JP7339782B2 - Optical adhesive sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical pressure-sensitive adhesive sheet and the like.

2. Description of the Related Art In electronic devices, adhesive sheets are used to fix various members. For example, in a light-emitting/light-receiving device (optical device) such as a touch panel module, a display module, and a camera module, members are sometimes bonded using a transparent adhesive sheet.

In recent years, the use of organic EL displays has been increasing, but since organic EL displays are susceptible to adverse effects from moisture, styrene-based block adhesives have been replaced with acrylic adhesives, which have been widely used in the past, as adhesives for adhesive sheets. A rubber adhesive such as a copolymer may be used. For example, Patent Literature 1 discloses an adhesive sheet containing a rubber-based polymer as an adhesive and having a certain or less moisture permeability.

Japanese Patent Application Laid-Open No. 2017-057382

As in the technique disclosed in Patent Literature 1, in order to suppress the adverse effects of moisture, it is conceivable to design the pressure-sensitive adhesive sheet to be impervious to moisture. However, in electronic devices (especially organic EL devices), in order to prevent moisture from entering from the outside, the entire device including the adhesive sheet is often sealed and hermetically sealed with a material having low moisture permeability such as glass. In such a case, if the remaining moisture is released from the surrounding members, this moisture has nowhere else to go in the sealed space, so even if the adhesive sheet itself is resistant to moisture, it is vulnerable to other members and moisture. This will have a detrimental effect on the parts. Specifically, moisture may condense in the interface region between the layers, causing whitening and degrading the display quality.

Accordingly, an object of the present invention is to provide an optical pressure-sensitive adhesive sheet containing a styrenic block copolymer, which is excellent in whitening resistance.

The inventor of the present invention has focused on water content (moisture retention performance under a specific environment) and moisture permeability in the course of research. Then, through further intensive research, the inventors have found that excellent whitening resistance can be achieved by controlling these to relatively high values, and have completed the present invention.

That is, the present invention includes the following aspects.

Section 1. including an adhesive layer (A) containing a styrenic block copolymer,
The adhesive layer (A) has a water content of 0.10 to 0.25% by mass after standing at 65 ° C. 90% RH for 3 days, and the moisture permeability of the adhesive layer (A) at 65 ° C. 90% RH. is 350 to 1000 g/m ² day,
Optical adhesive sheet.

Section 2. Item 2. The optical pressure-sensitive adhesive sheet according to Item 1, wherein the content of the softening agent in the pressure-sensitive adhesive layer (A) is 0 to 15% by weight with respect to 100% by weight of the pressure-sensitive adhesive layer (A).

Item 3. Item 3. The optical pressure-sensitive adhesive sheet according to Item 1 or 2, wherein the pressure-sensitive adhesive layer (A) contains a tackifier.

Section 4. The tackifier is a tackifier having a softening point of 85 ° C. or higher and an aromatic ring, and the content of the tackifier in the adhesive layer (A) is 100 mass of the adhesive layer (A) Item 4. The optical pressure-sensitive adhesive sheet according to Item 3, which is 40% by mass or less with respect to %.

Item 5. Item 5. The optical application according to any one of Items 1 to 4, wherein the content of the styrene block copolymer in the adhesive layer (A) is 45 to 85% by mass with respect to 100% by mass of the adhesive layer (A). adhesive sheet.

Item 6. Item 6. The optical pressure-sensitive adhesive sheet according to any one of Items 1 to 5, wherein the styrene content in the styrenic block copolymer is 10 to 50% by mass.

Item 7. A laminate comprising the optical pressure-sensitive adhesive sheet according to any one of Items 1 to 6 and an adherend disposed on the optical pressure-sensitive adhesive sheet.

Item 8. The optical pressure-sensitive adhesive sheet according to any one of Items 1 to 6, a first adherend laminated on the first surface of the optical pressure-sensitive adhesive sheet, and the first surface of the optical pressure-sensitive adhesive sheet. and a second adherend laminated to the opposite second surface.

Item 9. The first adherend is an antireflection film, a shatterproof film, a cover panel, a film with a metal or metal oxide thin film, a glass with a metal or metal oxide thin film, a superbirefringent film, or a touch panel module, and Item 8, wherein the second adherend is a cover panel, a film with a metal or metal oxide thin film, glass with a metal or metal oxide thin film, a super-birefringent film, a touch panel module, a polarizing plate, or a display panel module. Laminate as described.

Item 10. On one side of a transparent conductive film having a transparent conductive thin film formed of a metal oxide on one side of a transparent plastic film substrate and a functional layer on the other side, any of Items 1 to 6 A transparent conductive film with a pressure-sensitive adhesive layer comprising the optical pressure-sensitive adhesive sheet according to 1.

Item 11. Item 11. The transparent conductive film with a pressure-sensitive adhesive layer according to Item 10, further comprising the optical pressure-sensitive adhesive sheet on the transparent conductive thin film of the transparent conductive film.

Item 12. Item 12. The transparent conductive film with a pressure-sensitive adhesive layer according to Item 11, further comprising the optical pressure-sensitive adhesive sheet on the functional layer of the transparent conductive film.

Item 13. A touch panel comprising at least one pressure-sensitive adhesive layer-attached transparent conductive film according to any one of items 10 to 12.

ADVANTAGE OF THE INVENTION According to this invention, the optical adhesive sheet containing the styrenic block copolymer excellent in whitening resistance can be provided.

(a) It is a schematic sectional drawing which shows an example of the transparent conductive film with an adhesive layer to which the optical adhesive sheet of this invention is applied. (b) It is a schematic sectional drawing which shows an example of the transparent conductive film with an adhesive layer to which the optical adhesive sheet of this invention is applied. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an example of a capacitive touch panel to which the optical pressure-sensitive adhesive sheet of the present invention is applied in relation to a transparent conductive film.

As used herein, the expressions "contain" and "include" include the concepts "contain", "include", "consist essentially of" and "consist only of".

1. The optical pressure-sensitive adhesive sheet of the present invention, as one aspect thereof, comprises a pressure-sensitive adhesive layer (A) containing a styrenic block copolymer, and a water-containing pressure-sensitive adhesive layer (A) after standing at 65° C. and 90% RH for 3 days. is 0.10 to 0.25% by mass, and the pressure-sensitive adhesive layer (A) has a moisture permeability of 350 to 1000 g/m ² ·day at 65 ° C. 90% RH (this specification , sometimes referred to as "the optical pressure-sensitive adhesive sheet of the present invention"). This will be explained below.

The adhesive layer (A) contains a styrenic block copolymer as an adhesive.

The styrenic block copolymer is not particularly limited as long as it can be used as an adhesive for adhesive sheets. Examples of styrene block copolymers include styrene-(ethylene-propylene)-styrene block copolymer (SEPS), styrene-(ethylene-butylene)-styrene block copolymer (SEBS), styrene-(butadiene -butylene)-styrene type block copolymer (SBBS), styrene-based triblock copolymer such as styrene-isobutylene-styrene type block copolymer (SIBS). Other examples of styrenic block copolymers include styrene-(ethylene-propylene) type block copolymers (SEP), styrene-(ethylene-butylene) type block copolymers (SEB), styrene-(butadiene- butylene) type block copolymer (SBB), styrene-isobutylene type block copolymer (SIB) and other styrene diblock copolymers. Among these examples, styrenic triblock copolymers are preferred, and SEPS, SEBS and the like are more preferred.

The weight average molecular weight of the styrenic block copolymer is not particularly limited as long as it can be used as an adhesive for adhesive sheets. The weight average molecular weight is, for example, 10,000 to 2,000,000, preferably 30,000 to 500,000.

The styrene content of the styrenic block copolymer is, for example, 10 to 50% by mass, preferably 15 to 50% by mass, more preferably 15 to 40% by mass, still more preferably 15 to 35% by mass. By increasing the styrene content, the water content and moisture permeability can be increased.

The styrenic block copolymer also includes various modified products. As the modified product, a modified product that has undergone modification to further increase polarity is preferred. By using such a modified material, the water content and moisture permeability can be further increased. Modified compounds include, for example, acid-modified compounds and amine-modified compounds. The degree of modification may vary depending on the type of modification and the like. For example, in the case of an acid-modified product, its acid value (mgCH3ONa/g) is, for example, 2-15, preferably 4-10.

The styrenic block copolymer may be used singly or in combination of two or more. When combining a styrenic triblock copolymer and a styrenic diblock copolymer, both should have the same structure from the viewpoint of compatibility (for example, when the styrenic triblock copolymer is SEPS, The styrenic diblock copolymer is preferably SEP). In addition, when using a highly polar modified body (highly polar modified body) such as an acid modified body as the styrenic block copolymer, a non-modified body is optionally combined (for example, 100 parts by mass of the highly polar modified body On the other hand, for example, 50 to 300 parts by mass of the unmodified body, preferably 100 to 200 parts by mass, more preferably 130 to 170 parts by mass), by using characteristics, etc. can be set within an appropriate range.

The content of the styrenic block copolymer in the adhesive layer (A) is not particularly limited. It is preferably 50 to 80% by mass.

The adhesive layer (A) is not particularly limited as long as it mainly contains a styrene-based block copolymer as an adhesive, and may contain only a styrene-based block copolymer as an adhesive, or may contain other adhesives. It may contain an agent. Examples of other adhesives include acrylic adhesives, urethane adhesives, polyolefin adhesives, polyester adhesives, vinyl alkyl ether adhesives, polyamide adhesives, silicone adhesives, and fluorine adhesives. is mentioned. When the adhesive layer (A) contains another adhesive, the content of the other adhesive is, for example, 0 to 10% by mass, preferably 0 to 5% by mass, relative to 100% by mass of the adhesive layer (A). , more preferably 0 to 1% by mass.

The adhesive layer (A) preferably contains a tackifier.

The tackifier is not particularly limited as long as it can be used for pressure-sensitive adhesive sheets, particularly pressure-sensitive adhesive sheets containing a styrenic block copolymer as the pressure-sensitive adhesive. Examples of the tackifier include petroleum resins, styrene resins, rosin skeleton-containing resins, terpene skeleton-containing resins, etc., preferably petroleum resins, styrene resins, etc., more preferably petroleum resins. . The tackifier preferably has an aromatic ring from the viewpoint of whitening resistance and the like.

Examples of tackifiers having an aromatic ring include aromatic petroleum resins, styrene polymers, α-methylstyrene polymers, styrene-(α-methylstyrene) copolymers, styrene-aliphatic hydrocarbons. copolymers, styrene-(α-methylstyrene)-aliphatic hydrocarbon copolymers, styrene-aromatic hydrocarbon copolymers, and the like. Among these, from the viewpoint of whitening resistance, styrene-aromatic hydrocarbon copolymers, styrene-aliphatic hydrocarbon copolymers, etc. are preferred, and styrene-aromatic hydrocarbon copolymers are more preferred. A copolymer is mentioned.

The softening point of the tackifier is not particularly limited, and is within a range that can be used as a tackifier. The softening point is, for example, 85°C or higher, preferably 85 to 200°C, more preferably 100 to 170°C, still more preferably 120 to 160°C. As used herein, the softening point is a value measured by the test method specified in JISK2207.

The tackifier may be used alone or in combination of two or more.

The content of the tackifier in the adhesive layer (A) is not particularly limited, but is, for example, 40% by mass or less, preferably 5 to 40% by mass, more preferably 10 to 100% by mass with respect to 100% by mass of the adhesive layer (A). 40% by mass, more preferably 15 to 40% by mass.

The adhesive layer (A) may contain a softener.

The softener is not particularly limited as long as it can be used for pressure-sensitive adhesive sheets, particularly pressure-sensitive adhesive sheets containing a styrenic block copolymer as an adhesive. As the softening agent, typically, a substance that is liquid at room temperature (23° C.) and compatible with the soft segment of the styrenic block copolymer, such as an oligomer composed only of hydrocarbon groups, can be used. can. Specific examples of softening agents include polyisobutylene, polyisoprene, polybutadiene, polybutene, etc., as well as polymers obtained by arbitrarily combining these constituent monomers and other monomers. Among these, polyisobutylene is preferred.

Although the number average molecular weight of the softening agent is not particularly limited, it is, for example, 300-3000.

The softening agent may be used singly or in combination of two or more.

The content of the softening agent in the adhesive layer (A) is, for example, 0 to 15% by mass, preferably 0 to 13% by mass, based on 100% by mass of the adhesive layer (A). By setting the softener content to a relatively low level, the water content and moisture permeability can be further increased.

The adhesive layer (A) may contain components other than the above as long as they do not significantly worsen the whitening. Other components include, for example, silane coupling agents, polymerization initiators, cross-linking agents, antioxidants, cross-linking accelerators, antistatic agents, light stabilizers (absorbers), dispersion stabilizers, preservatives, viscosity modifiers, Examples include metal corrosion inhibitors, plasticizers, solvents, and the like.

Other components may be used singly or in combination of two or more.

The content of other components in the adhesive layer (A) is, for example, 0 to 10% by mass, preferably 0 to 5% by mass, more preferably 0 to 1% by mass, relative to 100% by mass of the adhesive layer (A). be.

The adhesive layer (A) has a moisture content of 0.10 to 0.25% by mass after standing at 65° C. and 90% RH for 3 days. Let X (unit: g) be the mass of the adhesive layer (A) before standing at 65°C and 90% RH for 3 days, and the water content in the adhesive layer (A) after standing at 65°C and 90% RH for 3 days. When Y (unit: g), the water content can be calculated by the following formula [water content = (Y/X) x 100 (%)]. The water content is measured by the Karl Fischer method. Further, X is normal temperature (eg, 15 to 30 ° C., preferably 20 to 25 ° C.) and normal humidity (eg, 35 to 65% RH, preferably 45 to 55% RH) for a certain period of time (eg, 1 day or more, preferably 1 to 5 days, more preferably 2 to 4 days), and then the values are preferably measured.

By setting the moisture content within the above range, the whitening resistance can be further improved, and in particular, the occurrence of whitening can be suppressed.

The water content is preferably 0.12 to 0.25% by mass, more preferably 0.15 to 0.25% by mass, from the viewpoint of whitening resistance.

The adhesive layer (A) has a moisture permeability of 350 to 1000 g/m ² ·day at 65°C and 90% RH. The moisture permeability is measured under conditions of a temperature of 65° C. and a humidity of 90% RH in accordance with JIS Z 0208 (moisture-proof packaging material moisture permeability test method (cup method)).

By setting the moisture permeability within the above range, the whitening resistance can be further improved, and in particular, the disappearance of whitening after occurrence of whitening can be promoted.

The moisture permeability is preferably 365 g/m ² ·day or more, more preferably 450 g/m ² ·day or more, still more preferably 570 g/m ² ·day or more.

The thickness of the adhesive layer (A) is not particularly limited as long as it does not impair the transparency, etc., and can be appropriately set according to the application. The thickness is, for example, 1 to 100 μm, preferably 5 to 50 μm, more preferably 10 to 40 μm.

The layer structure of the adhesive layer (A) is not particularly limited. The adhesive layer (A) may be a single layer consisting of one layer, or may be a plurality of layers having the same or different compositions.

The optical pressure-sensitive adhesive sheet of the present invention may contain only the pressure-sensitive adhesive layer (A) as the pressure-sensitive adhesive layer, or may contain pressure-sensitive adhesive layers other than the pressure-sensitive adhesive layer (A). In the latter case, the thickness of the other adhesive layer is not particularly limited as long as it does not impair the transparency of the entire adhesive layer. More preferably, the thickness is 10 to 40 μm. Moreover, the layer structure of the other adhesive layer is not particularly limited, and may be a single layer consisting of one layer, or may be a plurality of layers having the same or different compositions. When other adhesive layers are included, a plurality of adhesive layers (A) may be arranged in the adhesive layer via other adhesive layers. Moreover, when another adhesion layer is included, it is preferable that the adhesion layer (A) is arrange|positioned at the outermost layer of an adhesion layer.

The layer structure of the optical pressure-sensitive adhesive sheet of the present invention is not particularly limited as long as it includes a pressure-sensitive adhesive layer. Specifically, the optical pressure-sensitive adhesive sheet of the present invention includes, for example, (1) a substrate-less double-sided pressure-sensitive adhesive sheet having a configuration formed only from an adhesive layer, and (2) a substrate disposed on the adhesive layer. A pressure-sensitive adhesive sheet with a substrate (for example, (2-1) a double-sided pressure-sensitive adhesive sheet with a substrate having a configuration in which an adhesive layer is formed on at least one surface of the substrate and adhesive surfaces are formed on both sides of the substrate, (2 -2) A pressure-sensitive adhesive sheet with a substrate having a pressure-sensitive adhesive layer formed on one side of the substrate). When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet with a substrate, the pressure-sensitive adhesive layer (adhesive layer) formed on both sides of the substrate may be the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer formed on one side of the substrate may be may be an adhesive layer, and the adhesive layer formed on the other surface of the substrate may be an adhesive layer other than the adhesive layer (sometimes referred to as a "non-adhesive layer").

As the substrate, paper-based substrates such as paper, fiber-based substrates such as cloth, non-woven fabric, and net; metal-based substrates such as metal foil and metal plate; plastic-based substrates such as plastic films and sheets. An appropriate thin layer body such as a substrate; a rubber-based substrate such as a rubber sheet; can be used. As the substrate, a plastic-based substrate such as a plastic film or sheet can be suitably used. The substrate includes a release liner, and the release liner may be a known release liner for adhesive sheets or tapes.

The optical pressure-sensitive adhesive sheet of the present invention may be formed in a form wound into a roll, or may be formed in a form in which sheets are laminated. That is, the optical pressure-sensitive adhesive sheet of the present invention can have a shape such as a tape shape or a sheet shape. Accordingly, adhesive sheets include adhesive sheets or adhesive tapes.

The method for producing the optical pressure-sensitive adhesive sheet of the present invention is not particularly limited. The pressure-sensitive adhesive sheet for optical use of the present invention can be prepared, for example, by adding a mixture (adhesive composition) of each component such as the pressure-sensitive adhesive of the pressure-sensitive adhesive layer (A) and a diluent added as necessary (adhesive composition) to the support surface (base). material surface, or other adhesive layer surface).

Examples of diluents include, but are not limited to, toluene, benzene, xylene, ethylbenzene, mesitylene, chlorobenzene, nitrobenzene, pentane, hexane, heptane, octane, and dimethyl ether. Among these, toluene is preferred. The diluent may be used singly or in combination of two or more.

When adding a diluent, the mixing ratio is not particularly limited. The blending ratio is such that the solid content concentration of the pressure-sensitive adhesive composition is, for example, 10 to 50% by mass, preferably 25 to 40% by mass, from the viewpoint of coatability and the like.

The method of applying the adhesive composition is not particularly limited. For example, it can be applied using a conventional coater (gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, etc.).

It is preferable to dry after coating. The drying temperature is, for example, 30 to 200°C, preferably 60 to 160°C, more preferably 90 to 130°C. The drying time may vary depending on the drying temperature, but is, for example, 30 seconds to 15 minutes, preferably 2 minutes to 10 minutes, more preferably 3 minutes to 7 minutes.

2. The optical pressure- sensitive adhesive sheet of the present invention including the laminate pressure-sensitive adhesive layer (A) can be used for electric products, electronic products, or optical devices having an optically transparent member, such as mobile phones, smartphones, personal computers, electronic paper, and tablets. When manufacturing image display devices (e.g., liquid crystal displays, OLED displays, electrowetting displays) such as personal computers and game machines, bonding a cover panel and a touch panel module to protect the surface, or bonding the cover panel and the touch panel module together. It can be suitably used for adhering a display panel module or adhering a touch panel module and a display panel module. The optical pressure-sensitive adhesive sheet of the present invention can also be applied to other optical uses such as optical films.

Therefore, as one aspect of the present invention, a laminate (hereinafter referred to as "the present (also referred to as "inventive laminate"), particularly to an optical laminate.

In a preferred embodiment of the present invention, the adherend preferably includes a passivation film, a hard coat layer, a polyvinyl alcohol film, and the like. Since these adherends are materials that easily absorb water, the problem of whitening, which is a problem in the present invention, tends to occur. By using the optical pressure-sensitive adhesive sheet of the present invention, whitening can be effectively suppressed even when such an adherend is employed.

In a preferred embodiment of the present invention, the laminate of the present invention comprises the optical pressure-sensitive adhesive sheet of the present invention and a first cover laminated on the first surface (adhesive layer surface) of the optical pressure-sensitive adhesive sheet of the present invention. It comprises an adherend and a second adherend laminated on the second surface (adhesive layer surface) opposite to the first surface of the optical pressure-sensitive adhesive sheet of the present invention. The first adherend is preferably an antireflection film, an anti-scattering film, a cover panel, a film with a metal or metal oxide thin film, a glass with a metal or metal oxide thin film, a super-birefringent film, or a touch panel module. . The second adherend is preferably a cover panel, a film with a metal or metal oxide thin film, a glass with a metal or metal oxide thin film, a super-birefringent film, a touch panel module, a polarizing plate, or a display panel module.

The cover panel is a cover glass, a polycarbonate plate, or a polymethyl methacrylate plate, and the first adherend is a cover glass, a polycarbonate plate, a polymethyl methacrylate plate, a film with a metal or metal oxide thin film, or a touch panel. Preferably it is a module.

Specific examples of the laminate of the present invention include a cover panel-touch panel module laminate in which a cover panel and a touch panel module are bonded via the optical pressure-sensitive adhesive sheet of the present invention, and a laminate obtained by bonding the cover panel and the touch panel module via the optical pressure-sensitive adhesive sheet of the present invention. A cover panel-display panel module laminate in which a cover panel and a display panel module are adhered, a touch panel module-display panel module laminate in which a touch panel module and a display panel module are adhered via the optical pressure-sensitive adhesive sheet of the present invention, etc. is mentioned. A glass plate is preferably used as the cover panel.

A transparent electrode layer-attached film laminate in which two transparent electrode layer-attached films made of metal or metal oxide are laminated via the optical pressure-sensitive adhesive sheet of the present invention is also preferable as the laminate of the present invention.

The layered product of the present invention is suitably used for an image display device comprising an optical layered product and an image display section.

A preferred embodiment of the laminate of the present invention is a transparent conductive film with a pressure-sensitive adhesive layer having the optical pressure-sensitive adhesive sheet of the present invention. Due to their properties, transparent conductive films are usually used in devices that display images, and in this case, whitening, which is a problem in the present invention, can cause a problem of deterioration in image display quality. In addition, the transparent conductive film may use a material that easily absorbs water such as a hard coat layer, and in this case, the problem of whitening is likely to occur. Therefore, the optical pressure-sensitive adhesive sheet of the present invention, in which the water content (water retention performance under a specific environment) and moisture permeability are adjusted and thereby has excellent whitening resistance, solves these problems in the transparent conductive film. It is possible to contribute to the elimination, and it can be suitably used for the film.

Embodiments of the pressure-sensitive adhesive layer-attached transparent conductive film will be described below with reference to the drawings.

1(a) and 1(b) are cross-sectional views showing an embodiment in which an optical pressure-sensitive adhesive sheet 1 of the present invention is provided on a transparent conductive film 2. FIG. The transparent conductive film 2 shown in FIG. 1(a) has a transparent conductive thin film 3 on one side of a transparent plastic film substrate 4 and a functional layer 5 on the other side. The optical pressure-sensitive adhesive sheet 1 can be formed on the side of the transparent plastic film substrate 4 having the functional layer 5 (that is, the side opposite to the transparent conductive thin film 3). The adhesive surface of the optical adhesive sheet 1 on which the transparent conductive film 2 is not attached may be protected with a release film (not shown) until it is put to practical use. In the transparent conductive film 2 shown in FIG. 1(b), the bonding positions of the transparent conductive thin film 3 and the functional layer 5 shown in FIG. 1(a) are reversed.

The transparent plastic film substrate is not particularly limited, but various transparent plastic films are used. The plastic film is formed of one layer of film. For example, the materials include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and (meth)acrylic resins. , polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, polyphenylene sulfide-based resins, and the like. Among these, polyester-based resins, polyimide-based resins, and polyethersulfone-based resins are particularly preferred. The thickness of the film substrate is preferably 15 to 200 μm.

The surface of the film substrate is preliminarily subjected to sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, etching treatment such as oxidation, and undercoating treatment, and the transparent conductive thin film or undercoat to be provided thereon. You may make it improve the adhesiveness with respect to the said film base material of a coat layer. In addition, before providing the transparent conductive thin film or the undercoat layer, dust removal and cleaning may be performed by solvent cleaning, ultrasonic cleaning, or the like, if necessary.

The constituent material of the transparent conductive thin film is not particularly limited, and is selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, tungsten, and cadmium. A metal oxide of at least one selected metal is used. The metal oxide may further contain the metal atoms shown in the above groups, if necessary. For example, although not particularly limited, ITO (indium tin oxide), ZnO, SnO, CTO (cadmium tin oxide), etc. are preferably used, and ITO is particularly preferably used. ITO preferably contains 80 to 99% by weight of indium oxide and 1 to 20% by weight of tin oxide. The thickness of the transparent conductive thin film is not particularly limited, but is about 10 to 200 nm, more preferably 15 to 40 nm, further preferably 20 to 30 nm from the viewpoint of thin film.

Although not shown in FIG. 1, a transparent conductive thin film can be provided on the transparent plastic film substrate via an undercoat layer. A plurality of undercoat layers can be provided. An oligomer migration prevention layer can be provided between the transparent plastic film substrate and the pressure-sensitive adhesive layer.

The undercoat layer can be formed from an inorganic material, an organic material, or a mixture of an inorganic material and an organic material. For example, inorganic substances include NaF (1.3), Na3AlF6 (1.35), LiF (1.36), MgF2 (1.38), CaF2 (1.4), BaF2 (1.3), SiO2 (1 .46), LaF3 (1.55), CeF3 (1.63), and Al2O3 (1.63) [the numerical value in parentheses of each material is the refractive index of light]. Among these, SiO2, MgF2, A12O3 and the like are preferably used. SiO2 is particularly suitable. In addition to the above, a composite oxide containing about 10 to 40 parts by weight of cerium oxide and about 0 to 20 parts by weight of tin oxide can be used with respect to indium oxide.

Examples of organic materials include acrylic resins, urethane resins, melamine resins, alkyd resins, siloxane-based polymers, organic silane condensates, and the like. At least one of these organic substances is used. In particular, it is desirable to use a thermosetting resin composed of a mixture of a melamine resin, an alkyd resin and an organic silane condensate as the organic substance.

Although the thickness of the undercoat layer is not particularly limited, it is usually about 300 nm or less, preferably about 1 to 300 nm, from the viewpoint of optical design and the effect of preventing oligomer generation from the film substrate. It is preferably about 5 to 300 nm, and more preferably about 5 to 300 nm.

As the functional layer, for example, an antiglare (AG) layer and an antireflection (AR) layer can be provided for the purpose of improving visibility. The constituent material of the antiglare treatment layer is not particularly limited, and for example, an ionizing radiation curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used. The thickness of the antiglare layer is preferably 0.1 to 30 μm. As the antireflection layer, titanium oxide, zirconium oxide, silicon oxide, magnesium fluoride, etc. are used. A plurality of antireflection layers can be provided.

Moreover, a hard coat (HC) layer can be provided as a functional layer. As a material for forming the hard coat layer, for example, a cured film made of a curable resin such as melamine resin, urethane resin, alkyd resin, acrylic resin, silicone resin, etc. is preferably used. The thickness of the hard coat layer is preferably 0.1 to 30 μm. A thickness of 0.1 μm or more is preferable for imparting hardness. Moreover, the antiglare treatment layer and the antireflection layer can be provided on the hard coat layer.

The optical pressure-sensitive adhesive sheet of the present invention is applied to the functional layer or transparent conductive layer of the transparent conductive film to be used as a transparent conductive film with a pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer can be formed on the transparent conductive film by directly applying the pressure-sensitive adhesive layer to the functional layer or the transparent conductive layer of the transparent conductive film and removing the solvent by heat drying or the like. Also, the pressure-sensitive adhesive layer formed on the release-treated separator can be appropriately transferred to the functional layer or transparent conductive layer of the transparent conductive film to form a transparent conductive film with a pressure-sensitive adhesive layer.

The release-treated sheet used in the production of the transparent conductive film with the pressure-sensitive adhesive layer can be used as it is as a separator for the transparent conductive film with the pressure-sensitive adhesive layer, and the process can be simplified.

In forming the pressure-sensitive adhesive layer in the transparent conductive film with the pressure-sensitive adhesive layer, an anchor layer is formed on the surface of the transparent conductive film, or various easy-adhesion treatments such as corona treatment and plasma treatment are performed. After that, the adhesive layer can be formed. In addition, the surface of the pressure-sensitive adhesive layer may be subjected to an easy-adhesion treatment.

The pressure-sensitive adhesive layer-attached transparent conductive film is used in the formation of various devices such as touch panels and liquid crystal displays. In particular, it can be preferably used as an electrode plate for a touch panel. A touch panel is suitably used for various detection methods (for example, a resistive film method, a capacitive method, etc.).

In a capacitive touch panel, a transparent conductive film having a transparent conductive thin film having a predetermined pattern is generally formed over the entire display area.

FIG. 2 shows an example of a capacitive touch panel using the transparent conductive film with an adhesive layer of the present invention. In FIG. 2, 6 is a capacitive touch panel, 7 is a decorative panel, 8 is an adhesive layer or adhesive sheet, 9 is a transparent conductive film, and 10 is a hard coat film. The decorative panel 7 is preferably a glass plate or a transparent acrylic plate (PMMA plate). The hard coat film 10 is preferably a transparent plastic film such as a PET film that has undergone a hard coat treatment.

For example, in FIG. 2, the pressure-sensitive adhesive layer 8 sandwiched between two transparent conductive films 9 corresponds to the optical pressure-sensitive adhesive sheet 1 of the present invention shown in FIG.

Since the optical pressure-sensitive adhesive sheet 1 of the present invention is used, the capacitive touch panel 6 has high sebum resistance and humidity cloudiness resistance, can be made thin, and has excellent operational stability. . In addition, the appearance and visibility are good.

The optical pressure-sensitive adhesive sheet of the present invention can also be used in touch panels having configurations other than those described above. Specifically, transparent substrate (for example, glass, etc.)/adhesive layer (or adhesive sheet)/transparent conductive film/adhesive layer (or adhesive sheet)/transparent conductive film/adhesive layer (or adhesive sheet) / liquid crystal display device (LCD); transparent substrate with transparent conductive thin film such as ITO (e.g., glass) / adhesive layer (or adhesive sheet) / transparent conductive film / adhesive layer (or adhesive sheet) / liquid crystal It can be applied in the configuration of a display device (LCD);

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited by these examples.

(1) Preparation of adhesive sheet
(1-1) Example 1
60 parts by mass of styrene-(ethylene-propylene)-styrene block copolymer (SEPS, trade name: Septon 2063, styrene content: 13% by mass (St13%), manufactured by Kuraray Co., Ltd.) as a styrene-based block copolymer, 13 parts by mass of polyisobutylene (trade name: Nisseki Polybutene HV-300, number average molecular weight: 1400, manufactured by JXTG Nippon Oil & Energy Corporation) as a softening agent, and a styrene-aromatic hydrocarbon copolymer (trade name: 27 parts by mass of FMR0150, softening point: 145° C., manufactured by Mitsui Chemicals, Inc.) was stirred in toluene and uniformly dissolved to obtain an adhesive composition (solid concentration: 35% by mass).

The obtained adhesive composition is applied on the separator 1 (polyethylene terephthalate film with a thickness of 75 μm that has been subjected to release treatment) and dried at 110° C. for 5 minutes to form a coating film with a dry film thickness of 25 μm (adhesive layer ( A)) was formed. A separator 2 (polyethylene terephthalate film having a thickness of 50 μm and having undergone release treatment) was further attached to the surface opposite to the surface of the coating film to which the separator 1 was attached, to obtain an optical pressure-sensitive adhesive sheet.

(1-2) Examples 2 to 14 and Comparative Examples 1 to 3
An optical pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 according to the composition shown in Tables 1 and 2 (the unit of composition is % by mass). Components other than those used in Example 1 are as follows.

(a) Styrene block copolymer (a1) Styrene-(ethylene-propylene)-styrene block copolymer (SEPS, trade name: Septon 2002, styrene content: 30% by mass (St30%), manufactured by Kuraray Co., Ltd. )
(a2) Styrene-(ethylene-butylene)-styrene type block copolymer (SEBS, trade name: Tuftec H1062, styrene content: 18% by mass (St18%), manufactured by Asahi Kasei Corporation)
(a3) Styrene-(ethylene-butylene)-styrene type block copolymer (SEBS, trade name: Tuftec H1041, styrene content: 30% by mass (St30%), manufactured by Asahi Kasei Corporation)
(a4) Acid-modified styrene-(ethylene-butylene)-styrene type block copolymer (SEBS (acid-modified), trade name: Tuftec C5025, acid value: 4 mg CH3ONa/g, styrene content: 12% by mass (St1%) , manufactured by Asahi Kasei Corporation).

(b) Silane coupling agent (b1) 3-glycidoxypropyltrimethoxysilane (trade name: KBM403, manufactured by Shin-Etsu Silicone Co., Ltd.).

(1-3) Examples 15-17
An optical pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 according to the composition shown in Table 2 (the unit of composition is % by mass). Components other than those used in Examples 1 to 14 were prepared as follows.

In an autoclave, 4000 g of cyclohexane, 200 g of 1,3-butadiene monomer, 3.0 g of n-butyllithium and tetrahydrofuran were added at a molar ratio of n-BuLi/THF=40, polymerized at 70° C. for 40 minutes, and then 300 g of styrene monomer. was added for 60 minutes, and then ₅₀₀ g of 1,3-butadiene monomer was added for 150 minutes. This was a styrenic block copolymer with a bound styrene content of 20%. This copolymer was diluted with purified and dried cyclohexane, adjusted to a polymer concentration of 5% by weight, and subjected to a hydrogenation reaction. Into a sufficiently dried autoclave having a capacity of 2 and equipped with a stirrer, 1000 g of the above polymer solution was charged, degassed under reduced pressure, replaced with hydrogen, and maintained at 90° C. with stirring. Next, 50 ml of a cyclohexane solution containing 0.2 mmol of di-p-tolylbis(η-cyclopentadienyl)titanium and 10 ml of a cyclohexane solution containing 0.108 mmol of n-butyllithium were mixed at 0° C. and 2.0 kg/cm2. After mixing under a hydrogen pressure of ² , this was added to the copolymer solution in the autoclave. A hydrogenation reaction was carried out by continuously supplying 5.0 kg/cm ² of dry hydrogen gas for 2 hours while stirring. After returning the reaction solution to normal temperature and normal pressure, 1 ml of methanol was added to deactivate the catalyst. According to ¹ H-NMR analysis, 95% or more of the butadiene units and less than 5% of the styrene units of the obtained polymer were hydrogenated.

(2) Evaluation
(2-1) Moisture Content Optical pressure-sensitive adhesive sheets (Examples 1 to 17 and Comparative Examples 1 to 3) were allowed to stand at 23° C. and 50% RH for 3 days or longer, and then cut into 1.3 cm×4 cm pieces. was peeled off and its mass (α (unit: g)) was measured. An aluminum foil having a thickness of 25 μm was adhered to the surface of the coating film from which the separator 2 had been removed, and the film was allowed to stand at 65° C. and 90% RH for 3 days. When the separator 1 was peeled off and heated at 120 ° C. for 10 minutes using a moisture measuring device (Hiranuma trace moisture measuring device, AQ-2000) and a moisture vaporizing device (Hiranuma moisture vaporizing device, EV-2000) by the Karl Fischer method The amount of water generated (γ (unit: g)) was measured. Further, the separated separator 1 was allowed to stand again at 23° C. and 50% RH for 3 days or more, and the mass (β (unit: g)) was measured.

The water content was calculated from the measured values obtained as described above according to the following formula [water content={γ/(α−β)}×100 (%)]. The results are shown in Tables 1 and 2.

(2-2) Moisture Permeability Measured according to JIS Z 0208 (moisture-proof packaging material moisture permeability test method (cup method)) at a temperature of 65° C. and a humidity of 90% RH. More specifically, the separators 1 and 2 of the optical adhesive sheets (Examples 1 to 17 and Comparative Examples 1 to 3) were peeled off and attached to a metal mesh. A moisture-permeable cup (inner diameter: 60 mm) containing about 10 g of calcium chloride was covered with a single layer sheet for evaluation bonded to a metal mesh to seal the periphery. After that, it was left standing at 60° C. and 90% RH for evaluation. The results are shown in Tables 1 and 2.

(2-3) Whitening (turbidity)
Optical adhesive sheets (Examples 1 to 17 and Comparative Examples 1 to 3) laminated between glass and polyethylene terephthalate film were used as test pieces. was observed under a three-wavelength fluorescent lamp. "○" indicates that there was no difference in turbidity between the edge and the center of the test piece, "△" indicates that the edge of the test piece was slightly cloudy, and the edge of the test piece was completely When the test piece became cloudy and the object could not be visually recognized through the test piece, it was evaluated as "x". The results are shown in Tables 1 and 2.

(2-4) Haze
Optical pressure-sensitive adhesive sheets (Examples 1 to 17 and Comparative Examples 1 to 3) were laminated between glass and polyethylene terephthalate film as test pieces, immersed in water in a 65 ° C. environment, and haze after 240 hours. It was measured. Specifically, an optical pressure-sensitive adhesive sheet is attached to soda glass (0.7 × 56 × 86.6 mm), and a spectrophotometer (Konica Minolta, CM-3700d) is used at room temperature (23 ° C.). Haze was measured when the light transmitted from the single layer sheet surface to the soda glass surface was evaluated by the SCI method. "◎" when the difference in haze between the end and the center of the test piece is less than 0.5, "○" when the difference between the end and the center of the test piece is 0.5 or more and less than 1, A case where the difference in haze between the end portion and the central portion of the test piece was 1 or more and less than 5 was evaluated as "Δ", and a case where the difference in haze between the end portion and the central portion of the test piece was 5 or more was evaluated as "x". The results are shown in Tables 1 and 2.

(2-5) Disappearance of whitening When the evaluation of "(2-3) whitening" is "△" or "×" (when whitening occurs), after standing at 23 ° C. 50% RH for 24 hours , the presence or absence of whitening was observed. A case where the whitening disappeared after standing was evaluated as "○", and a case where whitening was observed even after standing was evaluated as "X". The results are shown in Tables 1 and 2.

REFERENCE SIGNS LIST 1 optical adhesive sheet 2 transparent conductive film 3 transparent conductive thin film 4 transparent plastic film substrate 5 functional layer 6 capacitive touch panel 7 decorative panel 8 optical adhesive sheet 9 transparent conductive film 10 hard coat film 11 ITO layer 12 PET base material layer 13 HC layer 14 glass

Claims (12)

including an adhesive layer (A) containing a styrenic block copolymer,
The styrene content in the styrenic block copolymer is 10 to 30% by mass,
The content of the softening agent in the adhesive layer (A) is 0 to 10% by mass with respect to 100% by mass of the adhesive layer (A),
The adhesive layer (A) has a water content of 0.10 to 0.25% by mass after standing at 65 ° C. 90% RH for 3 days, and the moisture permeability of the adhesive layer (A) at 65 ° C. 90% RH. is 420 to 1000 g/m ² ·day, and
The adhesive layer (A) contains only a styrenic block copolymer as a copolymer,
Optical adhesive sheet. The optical pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer (A) contains a tackifier. The tackifier is a tackifier having a softening point of 85 ° C. or higher and an aromatic ring, and the content of the tackifier in the adhesive layer (A) is 100 mass of the adhesive layer (A) 3. The optical pressure-sensitive adhesive sheet according to claim 2, which is 40% by mass or less based on %. The optical product according to any one of claims 1 to 3, wherein the content of the styrene-based block copolymer in the adhesive layer (A) is 45 to 85% by mass with respect to 100% by mass of the adhesive layer (A). Adhesive sheet for The optical pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , comprising only the pressure-sensitive adhesive layer (A) as the pressure-sensitive adhesive layer. A laminate comprising the optical pressure-sensitive adhesive sheet according to any one of claims 1 to 5 and an adherend disposed on the optical pressure-sensitive adhesive sheet. The optical pressure-sensitive adhesive sheet according to any one of claims 1 to 5 , a first adherend laminated on the first surface of the optical pressure-sensitive adhesive sheet, and the first surface of the optical pressure-sensitive adhesive sheet. 7. The laminate of claim 6 , comprising a second adherend laminated to a second surface opposite the second adherend. The first adherend is an antireflection film, a shatterproof film, a cover panel, a film with a metal or metal oxide thin film, a glass with a metal or metal oxide thin film, a superbirefringent film, or a touch panel module, and 8. The second adherend is a cover panel, a film with a metal or metal oxide thin film, a glass with a metal or metal oxide thin film, a super-birefringent film, a touch panel module, a polarizing plate, or a display panel module. The laminate according to . A transparent conductive film having a transparent conductive thin film formed of a metal oxide on one side of a transparent plastic film substrate and a functional layer on the other side, wherein the transparent conductive film of claims 1 to 5 is provided on one side A transparent conductive film with an adhesive layer comprising the optical adhesive sheet according to any one of the above. 10. The transparent conductive film with a pressure-sensitive adhesive layer according to claim 9 , wherein the optical pressure-sensitive adhesive sheet is provided on the transparent conductive thin film of the transparent conductive film. 11. The transparent conductive film with a pressure-sensitive adhesive layer according to claim 10 , further comprising the optical pressure-sensitive adhesive sheet on the functional layer of the transparent conductive film. A touch panel comprising at least one adhesive layer-attached transparent conductive film according to any one of claims 9 to 11 .