JP7069830B2 - Adhesive sheet, article and manufacturing method of article - Google Patents

Description

The present invention relates to an adhesive sheet and an article to which the adhesive sheet is attached and a method for manufacturing the article.

Resin molded products used for the exterior of home appliances, the exterior of mobile terminals, the interior and exterior of automobiles, etc. are parts molded in three dimensions by injection molding, extrusion molding, or the like. A hard coat layer, a mat layer, etc. are laminated on the surface of these molded products by direct application to the surface of the molded product for the purpose of preventing scratches, or a hard coat layer, a mat layer, etc. are laminated on the surface. The laminated members are laminated by a method of welding resins to each other when a molded product is molded by an injection in-mold molding machine, a method of applying a liquid adhesive or the like to the back surface of the bonded member, and the like. In recent years, in order to improve the appearance quality such as the smoothness of the surface of the hard coat layer and the uniformity of the layer thickness, and to support small lot production, the hard coat layer, the mat layer, etc. are not directly laminated on the molded product. There are many construction methods in which a bonding member having a hard coat layer laminated on the surface thereof is bonded to the surface of the molded product (for example, Patent Document 1). In addition, in the welding of resins between resins by an injection in-mold molding machine, air bubbles tend to collect in the gap between the bonded member and the molded product, so liquid adhesive or the like is applied to the back surface of the bonded member and laminated by a method of bonding. In many cases. In this case, the bonding member is formed by applying an adhesive to the surface of one side, heating the bonding member to about 100 to 160 ° C. using a vacuum / pressure bonding machine, and then pressing the molded product against the bonding member. In some cases, a method of bonding to the surface of a molded product may be adopted while stretching the bonding member.

In the method of applying a liquid adhesive that cures with heat or moisture to the back surface of the bonded member, it takes about 24 hours from the time the liquid adhesive is applied until the curing is completed. There are problems that the bonded member floats or peels off during curing, and that the liquid adhesive flows when the bonded member is stretched by the molding machine and the layer thickness is likely to change.

In the case of adhesives and adhesive sheets whose curing reaction proceeds by heat, the temperature of the molded product to be attached is about 100 ° C because it is a material with poor heat resistance such as polycarbonate, polymethylmethacryl, and acrylonitrile-butadiene-styrene. It was sometimes difficult to cure at temperatures above. Further, in the case of an adhesive or an adhesive sheet whose curing reaction proceeds at a temperature of about 100 ° C. or lower, the storage stability is extremely inferior, and refrigerated storage or frozen storage is required.

Further, when an ultraviolet curing reaction type adhesive or an adhesive sheet (for example, Patent Document 2) is used, ultraviolet rays reach the adhesive layer by a decorative printing layer printed on the front surface or the back surface of the bonding member. There is a problem that there are some difficult parts, and when a transparent sheet made of a light-resistant resin is used, it is difficult for ultraviolet rays to pass through, so that ultraviolet rays cannot be cured.

In addition, when the bonding member is bonded with a thermoplastic adhesive tape, the elastic coefficient of the adhesive does not change while it is low, and when the bonding member is bonded to the surface of the molded product while being heated and stretched. When left in a moist heat environment for the subsequent evaluation of the reliability of the molded product, swelling or floating occurs due to outgas from the bonded member or the molded product, or the residue remains when the bonded member is stretched. There was a problem that swelling and floating were likely to occur due to stress. Further, in order to suppress the generation of outgas from the bonded member or the molded product, a step of preheating these members to release the gas is required, which is inferior in production efficiency (for example, Patent Document 3). ..

Japanese Unexamined Patent Publication No. 2014-092580 JP-A-2015-072343 Japanese Unexamined Patent Publication No. 2014-205335

The problem to be solved by the present invention is to suppress swelling and floating of the bonded member caused by outgas from the surface of the molded product, residual stress of the bonded member, and the like, and to prevent the active energy rays from penetrating. It is intended to provide an adhesive sheet that can be attached to an adherend and a bonded molded product.

The present inventor has found that the above problems can be solved by an adhesive sheet having an adhesive layer having various tensile elastic moduli.
That is, the present invention is an adhesive sheet used for bonding two or more adherends having a surface through which active energy rays do not pass, and at 25 ° C. before irradiating the surface of the adhesive layer with active energy rays. The tensile storage elastic modulus of the adhesive layer is 1 × 10 ³ to 1 × 10 ⁶ Pa, and the tensile storage elastic modulus of the adhesive layer at 25 ° C. after irradiating the surface of the adhesive layer with active energy rays is 1 × 10 It is ³ to 1 × 10 ⁶ Pa, and provides an adhesive sheet having a tensile storage elastic modulus of 2 × 10 ⁴ Pa or more at 100 ° C. after the curing reaction.

The adhesive sheet of the present invention suppresses swelling and floating of the bonded member caused by outgas from the surface of the molded product, residual stress of the bonded member, etc., and has a surface through which active energy rays do not pass. Since it can be attached to the body, it can greatly contribute to the production of resin molded products used for the exterior of home appliances, the exterior of mobile terminals, the interior and exterior of automobiles, and the like.

The adhesive sheet of the present invention is an adhesive sheet used for bonding two or more adherends having a surface through which active energy rays do not pass, and is 25 ° C. before irradiating the surface of the adhesive layer with active energy rays. The tensile storage elasticity of the adhesive layer is 1 × 10 ³ to 1 × 10 ⁶ Pa, and the tensile storage elasticity of the adhesive layer at 25 ° C. after irradiating the surface of the adhesive layer with active energy rays is 1 ×. It is 10 ³ to 1 × 10 ⁶ Pa, and the tensile storage elasticity of the adhesive layer at 100 ° C. after the curing reaction is 2 × 10 ⁴ Pa or more.

(Storage modulus)
The adhesive sheet of the present invention has a tensile storage elastic modulus of 1 × 10 ³ to 1 × 10 ⁶ Pa at 25 ° C. before irradiation with active energy rays, and a tensile modulus of the adhesive layer at 25 ° C. after irradiation with active energy rays. Use an adhesive sheet having a storage elastic modulus of 1 × 10 ³ to 1 × 10 ⁶ Pa and a tensile storage elastic modulus of 2 × 10 ⁴ Pa or more at 100 ° C. after the curing reaction.

The tensile storage elastic modulus of the adhesive layer at 25 ° C. before irradiation with the active energy rays is preferably 1 × 10 ⁴ to 5 × 10 ⁵ Pa, and is pressure-sensitive without heating to the first adherend. It is more preferably 5 × 10 ⁴ to 5 × 10 ⁵ Pa in order to be able to adhere and to suppress sticking out or crushing only from the end face when the adhesive sheet is stored.

The tensile storage elastic modulus of the adhesive layer at 25 ° C. after irradiation with the active energy rays is preferably 1 × 10 ⁴ to 5 × 10 ⁵ Pa, and is pressure-sensitive without heating to the second adherend. It can be adhered and does not become too soft when it is heat-bonded, and it is 5 × 10 ⁴ to 5 × 10 ⁵ Pa in order to suppress swelling and floating due to outgas from the first and second adherends and residual stress. Is more preferable.

The tensile storage elastic modulus of the adhesive layer at 100 ° C. after the curing reaction is preferably 5 × 10 ⁴ to 1 × 10 ¹⁰ Pa, and when it is left in a moist heat environment for a long time and the heated state is maintained, it is the first. In order to suppress swelling and floating due to outgas and residual stress from the first and second adherends, 1 × 10 ⁵ to 1 × 10 ⁹ Pa is more preferable.

The tensile storage elastic modulus of the adhesive layer at 25 ° C. after the curing reaction is preferably more than 1 × 10 ⁶ and preferably 1 × 10 ¹² Pa or less, from the first and second adherends bonded. 1 × 10 ⁷ to 1 × 10 ¹⁰ Pa is more preferable in order to obtain high bonding strength and resistance to peeling in the usage environment of the molded product.

The tensile storage elastic modulus is measured by the dynamic viscoelastic spectrum of the tensile. Using the viscoelasticity measuring machine "RSA III" manufactured by TA Instruments, in tension mode, under the conditions of frequency 1 Hz, temperature rise rate 3 ° C / min, load strain 0.05%, -40 to 150. The tensile storage elastic modulus (E') in the temperature range up to ° C. is measured.

(Resin composition)
The adhesive layer of the adhesive sheet of the present invention is preferably made of a resin composition containing at least one polymerizable resin.

(Polymerizable resin)
Examples of the polymerizable resin include a resin obtained by copolymerizing a monomer having a polymerizable functional group such as an acrylic resin, a urethane resin, a phenol resin, and a polyester resin, and among them, an acrylic resin having excellent adhesive strength is used. It is preferable to do so.
As the acrylic resin, a resin obtained by polymerizing a monomer component containing a (meth) acrylic monomer or the like can be used.

Examples of the (meth) acrylic monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, and n-hexyl ( It has an alkyl group having 1 to 14 carbon atoms such as meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. (Meta) acrylate can be used, it is preferable to use (meth) acrylate having an alkyl group having 4 to 9 carbon atoms, and it is more preferable to use ethyl acrylate or n-butyl acrylate alone or in combination. .. It is easy to adjust the tensile storage elasticity of the adhesive layer after irradiation with active energy rays to the above range, suppress the swelling and floating of the adhesive sheet when heat-bonding, and the phase when other polymerizable resins are used together. In order to improve the solubility, it is more preferable to use 50% by mass or more of ethyl acrylate having 2 carbon atoms, which is less affected by the steric hindrance of the alkyl group.

The (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms is used in the range of 60 to 95% by mass with respect to the total amount of the monomer components used in the production of the acrylic polymer. It is preferable, and it is more preferable to use it in the range of 80 to 90% by mass in order to enable pressure-sensitive adhesion to the first and / or second adherends without heating and to increase the adhesive strength after the curing reaction. ..

The (meth) acrylic monomer has a cationically polymerizable functional group such as an epoxy group, an oxetanyl group, a vinyl ether group, an episulfide group, an ethyleneimine group, and an oxazoline group, in addition to the above-mentioned ones. It is preferable to use a weight, and in particular, the one having an epoxy group and / or an oxetanyl group is less likely to cause a rapid curing reaction when the surface of the adhesive layer of the adhesive sheet is irradiated with active energy rays. It is preferable for maintaining the pressure-sensitive adhesiveness of 2 to the adherend.

Specific examples of the vinyl monomer having an epoxy group and / or an oxetanyl group include glycidyl acrylate having an epoxy group, glycidyl methyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, and oxetanyl group (3-ethyloxetane). -3-yl) Methyl acrylate, 3,4-epoxide cyclohexylmethyl methacrylate and the like can be used, and among them, glycidyl acrylate and glycidyl methyl methacrylate having an epoxy group can be used, and the adhesive layer after the curing reaction can be used. The tensile storage elasticity of the epoxide is adjusted to the above range so that it does not become too soft, and is particularly preferable in suppressing swelling and floating due to outgas and residual stress from the adherend when left in a moist heat environment.

The epoxy equivalent of the acrylic copolymer is 500 to 20,000 g / eq. It is preferably in the range of 2,000 to 15,000 g / eq. More preferably, it is in the range of 5,000 to 12,000 g / eq. By using the one in the range of, the tensile storage elastic modulus of the adhesive layer after the curing reaction is adjusted to the above range to prevent it from becoming too soft, and the volume shrinkage is small during the curing reaction, and strain remains at the adhesive interface. It is more preferable to prevent the adhesive strength from being lowered.

When another polymerizable resin having an epoxy group is used in combination, it is preferable that the total epoxy equivalent is in the above range.

The total epoxy equivalent is calculated by calculating the molecular weight of the total vinyl monomer per mol of the epoxy group for the resin having each epoxy group [g / eq. ] Is calculated, and it is calculated by multiplying the usage fraction of the resin having each epoxy group. As a specific example, in the case of a resin composition consisting of a resin A having an epoxy group, a resin B, and a resin C not containing an epoxy group, the total epoxy equivalent is calculated from the following formula 1. In this case, other additive components and diluting solvents described later are not included in the calculation.
Mass part of resin A having an epoxy group in the resin composition: x [mass part]
Mass part of resin B having an epoxy group in the resin composition: y [mass part]
Mass part of resin C having no epoxy group in the resin composition: z [mass part]
Epoxy equivalent of resin A having an epoxy group in the resin composition: α [g / eq. ]
Epoxy equivalent of resin B having an epoxy group in the resin composition: β [g / eq. ]
Equation 1: Total epoxy equivalent [g / eq. ] = (Α × x + y × β) / (x + y + z)

As for the amount of the vinyl monomer having an epoxy group and / or an oxetanyl group, it is preferable to adjust the amount to be used so that the total of the epoxy equivalents is within the above range. When the acrylic copolymer is used alone as the polymerizable resin, it is preferably used in the range of 0.7 to 25% by mass, and it is preferably used in the range of 5 to 15% by mass after the curing reaction. It is more preferable to adjust the tensile storage elastic modulus of the adhesive layer to the above range so that the adhesive layer does not become too soft, and the volume shrinkage is small during the curing reaction, and strain remains at the adhesive interface to prevent the adhesive strength from being lowered. ..

When another polymerizable resin described later is used in combination with the acrylic copolymer, it is more preferable to use it in the range of 0.2 to 5% by mass, and it is used in the range of 0.4 to 3% by mass. By adjusting the tensile storage elastic modulus of the adhesive layer after the curing reaction to the above range, the adhesive layer does not become too soft, and the volume shrinkage due to the curing reaction is small, and strain remains at the adhesive interface to reduce the adhesive strength. It is more preferable to suppress the causing.

As the (meth) acrylic monomer, it is preferable to use a highly polar (meth) acrylic monomer in addition to the above-mentioned one, and it is more preferable to use a nitrogen-containing vinyl monomer.

As the nitrogen-containing vinyl monomer, it is preferable to use a nitrogen-containing vinyl monomer having an amino group, an amide group, a nitrile group, etc. Among them, the nitrogen-containing vinyl monomer has an amide group and a nitrile group. It is easy to adjust the tensile storage elasticity of the adhesive layer after irradiation with active energy rays to the above range, and pressure-sensitive adhesion can be achieved without heating to the second adherend, and the above-mentioned It is more preferable to increase the internal cohesive force of the acrylic copolymer, prevent it from becoming too soft when it is heat-bonded, and suppress swelling and floating due to outgas and residual stress from the first and second adherends.

Examples of the nitrogen-containing vinyl monomer include N-vinyl-2-pyrrolidone, N-vinylcaprolactam, acrylonitrile, acryloylmorpholine, dimethylaminoethylacrylate, N, N-dimethylacrylamide, N, N-diethylacrylamide, and N-isopropyl. Examples thereof include acrylamide, dimethylaminopropyl acrylamide, diacetone acrylamide and the like. The nitrogen-containing vinyl monomer is preferably 0.5 to 40% by mass, more preferably 5 to 20% by mass, based on the total amount of the monomer components used in the production of the acrylic polymer. Preferably, the content is 8 to 15% by mass, which makes it easy to adjust the tensile storage elastic modulus of the adhesive layer after irradiation with active energy rays to the above range, and pressure-sensitive adhesion can be performed without heating to the second adherend. , It is more preferable to increase the internal cohesive force of the acrylic copolymer, not to be too soft when heat-bonded, and to suppress swelling and floating due to outgas and residual stress from the first and second adherends. ..

In the curing method using active energy rays, when the acrylic copolymer is cured by a cationic polymerization reaction, the acrylic copolymer includes 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl. It is preferable not to use a (meth) acrylic monomer having a hydroxyl group such as (meth) acrylate and 6-hydroxyhexyl (meth) acrylate. When the (meth) acrylate having a hydroxyl group is used, the cationic polymerization reaction proceeds immediately after the irradiation with the active energy ray, and the tensile storage elasticity of the adhesive layer after the irradiation with the active energy ray exceeds the above range. It becomes hard and it becomes difficult to attach the adhesive sheet to the surface of the second adherend. The amount of the (meth) acrylic monomer having a hydroxyl group is preferably 0.05% by mass or less with respect to the total amount of the vinyl monomer component.

The acrylic copolymer can be produced by polymerizing the monomer component by a known method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method, and in particular, a suspended weight. It is preferable to legally produce the adhesive sheet in order to narrow the molecular weight distribution, enhance the compatibility when the other polymerizable resin is used in combination, and obtain the transparency of the obtained adhesive sheet.

As the acrylic copolymer, those having a weight average molecular weight in the range of 10,000 to 1,000,000 are preferably used, and those having a weight average molecular weight in the range of 100,000 to 500,000 are those before and after irradiation with active energy rays. It is easy to adjust the tensile storage elastic modulus of the adhesive layer to the above range, pressure-sensitive adhesion can be performed without heating to the first and second adherends, and it does not become too soft when heat-bonded. It is more preferable to suppress swelling and floating due to outgas and residual stress from the second adherend. Further, when another polymerizable resin is used in combination, it is more preferable to enhance the compatibility and maintain the transparency of the adhesive sheet.

The weight average molecular weight can be measured by a gel permeation chromatograph (GPC). More specifically, it can be obtained by measuring with the following GPC measuring conditions by the polystyrene conversion value using "SC8020" manufactured by Tosoh Corporation as a GPC measuring device.
(GPC measurement conditions)
-Sample concentration: 0.5% by mass (tetrahydrofuran solution)
-Sample injection amount: 100 μL
-Eluent: Tetrahydrofuran (THF)
・ Flow velocity: 1.0 mL / min
-Column temperature (measurement temperature): 40 ° C
-Column: "TSKgel GMHR-H" manufactured by Tosoh Corporation
・ Detector: Differential refractometer

It is preferable to use a resin having a glass transition temperature of -30 to 50 ° C. for the acrylic copolymer, and the one having a glass transition temperature of -10 to 30 ° C. determines the tensile storage elastic modulus of the adhesive layer before and after irradiation with active energy rays. It is easy to adjust to the range, it can be pressure-sensitively adhered to the first and second adherends in an environment of 25 ° C or higher, and it does not become too soft for heat bonding, and it is from the first and second adherends. It is more preferable to suppress swelling and floating due to outgas and residual stress. The glass transition temperature is obtained by molding the acrylic copolymer alone into a sheet by the method described later, and is measured by the dynamic viscoelasticity spectrum of tensile force. Using the viscoelasticity measuring machine "RSA III" manufactured by TA Instruments, in tension mode, under the conditions of frequency 1 Hz, temperature rise rate 3 ° C / min, load strain 0.05%, -40 to 150 ° C. The storage viscoelasticity (E') and the loss tangent are measured in the temperature range up to, and the peak temperature of the loss tangent is defined as the glass transition temperature of the acrylic copolymer.

In addition to the polymerizable resin, one or more other polymerizable resins may be used in combination in order to adjust the tensile storage elastic modulus within the above range.

The other polymerizable resin may have one or more cationically polymerizable functional groups such as an epoxy group, an oxetanyl group, a vinyl ether group, an episulfide group, an ethyleneimine group, and an oxazoline group in one molecule. preferable. Above all, it is preferable to use a polymerizable resin having an epoxy group in order to obtain high curing reactivity and high bonding strength after the curing reaction. As the polymerizable resin having an epoxy group, a compound having one or more epoxy groups in one molecule can be used. As specific examples, 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, tetraphenyl Etan type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, phenol aralkyl type epoxy resin, naphthol novolak type epoxy resin, naphthol aralkyl type epoxy resin, naphthol-phenol co-shrink novolak type epoxy resin, naphthol-cresol co-shrink novolak Type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy resin, biphenyl modified novolak type epoxy resin, trimetylol propane type epoxy resin, alicyclic epoxy resin, acrylic resin with epoxy group, polyurethane resin with epoxy group , A polyester resin having an epoxy group, an epoxy resin having flexibility, and the like can be used. As the polymerizable resin having an epoxy group, trimethylolpropane type epoxy resin and alicyclic epoxy resin are used alone or in combination to increase the crosslink density and the elasticity of the adhesive layer after the curing reaction. It is more preferable to increase the rate and adhesive strength, and to suppress swelling and floating due to outgas and residual stress from the molded product when left in a moist heat environment.

As the other heavy synthetic resin, it is preferable to use a semi-solid resin having a softening point of 25 ° C. or lower, or a liquid resin at 25 ° C., and a resin having a B-type viscosity at 25 ° C. of 100,000 mPa or less. It is more preferable to use a resin of 1,000 mPa or less so that the tensile storage elasticity of the adhesive layer before and after irradiation with active energy rays can be easily adjusted within the above range when used in combination with the acrylic copolymer. It can be pressure-sensitively adhered to the first and second adherends without heating, and the amount of other polymerizable resins used can be suppressed to a small amount, and it does not become too soft when heat-bonded. It is more preferable to suppress swelling and floating due to outgas and residual stress from the adherend of 2.

The epoxy equivalents of the other heavy synthetic resins can be arbitrarily adjusted as long as the total epoxy equivalents are within the above range, and among them, 50 to 1,000 g / eq. It is preferably 100 to 300 g / eq. This improves the tensile storage elastic modulus of the adhesive layer after the curing reaction, and swelling and floating due to outgas and residual stress from the first and second adherends when left in a moist heat environment. It is more preferable to suppress the above.

As the other heavy synthetic resin, it is preferable to use one having a weight average molecular weight in the range of 50 to 1,000, and one having a weight average molecular weight in the range of 100 to 500 is the acrylic copolymer. It is more preferable to enhance the compatibility of the adhesive sheet, maintain the transparency of the adhesive sheet, and suppress the exudation of the adhesive sheet from the adhesive layer during heat bonding after irradiation with active energy rays.

The amount of the other polymerizable resin used can be arbitrarily adjusted as long as the total epoxy equivalent is within the above range with respect to the acrylic copolymer, and among them, 5 to 60% by mass is used. It is preferable to use 20 to 50% by mass, which suppresses exudation of the adhesive sheet from the adhesive layer during heat bonding after irradiation with active energy rays, increases the crosslink density, and is used after the curing reaction. It is more preferable for improving the tensile storage elasticity of the adhesive layer and suppressing swelling and floating due to outgas and residual stress from the first and second adherends when left in a moist heat environment.

(Polymer initiator)
The initiator used for the curing reaction of the adhesive layer of the adhesive sheet of the present invention may be any as long as it is activated by an external stimulus. For example, when the cationically polymerizable compound is used, it is cationically polymerizable. It is preferable to use one having a functional group capable of reacting with the functional group of.

Further, the polymerization initiator includes a photopolymerization initiator and a thermal polymerization initiator, which may be used alone or in combination of two. Above all, in order to obtain a reaction at a low temperature and a good curing reaction, it is preferable to use a photopolymerization initiator in which the reaction proceeds by light rays as an external stimulus. As a result, high bonding strength is obtained without damaging the members to be laminated or by causing distortion between the first and second adherends, thereby deforming the adherend and causing cracks in the adherend. Can be done.

As the light, an appropriate light ray type such as ultraviolet rays or visible light can be used, but it is preferable to use light rays having a wavelength of 300 nm or more and 420 nm or less.

The photopolymerization initiator may be any one as long as it is activated by light rays, and examples thereof include a photoradical polymerization initiator, a photocationic polymerization initiator, and a photoanionic polymerization initiator. When a cationically polymerizable compound is used, it is preferable to use a photocationic polymerization initiator.

The photocationic polymerization initiator is not particularly limited as long as it can induce a ring-opening reaction of a cationically polymerizable functional group by a light beam having a wavelength of 300 to 370 nm. Compounds that induce a ring-opening reaction of a cationically polymerizable functional group and are inactive in a wavelength region exceeding 370 nm are preferably used, and examples of such compounds include aromatic diazonium salts, aromatic iodonium salts, and aromatics. Examples include onium salts such as group sulfonium salts.

Specific examples of such 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 of which are manufactured by ADEKA). IGM Resin), IRGACURE290 (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 (Both are manufactured by Sun Appro) and the like.

The photocationic polymerization initiator may be used alone or in combination of two or more. Further, a plurality of photocationic polymerization initiators having different effective active wavelengths may be used for two-step curing.

The photocationic polymerization initiator may be used in combination with an anthracene-based or thioxanthone-based sensitizer, if necessary.

The blending ratio of the photocationic polymerization initiator is preferably in the range of 0.001 part by mass to 30 parts by mass, and 0.01 to 20 parts by mass with respect to 100 parts by mass of the photocationic polymerization initiator. It is preferably used in the range, and more preferably in the range of 0.1 to 10 parts by mass in order to adjust the tensile storage elasticity of the adhesive layer after irradiation with active energy rays to the above range. If the blending ratio of the photocationic polymerization initiator is too small, the crosslink density after the curing reaction is insufficient, the tensile storage elastic modulus of the adhesive layer is out of the above range, and swelling and floating in a moist heat environment are suppressed. On the other hand, if the required bonding strength is insufficient, the cationic polymerization reaction of the adhesive layer after irradiation with active energy rays rapidly proceeds, the tensile storage elastic modulus deviates from the above range, and the second adherend is attached. The time for pressure-sensitive adhesion may be too short.

The adhesive layer of the adhesive sheet of the present invention increases the crosslink density after the curing reaction, adjusts the storage elastic modulus to the above range, and suppresses swelling and floating in a moist heat environment. After being heat-bonded to the adherend of the above, a post-curing step may be performed. The condition for leaving the post-curing step is preferably 100 ° C. or lower, and it is more preferable to go through the post-curing step at 80 ° C. or lower for about 1 hour in order to suppress deformation of the first and second adherends due to heat. ..

In addition to the above resin composition, other additives include an adhesion promoter, a surface conditioner, a leveling agent, a defoaming agent, a plasticizer, a tackifier resin, an antioxidant, a light stabilizer, an antioxidant, and a thickening agent. Additives such as agents and known catalysts for controlling the curing reaction can be used as needed.

The molded parts to which the adhesive sheet of the present invention is attached are used to pass microwaves such as automobile emblems and electromagnetic waves such as millimeter waves, and high-frequency electric pulses such as flexible printed circuit boards are passed in the vicinity to transmit electrical signals. For reading purposes, a polyolefin resin, an inorganic filler, or the like may be added for the purpose of adjusting the dielectric constant contact and the relative permittivity of the adhesive sheet.

The polyolefin resin is preferably an olefin resin such as a polyethylene resin or a polypropylene resin having a specific dielectric constant of about 2 to 3, a rubber resin such as an isoprene resin or a butadiene resin, and a phase with the thermoplastic resin or the liquid resin. For the purpose of improving the solubility, a part of the side chain may be chlorinated or modified with a carboxylic acid to partially improve the polarity. Further, by introducing an epoxy group, an oxetanyl group, or the like into the molecule of the polyolefin resin, it is incorporated into the curing reaction system, which is preferable for increasing the tensile storage elastic modulus of the adhesive layer after the curing reaction.

As the inorganic filler, it is preferable to use an inorganic filler such as boron nitride, forteslite, cordierite, silica, magnesium oxide, alumina, etc., which has a dielectric constant contact of about ^10-4 to ^10-5 , and is preferably used with the mixed composition. It is more preferable to use silica, which has excellent compatibility with the above and can enhance the transparency of the adhesive sheet.

As the inorganic filler, an arbitrary shape such as a spherical shape or a crushed shape can be used, and in order to enhance compatibility with the polymerizable resin, a titanate coupling, an aluminate coupling, or a silane coupling is provided on the surface. You may use the surface-treated material such as.

As for the amount of the polyolefin resin or inorganic filler used, it is preferable to use 1 to 50 parts by mass in total with respect to 100 parts by mass of the polymerizable resin, and it is preferable to use 5 to 20 parts by mass of the specific dielectric of the adhesive sheet. It is more preferable because it is possible to suppress the decrease in pressure-sensitive adhesiveness to the surface of the adherend and the decrease in adhesiveness after the curing reaction while reducing the rate and the dielectric direct contact.

As the particle size of the inorganic filler, it is preferable to use one having a particle size of 50% under an integrated sieve having a particle size of 10 nm to less than 50 μm, and more preferably one having a particle size of 10 nm to 20 μm. It is particularly preferable to use the above-mentioned adhesive sheet in order to enhance the transparency of the adhesive sheet and to achieve both good dispersibility of the inorganic filler and ease of coating. For the 50% particle size distribution under the integrated sieve of the inorganic filler, use a laser diffraction type particle size distribution measuring instrument SALD-3100 manufactured by Shimadzu Corporation, and use a numerical value measured using isopropanol as a dispersion medium. Can be done.

Examples of the solvent include ester solvents such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate, ketone solvents such as acetone, methyl ketyl ketone, methyl isobutyl ketone, diisobutyl ketone and cyclohexanone, and toluene and xylene. Aromatic hydrocarbon solvents and the like can be used.

(Adhesive sheet)
The adhesive layer of the adhesive sheet of the present invention can be produced by molding a resin composition in which a polymerizable resin, a polymerization initiator, other additives, a solvent and the like are uniformly mixed into a sheet shape.

When the above-mentioned components are mixed to produce the above-mentioned resin composition, a dissolver, a butterfly mixer, a BDM twin-screw mixer, a planetary mixer and the like can be used, and a dissolver and a butterfly mixer can be used. Preferably, when the inorganic fillers are used, it is preferable to use a planetary mixer in order to improve their dispersibility. In addition, in the process of manufacturing the adhesive sheet, in order to suppress pinholes generated during solvent drying and not to deteriorate the transparency and adhesive performance of the adhesive sheet, decompression defoaming, centrifugal defoaming, etc., as necessary. A mixer or a liquid feed pump having the defoaming function of the above may be used.

The adhesive sheet of the present invention is the adhesive of the present invention, for example, by applying a resin composition uniformly mixed with the polymerizable resin, a polymerization initiator, other components, a solvent, etc. to the surface of a release liner and drying the resin composition. Sheets can be manufactured.

It is preferable to carry out the drying at a temperature of preferably about 40 to 120 ° C., more preferably about 50 to 90 ° C. in order to suppress the progress of the curing reaction by the polymerization initiator.

Examples of the release liner include paper such as kraft paper, glassin paper, and high-quality paper, resin films such as polyethylene, polypropylene (OPP, CPP), and polyethylene terephthalate, and laminated paper in which the paper and the resin film are laminated. Paper that has been sealed with clay or polyvinyl alcohol, etc., that has been peeled off from silicone-based resin, etc. on one or both sides can be used, and the resin film and silicone-based resin, etc. are peeled off. It is preferable to use the above-mentioned one in order to enhance the transparency of the adhesive sheet of the present invention.

The adhesive sheet of the present invention may be sandwiched by another optional release liner until it is used in the bonding step.

The thickness of the adhesive layer of the adhesive sheet of the present invention is preferably 5 to 1,000 μm, and the adhesive sheet can be pressure-sensitively adhered to the first and second adherends in an environment of 25 ° C. or higher. It is preferably 30 to 150 μm in order to prevent the adhesive layer from sticking out during storage and the transparency from being lowered due to the thickening of the film.

Further, in order to reduce the amount of the solvent remaining after drying, two or more adhesive layers coated and dried on different release liners may be bonded to obtain an adhesive sheet having a predetermined thickness. In this case, it is preferable to bond the release liners having different peeling forces in order to suppress the separation.

The adhesive layer of the adhesive sheet of the present invention preferably has a gel content in the range of 5 to 70% by mass, preferably in the range of 20 to 50% by mass, before irradiation with active energy rays. It is easy to adjust the tensile storage elasticity of the adhesive layer before and after irradiation with active energy rays to the above range, and pressure-sensitive adhesion can be performed without heating to the first and second adherends, and heating is possible. It does not become too soft when bonded, and is more preferable in suppressing swelling and floating due to outgas from the first and second adherends and residual stress.

The gel fraction is determined by immersing the adhesive layer of the adhesive sheet of the present invention in which a release liner is laminated on one side in toluene adjusted to 23 ° C. for 24 hours, and the adhesive of the adhesive sheet remaining in the solvent. It refers to the mass of the layer after drying and the value calculated based on the following formula.

Gel fraction (% by mass) = {(mass of adhesive layer of adhesive sheet remaining without being dissolved in toluene) / (mass of adhesive layer of adhesive sheet before immersion in toluene)} x 100
The mass of the adhesive layer of the adhesive sheet constituting the adhesive sheet before immersion is a value obtained by subtracting the mass of the release liner used for manufacturing the test piece from the mass of the test piece. Further, the mass of the adhesive layer of the remaining adhesive sheet refers to a value obtained by subtracting the mass of the release liner from the mass of the residual after drying.

Further, as the adhesive layer of the adhesive sheet of the present invention, it is preferable to use one having a gel content in the range of 50 to 99% by mass after the curing reaction, and one in the range of 70 to 90% by mass. This has a high crosslink density, improves the tensile storage elastic modulus of the adhesive layer after the curing reaction, and outgas and residual stress from the first and second adherends when left in a moist heat environment. It is more preferable to suppress swelling and floating due to.

The adhesive layer of the adhesive sheet of the present invention preferably uses a resin having a glass transition temperature of −30 to 50 ° C. before irradiation with active energy rays, and a resin having a temperature of −10 to 30 ° C. is before irradiation with active energy rays. It is preferable that the tensile storage elastic modulus of the adhesive layer of No. 1 is easily adjusted within the above range and pressure-sensitive adhesion can be performed without heating to the first adherend. The glass transition temperature after curing is preferably 0 ° C. or higher, and more preferably 30 to 250 ° C. in order to suppress cracking of the adhesive layer in a cold environment and to suppress swelling and floating when left in a moist heat. .. The glass transition temperature is measured by the dynamic viscoelasticity spectrum of the adhesive layer of the adhesive sheet. Using the viscoelasticity measuring machine "RSA III" manufactured by TA Instruments, in tensile mode, under the conditions of frequency 1 Hz, temperature rise rate 3 ° C / min, load strain 0.05%, -40 to 150 ° C. The storage elastic modulus (E') and the loss tangent are measured in the temperature range up to, and the peak temperature of the loss tangent is defined as the glass transition temperature of the adhesive layer of the adhesive sheet.

In the adhesive sheet of the present invention, when a transparent resin sheet described later is used as the first adherend, it is preferable to use an adhesive sheet having a total light transmittance Tt of 80 to 99%. , It is more preferable to use one having a total light transmittance Tt of 90 to 99%. Further, as the adhesive sheet, it is preferable to use a sheet having a haze of 0 to 3%, and it is more preferable to use a sheet having a haze of 0 to 2%. An adhesive sheet having a total light transmittance Tt and haze in the above range can give an excellent appearance without damaging the design decorated on the surface of the second adherend.

For the total light transmittance Tt and haze, two polycarbonate resin sheets having a thickness of 1 mm or less, a total light transmittance Tt of 90% or more and a haze of 0.5% or less were prepared, and the release liner was removed. The surface of the adhesive layer of the adhesive sheet of the present invention is irradiated with activation energy rays, bonded to the two resin sheets so that air bubbles do not enter, and then subjected to a post-curing step at 70 ° C. for 1 hour. Refers to the total light transmittance Tt and haze when measured with an arbitrary total light transmittance meter according to JIS K7136.

In the adhesive sheet of the present invention, each peel adhesive force before and after irradiation with active energy rays is preferably 0.5 N / 20 mm or more, and 2 N / 20 mm or more is the first and second adherends. It can be pasted without any displacement of the sticking position or mixing of air bubbles, and is more preferable in suppressing swelling and floating due to outgas from the first and second adherends when the sticking is performed by heating.

Further, the peel adhesive strength of the adhesive sheet after the curing reaction is preferably 5N / 20 mm or more, and 8N / 20 mm or more is the first and second covering when left in a moist heat environment. It is more preferable to suppress swelling and floating due to outgas from the body and residual stress.

The peel adhesive force before irradiation with the active energy rays was such that a test piece bonded to a polyester film having a thickness of 50 μm was attached to one side of the adhesive sheet cut into a width of 20 mm and a length of 100 mm at 23 ° C. and 50% RH. It is attached to a polycarbonate plate with a thickness of 0.15 mm in an environment, and after one reciprocating pressurization with a 2 kg roller at a speed of 300 mm / min, a polyester film is pulled in the 180 ° direction within 1 minute at a speed of 50 mm / min. Measure the adhesive strength when the film is peeled off.

For the peel adhesive strength after irradiation with the active energy rays, the peeling liner on one side was removed from the test piece bonded to the polyester film having a thickness of 50 μm on one side of the adhesive sheet cut into a width of 20 mm and a length of 100 mm. After that, the surface of the adhesive layer was irradiated with ultraviolet rays at an intensity of 290 mW / cm ² and an irradiation amount of 500 mJ / cm ² by an ultraviolet irradiation lamp, and 20 minutes after the ultraviolet irradiation at 23 ° C. and 50% RH environment, the above-mentioned The adhesive strength is measured in the same manner.

The peel adhesive strength after the curing reaction was further applied to a polycarbonate plate having a thickness of 0.15 mm 20 minutes after irradiation with ultraviolet rays, and one reciprocating pressurization was performed with a 2 kg roller at a speed of 300 mm / min, and then in 70 ° C. After storing in 1 hour, the adhesive strength is measured in the same manner.

Further, the adhesive sheet of the present invention may have a structure in which the resin composition is laminated on both sides of the base material, and the base material has a thickness of 1/2 or less of the total thickness of the adhesive sheet. It is preferable to use it. This is preferable because the handleability of the adhesive sheet is improved, the adhesive layer does not protrude when the adhesive sheet is cut, and the adhesive sheet has excellent dimensional stability. As the substrate, any film or mesh material such as polyethylene terephthalate, polybutylene terephthalate, polyimide, polyphenylene sulfide, polyphenylene ether, polypropylene, polyethylene, polystyrene, etc. can be used, and the thickness is 1 to 30 μm. It is preferable to use the one having a thickness of 2 μm to 15 μm, and it is more preferable to use the one having a thickness of 2 μm to 15 μm.

In the configuration in which the resin composition is laminated on both sides of the base material, for example, the resin composition is directly applied to both sides of the base material to dry the solvent, or is applied to the surface of the release liner to dry the solvent. After that, it can be manufactured by pressure-bonding it to both surfaces of the base material.

(Applied body)
As the first adherend to which the adhesive sheet of the present invention is bonded, an arbitrary resin sheet or metal sheet or other bonding member that is opaque to active energy rays, particularly a laminating material, can be used.

Examples of the material of the resin sheet include polycarbonate, polymethylmethacrylate, alloy of polycarbonate and acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutylene terephthalate, polyimide, polyphenylene sulfide, polyphenylene ether, polypropylene, polyethylene, polystyrene and the like. Any material can be used. It is preferable to use polycarbonate or polymethylmethacrylate, which are excellent in stretchability, transparency and gloss by heating. Further, an arbitrarily colored resin sheet may be used, and when ultraviolet rays are used as active energy rays, even if ultraviolet rays are irradiated from the front surface of the resin sheet, ultraviolet rays to the adhesive layer of the adhesive sheet on the back surface are emitted. The amount of irradiation reached is small, and the adhesive sheet of the present invention can be preferably used, which is preferable.

When the molded product to which the resin sheet is attached is used outdoors, it is preferable to use a resin sheet in which an ultraviolet blocking agent is kneaded or a UV blocking layer is laminated. In the case of the resin sheet, when ultraviolet rays are used as active energy rays, even if ultraviolet rays are irradiated from the front surface of the resin sheet, the amount of ultraviolet rays reaching the adhesive layer of the adhesive sheet on the back surface is small, and the present invention It is preferable because the adhesive sheet can be preferably used.

As the material of the metal sheet, any material such as a sheet made of aluminum, copper, stainless steel, nickel, titanium, gold, silver, etc., or a resin sheet on which these metals are vapor-deposited or plated is used. be able to.

The thickness of the first adherend is preferably 0.05 to 2 mm, and the thickness is 0 for the purpose of adhering to the surface of the molded product which is the second adherend to prevent scratches. It is more preferable to use a sheet of 1 to 0.5 mm.

It is preferable that an arbitrary hard coat layer, mat layer, or the like is directly applied to the surface of the first adherend, or laminated on the surface by a co-extrusion method or the like.

Any colored decorative printing layer may be provided on the front surface or the back surface of the first adherend, either entirely or partially.

As the second adherend to which the adhesive sheet of the present invention is attached, a molded product in which any activation energy ray is opaque can be used.

The material of the second adherend includes polycarbonate, polymethylmethacrylate, alloy of polycarbonate and acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutylene terephthalate, polyimide, polyphenylene sulphide, polyphenylene ether, polypropylene, polyethylene. , Polystyrene, etc., or materials bonded to metal can be used, and due to the ease of moldability, polycarbonate, polymethylmethacrylate, polycarbonate and alloy of acrylonitrile-butadiene-styrene copolymer, etc. can be used. It is preferable to use it. Further, an arbitrarily colored adherend may be used, and when ultraviolet rays are used as active energy rays, even if ultraviolet rays are irradiated from the front surface side of the second adherend, the adhesive on the back surface adhesive sheet is used. It is preferable because the amount of ultraviolet rays reaching the layer is small and the adhesive sheet of the present invention can be preferably used.

The front surface and the back surface of the second adherend may be subjected to metal vapor deposition such as aluminum or chromium or colored printing with printing ink.

As the second adherend, a molded product manufactured by any molding method such as injection molding, extrusion molding, blow molding, vacuum forming, pressure molding, compression molding and the like can be used.

The method for producing the molded product is a step of adhering the adhesive layer of the adhesive sheet of the present invention and the first adherend by pressure-sensitive adhesion without heating [1], and the adhesive layer of the adhesive sheet. In the step of irradiating the other surface of the above with active energy rays to start polymerization [2], the laminate of the adhesive sheet is attached to the molding machine, and the laminate is kept heated while the surface of the first adherend is heated. In the step of pressurizing and attaching the second adherend to the surface of the adhesive layer [3], the laminate in which the first adherend and the second adherend are bonded with the adhesive sheet is post-cured. It is a manufacturing method including the steps [4] in order. As the second adherend, two or more kinds of adherends may be bonded at the same time in the step [3].
The step [1] is preferably carried out in an environment of 0 ° C. to 50 ° C., and the adhesive sheet of the present invention is carried out in an environment of 10 ° C. to 40 ° C. based on the fact that the adhesive sheet of the present invention can be bonded without heating. Is more preferable.
In the step [3], it is preferable that the second adherend is pressed against the surface of the adhesive layer of the laminate, and the first adherend is stretched and attached.

As a specific example of the adhesive sheet bonding method of the present invention, a release liner on one side is removed from the adhesive sheet, and the adhesive sheet is bonded to the first adherend in a room temperature atmosphere, and then cut to an arbitrary size. The second adherend is passed through the release liner to the surface of the adhesive layer in a state where the other release liner is removed and the adhesive layer is exposed, or in a state where the release liner is attached. After being irradiated with active energy rays, it is attached to a device for bonding (for example, an injection in-mall molding machine, a vacuum forming machine, a pressure molding machine, etc.). Then, within about 20 to 60 minutes after the irradiation with the active energy rays, the adhesive sheet of the present invention together with the first adherend is heated to about 100 to 160 ° C. in a room temperature atmosphere or by a far infrared heater or the like. While doing so, it is bonded to the surface of the second adherend with a pressing force of about 0.1 to 0.2 MPa. After bonding, the excess adhesive sheet and the first adherend are cut off and left for about 1 hour in an environmental atmosphere of about 70 ° C. for post-curing to produce a molded product.

Light rays such as ultraviolet rays, infrared rays, and electron beams are used as the active energy rays, and when a photocation initiator is used as the polymerization initiator, it is a simple device to use the active energy rays by ultraviolet rays. Irradiation is possible and is preferable. Any irradiation device can be used for ultraviolet irradiation, and ultraviolet lamps such as high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, ultraviolet LED lamps, and ultraviolet electrodeless lamps can be used. The irradiation condition of ultraviolet rays is preferably 100 to 500 mW / cm ² m, and the integrated irradiation amount is preferably 100 to 1,000 mJ / cm ² . Under the irradiation conditions, the tensile storage elastic modulus of the adhesive layer after irradiation with active energy rays can be easily adjusted to the above range, the curing reaction does not proceed immediately after irradiation, and the adhesive layer is bonded to the second adherend. Pressure-sensitive adhesiveness can be maintained until the process.

Before the adhesive sheet of the present invention activated by light rays or the like is irradiated with the activation energy ray, the curing reaction does not easily proceed in a room temperature atmosphere, the storage stability is good, and after the activation energy ray irradiation. The curing reaction does not proceed rapidly, it can be attached to the second adherend, and it can be post-cured by heating at 100 ° C. or lower. Further, the active energy rays may be used alone or in combination of two or more.

In the moist heat environment, the manufactured molded product is left unattended for the purpose of evaluating the reliability of the molded part in which the first adherend and the second adherend are bonded with the adhesive sheet of the present invention. To. Examples of the moist heat environment include 60 ° C. and 90% RH and 85 ° C. and 85% RH, and the environment is left for a period of about 2 to 72 hours, and the presence or absence of swelling or floating is observed.

The molded product in which the bonding member, which is the first adherend, and the second adherend are bonded by the adhesive sheet of the present invention, can be used for the exterior of home appliances, the exterior of mobile terminals, the interior and exterior of automobiles, and the like. It is suitably used for the resin molded product used. It is a part molded in three dimensions by injection molding, extrusion molding, etc., and a bonding member having a hard coat layer or a mat layer on the surface to prevent scratches is bonded to the surface of these molded products with the adhesive sheet of the present invention. The occurrence of swelling and floating due to outgas and residual stress of the bonding member during heating and bonding is suppressed, and the generation of swelling and floating is suppressed even when left in a moist heat environment, and the appearance quality is excellent. It is a molded product.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

<Preparation of acrylic copolymer (A)>
86.3 parts by mass of ethyl acrylate, 11 parts by mass of N-isopropylacrylamide, 2 parts by mass of acrylonitrile, 0.7 parts by mass of glycidyl methacrylate in a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet. A portion and 0.2 parts by mass of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 455 parts by mass of methyl ethyl ketone, polymerized at 80 ° C. for 8 hours after substitution with nitrogen, and the solid content was 18% by mass. An acrylic copolymer (A) having a weight average molecular weight of 350,000 was obtained. The epoxy equivalent is 14,200 g / eq. The glass transition temperature was 11 ° C.

<Preparation of acrylic copolymer (B)>
In a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet, 52 parts by mass of ethyl acrylate, 24.7 parts by mass of n-butyl acrylate, 19 parts by mass of methyl methacrylate, and 2 parts by mass of acrylonitrile. 2.3 parts by mass of glycidyl methacrylate and 0.2 parts by mass of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 567 parts by mass of methyl ethyl ketone, and after nitrogen substitution, the polymer was polymerized at 80 ° C. for 8 hours. An acrylic copolymer (B) having a solid content of 15% by mass and a weight average molecular weight of 850,000 was obtained. The epoxy equivalent is 4,760 g / eq. The glass transition temperature was 12 ° C.

<Preparation of acrylic copolymer (C)>
56 parts by mass of n-butyl acrylate, 20 parts by mass of cyclohexyl acrylate, 10 parts by mass of methyl acrylate, 4 parts by mass of diacetone acrylamide in a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet. 10 parts by mass of glycidyl methacrylate and 0.2 parts by mass of 2,2'-azobisisobutylnitrile as a polymerization initiator are dissolved in 300 parts by mass of methyl ethyl ketone, and after nitrogen substitution, the polymer is polymerized at 80 ° C. for 8 hours to obtain a solid content. An acrylic copolymer (C) having a mass average of 25,000% by mass and a mass average molecular weight of 500,000 was obtained. The epoxy equivalent is 1,320 g / eq. The glass transition temperature was -11 ° C.

<Preparation of acrylic copolymer (D)>
56 parts by mass of n-butyl acrylate, 20 parts by mass of cyclohexyl acrylate, 10 parts by mass of methyl acrylate, 12 parts by mass of diacetone acrylamide, in a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet. 2 parts by mass of hydroxyethyl acrylate and 0.2 parts by mass of 2,2'-azobisisobutylnitrile as a polymerization initiator were dissolved in 70 parts by mass of methyl ethyl ketone and 47 parts by mass of ethyl acetate, and after nitrogen substitution, at 80 ° C. After 8 hours of polymerization, an acrylic copolymer (D) having a solid content of 46% by mass and a weight average molecular weight of 750,000 was obtained. The epoxy equivalent is 0 g / eq, and the hydroxyl group equivalent is 6,670 g / eq. The glass transition temperature was -14 ° C.

(Example 1)
As the polymerizable resin, 555 parts by mass of the solution of the acrylic copolymer (A) and CEL-2021P (manufactured by Daicel Co., Ltd., bifunctional alicyclic epoxy resin, epoxy equivalent 131 g / eq., B in an environment of 25 ° C. Mold viscosity 245 mPa · s) 30 parts by mass and 8 parts by mass of CPI-100P (manufactured by San-Apro Co., Ltd., sulfonium salt-based, solid content 50% by mass) as a polymerization initiator are mixed to obtain a resin composition (a-1). rice field. The total epoxy equivalent of the resin composition (a-1) is 9,980 g / eq. Met.

Next, the resin composition (a-1) was applied to the surface of a release liner (one side of a polyethylene terephthalate film having a thickness of 75 μm peeled with a silicone compound) using a columnar metal applicator. The coating was applied so that the thickness after drying was 50 μm.
Further, the coated material was put into a dryer at 50 ° C. for 3 minutes and then put into a dryer at 75 ° C. for 5 minutes to dry, to obtain an adhesive sheet having a thickness of 50 μm.
Adhesion obtained by coating the surface of another release liner (one side of a polyethylene terephthalate film with a thickness of 38 μm peeled with a silicone compound) so that the thickness after drying becomes 50 μm in the same manner as described above. The sheet was bonded to the adhesive sheet to obtain an adhesive sheet (A-1) having a thickness of 100 μm.

(Example 2)
The amount of the acrylic copolymer (A) used as the polymerizable resin was 333 parts by mass, and the amount of CEL-2021P used was 40 parts by mass to obtain the resin composition (a-2), and two adhesive sheets. Same as Example 1 except that another release liner (one side of a polyethylene terephthalate film having a thickness of 38 μm is peeled off with a silicone compound) is attached to the surface of one adhesive sheet without bonding. Then, an adhesive sheet (A-2) having a thickness of 50 μm was obtained. The total epoxy equivalent of the resin composition (a-2) is 8,570 g / eq. Met.

(Example 3)
Except that the amount of the acrylic copolymer (A) used as the polymerizable resin was 444 parts by mass and the amount of CEL-2021P used was 20 parts by mass to obtain the resin composition (a-3), the same as in Example 1. Similarly, an adhesive sheet (A-3) having a thickness of 100 μm was obtained. The total epoxy equivalent of the resin composition (a-3) is 11,390 g / eq. Met.

(Example 4)
As the polymerizable resin, Denacol EX321L (manufactured by Nagase ChemteX Corporation, trimethylolpropane triglycidyl ether, epoxy equivalent 130 g / eq., B-type viscosity 300 mPa · s in a 25 ° C environment) is used instead of CEL-2021P. An adhesive sheet (A-4) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the resin composition (a-4) was used. The total epoxy equivalent of the resin composition (a-4) is 9,980 g / eq. Met.

(Example 5)
The same as in Example 1 except that 467 parts by mass of the solution of the acrylic copolymer (B) and 30 parts by mass of CEL-2021P were used as the polymerizable resin to prepare the resin composition (b-1). , An adhesive sheet (B-1) having a thickness of 100 μm was obtained. The total epoxy equivalent of the resin composition (b-1) is 3,370 g / eq. Met.

(Example 6)
As the polymerizable resin, only 400 parts by mass of the solution of the acrylic copolymer (C) was used to prepare the resin composition (c-1), and two adhesive sheets were not bonded, and one adhesive sheet was used. An adhesive sheet having a thickness of 50 μm (similar to Example 1) except that another release liner (one side of a polyethylene terephthalate film having a thickness of 38 μm was peeled off with a silicone compound) was attached to the surface of the film. C-1) was obtained. The total epoxy equivalent of the resin composition (c-1) is 2,210 g / eq. Met.

(Comparative Example 1)
Example 1 except that the amount of the acrylic copolymer (A) used was 500 parts by mass and the amount of CEL-2021P used was 10 parts by mass as the polymerizable resin to prepare the resin composition (a-5). In the same manner as above, an adhesive sheet (A-5) having a thickness of 100 μm was obtained. The total epoxy equivalent of the resin composition (a-5) is 12,800 g / eq. Met.

(Comparative Example 2)
An adhesive sheet having a thickness of 100 μm was used in the same manner as in Example 1 except that 152 parts by mass of the solution of the acrylic copolymer (D) was used as the polymerizable resin to prepare the resin composition (d-1). D-1) was obtained. The total epoxy equivalent of the resin composition (d-1) is 9,940 g / eq. Met.

(Comparative Example 3)
To 100 parts by mass of the solution of the acrylic copolymer (D), 0.8 parts by mass of Takenate D110N (manufactured by Mitsui Chemicals, Inc., trimethylolpropane modified product of xylylene diisocyanate, solid content 75% by mass) as an isocyanate cross-linking agent. A resin composition (d-2) was obtained, which was only added and did not use a polymerization initiator. An adhesive sheet having a thickness of 100 μm was prepared in the same manner as in Example 1, and left at 23 ° C. for 7 days to obtain an adhesive sheet (D-2). The total epoxy equivalent of the resin composition (d-2) is 0 g / eq. Met.

(Comparative Example 4)
Only Finetack RX-301 (manufactured by DIC Corporation, ultraviolet curable pressure-sensitive adhesive, solid content 60% by mass) was used as the polymerizable resin to prepare the resin composition (e-1), and the polymerization initiator was used. An adhesive sheet (E-1) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that no additional addition was made. The total epoxy equivalent of the resin composition (e-1) is 0 g / eq. Met.

(Comparative Example 5)
As the polymerizable resin, 250 parts by mass of jER1256B40 (manufactured by Mitsubishi Chemical Corporation, phenoxy resin, epoxy equivalent 8,000 g / eq.) Was used instead of the acrylic copolymer (A), and a resin composition (f-1) was used. ) Was obtained in the same manner as in Example 1 to obtain an adhesive sheet (F-1) having a thickness of 100 μm. The total epoxy equivalent of the resin composition (f-1) is 5,640 g / eq. Met.

The resin compositions of Examples 1 to 5, Comparative Examples 1 and 2, and Comparative Example 5 have a photopolymerization initiator, and are acrylic copolymers (A) to (C) and an epoxy resin. Has an epoxy group as a reaction site, and the acrylic copolymer (D) has a hydroxyl group as a reaction site, and since an epoxy resin is used in combination as a polymerizable resin, the epoxy group can be obtained by irradiating with light. It can be activated and allowed to undergo a curing reaction. On the other hand, the adhesive sheet of Comparative Example 3 does not have a reaction site and does not contain a photopolymerization initiator, so that it does not undergo a curing reaction by active energy rays and post-curing. Further, the adhesive sheet of Comparative Example 4 has a radically reactive polymerizable resin and a photopolymerization initiator, and can be cured by the photopolymerization initiator, but the curing reaction is carried out immediately after irradiation with light. This is an adhesive sheet that is extremely difficult to attach to the second adherend.

(Tension storage elastic modulus E'and glass transition temperature)
The release liner was removed from the adhesive sheets obtained in the above Examples and Comparative Examples, and the adhesive sheets were bonded to each other to prepare a sample having a thickness of 200 μm. Using a tensile dynamic viscoelasticity measuring device (TA Instrument Co., Ltd., RSA III), the temperature rise rate is 3 ° C / min, the measurement frequency is 1.0 Hz, and the measurement temperature range is -40 to 150 ° C. , The tensile storage elastic modulus (E') at 25 ° C. of the adhesive layer before irradiation with active energy rays was calculated. In addition, the loss tangent was calculated, and the peak temperature of the loss tangent was taken as the glass transition temperature. The glass transition temperature of the acrylic copolymers (A) to (D) was the same as in Example 1 except that only the acrylic copolymer was used, and the glass was prepared in the same manner as the adhesive sheet. The transition temperature was measured.

Further, the release liner was removed from one of the adhesive sheets obtained in the above Examples and Comparative Examples, and an ultraviolet electrodeless lamp (fusion lamp H valve) was used on the surface of the exposed adhesive layer to emit ultraviolet rays at 500 mJ / cm ² . The tensile storage elasticity (E') of the adhesive layer after irradiation with active energy rays at 25 ° C. is the same as described above, except that the adhesive sheet obtained by irradiation is cut into 5 mm × 50 mm. ) Was calculated. The adhesive sheet obtained in Comparative Example 4 was irradiated with the ultraviolet rays without removing the release liner.

Further, the test pieces obtained by irradiating the adhesive sheets obtained in the Examples and Comparative Examples with ultraviolet rays were further left at 70 ° C. for 1 hour, and the cured product was cut into 5 mm × 50 mm. The tensile storage elastic modulus (E') and the glass transition temperature of the cured adhesive layer at 100 ° C. and 25 ° C. were calculated in the same manner as described above, except that the adhesive layer was used.

(Swelling resistance and floating resistance)
After cutting the adhesive sheets obtained in the above Examples and Comparative Examples to a size of 60 mm × 60 mm, one of the release liners was removed, and the thickness was 0.2 mm at a pressure of 0.2 MPa at a speed of 1 m / min. A test piece was prepared by laminating a polycarbonate sheet (Polycarbonate Ace ECG-101 manufactured by Sumitomo Bakelite Co., Ltd.).

Next, 20 test pieces obtained by removing the remaining one peeling liner and irradiating the exposed surface of the adhesive layer with ultraviolet rays at 500 mJ / cm ² using an ultraviolet electrodeless electrode lamp (fusion lamp H bulb). After a lapse of minutes, it was temporarily fixed to a 1.5 mm thick polycarbonate plate (Iupilon NF-200VUNS2 manufactured by Mitsubishi Gas Chemical Company, Inc.). The adhesive sheet obtained in Comparative Example 4 was irradiated with the ultraviolet rays without removing the release liner.

Immediately after the temporary fixing, heat pasting was performed for 2 minutes at a pressure of 130 ° C. and 0.1 MPa using a hot press device. As the heat press device, a heat press machine "TP-750 Air Press" manufactured by Tester Sangyo Co., Ltd. was used. The surface of the obtained test piece was visually observed from the side of a polycarbonate sheet having a thickness of 0.2 mm and evaluated based on the following criteria.
◯: No swelling or floating was observed.
Δ: Occurrence of swelling or floating was observed in a part.
X: Occurrence of swelling or floating was observed over the entire surface.

Further, each test piece obtained above was left at 70 ° C. for 1 hour and then cured, and then left at 85 ° C. and 85% RH for 24 hours as a moist heat condition, and the surface of the obtained test piece was left. Was observed from the first adherend surface side and evaluated based on the same criteria as described above.

(Gel fraction)
The adhesive sheets obtained in the above Examples and Comparative Examples were cut into a size of 40 mm × 50 mm, and then only the release liner on one side was removed to obtain a test piece. After measuring the mass of the test piece, it was immersed in toluene adjusted to 23 ° C. for 24 hours.
After the immersion, the test piece was taken out and dried in a dryer at 105 ° C. for 1 hour, and the mass was measured. Based on the above mass and the following formula, the gel fraction of the adhesive layer before irradiation with active energy rays was calculated.

Gel fraction (mass%) of adhesive layer before irradiation with active energy rays = {(mass of adhesive layer of adhesive sheet remaining without being dissolved in toluene) / (adhesive layer of adhesive sheet before immersion in toluene) Mass)} x 100

The mass of the adhesive layer of the adhesive sheet before immersion refers to a value obtained by subtracting the mass of the release liner used for manufacturing the test piece from the mass of the test piece. Further, the mass of the remaining adhesive layer refers to a value obtained by subtracting the mass of the release liner from the mass of the residue after drying.

The release liner is removed from one of the adhesive sheets obtained in the above Examples and Comparative Examples, and the surface of the exposed adhesive layer is irradiated with ultraviolet rays at 500 mJ / cm ² using an ultraviolet non-electrode lamp (fusion lamp H valve). The resulting adhesive sheet was left at 70 ° C. for 1 hour and then cured, and then the cured adhesive layer was evaluated in the same manner as in the evaluation of the gel fraction of the adhesive layer before irradiation with active energy rays. The gel fraction was measured. The adhesive sheet obtained in Comparative Example 4 was irradiated with the ultraviolet rays without removing the release liner.

(Total light transmittance Tt and haze)
For the total light transmittance Tt and haze, two polycarbonate sheets having a thickness of 0.2 mm, a total light transmittance Tt of 90% and a haze of 0.2% were prepared, and the examples and comparisons were made. A test obtained by removing the peeling liner on one side from the adhesive sheet obtained in the example and irradiating the exposed surface of the adhesive layer with ultraviolet light at 500 mJ / cm ² using an ultraviolet non-electrode lamp (fusion lamp H valve). The pieces are bonded between the two polycarbonate sheets so that air bubbles do not enter, and after a post-curing step at 70 ° C. for 1 hour, all light rays are subjected to an arbitrary total light transmittance meter according to JIS K7136. Transmittance Tt and haze were measured.

(Peel adhesive strength before irradiation with active energy rays)
The adhesive sheets obtained in the above Examples and Comparative Examples were cut into a width of 20 mm and a length of 100 mm, a release liner on one side was removed, and then a polyester film having a thickness of 50 μm (manufactured by Unitika Ltd., S-50) was formed. The test pieces were prepared by laminating them. Each test piece was attached to a 1.5 mm thick polycarbonate plate (Iupilon NF-200VUNS2 manufactured by Mitsubishi Gas Chemical Company, Inc.) under a 23 ° C. and 50% RH environment, and reciprocated once at a speed of 300 mm / min with a 2 kg roller. After the pressurization was performed, the adhesive strength when the polyester film was peeled off at a pulling speed of 50 mm / min in the 180 ° direction was measured within 1 minute. Since the adhesive sheet of Comparative Example 3 is an adhesive sheet that does not undergo a curing reaction due to active energy rays and post-heating, only the peel adhesive strength of the adhesive sheet before irradiation with the active energy rays and the peel adhesive strength after being left in a moist heat are used. evaluated.

(Peel adhesive strength after irradiation with active energy rays)
In the same manner as described above, a test piece is prepared by laminating it on a polyester film having a thickness of 50 μm, the peeling liner on the remaining one side is removed, and an ultraviolet electrodeless electrode lamp (fusion lamp H valve) is used on the surface of the exposed adhesive layer. The adhesive strength was measured in the same manner as described above, except that the test piece left for 20 minutes after irradiation with ultraviolet rays at 500 mJ / cm ² was used. The adhesive sheet obtained in Comparative Example 4 was irradiated with the ultraviolet rays without removing the release liner.

(Peel adhesive strength after curing reaction)
Similarly, a test piece left for 20 minutes after irradiation with ultraviolet rays was prepared and temporarily fixed to the 1.5 mm-thick polycarbonate plate. Immediately after the temporary fixing, heat pasting was performed for 2 minutes at a pressure of 130 ° C. and 0.1 MPa using a hot press device. As the heat press device, a heat press machine "TP-750 air press" manufactured by Tester Sangyo Co., Ltd. was used. The obtained test piece was left at 70 ° C. for 1 hour and then cured, and the peel adhesive strength was measured in the same manner as described above.

(Peel adhesive strength after leaving in moist heat)
The test piece cured in the same manner as described above was left in 85 ° C. and 85% RH for 24 hours, taken out in 23 ° C. and 50% RH, and 1 hour later, the peel adhesive strength was measured in the same manner as described above.

(Storage stability)
The adhesive sheets obtained in Examples and Comparative Examples were left at 40 ° C. for 30 days, and then the gel fraction was measured in the same manner as described above and evaluated based on the following criteria.
◯: The change in gel fraction was less than 10%.
X: The change in gel fraction was 10% by mass or more.

Claims (12)

An adhesive sheet provided with an adhesive layer, which is used for bonding two or more adherends having a surface through which active energy rays do not pass.
The acrylic co-weight obtained by polymerizing a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms and a vinyl monomer having an epoxy group and / or an oxetanyl group in the adhesive layer. Consists of a resin composition containing coalesced
The tensile storage elasticity of the adhesive layer at 25 ° C. before irradiating the surface of the adhesive layer with active energy rays is 1 × 10 ³ to 1 × 10 ⁶ Pa, and ultraviolet rays as active energy rays are applied to the surface of the adhesive layer. The tensile storage elasticity of the adhesive layer at 25 ° C. after irradiation is 1 × 10 ³ to 1 × 10 ⁶ Pa, which is larger than the tensile storage elasticity before irradiation with the active energy rays. An adhesive sheet having a tensile storage elasticity of 2 × 10 ⁴ Pa or more at 100 ° C. after the curing reaction. The adhesive sheet according to claim 1, which contains at least one type of polymerizable resin. The adhesive sheet according to claim 1 or 2, wherein the polymerizable resin has a weight average molecular weight of 10,000 to 1,000,000. The adhesive sheet according to any one of claims 1 to 3, wherein the polymerizable resin has a glass transition temperature of −30 to 50 ° C. The adhesive sheet according to any one of claims 1 to 4, wherein the polymerizable resin contains an epoxy group and / or an oxetanyl group. The adhesive sheet according to any one of claims 1 to 5, wherein the polymerizable resin contains a group having a nitrogen atom. The adhesive sheet according to any one of claims 1 to 6, wherein the polymerizable resin is an acrylic copolymer. The adhesive sheet according to any one of claims 1 to 7, which contains at least two or more kinds of polymerizable resins. The total epoxy equivalent of the polymerizable resin is 500 to 20,000 g / eq. The adhesive sheet according to any one of claims 1 to 8. A molded product to which the adhesive sheet according to any one of claims 1 to 9 is attached. The molded product according to claim 10, wherein the material is made of resin. A method for manufacturing a molded product in which a first adherend and a second adherend having a surface through which active energy rays do not pass are bonded together using an adhesive sheet provided with an adhesive layer.
The acrylic co-weight obtained by polymerizing a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms and a vinyl monomer having an epoxy group and / or an oxetanyl group in the adhesive layer. It is composed of a resin composition containing a coalescence, and the tensile storage elasticity of the adhesive layer at 25 ° C. before irradiating the surface of the adhesive layer with active energy rays is 1 × 10 ³ to 1 × 10 ⁶ Pa.
The step of adhering the adhesive layer of the adhesive sheet and the first adherend by pressure-sensitive adhesion without heating [1], as active energy rays to the other surface of the adhesive layer of the adhesive sheet. Step of irradiating with ultraviolet rays to start polymerization [2], when the tensile storage elasticity of the adhesive layer at 25 ° C. is larger than that before irradiation and is 1 × 10 ³ to 1 × 10 ⁶ Pa. In the step of pressurizing and attaching the second adherend to the surface of the adhesive layer [3], the laminate in which the first adherend and the second adherend are bonded with the adhesive sheet. A method for producing a molded product, which comprises the step of post-curing [4].