Adhesive sheet, laminate using the adhesive sheet, and method for producing the same

Abstract

To provide an adhesive sheet which can be joined without restrictions of light permeability and heat resistance of an adherend, and has high following adhesion to an adherend surface and high cooling / heating cycle resistance characteristics, and a laminate using the adhesive sheet and a method for manufacturing the same.SOLUTION: There are provided an adhesive sheet that has an adhesive layer which contains a photosetting resin (A) having a polymerizable functional group other than a polymerizable unsaturated double bond, a thermoplastic resin (B) having a polymerizable functional group other than the polymerizable unsaturated double bond, and a photopolymerization initiator (C), in which a content of the thermoplastic resin (B) in the adhesive layer is within a predetermined range; and a laminate using the adhesive sheet and a method for manufacturing the same.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive sheet that can be suitably used for bonding two members.

Background Art

[0002] Display devices such as televisions, smartphones, personal assistant devices (PADs), tablet computers, and car navigation systems usually have a configuration in which members such as display panels, wiring boards, lighting devices, and other electronic components are combined.

[0003] For example, many of the members constituting the display device have steps on the surface because various components are arranged on one component. Therefore, in the manufacture of a display device, when joining a member having such steps on the surface to another member, for example, a method of applying an adhesive is used. Specifically, an adhesive is applied to the adherend surface having steps to fill the surface steps, and then the applied adhesive is squeegeed to remove thickness unevenness to smooth the surface to which the adhesive is applied, and then another member is bonded (see, for example, Patent Document 1). However, in this method, it is necessary to manage the application amount of the adhesive, and since it takes time for the cleaning process after application, a joining method alternative to the adhesive is required from the viewpoint of work efficiency improvement.

[0004] On the other hand, as a joining method alternative to the adhesive, there is a method of using an adhesive sheet in which the adhesive is formed into a sheet. According to this method, for example, by bonding a first member to one side of the adhesive sheet and a second member to the other side, the interval between the first member and the plurality of second members is uniquely determined by the thickness of the adhesive sheet, so that the thickness adjustment becomes easy, and also, adjustment of the application amount and cleaning are not required, and the joining operation can be simplified (see Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, when joining members using a photocurable adhesive sheet, it is necessary to prepare a laminate by bringing the members into contact with the adhesive sheet in advance before irradiating light, and irradiate the laminate with light through the members to advance the curing reaction of the adhesive layer in the adhesive sheet. However, in order to irradiate the adhesive sheet with sufficient light to cause a curing reaction, light transmissivity of the members is required. For example, when using members with low light transmissivity or members that do not transmit light, joining by the above-described method is difficult. Similarly, when joining members using a thermosetting adhesive sheet, it is necessary to heat and pressurize at a high temperature in order to sufficiently advance the curing reaction, but this method cannot be applied to joining members with low heat resistance, and heating and pressurization can cause thermal degradation, damage, and functional deterioration of the members and parts.

[0007] In addition, in order to firmly join the members, follow-up adhesion of the adhesive sheet to the adherend surface of the members is required. However, in photocurable and thermosetting adhesive sheets, curing rapidly progresses immediately after light irradiation or heating, so flexibility is lost in a short time. Particularly for an adherend surface having a step, if the follow-up adhesion of the adhesive sheet before and after curing is poor, the members may not be firmly joined. On the other hand, if the followability of the adhesive sheet before and after curing is improved, after joining the members through the adhesive sheet, when exposed to an environment with a large temperature change, the cured adhesive sheet may easily expand and contract with the temperature change. If the cured adhesive sheet easily expands and contracts with temperature, problems such as shrinkage causing peeling or displacement of the adhesive sheet from the adherend surface, generation of cracks or damage to the adherend between the adhesive sheet and the adherend, or elongation due to softening causing the adhesive sheet to protrude from the adherend surface may occur, and it becomes difficult to firmly and stably join and hold the members for a long time in an environment with a large temperature change.

[0008] The present disclosure has been made in view of the above problems, and provides an adhesive sheet that can be joined without being restricted by the light transmittance or heat resistance of an adherend, has high follow-up adhesion to the adherend surface, and has high cold and heat cycle characteristics, as well as a laminate using the adhesive sheet and a method for manufacturing the same.

Means for Solving the Problems

[0009] The present invention provides an adhesive sheet including an adhesive layer containing a photocurable resin (A) having a polymerizable functional group other than a polymerizable unsaturated double bond, a thermoplastic resin (B) having a polymerizable functional group other than a polymerizable unsaturated double bond, and a photopolymerization initiator (C), wherein the content of the thermoplastic resin (B) in the adhesive layer is within a predetermined range.

[0010] The present invention also provides a laminate having the above-described adhesive sheet, a first member bonded to the first main surface of the adhesive sheet, and a second member bonded to the second main surface of the adhesive sheet.

[0011] The present invention also provides a method for manufacturing a laminate using the above-described adhesive sheet, the method including: step [1] of bonding a first adherend to the first main surface of the adhesive sheet; step [2] of bonding a second adherend to the second main surface of the adhesive sheet; and step [3] of curing the adhesive sheet, and further including a step of irradiating the first main surface or the second main surface of the adhesive sheet with active energy rays before step [1] or between step [1] and step [2].

Effects of the Invention

[0012] According to the present invention, it is possible to provide an adhesive sheet that can be joined without being restricted by the light transmittance or heat resistance of an adherend, has high follow-up adhesion to the adherend surface, and has high cold and heat cycle characteristics, as well as a laminate using the adhesive sheet and a method for manufacturing the same.

Modes for Carrying Out the Invention

[0013] Hereinafter, the adhesive sheet of the present invention, the laminate using the same, and the manufacturing method thereof will be described.

[0014] 1. Adhesive sheet The adhesive sheet of the present invention includes an adhesive layer containing a photocurable resin (A) having a polymerizable functional group other than a polymerizable unsaturated double bond, a thermoplastic resin (B) having a polymerizable functional group other than a polymerizable unsaturated double bond, and a photopolymerization initiator (C), and the content of the thermoplastic resin (B) in the adhesive layer is within a predetermined range.

[0015] The adhesive sheet of the present invention can be joined without being restricted by the light transmittance and heat resistance of the adherend, has high follow-up adhesion to the adherend surface, and has high cold and heat cycle characteristics. Further, a laminate using the adhesive sheet and a manufacturing method thereof can be provided.

[0016] Specifically, in the adhesive sheet of the present invention, since the adhesive layer contains desired components, the curing reaction rate after light irradiation is slow and the reaction proceeds gradually. Therefore, in the adhesive sheet of the present invention, by irradiating light in advance to cause the curing reaction of the adhesive layer when joining members, the members can be bonded as long as the curing reaction is not completed. As a result, unlike ordinary photocurable and thermosetting adhesive sheets, the curing reaction proceeds without irradiating light or heating and pressurizing at a high temperature in a state where the members to be joined are laminated via the adhesive sheet. Therefore, the members can be easily and firmly joined without being restricted by the light transmittance and heat resistance of the adherend.

[0017] Further, in the adhesive sheet of the present invention, since the adhesive layer contains desired components, the curing reaction does not proceed rapidly after light irradiation but proceeds gradually, so that it can have flexibility even after light irradiation. Therefore, the adhesive sheet of the present invention can follow and adhere to the adherend surface, particularly the step of the adherend surface, before and after curing, and can exhibit a high adhesive force to the member.

[0018] Furthermore, in the adhesive sheet of the present invention, since the adhesive layer contains desired components in desired blending amounts, it has followability to the adherend even after curing and is less likely to undergo excessive expansion and contraction with temperature changes. For this reason, the members joined through the sheet of the present invention, even when placed in an environment with large temperature changes, are less likely to cause problems due to the expansion and contraction of the adhesive sheet, such as peeling of the adhesive layer from the members, positional deviation, generation of cracks, breakage of the members, and the softened adhesive layer protruding from the adherend surface, and can exhibit high cold and heat cycle resistance characteristics.

[0019] Hereinafter, each configuration of the adhesive sheet of the present invention will be described.

[0020] (1) Adhesive layer The adhesive layer in the present invention contains at least a photocurable resin (A) having a polymerizable functional group other than a polymerizable unsaturated double bond, a thermoplastic resin (B) having a polymerizable functional group other than a polymerizable unsaturated double bond, and a photoinitiator (C), and the content of the thermoplastic resin (B) is within a predetermined range.

[0021] The adhesive layer in the present invention contains a photocurable resin (A) and a thermoplastic resin (B), and these resins each have a polymerizable functional group other than a polymerizable unsaturated double bond. When the adhesive layer is irradiated with light, the polymerizable functional groups possessed by the photocurable resin (A) and the thermoplastic resin (B) are activated, and curing proceeds in a state where the reactivity is enhanced. For this reason, the above adhesive layer suppresses the rapid curing reaction after light irradiation and can cause the curing reaction to proceed gradually. Also, since the curing reaction after light irradiation proceeds gradually, it can have flexibility even after light irradiation, and joining of members becomes possible. That is, the adhesive layer in the present invention is a delayed-curing type adhesive layer.

[0022] The adhesive layer in the present invention is a layer composed of an adhesive composition containing at least a photocurable resin (A) having a polymerizable functional group other than a polymerizable unsaturated double bond, a thermoplastic resin (B) having a polymerizable functional group other than a polymerizable unsaturated double bond, and a photoinitiator (C), and the content of the thermoplastic resin (B) is within a predetermined range. That is, the total amount of the adhesive layer refers to the total amount of the adhesive composition constituting the adhesive layer, and the content in the adhesive layer refers to the content in the total amount of the adhesive composition constituting the adhesive layer. It should be noted that the total amount of the adhesive composition does not include a solvent.

[0023] <Thermoplastic resin (B)> In the present invention, the content of the thermoplastic resin (B) in the adhesive layer is in the range of 15% by mass to 50% by mass. By the content of the thermoplastic resin (B) being within the above range, it is possible to impart flexibility that can ensure the followability of the adhesive layer to the adherend even after light irradiation, and the cured adhesive layer is less likely to expand and contract with temperature changes while having followability to the adherend, so that it is possible to hardly cause problems due to the expansion and contraction of the adhesive sheet. Among them, by making the ratio of the thermoplastic resin (B) lower than that of the photocurable resin (A), excellent adhesive reliability after curing can be obtained, and further excellent adhesiveness at high temperatures can be obtained.

[0024] The content of the above-mentioned thermoplastic resin (B) may be in the range of 15% by mass to 50% by mass in the total amount of the adhesive layer, in other words, in the total amount of the adhesive composition. However, it is preferably in the range of 25% by mass to 50% by mass, more preferably in the range of 25% by mass to 45% by mass, still more preferably in the range of 30% by mass to 45% by mass, and particularly preferably in the range of 34% by mass to 45% by mass. It is possible to achieve both good followability to the adherend and cold and heat cycle resistance characteristics, and furthermore, excellent adhesion reliability after curing and excellent adhesiveness at high temperatures can be obtained. In addition, when the content of the thermoplastic resin (B) is excessive compared to the above range, the adhesive layer may be easily deformed and stretched at high temperatures, or the heat resistance of the cured product may deteriorate. On the other hand, when it is less than the above range, the step followability to the adherend may deteriorate, or the proportion of the high molecular weight component in the entire adhesive layer may decrease, and it may not be possible to process it into a sheet shape.

[0025] Moreover, the ratio of the content of the thermoplastic resin (B) to the total of the content of the photocurable resin (A) and the content of the thermoplastic resin (B) in the above-mentioned adhesive layer is preferably in the range of 25% by mass to 68% by mass, more preferably in the range of 25% by mass to 60% by mass, in the range of 30% by mass to 60% by mass, in the range of 30% by mass to 55% by mass, in the range of 30% by mass to 50% by mass, and in the range of 35% by mass to 50% by mass. By setting the ratio of the content of the thermoplastic resin (B) to the total of the content of the photocurable resin (A) and the content of the thermoplastic resin (B) in the adhesive layer within the above range, it is possible to impart flexibility that can ensure the followability of the adhesive layer to the adherend even after light irradiation. In addition, since the cured adhesive layer has appropriate flexibility, it can follow the adherend and is less likely to expand and contract with temperature changes, so it is possible to hardly cause problems due to the expansion and contraction of the adhesive sheet.

[0026] The ratio of the content of the thermoplastic resin (B) to the total of the content of the photocurable resin (A) and the content of the thermoplastic resin (B) can be calculated by the following formula. <Formula> Ratio of the content of the thermoplastic resin (B) to the sum of the content of the photocurable resin (A) and the content of the thermoplastic resin (B) = {Content of the thermoplastic resin (B) in the adhesive layer [parts by mass] / (Content of the photocurable resin (A) in the adhesive layer [parts by mass] + Content of the thermoplastic resin (B) in the adhesive layer [parts by mass])} × 100 [mass%]

[0027] The thermoplastic resin (B) in the present invention has a polymerizable functional group other than a polymerizable unsaturated double bond. By including the thermoplastic resin (B) in the adhesive layer in the present invention, it can react with the photocurable resin (A) mutually, suppress the rapid curing reaction after light irradiation, and make it possible to gradually progress the curing reaction. Thereby, the adhesive layer in the present invention can have flexibility even after light irradiation, can follow and adhere closely to the adherend surface of the member after light irradiation, and has appropriate flexibility even after curing, so that two members can be firmly joined via the adhesive layer.

[0028] As the polymerizable functional group other than the polymerizable unsaturated double bond that the thermoplastic resin (B) has, it is preferable to have at least one selected from the group consisting of an isocyanate group, a hydroxyl group, an oxetanyl group, and an epoxy group. By using the thermoplastic resin (B) having at least one selected from the group consisting of the isocyanate group, the hydroxyl group, the oxetanyl group, and the epoxy group, it becomes possible to react with the photocurable resin (A) mutually, and suppress the rapid curing reaction after light irradiation and make it possible to gradually progress the curing reaction. Thereby, the adhesive layer in the present invention can have flexibility even after light irradiation, the follow-up adhesion to the adherend surface is further enhanced, and also has appropriate flexibility even after curing, so that two members can be firmly joined via the adhesive layer.

[0029] Examples of the thermoplastic resin (B) include polyester resins, polyurethane resins, acrylic resins, polyvinyl acetal resins, epoxy resins (thermoplastic epoxy resins), etc., which have polymerizable functional groups other than polymerizable unsaturated double bonds. These thermoplastic resins may be homopolymers or copolymers. Further, these thermoplastic resins may be used alone or in combination of two or more.

[0030] The polyurethane resin having a polymerizable functional group other than a polymerizable unsaturated double bond is preferably a polyurethane resin (B') having at least one selected from the group consisting of an isocyanate group, a hydroxyl group, an oxetanyl group, and an epoxy group.

[0031] The above polyurethane resin (B') can be obtained, for example, by reacting a polyol (b'1) with a polyisocyanate (b'2).

[0032] The polyol (b'1) preferably has a number average molecular weight in the range of 500 to 5000, and more preferably has a number average molecular weight in the range of 1000 to 3000 in order to obtain an adhesive layer excellent in shape retention, coating workability, initial cohesion, etc. The above number average molecular weight is a value measured under the following conditions.

[0033] The measurement of the number average molecular weight described in this specification is a value measured under the following conditions by gel permeation chromatography (GPC) in terms of polystyrene. (Conditions) · Resin sample solution: 0.4 mass% tetrahydrofuran (THF) solution · Measuring device model number: HLC-8220GPC (manufactured by Tosoh Corporation) · Column: TSKgel (manufactured by Tosoh Corporation) · Eluent: Tetrahydrofuran (THF)

[0034] As such a polyol (b'1), for example, one or more selected from the group consisting of polyester polyol, polycarbonate polyol, and polyether polyol can be preferably used.

[0035] Among them, in the present invention, as the polyol (b'1), it is preferable to use at least one or two or more of polyester polyol and polycarbonate polyol, and it is more preferable to use at least one or two or more of polyester polyol. A more preferable example is that as the polyol (b'1), it is preferable to use two or more polyester polyols. Another preferable example is that as the polyol (b'1), it is preferable to use one or two or more polyester polyols and one or two or more polycarbonate polyols. Also, in another preferable example, as the polyol (b'1), it is preferable to use one or two or more polyester polyols and one or two or more polyether polyols. By using different polyester polyols in combination, or by using a polyester polyol and other polyols in combination, the adhesive sheet of the present invention has a more stable sheet shape before curing, improved handleability, and improved follow-up adhesion to the unevenness of the adherend surface.

[0036] The proportion of the total amount of the polyol selected from polyester polyol, polycarbonate polyol, and polyether polyol in the above polyol (b'1) is preferably 20% by mass or more, more preferably 50% by mass or more, and particularly preferably 100% by mass in the total amount of the above polyol (b'1). This is because the adhesive layer containing the polyurethane resin (B') can maintain an adhesive property at a level that can be adhered at room temperature, and the follow-up adhesion to the adherend surface can be further improved.

[0037] When the above polycarbonate polyol and the above polyester polyol are used in combination, the mass ratio of the polycarbonate polyol to the polyester polyol (polycarbonate polyol / polyester polyol) is preferably in the range of 0.4 to 7.0, more preferably in the range of 1.0 to 2.0. This is because a polyurethane resin having a loss tangent value within a desired range can be obtained, the handleability before curing is excellent, and an adhesive layer having higher follow-up adhesion to the adherend surface can be formed. Further, when the above polyether polyol and the above polyester polyol are used in combination, the mass ratio of the polyether polyol to the polyester polyol (polyether polyol / polyester polyol) can also be set within the same range as described above.

[0038] Examples of the above polyester polyol include those obtained by subjecting a low molecular weight polyol and a polycarboxylic acid to an esterification reaction, polyesters obtained by subjecting a cyclic ester compound such as ε-caprolactone to a ring-opening polymerization reaction, and copolymer polyesters thereof.

[0039] Examples of the above low molecular weight polyol include aliphatic alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, 1,3-butanediol, etc., and cyclohexanedimethanol, etc., each having a molecular weight of approximately 50 to 300.

[0040] Examples of the above polycarboxylic acid that can be used in the production of the above polyester polyol include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and anhydrides or esterified products thereof.

[0041] As the above polyester polyol, it is preferable to use an aliphatic polyester polyol, and more preferably to use a linear aliphatic polyester polyol. This is because a polyurethane resin (B') having a loss tangent value within a desired range can be obtained, the handleability before curing is excellent, and an adhesive layer having higher follow-up adhesion to the adherend surface can be formed. The above linear aliphatic polyester polyol refers to a polyester polyol having no alkyl group in the side chain.

[0042] Examples of the above aliphatic polyester polyol include those obtained by reacting the above aliphatic alkylene glycol and aliphatic dicarboxylic acid, and it is preferable to use an aliphatic polyester polyol obtained by subjecting 1,6 - hexanediol and adipic acid to an esterification reaction.

[0043] Also, as the above polyester polyol, it is preferable to use an aromatic polyester polyol. This is because the elastic modulus of the polyurethane resin (B') can be increased to improve rigidity, and it becomes possible to suppress joint displacement, warping, and deformation over time before and after curing of the adhesive layer. Examples of the above aromatic polyester polyol include those obtained by reacting an aromatic polyol and an aliphatic or aromatic dicarboxylic acid, and for example, an aromatic polyester polyol obtained by reacting an ethylene oxide adduct of bisphenol A with phthalic acid and adipic acid is preferably used.

[0044] The above polyester polyol may use only aliphatic polyester polyol, may use only aromatic polyester polyol, or may use both aliphatic polyester polyol and aromatic polyester polyol in combination. Among them, it is preferable that the above polyester polyol uses both aliphatic polyester polyol and aromatic polyester polyol in combination, that is, the above polyester polyol uses one or more aromatic polyester polyols and one or more aliphatic polyester polyols. An adhesive layer containing a polyurethane resin (B') prepared by combining an aromatic polyester polyol and an aliphatic polyester polyol can achieve a balance between the hardness and softness of the layer before and after curing, exhibit high follow-up adhesion to the adherend surface, suppress joint displacement, warping, and deformation of the adhesive layer over time, and improve the cold and heat cycle resistance characteristics. Therefore, in order to balance the contradictory physical properties such as the hardness and softness of the adhesive layer, the content ratio of the aromatic polyester polyol and the aliphatic polyester polyol (aromatic polyester polyol / aliphatic polyester polyol) is preferably in the range of 20 / 80 to 90 / 10 by mass ratio, and more preferably in the range of 50 / 50 to 80 / 20.

[0045] The above polyester polyol preferably has a number average molecular weight in the range of 1000 to 5000. This is because a polyurethane resin (B') having a loss tangent value within a desired range can be obtained, the handleability before curing is excellent, and an adhesive layer with higher follow-up adhesion to the adherend surface can be obtained.

[0046] In particular, when using a polyester polyol obtained by reacting an aliphatic diol such as 1,2-ethanediol or 1,4-butanediol with adipic acid as the polyester polyol, it is preferable to use one having a number average molecular weight in the range of 1100 to 2900. When using a polyester polyol obtained by reacting 1,6-hexanediol with adipic acid, it is preferable to use one having a number average molecular weight in the range of 1100 to 5000. When using a polyester polyol obtained by reacting 1,6-hexanediol with sebacic acid, it is preferable to use one having a number average molecular weight in the range of 1000 to 5000.

[0047] When the polyol (b'1) contains a polyester polyol and a polyol other than the polyester polyol, the polyester polyol can be used in the range of 10% to 90% by mass based on the total amount of the polyol (b'1). Among them, it is preferably used in the range of 10% to 80% by mass, more preferably in the range of 20% to 80% by mass, still more preferably in the range of 30% to 70% by mass, and even more preferably in the range of 40% to 50% by mass. This is because the adhesive layer containing the polyurethane resin (B') can maintain an adhesiveness level that can be adhered at room temperature, and the follow-up adhesion to the adherend surface can be further improved.

[0048] As the above polycarbonate polyol, for example, those obtained by reacting a carbonic acid ester and / or phosgene with a low molecular weight polyol can be used. As the above carbonic acid ester, for example, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclo carbonate, diphenyl carbonate, etc. can be used.

[0049] Examples of the low-molecular polyol capable of reacting with the above carbonic ester or phosgene include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcinol, bisphenol A, bisphenol F, 4,4'-biphenol, etc.

[0050] Moreover, as the polycarbonate polyol, it is preferable to use an aliphatic polycarbonate polyol or an alicyclic polycarbonate polyol.

[0051] As the aliphatic polycarbonate polyol, those obtained by reacting a dialkyl carbonate with one or more polyols selected from the group consisting of 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol and 1,6-hexanediol are preferably used. This is because the adhesive layer containing the polyurethane resin (B') can have an adhesiveness level that allows for sticking at room temperature.

[0052] As the alicyclic polycarbonate polyol, for example, those obtained by reacting a dialkyl carbonate with one or more polyols selected from the group consisting of cyclohexanedimethanol and its derivatives are preferably used. This is because the adhesive layer containing the polyurethane resin (B') can have adhesiveness at a level that allows for sticking at room temperature and excellent initial cohesion.

[0053] The above polycarbonate polyol preferably has a number average molecular weight in the range of 500 to 5000, and more preferably has a number average molecular weight in the range of 800 to 3000. This is because a polyurethane resin (B') with a loss tangent value within the desired range can be obtained, the handleability before curing is excellent, and an adhesive layer with higher follow-up adhesion to the adherend surface can be formed.

[0054] When the above polyol (b'1) contains the above polycarbonate polyol and a polyol other than the above polycarbonate polyol, the above polycarbonate polyol can be used in the range of 10% to 80% by mass based on the total amount of the above polyol (b'1), preferably in the range of 20% to 80% by mass, more preferably in the range of 30% to 70% by mass, and preferably in the range of 40% to 50% by mass. This is because the adhesive layer containing the polyurethane resin (B') can maintain adhesiveness at a level that allows for sticking at room temperature, and the follow-up adhesion to the adherend surface can be further improved.

[0055] Examples of the above polyether polyol include those obtained by addition polymerization of an alkylene oxide using one or more compounds having two or more active hydrogen atoms as an initiator.

[0056] As the above initiator, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3 - butanediol, 1,4 - butanediol, 1,6 - hexanediol, bisphenol A, glycerin, trimethylolethane, trimethylolpropane, etc. can be used.

[0057] As the above alkylene oxide, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, etc. can be used.

[0058] As the above polyether polyol, it is preferable to use an aliphatic polyether polyol or a polyether polyol having an alicyclic structure.

[0059] As the above polyether polyol, in particular, polytetramethylene glycol obtained by ring - opening polymerization of tetrahydrofuran, a polytetramethylene glycol derivative obtained by reacting tetrahydrofuran with an alkyl - substituted tetrahydrofuran, a polytetramethylene glycol derivative obtained by copolymerizing neopentyl glycol and tetrahydrofuran, etc. can be used. Among them, as the above polyether polyol, in order to maintain the adhesiveness at a level possible at room temperature for the adhesive sheet containing the above adhesive layer and to improve excellent flexibility, durability (especially hydrolysis resistance), etc., it is preferable to use polytetramethylene glycol (PTMG) and polytetramethylene glycol derivative (PTXG).

[0060] In addition to the above, as the above polyol (b'1), other polyols can be used. Examples of the above other polyols include acrylic polyols.

[0061] As the polyisocyanate (b'2), an alicyclic polyisocyanate, an aliphatic polyisocyanate, an aromatic polyisocyanate, etc. can be used, and it is preferable to use an alicyclic polyisocyanate.

[0062] Examples of the alicyclic polyisocyanate include isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, 2,4- and / or 2,6-methylcyclohexane diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexylene-1,2-dicarboxylate, 2,5- and / or 2,6-norbornane diisocyanate, dimer acid diisocyanate, bicycloheptane triisocyanate, etc., which can be used alone or in combination of two or more.

[0063] Among the above-mentioned alicyclic polyisocyanates, in order to obtain an adhesive sheet having good reactivity with the above polyol (b'1) and excellent heat resistance, light transmittance, etc., it is preferable to use 4,4'-dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane (BICH).

[0064] As a method for producing a polyurethane resin (B') having an isocyanate group by reacting the above polyol (b'1) and the above polyisocyanate (b'2), for example, the above polyol (b'1) charged into a reaction vessel is heated under normal pressure or reduced pressure conditions to remove moisture, and then the above polyisocyanate (b'2) is supplied all at once or in portions and reacted.

[0065] The reaction between the above polyol (b'1) and the above polyisocyanate (b'2) is preferably carried out in a range where the equivalent ratio of the isocyanate groups in the above polyisocyanate (b'2) to the hydroxyl groups in the above polyol (b'1) (hereinafter referred to as [NCO / OH equivalent ratio]) is in the range of 1.1 to 20.0, more preferably in the range of 1.1 to 13.0, even more preferably in the range of 1.1 to 5.0, and particularly preferably in the range of 1.5 to 3.0.

[0066] The reaction conditions (temperature, time, etc.) for the above polyol (b'1) and the above polyisocyanate (b'2) may be appropriately set in consideration of various conditions such as safety, quality, and cost, and are not particularly limited. For example, the reaction temperature is preferably in the range of 70 to 120 °C, and the reaction time is preferably in the range of 30 minutes to 5 hours.

[0067] When reacting the above polyol (b'1) and the above polyisocyanate (b'2), if necessary, a catalyst such as a tertiary amine catalyst or an organometallic catalyst can be used.

[0068] Also, the above reaction may be carried out in a solvent-free environment or in the presence of an organic solvent. Examples of the above organic solvent include ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate, ketone solvents such as acetone, methyl ethyl ketone, methyl butyl ketone, and cyclohexanone, ether ester solvents such as methyl cellosolve acetate and butyl cellosolve acetate, aromatic hydrocarbon solvents such as toluene and xylene, and amide solvents such as dimethylformamide and dimethylacetamide, which can be used alone or in combination of two or more. The above organic solvent may be removed by an appropriate method such as heating under reduced pressure or drying at normal pressure during the production of the above polyurethane resin (B') or after the production of the above polyurethane resin (B').

[0069] As the polyurethane resin (B’) having an isocyanate group, for example, a polyurethane resin (B’1) having an isocyanate group obtained by reacting a polyol (b’1) and a polyisocyanate (b’2) can be used. Regarding the details (types, formulations, etc.) of the polyol (b’1) and the polyisocyanate (b’2) used in the preparation of the polyurethane resin (B’) having an isocyanate group, they can be the same as the details of the above-described polyol (b’1) and polyisocyanate (b’2).

[0070] As the polyurethane resin (B’) having a hydroxyl group, for example, a polyurethane resin (B’2) having a hydroxyl group obtained by reacting a polyol (b’1) and a polyisocyanate (b’2) can be used. Regarding the details (types, formulations, etc.) of the polyol (b’1) and the polyisocyanate (b’2) used in the preparation of the polyurethane resin (B’) having a hydroxyl group, they can be the same as the details of the above-described polyol (b’1) and polyisocyanate (b’2).

[0071] As the polyurethane resin (B’) having an oxetanyl group or an epoxy group, for example 1) A polyurethane (B’1) having an isocyanate group, 2) A monomer (B”) having a functional group (b”1) capable of reacting with an isocyanate group, an oxetanyl group or an epoxy group, and a polymerizable functional group (b”2) other than one or more polymerizable unsaturated double bonds, and the polyurethane resin (B’3) obtained by reacting them can be used.

[0072] As the functional group (b”1) capable of reacting with the above isocyanate group, for example, a hydroxyl group, an amino group, a carboxyl group, a mercapto group, etc. can be used, and among them, it is preferable to use a hydroxyl group and an amino group.

[0073] The polymerizable functional group (b”2) other than the above-mentioned polymerizable unsaturated double bond refers to those other than the so-called radically polymerizable functional groups, such as functional groups having cationic polymerizability, functional groups having anionic polymerizability, etc. Examples thereof include epoxy groups, oxetanyl groups, ethylene sulfide groups, etc.

[0074] The monomer (B”) is not particularly limited as long as it has the functional group (b”1) and the polymerizable functional group (b”2). Examples thereof include 3-ethyl-3-(4-hydroxybutyl)oxymethyl-oxetane, 3-hydroxymethyl-3-ethyloxetane, 2-hydroxymethyloxetane, 3-hydroxyoxetane, etc.

[0075] The monomer (B”) is preferably used in the range of 5 parts by mass to 20 parts by mass, more preferably in the range of 5 parts by mass to 15 parts by mass, based on 100 parts by mass of the polyurethane resin (B’1).

[0076] More specifically, as the monomer (B”), an amount capable of supplying a functional group capable of reacting with the isocyanate group, preferably exceeding 50 mol% and not exceeding 100 mol%, more preferably 60 mol% to 100 mol%, still more preferably 80 mol% to more than the number of moles of the isocyanate group possessed by the polyurethane resin (B’1). 100 mol% can be used. Thereby, a polyurethane resin excellent in appropriate flexibility, rapid curability, shape retention after coating on a substrate, mechanical strength, durability (particularly hydrolysis resistance), and follow-up adhesion to an adherend surface can be obtained.

[0077] When reacting the above polyurethane resin (B’1) with the above monomer (B”), a urethanization catalyst can be used as needed. The above urethanization catalyst can be appropriately added at any stage of the above urethanization reaction. The above urethanization reaction is preferably carried out until the isocyanate group content (%) becomes substantially constant. Examples of the above urethanization catalyst include nitrogen-containing compounds such as triethylamine, triethylenediamine, and N-methylmorpholine, organic metal salts such as potassium acetate, zinc stearate, and stannous octylate, and organic metal compounds such as dibutyltin dilaurate.

[0078] In addition, the thermoplastic epoxy resin having a polymerizable functional group other than the polymerizable unsaturated double bond is a polymer or copolymer of epoxy compounds having a linear structure, or a copolymer of an epoxy compound and a monomer copolymerizable with this epoxy compound having a linear structure. Specifically, bisphenol A type epoxy resin, bisphenol fluorene type epoxy resin, cresol novolak type epoxy resin, phenol novolak type epoxy resin, cycloaliphatic type epoxy resin, long-chain aliphatic type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, etc. can be mentioned, and bisphenol A type epoxy resin and bisphenol fluorene type epoxy resin are preferred.

[0079] Among them, the adhesive layer in the present invention preferably contains, as the thermoplastic resin (B), one or more resins selected from the group consisting of a polyurethane resin, an acrylic resin, and an epoxy resin, which have a polymerizable functional group other than a polymerizable unsaturated double bond, and preferably contains at least one or more polyurethane resins having a polymerizable functional group other than a polymerizable unsaturated double bond. By using a polyurethane resin having a polymerizable functional group other than a polymerizable unsaturated double bond as the thermoplastic resin (B), it is possible to suppress a rapid curing reaction after light irradiation and gradually progress the curing reaction, so that it can have the flexibility required for bonding even after light irradiation. As a result, the adhesive layer in the present invention can closely adhere to the adherend surface of the member after light irradiation, and also has appropriate flexibility after curing, so that the members can be firmly joined via the adhesive layer.

[0080] The above thermoplastic resin (B) preferably has a loss tangent (tanδ 40 ) of 3 or less at a frequency of 1.0 Hz and a temperature of 40 °C before curing, more preferably 0.001 or more and 2.0 or less, still more preferably 0.001 or more and 1.0 or less, and even more preferably 0.001 or more and 0.9 or less. By setting the loss tangent of the thermoplastic resin (B) at a frequency of 1.0 Hz and a temperature of 40 °C within the above range, when the adhesive sheets before curing are laminated and stored, the sheet thickness does not change and they can be stored without shape change.

[0081] Further, the above thermoplastic resin (B) preferably has a loss tangent (tanδ 60 ) of 1 or more at a frequency of 1.0 Hz and a temperature of 60 °C before curing, more preferably 1.2 or more and 20 or less, still more preferably 1.3 or more and 15 or less, and even more preferably 1.5 or more and 15 or less. By setting the loss tangent of the thermoplastic resin (B) at a frequency of 1.0 Hz and a temperature of 60 °C within the above range, the followability to the adherend is excellent.

[0082] The loss tangent of the thermoplastic resin (B) at each temperature (40 °C, 60 °C) with a frequency of 1.0 Hz is obtained by molding the thermoplastic resin (B) before curing with a thickness of 1 mm into a circular shape with a diameter of 8 mm and cutting it to prepare a test piece. Using a dynamic viscoelasticity tester (manufactured by Rheometric Scientific, trade name: ARES 2KSTD), the test piece is sandwiched between parallel disks, which are the measurement part of the tester, and the storage elastic modulus (G') and loss elastic modulus (G") at each temperature with a frequency of 1.0 Hz are measured. It is the value (G" / G') obtained by dividing the above loss elastic modulus (G") by the above storage elastic modulus (G').

[0083] The loss tangent (tanδ) of the thermoplastic resin (B) at each temperature can be adjusted, for example, when using a urethane resin as the thermoplastic resin (B), by appropriately selecting the composition such as polyol and polyisocyanate constituting the urethane resin and its number average molecular weight, etc.

[0084] The melting point of the thermoplastic resin (B) is preferably in the range of 30 °C to 120 °C, more preferably in the range of 35 °C to 100 °C, and even more preferably in the range of 40 °C to 80 °C. By using the thermoplastic resin (B) having a melting point within the above range, the adhesive sheet of the present invention has a more stable sheet shape before curing, improved handleability, and can also improve the follow-up adhesion to the adherend surface.

[0085] The melting point of the thermoplastic resin (B) refers to the temperature indicating the maximum exothermic peak (exothermic peak top) observed when measuring using the differential scanning calorimetry (DSC method), heating from 20 °C to 150 °C under a heating rate of 10 °C / min, holding for 1 minute, then once cooling to -10 °C under a cooling rate of 10 °C / min, holding for 10 minutes, and then measuring again under a heating rate of 10 °C / min.

[0086] The above-mentioned thermoplastic resin (B) preferably has a weight-average molecular weight in the range of 5,500 to 2,000,000, more preferably in the range of 5,500 to 1,000,000, and even more preferably in the range of 5,500 to 800,000. By setting the weight-average molecular weight of the thermoplastic resin (B) within the above range, the sheet shape before curing becomes more stable, the handleability is improved, and the follow-up adhesion to the adherend surface can be enhanced. If the weight-average molecular weight of the thermoplastic resin (B) is too small, the cohesive force of the adhesive layer before curing is insufficient, and bleeding of the adhesive layer may occur over time, making the handleability likely to deteriorate. On the other hand, if the weight-average molecular weight of the thermoplastic resin (B) is too large, the compatibility with the photocurable resin (A) may decrease, making the reaction difficult to proceed.

[0087] The measurement of the weight-average molecular weight described in this specification is a value measured by gel permeation chromatography (GPC) in terms of polystyrene under the following conditions. (Conditions) · Resin sample solution: 0.4 mass% tetrahydrofuran (THF) solution · Measuring device model number: HLC-8220GPC (manufactured by Tosoh Corporation) · Column: TSKgel (manufactured by Tosoh Corporation) · Eluent: Tetrahydrofuran (THF)

[0088] <Photocurable resin (A)> The photocurable resin (A) has a polymerizable functional group other than the polymerizable unsaturated double bond. By including the photocurable resin (A) in the adhesive layer in the present invention, polymerization occurs due to the polymerizable functional group of the photocurable resin (A) by light irradiation, and further polymerization proceeds even in the dark reaction or at low temperatures. Therefore, it is possible to join the members without being restricted by the light transmittance and heat resistance of the members.

[0089] Examples of the photocurable resin (A) include photopolymerizable compounds such as radical photopolymerizable compounds, cationic photopolymerizable compounds, and anionic photopolymerizable compounds. Among them, cationic photopolymerizable compounds and / or anionic photopolymerizable compounds are preferred. In other words, it is preferable that the photocurable resin (A) has a cationic photopolymerizable functional group and / or an anionic photopolymerizable functional group as a polymerizable functional group other than the polymerizable unsaturated double bond. By including a polymerizable compound having these functional groups in the adhesive layer, it becomes less susceptible to inhibition by oxygen during curing, and a continuous reaction is likely to proceed even after light irradiation. Therefore, the members can be joined without being limited by the light transmittance and heat resistance of the members. In particular, a cationic photopolymerizable compound is more preferable because of its excellent reactivity after light irradiation and easy obtainment of high adhesiveness after curing. The above photopolymerizable compounds may be used alone or in combination.

[0090] The above cationic photopolymerizable compound only needs to have one or more cationic photopolymerizable functional groups in one molecule, and is not particularly limited. The cationic photopolymerizable compound preferably has one or more cationic photopolymerizable functional groups such as epoxy group, oxetanyl group, hydroxyl group, vinyl ether group, episulfide group, ethyleneimine group, and oxazoline group in one molecule. Among them, in order to obtain high curability and adhesiveness after curing, the cationic photopolymerizable compound preferably has an epoxy group or an oxetanyl group.

[0091] As the photocationic polymerizable compound having an epoxy group, a compound having one or more epoxy groups in one molecule can be used. Specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, polyhydroxynaphthalene type epoxy resin, isocyanate-modified epoxy resin, 10-(2,5-dihydroxyphenyl)-9,10-dihydro 9-oxa-10-phosphaphenanthrene-10-oxide modified epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, hexanediol type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, phenol aralkyl type epoxy resin, naphthol novolac type epoxy resin, naphthol aralkyl type epoxy resin, naphthol-phenol co-condensed novolac type epoxy resin, naphthol-cresol co-condensed novolac type epoxy resin, aromatic hydrocarbon formaldehyde resin-modified phenol resin type epoxy resin, biphenyl-modified novolac type epoxy resin, trimethylolpropane type epoxy resin, alicyclic epoxy resin, acrylic resin having an epoxy group, polyurethane resin having an epoxy group, polyester resin having an epoxy group, flexible epoxy resin, etc. can be used.

[0092] Among them, it is preferable to use at least one of an alicyclic epoxy resin and a polyfunctional aliphatic type epoxy resin, and it is more preferable to use an alicyclic epoxy resin. Since these are excellent in photocationic polymerizability, an adhesive sheet excellent in curability can be obtained, and a suitable elastic modulus for suppressing the deformation of the adhesive layer over time after bonding can be imparted.

[0093] Furthermore, the epoxy resin may be a modified product. This is because by blending or adding other resin components or the like to the epoxy resin, the flexibility of the adhesive layer can be increased and the adhesive strength and bending strength can be improved. As such modified products, CTBN (carboxyl-terminated butadiene-acrylonitrile rubber) modified epoxy resin; epoxy resin in which various rubbers such as acrylic rubber, NBR, SBR, butyl rubber, or isoprene rubber are dispersed in the resin; epoxy resin modified with a liquid rubber as described above; epoxy resin to which various resins such as acrylic, urethane, urea, polyester, and styrene are added; chelate modified epoxy resin; polyol modified epoxy resin, etc. can be used.

[0094] On the other hand, examples of the oxetanyl group-containing cationic photopolymerizable compound include oxetane compounds such as 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,4-bis[(3-methyl-3-oxetanylmethoxy)methyl]benzene, 3-methyl-3-glycidyloxetane, 3-ethyl-3-glycidyloxetane, 3-methyl-3-hydroxymethyloxetane, 3-ethyl-3-hydroxymethyloxetane, and di{1-ethyl(3-oxetanyl)}methyl ether.

[0095] In the adhesive layer of the present invention, as the photocurable resin (A), it is preferable to use a photocurable resin (a1) in which the temperature (Tg-tanδ) at which the loss tangent after curing shows a maximum value is 100°C or higher. This is because high heat resistance can be imparted to the cured adhesive sheet, and particularly the heat cycle resistance characteristics at high temperatures are excellent. Among them, for the photocurable resin (a1), the temperature at which the loss tangent after curing shows a maximum value is preferably 105°C or higher, 110°C or higher, 115°C or higher, and the above temperature is preferably 250°C or lower, particularly 230°C or lower, 200°C or lower. The temperature (Tg-tanδ) at which the loss tangent after curing of the photocurable resin (a1) shows a maximum value is a value measured at a frequency of 1.0 Hz using a dynamic viscoelasticity measuring device (manufactured by Rheometric Scientific, trade name: RSA-II) for a cured product obtained by curing the epoxy resin alone.

[0096] As the photocurable resin (a1) in which the temperature (Tg-tanδ) at which the loss tangent after curing shows a maximum value is 100°C or higher, for example, an epoxy resin that is solid at room temperature (hereinafter referred to as a room-temperature solid epoxy resin) can be mentioned. Note that room temperature means 25°C.

[0097] Specific examples of the room-temperature solid epoxy resin that is the photocurable resin (a1) in which the temperature (Tg-Tanδ) at which the loss tangent after curing shows a maximum value is 100°C or higher include bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, polyhydroxynaphthalene type epoxy resin, isocyanate-modified epoxy resin, 10-(2,5-dihydroxyphenyl)-9,10-dihydro 9-oxa-10-phosphaphenanthrene-10-oxide modified epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, hexanediol type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, phenol aralkyl type epoxy resin, naphthol novolac type epoxy resin, naphthol aralkyl type epoxy resin, naphthol-phenol co-condensed novolac type epoxy resin, naphthol-cresol co-condensed novolac type epoxy resin, aromatic hydrocarbon formaldehyde resin-modified phenol resin type epoxy resin, biphenyl-modified novolac type epoxy resin, and the like.

[0098] In addition, when the photocurable resin (A) in the present invention is an epoxy resin, it is preferable to use both an epoxy resin that is solid at room temperature and an epoxy resin that is liquid at room temperature (hereinafter referred to as a room-temperature liquid epoxy resin). In other words, as the photocurable resin (A), it is preferably contained at least one or more kinds of room-temperature solid epoxy resins. Among them, it is preferable to include one or more kinds of room-temperature solid epoxy resins and one or more kinds of room-temperature liquid epoxy resins (hereinafter referred to as room-temperature liquid epoxy resins). By including a room-temperature solid epoxy resin and a room-temperature liquid epoxy resin as the photocurable resin (A), the adhesive layer can be easily processed into a sheet shape, and an appropriate adhesiveness can be imparted to the sheet before curing, making it easy to bond with the adherend. Also, by using a combination of a room-temperature solid epoxy resin and a room-temperature liquid epoxy resin, excellent adhesive reliability after curing can be obtained. Furthermore, by using a polyfunctional epoxy resin such as a novolac-type epoxy resin as the room-temperature solid epoxy resin in combination with a room-temperature liquid epoxy resin, excellent adhesiveness at high temperatures can be obtained.

[0099] The room-temperature liquid epoxy resin is not particularly limited as long as it is liquid at room temperature. Specifically, examples include trimethylolpropane-type epoxy resins, alicyclic epoxy resins, acrylic resins having an epoxy group, polyurethane resins having an epoxy group, polyester resins having an epoxy group, and the like. Among them, alicyclic epoxy resins are preferred.

[0100] The proportion of the photocurable resin (a1) in the photocurable resin (A) where the temperature (Tg-Tanδ) at which the loss tangent after curing shows a maximum value is 100°C or higher is preferably in the range of 20% by mass to 80% by mass, more preferably in the range of 30% by mass to 70% by mass, still more preferably in the range of 35% by mass to 65% by mass, and even more preferably in the range of 40% by mass to 65% by mass. Further, when the photocurable resin (A) is an epoxy resin, the proportion of the room-temperature solid epoxy resin in the total amount of the epoxy resin is preferably in the range of 20% by mass to 80% by mass, more preferably in the range of 30% by mass to 70% by mass, still more preferably in the range of 35% by mass to 65% by mass, and even more preferably in the range of 40% by mass to 65% by mass. This is because while the heat resistance of the cured sheet can be imparted, the curing time can be completed in a relatively short time. The proportion of the room-temperature solid epoxy resin in the total amount of the epoxy resin can be calculated by the following formula. <Formula> Proportion of room-temperature solid epoxy resin in total amount of epoxy resin = (Content of room-temperature solid epoxy resin [parts by mass] / Total amount of epoxy resin [parts by mass]) × 100 [mass%]

[0101] The content of the photocurable resin (A) in the adhesive layer in the present invention is preferably in the range of 10% by mass to 84% by mass, more preferably in the range of 20% by mass to 70% by mass, still more preferably in the range of 25% by mass to 65% by mass, even more preferably in the range of 30% by mass to 60% by mass, and most preferably in the range of 30% by mass to 50% by mass in the total amount of the adhesive layer, in other words, in the total solid content of the adhesive composition. By setting the content of the photocurable resin (A) in the adhesive layer in the above range, the follow-up adhesion to the step of the adherend surface is further enhanced, and the two members can be firmly joined through the cured adhesive layer. When the content of the photocurable resin (A) is excessive compared to the above range, it may not be possible to process it into a sheet form. On the other hand, when it is less than the above range, the heat resistance of the cured adhesive layer may deteriorate.

[0102] The above photocurable resin (A) preferably has a weight average molecular weight in the range of 100 to 5000, more preferably in the range of 150 to 3000, and even more preferably in the range of 200 to 2500. By setting the weight average molecular weight of the photocurable resin (A) within the above range, the sheet shape before curing becomes more stable, the handleability is improved, and the follow-up adhesion to the adherend surface can be increased. If the weight average molecular weight of the photocurable resin (A) is too small, the cohesive force of the adhesive layer before curing is insufficient, and the handleability may easily decrease, such as bleeding of the adhesive layer over time. On the other hand, if the weight average molecular weight of the photocurable resin (A) is too large, the compatibility with the thermoplastic resin (B) may decrease, making the reaction difficult to proceed. The weight average molecular weight of the photocurable resin (A) can be measured using the same method as the measurement method of the weight average molecular weight of the above-mentioned thermoplastic resin (B).

[0103] <Photoinitiator (C)> The adhesive layer in the present invention contains one or more photoinitiators (C), so that the reactivity after irradiation with active energy rays is promoted, and the bonding property after curing can be enhanced. In addition, since the above adhesive layer contains a photoinitiator (C) that is activated by light and the reaction proceeds, the reaction continues as it is even after the irradiation with active energy rays is stopped. Therefore, the reaction proceeds even in a dark place or at a low temperature, and a good curing reaction can be obtained. As a result, high bonding properties can be obtained without damaging the members to be joined, deforming the members due to strain between the members, or causing cracks between the adhesive sheet and the members.

[0104] The above photoinitiator (C) is not particularly limited as long as it is activated by light. Examples of the above photoinitiator (C) include photo radical polymerization initiators, photo cationic polymerization initiators, and photo anionic polymerization initiators. Among them, at least one of the photo cationic polymerization initiator and the photo anionic polymerization initiator is preferable, and the photo cationic polymerization initiator is more preferable because the polymerization by the dark reaction can be suitably adjusted.

[0105] The above photo cationic polymerization initiator is not particularly limited as long as it can induce a ring-opening reaction of a cationically polymerizable functional group by light having the wavelength to be used. Among them, compounds that induce a ring-opening reaction of a cationically polymerizable functional group by light having a wavelength of 300 nm to 370 nm and are inactive in the wavelength region exceeding 370 nm are preferably used. Examples of such photo cationic polymerization initiators include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts.

[0106] Specific examples of onium salts include, for example, Optomer SP-150, Optomer SP-170, Optomer SP-171 (all manufactured by ADEKA), UVE-1014 (manufactured by General Electronics), OMNICAT250, OMNICAT270 (all manufactured by IGM Resin), IRGACURE290 (manufactured by BASF), Sun-Aid SI-60L, Sun-Aid SI-80L, Sun-Aid SI-100L (all manufactured by Sanshin Chemical Industry Co., Ltd.), CPI-100P, CPI-101A, CPI-200K (all manufactured by San-Apro), etc.

[0107] The photo cationic polymerization initiator may be used alone or in combination of two or more. Further, a plurality of photo cationic polymerization initiators having different effective active wavelengths may be used for two-stage curing.

[0108] The above photo cationic polymerization initiator may be used in combination with a sensitizer such as an anthracene-based or thioxanthone-based compound as necessary.

[0109] The above photo cationic polymerization initiator is preferably contained in the range of 0.001% by mass to 30% by mass, more preferably in the range of 0.01% by mass to 20% by mass, and still more preferably in the range of 0.1% by mass to 10% by mass in the total solid content of the adhesive layer, in other words, the adhesive composition constituting the adhesive layer. If the blending ratio of the above photo cationic polymerization initiator is too small, the curing necessary for the expression of high bondability becomes insufficient. If it is too large, although the curability is improved, the progress of the curing reaction after light irradiation becomes fast, and it becomes difficult to firmly bond the members because it cannot sufficiently follow and adhere to the adherend surface.

[0110] <Other component (D)> In addition to the above-described photocurable resin (A), thermoplastic resin (B), and photopolymerization initiator (C), the adhesive layer can contain other components (D) as necessary.

[0111] The adhesive layer in the present invention may contain a tacky resin as the other component (D). This is because the adhesive sheet of the present invention can exhibit good adhesion at normal temperature and can further improve the follow-up adhesion to the adherend surface.

[0112] The above tacky resin preferably has a weight average molecular weight in the range of 2,000 to 2,000,000, more preferably in the range of 5,000 to 1,000,000, and even more preferably in the range of 5,000 to 800,000. The weight average molecular weight of the tacky resin can be measured by the same measurement method as the weight average molecular weight of the above-described thermoplastic resin (B).

[0113] Examples of the above tacky resin include polyester, polyurethane, poly(meth)acrylate, polyvinyl acetal, etc. These tacky resins may be homopolymers or copolymers. Further, these tacky resins may be used alone or in combination of two or more.

[0114] The above tacky resin preferably has a glass transition temperature in the range of -30°C to 20°C, and more preferably in the range of -25°C to 10°C. By including a tacky resin having a glass transition temperature within the above range in the adhesive layer, the adhesive sheet of the present invention can exhibit good tackiness and a high elastic modulus at normal temperature, and can exhibit good adhesion and high bonding strength to the adherend.

[0115] The glass transition temperature can be calculated, for example, using a dynamic viscoelasticity tester (manufactured by Rheometric Scientific Co., Ltd., product name: ARES 2KSTD). A test piece of the pressure-sensitive adhesive resin is sandwiched between parallel disks, which are the measuring part of the tester, and the storage modulus (G') and loss modulus (G'') at a frequency of 1.0 Hz are measured. The glass transition temperature can be calculated as the temperature at which the loss tangent (tanδ), which can be calculated as the value obtained by dividing the loss modulus (G'') by the storage modulus (G'), reaches its maximum value.

[0116] The above-mentioned pressure-sensitive adhesive resin may have a functional group capable of reacting with a cross-linking agent or the functional groups contained in the above-mentioned photocurable resin (A) or thermoplastic resin (B). This is because the pressure-sensitive adhesive resin can be cross-linked. Examples of the functional group include a hydroxyl group, a carboxyl group, an epoxy group, an amino group, etc., and it is preferably selected as appropriate within a range that does not inhibit the polymerization reaction of the photocurable resin (A) and thermoplastic resin (B).

[0117] The above-mentioned pressure-sensitive adhesive resin is preferably contained in the range of 0.1 part by mass to 100 parts by mass, more preferably in the range of 1 part by mass to 50 parts by mass, and still more preferably in the range of 5 parts by mass to 30 parts by mass, based on the total amount (100 parts by mass) of the adhesive composition forming the adhesive layer, i.e., the adhesive layer. By setting the blending ratio of the above-mentioned pressure-sensitive adhesive resin within the above range, an adhesive sheet excellent in adhesion at room temperature can be obtained without a decrease in the bondability after curing of the adhesive layer.

[0118] The adhesive layer in the present invention can contain an inorganic filler, an organic filler, a silane coupling agent, a phosphate-based additive, an acrylate-based additive, etc. as other components (D). When the material of the adherend surface contains glass, the adhesive layer can contain a silane coupling agent rich in reactivity with glass to further enhance the adhesiveness to the adherend. Further, the adhesive layer may contain a photocurable silane coupling agent capable of reacting with the photocurable resin (A), thermoplastic resin (B), etc.

[0119] In addition, the adhesive layer in the present invention can contain, as other components (D), for example, softeners, stabilizers, adhesion promoters, leveling agents, defoaming agents, plasticizers, tackifying resins, fibers, antioxidants, hydrolysis inhibitors, thickeners, colorants such as pigments, fillers, tackifying resins, and the like.

[0120] <Others> The adhesive layer in the present invention contains one or more resins (AA) having an epoxy group or an oxetanyl group and a weight average molecular weight in the range of 100 to 5000, and one or more resins (BB) selected from the group consisting of polyester resins, polyurethane resins, acrylic resins, polyvinyl acetal resins, and epoxy resins (thermoplastic epoxy resins) having a polymerizable functional group other than a polymerizable unsaturated double bond and a weight average molecular weight in the range of 5500 to 2000000, and a photopolymerization initiator (C). It is preferable that the content of the resin (BB) is in the range of 15% by mass to 50% by mass. By adopting the above-described composition containing two or more types of resins in combination of a resin with a low weight average molecular weight and a resin with a high weight average molecular weight, the effects of the present invention can be achieved. Here, the resin (AA) and the resin (BB) correspond to the above-described photocurable resin (A) and thermoplastic resin (B), respectively.

[0121] <Physical properties of the adhesive layer> The adhesive layer in the present invention preferably has a thickness of 10 μm or more and 3000 μm or less, more preferably 20 μm or more and 2500 μm or less, still more preferably 30 μm or more and 2000 μm or less, and most preferably 50 μm or more and 650 μm or less. By setting the thickness of the adhesive layer within the above range, it has excellent handleability before curing and can exhibit high follow-up adhesion to the adherend surface. If the thickness of the adhesive layer is smaller than the above range, sufficient adhesive strength may not be obtained due to its thinness. On the other hand, if the thickness of the adhesive layer is larger than the above range, it may be difficult to process it into a sheet shape.

[0122] The adhesive layer in the present invention preferably has a melting point of 25°C or higher, more preferably 30°C or higher, still more preferably 35°C or higher, and most preferably 40°C or higher. Also, the above melting point is preferably 120°C or lower, more preferably 90°C or lower, still more preferably 85°C or lower, and most preferably 60°C or lower. More specifically, the melting point of the adhesive layer can preferably be in the range of 30°C to 120°C, 30°C to 90°C, or 40°C to 85°C. By setting the melting point of the adhesive layer within the above range, the adhesive sheet of the present invention has excellent handleability before curing and better follow-up adhesion to the adherend surface. Incidentally, the melting point of the adhesive layer is the same as the melting point of the adhesive composition constituting the adhesive layer, in other words.

[0123] The melting point of the adhesive layer is the temperature indicating the maximum exothermic peak (top of the exothermic peak) observed when the temperature is raised from 20°C to 150°C at a heating rate of 10°C / min, held for 1 minute, then once cooled to -10°C at a cooling rate of 10°C / min, held for 10 minutes, and then measured again at a heating rate of 10°C / min using differential scanning calorimetry (DSC method).

[0124] In the present invention, the absolute value of the difference between the loss tangent tanδ1 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of -20°C and the loss tangent tanδ2 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of 70°C is preferably 1 or less, more preferably 0.1 or more and 1 or less, still more preferably 0.2 or more and 1 or less, even more preferably 0.25 or more and 0.95 or less, and particularly preferably 0.25 or more and 0.9 or less. By having the absolute value of the difference between the loss tangent tanδ1 and the loss tangent tanδ2 of the cured adhesive layer within the above range, an adhesive layer that is difficult to stretch at high temperatures and difficult to shrink at low temperatures, in other words, an adhesive layer that is less likely to deform during heat cycling, can be obtained.

[0125] The loss tangent tanδ1 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of -20°C is preferably 0.01 or more and 0.1 or less, more preferably 0.02 or more and 0.1 or less, still more preferably 0.02 or more and 0.09 or less, and particularly preferably 0.02 or more and 0.08 or less. This is because when the loss tangent tanδ1 of the cured adhesive layer is within the above range, deformation of the adhesive layer is less likely to occur at low temperatures.

[0126] Further, the loss tangent tanδ2 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of 70°C is preferably 0.2 or more and 0.9 or less, more preferably 0.25 or more and 0.9 or less, still more preferably 0.3 or more and 0.85 or less, and particularly preferably 0.35 or more and 0.80 or less. This is because when the loss tangent tanδ2 of the cured adhesive layer is within the above range, deformation of the adhesive is less likely to occur at low temperatures.

[0127] For the loss tangent tanδ1 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of -20°C and the loss tangent tanδ2 measured at a frequency of 1.0 Hz and a temperature of 70°C, test pieces are prepared by cutting the cured adhesive layer into a circular shape with a thickness of 1 mm and a diameter of 8 mm. Using a dynamic viscoelasticity tester (manufactured by Rheometric Scientific, trade name: ARES 2KSTD), the test pieces are sandwiched between parallel disks, which are the measurement part of the tester, and the storage modulus (G') and loss modulus (G") are measured at a predetermined frequency and temperature. The loss tangent (tanδ) is the value obtained by dividing the above loss modulus (G") by the above storage modulus (G') (G" / G').

[0128] In the present invention, the absolute value of the difference between the storage modulus E'1 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of -20°C and the storage modulus E'2 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of 70°C is preferably 1×10 9 Pa or less, more preferably 1×10 5 Pa or more and 1×10 9 Pa or less, and 1×10 6 Pa or more and 1×109 less than Pa and 5×10 6 Pa or more and 1×10 9 less than Pa and 1×10 8 Pa or more and 1×10 9 less than Pa and 5×10 8 Pa or more and 1×10 9 less than Pa. This is because by having the absolute value of the difference between the storage elastic modulus E’1 and the storage elastic modulus E’2 of the adhesive layer after curing within the above range, the deformation of the adhesive layer during heat cycling can be suppressed.

[0129] In the present invention, the storage elastic modulus E’1 of the above adhesive layer after curing, measured at a frequency of 1.0 Hz and a temperature of -20°C, is 1×10 7 Pa or more and 1×10 10 less than Pa, preferably 5×10 7 Pa or more and 1×10 10 less than, preferably 1×10 8 Pa or more and 1×10 10 less than Pa, preferably 1×10 8 Pa or more and 5×10 9 less than Pa, preferably 5×10 8 Pa or more and 1×10 9 less than Pa, preferably. By having the storage elastic modulus E’1 of the adhesive layer after curing within the above range, it is easier to set the absolute value range of the difference between the above-mentioned storage elastic modulus E’1 and the storage elastic modulus E’2 of the above adhesive layer after curing, measured at a frequency of 1.0 Hz and a temperature of 70°C.

[0130] Also, the storage elastic modulus E’2 of the above adhesive layer after curing, measured at a frequency of 1.0 Hz and a temperature of 70°C, is 1.0×10 5 Pa or more and 1×10 9 less than Pa, preferably 1.0×10 5 Pa or more and 1×10 8 less than Pa, preferably 1.0×10 6 Pa or more and 1×10 8 less than Pa, preferably 5.0×10 6 Pa or more and 1×10 8It is preferably below Pa. When the storage elastic modulus E’2 of the adhesive layer after curing is within the above range, it is easy to define the absolute value range of the difference between the above-mentioned storage elastic modulus E’1 and the storage elastic modulus E’2 of the above adhesive layer after curing measured at a frequency of 1.0 Hz and a temperature of 70°C.

[0131] The storage elastic modulus E’1 of the adhesive layer after curing, measured at a frequency of 1.0 Hz and a temperature of -20°C, and the storage elastic modulus E’2, measured at a frequency of 1.0 Hz and a temperature of 70°C, are values measured at a predetermined frequency and temperature using a dynamic viscoelasticity measuring device (manufactured by Rheometric Scientific, trade name: RSA-II) with test pieces formed by punching out a cured adhesive layer with a thickness of 100 μm into the shape of test piece type 5 of JIS K 7127 using a dumbbell cutter.

[0132] The loss tangents tanδ1 and tanδ2 of the adhesive layer, as well as the storage elastic moduli E’1 and E’2, can be adjusted by appropriately selecting the composition, average molecular weight, etc. of the adhesive composition constituting the adhesive layer.

[0133] In the adhesive sheet of the present invention, the gel fraction of the adhesive layer after curing is preferably 40% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, and particularly preferably 70% by mass or more and 100% by mass or less. By setting the gel fraction within the above range, it is possible to firmly bond the members even after curing and to impart heat resistance.

[0134] The gel fraction is a value calculated based on the following formula from the mass of the adhesive layer remaining in the above solvent after immersing the adhesive layer of the cured adhesive sheet of the present invention in toluene adjusted to 23°C for 24 hours and drying, and the mass of the adhesive layer before toluene immersion. Gel fraction (% by mass) = {(mass of the adhesive layer of the adhesive sheet remaining undissolved in toluene) / (mass of the adhesive layer of the adhesive sheet before toluene immersion)} × 100

[0135] (2) Aspect of the adhesive sheet The adhesive sheet of the present invention may be in an embodiment having an adhesive layer containing the composition described above, and may have any configuration as necessary.

[0136] One embodiment (Embodiment (I)) of the adhesive sheet of the present invention includes an embodiment composed only of an adhesive layer, that is, a substrate-free embodiment. The adhesive sheet of Embodiment (I) contains at least the photocurable resin (A), the thermoplastic resin (B), and the photopolymerization initiator (C) described above, and may be composed of a single adhesive layer formed of an adhesive composition in which the content of the thermoplastic resin (B) is within a predetermined range. Further, the adhesive sheet of Embodiment (I) has only the adhesive layer of a multilayer body in which two or more layers are laminated, and at least the outermost layers on both sides of the adhesive layer of the multilayer body contain at least the photocurable resin (A), the thermoplastic resin (B), and the photopolymerization initiator (C) and the content of the thermoplastic resin (B) is within a predetermined range. It may be composed of an adhesive composition, and among them, it is preferable that all of the plurality of layers constituting the adhesive layer of the multilayer body contain at least the photocurable resin (A), the thermoplastic resin (B), and the photopolymerization initiator (C) and the content of the thermoplastic resin (B) is within a predetermined range.

[0137] In the adhesive sheet of Embodiment (I), release liners may be disposed on one or both of the pair of opposing main surfaces of the adhesive layer. The adhesive sheet of Embodiment (I) is used by peeling off the release liner when bonding to a member. Therefore, in a laminate in which a pair of members are joined via the adhesive sheet of Embodiment (I), the release liner is not included in the configuration of the adhesive sheet.

[0138] Further, as another aspect (Aspect (II)) of the adhesive sheet of the present invention, it has a base material, a first adhesive layer formed on the first main surface of the base material, and a second main surface of the base material facing the first main surface. And a second adhesive layer formed on the surface, wherein the first adhesive layer and the second adhesive layer each contain at least the above-described photocurable resin (A), thermoplastic resin (B), and photopolymerization initiator (C), and the thermoplastic resin (B) An aspect is exemplified in which the content is in a predetermined range and is composed of an adhesive composition. The adhesive sheet of Aspect (II) can increase the strength as a sheet by having a base material between the two adhesive layers. In Aspect (II), only one of the first adhesive layer and the second adhesive layer contains at least the above-described photocurable resin (A), thermoplastic resin (B), and photopolymerization initiator (C), and the content of the thermoplastic resin (B) is It may be composed of an adhesive composition within a predetermined range.

[0139] In the adhesive sheet of Aspect (II), the base material is not particularly limited. For example, a plastic film made of a polyester resin or a polyolefin resin, a plastic foam made of a polyolefin resin, a polyurethane resin, a polychloroprene resin, an acrylic resin, or the like can be used. The base material preferably has light transmissivity. By irradiating light from one adhesive layer side, the other adhesive layer can also be activated through the base material to cause a polymerization reaction.

[0140] In the adhesive sheet of Aspect (II), a release liner may be disposed on at least one of the surface opposite to the surface of the first adhesive layer in contact with the base material and the surface opposite to the surface of the second adhesive layer in contact with the base material, and release liners may be disposed on both surfaces. The adhesive sheet of Aspect (II) is used by peeling off the release liner when bonding to a member. Therefore, in a laminate in which a pair of members are joined via the adhesive sheet of Aspect (II), it is assumed that the release liner is not included in the configuration of the adhesive sheet.

[0141] As the release liner, for example, paper such as kraft paper, glassine paper, or high-quality paper; resin films such as polyethylene, polypropylene (OPP, CPP), or polyethylene terephthalate; laminated paper obtained by laminating the above-mentioned paper and resin film; or those obtained by subjecting one or both sides of the above-mentioned paper treated with a blocking agent such as clay or polyvinyl alcohol to a release treatment with a silicone-based resin or the like can be used.

[0142] When the adhesive sheet of the present invention is irradiated with light, polymerization starts in the adhesive layer and curing proceeds. The adhesive layer in the present invention is activated by light, so that curing does not proceed regardless of the storage temperature in the state where no light is irradiated, and the storage stability before curing is good. Further, in the adhesive layer of the present invention, since the reactive sites are activated by light irradiation without heating, the curing reaction can proceed even at low temperatures.

[0143] In addition to light, the adhesive sheet of the present invention can promote the curing reaction by further applying external stimuli such as heat and moisture (humidity). Among them, it is preferable to use light and heat in combination as the curing means of the adhesive sheet of the present invention. By irradiating the adhesive sheet with light first, the adhesive layer is activated to start polymerization, and after the adhesive sheet is bonded to a member (adherend), heating can promote the curing reaction. Thereby, curing by high-temperature heating becomes unnecessary, and the curing reaction can proceed even at low temperatures. When heat is used in combination, since the progress of the reaction has already started by light irradiation, heat is used only for the purpose of promoting the curing reaction, and there is no need to heat at a high temperature, and a good curing reaction can be obtained even with a reaction at low temperature and for a short time.

[0144] (3) Method for manufacturing the adhesive sheet The adhesive sheet of the present invention can be produced using an adhesive solution obtained by mixing an adhesive composition containing at least the above-described photocurable resin (A), thermoplastic resin (B), and photopolymerization initiator (C) and having the content of the thermoplastic resin (B) within a predetermined range in a solvent. Specifically, the adhesive sheet of the present invention can be produced, for example, by applying the above-described adhesive solution to the surface of a release sheet, drying to form an adhesive layer, and removing the release sheet. By forming the adhesive layer using the adhesive solution in which the adhesive composition is mixed with a solvent, the dispersibility of the additive (D) in the adhesive layer is improved as compared with the case of directly applying the adhesive.

[0145] Further, the adhesive sheet of the present invention can be produced, for example, by applying the above-described adhesive solution to both surfaces of a substrate, drying to form an adhesive layer.

[0146] Further, the adhesive sheet of the present invention can be produced, for example, by applying the above-described adhesive solution to the surface of a release sheet, drying to form an adhesive layer, and attaching a substrate to the surface of the adhesive layer.

[0147] When producing an adhesive sheet in which two or more adhesive layers having the same or different compositions are laminated, for example, an adhesive solution containing the adhesive composition 1 is applied to both surfaces of a substrate, dried to form the first adhesive layer 1, and an adhesive solution containing the adhesive composition 2 is applied to the surface of the first adhesive layer 1 and dried to form the second adhesive layer 2. In this case, at least the adhesive composition 2 should contain at least the above-described photocurable resin (A), thermoplastic resin (B), and photopolymerization initiator (C) and have the content of the thermoplastic resin (B) within a predetermined range. It is preferable that both the adhesive compositions 1 and 2 contain at least the above-described photocurable resin (A), thermoplastic resin (B), and photopolymerization initiator (C) and have the content of the thermoplastic resin (B) within a predetermined range.

[0148] In addition, the adhesive sheet of the present invention can be produced, for example, by applying an adhesive solution containing the adhesive composition 1 to the surface of a release sheet and drying it to form the adhesive layer 1, and then applying an adhesive solution containing another adhesive composition 2 to the surface of the adhesive layer 1 and drying it to form the adhesive layer 2. In this case, at least one of the adhesive compositions 1 and 2 contains at least the above-described photocurable resin (A), thermoplastic resin (B), and photopolymerization initiator (C), and the content of the thermoplastic resin (B) is within a predetermined range. Among them, it is preferable that both the adhesive compositions 1 and 2 contain at least the above-described photocurable resin (A), thermoplastic resin (B), and photopolymerization initiator (C), and the content of the thermoplastic resin (B) is within a predetermined range.

[0149] The adhesive solution used in the method for producing the adhesive sheet of the present invention can be prepared by mixing an adhesive composition containing at least the above-described photocurable resin (A), thermoplastic resin (B) having a predetermined content, and photopolymerization initiator (C) with a solvent. Examples of the solvent used in the adhesive solution include ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone; and aromatic hydrocarbon solvents such as toluene and xylene. For mixing the adhesive composition and the solvent, a dissolver, a butterfly mixer, a BDM two-shaft mixer, a planetary mixer, etc. can be used.

[0150] In the method for producing the adhesive sheet of the present invention, after applying the adhesive solution, a drying step for removing the solvent is included. The drying step is preferably carried out at a temperature of preferably 40°C to 120°C, more preferably about 50°C to 90°C. This is because it can suppress the progress of the curing reaction of the adhesive sheet before light irradiation and can also suppress the foaming of the sheet surface due to the rapid volatilization of the solvent and the like.

[0151] (4) Use The adhesive sheet of the present invention can be used without being restricted by the light transmittance of the member. Therefore, the members joined using the adhesive sheet of the present invention may or may not have light transmittance. Among them, the adhesive sheet of the present invention can be suitably used for joining members with low light transmittance or light-impermeable members. As described above, the adhesive sheet of the present invention has a slow curing reaction rate after light irradiation and can have flexibility for a desired time after light irradiation. For this reason, when joining members, by irradiating the adhesive sheet with light in advance, the curing reaction proceeds without irradiating the adhesive sheet with light through the members, and the members can be firmly joined. In this specification, it is preferable that the member (adherend) has a light transmittance of 90% or less in the wavelength range of 200 nm to 780 nm. Among them, a transmittance of 80% or less, 70% or less, 60% or less, and 50% or less is preferable. In addition, a light-impermeable member refers to a member having a light transmittance of 0% in the above wavelength range. Note that the light transmittance of the adherend (member) is a value measured with an ultraviolet-visible spectrophotometer such as V-570 manufactured by JASCO Corporation.

[0152] Further, the adhesive sheet of the present invention can be used without being restricted by the heat resistance of the member. Therefore, the members joined using the adhesive sheet of the present invention may or may not have heat resistance. As described above, since the curing reaction of the adhesive sheet of the present invention proceeds by light irradiation and it has flexibility for a desired time after light irradiation, the curing reaction proceeds without heating or pressurizing at a high temperature. Note that in order to accelerate the curing reaction, light irradiation and heat treatment may be used in combination as curing means, and it is preferable that the above member has heat resistance capable of withstanding the heating temperature of the heat treatment performed to accelerate the curing reaction after light irradiation.

[0153] The adhesive sheet of the present invention can be suitably used for joining the same or different members. Among them, the adhesive sheet of the present invention can be suitably used for joining constituent members of portable electronic devices, image display devices, etc., and is suitably used for joining members such as image display panels, circuit boards, rear covers, bezels, frames, and chassis.

[0154] 2. Laminate The laminate of the present invention has the adhesive sheet described in the section of "1. Adhesive Sheet" above, a first member bonded to the first main surface of the adhesive sheet, and a second member bonded to the second main surface of the adhesive sheet.

[0155] In the laminate of the present invention, the adhesive layer of the adhesive sheet is cured. That is, in the laminate of the present invention, the first member and the second member are joined by the cured adhesive layer of the adhesive sheet. In other words, the first member and the second member are joined by the cured product layer of the adhesive composition described in the section of "1. Adhesive Sheet" above.

[0156] According to the laminate of the present invention, since the first and second members are joined via the adhesive sheet described in the section of "1. Adhesive Sheet" above, the members are difficult to peel off and can exhibit a high interlayer peeling force. Also, since the cured adhesive layer has followability to the adherend and is less likely to expand and contract with temperature changes, even in an environment with large temperature changes, problems such as breakage or defects of the laminate due to the expansion and contraction of the adhesive sheet are less likely to occur, and it can have high cold and heat cycle resistance characteristics.

[0157] In the laminate of the present invention, it is sufficient that the first member is bonded to the first main surface of the adhesive sheet described in the section of "1. Adhesive Sheet" above, and the second member is bonded to the second main surface of the adhesive sheet facing the first main surface of the adhesive sheet, and the number of the first and second members is not limited. That is, in the laminate of the present invention, one first member may be bonded to the first main surface of the adhesive sheet, and one second member may be joined to the second main surface of the adhesive sheet. One first member may be bonded to the first main surface of the adhesive sheet, and a plurality of second members may be provided on the second main surface of the adhesive sheet. A plurality of first members may be bonded to the first main surface of the adhesive sheet, and a plurality of second members may be provided on the second main surface of the adhesive sheet.

[0158] The members in the laminate of the present invention may or may not have light transmissibility. The light transmittance of the member with low light transmissibility is as described in the section of "1. Adhesive Sheet" above. Further, the above member may or may not have heat resistance, but it preferably has heat resistance that can withstand the heating temperature of the heat treatment performed to promote the curing reaction after light irradiation.

[0159] When the laminate of the present invention is used in an image display device, examples of the member include an image display panel, a circuit board, a rear cover, a bezel, a frame, a chassis, etc.

[0160] The laminate of the present invention can be used in an image display device. Examples of the above image display device include mobile terminals (PDAs) such as personal computers, mobile phones, smartphones, tablet PCs, game machines, televisions (TVs), car navigation systems, touch panels, pen tablets, etc., and components of flat panel image display devices using image display panels equipped with LCD, PDP, or EL, organic EL, micro LED, quantum dot (QD), etc.

[0161] 3. Method for manufacturing laminate The method for manufacturing the laminate of the present invention is a method for manufacturing a laminate using the adhesive sheet described in the section of "1. Adhesive Sheet" above, and includes a step [1] of bonding a first member to the first main surface of the adhesive sheet, a step [2] of bonding a second member to the second main surface of the adhesive sheet, and a step [3] of curing the adhesive layer of the adhesive sheet. Further, before the step [1], or between the step [1] and the step [2], there is a step of irradiating the first main surface or the second main surface of the adhesive sheet with active energy rays (hereinafter, may be referred to as step [0]).

[0162] In the case where the adhesive sheet in the present invention is the adhesive sheet of the above-described aspect (I), the first and second main surfaces of the adhesive sheet refer to the two outermost surfaces facing each other of the single-layer or multi-layer adhesive layer. Further, in the case where the adhesive sheet in the present invention is the adhesive sheet of the above-described aspect (II), the first and second main surfaces of the adhesive sheet refer to the surface on the first adhesive layer side and the surface on the second adhesive layer side of the adhesive sheet of aspect (II), respectively.

[0163] In the above step [1], it is preferable to press-bond and bond the first member to the first main surface of the adhesive sheet. Further, in the above step [2], it is preferable to press-bond and bond the second member to the second main surface of the adhesive sheet. By press-bonding and bonding the member to the adhesive sheet, the adhesive sheet can easily follow the adherend surface of the member, and the adhesion between the adhesive sheet and the member can be enhanced. Therefore, the bonding strength between the first member and the second member via the cured adhesive layer is further increased.

[0164] In the above steps [1] and [2], the pressure when press-bonding the member to the adhesive sheet can be in the range of 0.1 to 3000 KPa, preferably in the range of 0.5 to 1000 kPa, and more preferably in the range of 1.0 to 500 kPa. By press-bonding within the above range, the member can be bonded to the adhesive sheet without being damaged, and the adhesion necessary to obtain a high bonding strength can be obtained.

[0165] In the above steps [1] and [2], the member may be pressure-bonded to the adhesive sheet while heating. By performing pressure-bonding while heating, when joining the members via the above adhesive sheet, they can adhere more firmly and a high bonding strength can be obtained. The heating temperature can be set within a range that does not cause damage to the member, deformation of the member due to strain occurring between the members, or cracks occurring between the adhesive sheet and the member. Preferably, it can be 150°C or lower, 120°C or lower, 100°C or lower, 80°C or lower, 70°C or lower. By setting the upper limit of the heating temperature, damage to the member can be suppressed, and deformation of the member due to strain occurring between the members and the occurrence of cracks between the adhesive sheet and the member can be suppressed. Also, the heating temperature can preferably be 5°C or higher, 10°C or higher, 20°C or higher, 30°C or higher, 40°C or higher. This is because by setting the lower limit of the heating temperature, the followability of the adhesive sheet to the adherend surface is improved. The pressure-bonding time is not particularly limited as long as it is a time that allows sufficient follow-up and adhesion to the adherend surface of the member.

[0166] The above step [3] may involve a heat treatment. In the manufacturing method of the present invention, since the curing reaction of the adhesive sheet starts by irradiating active energy rays, curing proceeds even at normal temperature. However, by performing the above step [3] while heating, when joining the members via the above adhesive sheet, the curing reaction is promoted and a high bonding strength can be obtained in a shorter time.

[0167] When performing a heat treatment in the above step [3], the heating conditions can be set within a range that does not cause damage to the members to be laminated, deformation of the members due to strain occurring between the members, or cracks occurring between the adhesive sheet and the members. The heating temperature is preferably 150°C or lower, more preferably 120°C or lower, still more preferably 100°C or lower, and most preferably 80°C or lower in order to suppress damage to the members to be laminated and deformation and flow of the adhesive layer.

[0168] In the above step [3], it is preferable to proceed with the curing reaction so that the cured adhesive layer exhibits the gel fraction described in the section of "1. Adhesive Sheet" above.

[0169] The step of irradiating the active energy rays onto the first major surface or the second major surface of the sheet (Step [0]) can be carried out before Step [1]. In this case, Step [1] and Step [2] are preferably carried out within 24 hours, more preferably within 12 hours, still more preferably within 3 hours, and most preferably within 1 hour after Step [0] is carried out, because when the adhesive sheet is attached to the member, it adheres more firmly and a high bonding strength can be obtained.

[0170] Also, Step [0] may be carried out between Step [1] and Step [2]. In this case, Step [2] is preferably carried out within 24 hours, more preferably within 12 hours, still more preferably within 3 hours, and most preferably within 1 hour after Step [0] is carried out, because when the adhesive sheet is attached to the member, it adheres more firmly and a high bonding strength can be obtained.

[0171] As the active energy rays, ultraviolet rays, visible light, etc. are preferably used, and among them, it is preferable to use ultraviolet rays. The ultraviolet rays may be irradiated in an inert gas atmosphere such as nitrogen gas or in an air atmosphere in order to efficiently carry out the curing reaction by ultraviolet rays. Further, heat may be used in combination as an energy source as necessary, and heating may be carried out after light irradiation.

[0172] Also, the light to be irradiated preferably has a wavelength region capable of activating the photopolymerization initiator (C), and among them, it is preferable to use active energy rays having a wavelength of 300 nm or more and 420 nm or less.

[0173] Examples of the light source when irradiating with active energy rays include, for example, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, electrodeless lamps (fusion lamps), chemical lamps, black light lamps, xenon lamps, mercury-xenon lamps, short arc lamps, helium-cadmium lasers, argon lasers, sunlight, LEDs, germicidal lamps, carbon arcs, scanning type, curtain type electron beam accelerators, etc. Also, a xenon-flash lamp that can irradiate light in a flash is preferable because it can minimize the influence of heat.

[0174] The irradiation intensity of the above active energy rays is preferably 0.1 to 1000 mW / cm 2 is more preferably 0.5 to 800 mW, and even more preferably 0.1 to 400 mW / cm 2 is even more preferable. Also, the irradiation time of the above active energy rays is preferably 1 to 60 seconds, more preferably 5 to 50 seconds, and even more preferably 10 to 40 seconds. By setting the irradiation intensity and time within the above ranges, the heat generated when irradiating with active energy rays can be reduced, so that the curing rate after irradiating with active energy rays can be suitably adjusted.

[0175] The irradiation of the above active energy rays may be performed once or divided into a plurality of times.

[0176] Specific examples of the laminate that can be manufactured according to the present invention include the specific examples described in the section of "2. Laminate" above.

[0177] The present disclosure is not limited to the above embodiments. The above embodiments are examples, and those having substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibiting the same operational effects are included in the technical scope of the present disclosure regardless of what they are.

Examples

[0178] The present invention will be described more specifically below with reference to Examples and Comparative Examples.

[0179] 1. Synthesis of thermoplastic resin (B) <Preparation of polyurethane (B-1)> In a reaction vessel, 60 parts by mass of an aliphatic polycarbonate polyol with a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, and 60 parts by mass of a polyester polyol with a number average molecular weight of 4500 obtained by reacting 1,6-hexanediol and adipic acid were mixed, and heated to 100 °C under reduced pressure conditions to dehydrate until the moisture content reached 0.05% by mass to obtain a mixture.

[0180] Next, the above mixture cooled to 70 °C was mixed with 8.0 parts by mass of dicyclohexylmethane-4,4'-diisocyanate, then the temperature was raised to 100 °C and reacted for 3 hours until the hydroxyl group content became constant to obtain polyurethane (B-1). The above polyurethane (B-1) has a hydroxyl group as a polymerizable functional group.

[0181] <Preparation of polyurethane (B-2)> In a reaction vessel, 14 parts by mass of an aromatic polyester polyol with a number average molecular weight of 2000 obtained by reacting an ethylene oxide 6-mol adduct of bisphenol A, isophthalic acid and sebacic acid, 37 parts by mass of an aromatic polyester polyol with a number average molecular weight of 1300 obtained by reacting an ethylene oxide 2-mol adduct of bisphenol A, phthalic acid and adipic acid, 32 parts by mass of an aliphatic polyester polyol with a number average molecular weight of 3500 obtained by reacting 1,6-hexanediol and dodecanedioic acid, 7 parts by mass of polypropylene glycol with a number average molecular weight of 1000, and 2 parts by mass of an ethylene oxide 2-mol adduct of bisphenol A were mixed, and heated to 100 °C under reduced pressure conditions to dehydrate until the moisture content reached 0.05% by mass to obtain a mixture.

[0182] Next, the above mixture cooled to 70°C was mixed with 8.0 parts by mass of 4,4′-diphenylmethane diisocyanate, and then the temperature was raised to 100°C and reacted for 3 hours until the hydroxyl group content became constant, thereby obtaining polyurethane (B-2). Note that the above polyurethane (B-2) has a hydroxyl group as a polymerizable functional group.

[0183] <Preparation of Polyurethane (B-3)> Into a reaction vessel, 51 parts by mass of an aromatic polyester polyol having a number average molecular weight of 1300 obtained by reacting an ethylene oxide 2-mol adduct of bisphenol A, phthalic acid, and adipic acid, 32 parts by mass of an aliphatic polyester polyol having a number average molecular weight of 3500 obtained by reacting 1,6-hexanediol and dodecanedioic acid, 7 parts by mass of a polypropylene glycol having a number average molecular weight of 1000, and 2 parts by mass of an ethylene oxide 2-mol adduct of bisphenol A were mixed, and the mixture was heated to 100°C under reduced pressure conditions to dehydrate until the water content became 0.05% by mass to obtain a mixture.

[0184] Next, the above mixture cooled to 70°C was mixed with 8.0 parts by mass of 4,4′-diphenylmethane diisocyanate, and then the temperature was raised to 100°C and reacted for 3 hours until the hydroxyl group content became constant, thereby obtaining polyurethane (B-3). Note that the above polyurethane (B-3) has a hydroxyl group as a polymerizable functional group.

[0185] <Preparation of Polyurethane (B-4)> Into a reaction vessel, 50.3 parts by mass of an aromatic polyester polyol having a number average molecular weight of 1300 obtained by reacting an ethylene oxide 2-mol adduct of bisphenol A, phthalic acid, and adipic acid, 32 parts by mass of an aliphatic polyester polyol having a number average molecular weight of 3500 obtained by reacting 1,6-hexanediol and dodecanedioic acid, 32.2 parts by mass of a polypropylene glycol having a number average molecular weight of 1000, and 1.8 parts by mass of an ethylene oxide 2-mol adduct of bisphenol A were mixed, and the mixture was heated to 100°C under reduced pressure conditions to dehydrate until the water content became 0.05% by mass to obtain a mixture.

[0186] Next, the above mixture cooled to 70°C was mixed with 4.3 parts by mass of 4,4'-diphenylmethane diisocyanate and 4.3 parts by mass of 2,4'-diphenylmethane diisocyanate, and then the temperature was raised to 100°C and reacted for 5 hours until the hydroxyl group content became constant, thereby obtaining polyurethane (B-4). Note that the above polyurethane (B-4) has a hydroxyl group as a polymerizable functional group.

[0187] <Preparation of Polyurethane (B-5)> In a reaction vessel, 60 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, and 20 parts by mass of a polyester polyol having a number average molecular weight of 1000 obtained by reacting 1,4-butanediol and adipic acid were mixed, and heated to 100°C under reduced pressure conditions to dehydrate until the moisture content became 0.05% by mass to obtain a mixture.

[0188] Next, the above mixture cooled to 70°C was mixed with 20 parts by mass of dicyclohexylmethane-4,4'-diisocyanate, and then the temperature was raised to 100°C and reacted for 3 hours to obtain a urethane prepolymer having an isocyanate group. 100 parts by mass of the above urethane prepolymer heated and melted at 100°C was mixed with 11.4 parts by mass of 2-hydroxyethyl acrylate and 0.01 parts by mass of stannous octylate, and reacted at 100°C until the NCO% became constant, thereby obtaining polyurethane (B-5). Note that polyurethane (B-3) has a polymerizable unsaturated double bond as a polymerizable functional group, and the isocyanate group content (NCO%) was 0% by mass.

[0189] 2. Preparation of Adhesive Sheet (Example 1) 43 parts by mass of the above polyurethane (B-4), 22 parts by mass of an alicyclic epoxy resin ("CEL-2021P" manufactured by Daicel Corporation), 35 parts by mass of a cresol novolac type epoxy resin ("N-685-EXP-S" manufactured by DIC Corporation), and 1.6 parts by mass of a sulfonium salt-based photo cationic polymerization initiator ("CPI-100P" manufactured by San-Apro Limited, solid content concentration 50%) were mixed and stirred, and methyl ethyl ketone was added and adjusted so that the non-volatile content became 75% by mass to obtain an adhesive solution containing an adhesive composition (a-1).

[0190] Next, an adhesive solution containing the above adhesive composition (a-1) was applied to the surface of a release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying became 150 μm, and it was put into a dryer at 85°C for 5 minutes and dried to obtain a coated layer of the adhesive composition (a-1).

[0191] Furthermore, three of the above coated layers were laminated by bonding to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side, and a release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which was subjected to a release treatment with a silicone compound) was bonded to the other side of the above adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0192] (Example 2) 33 parts by mass of the above polyurethane (B-3), 22 parts by mass of an alicyclic epoxy resin ("CEL-2021P" manufactured by Daicel Corporation), 45 parts by mass of a cresol novolac type epoxy resin ("N-685-EXP-S" manufactured by DIC Corporation), 1.6 parts by mass of a sulfonium salt-based photo cationic polymerization initiator ("CPI-100P" manufactured by San-Apro Limited, solid content concentration 50%), and 6 parts by mass of calcium bicarbonate particles ("BF-200" manufactured by Shiraishi Calcium Co., Ltd., average particle diameter 5 μm) were mixed and stirred, and methyl ethyl ketone was added and adjusted so that the non-volatile content became 75% by mass to obtain an adhesive solution containing an adhesive composition (a-2).

[0193] Next, an adhesive solution containing the above adhesive composition (a-2) was applied onto the surface of the release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and then it was put into a dryer at 85°C for 5 minutes for drying to obtain a coating layer of the adhesive composition (a-2).

[0194] Furthermore, three of the above coating layers were laminated together to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side. A release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which was subjected to a release treatment with a silicone compound) was laminated onto the other side of the above adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0195] (Example 3) 43 parts by mass of the above polyurethane (B-4), 22 parts by mass of an alicyclic epoxy resin (“CEL-2021P” manufactured by Daicel Corporation), 35 parts by mass of a cresol novolak type epoxy resin (“N-685-EXP-S” manufactured by DIC Corporation), 2 parts by mass of a sulfonium salt-based photo cationic polymerization initiator (“CPI-100P” manufactured by San-Apro, solid content concentration 50%), and 5 parts by mass of calcium bicarbonate particles (“BF-200” manufactured by Shiraishi Calcium Co., Ltd., average particle size 5 μm) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass to obtain an adhesive solution containing an adhesive composition (a-3).

[0196] Next, an adhesive solution containing the above adhesive composition (a-3) was applied onto the surface of the release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and then it was put into a dryer at 85°C for 5 minutes for drying to obtain a coating layer of the adhesive composition (a-3).

[0197] Furthermore, three coating layers were laminated together to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side, and a release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which was subjected to a release treatment with a silicone compound) was laminated on the other side of the adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner). <> <>

[0198] <> (Example 4)<> 43 parts by mass of the above polyurethane (B-4), 22 parts by mass of an alicyclic epoxy resin ("CEL-2021P" manufactured by Daicel Corporation), 35 parts by mass of a cresol novolak type epoxy resin ("N-685-EXP-S" manufactured by DIC Corporation), 2 parts by mass of a sulfonium salt-based photo cationic polymerization initiator ("CPI-100P" manufactured by San-Apro Limited, solid content concentration 50%), and 10.0 parts by mass of hydrophobic silica particles ("Silophobic 603" manufactured by Fuji Silysia Chemical Ltd., average particle diameter 6.7 μm) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass to obtain an adhesive solution containing an adhesive composition (a-4). <> <>

[0199] <> Next, an adhesive solution containing the above adhesive composition (a-4) was applied to the surface of the release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and it was placed in a dryer at 85°C for 5 minutes and dried to obtain a coating layer of the adhesive composition (a-4). <> <>

[0200] <> Furthermore, three coating layers were laminated together to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side, and a release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which was subjected to a release treatment with a silicone compound) was laminated on the other side of the adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner). <> <>

[0201] <> (Example 5)<> 43 parts by mass of the above polyurethane (B-4), 22 parts by mass of an alicyclic epoxy resin ("CEL-2021P" manufactured by Daicel Corporation), 35 parts by mass of a cresol novolak type epoxy resin ("N-685-EXP-S" manufactured by DIC Corporation), 2 parts by mass of a sulfonium salt-based photo cationic polymerization initiator ("CPI-100P" manufactured by San-Apro Ltd., solid content concentration 50%), and 13.3 parts by mass of calcium bicarbonate particles ("BF-200" manufactured by Shiraishi Calcium Co., Ltd., average particle diameter 5 μm) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass, thereby obtaining an adhesive solution containing an adhesive composition (a-5).

[0202] Next, on the surface of a release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which is subjected to a release treatment with a silicone compound), the adhesive solution containing the above adhesive composition (a-5) was applied using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and it was put into a dryer at 85°C for 5 minutes and dried to obtain a coating layer of the adhesive composition (a-5).

[0203] Furthermore, three of the above coating layers were laminated by bonding to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side, and a release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which is subjected to a release treatment with a silicone compound) was bonded to the other side of the above adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0204] (Example 6) 43 parts by mass of the above polyurethane (B-4), 22 parts by mass of an alicyclic epoxy resin ("CEL-2021P" manufactured by Daicel Corporation), 35 parts by mass of a cresol novolak type epoxy resin ("N-685-EXP-S" manufactured by DIC Corporation), 2 parts by mass of a sulfonium salt-based photo cationic polymerization initiator ("CPI-100P" manufactured by San-Apro Ltd., solid content concentration 50%), and 20.0 parts by mass of hydrophobic silica particles ("Silophobic 603" manufactured by Fuji Silysia Chemical Ltd., average particle diameter 6.7 μm) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass, thereby obtaining an adhesive solution containing an adhesive composition (a-6).

[0205] Next, an adhesive solution containing the above adhesive composition (a-6) was applied to the surface of the release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and then it was put into a dryer at 85°C for 5 minutes to be dried, thereby obtaining a coating layer of the adhesive composition (a-6).

[0206] Furthermore, three of the above coating layers were laminated by bonding to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side, and a release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which was subjected to a release treatment with a silicone compound) was bonded to the other side of the adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0207] (Example 7) 58 parts by mass of the above polyurethane (B-2), 22 parts by mass of an alicyclic epoxy resin ("CEL-2021P" manufactured by Daicel Corporation), 20 parts by mass of a cresol novolak type epoxy resin ("N-685-EXP-S" manufactured by DIC Corporation), 2 parts by mass of a sulfonium salt-based photo cationic polymerization initiator ("CPI-100P" manufactured by San-Apro Limited, solid content concentration 50%), and 60.0 parts by mass of hydrophobic silica particles ("Silophobic 603" manufactured by Fuji Silysia Chemical Ltd., average particle diameter 6.7 μm) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass, thereby obtaining an adhesive solution containing an adhesive composition (a-7).

[0208] Next, an adhesive solution containing the above adhesive composition (a-7) was applied to the surface of the release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and then it was put into a dryer at 85°C for 5 minutes to be dried, thereby obtaining a coating layer of the adhesive composition (a-7).

[0209] Furthermore, three coating layers were laminated together to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side. A release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which was subjected to a release treatment with a silicone compound) was laminated on the other side of the adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0210] (Comparative Example 1) 70 parts by mass of the polyurethane (B-1), 30 parts by mass of an alicyclic epoxy resin (manufactured by Daicel Corporation, "CEL-2021P"), and 2 parts by mass of a sulfonium salt-based photo cationic polymerization initiator (manufactured by San-Apro Co., Ltd., "CPI-100P", solid content concentration 50%) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass to obtain an adhesive solution containing an adhesive composition (b-1).

[0211] Next, an adhesive solution containing the adhesive composition (b-1) was applied to the surface of the release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and it was placed in a dryer at 85°C for 5 minutes and dried to obtain a coating layer of the adhesive composition (b-1).

[0212] Furthermore, three coating layers were laminated together to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side. A release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which was subjected to a release treatment with a silicone compound) was laminated on the other side of the adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0213] (Comparative Example 2) 58 parts by mass of the above polyurethane (B-2), 22 parts by mass of an alicyclic epoxy resin ("CEL-2021P" manufactured by Daicel Corporation), 20 parts by mass of a cresol novolak type epoxy resin ("N-685-EXP-S" manufactured by DIC Corporation), and 4 parts by mass of a sulfonium salt-based photo cationic polymerization initiator ("CPI-100P" manufactured by San-Apro Limited, solid content concentration 50%) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass, thereby obtaining an adhesive solution containing an adhesive composition (b-2).

[0214] Next, on the surface of a release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which has been subjected to a release treatment with a silicone compound), the adhesive solution containing the above adhesive composition (b-2) was applied using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and then it was put into a dryer at 85°C for 5 minutes and dried to obtain a coating layer of the adhesive composition (b-2).

[0215] Furthermore, three of the above coating layers were laminated by bonding to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side, and a release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which has been subjected to a release treatment with a silicone compound) was bonded to the other side of the above adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0216] (Comparative Example 3) 23 parts by mass of the above polyurethane (B-4), 22 parts by mass of an alicyclic epoxy resin ("CEL-2021P" manufactured by Daicel Corporation), 55 parts by mass of a cresol novolak type epoxy resin ("N-685-EXP-S" manufactured by DIC Corporation), 2 parts by mass of a sulfonium salt-based photo cationic polymerization initiator ("CPI-100P" manufactured by San-Apro Limited, solid content concentration 50%), and 95 parts by mass of calcium bicarbonate particles ("BF-200" manufactured by Shiraishi Calcium Co., Ltd., average particle diameter 5 μm) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass, thereby obtaining an adhesive solution containing an adhesive composition (b-3).

[0217] Next, an adhesive solution containing the above adhesive composition (b-3) was applied to the surface of the release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and then it was put into a dryer at 85°C for 5 minutes and dried to obtain a coating layer of the adhesive composition (b-3).

[0218] Furthermore, three of the above coating layers were laminated by bonding to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side, and a release liner B (a polyethylene terephthalate film with a thickness of 38 μm, one side of which was subjected to a release treatment with a silicone compound) was bonded to the other side of the above adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0219] (Comparative Example 3) 100 parts by mass of the above urethane resin (B-5), 43 parts by mass of an alicyclic epoxy resin (“CEL-2021P” manufactured by Daicel Corporation), and 11.4 parts by mass of a sulfonium salt-based photo cationic polymerization initiator (“CPI-100P” manufactured by San-Apro, solid content concentration 50%) were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75% by mass to obtain an adhesive solution containing the adhesive composition (b-5).

[0220] Next, an adhesive solution containing the above adhesive composition (b-5) was applied to the surface of the release liner A (a polyethylene terephthalate film with a thickness of 50 μm, one side of which was subjected to a release treatment with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying would be 150 μm, and then it was put into a dryer at 85°C for 5 minutes and dried to form a coating layer of the adhesive composition (b-5).

[0221] Furthermore, three coating layers were laminated together to form an adhesive layer of a multilayer body with a thickness of 450 μm having a release liner A on one side, and a release liner B (one side of a polyethylene terephthalate film with a thickness of 38 μm was subjected to a release treatment with a silicone compound) was laminated on the other side of the adhesive layer to obtain an adhesive sheet with a total thickness of 450 μm (excluding the thickness of the release liner).

[0222] 3. Evaluation [Measurement method of storage elastic modulus (E’2) at 70°C] The adhesive sheets obtained in the examples and comparative examples were irradiated with ultraviolet rays with an intensity of 300 mW / cm2 for 15 seconds using an air-cooled mercury lamp (manufactured by Eye Graphics Co., Ltd.). At this time, the above ultraviolet irradiation was performed without removing the release liner. After the above ultraviolet irradiation, the adhesive sheet was left to heat at 80°C for 3 hours, left to stand in a 23°C environment for 30 minutes or more, and then cooled to obtain a cured product of the adhesive sheet (cured adhesive layer). Then, the above cured product (cured adhesive layer) was punched into the shape of test piece type 5 of JIS K 7127 using a dumbbell cutter, and the one obtained by removing the release liner was used as a test sample of the cured adhesive layer. The dynamic viscoelasticity of the above test sample was measured using a dynamic viscoelasticity measuring device (manufactured by Rheometric Scientific, trade name: RSA-II), and the storage elastic modulus (E’2) at a frequency of 1.0 Hz and a temperature of 70°C was measured.

[0223] [Measurement method of storage elastic modulus (E’1) at -20°C] Test samples were prepared in the same manner as the measurement method of the storage elastic modulus (E’2) at 70°C, and the storage elastic modulus (E’1) at a frequency of 1.0 Hz and a temperature of -20°C was measured using a dynamic viscoelasticity measuring device (manufactured by Rheometric Scientific, trade name: RSA-II).

[0224] [Measurement method of loss tangent (tanδ2) at 70°C] The adhesive sheets obtained in the examples and comparative examples were irradiated with ultraviolet rays having an intensity of 300 mW / cm2 for 15 seconds using an air-cooled mercury lamp (manufactured by Eye Graphics Co., Ltd.). At this time, the above ultraviolet irradiation was performed without removing the release liner. The adhesive sheet after the above ultraviolet irradiation was left to stand at 80°C for 3 hours, left to stand in a 23°C environment for 30 minutes or more, and then cooled to obtain a cured product (cured adhesive layer) of the above adhesive sheet. Then, the above cured product (cured adhesive layer) was punched into the shape of test piece type 5 of JIS K 7127 using a dumbbell cutter, and the one obtained by removing the release liner was used as a test sample of the cured adhesive layer. The dynamic viscoelasticity of the above test sample was measured using a dynamic viscoelasticity measuring device (manufactured by Rheometric Scientific, product name: RSA-II), and the loss tangent (tanδ2) at a frequency of 1.0 Hz and a temperature of 70°C was measured.

[0225] [Method for measuring loss tangent (tanδ1) at -20°C] Test samples were prepared in the same manner as the method for measuring the loss tangent (tanδ2) at 70°C, and the loss tangent (tanδ1) at a frequency of 1.0 Hz and a temperature of -20°C was measured using a dynamic viscoelasticity measuring device (manufactured by Rheometric Scientific, product name: RSA-II).

[0226] [Peel resistance test during thermal cycling (heat cycle test)] The adhesive sheets obtained in the examples and comparative examples were cut into a size of 50 mm in width × 80 mm in length, one release liner was removed, and they were press-bonded to a CFRP plate (plain weave, epoxy resin type) with a width of 50 mm × a length of 80 mm × a thickness of 1.5 mm at a temperature of 80°C and a pressure of 0.05 MPa for 30 seconds to create a bonded product. After leaving the above bonded product in a temperature environment of 23°C for 60 minutes, it was irradiated with ultraviolet rays having an intensity of 300 mW / cm2 for 15 seconds using an air-cooled mercury lamp (manufactured by Eye Graphics Co., Ltd.). At this time, the above ultraviolet irradiation was performed without removing the release liner.

[0227] After leaving the adherend after the above ultraviolet irradiation in a temperature environment of 23°C for 10 minutes, the release liner was removed, and it was press-bonded for 10 minutes under a pressure of 1.0 MPa using a hot press device heated to 80°C on a blue glass plate with a width of 50 mm × a length of 80 mm × a thickness of 0.5 mm. After the above press-bonding, it was left to heat at 80°C for 1 hour, and the one left in a 23°C environment for 30 minutes or more and then cooled was used as a test sample.

[0228] For the obtained test samples, a thermal shock test from -20°C to 70°C was carried out using a small thermal shock device (manufactured by ESPEC, model TSE-11-A). The holding times at -20°C and 70°C were each 30 minutes, and the temperature increase and decrease from -20°C to 70°C and from 70°C to -20°C were within 5 minutes. One thermal cycle from -20°C to 70°C was defined as one cycle, and after 500 cycles were carried out, the appearance change was evaluated according to the following criteria. (Criteria) 〇: No appearance change was observed. ×: Cracks occurred and the glass cracked. Or, the glass floated or peeled off from the adhesive sheet.

[0229] [Crush resistance test (test to observe the shape and thickness stability of the adhesive sheet before curing)] The adhesive sheets obtained in the examples and comparative examples were cut into 5 cm × 5 cm, one release liner was peeled off, and it was press-bonded at the center of a release liner with a thickness of 50 μm cut into 7 cm × 7 cm for 10 seconds under a pressure of 0.05 MPa in a temperature environment of 23°C and bonded to prepare a test piece.

[0230] From above the above test piece, it was left in each temperature environment of 23°C for 24 hours under a pressure of 0.1 MPa per unit area. Next, the ratio of the thickness change of the adhesive sheet after leaving to the thickness of the adhesive sheet before leaving (thickness of the adhesive sheet after leaving / thickness of the adhesive sheet before leaving) was evaluated according to the following criteria. (Criteria) ◎: The ratio of the thickness of the adhesive sheet after leaving to the thickness of the adhesive sheet before leaving was 99% or more and less than 101% (no change). ○: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was 96% or more and less than 99%. △: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was 93% or more and less than 96%. ×: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was less than 93%.

[0231] [Method for evaluating the followability after active energy ray irradiation (method for evaluating the step followability when a force is applied to the unevenness and deflection of the adherend surface of the adhesive sheet after UV irradiation)] The adhesive sheets obtained in the examples and comparative examples were cut into 5 cm × 5 cm to obtain test pieces. Next, one release sheet of the test piece was peeled off and press-bonded at a pressure of 0.05 MPa for 10 seconds at the center of a 7 cm × 7 cm release liner C with a thickness of 50 μm at a temperature environment of 23°C and bonded.

[0232] After leaving the above-mentioned adherend in a temperature environment of 23°C for 60 minutes, it was irradiated with ultraviolet rays having an intensity of 100 mW / cm2 for 10 seconds using an electrodeless lamp (fusion lamp H bulb). After leaving the adherend after the above-mentioned ultraviolet ray irradiation in a temperature environment of 23°C for 10 minutes, it was press-molded for 10 seconds under pressure of 0.5 MPa using a hot press device heated to 80°C. The ratio of the thickness change of the adhesive sheet after hot pressing to the thickness of the adhesive sheet before hot pressing (thickness of the adhesive sheet after hot pressing / thickness of the adhesive sheet before hot pressing) was evaluated according to the following criteria. (Criteria) ○: The ratio of the thickness of the adhesive sheet after hot pressing to the thickness of the adhesive sheet before hot pressing was less than 90%. ×: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was 90% or more and less than 100% (no change).

[0233] [Method for evaluating the bondability to a member that does not transmit active energy rays] The adhesive sheets obtained in the examples and comparative examples were cut into pieces of 10 mm in width and 10 mm in length. One of the release liners was removed, and they were press-bonded at a pressure of 0.05 MPa for 10 seconds onto an aluminum plate with a smooth surface, 15 mm in width, 150 mm in length, and 0.05 mm in thickness, under a temperature environment of 23°C.

[0234] After leaving the above adherends under a temperature environment of 23°C for 60 minutes, they were irradiated with ultraviolet rays of 100 mW / cm 2 intensity for 10 seconds using an electrodeless lamp (fusion lamp H bulb). At this time, the above ultraviolet irradiation was performed without removing the release liner.

[0235] Next, after leaving the adherends after the above ultraviolet irradiation under a temperature environment of 23°C for 10 minutes, the release liners were removed, and they were press-bonded at a pressure of 0.5 MPa for 10 minutes using a hot press device heated to 70°C onto an aluminum plate with a smooth surface, 15 mm in width, 150 mm in length, and 0.05 mm in thickness. The laminate after the above press-bonding was heated and left at 80°C for 1 hour, and then left in a 23°C environment for 30 minutes or more and cooled to obtain a test sample. The aluminum plate used in this evaluation is a light-impermeable material with a light transmittance of 0%.

[0236] In the above test sample, both ends of the adherend were chucked respectively, and the shear adhesive strength [MPa] of the above test sample was determined by conducting a tensile test in the 180-degree direction at a tensile speed of 10 mm / min using a tensile testing machine.

[0237] The evaluation results are shown in the following table.

[0238]

Table 1

[0239]

Table 2

[0240]

Table 3

[0241]

Table 4

[0242]

Table 5

[0243]

Table 6

[0244] The adhesive sheet of the example in which the content of the thermoplastic resin (B) in the adhesive layer is within a predetermined range had good followability after active energy ray irradiation, and the results of the heat cycle test were also good. On the other hand, for the adhesive sheets of the comparative examples in which the content of the thermoplastic resin (B) deviated from the predetermined range, for the adhesive sheet of Comparative Example 1 and the adhesive sheet of Comparative Example 2 in which the filler content exceeded the predetermined range, cracks occurred and the glass cracked, or the glass floated or peeled off from the adhesive sheet due to the heat cycle test. Furthermore, the adhesive sheet of Comparative Example 4 that did not simultaneously contain the photocurable resin (A) having a polymerizable functional group other than the polymerizable unsaturated double bond, the thermoplastic resin (B) having a polymerizable functional group other than the polymerizable unsaturated double bond, and the photopolymerization initiator (C) had poor followability after active energy ray irradiation.

Claims

1. A photocurable resin (A) having a polymerizable functional group other than a polymerizable unsaturated double bond, A thermoplastic resin (B) having a polymerizable functional group other than a polymerizable unsaturated double bond, A photoinitiator (C), An adhesive layer containing the above is provided, The photocurable resin (A) has a photocationically polymerizable and / or photoanionically polymerizable functional group, The thermoplastic resin (B) is a urethane resin The adhesive layer contains, as the photocurable resin (A), one or more photocurable resins (a1) in which the temperature at which the loss tangent after curing shows a maximum value is 100°C or higher, An adhesive sheet in which the content of the thermoplastic resin (B) in the adhesive layer is in the range of 15% by mass to 50% by mass.

2. The ratio of the content of the thermoplastic resin (B) to the total content of the photocurable resin (A) and the thermoplastic resin (B) in the adhesive layer is in the range of 25% by mass to 68% by mass. The adhesive sheet according to Claim 1.

3. The absolute value of the difference between the storage modulus E'1 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of -20°C and the storage modulus E'2 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of 70°C is 1×109 Pa or less. The adhesive sheet according to Claim 1 or 2.

4. The absolute value of the difference between the loss tangent tanδ1 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of -20°C and the loss tangent tanδ2 of the cured adhesive layer measured at a frequency of 1.0 Hz and a temperature of 70°C is 1 or less. The adhesive sheet according to any one of Claims 1 to 3.

5. The photocurable resin (A) has at least one photocationically polymerizable functional group selected from the group consisting of one or more epoxy groups, oxetanyl groups, hydroxyl groups, vinyl ether groups, episulfide groups, ethyleneimine groups, and oxazoline groups in one molecule. The adhesive sheet according to any one of Claims 1 to 4.

6. The thermoplastic resin (B) has at least one polymerizable functional group selected from the group consisting of isocyanate groups, hydroxyl groups, oxetanyl groups, and epoxy groups. The adhesive sheet according to any one of Claims 1 to 5.

7. The photocurable resin (A) and the thermoplastic resin (B) react with each other. The adhesive sheet according to any one of Claims 1 to 5.

8. The adhesive sheet according to any one of claims 1 to 7, wherein the photoinitiator (C) is a photo cationic polymerization initiator.

9. The adhesive layer contains, as the photocurable resin (A), one or more photocurable resins (a1) in which the temperature at which the loss tangent after curing exhibits a maximum value is 105°C or higher and 250°C or lower. The adhesive sheet according to any one of claims 1 to 8.

10. The adhesive layer contains one or more room temperature solid epoxy resins and one or more room temperature liquid epoxy resins. The adhesive sheet according to any one of claims 1 to 9.

11. An adhesive sheet according to any one of claims 1 to 10, a first member bonded to the first main surface of the adhesive sheet, a second member bonded to the second main surface of the adhesive sheet, and a laminate having the same.

12. The laminate according to claim 11, which is used in an image display device.

13. A method for manufacturing a laminate using the adhesive sheet according to any one of claims 1 to 10, a step [1] of bonding a first adherend to the first main surface of the adhesive sheet, a step [2] of bonding a second adherend to the second main surface of the adhesive sheet, and a step [3] of curing the adhesive sheet, and further includes a step of irradiating the first main surface or the second main surface of the adhesive sheet with active energy rays before the step [1] or between the step [1] and the step [2]. A method for manufacturing a laminate.

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