TW202330842A - Photocurable Adhesive Sheet - Google Patents

Abstract

An adhesive sheet (S) according to the present invention is a photocurable adhesive sheet that includes a base polymer serving as a photopolymer. After a photocurable adhesive sheet (S) is bonded to an alkali glass sheet manufactured according to a float process, a heating and pressurization process is performed under subsequent prescribed conditions, and a photocuring process is performed under a subsequent condition of an irradiated integrated light quantity of 3,000 mJ/cm2, the photocurable adhesive sheet (S) has a peel strength of 1.5 N/10 mm or above in a peel test in which the photocurable adhesive sheet (S) is peeled from the alkali glass sheet under prescribed conditions.

Description

Photocurable Adhesive Sheet

The present invention relates to a photocurable adhesive sheet.

The display panel has, for example, a laminated structure including elements such as a pixel panel, a polarizing plate, and a cover glass. In the manufacturing process of the display panel, in order to join the elements included in the laminated structure, for example, a transparent adhesive sheet (optical adhesive sheet) is used. About the adhesive sheet for a display panel use, it describes, for example in the following patent document 1. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2012-62345

[Problem to be solved by the invention]

The optical adhesive sheet of patent document 1 is manufactured as follows. First, after preparing a reaction solution including monomer components for forming an acrylic base polymer, a thermal polymerization initiator, and a solvent, an acrylic base polymer is formed by solution polymerization in the reaction solution. Next, a solvent is added to the reaction solution to prepare a polymer solution with an adjusted polymer concentration. Secondly, an adhesive composition (a solvent-based adhesive composition) is prepared by adding a thermal crosslinking agent and a crosslinking auxiliary agent into the polymer solution. Next, the adhesive composition is coated on the substrate to form a coating film. Next, the coating film on the substrate is dried by heating to form an adhesive layer (drying step). Secondly, through the aging treatment, the cross-linking reaction of the base polymer caused by the thermal cross-linking agent is carried out in the adhesive layer. In the above manner, an optical adhesive sheet is formed on the substrate. Thus, Patent Document 1 describes an optical adhesive sheet formed from a solvent-based adhesive composition.

However, in the above-mentioned drying step, a relatively large amount of solvent in the coating film will evaporate to the outside of the coating film. An adhesive sheet whose manufacturing process includes such a step is not preferable from the viewpoint of reducing the environment.

On the other hand, elements with high surface smoothness such as glass substrates and cover glass are included in the laminated structure of the display panel. Therefore, high adhesiveness is required for the adhesive sheet used for manufacturing a display panel (adhesive sheet for a display panel).

Also, elements having surface steps are included in the laminated structure of the display panel. For example, a decorative or light-shielding printing layer is provided on the edge of the side surface of the pixel panel of the cover glass, and there is a step difference between the surface of the cover glass and the surface of the printing layer (printing step difference). Therefore, flexibility (step followability) to the extent that it can follow printing steps is also required for the adhesive sheet used for a display panel. Insufficient step followability of the adhesive sheet, for example, causes air bubbles to form between the adhesive sheet bonded to the surface of the pixel panel with the printed layer of the cover glass and the cover glass along the printed layer, which is not preferable.

The present invention provides a light-curable adhesive sheet suitable for reducing environmental load and suitable for use in display panels. [Technical means to solve the problem]

The present invention [1] includes a photocurable adhesive sheet that includes a base polymer as a photopolymer and has photocurability, and is formed by laminating the above photocurable adhesive sheet on a surface produced by a float method. The soda glass plate, then heat and pressurize the above-mentioned photocurable adhesive sheet on the above-mentioned soda glass plate under the conditions of 50°C, 0.5 MPa and 15 minutes, and then irradiate the cumulative light amount of 3000 mJ/cm ² After photocuring the above-mentioned photocurable adhesive sheet under the conditions of 23°C, relative humidity of 50%, peeling angle of 180° and tensile speed of 300 mm/min, the above photocurable adhesive sheet was automatically In the peeling test of the above-mentioned soda glass plate peeling, it has a peeling strength of 1.5 N/10 mm or more.

The present invention [2] includes the photocurable adhesive sheet as described in the above [1], wherein the above photocurable adhesive sheet is subjected to photohardening treatment under the condition of irradiating a cumulative light amount of 3000 mJ/cm ² , and then The above-mentioned light-curable adhesive sheet was bonded to an alkali glass plate produced by the float method, and then the above-mentioned light-hardenable adhesive sheet on the above-mentioned alkali glass plate was bonded under the conditions of 50°C, 0.5 MPa and 15 minutes. After heat and pressure treatment, the above-mentioned photocurable adhesive sheet was peeled from the above-mentioned alkali glass plate under the conditions of 23°C, relative humidity of 50%, peeling angle of 180°, and tensile speed of 300 mm/min. It has a peel strength above 1.5 N/10 mm.

The present invention [3] includes a photocurable adhesive sheet that contains a base polymer as a photopolymer and has photocurability, and is irradiated with a cumulative light amount of 3000 mJ/cm ² to the above photocurable adhesive sheet. The material was subjected to photohardening treatment, and then the above-mentioned photocurable adhesive sheet was attached to the alkali glass plate produced by the float method, and then the above-mentioned alkali glass plate was subjected to the conditions of 50 ° C, 0.5 MPa and 15 minutes. After the above-mentioned light-curable adhesive sheet was subjected to heat and pressure treatment, the above-mentioned photo-hardenable adhesive sheet was removed from the above-mentioned In the peel test of peeling off the alkali glass plate, it has a peel strength of 1.5 N/10 mm or more.

The present invention [4] includes the photocurable adhesive sheet described in any one of the above [1] to [3], which has a light transmittance of 85% or more at a wavelength of 420 nm, and has a light transmittance of at least 85% at a wavelength of 380 nm. The light transmittance is below 15%.

The present invention [5] includes the photocurable adhesive sheet according to any one of the above [1] to [4], which has a haze of 1% or less.

The present invention [6] includes the photocurable adhesive sheet as described in any one of the above-mentioned [1] to [5], which has a shear storage modulus of elasticity at 25° C. of 0.2 MPa or less.

The present invention [7] includes the photocurable adhesive sheet described in any one of the above [1] to [6], which is hardened by irradiation with light with a cumulative light intensity of 3000 mJ/cm ² . It has a shear storage elastic modulus above 0.21 MPa at °C.

The present invention [8] includes the photocurable adhesive sheet described in any one of the above-mentioned [1] to [ ⁷ ], which has - Glass transition temperature below 3°C. [Effect of Invention]

In the photocurable adhesive sheet of the present invention, as described above, the base polymer is a photopolymer. Such an adhesive sheet is suitable for being manufactured from a solvent-free adhesive composition. Furthermore, the solvent-free adhesive composition does not require a drying step for volatilizing and removing the solvent from the coating film of the composition in the process of producing an adhesive sheet from the composition, and thus is suitable for reducing environmental load.

Moreover, the photocurable adhesive sheet of this invention has photocurability as mentioned above. With regard to such a photocurable adhesive sheet, it is possible to secure the flexibility of the adhesive sheet when bonding adherends using the adhesive sheet (before photocuring), and to photocure the sheet after bonding. (high elasticity). This kind of photocurable adhesive sheet is suitable for both the followability of the step difference on the surface of the adherends during the bonding between the adherends and the bonding reliability after the bonding between the adherends. Therefore, the photocurable adhesive sheet of this invention is suitable for manufacturing the display panel containing the element which has a surface level difference.

In addition, the photocurable adhesive sheet of the present invention has a peeling strength of 1.5 N/10 mm or more under specific conditions with respect to an alkali glass plate produced by a float method as described above. The soda glass plate produced by the float method is difficult to attach adhesives due to its high surface smoothness, but the photocurable adhesive sheet of the present invention has excellent adhesion to the glass plate. This photocurable adhesive sheet is suitable for bonding adherends with relatively high surface smoothness, such as glass substrates and cover glasses in display panels. Therefore, the photocurable adhesive sheet of this invention is suitable for a display panel use.

The adhesive sheet S which is one embodiment of the photocurable adhesive sheet of the present invention, as shown in FIG. 1 , has a sheet shape with a specific thickness and spreads in a direction (surface direction) perpendicular to the thickness direction. FIG. 1 exemplarily shows a state where release liners L1 and L2 are bonded to both surfaces of an adhesive sheet S. As shown in FIG. The release liner L1 is arranged on one surface of the thickness direction H of the adhesive sheet S. The release liner L2 is arrange|positioned on the other surface of the thickness direction H of the adhesive sheet S. Moreover, the adhesive sheet S is a transparent adhesive sheet (optical adhesive sheet) arrange|positioned at the light passing part of a display panel. As a display panel, a liquid crystal panel and an organic electroluminescence panel are mentioned, for example. The display panel has, for example, a laminated structure including elements such as a pixel panel, a film-shaped polarizing plate (polarizing film), a touch panel, and a cover glass. The adhesive sheet S is used, for example, to join the elements included in the laminated structure in the manufacturing process of the display panel.

Adhesive sheet S is a sheet-like pressure-sensitive adhesive. The adhesive sheet S contains a base polymer as a photopolymer, and in this embodiment, further contains a photopolymerizable polyfunctional compound and a photopolymerization initiator, and has photocurability. In addition, in the present embodiment, the peel strength of the adhesive sheet S in at least one test selected from the following first test and the following second test is 1.5 N/10 mm or more.

In the first test, the adhesive sheet S was attached to the alkali glass plate produced by the float method, and then the adhesive sheet S on the alkali glass plate was subjected to the conditions of 50°C, 0.5 MPa and 15 minutes. After heat and pressure treatment, the adhesive sheet S was subjected to photohardening treatment under the condition of irradiating a cumulative light intensity of 3000 mJ/cm ² , and then carried out at 23°C, relative humidity of 50%, peeling angle of 180° and tensile speed of 300°C. Peeling test of peeling the adhesive sheet S from the alkali glass plate under the condition of mm/min to measure the peeling strength (peeling strength F1). The first test is more specifically as described below in relation to the examples.

Peel strength F1 refers to the peel strength of the adhesive sheet S attached to the alkali glass plate before light hardening after light hardening on the alkali glass plate. Such a peel strength F1 is preferably at least 2 N/10 mm, more preferably at least 2.5 N/10 mm, still more preferably at least 4 N/10 mm, still more preferably at least 5 N/10 mm, and still more preferably It is more than 6.1 N/10 mm, preferably more than 6.3 N/10 mm, most preferably more than 6.5 N/10 mm. Peel strength F1 is substantially 30 N/10 mm or less. As a method of adjusting the peel strength F1, selection of the kind of base polymer in the adhesive sheet S, adjustment of molecular weight, and adjustment of a compounding quantity are mentioned, for example. Selection of the type of base polymer includes adjustment of the composition of monomers forming the base polymer. As the adjustment method of peel strength F1, selection of the kind of the component other than a base polymer in the adhesive sheet S, and adjustment of the compounding quantity of the said component are also mentioned. As this component, a photopolymerizable polyfunctional compound, a photoinitiator, a silane coupling agent, and an oligomer are mentioned. The above peel strength adjustment method is also the same with regard to the following peel strength F2.

In the second test, the adhesive sheet S was subjected to photohardening treatment under the condition of irradiating a cumulative light intensity of 3000 mJ/cm ² , and then the adhesive sheet S was attached to an alkali glass plate produced by the float method. After that, heat and pressurize the adhesive sheet S on the alkali glass plate under the conditions of 50°C, 0.5 MPa and 15 minutes, then implement it at 23°C, relative humidity 50%, peeling angle 180° and tensile speed 300 mm Peeling test of peeling the adhesive sheet S from the alkali glass plate under the condition of 1/min to measure the peeling strength (peeling strength F2). The second test is more specifically as described below in relation to the examples.

The peel strength F2 is the peel strength of the adhesive sheet S attached to the alkali glass plate after photohardening. Such a peel strength F2 is preferably at least 2 N/10 mm, more preferably at least 2.5 N/10 mm, further preferably at least 4 N/10 mm, still more preferably at least 5 N/10 mm, and still more preferably It is more than 6.1 N/10 mm, preferably more than 6.3 N/10 mm, most preferably more than 6.5 N/10 mm. Peel strength F2 is substantially 30 N/10 mm or less.

The adhesive sheet S is as described above, and the base polymer is a photopolymer. Such an adhesive sheet S is suitable for being manufactured from a solvent-free adhesive composition. Furthermore, the solvent-free adhesive composition does not require a drying step for volatilizing and removing the solvent from the coating film of the composition in the process of producing the adhesive sheet S from the composition, and thus is suitable for reducing environmental load.

Moreover, the adhesive sheet S has photocurability as mentioned above. Regarding the photocurable adhesive sheet S, the flexibility of the adhesive sheet S can be ensured when bonding the adherends with the adhesive sheet S (before photocuring), and the adhesive sheet S can be photocured after joining. (high elasticity). This kind of adhesive sheet S is suitable for both the followability of the step difference on the surface of the adherends during the bonding between the adherends and the bonding reliability after the bonding between the adherends. Therefore, the adhesive sheet S is suitable for manufacturing a display panel including elements having surface steps.

In addition, the adhesive sheet S has a peeling strength of 1.5 N/10 mm or more with respect to the soda glass plate produced by the float method in the above-mentioned first test and/or the above-mentioned second test. The soda glass plate produced by the float method is difficult to attach adhesives due to its high surface smoothness, but the adhesive sheet S has excellent adhesion to the glass plate. This adhesive sheet S is suitable for bonding adherends with relatively high surface smoothness, such as glass substrates and cover glasses in display panels. Therefore, the adhesive sheet S is suitable for display panel use.

As described above, the adhesive sheet S is suitable for reducing environmental load and is suitable for display panel use.

The light transmittance R1 of the adhesive sheet S at a wavelength of 420 nm is 85% or more, and the light transmittance R2 at a wavelength of 380 nm is 15% or less. Such a configuration is preferable for ensuring the transparency required for the use of the adhesive sheet S in the display panel and ensuring the protection function of the display panel by cutting off ultraviolet rays. From the viewpoint of transparency, the light transmittance R1 is preferably at least 87%, more preferably at least 89%, and still more preferably at least 90%. The light transmittance R1 is substantially 99% or less. From the viewpoint of protective function, the light transmittance R2 is preferably at most 14%, more preferably at most 13%, more preferably at most 12%, more preferably at most 11%, more preferably at most 10%, more preferably at most 9% or less, more preferably 8% or less, more preferably 7% or less, more preferably 6% or less, more preferably 5% or less. Light transmittance R2 is substantially 0.1% or more. The method for measuring the light transmittance of the adhesive sheet S is as described in the examples below.

The haze of the adhesive sheet S is preferably 1% or less, more preferably 0.8% or less, further preferably 0.6% or less, especially preferably 0.4% or less. Such a configuration is preferable for suppressing light scattering in the adhesive sheet S and ensuring transparency required for display panel applications. The haze of the adhesive sheet S is, for example, 0.01% or more. The haze can be measured using a haze meter in accordance with JIS K7136 (2000). As a haze meter, "NDH2000" by Nippon Denshoku Industries Co., Ltd., and "HM-150 type" by Murakami Color Technology Laboratory Co., Ltd. are mentioned, for example.

The shear storage elastic modulus G1 of the adhesive sheet S at 25°C is preferably at most 0.2 MPa, more preferably at most 0.19 MPa, more preferably at most 0.18 MPa, more preferably at most 0.17 MPa, more preferably at most 0.16 MPa , more preferably at most 0.15 MPa, more preferably at most 0.14 MPa, more preferably at most 0.13 MPa, more preferably at most 0.12 MPa. Such a configuration is suitable for securing the step followability of the adhesive sheet S before photocuring. The shear storage modulus G1 is substantially 0.1 MPa or more. As a method of adjusting the shear storage elastic modulus G1, for example, selection of the type of the base polymer in the adhesive sheet S, adjustment of the molecular weight, and adjustment of the compounding amount may be mentioned. Selection of the type of base polymer includes adjustment of the composition of monomers forming the base polymer. Also, the method of measuring the shear storage elastic modulus G1 is as described in the examples below.

The shear storage elastic modulus G2 of the adhesive sheet S at 25°C after being hardened by irradiation with a cumulative light intensity of 3000 mJ/cm ² is preferably at least 0.21 MPa, more preferably at least 0.25 MPa, more preferably at least 0.26 MPa or more, more preferably 0.27 MPa or more, more preferably 0.28 MPa or more, more preferably 0.29 MPa or more, more preferably 0.30 MPa or more, more preferably 0.31 MPa or more, more preferably 0.32 MPa or more, more preferably 0.33 MPa Above, more preferably above 0.34 MPa, more preferably above 0.35 MPa, more preferably above 0.36 MPa, more preferably above 0.37 MPa, more preferably above 0.38 MPa, more preferably above 0.39 MPa, more preferably above 0.40 MPa, More preferably, it is at least 0.45 MPa, more preferably at least 0.5 MPa. Such a configuration is suitable for suppressing formation of air bubbles between the adherend and the adhesive sheet S in a state where the photocured adhesive sheet S is bonded to the adherend. The shear storage modulus G2 is substantially 1 MPa or less. As a method of adjusting the shear storage elastic modulus G2, for example, selection of the type of the base polymer in the adhesive sheet S, adjustment of the molecular weight, and adjustment of the compounding amount may be mentioned. As the adjustment method of the shear storage elastic modulus G2, selection of the kind of photopolymerizable multifunctional compound in the adhesive sheet S, adjustment of molecular weight, and adjustment of the compounding quantity are also mentioned. Also, the method for measuring the shear storage elastic modulus G2 is as described in the examples below.

The glass transition temperature of the adhesive sheet S after hardening by irradiation with a cumulative light intensity of 3000 mJ/ ^cm2 is preferably -3°C or lower, more preferably -4°C or lower, further preferably -5°C or lower, and further It is preferably below -6°C, especially preferably below -7°C. Such a configuration is preferable for ensuring the bonding reliability of the adhesive sheet S at low temperature. As a method of adjusting the glass transition temperature, for example, selection of the type of base polymer in the adhesive sheet S, adjustment of molecular weight, and adjustment of the compounding amount may be mentioned. Selection of the type of base polymer includes adjustment of the glass transition temperature of the base polymer. As a method of adjusting the glass transition temperature, selection of the kind of the photopolymerizable multifunctional compound in the adhesive sheet S, adjustment of the molecular weight, and adjustment of the compounding amount are also exemplified. In addition, the method of measuring the glass transition temperature of the adhesive sheet is as described below in relation to the examples.

The adhesive sheet S contains a base polymer as a photopolymer, a photopolymerizable polyfunctional compound (first photopolymerizable polyfunctional compound), and a photopolymerization initiator, and has photocurability. The adhesive sheet S may contain a monofunctional monomer as a polymerizable component other than a photopolymerizable polyfunctional compound. Photopolymers refer to polymers produced by photopolymerization. Photopolymerization refers to a polymerization method in which a polymerizable component undergoes a polymerization reaction by irradiating active energy rays such as ultraviolet rays. Photocurability refers to the property of high elasticity upon exposure to active energy rays such as ultraviolet rays.

The base polymer is a polymer obtained by photopolymerization of a polymerizable component including a monofunctional monomer and a photopolymerizable polyfunctional compound (second photopolymerizable polyfunctional compound). The base polymer is, for example, photopolymerization of a partial polymer (a mixture of a polymer of a monofunctional monomer and an unreacted monofunctional monomer) produced by photopolymerization of a monofunctional monomer and a second photopolymerizable polyfunctional compound obtained polymer. A monofunctional monomer may be used individually or in combination of 2 or more types. The 2nd photopolymerizable polyfunctional compound may be used individually, and may use 2 or more types together.

Such a base polymer includes a photopolymer (first photopolymer) having a photocrosslinked structure. The photocrosslinked structure is a structure obtained by crosslinking linear structures formed by units derived from a monofunctional monomer through units derived from a second photopolymerizable polyfunctional compound. The base polymer may also include a photopolymerizable polymer (second photopolymerizable polymer) not having such a photocrosslinked structure. The second photopolymerizable polymer is a polymer of a monofunctional monomer. Also, the base polymer is preferably an acrylic polymer. The acrylic polymer is a copolymer containing a polymerizable component of (meth)acrylate in a ratio of 50% by mass or more. "(Meth)acrylic acid" means acrylic acid and/or methacrylic acid.

As a monofunctional monomer, it is preferable to use a monofunctional (meth)acrylate. As the monofunctional (meth)acrylate, it is preferable to use an alkyl (meth)acrylate, and it is more preferable to use an alkyl (meth)acrylate whose alkyl group has 1 to 20 carbon atoms. Alkyl (meth)acrylate may have linear or branched alkyl groups, and may have cyclic alkyl groups such as alicyclic alkyl groups.

Examples of linear or branched alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, (meth)acrylate, base) isobutyl acrylate, second butyl (meth)acrylate, third butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, new (meth)acrylate Amyl ester, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, (meth)acrylate base) nonyl acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate Alkyl esters, Isotridecyl (meth)acrylate, Myristyl (meth)acrylate, Isotetradecyl (meth)acrylate, Pentadecyl (meth)acrylate, Cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl (meth)acrylate, and decadecyl (meth)acrylate nonalkyl esters.

Examples of alkyl (meth)acrylates having an alicyclic alkyl group include cycloalkyl (meth)acrylates, (meth)acrylates having a bicyclic aliphatic hydrocarbon ring, and (Meth)acrylate of aliphatic hydrocarbon ring with three or more rings. Examples of cycloalkyl (meth)acrylates include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclopentyl (meth)acrylate. Octyl esters. As (meth)acrylate which has a bicyclic aliphatic hydrocarbon ring, iso(meth)acrylate is mentioned, for example. Examples of (meth)acrylates having an aliphatic hydrocarbon ring having three or more rings include: dicyclopentanyl (meth)acrylate, dicyclopentyloxyethyl (meth)acrylate, (meth)acrylic acid Tricyclopentyl, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate ester.

As the alkyl (meth)acrylate, it is preferable to use an alkyl acrylate having an alkyl group having 3 to 15 carbon atoms, and it is more preferable to use an alkyl acrylate selected from n-butyl acrylate, 2-ethylhexyl acrylate, and acrylic acid. At least one member of the group consisting of lauryl esters.

The ratio of the monofunctional monomer in the polymerizable component forming the base polymer is preferably 50% by mass or more, more preferably 60% by mass, from the viewpoint of appropriately expressing basic properties such as adhesiveness of the adhesive sheet S. % by mass or more, more preferably at least 70% by mass, especially preferably at least 75% by mass. This ratio is, for example, 99% by mass or less.

The polymerizable component may contain, as a monofunctional monomer, a copolymerizable monomer copolymerizable with the aforementioned monofunctional monomer. As a copolymerizable monomer, the monomer which has a polar group is mentioned, for example. As the polar group-containing monomer, for example, a monomer having a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a ring containing a nitrogen atom may be mentioned. Monomers containing polar groups are helpful for the modification of acrylic polymers such as ensuring the cohesion of acrylic polymers.

Examples of the hydroxyl group-containing monomer include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxy (meth)acrylate - Hydroxypropyl, 4-Hydroxybutyl (meth)acrylate, 6-Hydroxyhexyl (meth)acrylate, 8-Hydroxyoctyl (meth)acrylate, 10-Hydroxydecyl (meth)acrylate, and 12-Hydroxylauryl (meth)acrylate. As the hydroxyl group-containing monomer, it is preferable to use at least one selected from the group consisting of 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate.

The ratio of the hydroxyl group-containing monomer in the polymerizable component is preferably at least 1% by mass, more preferably at least 3% by mass, and still more preferably at least 5% by mass, from the viewpoint of securing the cohesive force in the adhesive sheet S %above. From the viewpoint of adjusting the polarity of the acrylic polymer (compatibility between the various additive components in the adhesive sheet S and the acrylic polymer), the ratio is preferably 30% by mass or less, more preferably 20% by mass or less, more preferably 15% by mass or less.

Examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and methacrylic acid. .

The ratio of the carboxyl group-containing monomer in the polymerizable component is preferably 1% by mass or more from the viewpoint of ensuring the cohesion in the adhesive sheet S and the adhesion of the adhesive sheet S to the adherend Preferably, it is 3 mass % or more, More preferably, it is 5 mass % or more. From the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend due to acid, the ratio is preferably at most 20% by mass, more preferably at most 10% by mass.

Examples of monomers having a ring containing a nitrogen atom include: N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone , N-vinylpyrimidine, N-vinylpiperazole, N-vinylpyrrole, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryl- 2-pyrrolidone, N-(meth)acrylpiperidine, N-(meth)acrylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N- Vinyl-2-caprolactam, N-vinyl-1,3-㗁𠯤-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-ethylene Isoxazole, N-vinylthiazole, N-vinylisothiazole, and acrylmorpholine. The monomer having a nitrogen atom-containing ring is preferably at least one selected from the group consisting of N-vinyl-2-pyrrolidone and acrylmorpholine.

The ratio of the monomer having a nitrogen-atom-containing ring in the polymerizable component is preferably 1% by mass or more from the viewpoint of ensuring the cohesive force in the adhesive sheet and the adhesion of the adhesive sheet to the adherend , more preferably at least 3% by mass, further preferably at least 5% by mass. From the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (the compatibility of various additive components in the adhesive sheet with the acrylic polymer), the ratio is preferably 30 mass % or less, more preferably less than 20% by mass.

As a 2nd photopolymerizable polyfunctional compound, a polyfunctional monomer and a polyfunctional oligomer are mentioned, for example, It is preferable to use a polyfunctional oligomer.

As a polyfunctional monomer, the polyfunctional (meth)acrylate which has 2 or more ethylenically unsaturated double bonds in 1 molecule is mentioned, for example. As the polyfunctional monomer, a polyfunctional (meth)acrylate is preferable from the viewpoint of easily introducing a crosslinked structure by photopolymerization (active energy ray polymerization).

As a polyfunctional (meth)acrylate, a difunctional (meth)acrylate, a trifunctional (meth)acrylate, and a tetrafunctional or more polyfunctional (meth)acrylate are mentioned.

As the difunctional (meth)acrylate, for example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, Tetraethylene glycol dimethacrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, new Pentylene glycol di(meth)acrylate, stearic acid modified pentaerythritol di(meth)acrylate, dicyclopentenyl diacrylate, di(meth)acryl isocyanurate, and epoxy Alkane-modified bisphenol di(meth)acrylate.

Examples of trifunctional (meth)acrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and isocyanuric acid tris(acryloxyethyl) ester.

As the tetrafunctional or higher polyfunctional (meth)acrylate, for example, di-trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxy penta(meth)acrylate, base) acrylate, alkyl-modified dipentaerythritol pentaacrylate, and dipentaerythritol hexa(meth)acrylate.

The molecular weight of the polyfunctional monomer is preferably 5000 or less, more preferably 3000 or less, further preferably 2000 or less, especially preferably 1000 or less, and more preferably 200 or more. Such a constitution is preferable from the viewpoint of appropriately adjusting the viscoelasticity (for example, shear storage modulus and loss tangent) of the base polymer.

Examples of polyfunctional oligomers include urethane acrylate oligomers (oligomers having a urethane skeleton and two or more acryl groups), epoxy acrylate oligomers (an oligomer with an epoxy skeleton and two or more acryl groups), and a silicone acrylate oligomer (an oligomer with a siloxane skeleton and two or more acryl groups). As the polyfunctional oligomer, it is preferable to use an urethane acrylate oligomer. As a commercial item of a urethane acrylate oligomer, Artresin UN-333, UN-350, UN-353, UN-5500, and UN-5590 by Negami Kogyo Co., Ltd. are mentioned, for example.

The weight average molecular weight (Mw) of the polyfunctional oligomer is preferably at most 20,000, more preferably at most 15,000, and more preferably at least 5,000. Such a constitution is preferable from the viewpoint of appropriately adjusting the viscoelasticity (for example, shear storage modulus and loss tangent) of the base polymer. The weight-average molecular weight was measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

The ratio of the second photopolymerizable polyfunctional compound in the polymerizable component is preferably at least 0.1% by mass, more preferably at least 0.3% by mass, further preferably at least 0.5% by mass. Such a configuration is preferable for maintaining the sheet shape of the adhesive sheet S before photocuring, and thus is preferable for securing the handleability of the adhesive sheet S. The ratio of the second photopolymerizable polyfunctional compound in the polymerizable component is preferably at most 5 mass %, more preferably at most 3 mass %, still more preferably at most 2 mass %. Such a configuration is preferable for ensuring high flexibility of the adhesive sheet S before photocuring and achieving good step followability.

The polymerizable component may also contain other copolymerizable monomers. Examples of other copolymerizable monomers include acid anhydride monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic monomers. family of vinyl compounds. These other copolymerizable monomers may be used alone or in combination of two or more.

As a 1st photopolymerizable polyfunctional compound, a polyfunctional monomer and a polyfunctional oligomer are mentioned, for example, It is preferable to use a polyfunctional monomer. As a polyfunctional monomer, the polyfunctional monomer mentioned above about a 2nd photopolymerizable polyfunctional compound is mentioned, for example. As a polyfunctional oligomer, the polyfunctional oligomer mentioned above about a 2nd photopolymerizable polyfunctional compound is mentioned, for example. As a polyfunctional monomer, it is preferable to use trifunctional (meth)acrylate, more preferably to use trimethylolpropane tri(meth)acrylate, and further preferably to use trimethylolpropane triacrylate ( TMPTA).

The content of the first photopolymerizable polyfunctional compound in the adhesive sheet S is preferably at least 0.5 parts by mass, more preferably at least 0.8 parts by mass, further preferably at least 1 part by mass, based on 100 parts by mass of the base polymer, And preferably at most 20 parts by mass, more preferably at most 17 parts by mass, still more preferably at most 15 parts by mass. Such a configuration is suitable for ensuring good bonding reliability of the adhesive sheet S after photocuring.

As a photoinitiator, a radical photoinitiator, a cationic photoinitiator, and an anionic photoinitiator are mentioned, for example.

Examples of radical-based photopolymerization initiators include: acylphosphine oxide-based photopolymerization initiators, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based Photopolymerization initiator, aromatic sulfonyl chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzoyl-based photopolymerization initiator, benzophenone Photopolymerization initiator, ketal photopolymerization initiator, and 9-oxosulfur Department of photopolymerization initiator.

Examples of acylphosphine oxide-based photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl) base)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl base)-2,4,4-trimethylpentylphosphine oxide. Examples of benzoin ether-based photopolymerization initiators include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-1,2- Diphenylethan-1-one. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl Phenyl ketone, 4-phenoxydichloroacetophenone, and 4-(tert-butyl)dichloroacetophenone. Examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropane -1-one. As an aromatic sulfonyl chloride type photoinitiator, 2-naphthalenesulfonyl chloride is mentioned, for example. As a photoactive oxime photopolymerization initiator, 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime is mentioned, for example. Examples of the benzoin-based photopolymerization initiator include benzoin. As a benzoyl photopolymerization initiator, benzoyl is mentioned, for example. Examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, and polyvinyl Benzophenone. As a ketal type photoinitiator, benzoyl dimethyl ketal is mentioned, for example. as 9-oxosulfur It is a photopolymerization initiator, such as 9-oxosulfur , 2-Chloro9-oxosulfur 𠮿 , 2-methyl 9-oxosulfur 𠮿 , 2,4-Dimethyl 9-oxosulfur 𠮿 , Isopropyl 9-oxosulfur , 2,4-Diisopropyl 9-oxosulfur 𠮿 , and dodecyl 9-oxosulfur .

As a cationic photopolymerization initiator (photoacid generator), the onium compound which generate|occur|produces acid by ultraviolet-ray irradiation is mentioned, for example. The onium compound is provided, for example, in the form of an onium salt of an onium cation and anion. As the onium cation, for example, caldium and iodonium may be mentioned. Examples of anions include Cl ^- , Br ^- , I ^- , ZnCl ₃ ^- , HSO ₃ ^- , BF ₄ ^- , PF ₆ ^- , AsF ₆ - , SbF ₆ ^{- ,} CH ₃ SO ₃ ^- , CF ₃ SO ₃ ^- , C ₄ F ₉ HSO ₃ ^- , (C ₆ F ₅ ) ₄ B ^- , and (C ₄ H ₉ ) ₄ B ^- . Commercially available cationic photopolymerization initiators include, for example, CPI-100, CPI-100P, CPI-101A, CPI-200K, CPI-210S, IK-1, IK- 2. CPI-310B, and CPI-410S. Commercially available cationic photopolymerization initiators include, for example, SP-056, SP-066, SP-130, SP-140, SP-150, SP-170, and SP-171 manufactured by ADEKA Corporation. , and SP-172.

As an anionic photopolymerization initiator (photobase generator), the compound which has an α-amino acetophenone compound, an oxime ester compound, and a biguanide type cation is mentioned, for example. Examples of the biguanide cation include alkyl biguanide, cycloalkyl biguanide, and cycloalkyl-alkyl biguanide. As an anion paired with a biguanide type cation, a borate type anion is mentioned, for example. Examples of commercially available anionic photopolymerization initiators include WPBG-018 (9-anthracenemethyl N,N'-diethylcarbamate) and WPBG-027 manufactured by Fujifilm Corporation. ((E)-1-[3-(2-Hydroxyphenyl)-2-acryl]piperidine), WPBG-082 (2-(3-Benzylphenyl)guanidinium propionate), WPBG-140 (1-(anthraquinone-2-yl) ethyl imidazole carboxylate), WPBG-266 (2-(3-benzoylphenyl) propionic acid 1,2-diisopropyl-3 -[bis(dimethylamino)methylene]guanidinium), WPBG-300 (n-butyltriphenylboronic acid 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidinium ), and WPBG-345 (tetrakis(3-fluorophenyl)boronic acid 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanide).

The content of the photopolymerization initiator in the adhesive sheet S is preferably at least 0.01 parts by mass, more preferably at least 0.02 parts by mass, further preferably at least 0.03 parts by mass, still more preferably at least 0.03 parts by mass, based on 100 parts by mass of the base polymer. It is 0.05 mass part or more, More preferably, it is 0.07 mass part or more, Still more preferably, it is 0.1 mass part or more, Most preferably, it is 0.2 mass part or more. Such a constitution can significantly change the viscoelasticity of the adhesive sheet S by forming a cross-linked network structure with a sufficient cross-link density in the adhesive sheet S through the photopolymerization reaction when the adhesive sheet S is irradiated with light. better. The content of the photopolymerization initiator in the adhesive sheet S is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, further preferably 1 part by mass or less, based on 100 parts by mass of the base polymer. Such a constitution is preferable for suppressing the generation of a large number of polymerization initiators when the adhesive sheet S is irradiated with light, and for forming a long-distance and continuous cross-linked network structure by a photopolymerization reaction.

The adhesive sheet S may contain other components. Examples of other components include oligomers, ultraviolet absorbers, antioxidants, silane coupling agents, rust inhibitors, secondary processability improvers, isocyanate crosslinking agents, and metal deactivators.

When the base polymer is an acrylic polymer, it is preferable to use an acrylic oligomer as the oligomer. The acrylic oligomer is a copolymer containing a (meth)acrylate monomer component in a ratio of 50% by mass or more, and has a weight average molecular weight of, for example, 1,000 to 30,000.

The acrylic oligomer preferably contains an alkyl (meth)acrylate having a chain alkyl group (chain alkyl (meth)acrylate) and an alkyl (meth)acrylate having an alicyclic alkyl group. Polymer of ester (alicyclic alkyl (meth)acrylate) monomer component. Specific examples of such alkyl (meth)acrylates include, for example, the alkyl (meth)acrylates described above as the polymerizable component of the acrylic polymer.

As the chain alkyl (meth)acrylate, methyl methacrylate is preferable in terms of high glass transition temperature and excellent compatibility with the base polymer. As the alicyclic alkyl (meth)acrylate, dicyclopentyl acrylate, dicyclopentyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate are preferable. That is, the acrylic oligomer preferably contains at least one selected from the group consisting of dicyclopentanyl acrylate, dicyclopentanyl methacrylate, cyclohexyl acrylate, and cyclohexyl methacrylate, and Polymer of monomer component of methyl methacrylate.

The ratio of the alicyclic alkyl (meth)acrylate in the monomer component of the acrylic oligomer is preferably at least 10 mass %, more preferably at least 20 mass %, further preferably at least 30 mass %. The ratio is preferably at most 90% by mass, more preferably at most 80% by mass, further preferably at most 70% by mass. The ratio of the chain alkyl (meth)acrylate in the monomer component of the acrylic oligomer is preferably at most 90% by mass, more preferably at most 80% by mass, further preferably at most 70% by mass. The ratio is preferably at least 10 mass %, more preferably at least 20 mass %, further preferably at least 30 mass %.

The acrylic oligomer is obtained by polymerizing the monomer components of the acrylic oligomer. As a polymerization method, solution polymerization, block polymerization, and emulsion polymerization are mentioned, for example. Acrylic oligomers are preferably formed by solution polymerization. As a solvent in solution polymerization, toluene and ethyl acetate are mentioned, for example. In the polymerization of the acrylic oligomer, a thermal polymerization initiator may be used, and a chain transfer agent may be used for the purpose of adjusting the molecular weight. Moreover, in this embodiment, after formation of an acrylic oligomer, low molecular weight components and a solvent are volatilized and removed from reaction systems, such as a reaction solution, by heating. As a low molecular weight component, an unreacted monomer, a chain transfer agent, a thermal-polymerization initiator, and its decomposition product (residue) are mentioned, for example.

As a thermal polymerization initiator, an azo polymerization initiator and a peroxide polymerization initiator are mentioned, for example. As an azo polymerization initiator, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2 -Dimethyl methylpropionate, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) disalt salt, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropane amidine) disulfate, and 2,2'-azobis(N,N'-dimethyleneisobutylamidine) dihydrochloride. As a peroxide polymerization initiator, for example, dibenzoyl peroxide, t-butyl peroxymaleate, and lauryl peroxide may, for example, be mentioned.

As the chain transfer agent, α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, thioglycolic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolic acid, 2 , 3-dimercapto-1-propanol, and α-methylstyrene dimer.

The weight average molecular weight of the oligomer is preferably at least 1,000, more preferably at least 1,500, still more preferably at least 2,000. The molecular weight is preferably at most 30000, more preferably at most 10000, still more preferably at most 8000. The molecular weight range of such an oligomer is preferable for securing the adhesive force of the adhesive sheet S.

The content of the oligomer in the adhesive sheet S is preferably at least 0.5 parts by mass, more preferably at least 0.8 parts by mass, with respect to 100 parts by mass of the base polymer in order to sufficiently increase the adhesive force of the adhesive sheet S, and further Preferably it is 1 part by mass or more. The content of the oligomer in the adhesive sheet S is preferably 10 parts by mass or less, more preferably 7 parts by mass, based on 100 parts by mass of the base polymer, from the viewpoint of securing the transparency of the adhesive sheet S or less, more preferably 5 parts by mass or less, still more preferably 4 parts by mass or less, particularly preferably 3 parts by mass or less.

Examples of the ultraviolet absorber include: trioxane-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. absorbent. As the ultraviolet absorber, triazole-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are preferable in terms of high ultraviolet absorption in the wavelength range of 320 to 370 nm and excellent compatibility with acrylic polymers. UV absorber. The ultraviolet absorbent may be used alone or in combination of two or more.

Examples of commercially available trioxetin-based ultraviolet absorbers include: bisethylhexyloxyphenol methoxyphenyl trioxetin (trade name "Tinosorb S", manufactured by BASF), 2-(4,6- The reaction product of bis(2,4-dimethylphenyl)-1,3,5-tri-(2-yl)-5-hydroxyphenyl and [(alkoxy)methyl]oxirane ( Trade name "TINUVIN 400", manufactured by BASF), 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-trimethylphenyl) and Glycidyl acid (2-ethylhexyl) ester reaction product (trade name "TINUVIN 405", manufactured by BASF), (2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2 ,4-dibutoxyphenyl)-1,3,5-trimethanone (trade name "TINUVIN 460", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-trimethanone -2-yl)-5-[(hexyl)oxy]-phenol (trade name "TINUVIN 577", manufactured by BASF), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]benzene yl)-4,6-bis(4-phenylphenyl)-1,3,5-trimethanone (trade name "TINUVIN 479", manufactured by BASF), and 2-(4,6-diphenyl-1 ,3,5-Tri-(2-yl)-5-[2-(2-ethylhexyloxy)ethoxy]-phenol ("ADK STAB LA-46", manufactured by ADEKA).

Examples of commercially available benzotriazole-based UV absorbers include 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)- 4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928", manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzene Triazole (trade name "TINUVIN PS", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol ( Trade name "TINUVIN 900", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN 571", manufactured by BASF), 2 -(2H-benzotriazol-2-yl)-p-cresol (trade name "TINUVIN P", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-6-bis(1 -Methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6 -(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-amylphenol (trade name "TINUVIN 328", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 329", manufactured by BASF ), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimide-methyl)-5-methylphenyl]benzotriazole (trade name " Sumisorb 250", manufactured by Sumitomo Chemical).

In the adhesive sheet S, the specific absorbance (first specific absorbance) of the photopolymerization initiator at a wavelength of 405 nm is preferably 10 or more, more preferably 15 or more, and the specific absorbance of the ultraviolet absorber at a wavelength of 405 nm ( The second specific absorbance) is preferably 5 or less, more preferably 3 or less. Such a configuration is preferable from the viewpoint of both the UV cutoff function and photocurability for device protection of the adhesive sheet S. Among the photopolymerization initiators mentioned above, for example, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide The first specific absorbance is 15 or more. Among the above-mentioned ultraviolet absorbers, for example, bisethylhexyloxyphenol methoxyphenyl trisulfone, and 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenyl The second specific absorbance of ethyl)-4-(1,1,3,3-tetramethylbutyl)phenol is 3 or less.

The content of the ultraviolet absorber in the adhesive sheet S is preferably at least 0.05 parts by mass, more preferably at least 0.1 parts by mass, and preferably at most 3 parts by mass, more preferably at least 2 parts by mass, based on 100 parts by mass of the base polymer. servings or less. Such a configuration is preferable from the viewpoint of both the UV cutoff function and photocurability for device protection of the adhesive sheet S.

As an antioxidant, a phenolic antioxidant, a phosphorus antioxidant, a sulfur antioxidant, and an amine antioxidant are mentioned, for example. Antioxidants may be used alone or in combination of two or more.

As an antioxidant, it is preferable to use a phenolic antioxidant, and it is more preferable to use a hindered phenolic antioxidant. As hindered phenol antioxidants, for example, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (trade name "Irganox 1010", manufactured by BASF), 3 -(3,5-di-tert-butyl-4-hydroxyphenyl)octadecyl propionate (trade name "Irganox 1076", manufactured by BASF), 4,6-bis(dodecylthiomethyl) o-cresol (trade name "Irganox 1726", manufactured by BASF), triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] (trade name "Irganox 245 ", manufactured by BASF), bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (trade name "TINUVIN770", manufactured by BASF), and dimethyl succinate and 4- Polycondensation product of hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (trade name "TINUVIN622", manufactured by BASF).

The content of the antioxidant in the adhesive sheet S is preferably not less than 0.05 parts by mass, more preferably not less than 0.1 parts by mass, and preferably not more than 3 parts by mass, more preferably not more than 2 parts by mass, based on 100 parts by mass of the base polymer the following. Such a configuration is preferable from the viewpoint of both suppression of oxidative degradation of the adhesive sheet S and photocurability.

As a silane coupling agent, the silane coupling agent containing an epoxy group is mentioned, for example. Examples of the epoxy group-containing silane coupling agent include 3-glycidoxydialkyldialkoxysilane and 3-glycidoxyalkyltrialkoxysilane. As 3-glycidyloxydialkyldialkoxysilane, for example, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, base silane. As 3-glycidoxyalkyltrialkoxysilane, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane may be mentioned, for example. As the silane coupling agent, it is preferable to use 3-glycidoxyalkyltrialkoxysilane, more preferably to use 3-glycidoxypropyltrimethoxysilane. Silane coupling agents may be used alone or in combination of two or more. The content of the silane coupling agent in the adhesive sheet S is preferably not less than 0.1 parts by mass, more preferably not less than 0.2 parts by mass, and preferably not more than 5 parts by mass, more preferably not more than 3 parts by mass, based on 100 parts by mass of the base polymer. servings or less.

The adhesive sheet S does not substantially contain residues of thermal polymerization initiators. The residue of the thermal polymerization initiator includes decomposition products of the thermal polymerization initiator. The ratio of the thermal polymerization initiator residue in the adhesive sheet S is preferably at most 0.005% by mass, more preferably at most 0.001% by mass, and most preferably zero.

From the viewpoint of securing sufficient adhesiveness to the adherend, the thickness of the adhesive sheet S is preferably at least 10 μm, more preferably at least 15 μm. The thickness of the adhesive sheet S is preferably not more than 500 μm, more preferably not more than 400 μm, more preferably not more than 300 μm, more preferably not more than 250 μm, from the viewpoint of the handleability and laser processability of the adhesive sheet S Below, more preferably below 200 μm, more preferably below 150 μm, more preferably below 135 μm, more preferably below 100 μm, more preferably below 75 μm, more preferably below 50 μm.

The total light transmittance of the adhesive sheet S is preferably at least 90%, more preferably at least 92%. Such a constitution is preferable for securing the transparency required for the adhesive sheet S for display panels. The total light transmittance of the adhesive sheet S is, for example, 100% or less. The total light transmittance can be measured in accordance with JIS K 7375 (2008).

^The adhesive sheet S preferably has a gel fraction of 60% to 95%. The gel fraction is more preferably 65% or more, further preferably 68% or more, especially preferably 70% or more, and more preferably 92% or less, further preferably 90% or less, further preferably 88% or less , preferably below 86%. Such a configuration is suitable for suppressing formation of air bubbles between the adherend and the adhesive sheet S in a state where the photocured adhesive sheet S is bonded to the adherend. As a method of adjusting the gel fraction after photocuring, for example, selection of the type of the base polymer in the adhesive sheet S, adjustment of the molecular weight, and adjustment of the compounding amount may be mentioned. As the method of adjusting the gel fraction after photocuring, selection of the type of photopolymerizable multifunctional compound in the adhesive sheet S, adjustment of molecular weight, and adjustment of the compounding amount may also be mentioned. In addition, the method of measuring the gel fraction is as described below in relation to the examples.

The gel fraction of the adhesive sheet S (before photohardening) is preferably not less than 20% and not more than 65%. The gel fraction is more preferably 25% or more, more preferably 30% or more, especially preferably 35% or more, and more preferably 60% or less, more preferably 58% or less, more preferably 56% or less, and more preferably 56% or less. Preferably it is 54% or less, more preferably 52% or less, more preferably 50% or less, more preferably 48% or less, more preferably 46% or less. Such a configuration is preferable for suppressing dripping of the paste during processing of the adhesive sheet S, and is preferable for suppressing deformation of the adhesive sheet S during storage. As a method of adjusting the gel fraction before photocuring, for example, selection of the type of the base polymer in the adhesive sheet S, adjustment of the molecular weight, and adjustment of the compounding amount may be mentioned.

The loss tangent tanδ of the adhesive sheet S after being hardened by irradiation with a cumulative light intensity of 3000 mJ/cm ² preferably has a peak of 1.5 or more in the range of -40°C to 5°C. The peak value is more preferably 2 or more, further preferably 2.5 or more, particularly preferably 3 or more. Such a configuration is preferable from the viewpoint of low-temperature adhesion reliability of the adhesive sheet S. As a method of adjusting the peak top value, for example, adjustment of the composition ratio of the high Tg monomer in the base polymer and adjustment of the addition amount of the high Tg additive in the adhesive sheet S may be mentioned. The method for determining the loss tangent tan δ is as described below in relation to the examples. The loss tangent of the adhesive sheet can be measured, for example, using a dynamic viscoelasticity measuring device (trade name "Advanced Rheometric Expansion System (ARES)", manufactured by Rheometric Scientific). In this measurement, the measurement mode was set to the shear mode, the measurement temperature range was set to -50°C to 150°C, the temperature increase rate was set to 5°C/min, and the frequency was set to 1 Hz.

The adhesive sheet S is manufactured as follows, for example.

First, a prepolymer composition is prepared (prepolymer composition preparation step). Specifically, first, a mixture (liquid form) containing the above-mentioned monofunctional monomer for base polymer formation and a photopolymerization initiator is prepared. The mixture contains no solvent. Next, by irradiating the mixture with ultraviolet light, a part of the monofunctional monomer in the mixture is photopolymerized to obtain a prepolymer composition (solvent-free prepolymer composition). As a light source for ultraviolet irradiation, an ultraviolet LED lamp, a black light lamp, a high pressure mercury lamp, and a metal halide lamp are mentioned, for example. In addition, in ultraviolet irradiation, a wavelength cut filter for cutting part of the wavelength region of light emitted from the light source may be used as necessary. In ultraviolet irradiation, the illuminance is, for example, 5 to 200 mW/cm ² m, and the cumulative light intensity of irradiation is, for example, 100 to 5000 mJ/cm ² . The ultraviolet irradiation is preferably continued until the viscosity of the composition reaches about 15-25 Pa·s. The viscosity is set as a value measured with a B-type viscometer under the conditions of rotor No. 5, rotor rotation speed 10 rpm, and temperature 30°C. The prepolymer composition contains a photopolymer of a monofunctional monomer (the above-mentioned second photopolymerizable polymer) and a monofunctional monomer that has not been polymerized (residual monomer). Also, the prepolymer composition does not contain a solvent.

Next, a second photopolymerizable polyfunctional compound, a photopolymerization initiator, and other components as needed are added to the prepolymer composition to prepare an adhesive composition (adhesive composition preparation step). As another component, an antioxidant and a silane coupling agent are mentioned, for example. Since the adhesive composition does not contain a solvent, it is a solvent-free adhesive composition.

Next, as shown in FIG. 2A , the coating film 10 is formed between the release liners L1 and L2' (coating film forming step). Specifically, the adhesive composition is applied on the release liner L1 to form the coating film 10, and then the release liner L2' is bonded on the coating film 10 on the release liner L1.

The release liners L1, L2' are, for example, respectively flexible plastic films. As this plastic film, polyester films, such as a polyethylene terephthalate film, a polyethylene film, and a polypropylene film are mentioned, for example. The thickness of the release liner is, for example, 3 μm or more and, for example, 200 μm or less. The surface of the release liner is preferably subjected to a release treatment.

Examples of coating methods for the adhesive composition include roll coating, touch roll coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, and rod coating. Type coating, blade coating, air knife coating, curtain coating, die lip coating, and die coating.

Next, as shown in FIG. 2B , the coating film 10 between the release liners L1 and L2' is irradiated with ultraviolet light to be photocured to form a base adhesive sheet 10A (base adhesive sheet forming step). When ultraviolet rays are irradiated, a photopolymerization reaction including a reaction system of the above-mentioned residual monomers and the second photopolymerizable multifunctional compound proceeds in the coating film to form a first photopolymerizable polymer having a photocrosslinked structure.

Next, as shown in FIG. 2C , the release liner L2' is peeled from the base adhesive sheet 10A (peeling step).

Next, as shown in FIG. 2D , post-addition components are supplied to the base adhesive sheet 10A (post-addition component supply step). For example, a post-addition component solution (not shown) containing a post-addition component and a solvent is applied to the exposed surface of the base adhesive sheet 10A. The post-addition component includes a first photopolymerizable polyfunctional compound and a photopolymerization initiator, and may include additives such as a ultraviolet absorber or an antioxidant. Next, the solvent is vaporized by infiltrating the post-added component from the surface of the base adhesive sheet 10A into the base adhesive sheet 10A, and heating as necessary. Before this step, the base polymer already has a cross-linked structure to form the base adhesive sheet 10A. Therefore, it is difficult to form an orange peel surface on the base adhesive sheet 10A due to vaporization of the solvent in this step (substantially not formed). Moreover, the photocurable adhesive sheet S is formed by base adhesive sheet 10A and post-addition components. The amount of the first photopolymerizable polyfunctional compound added in this step is preferably 0.5 mass parts or more, more preferably 0.8 mass parts, relative to the total of 100 mass parts of the above-mentioned prepolymer composition and the second photopolymerizable polyfunctional compound It is more than 1 part by mass, more preferably 1 part by mass or less, more preferably 20 parts by mass or less, more preferably 17 parts by mass or less, further preferably 15 parts by mass or less. Such a configuration is suitable for ensuring good bonding reliability of the adhesive sheet S after photocuring.

Next, as shown in FIG. 2E , the release liner L2 is bonded to the adhesive sheet S (bonding step). As the release liner L2, for example, the plastic films described above with respect to the release liners L1 and L2' can be exemplified.

In this way, the adhesive sheet S whose adhesive surface is covered and protected by release liner L1, L2 can be manufactured. The release liners L1 and L2 are peeled from the adhesive sheet S when the adhesive sheet S is used as necessary.

3A to 3C show an example of how to use the adhesive sheet S. As shown in FIG.

In this method, first, as shown in FIG. 3A , the member 21 , the cover glass 22 , and the adhesive sheet S are prepared. The member 21 is, for example, a pixel panel for a display panel, a film-shaped polarizing plate (polarizing film), or a touch panel. The cover glass 22 has the 1st surface 22a by the side of the member 21, and the 2nd surface 22b which is the opposite side to this 1st surface 22a. The printed layer 23 for decoration or light shielding is formed in the edge of the 1st surface 22a. The printed layer 23 is provided, for example, over the entire circumference of the edge of the cover glass 22 . On the member 21 side of the cover glass 22, there is a level difference between the first surface 22a and the surface of the printed layer 23 (printing level difference).

Next, as shown in FIG. 3B , the one side in the thickness direction H of the member 21 and the other side in the thickness direction H of the cover glass 22 are bonded via the adhesive sheet S (bonding step).

Next, as shown in FIG. 3C , the adhesive sheet S is photohardened between members by ultraviolet irradiation (photohardening step). The photopolymerization reaction of the 1st photopolymerizable polyfunctional compound is performed in the adhesive sheet S by ultraviolet irradiation, and the photopolymer of the 1st photopolymerizable polyfunctional compound is formed. Since the photopolymerization reaction proceeds around the base polymer (the first photopolymerizable polymer having a photocrosslinked structure, the second photopolymerizable polymer), the photopolymer side of the first photopolymerizable polyfunctional compound is polymerized with the base polymer. The material forms an interpenetrating polymer network (IPN) on one side. Thereby, the adhesive sheet S is highly elasticized, and the bonding force between the member 21 and the cover glass 22 is improved. As a light source for ultraviolet irradiation, an ultraviolet LED lamp, a black light lamp, a high pressure mercury lamp, and a metal halide lamp are mentioned, for example. In addition, in ultraviolet irradiation, a wavelength cut filter for cutting part of the wavelength region of light emitted from the light source may be used. In ultraviolet irradiation, the irradiation cumulative light amount is, for example, 50 to 10000 mJ/cm ² .

The adhesive sheet S is as above-mentioned, and the base polymer is a photopolymer, and contains the 1st photopolymerization polymer which has a photocrosslinked structure. Such an adhesive sheet S can be produced from a solvent-free adhesive composition as described above. Moreover, with the solvent-free adhesive composition, in the process of producing the adhesive sheet S from the adhesive composition, there is no need for a drying step of vaporizing and removing the solvent from the coating film of the composition, so that the adhesive sheet S is not easily adhered. Orange peel-like bumps appear on the surface.

The adhesive sheet S contains the base polymer, the 1st photopolymerizable polyfunctional compound, and a photoinitiator as mentioned above. With regard to such an adhesive sheet S, the flexibility of the adhesive sheet S can be ensured when the adhesive sheet S (before photocuring) is used for bonding between adherends, and on the other hand, the first photopolymerizable The polyfunctional compound photopolymerizes and makes the adhesive sheet S highly elastic. This kind of adhesive sheet S is suitable for both the followability of the step difference on the surface of the adherends during the bonding between the adherends and the bonding reliability after the bonding between the adherends. [Example]

Hereinafter, an Example is shown and this invention is demonstrated concretely. However, this invention is not limited to an Example. In addition, the specific numerical values such as the blending amount (content), physical property values, and parameters described below can be replaced with the corresponding upper limits of the blending amount (content), physical property values, parameters, etc. described in the above-mentioned "embodiment" (defined as " A value that is "below" or "below") or a lower limit (defined as a value that is "above" or "exceeded").

＜Preparation of acrylic oligomer＞ First, in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction pipe, 60 parts by mass of dicyclopentanyl methacrylate (DCPMA), 40 parts by mass of methyl methacrylate (MMA), and A mixture of 3.5 parts by mass of α-thioglycerol as a chain transfer agent and 100 parts by mass of toluene as a polymerization solvent was stirred at 70° C. for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to the mixture as a thermal polymerization initiator to prepare a reaction solution, which was reacted at 70°C for 2 hours under a nitrogen atmosphere, and the After that, it was reacted at 80° C. for 2 hours (polymerization reaction). Next, by heating the reaction solution at 130° C., the toluene, chain transfer agent and unreacted monomers were volatilized and removed. Thereby, an acrylic oligomer (solid form) was obtained. The weight average molecular weight of this acrylic oligomer was 5100.

＜Preparation of prepolymer composition＞ In the flask, add 71 parts by mass of n-butyl acrylate (BA), 13 parts by mass of N-vinyl-2-pyrrolidone (NVP), 13 parts by mass of 4-hydroxybutyl acrylate (4HBA), and acrylic acid To a monomer mixture of 3 parts by mass of morpholine (ACMO), 0.031 parts by mass of the first photopolymerization initiator (trade name "Irgacure 184", 1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) and 0.031 parts by mass of the first photopolymerization initiator were added. 2 After 0.031 parts by mass of a photopolymerization initiator (trade name "Irgacure 651", 2,2-dimethoxy-1,2-diphenylethan-1-one, manufactured by BASF), the The mixture is irradiated with ultraviolet rays, whereby a part of the monomer components in the mixture are polymerized to obtain a prepolymer composition. The ultraviolet irradiation is continued until the viscosity of the composition reaches about 20 Pa·s. The viscosity is a value measured with a B-type viscometer under the conditions of rotor No.5, rotor speed 10 rpm, and temperature 30°C. The obtained prepolymer composition contains photopolymer (photopolymer P1a) and unpolymerized monomer components (residual monomer).

＜Preparation of Adhesive Composition＞ Next, 100 parts by mass of the prepolymer composition, 3 parts by mass of the above-mentioned acrylic oligomer, urethane acrylate oligomer (trade name "UN-350" Negami Industry Co., Ltd.) 0.6 parts by mass, the third photopolymerization initiator (trade name "Irgacure819", bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, manufactured by BASF) 0.4 Parts by mass, 0.5 parts by mass of antioxidant (trade name "Irganox 1010", manufactured by BASF), 0.2 parts by mass of antirust agent (trade name "BT-120", manufactured by Chengbei Chemical Industry Co., Ltd.), and silane coupling agent (trade name "KBM -403", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 parts by mass were mixed to obtain an adhesive composition C1.

<Preparation of basic adhesive sheet> Next, apply the adhesive composition on the release surface of the first release liner (trade name "DIAFOIL MRF", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release surface on one side C1 to form a coating film. Next, the release-treated surface of a second release liner (trade name "DIAFOIL MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was attached to the coating film on the first release liner. Next, the coating film between the release liners was irradiated with ultraviolet rays from the side of the second release liner to photocure the coating film to form an adhesive layer with a thickness of 100 μm (ultraviolet irradiation step). In the ultraviolet irradiation, a black light lamp (manufactured by Toshiba) was used as a light source, the illuminance was set to 6.5 mW/cm ² , and the irradiation cumulative light intensity was set to 1500 mJ/cm ² . In the ultraviolet irradiation step, the photopolymerization reaction of the system including the above-mentioned residual monomer and the second photopolymerizable polyfunctional compound proceeds in the coating film to form a photopolymerizable polymer P1b having a photocrosslinked structure. Also, since the photopolymerization reaction progresses around the photopolymer P1a, the photopolymer P1b is formed around the photopolymer P1a. The adhesive layer formed in this step includes the photopolymer P1a and the photopolymer P1b as the base polymer P1. In the above manner, a basic adhesive sheet with release liners on both sides (first release liner/basic adhesive sheet (thickness 100 μm)/second release liner) was prepared.

[Example 1] ＜Preparation of post-addition component solution＞ First, 5.8 parts by mass of a polyfunctional acrylate monomer (trade name "Viscoat #295", trimethylolpropane triacrylate (TMPTA), manufactured by Osaka Organic Chemical Industry Co., Ltd.) as the first photopolymerizable polyfunctional compound 0.3 parts by mass of a third photopolymerization initiator (trade name "Irgacure 819", manufactured by BASF), 7 parts by mass of an ultraviolet absorber (trade name "Tinosorb S", manufactured by BASF), and 94.2 parts by mass of ethyl acetate as a solvent Mixing is performed to prepare a post-addition component solution (other than the solvent in the solution is a post-addition component). Table 1 shows the composition of the post-addition component solution. In Table 1, the unit of the compounded amount of each component is relative "parts by mass".

＜Production of photocurable adhesive sheet＞ Next, after peeling the second release liner from the above-mentioned base adhesive sheet with release liners on both sides, the exposed surface of the base adhesive sheet was coated with a thickness of 20 μm, and the component solution was added (coating process ). For coating, a rod coater RDS No. 10 manufactured by R.D. SPECIALTIES was used. Next, dry in a dryer at 110°C for 60 seconds. By coating treatment and drying treatment, the post-added components (multifunctional acrylate monomer as the first photopolymerizable multifunctional compound, third photopolymerization initiator, ultraviolet absorber) are permeated into the base adhesive sheet, Also, the solvent is vaporized. The base adhesive sheet is changed into a light-curable adhesive sheet by penetration of post-added components. In this example, 1 part by mass of the first photopolymerizable polyfunctional compound was used as 1 part by mass relative to the total of 100 parts by mass of the prepolymer composition and the second photopolymerizable polyfunctional compound (that is, 100 parts by mass of the base polymer). The functional compound was added to the base adhesive sheet (the number by mass of the first photopolymerizable multifunctional compound relative to 100 parts by mass of the base polymer is shown in Tables 2 and 3). Next, a third release liner (trade name "DIAFOILMRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was attached to the photocurable adhesive sheet on the first release liner. Peel off treated side.

In the above manner, the photocurable adhesive sheet (1st release liner/photocurable adhesive sheet (thickness: 100 μm)/3rd release liner) of Example 1 with release liners on both sides was produced.

[Embodiments 2-6] The double-sided release liners of Examples 2 to 6 were produced in the same manner as the photocurable adhesive sheet with double-sided release liners of Example 1, except that the composition of the post-added component solution was changed to the composition shown in Table 1. Pad light hardening adhesive sheet.

[Examples 7 to 9, Comparative Example 1] Except that the composition of the post-addition component solution was changed to the composition shown in Table 1, and the coating treatment and subsequent drying treatment were performed twice, the light-curable adhesive sheet with a release liner attached to both sides of Example 1 was used. The photocurable adhesive sheets with release liners on both sides of Examples 7-9 and Comparative Example 1 were produced in the same manner.

[Comparative example 2] First, 64.5 parts by mass of n-butyl acrylate (BA), 6.0 parts by mass of cyclohexyl acrylate (CHA), N-vinyl-2- 9.6 parts by mass of pyrrolidone (NVP), 14.9 parts by mass of 4-hydroxybutyl acrylate (4HBA), 5.0 parts by mass of isostearyl acrylate, 2,2'-azobisisobutyronitrile as a thermal polymerization initiator (AIBN) 0.2 parts by mass, 0.065 parts by mass of α-thioglycerol as a chain transfer agent, and 233 parts by mass of ethyl acetate as a polymerization solvent were reacted at 56° C. for 5 hours while stirring under a nitrogen atmosphere, and then Reaction was carried out at 70° C. for 3 hours (polymerization). Thereby, a polymer solution containing an acrylic polymer was obtained.

Next, in the polymer solution, an isocyanate crosslinking agent (trade name "Takenate D110N", a trimethylolpropane adduct of xylylene diisocyanate, manufactured by Mitsui Chemicals Co., Ltd.) was mixed with respect to 100 parts by mass of the acrylic polymer. ) 0.1 parts by mass, 4.7 parts by mass of dipentaerythritol hexaacrylate (DPHA) as a polyfunctional acrylate monomer, 5 parts by mass of the above-mentioned acrylic oligomer, the first photopolymerization initiator (trade name "Irgacure184", BASF 0.2 parts by mass of silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.3 parts by mass of Adhesive Composition C2.

Next, adhesive composition C2 was applied to the release-treated surface of a first release liner (trade name "DIAFOIL MRF", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side to form a coating film. Next, the coating film on the first release liner was dried by heating at 100° C. for 3 minutes to form an adhesive layer with a thickness of 100 μm. Next, the release-treated surface of a second release liner (trade name "DIAFOIL MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) that had been released on one side was bonded to the adhesive layer on the first release liner. Thereafter, aging treatment was carried out at 25° C. for 3 days, and the crosslinking reaction of the acrylic polymer caused by the isocyanate crosslinking agent was carried out in the adhesive layer. The adhesive layer thus formed contained, as the base polymer P2, an acrylic polymer having a heat-crosslinked structure produced by an isocyanate crosslinking agent.

In the above manner, an adhesive sheet with release liners on both sides of Comparative Example 2 (first release liner/adhesive sheet (thickness 100 μm)/second release liner) was produced.

[Comparative example 3] ＜Preparation of Adhesive Composition＞ First, 100 parts by mass of the above-mentioned prepolymer composition, 0.4 parts by mass of a third photopolymerization initiator (trade name "Irgacure 819", manufactured by BASF), 5.8 parts by mass of the above-mentioned acrylic oligomer, urethane acrylic acid 1.1 parts by mass of ester oligomer (trade name "UN-350", manufactured by Negami Kogyo Co., Ltd.), 0.5 parts by mass of antioxidant (trade name "Irganox 1010", manufactured by BASF), rust inhibitor (trade name "BT-120", Johoku Chemical Industry Co., Ltd.) 0.2 parts by mass, silane coupling agent (trade name "KBM-403", Shin-Etsu Chemical Co., Ltd. Chemical Industry Co., Ltd.) 2 parts by mass were mixed to obtain an adhesive composition C3.

<Preparation of Adhesive Sheet> Next, apply the adhesive composition on the release-treated surface of the first release liner (trade name "DIAFOIL MRF", thickness 38 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side Object C3 to form a coating film. Next, the release-treated surface of a second release liner (trade name "DIAFOIL MRE", thickness 38 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was bonded on the coating film on the first release liner. Next, the coating film between the release liners was irradiated with ultraviolet rays from the side of the second release liner to photocure the coating film to form an adhesive layer with a thickness of 100 μm (ultraviolet irradiation step). In the ultraviolet irradiation, a black light lamp (manufactured by Toshiba) was used as a light source, the illuminance was set at 5 mW/cm ² , and the irradiation cumulative light intensity was set at 1500 mJ/cm ² . In the ultraviolet irradiation step, the photopolymerization reaction is carried out around the photopolymerizable polymer P1a in the coating film to form the photopolymerizable polymer P3b having a photocrosslinked structure. The adhesive layer formed in this step includes the photopolymer P1a and the photopolymer P3b as the base polymer P3.

In the above manner, the adhesive sheet with release liners on both sides of Comparative Example 3 (1st release liner/adhesive sheet (thickness 100 μm)/2nd release liner) was produced.

<Specific absorbance> Regarding the third photopolymerization initiator (trade name "Irgacure 819", manufactured by BASF) and ultraviolet absorber (trade name "Tinosorb S", manufactured by BASF), the specific absorbance at a wavelength of 405 nm was examined. Specifically, first, an ethyl acetate solution of a specific concentration of a sample (third photopolymerization initiator or ultraviolet absorber) is prepared as a sample solution. Next, the absorption spectrum of the sample solution was measured using a spectrophotometer (trade name "U4100", manufactured by Hitachi High-Tech). In this measurement, the temperature conditions were set at 23° C., the measurement cell length was set at 10 mm, and the measurement range wavelength was set at 300 to 500 nm. In addition, in the spectrophotometer, the absorbance (vertical axis) of the measured absorption spectrum was converted into specific absorbance (the specific absorbance is the absorbance when the sample concentration is 1 mg/mL and the measurement unit length is 1 cm). The specific absorbance E1 of the third photopolymerization initiator (trade name "Irgacure 819") at a wavelength of 405 nm was 18.2 (cm ^-1 ). The specific absorbance E2 of the ultraviolet absorber (trade name "Tinosorb S") at a wavelength of 405 nm is 3.4 (cm ^-1 ).

＜Gel fraction＞ About each adhesive sheet of Examples 1-9 and Comparative Examples 1-3, the gel fraction after photohardening was measured. Specifically, as follows.

First, ultraviolet rays are irradiated to the adhesive sheet between the release liners through the release liner. In the ultraviolet irradiation, a metal halide lamp was used as a light source, the illuminance was set to 300 mW/cm ² , and the cumulative light intensity of irradiation was set to 3000 mJ/cm ² . Second, about 1 g of the adhesive sample was collected from the adhesive sheet. Next, measure the mass (W ₁ ) of the adhesive sample. Next, the adhesive sample was immersed in 40 g of ethyl acetate in the container for 7 days. Next, all components (insoluble parts) that did not dissolve in ethyl acetate were collected. Next, the insoluble portion was dried at 130°C for 2 hours (removal of ethyl acetate). Next, the mass (W ₂ ) of the insoluble portion was measured. Then, the gel fraction of the adhesive sheet after photocuring was calculated based on the following formula. The values are shown in Tables 2 and 3.

Gel fraction (%)=(W ₂ /W ₁ )×100

＜Light transmittance＞ About each adhesive sheet of Examples 1-9 and Comparative Examples 1-3, the light transmittance was measured with the spectrophotometer (trade name "U4100", manufactured by Hitachi High-tech). In this measurement, after cutting out the sample piece (1st release liner/adhesive layer/3rd or 2nd release liner) from the adhesive sheet, the release liner is peeled off from both sides of the adhesive layer, and the adhesive Fix the adhesive layer to the measurement fixture of the spectrophotometer in such a way that the layer does not deform. In addition, in this measurement, the temperature condition was set to 23° C., and the measurement range wavelength was set to 300 to 800 nm. The measured light transmittance R1 (%) at a wavelength of 420 nm and the light transmittance R2 (%) at a wavelength of 380 nm are shown in Tables 2 and 3.

＜Haze＞ About each adhesive sheet of Examples 1-9 and Comparative Examples 1-3, the haze was measured with the haze meter (trade name "HM-150N", the Murakami Color Technology Laboratory Co., Ltd. make). In this measurement, after cutting out the sample piece (1st release liner/adhesive layer/3rd or 2nd release liner) from the adhesive sheet, the release liner is peeled off from both sides of the adhesive layer, and the adhesive Fix the adhesive layer on the measurement fixture of the haze meter in such a way that the layer does not deform. In addition, in this measurement, the temperature condition was made into 23 degreeC, and the light source equivalent to CIE standard light source D65 was used. Tables 2 and 3 show the measured haze (%).

＜Shear Storage Modulus, Glass Transition Temperature＞ Dynamic viscoelasticity was measured about each adhesive sheet (before photocuring) of Examples 1-9 and Comparative Examples 1-3 (1st measurement).

For each adhesive sheet, the required number of samples for measurement was prepared. Specifically, first, 20 adhesive sheet sheets cut out from the adhesive sheet were bonded together to prepare a sample sheet having a thickness of about 2 mm. Next, this sheet was punched to obtain cylindrical pellets (7.9 mm in diameter) as a sample for measurement.

Then, the dynamic viscoelasticity measurement was performed on the measurement sample by using a dynamic viscoelasticity measurement device (trade name "Advanced Rheometric Expansion System (ARES)", manufactured by Rheometric Scientific Co., Ltd.) after being fixed to a jig of a parallel plate with a diameter of 7.9 mm. . In this measurement, the measurement mode was set to the shear mode, the measurement temperature range was set to -50°C to 150°C, the temperature increase rate was set to 5°C/min, and the frequency was set to 1 Hz. The shear storage elastic modulus G1 (MPa) at 25° C. was read from the measurement results. The values are shown in Tables 2 and 3.

On the other hand, about each adhesive sheet of Examples 1-9 and Comparative Examples 1 and 2, the dynamic viscoelasticity after photocuring was measured (2nd measurement). When preparing samples for measurement, use an adhesive sheet that is photohardened by ultraviolet irradiation (in ultraviolet irradiation, use a metal halide lamp, set the illuminance to 300 mW/cm ² , and set the cumulative light intensity to 3000 mJ/ cm ² ). Except for this, the measurement apparatus and measurement conditions in the second measurement are the same as those in the above-mentioned first measurement. From the measurement results, the shear storage elastic modulus G2 (MPa) at 25° C. was read. Also, the temperature at which the loss tangent tan δ becomes maximum is defined as the glass transition temperature of the adhesive sheet (after photocuring). The equivalent values are shown in Tables 2 and 3.

＜Peel Strength＞ About each adhesive sheet in Examples 1-9 and Comparative Examples 1-3, the peeling strength F1 was measured by the following 1st test, and the peeling strength F2 was measured by the following 2nd test.

[First Test] First, a test piece was prepared for each adhesive sheet. In the preparation of the test piece, first, the third or second release liner was peeled off from the adhesive sheet, and a PET film (thickness 50 μm) was attached to the exposed surface of the adhesive sheet to obtain a laminated film (No. 1 release liner/adhesive sheet/PET film). Next, a test piece (width 10 mm×length 100 mm) was cut out from the laminated film. Next, in an environment of 23°C and a relative humidity of 50%, the first release liner was peeled off from the adhesive sheet of the test piece, and the exposed surface of the adhesive sheet exposed by this was attached to the surface of the test piece by the float method. The air side of the produced alkali glass plate (blue plate glass, manufactured by Matsunami Glass Industry Co., Ltd.) was used to obtain a laminate (alkali glass plate/adhesive sheet/PET film). The so-called air side refers to the exposed surface of the soda glass plate when the soda glass plate flows on the molten metal during the manufacturing process of the soda glass plate (the opposite side of the surface contacting the molten metal). In lamination, the test piece was crimp-bonded to the soda glass plate by reciprocating a 2 kg roller once (the same applies to the lamination described below). Next, the laminate is subjected to autoclave treatment (heating and pressure treatment). In the autoclave treatment, the temperature was set to 50° C., the pressure was set to 0.5 MPa, and the treatment time was set to 15 minutes. Next, the adhesive sheet in the laminate was irradiated with ultraviolet rays from the side of the alkali glass plate (light irradiation treatment). In the ultraviolet irradiation, a metal halide lamp was used as a light source, the illuminance was set to 300 mW/cm ² , and the cumulative light intensity of irradiation was set to 3000 mJ/cm ² . Next, the laminate was left to stand for 30 minutes in an environment of 23° C. and a relative humidity of 50%. Next, in an environment of 23°C and a relative humidity of 50%, a peeling test of peeling the test piece from the alkali glass plate was carried out to measure the peeling strength. In this measurement, a tensile tester (trade name "tensile compression tester TCM-1kNB", manufactured by Minebea Corporation) was used. In this measurement, the peeling angle of the test piece relative to the adherend is set to 180°, the tensile speed of the test piece is set to 300 mm/min, and the peeling length is set to 50 mm (measurement conditions of the peeling test). The measured peel strength F1 (N/10 mm) is shown in Tables 2 and 3.

[Second Test] First, a test piece was prepared for each adhesive sheet. In the preparation of the test piece, first, the third or second release liner was peeled off from the adhesive sheet, and a PET film (thickness 50 μm) was attached to the exposed surface of the adhesive sheet to obtain a laminated film (No. 1 release liner/adhesive sheet/PET film). Next, a test piece (width 10 mm×length 100 mm) was cut out from the laminated film. Next, the adhesive sheet in the test piece was irradiated with ultraviolet rays from the side of the first release liner (light irradiation treatment). In the ultraviolet irradiation, a metal halide lamp was used as a light source, the illuminance was set to 300 mW/cm ² , and the cumulative light intensity of irradiation was set to 3000 mJ/cm ² . Next, in an environment of 23°C and a relative humidity of 50%, the first release liner was peeled off from the adhesive sheet of the test piece, and the exposed surface of the adhesive sheet exposed by this was attached to the surface of the test piece by the float method. The soda glass plate (blue plate glass, manufactured by Matsunami Glass Industry Co., Ltd.) was produced to obtain a laminate (soda glass plate/adhesive sheet/PET film). Next, the laminate is subjected to autoclave treatment (heating and pressure treatment). In the autoclave treatment, the temperature was set to 50° C., the pressure was set to 0.5 MPa, and the treatment time was set to 15 minutes. Next, the laminate was left to stand for 30 minutes in an environment of 23° C. and a relative humidity of 50%. Next, in an environment of 23°C and a relative humidity of 50%, implement the peel test of the test piece peeled from the alkali glass plate to measure the peel strength. Tables 2 and 3 show the measured peel strength F2 (N/10 mm). Moreover, the ratio of the peeling strength F2 with respect to the peeling strength F1 is also shown in Tables 2 and 3.

＜Joining reliability＞ The bonding reliability of each adhesive sheet of Examples 1-9 and Comparative Examples 1-3 was examined as follows.

First, a second sample sheet (75 mm×45 mm) was cut out from an adhesive sheet with a release liner on both sides. Next, peel off the third or second release liner from the adhesive sheet in the second sample sheet, and attach the exposed surface of the adhesive sheet to a PET film (thickness 125 μm, 100 mm×50 mm ) of the center. For bonding, a roll laminator was used, the pressure between the rolls was set to 0.2 MPa, and the feed rate was set to 100 mm/min. Next, peel off the first release liner from the adhesive sheet on the PET film, and attach the exposed surface of the adhesive sheet to a glass plate with a printed layer (thickness 500 μm, length 100 mm x width 50 mm ), to obtain the laminate. FIG. 4 shows the positional relationship between the glass plate 41 and the adhesive sheet 42 in the laminate. On one side of the glass plate 41 in the thickness direction, a printed layer 43 (thickness 45 μm, black ink) was formed over the entire periphery of the edge of the glass plate 41 . The printed layer 43 is formed in the range of 15 mm inward from each end of the glass plate 41 in the longitudinal direction D1, and is formed in the range of 5 mm inward from each end of the glass plate 41 in the width direction D2. The adhesive sheet 42 is attached to the center of one side of the glass plate 41 in the thickness direction, and is in contact with the printed layer 43 over the entire circumference of the edge of the sheet. That is, the printed layer 43 on the glass plate 41 is sandwiched between the glass plate 41 and the adhesive sheet 42 within a range of 2.5 mm from the inner end of the layer to the outer side.

Next, the laminate was subjected to autoclave treatment for 30 minutes under the conditions of 50° C. and 0.5 MPa. Next, the adhesive sheet in the laminate is irradiated with ultraviolet rays from the glass plate side to photocure the adhesive sheet. In the ultraviolet irradiation, a metal halide lamp was used as a light source, the illuminance was set to 300 mW/cm ² , and the cumulative light intensity of irradiation was set to 3000 mJ/cm ² . Next, the laminate was left to stand for 24 hours at 23°C and a relative humidity of 50%. Next, the laminate was stored for 300 hours at 85°C and a relative humidity of 85%. Thereafter, the adhesive sheet in the laminate was observed along the edge with a magnifying glass. Then, with regard to the bonding reliability of the adhesive sheet, the case where no peeling or foaming occurred at the edge of the adhesive sheet was evaluated as "good", and the case where peeling or foaming occurred at the edge of the adhesive sheet (that is, Cases not evaluated as "good") were evaluated as "bad". The results are shown in Tables 2 and 3.

[Table 1] Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Comparative example 1 The first photopolymerizable polyfunctional compound (Viscoat#295) 5.8 11.6 17.4 28.9 40.5 57.9 31.8 34.7 43.4 57.9 Photopolymerization initiator (Irgacure819) 0.3 0.5 0.8 1.3 1.8 2.5 1.4 1.5 1.9 2.5 UV absorber (Tinosorb S) 7 7 7 7 7 7 3.5 3.5 3.5 3.5 Solvent (ethyl acetate) 94.2 88.4 82.6 71.1 59.5 42.1 68.2 65.3 56.6 42.1 Coating times 1 1 1 1 1 1 2 2 2 2

[Table 2] Table 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 method Solvent free Solvent free Solvent free Solvent free Solvent free Solvent free base polymer type P1 P1 P1 P1 P1 P1 cross-linked structure photocrosslinking photocrosslinking photocrosslinking photocrosslinking photocrosslinking photocrosslinking number of copies 100 100 100 100 100 100 The first photopolymerizable polyfunctional compound 1 (post-append) 2 (post added) 3 (added later) 4 (added after) 6 (added later) 9 (added later) Photohardening have have have have have have Types of cross-linked polymer structures after photohardening Photocrosslinking + Photocrosslinking Photocrosslinking + Photocrosslinking Photocrosslinking + Photocrosslinking Photocrosslinking + Photocrosslinking Photocrosslinking + Photocrosslinking Photocrosslinking + Photocrosslinking Gel fraction (%) 72 73 73 73 75 76 Light transmittance R1(%) at 420 nm 90 89 90 89 90 90 Light transmittance R2(%) at 380 nm 7 7 8 7 6 6 Haze (%) 0.4 0.4 0.4 0.4 0.4 0.4 Shear storage elastic modulus G1(MPa) before photohardening 0.15 0.15 0.15 0.15 0.15 0.15 Shear storage elastic modulus G2(MPa) after photohardening 0.15 0.20 0.26 0.33 0.39 0.48 Glass transition temperature after photohardening (°C) -11 -7 -5 -5 -5 -5 Peel strength F1(N/10mm) 7.8 6.4 6.3 6.1 5.5 2.9 Peel strength F2(N/10mm) 7.6 6.1 5.9 5.6 5.1 2.6 F2/F1 0.97 0.95 0.94 0.92 0.93 0.90 Bonding reliability good good good good good good

[table 3] table 3 Example 7 Example 8 Example 9 Comparative example 1 Comparative example 2 Comparative example 3 method Solvent free Solvent free Solvent free Solvent free Solvent type Solvent free base polymer type P1 P1 P1 P1 P2 P3 cross-linked structure photocrosslinking photocrosslinking photocrosslinking photocrosslinking thermal crosslinking photocrosslinking number of copies 100 100 100 100 100 100 The first photopolymerizable polyfunctional compound 10 (added later) 11 (added later) 13 (added later) 18 (added later) 4.7 2 Photohardening have have have have have none Types of cross-linked polymer structures after photohardening Photocrosslinking + Photocrosslinking Photocrosslinking + Photocrosslinking Photocrosslinking + Photocrosslinking Photocrosslinking + Photocrosslinking thermal crosslinking + photocrosslinking photocrosslinking Gel fraction (%) 77 77 78 78 80 88 Light transmittance R1(%) at 420 nm 90 89 90 90 89 90 Light transmittance R2(%) at 380 nm 7 8 9 9 88 89 Haze (%) 0.4 0.4 0.4 0.4 0.4 0.4 Shear storage elastic modulus G1(MPa) before photohardening 0.15 0.14 0.14 0.13 0.12 0.28 Shear storage elastic modulus G2(MPa) after photohardening 0.51 0.53 0.67 0.85 0.22 - Glass transition temperature after photohardening (°C) -5 -4 -3 -2 -9 - Peel strength F1(N/10mm) 2.2 1.9 1.6 1.0 6.0 0.2 Peel strength F2(N/10mm) 2.0 1.8 1.5 0.8 5.6 0.2 F2/F1 0.91 0.95 0.94 0.8 0.93 1.0 Bonding reliability good good good bad good bad

10: Coating film 10A: Basic adhesive sheet 21: Component 22: cover glass 22a:Side 1 22b:Side 2 23: Printing layer 41: glass plate 42: Adhesive sheet 43: Printing layer D1: Length direction D2: Width direction H: Thickness direction L1: Release liner L2: Release liner L2': Release liner S: Adhesive sheet (photocurable adhesive sheet)

Fig. 1 is a schematic cross-sectional view of an embodiment of the photocurable adhesive sheet of the present invention. 2A to 2E show an example of a method of manufacturing the photocurable adhesive sheet shown in FIG. 1 . Fig. 2A shows the step of forming the coating film of the adhesive composition, Fig. 2B shows the step of forming the base adhesive sheet, Fig. 2C shows the step of peeling the light release liner, and Fig. 2D shows the step of adding components after supplying the base adhesive sheet, Fig. 2E represents the step of attaching the light release liner to the sheet. 3A to 3C show an example of a method of using the photocurable adhesive sheet shown in FIG. 1 . Fig. 3A shows the step of preparing a photocurable adhesive sheet and two members (adhered bodies), Fig. 3B shows a step of bonding the members to each other through the photocurable adhesive sheet, and Fig. 3C shows the step of making the photocurable adhesive sheet in The step of photohardening between components. FIG. 4 shows the positional relationship between the glass plate and the adhesive sheet in the laminate used for the evaluation of the step followability in Examples and Comparative Examples.

H: Thickness direction

L1: Release liner

L2: Release liner

S: Adhesive sheet (photocurable adhesive sheet)

Claims (8)

A photocurable adhesive sheet comprising a base polymer as a photopolymer and having photocurability, and after affixing the photocurable adhesive sheet to an alkali glass plate produced by a float method, it Then heat and pressurize the photocurable adhesive sheet on the soda glass plate under the conditions of 50°C, 0.5 MPa and ¹⁵ minutes. After the curable adhesive sheet is subjected to photohardening treatment, the above photohardenable adhesive sheet is peeled from the above alkali glass plate under the conditions of 23°C, relative humidity of 50%, peeling angle of 180° and tensile speed of 300 mm/min. In the peel test, it has a peel strength of 1.5 N/10 mm or more. Such as the photocurable adhesive sheet of claim 1, wherein the above photocurable adhesive sheet is subjected to photohardening treatment under the condition of irradiating a cumulative light amount of 3000 mJ/cm ² , and then the above photocurable adhesive sheet is pasted Applicable to the alkali glass plate produced by the float method, and then heat and pressurize the above-mentioned light-curable adhesive sheet on the above-mentioned alkali glass plate under the conditions of 50 ° C, 0.5 MPa and 15 minutes, and then In the peeling test of peeling the above-mentioned photocurable adhesive sheet from the above-mentioned soda glass plate under the conditions of 23°C, relative humidity of 50%, peeling angle of 180° and tensile speed of 300 mm/min, it has a strength of 1.5 N/10 mm or more. Peel strength. A photocurable adhesive sheet comprising a base polymer as a photopolymer and having photocurability, and subjecting the above photocurable adhesive sheet to photohardening treatment under the condition of irradiating a cumulative light amount of 3000 mJ/cm ² , Thereafter, the above-mentioned light-curable adhesive sheet was bonded to the alkali glass plate produced by the float method, and then the above-mentioned light-hardenable adhesive sheet on the above-mentioned alkali glass plate was tested under the conditions of 50 ° C, 0.5 MPa and 15 minutes. After the adhesive sheet is subjected to heat and pressure treatment, the above-mentioned light-curable adhesive sheet is peeled from the above-mentioned soda glass plate under the conditions of 23°C, relative humidity of 50%, peeling angle of 180°, and tensile speed of 300 mm/min. In the test, it has a peel strength of 1.5 N/10 mm or more. According to any one of claims 1 to 3, the light-curable adhesive sheet has a light transmittance of 85% or more at a wavelength of 420 nm, and a light transmittance of 15% or less at a wavelength of 380 nm. The photocurable adhesive sheet according to any one of Claims 1 to 3, which has a haze of 1% or less. The photocurable adhesive sheet according to any one of Claims 1 to 3, which has a shear storage elastic modulus of 0.2 MPa or less at 25°C. The light-curable adhesive sheet according to any one of Claims 1 to 3, which has a shear storage elasticity of 0.21 MPa or more at 25°C after being hardened by irradiating a cumulative light intensity of 3000 mJ/cm ² Modulus. The photocurable adhesive sheet according to any one of Claims 1 to 3, which has a glass transition temperature of -3°C or lower after being hardened by irradiation with a cumulative light intensity of 3000 mJ/cm ² .