JP2011225668A - Expandable adhesive and expandable adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expandable adhesive and an expandable adhesive tape having both of adhering property and expanding property, which do not require accurate shaping in accordance with a shape of a member as an object of adhesion, nor require highly accurate positioning when used.SOLUTION: The expandable adhesive expands by application of stimulant such as light and heat, and fills a space between members and adheres the members to each other. The expandable adhesive tape has an expandable layer comprising the expandable resin composition, which expands by application of stimulant and fills a space between members, and the tape adheres the members to each other.

Description

  The present invention relates to an expandable adhesive and an expandable adhesive tape that perform bonding while expanding themselves in a gap between members.

  Conventionally, for example, in a portable image display device, a gap is provided between the image display panel and the transparent front plate for protecting the image display panel, and an impact absorbing sheet is disposed in the gap. The impact absorbing sheet is made of a rubber foaming agent that has been previously foamed. An example of such a structure is disclosed in Patent Document 1 below, for example. In Patent Document 1, the impact absorbing sheet prevents an external impact force from directly acting on the image display panel. Further, it is supposed that dust can be prevented from entering or generated from the external environment or internal members, thereby preventing visibility from being lowered.

  On the other hand, Patent Document 2 discloses a structure in which a lens unit of a camera is pressed against a front cover via an elastic body such as a foam cushion material. That is, the elastic body functions as a seal member between the lens unit and the front cover. For example, in the field of cameras, Patent Document 2 discloses that an elastic body such as a foam cushion material is used to press a lens unit against a front cover and to function as a seal member.

JP 2006-110773 A JP 2006-30419 A

  Since the impact-absorbing sheet described in Patent Document 1 is made of a foamed rubber-based foam in advance, it is necessary to accurately prepare the foam in advance in order to increase its sealing performance. Further, when a foamed rubber-based foam is used in advance, the shape of the foam required for each image display device is different, and therefore it is necessary to prepare many types of foamed molded articles. Furthermore, when manufacturing the image display device, it is necessary to increase the positioning accuracy of the foamed molded product in the gap with high accuracy.

  Moreover, the adhesion layer is provided in the surface of the impact-absorbing sheet described in Patent Document 1. Therefore, after obtaining the rubber-based foam, an adhesive layer must be further provided on the surface of the rubber-based foam.

  Since the elastic body described in Patent Document 2 is also made of a foam material that has been foamed in advance, the shape of the elastic body must be accurately adjusted, as in Patent Document 1. In addition, many types of elastic bodies must be prepared for each product. Furthermore, the elastic body must be accurately positioned when manufacturing the camera.

  It is an object of the present invention to eliminate the need to accurately adjust the shape according to the shape of the member to be bonded, and to eliminate the need for highly accurate positioning during use. It is to provide an adhesive tape.

  According to a wide aspect of the present invention, an expandable adhesive that fills a gap between members by being expanded by applying a stimulus and bonds the members to each other is provided.

  Expansion means, for example, that gas is generated in the expandable adhesive and the volume of the expandable adhesive is increased under the same external pressure by enclosing the gas in the resin.

  The expansion is performed by generating a gas when the cohesive force of the expandable adhesive is small or the crosslinking is not progressing.

  The gas is generated, for example, by applying a stimulus such as UV or heat in which a gas generating agent is contained in the expandable adhesive.

  In the present invention, preferably, the expandable adhesive fixes the shape after expansion and bonds the member to the member. In this case, since the shape after expansion is fixed, adhesion between the member and the member can be achieved, and the gap between the member and the member can be filled more reliably.

In a specific aspect of the expandable adhesive according to the present invention, the adhesive strength is in the range of 200 to 600 N / 4 cm ² . If the adhesive strength is 200 N / 4 cm ² or less, the adhesive strength is insufficient.

  In the present specification, the adhesive strength is a shearing adhesive force when an expandable adhesive is bonded using an adherend as a SUS plate and peeled off at a speed of 300 mm / min in the shearing direction.

  In another aspect of the expandable adhesive according to the present invention, it contains 100 parts by weight of an adhesive resin and 5 to 50 parts by weight of an expander that generates gas by stimulation. If the expansion agent which generates gas by stimulation is 5 parts by weight or less, expansion due to application of stimulation is insufficient, and it becomes difficult to fill the gaps between the members.

  In still another specific aspect of the expandable adhesive according to the present invention, the degree of crosslinking before expansion is 50% or less. When the degree of crosslinking before expansion is 50% or less, the volume of the expandable adhesive becomes sufficiently large due to expansion. Therefore, the gap between the members can be more reliably sealed.

  In still another specific aspect of the expandable adhesive according to the present invention, tan δ after expansion and curing is 0.5 or more and 1.0 or less at 25 ° C. In this case, it is easily deformed when an external force is applied, and the shock absorbing performance can be enhanced.

  The expansible adhesive tape which concerns on this invention is an expansible adhesive tape which fills the clearance gap between members by expanding by provision of irritation | stimulation, and adhere | attaches a member and a member.

  Preferably, the expansion layer fixes the shape after expansion and bonds the members to each other. In this case, since the shape after expansion is fixed, the gap between the member and the member can be more reliably sealed while bonding the member and the member.

  On the specific situation with the expandable adhesive tape which concerns on this invention, adhesive force exists in the range of 2-20N / 25mm. If the adhesive strength is within this range, the members can be more reliably bonded together, and the gap between the members can be more reliably sealed.

  In a specific aspect of the expandable adhesive tape according to the present invention, the expandable resin composition contains 100 parts by weight of the adhesive resin and 5 to 50 parts by weight of an expander that generates a gas upon stimulation. Made of adhesive.

  In still another specific aspect of the expandable adhesive tape according to the present invention, the degree of crosslinking of the expandable adhesive before expansion is 50% or less. In this case, the volume of the expandable adhesive becomes sufficiently large due to expansion. Therefore, the gap between the members can be more reliably sealed.

  In still another specific aspect of the expandable adhesive tape according to the present invention, the expandable adhesive tape includes the expandable layer and does not have an adhesive layer. That is, in the present invention, the expandable adhesive tape itself may exhibit an adhesive force for bonding the members to each other. But the expansible adhesive tape which concerns on this invention may be provided with the adhesive layer laminated | stacked on the at least single side | surface of the said expansion | swelling layer. When the adhesive layer is provided on at least one surface of the expansion layer, it can be joined to the application target member by the adhesive force of the adhesive layer. Accordingly, the degree of freedom in designing the expansion layer can be increased.

  In the case of an expandable adhesive tape provided with the above adhesive layer, the expandable resin composition constituting the expand layer preferably contains a resin and an expander. Since the adhesive layer expresses an adhesive force to the member, the expandable resin composition itself does not need to exhibit an adhesive force to the member. Accordingly, the expandable resin composition can be constituted by appropriately selecting from a wide range of resin materials and expansion agents.

  In still another specific aspect of the expandable adhesive tape according to the present invention, a base material layer laminated on at least one surface of the expandable layer is further provided.

  When the base material layer is provided, the expansibility in the direction perpendicular to the surface normal of the expandable adhesive tape is suppressed, and the expansion direction is concentrated in the surface normal direction. Therefore, it is difficult for the expanded portion of the expandable adhesive tape to protrude from the gap between the members.

  The expandable adhesive and the expandable adhesive tape according to the present invention have a function of filling a gap between members by expanding and bonding the members to each other. Since the volume change is caused by the expansion, it is not necessary to accurately arrange the shapes of the expandable adhesive and the expandable adhesive tape according to the size of the gap between the applied members. In addition, there is no need to position the expandable adhesive and the expandable adhesive tape with high precision when applied between the members. Furthermore, it is not necessary to prepare inflatable adhesives and inflatable adhesive tapes of various shapes and sizes according to the gaps between various members.

  Therefore, by using the expandable adhesive and the expandable adhesive tape of the present invention, it can be easily applied to gaps between various members such as a gap between an image display panel of a portable image device and a protective transparent plate. The gap between the members can be surely sealed only by applying a stimulus and inflating.

FIG. 1 is a cross-sectional view showing an example of use of an expandable adhesive according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an expandable adhesive tape according to an embodiment of the present invention. FIG. 3 is a graph showing the relationship between the light irradiation amount and the tape expandability in the expandable adhesive tape according to one embodiment of the present invention.

  Details of the present invention will be described below.

  The expandable adhesive and the expandable adhesive tape according to the present invention expand by applying a stimulus, fill a gap between members, and bond the members to each other. The expandable adhesive tape of the present invention has an expandable layer that expands when a stimulus is applied. This intumescent layer may be composed of the intumescent adhesive of the present invention, or may be formed from another intumescent resin composition. However, preferably, the expansion layer is made of the expandable adhesive of the present invention. In the following, first, the expandable adhesive of the present invention will be described, and then the details of the expandable adhesive tape of the present invention will be described.

(Expandable adhesive)
The inflatable adhesive according to the present invention expands when a stimulus is applied, thereby filling a gap between the members and bonding the members to each other. As the expansible adhesive, an appropriate adhesive that expands by applying a stimulus and exhibits adhesiveness by applying a stimulus of the same type or different from the stimulus can be used. Preferably, an expandable adhesive that expands by application of a stimulus, has a fixed shape after expansion, and exhibits adhesiveness by applying the same or different stimulus as the above stimulus. In this case, since the shape after expansion is fixed, the gap between the members can be more reliably sealed.

  The expandable adhesive includes an adhesive resin as a component that develops adhesiveness, and an expander. In addition, it is preferable that a curing agent is included in addition to the adhesive resin and the expansion agent in order to fix the shape after expansion.

1) Adhesive resin As said adhesive resin, well-known adhesive constituent resin can be used. Such resins include urethane resins, acrylic resins, silicone resins, phenolic resins, urea resins, epoxy resins, fluorine resins, vinyl resins, butadiene resins, styrene resins, acrylonitrile resins. Resin or the like can be used. These resins may be used alone or in combination of two or more.

  Preferably, an acrylic resin, a silicone resin, a urethane resin, a butadiene resin, or a styrene resin is used as the adhesive resin. These preferable resins are excellent in the elasticity of the cured product. Therefore, the gap between the members can be reliably sealed. Especially, since it is excellent in the adhesiveness with respect to an application member, and it is easy to raise the elasticity of hardened | cured material, acrylic ester resin is used suitably as acrylic resin.

  As (meth) acrylic acid ester resin, (meth) acrylic acid alkyl ester resin obtained by homopolymerizing (meth) acrylic acid alkyl ester monomer, copolymerized with two or more (meth) acrylic acid alkyl ester monomers. (Meth) acrylic acid alkyl ester resin, copolymer of acrylic acid alkyl ester monomer and methacrylic acid alkyl ester monomer, (meth) acrylic acid alkyl ester monomer and other vinyl monomers copolymerizable therewith A copolymer etc. are mentioned. Among them, the adhesive strength can be easily designed by adjusting the composition, and the cured product has excellent elasticity, so that the (meth) acrylic acid alkyl ester monomer and other vinyl monomers copolymerizable therewith A copolymer is preferred. (Meth) acryl shall mean acrylic or methacrylic.

  Although it does not specifically limit as a (meth) acrylic-acid alkylester monomer, What is obtained by esterification reaction of the primary or secondary alkyl alcohol with 1-12 carbon atoms of an alkyl group, and (meth) acrylic acid. Specific examples include ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. In addition, the said (meth) acrylic-acid alkylester monomer may be used independently, or 2 or more types may be used together.

  Another vinyl monomer copolymerizable with the (meth) acrylic acid alkyl ester monomer is added for the purpose of increasing the cohesive strength of the resulting (meth) acrylic ester resin, and i) for example, (meta And those that increase the glass transition temperature (Tg) of the acrylate resin, and ii) those that contribute to the formation of a crosslinked structure between the main chains of the (meth) acrylate resin.

  The vinyl monomer i) that raises the glass transition temperature (Tg) of the (meth) acrylic ester resin is not particularly limited, and examples thereof include carboxy such as (meth) acrylic acid, crotonic acid, maleic acid, and itaconic acid. Group-containing monomers; hydroxyl group-containing monomers such as n-methylolacrylamide; maleic anhydride, vinyl acetate, styrene and the like. As the vinyl monomer, acrylic acid is preferred because it hardly affects the control of the molecular weight of the acrylic ester resin and is excellent in the adhesiveness of the resulting resin.

  If the total content of the vinyl monomer component that raises the glass transition temperature is small, the glass transition temperature of the resulting resin may be too low, and the cohesive strength of the resin may decrease. In some cases, 0.01 to 10% by weight is preferable in the (meth) acrylic ester resin, and 0.05 to 5% by weight is more preferable.

  The vinyl monomer ii) that contributes to the formation of a crosslinked structure between the main chains of the (meth) acrylate resin is not particularly limited, but a hydroxyl group-containing (meth) acrylate ester or a carboxyl group-containing monomer is preferred. .

  By using either one or both of a hydroxyl group-containing acrylic acid ester monomer or a hydroxyl group-containing methacrylate ester monomer and an isocyanate-based crosslinking agent, the gel fraction of the resin can be easily adjusted to a preferred range of 10 to 50% by weight. . Therefore, a resin excellent in expansibility can be obtained.

  Examples of the hydroxyl group-containing acrylate monomer include, for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, and 4-hydroxybutyl acrylate. Or what added caprolactone to acrylic acid-2-hydroxypropyl, etc. are mentioned.

  Examples of hydroxyl group-containing methacrylic acid ester monomers include: 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, and 4-hydroxybutyl methacrylate. Or what added caprolactone to methacrylic acid-2-hydroxypropyl etc. is mentioned.

  The content of the hydroxyl group-containing (meth) acrylic acid ester monomer component is preferably 0.01 to 0.5% by weight and more preferably 0.05 to 0.3% by weight in the acrylic ester resin.

  When there is little content of a hydroxyl-containing (meth) acrylic acid ester monomer component, it will become difficult to raise the gel fraction of resin. Therefore, a large amount of a crosslinking agent may be required to adjust the gel fraction of the resin to an appropriate gel fraction. Moreover, there is a possibility that the crosslinking of the resin proceeds as time passes and the expansibility of the resin becomes unstable.

  If the content of the hydroxyl group-containing (meth) acrylic acid ester monomer component is high, the resin gel fraction tends to increase, and it is necessary to use a small amount of crosslinking agent to adjust the resin gel fraction to an appropriate gel fraction. There may be. Moreover, since the fluctuation | variation of the gel fraction by the variation in the amount of crosslinking agents in resin becomes large, a uniform crosslinked structure may not be obtained.

  By using a carboxyl group-containing monomer and an epoxy-based crosslinking agent or an aziridine-based crosslinking agent, which will be described later, it is easy to adjust the gel fraction of the resin to a preferred range of 10 to 50% by weight, and a resin having excellent expansibility. Obtainable.

  Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid, and itaconic acid.

  The content of the carboxyl group-containing monomer component is preferably from 0.1 to 10% by weight, more preferably from 1 to 5% by weight, in the acrylic ester resin.

  When the content of the carboxyl group-containing monomer component is small, the gel fraction of the resin is difficult to increase, and a large amount of a crosslinking agent may be required to adjust the gel fraction of the resin to an appropriate gel fraction. In addition, the cross-linking of the resin proceeds with time, and the expansibility of the resin may become unstable.

  If the content of the carboxyl group-containing monomer component is high, the gel fraction of the resin tends to increase, and it may be necessary to carry out with a small amount of cross-linking agent to adjust the resin gel fraction to an appropriate gel fraction. . Moreover, since the fluctuation | variation of the gel fraction by the variation in the amount of crosslinking agents in resin becomes large, a uniform crosslinked structure may not be obtained.

  When the weight average molecular weight measured as a polystyrene-equivalent molecular weight by GPC (Gel Permeation Chromatography) method of (meth) acrylic acid ester resin is small, the formed resin layer becomes deformed of the adherend. There is a possibility that peeling from the adherend is likely to occur due to the accompanying peeling stress. On the contrary, if the weight average molecular weight is large, the adhesive strength of the resin is lowered, and further, the formed resin layer may be easily peeled off from the adherend due to the peeling stress caused by the deformation of the adherend. is there. Therefore, the weight average molecular weight is preferably 200,000 to 1,500,000, more preferably 400,000 to 1,000,000.

  The weight average molecular weight of the (meth) acrylic acid ester resin measured as the polystyrene-equivalent molecular weight by the GPC method is a filter obtained by diluting the acrylic acid ester resin with tetrahydrofuran (THF) 50 times. Based on the obtained filtrate, the polystyrene equivalent molecular weight of the acrylic ester resin can be measured by gel permeation chromatography. As said gel permeation chromatograph, what is marketed with the brand name "2690 Separations Model" from Water company etc. can be used, for example.

  In order to obtain a (meth) acrylic ester resin, the presence of a polymerization initiator, together with a (meth) acrylic acid alkyl ester monomer and, if necessary, other vinyl monomers copolymerizable with the (meth) acrylic acid alkyl ester monomer What is necessary is just to carry out a radical reaction under. In addition, as a polymerization method, a conventionally well-known method is used, for example, solution polymerization, emulsion polymerization, suspension polymerization, block polymerization, etc. are mentioned.

  In the (meth) acrylic acid ester resin, it is preferable to add a crosslinking agent to form a crosslinked structure between the main chains of the resin. By appropriately adjusting the type and amount of the crosslinking agent, it becomes easy to adjust the gel fraction of the resin within a desired range.

  It does not specifically limit as a crosslinking agent, For example, an isocyanate type crosslinking agent, an aziridine type crosslinking agent, an epoxy type crosslinking agent, or a metal chelate type crosslinking agent etc. are mentioned.

  When the blending amount of the crosslinking agent is small, the resin may be insufficiently crosslinked, and when it is large, the adhesive strength and tack of the resin may be decreased. Therefore, the blending amount of the crosslinking agent is preferably 0.01 to 10.0 parts by weight and more preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the acrylic ester resin.

  That is, even if the gel fraction of the resin is too high or too low, the resin layer to be formed is easily peeled off from the adherend due to the peeling stress caused by the deformation of the adherend. Moreover, in order to improve expansibility, the gel fraction is preferably 10 to 50% by weight, and more preferably 20 to 40% by weight.

  Here, in the method for measuring the gel fraction of the resin, first, a resin sheet is cut into a flat rectangular shape of 50 mm × 100 mm to prepare a test piece. After this test piece is immersed in ethyl acetate at 23 ° C. for 24 hours, the test piece is taken out from ethyl acetate and dried at 110 ° C. for 1 hour. Next, the weight of the test piece after drying is measured, and the gel fraction is calculated using the following formula.

Gel fraction (% by weight) = 100 × W2 / W1
(W1: Weight of test piece before immersion, W2: Weight of test piece after immersion and drying)

  In the expandable adhesive of the present invention, the adhesive resin preferably exhibits adhesiveness by imparting a stimulus. What is necessary is just to select this irritation | stimulation suitably according to the kind of adhesive resin. Further, the stimulus for developing the adhesive property of the adhesive resin may be the same as or different from the stimulus to be applied in order to develop the swelling action by the swelling agent described later. In addition, as described above, preferably, the expandable adhesive of the present invention expands by application of a stimulus, fixes the shape after expansion by a stimulus of the same or different type as the stimulus, and further exhibits adhesiveness. However, in this case, the stimulus for expressing the swelling action, the stimulus for fixing the shape after the swelling, and the stimulus for developing the adhesiveness may be the same or different. .

  For example, in the case of the (meth) acrylic ester resin, light such as ultraviolet rays can be used as a stimulus for developing adhesiveness. By irradiation with light, the (meth) acrylic acid ester resin can be cross-linked and cured to develop an adhesive force. When the adhesive resin is, for example, an epoxy resin, it is cured by applying heat in addition to light irradiation. As the stimulus, heat may be used, or light such as ultraviolet light (UV) may be used.

2) Swelling agent The expansible adhesive according to the present invention includes a swelling agent that develops a swelling action upon application of a stimulus. As such a swelling agent, a swelling agent that decomposes by giving a stimulus such as heat or light to generate gas is used. An azo compound or an azide compound is preferably used as an expanding agent that decomposes by heat or light to generate a gas.

  Examples of the azo compound include 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylpropyl) -2-methylpropionamide], 2 , 2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylethyl) -2-methylpropionamide], 2,2′-azobis (N-hexyl) -2-methylpropionamide), 2,2′-azobis (N-propyl-2-methylpropionamide), 2,2′-azobis (N-ethyl-2-methylpropionamide), 2,2′-azobis {2-Methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2- ( -Hydroxybutyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis [N- (2-propenyl) -2-methyl Propionamide], 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) Propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrolate, 2,2'-azobis [2- (3,4,5,6) -Tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolyl -2-yl] propane} dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis (2-methylpropionamidyne) hydrochloride, 2, , 2′-azobis (2-aminopropane) dihydrochloride, 2,2′-azobis [N- (2-carboxyacyl) -2-methyl-propionamidine], 2,2′-azobis {2- [ N- (2-carboxyethyl) amidyne] propane}, 2,2′-azobis (2-methylpropionamidoxime), dimethyl 2,2′-azobis (2-methylpropionate), dimethyl 2,2′- Azobisisobutyrate, 4,4′-azobis (4-cyancarbonic acid), 4,4′-azobis (4-cyanopentanoic acid) Sid), 2,2'-azobis (2,4,4-trimethylpentane) and the like.

  Among them, 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylpropyl) -2-methylpropionamide], 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylethyl) -2-methylpropionamide], 2,2′-azobis (N-hexyl-2-methylpropion) Amido), 2,2′-azobis (N-propyl-2-methylpropionamide), 2,2′-azobis (N-ethyl-2-methylpropionamide) and the like are preferred.

  Since the azoamide compound has a high thermal decomposition temperature, it can be subjected to a high-temperature treatment such as adhesive coating and drying. Moreover, it is excellent also in the solubility to the polymer which has adhesiveness, such as acrylic ester resin.

  Examples of the azide compound include 3-azidomethyl-3-methyloxetane, terephthalazide, p-tert-butylbenzazide, and glycidyl azide polymer obtained by ring-opening polymerization of 3-azidomethyl-3-methyloxetane. And a polymer having an azide group. These azide compounds are decomposed by stimulation with light, heat, etc., and generate nitrogen gas.

3) Preferred Form As described above, the expandable adhesive according to the present invention expands by applying a stimulus, and cures by applying the same or different kind of stimulus as the stimulus, and exhibits adhesiveness. In this case, it is desirable that the stimulus for decomposing the expansion agent and expanding the expandable adhesive and the stimulus for curing the adhesive resin and exhibiting adhesiveness are the same type. Thereby, the equipment for applying the stimulus can be omitted, and the process can be simplified. Further, as described above, preferably, an expandable adhesive that expands by applying a stimulus, fixes a shape after expansion, and develops adhesiveness is desirable. In this case, the stimulus for expressing the expansion action, the stimulus for fixing the shape after the expansion, and the stimulus for expressing the adhesiveness may all be different. However, it is desirable that at least two of the first to third stimuli are of the same type, and more preferably, all of the first to third stimuli are of the same type. In that case, the equipment for applying the stimulus can be simplified, and the process can be simplified.

  Hereinafter, a preferred embodiment of the present invention in which the expandable adhesive expands by applying a stimulus, fixes the shape after expansion by applying the same type of stimulus, and develops adhesiveness will be described. In this preferred form, the expansion agent is decomposed by light irradiation, and the expandable adhesive expands. On the other hand, the adhesive component is also cured, and the expanded shape is fixed to develop adhesiveness.

  In this case, the adhesive resin used for the expandable adhesive that cures by irradiation with light and fixes the shape after expansion and develops adhesiveness is fixed to express the adhesiveness after expansion. In order to achieve this, it is desirable to include the ion-reactive group-containing (meth) acrylic ester resin and a curing agent composed of an ion polymerization catalyst described later. Examples thereof include ion-reactive group-containing (meth) acrylic acid ester-based resins obtained by polymerizing a monomer composition containing a monomer having an ion-reactive group. In this case, what is necessary is just to copolymerize the monomer which has an ion reactive group as 1 type of the monomer used for obtaining the (meth) acrylic acid ester-type resin mentioned above.

  Or you may mix | blend the below-mentioned ion reactive group containing compound and an ion polymerization catalyst with the adhesive resin mentioned above which does not have an ion reactive group as another method.

  When the ion-reactive group-containing monomer is copolymerized with the (meth) acrylic acid ester-based resin, the ion-reactive group-containing (meth) acrylic monomer is preferably used as the ion-reactive group-containing monomer. .

  In this case, it is desirable to decompose the swelling agent at a wavelength different from the wavelength at which the ion polymerization catalyst is activated by light irradiation. For example, when the ion polymerization catalyst is activated by light having a wavelength shorter than 400 nm, a compound that is sensitive to light having a wavelength longer than 400 nm, such as near-ultraviolet light, is used as the photoexpansion agent. However, even if the decomposition wavelength of the photoexpansion agent and the excitation wavelength of the ionic polymerization catalyst overlap, there is a difference in the reaction rate between the decomposition reaction and the ionic polymerization reaction, so that both expandability, post-curing property and adhesiveness are compatible. be able to.

  Here, a (meth) acrylic monomer containing an ion-reactive group undergoes ion polymerization by ions such as cations generated when the ion polymerization catalyst is activated when irradiated with light and / or heated. It is a (meth) acrylic monomer having a group. That is, since it has ion polymerizability, it hardens | cures and the adhesive agent hardened | cured material expanded is fixed.

  In addition, the (meth) acrylic-type monomer containing an ion reactive group has a (meth) acryl group. Accordingly, the (meth) acrylic monomer containing an ion reactive group can be obtained by a conventional polymerization method such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, and the like. It can be copolymerized with monomers or other vinyl monomers copolymerizable therewith.

  As the ion reactive group in the (meth) acrylic monomer having an ion reactive group that is cured when irradiated with light and / or heated, an anionic functional group and a cationic functional group exist.

  Examples of the cation reactive group include an epoxy group, an oxetanyl group, a vinyloxy group, a styryl group, and an alkoxysilyl group.

  Examples of the anionic functional group include an epoxy group, an alkoxysilyl group, and a (meth) acryloyl group.

  As the ion reactive group, an epoxy group, an oxetanyl group, a vinyloxy group, a styryl group, an alkoxysilyl group and the like are preferable because of high reactivity.

  The (meth) acrylic monomer having an ion reactive group is not particularly limited as long as it is an acrylic monomer having an ion reactive group. For example, as a (meth) acrylate having an epoxy group, glycidyl (meth) acrylate, CYCLOMER M-100 (manufactured by Daicel Chemical Industries) can be mentioned.

  In the method of blending the ion-reactive group-containing compound with the (meth) acrylic ester resin, a compound containing a bifunctional ion-reactive group is preferably used.

  Here, as a compound having a bifunctional ion-reactive group, there is a compound that is cured by light irradiation and / or heating.

  Examples of such a compound having a bifunctional ion-reactive group include compounds having two or more ion-reactive functional groups such as an epoxy group, an oxetanyl group, a vinyloxy group, a styryl group, and an alkoxysilyl group in one molecule. be able to. More specifically, examples include various epoxy compounds that are cured by light irradiation and / or heating. Examples of such epoxy compounds include bisphenol A type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, epoxidized soybean oil, and epoxidized SBS. Can be mentioned.

  The compounding amount of the compound having an ion reactive group is preferably 1 to 30 parts by weight and more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the acrylic ester resin.

  When there are too few compounding quantities of the compound which has the said ion reactive group, the cure degree of an expandable adhesive agent will become difficult to raise, and fixation of the shape of an expansion layer may become difficult.

  When there are too many compounding quantities of the compound which has the said ion reactive group, the hardening degree of an expandable adhesive agent may become high too much. Therefore, the expansion layer becomes too hard, and there is a possibility that the impact absorbability is lowered.

  Next, the curing agent will be described.

4) Curing Agent In the expandable adhesive according to the present invention, it is preferable to contain a curing agent in addition to the adhesive resin and the swelling agent. Similarly, in the expandable adhesive tape according to the present invention, it is desirable that the expansion layer contains a curing agent.

  By containing the curing agent, the shape retention after curing of the adhesive resin can be enhanced, and the shapes of the expandable adhesive and the expanded layer after expansion can be more reliably fixed. As such a curing agent, an ion polymerization catalyst is preferably used.

  Here, the ion polymerization catalyst is activated by light irradiation or heating to generate ions, and contains an ion reactive group derived from a (meth) acrylic monomer containing an ion reactive group or the above ion reactive group It is a compound that ionically polymerizes or crosslinks an ion reactive group of a compound and cures the compound.

  When utilizing light irradiation, the ion polymerization catalyst is a photoion polymerization catalyst. Examples of the photoion polymerization catalyst include compounds that generate cations upon irradiation with light, such as photosensitive onium salts and ferrocene compounds. Various photocationic polymerization initiators can be used as the cation-generating compound. Examples of the photocationic polymerization initiator include photosensitive onium salts such as aromatic diazonium salts, aromatic halonium salts, aromatic sulfonium salts, metallocene salts such as iron-allene complexes, titanocene complexes, and arylsilanol-aluminum complexes, or pyridinium. There is salt.

  Aromatic iodonium salts and aromatic sulfonium salts do not generate cations in light other than the ultraviolet region, but are known sensitizers such as aromatic amines and polycyclic aromatic hydrocarbons, and have an excitation absorption band in the visible light region. In combination with a sensitizer having a cation, a cation can be generated even in light in the visible region. Further, when a metallocene salt is used, an oxalate ester of tertiary alcohol may be used as a reaction accelerator.

  More specifically, as the photosensitive onium salt, SbF6-, PF6-, BF4-, and B (PhF5) 4- such as triarylsulfonium salt, diarylsulfonium salt, and diaryliodonium salt are used as counter anions. Can be mentioned. Examples of the iron-allene complex include an Fe-ferrocene complex.

  Commercially available photocationic polymerization initiators are broadly classified into ionic photoacid generation types and nonionic photoacid generation types. Examples of ionic photoacid generation type photocationic polymerization initiators include the trade name “ Adekaoptomer SP150 ”,“ Adekaoptomer SP170 ”(manufactured by Asahi Denka Kogyo Co., Ltd.), trade name“ UVE-1014 ”(manufactured by General Electronics Co., Ltd.), trade name“ CD-1012 ”(manufactured by Sartomer), etc. Can be mentioned.

  Examples of the nonionic photoacid generation type photocationic polymerization initiator include nitrobenzyl ester, sulfonic acid derivative, phosphoric ester, phenol sulfonic acid ester, diazonaphthoquinone, N-hydroxyimidosulfonate, and the like.

  As for the said photoion polymerization catalyst, only 1 type may be used independently and 2 or more types may be used.

  The blending ratio of the photoion polymerization catalyst is 0.1 to 100 parts by weight of a compound having at least two (meth) acrylic monomers or ion-reactive functional groups containing an ion-reactive group in one molecule. The range is preferably 50 parts by weight, more preferably 1 to 10 parts by weight. If it is less than 0.1 part by weight, there is a possibility that the progress of ionic polymerization is slow or the hardness is finally insufficient even when irradiated with light. If it exceeds 50 parts by weight, the physical properties of the resulting cured adhesive may be reduced.

  In addition, when using a photoionic polymerization catalyst as said ion polymerization catalyst, you may use a thermosetting agent together. In that case, the expandable adhesive can be finally cured by applying both light and heat.

  The ion polymerization catalyst may be a thermosetting agent activated by heat. In this case, the expandable adhesive can be cured by heating.

  Examples of such a thermosetting agent include a curing agent having an appropriate amine and / or thiol group. Hydrazide compounds such as 1,3-bis [hydrazinocarbonoethyl-5-isopropylhydantoin], dicyandiamide, guanidine derivatives, 1-cyanoethyl-2-phenylimidazole, N- [2- (2-methyl-1-imidazolyl) Ethyl] urea, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, N, N′-bis (2-methyl-1-imidazolylethyl) urea, N , N ′-(2-methyl-1-imidazolylethyl) -adipamide, 2-phenyl-4-methyl-5-hydroxymethylimidazole, imidazole derivatives such as 2-phenyl-4,5-dihydroxymethylimidazole, modified aliphatic Polyamine, tetrahydrophthalic anhydride, ethylene glycol bis (anhydrotrimellite Vii) acid anhydrides, such as, addition products such as the various amines and epoxy resins.

  About the compounding ratio of the said thermosetting agent, it is 1-100 weight part with respect to 100 weight part of compounds which have two or more (meth) acrylic-type monomers or ion-reactive functional groups containing an ion reactive group in 1 molecule. It is preferable to set it as the range of this, More preferably, it is the range of 5-50 weight part. If it is less than 1 part by weight, the progress of ionic polymerization may be slow or the hardness may be insufficient even when irradiated with light. If it exceeds 100 parts by weight, the properties of the resulting expandable adhesive may be reduced.

5) Physical property of hardened | cured material When using the expansible adhesive agent of this invention, an expansible adhesive agent is filled between the to-be-adhered member surface and to-be-adhered members in the step where a crosslinking degree is low. Thereafter, the expandable adhesive is expanded by applying a stimulus such as light or heat, and preferably, by applying the same or different type of stimulus, it is cured to develop an adhesive force. More preferably, by applying the same or different kinds of stimuli, the shape of the expanded adhesive cured product is fixed, and an adhesive force is developed. Further, by setting the tan δ after expansion and curing of the expandable adhesive to an appropriate value, the expandable adhesive layer can have a shock absorbing performance function. When the tan δ of the cured product of the expandable adhesive is 0.5 or more at 25 ° C., preferable shock absorbing performance is obtained. When tan δ at 25 ° C. is less than 0.5, the viscosity term of the resin becomes small and the resin is hard to deform. In that case, when external force is applied, the resin is not easily deformed, and an appropriate shock absorbing performance may not be obtained.

  Here, tan δ refers to the ratio of loss elastic modulus / storage elastic modulus, and can be measured with a viscoelastic spectrometer.

  tan δ can be set to 0.5 or more by adjusting, for example, the type of adhesive resin of the expandable adhesive, the resin composition, the molecular weight, and / or the degree of crosslinking.

  Moreover, you may add additives, such as a plasticizer, an emulsifier, a softener, a filler, a pigment, and dye, to the said expandable adhesive agent by this invention as needed.

(Expandable adhesive tape)
Details of the expandable adhesive tape will be described.

  The expandable adhesive tape according to the present invention has an expandable layer made of an expandable resin composition that expands by applying a stimulus and fills a gap between the members, and bonds the member and the member. Preferably, it has an expansion layer made of an expandable resin composition that expands by applying a stimulus, fixes the shape after expansion by stimuli of the same type or different from the stimulus, and fills the gaps between the members. Here, as the expansive resin composition constituting the expansive layer, the expansive adhesive of the present invention described above can be suitably used. However, the intumescent layer is not limited to the inflatable adhesive of the present invention.

  That is, an expandable resin composition other than the expandable adhesive of the present invention may be used. Examples of the expandable resin composition other than the expandable adhesive of the present invention include a composition containing a resin and an expander that generates a gas upon application of a stimulus. Preferably, the expandable resin composition further includes a curing agent that fixes the shape after expansion by the same or different stimulus as the stimulus. As such a curing agent, the various ion polymerization catalysts described above can be suitably used.

  Moreover, as resin used for expandable resin compositions other than the said expandable adhesive agent, appropriate resin which can hold | maintain the form of an expandable tape can be used. Examples of such resins include the urethane resins, acrylic resins, silicone resins, phenol resins, urea resins, epoxy resins, fluorine resins, vinyl resins, butadiene resins, styrene resins, and acrylonitrile. Various resins such as olefin resin can be used without being limited to the resin.

  Moreover, you may use the resin component formed by blending multiple types of resin.

  As the expansion agent that generates gas by applying the stimulus, the expansion agents exemplified in the description of the expandable adhesive described above can be similarly used.

  In the expandable adhesive tape according to the present invention, an adhesive layer may be further laminated on at least one surface of the expandable layer. Examples of such an adhesive layer include a synthetic rubber adhesive, a natural rubber adhesive, and an acrylic adhesive.

  When the said adhesive layer is provided in the at least single side | surface of the expansion layer, the function to adhere | attach a member and a member by an adhesive layer is acquired. Therefore, the intumescent layer can be configured with emphasis on the inflatable function, preferably the inflatable function and the shape fixing function after expansion. Therefore, the expansion layer can be configured optimally for the expansion layer from various materials.

  The adhesive strength of the expandable adhesive tape according to the present invention is preferably in the range of 2 to 20 N / 25 mm. When the adhesive strength is in a preferable range, the members can be more reliably bonded to each other, and the gap between the members can be reliably sealed. Moreover, in the expandable adhesive tape which concerns on this invention, when an expansion layer consists of expandable adhesives, the expansion agent which generate | occur | produces gas by irritation | stimulation with respect to 100 weight part of adhesive resin contains 5-50 weight part The composition is preferred for the reasons described above. In this case, the degree of crosslinking of the expandable adhesive before expansion is preferably 50% or less. When the degree of crosslinking, that is, the gel fraction described above is 50% or less, expansion due to decomposition of the expansion agent proceeds without difficulty. Accordingly, the expandability can be further enhanced.

  In the expandable adhesive tape according to the present invention, a base material layer may be laminated on at least one surface of the expandable layer. As the material constituting the base material layer, resin materials excellent in various formations such as polyolefin and polyester can be used. Since the shape retention before use is improved when the base material layer is provided, handling can be facilitated. The base material layer is preferably removed when applied to the gap between the members. However, depending on the application, when the gap between the members is filled, the member layer may be applied to the gap while being laminated on the expansion layer.

(Adhesion method)
Next, a method for bonding members using the expandable adhesive or the expandable adhesive tape according to the present invention will be described.

  First, an expandable adhesive is applied to one side or both sides of a member to be bonded. In the case of an expandable adhesive tape, the expandable adhesive tape is affixed to one or both sides of the member to be bonded.

  Next, a stimulus is applied to the expandable adhesive or the expandable adhesive tape, and the expandable adhesive is bonded. Preferably, the shape after expansion is fixed and adhered by applying stimulus.

  Examples of the stimulus include light such as UV or heat as described above. The application of the stimulus can be performed by irradiating and / or heating UV to the gap between the adherend members, which is heated together with the adherend member. When the member to be bonded transmits UV, UV may be irradiated through the member to be bonded.

  Next, a method for using the expandable adhesive and the expandable adhesive tape according to one embodiment of the present invention will be specifically described with reference to the drawings.

  FIGS. 1A and 1B are sectional views for explaining an example used for fixing a display panel to a case of a mobile phone. A display panel 2 is disposed in the case 1 of the mobile phone. In this state, a gap A exists between the outer surface 2 a of the display panel 2 and the inner wall 1 a of the case 1. In this gap A, the expandable adhesive tape 3 as one embodiment of the present invention thinner than the thickness of the gap A is disposed. Since the thickness of the expandable adhesive tape 3 is smaller than the thickness of the gap, that is, the distance between the outer surface 2a of the display panel 2 and the inner wall 1a of the case 1, the expandable adhesive tape 3 is easily disposed in the gap A. can do. Therefore, when applying the expandable adhesive tape 3, highly accurate positioning is not required.

  Next, a stimulus such as light or heat is applied to the expandable adhesive tape 3, and as a result, the expandable adhesive tape 3 expands. Accordingly, as shown in FIG. 1B, the expanded adhesive tape 3 </ b> A after expansion fills the gap A and further bonds the outer surface 2 a of the display panel 2 and the inner wall 1 a of the case 1. Therefore, the space between the outer surface 2a of the display panel 2 and the inner wall 1a of the case 1 can be reliably sealed.

  The expandable adhesive tape and expandable adhesive have bubbles inside after expansion. Therefore, it is excellent in elasticity, and the display panel 2 can be reliably protected from an external impact.

  In this case, preferably, when the expandable adhesive tape 3A after expansion has elasticity, the display panel 2 can be more reliably protected against impacts and the like. Therefore, it is preferable that the expansion layer has elasticity after expansion. Therefore, when the expansion layer is composed of the expandable adhesive of the present invention, the above-described (meth) acrylic ester resin is preferably used as an adhesive component having excellent elasticity of the cured product. Moreover, you may use the other adhesive component excellent in elasticity for hardened | cured materials, such as a silicone type resin.

  1A and 1B, the expandable adhesive tape 3 has been described. However, instead of the expandable adhesive tape 3, an expandable adhesive may be used. In that case, when the expandable adhesive does not have shape retention, a method of applying the expandable adhesive to the outer surface 2 a of the display panel 2, and applying the expandable adhesive to the inner wall 1 a of the case 1. A method, or a method of applying an expandable adhesive to both of them can be used.

  FIG. 2 is a cross-sectional view showing the structure of an expandable adhesive tape as another embodiment of the present invention. The expandable adhesive tape 11 of this embodiment has an expandable layer 12. Adhesive layers 13 and 14 are laminated on both surfaces of the expansion layer 12. That is, it is a laminate having a three-layer structure including the pressure-sensitive adhesive layer 13 -the expansion layer 12 -the pressure-sensitive adhesive layer 14. Thus, the expandable adhesive tape of the present invention may have a structure in which the pressure-sensitive adhesive layer is laminated on both surfaces of the expanded layer. In this case, the pressure-sensitive adhesive layers 13 and 14 on both sides can exhibit an adhesive force to the applied member. In addition, release films 15 and 16 are laminated on the outside of the pressure-sensitive adhesive layers 13 and 14. The release films 15 and 16 can be composed of an appropriate synthetic resin film such as a polyethylene terephthalate film. The release films 15 and 16 are removed prior to use.

  Next, the present invention will be clarified by giving specific examples and comparative examples.

Example 1
As described below, an expandable adhesive tape having a three-layer structure of pressure-sensitive adhesive layer-expanded layer-pressure-sensitive adhesive layer was prepared and evaluated.

  As a material for forming the expansion layer, an acrylic polymer (copolymerization ratio: 96.7 parts by weight of 2-ethylhexyl acrylate / 3 parts by weight of acrylic acid / 0.3 parts by weight of 2-hydroxyethyl acrylate, weight average) 100 parts by weight of molecular weight: 600,000), 20 parts by weight of 2,2′-azobis (N-butyl-2-methylpropionamide) as an expanding agent, and an isocyanate-based crosslinking agent (Coronate L45, Nippon Polyurethane as a crosslinking agent) An acrylic polymer solution prepared by mixing and dissolving 2 parts by weight of 280 parts by weight of ethyl acetate was prepared.

  The acrylic polymer solution was applied onto a release-treated polyethylene terephthalate (PET) film (thickness 50 μm) and dried at 110 ° C. for 5 minutes to form an expanded layer having a thickness after drying of 50 μm.

  In order to form an adhesive layer, an acrylic polymer (copolymerization ratio: 51.9 parts by weight of butyl acrylate / 30 parts by weight of 2-ethylhexyl acrylate / 15 parts by weight of ethyl acrylate / 3 parts by weight of acrylic acid / acrylic acid) 0.1 parts by weight of 2-hydroxyethyl, 100 parts by weight of average weight molecular weight: 800,000) and polymerized rosin ester resin as a tackifier (hydroxyl value: 46, softening point: 152 ° C., manufactured by Arakawa Chemical Co., Ltd.) 15 weights Parts, hydrogenated rosin ester resin (hydroxyl value: 40, softening point: 125 ° C., manufactured by Arakawa Chemical Co., Ltd.), terpene phenol resin (softening point: 150 ° C., 10 parts by weight manufactured by Yasuhara Chemical Co., Ltd.) An acrylic polymer obtained by mixing and dissolving 1 part by weight of an isocyanate-based crosslinking agent (Coronate L45, manufactured by Nippon Polyurethane) in 315 parts by weight of ethyl acetate. The acrylic polymer solution for forming the pressure-sensitive adhesive layer was applied on a polyethylene terephthalate (PET) film (thickness 50 μm) subjected to a release treatment, dried at 110 ° C. for 5 minutes, and the thickness after drying. Formed a 30 μm pressure-sensitive adhesive layer.

  After laminating the pressure-sensitive adhesive layer on the expanded layer formed as described above, and then peeling off the PET film laminated on the back surface of the expanded layer, the pressure-sensitive adhesive layer is further formed on the exposed surface of the expanded layer. Were laminated. In this way, an expandable adhesive tape having a three-layer structure of pressure-sensitive adhesive layer-expanded layer-pressure-sensitive adhesive layer was produced.

For this expandable adhesive tape, an ultra-high pressure mercury lamp was used, the illuminance was 100 mW / cm ² , the irradiation time was changed, and the irradiation light intensity was changed to 900, 3000, or 6000 mJ / cm ^2. Irradiated. The thickness of the expandable adhesive tape when each light amount was irradiated was determined. The results are shown in FIG.

  As is clear from FIG. 3, it can be seen that the tape thickness increases and the expansibility is excellent as the amount of light increases.

  Moreover, about the said expandable adhesive tape, 1) Adhesive strength evaluation, 2) Measurement of a gel fraction, 3) Tan δ of an expansion layer in 25 degreeC, 4) Impact absorption evaluation, and 5) Sealing evaluation in the following ways. went.

1) Adhesive strength evaluation The adhesive strength evaluation is the opposite of the expandable adhesive tape SUS plate on the SUS plate as the adherend after curing the expandable adhesive tape obtained as described above at 40 ° C for 1 day. Bonding was performed by reciprocating a 2 kg rubber roller on the side surface. After bonding, the 180 ° peel force after 20 minutes at 23 ° C. was measured under a peeling rate of 300 mm / min. This 180 ° peel force was defined as adhesive strength.

2) Measurement of gel fraction The gel fraction is obtained by curing the expanded layer obtained as described above at 40 ° C. for 1 day, and then cutting it into a flat rectangular shape of 50 mm × 100 mm to prepare a test piece. After this test piece is immersed in ethyl acetate at 23 ° C. for 24 hours, the test piece is taken out from ethyl acetate and dried at 110 ° C. for 1 hour. Next, the weight of the test piece after drying is measured, and the gel fraction is calculated using the following formula.

Gel fraction (% by weight) = 100 × W2 / W1
(W1: Weight of test piece before immersion, W2: Weight of test piece after immersion and drying)

3) Measurement of tan δ at 25 ° C. of expanded layer After curing the expanded layer obtained as described above at 40 ° C. for 1 day, a viscoelastic spectrometer (product number DVA-200, manufactured by IT Measurement Control Co., Ltd.) was used. The temperature dispersion was measured at a frequency of 10 Hz, and Tan δ at 25 ° C. was measured.

4) Impact absorption evaluation The shock absorption evaluation was performed by measuring the impact force using a pendulum type tester. As the pendulum type tester, an impactor made of a steel ball having a diameter of 19 mm and a weight of 0.27 N and a support rod having a length of 350 mm was used. The expandable adhesive tape obtained as described above was cured at 40 ° C. for 1 day, cut into a shape of 20 mm × 20 mm, and bonded to an aluminum plate. The impact force when the steel ball collides with the bonded expandable adhesive tape was detected with a force sensor, and measured with Multi-Purpose FTT Analyzer (manufactured by Ono Sokki Co., Ltd.).

5) Sealability evaluation Sealability evaluation was performed by attaching one of the expandable adhesive tapes obtained as described above to a gap of 200 μm between a pair of members made of SUS plates, and using an ultrahigh pressure mercury lamp (illuminance of 100 mW / cm ^2).
) Was irradiated with an irradiation light amount of 5000 mJ / cm ² ultraviolet rays. One hour after irradiation, the sealing condition of the gap between the pair of members was visually observed.

(Example 2)
An acrylic polymer solution for forming an intumescent layer was prepared by adding an acrylic polymer (copolymerization ratio: 2-ethylhexyl acrylate 86.7 parts by weight / glycidyl methacrylate 10 parts by weight as a monomer having an ion reactive group / acrylic acid 3 parts by weight). / 100 parts by weight of 2-hydroxyethyl acrylate, 0.3 parts by weight, weight average molecular weight: 600,000) and 20 parts by weight of 2,2′-azobis (N-butyl-2-methylpropionamide) as a swelling agent 2 parts by weight of a cationic photopolymerization initiator (made by ADEKA, product number Adekaoptomer SP-170) as an ion polymerization catalyst and 2 parts by weight of an isocyanate-based crosslinking agent (Coronate L45, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent In the same manner as in Example 1, except that it was changed to one obtained by mixing and dissolving in 280 parts by weight of ethyl acetate. A tonic adhesive tape was prepared.

(Example 3)
In the expansion layer forming acrylic polymer solution, the expansion was performed in the same manner as in Example 2 except that the amount of the isocyanate crosslinking agent (Coronate L45, manufactured by Nippon Polyurethane Co., Ltd.) as the crosslinking agent was changed to 1 part by weight. Adhesive tape was prepared.

Example 4
An acrylic polymer solution for forming an intumescent layer was prepared by adding an acrylic polymer (copolymerization ratio: 2-ethylhexyl acrylate 56.7 parts by weight / butyl acrylate 30 parts by weight / glycosyl methacrylate methacrylate as a monomer having an ion reactive group) Parts / part 3 parts by weight acrylic acid / 0.3 parts by weight 2-hydroxyethyl acrylate, 100 parts by weight average molecular weight: 600,000) and 2,2′-azobis (N-butyl-2-methyl) as a swelling agent 20 parts by weight of propionamide), 2 parts by weight of a photocationic polymerization initiator (product of ADEKA, product number Adekaoptomer SP-170) as an ion polymerization catalyst, and an isocyanate-based crosslinking agent (Coronate L45, Nippon Polyurethane as a crosslinking agent) Except that 2 parts by weight) were changed to those obtained by mixing and dissolving 280 parts by weight of ethyl acetate. In the same manner as in Example 1, an expandable adhesive tape was produced.

(Comparative Example 1)
The same procedure as in Example 1 was conducted except that 20 parts by weight of 2,2′-azobis (N-butyl-2-methylpropionamide) as an expanding agent was not blended in the acrylic polymer solution for forming the expanding layer. An expandable adhesive tape was produced.

(Example 5)
An expandable adhesive tape having a single-layer structure having only an expandable layer made of an expandable adhesive and having no pressure-sensitive adhesive layer or adhesive layer was produced. Acrylic polymer solution for forming an intumescent layer was prepared by adding acrylic polymer (copolymerization ratio; butyl acrylate 66.9 parts by weight / methyl methacrylate 30 parts by weight, acrylic acid 3 parts by weight, 2-hydroxyethyl acrylate 0.3 weight Part, weight average molecular weight: 600,000) 100 parts by weight and 2,2′-azobis (N-butyl-2-methylpropionamide) 20 parts by weight as a swelling agent, a compound having a bifunctional ion-reactive group 10 parts by weight of a bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., product number jER828, epoxy equivalent 186) and 1 part by weight of an isocyanate-based crosslinking agent (Coronate L45, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent Prepared by mixing and dissolving in 3000 parts by weight.

  The acrylic polymer solution is applied onto a polyethylene terephthalate (PET) film (thickness 50 μm) subjected to a release treatment, and dried at 110 ° C. for 5 minutes to form an expanded layer having a thickness of 50 μm after drying. An expandable adhesive tape having a single-layer structure supported on the substrate was obtained.

(Comparative Example 2)
Except that 20 parts by weight of 2,2′-azobis (N-butyl-2-methylpropionamide) as a swelling agent was not blended in the acrylic polymer solution for forming the swelling layer, the same as in Example 5. An expandable adhesive tape was produced.

(Evaluation results)
The expandable adhesive tapes of Examples 2 to 4 and Comparative Example 1 were evaluated in the same manner as in Example 1.

  In addition, for the expandable adhesive tapes of Example 5 and Comparative Example 2, as in Example 1, the measurement of gel fraction, the measurement of ten δ at 25 ° C. of the expanded layer, the impact absorption evaluation and the sealing performance evaluation were performed. went. However, the adhesive evaluation was performed as follows in Example 5 and Comparative Example 2.

  Adhesive evaluation of Example 5 and Comparative Example 2: A pair of SUS plates were prepared as adherends. An expandable layer of an expandable adhesive tape cured for one day at 40 ° C. was bonded onto one SUS plate, and after the PET film was peeled off, the other SUS plate was laminated on the expandable layer. Next, on the upper surface of the upper SUS plate, a 2 kg rubber roller was reciprocated once, and a pair of SUS plates were bonded together with an expansion layer made of the expandable adhesive resin. Next, after 20 minutes at 23 ° C., the shear peeling force of the SUS plate was measured under the condition of a peeling speed of 300 mm / min. Adhesiveness was evaluated based on this shear peeling force.

  The evaluation results of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1 below.

DESCRIPTION OF SYMBOLS 1 ... Case 1a ... Inner wall 2 ... Display panel 2a ... Outer surface 3 ... Expandable adhesive tape 3A ... Expandable adhesive tape 11 ... Expandable adhesive tape 12 ... Expandable layer 13,14 ... Adhesive layer 15,16 ... Release film

Claims (14)

  An expandable adhesive that expands by applying a stimulus to fill a gap between the members and bonds the members to each other.   The expandable adhesive according to claim 1, wherein the expanded shape is fixed and the member is bonded to the member. Expandable adhesive according to claim 1 or 2 adhesion strength in the range of 200~600N / 4cm ^2.   The inflatable adhesive according to any one of claims 1 to 3, comprising 100 parts by weight of an adhesive resin and 5 to 50 parts by weight of an inflating agent that generates gas upon stimulation.   The expandable adhesive according to any one of claims 1 to 4, wherein the degree of crosslinking before expansion is 50% or less.   The expandable adhesive according to any one of claims 1 to 5, wherein tan δ at 25 ° C after expansion and curing is 0.5 or more and 1.0 or less.   An inflatable adhesive tape having an intumescent layer made of an intumescent resin composition that fills a gap between members by expansion by applying a stimulus, and adheres the member to the member.   The expandable adhesive tape according to claim 7, wherein the expansion layer fixes the shape after expansion and bonds the member to the member.   The expandable adhesive tape according to claim 7 or 8, wherein the adhesive strength is 2 to 20 N / 25 mm.   10. The expandable adhesive composition according to claim 7, wherein the expandable resin composition comprises an expandable adhesive containing 100 parts by weight of an adhesive resin and 5 to 50 parts by weight of an expander that generates gas upon stimulation. The expandable adhesive tape as described.   The expandable adhesive tape according to claim 10, wherein the expandable adhesive has a degree of crosslinking before expansion of 50% or less.   The expandable adhesive tape according to any one of claims 7 to 11, comprising the expandable layer and having no adhesive layer.   The expandable adhesive tape according to any one of claims 7 to 9, further comprising an adhesive layer laminated on at least one surface of the expandable layer.   The expandable adhesive tape according to any one of claims 7 to 13, further comprising a base material layer laminated on at least one surface of the expandable layer.

Images