength at that time was used, and in other cases, the average value of the adhesive strength was used as the adhesive strength. [Table 1] The reactive hot melt adhesive composition according to the present invention comprises a solid cationically polymerizable compound A, a cationically polymerizable compound B having at least one alkylene oxide in the molecule, Since it is composed of a polymerization initiator, the adhesiveness to an adherend is excellent, and a curing reaction proceeds by light irradiation, and excellent adhesive strength is exhibited. Furthermore, since the cationically polymerizable compound B having at least one alkylene oxide in the molecule and the solid cationically polymerizable compound A are used in combination as described above, the adhesiveness is excellent in heat resistance. Thus, according to the present invention, there is provided a hot-melt adhesive which can be easily applied by heat-melt coating, and which exhibits excellent adhesive strength after curing and has excellent heat-resistant adhesiveness. It is possible to provide a melt adhesive composition.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Masanori Matsuda             1259 Izumi, Minakuchi-cho, Koka-gun, Shiga Sekisui Chemical             Inside the company F-term (reference) 4J040 EC061 EC071 EC42 EE021                       HD18 HD31 HD33 HD43 JB01                       JB08 KA13 LA06 LA08

Claims (1)

Claims: 1. A solid cationically polymerizable compound A having an average of at least one cationically polymerizable reactive group having a structure of the following formula (1) per molecule, and an alkylene oxide per molecule. A cationically polymerizable compound B having at least one or more in the molecule and having an average of two or more cationically polymerizable groups having the structure of the following formula (1); and a cationic photopolymerization initiator C. Reactive hot melt adhesive composition. Embedded image