JP6268025B2 - Adhesive sheet - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, and specifically relates to a pressure-sensitive adhesive sheet having a polyester film as a base film.

  Conventionally, a transparent conductive film provided with a transparent electrode layer such as an ITO (Indium Tin Oxide) film is used in a touch panel manufacturing process. This transparent conductive film is provided with a hard coat layer on each of a pair of main surfaces of a support, a transparent electrode layer on one hard coat layer, and an adhesive as a surface protective film on the other hard coat layer. Manufactured by releasably laminating sheets. As a pressure-sensitive adhesive sheet used for the production of a transparent conductive film, a sheet in which a pressure-sensitive adhesive layer is provided on a base film made of a heat-resistant polyester film has been proposed (for example, see Patent Document 1).

  In the touch panel manufacturing process, a transparent conductive film is attached to a glass substrate or the like via an optical adhesive film (hereinafter sometimes referred to as “OCA”). A release film made of a polyester film is usually laminated on both sides of the OCA.

JP 2003-205567 A

  By the way, in the manufacturing process of the transparent conductive film used for a touch panel, the protective sheet which uses a polyester film as a base film is used. However, when a transparent conductive film is manufactured using a polyester film, oligomers such as monomers, dimers, and trimers may leak to the surface of the protective sheet when the protective sheet is heated during annealing of the transparent electrode layer. . When the transparent conductive film is rolled up together with the protective sheet in a state where the oligomer is deposited on the surface of the protective sheet, the oligomer may adhere to the surface of the transparent electrode layer and the transparent electrode layer may be contaminated or damaged.

  This invention is made | formed in view of such a situation, and it aims at providing the adhesive sheet provided with the release film which can reduce the malfunction based on the leakage of an oligomer, even if it passes through a heating process.

  The pressure-sensitive adhesive sheet of the present invention is provided on a first base film made of a polyester film, a resin layer provided on one surface of the first base film, and on the other surface of the first base film. A release film having a release layer formed thereon and a pressure-sensitive adhesive layer provided on the surface of the release layer, wherein the resin layer is (A) 50% by mass to 80% by mass of bisphenol. A resin composition containing an A-type epoxy compound, (B) 5% by mass to 30% by mass of a polyester compound, and (C) 10% by mass to 40% by mass of a polyfunctional amino compound is cured. Features.

  According to this configuration, since the resin composition including the bisphenol A type epoxy resin compound, the polyester compound, and the polyfunctional amino compound is cured and the resin layer is provided on one surface of the first base film, the resin layer is crosslinked. The density is in an appropriate range. Thereby, the pressure-sensitive adhesive sheet can prevent precipitation of oligomers on the surface side of the pressure-sensitive adhesive sheet from the polyester film, and also prevents the occurrence of cracks in the resin layer even when pressure or impact is applied to the pressure-sensitive adhesive sheet. It is possible to prevent the oligomer from leaking from the crack. Furthermore, since the release film also has a function as a protective sheet opposite to the outer surface such as a functional layer provided on the pressure-sensitive adhesive layer, the production cost of the functional film can be reduced.

  In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer is provided on a core material layer, a first pressure-sensitive adhesive layer provided on one surface of the core material layer, and the other surface of the core material layer. It is preferable that the 2nd adhesive layer obtained was included.

  In the adhesive sheet of this invention, it is preferable to provide the 2nd base film further provided on the said adhesive layer.

  The pressure-sensitive adhesive sheet of the present invention preferably further comprises a functional layer provided on the second base film.

  In the pressure-sensitive adhesive sheet of the present invention, the functional layer is preferably a transparent conductive layer.

  In the pressure-sensitive adhesive sheet of the present invention, the release layer is preferably formed by curing an addition reaction type silicone.

  In the pressure-sensitive adhesive sheet of the present invention, the bisphenol A-type epoxy compound preferably has a mass average molecular weight of 10,000 or more and 50,000 or less.

  In the adhesive sheet of this invention, it is preferable that the glass transition temperature (Tg) of the said polyester compound is 0 degreeC or more and 50 degrees C or less.

  In the pressure-sensitive adhesive sheet of the present invention, it is preferable that the resin layer is a cured film obtained by heating a coating layer formed by coating the solution of the resin composition on the first base film.

  In the adhesive sheet of this invention, it is preferable that the film thickness of the said resin layer is 50 nm or more and 500 nm or less.

  ADVANTAGE OF THE INVENTION According to this invention, even if it passes through a heating process, it can implement | achieve providing the adhesive sheet provided with the release film which can reduce the malfunction based on the leakage of an oligomer.

FIG. 1 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the second embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the third embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to the fourth embodiment of the present invention. FIG. 5 is an explanatory diagram of a transparent conductive film using the pressure-sensitive adhesive sheet according to the embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited to the following embodiment, It can implement by changing suitably. Further, the following embodiments can be implemented in combination as appropriate. Moreover, the same code | symbol is attached | subjected to the component which is common in the following embodiment, and duplication of description is avoided.

  FIG. 1 is a schematic cross-sectional view of an adhesive sheet 1 according to the first embodiment of the present invention. As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to the present embodiment is provided with a base film (first base film) 11 made of a polyester film, and on one surface of the base film 11. A first release having a resin layer 12 formed by curing the layer forming composition and a release layer 13 provided on the other surface of the base film 11 and formed by curing the release layer forming composition. A mold film 10 and an adhesive layer 14 provided on the surface of the release layer 13 are provided. That is, in the pressure-sensitive adhesive sheet 1, the resin layer 12, the base film 11, the release layer 13, and the pressure-sensitive adhesive layer 14 are laminated in this order.

  The 2nd release film 21 is stuck on the opposite surface of the 1st release film 10 of the adhesive layer 14 so that peeling is possible. The pressure-sensitive adhesive sheet 1 is a laminate in which the second release film 21 is laminated on the pressure-sensitive adhesive layer 14, wound around a core material in a roll shape, and stored. Then, the laminated body of the roll-shaped pressure-sensitive adhesive sheet 1 and the second release film 21 is unwound, the second release film 21 is removed from the pressure-sensitive adhesive sheet 1, and the first cover is exposed on the surface of the pressure-sensitive adhesive layer 14. Affix to the body. Subsequently, the first release film 10 is removed, and the exposed surface of the pressure-sensitive adhesive layer 14 is attached to the second adherend. In this process, in a stage where the first adherend is laminated with the first release film 10 via the pressure-sensitive adhesive layer 14, a predetermined heat treatment is performed to manufacture a desired product. Is possible. The first adherend includes a transparent conductive film (or a raw material film thereof), the second adherend includes a glass substrate, and the predetermined heat treatment includes crystallization of the transparent conductive material. However, the present invention is not limited to this. By setting the pressure-sensitive adhesive sheet 1 to such a configuration, the first adherend is prevented from being contaminated or damaged by the oligomer even though a polyester film is used as the first base film 11. .

  In the pressure-sensitive adhesive sheet 1 according to the present embodiment, the resin layer 12 provided on one surface of the base film 11 is (A) 50% by mass to 80% by mass of a bisphenol A type epoxy compound, (B) It is provided by curing a resin composition containing 5% by mass to 30% by mass of a polyester compound and (C) 10% by mass to 40% by mass of a polyfunctional amino compound. Thereby, since the resin layer 12 becomes a crosslinking density which can prevent permeation | transmission of oligomers, such as a monomer, a dimer, and a trimer which remain | survive in the polyester film which comprises the base film 11, to one surface of the adhesive sheet 1 The bleed-out of the oligomer can be prevented. As a result, the pressure-sensitive adhesive sheet 1 has an Δhaze value that is an absolute value of a difference between an initial haze value and a post-heating haze value after the pressure-sensitive adhesive sheet 1 is heated at 150 ° C. for 2 hours to 0.15% or less. It becomes possible. In addition, since the resin layer 12 has a cross-linking density that provides appropriate flexibility, when the pressure-sensitive adhesive sheet 1 is wound around the core material with the second release film 21 fixed on the pressure-sensitive adhesive layer 14, Even if pressure or impact is applied, it is possible to prevent the resin layer 12 from being cracked. Furthermore, since the 1st release film 10 can also play the role of the protective sheet affixed on the opposite surface to the outer surface of the 1st to-be-adhered body provided on the adhesive layer 14, reduction of the manufacturing cost of a product Is possible.

  FIG. 2 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet 2 according to the second embodiment of the present invention. As shown in FIG. 2, the pressure-sensitive adhesive sheet 2 includes a core material 141 and a first surface provided on one surface of the core material 141 as the pressure-sensitive adhesive layer 14 of the pressure-sensitive adhesive sheet 1 according to the first embodiment. 1 adhesive layer 142 and the 2nd adhesive layer 143 provided on the other surface of the core material 141 are included. That is, in the pressure-sensitive adhesive sheet 2, the first pressure-sensitive adhesive layer 142, the core material 141 and the second pressure-sensitive adhesive layer 143 are laminated on the surface of the release layer 13, and the second pressure-sensitive adhesive layer 142 has a first Two release films 21 are laminated. As the core material 141, for example, various films such as a polyester film similar to the base film 11, paper, non-woven fabric, and the like can be used. The pressure-sensitive adhesive layer 14, the first pressure-sensitive adhesive layer 142, and the second pressure-sensitive adhesive layer 143 are made of the same material. Furthermore, since the 1st release film 10 can also play the role of the protective sheet affixed on the opposite surface to the outer surface of the 1st to-be-adhered body provided on the adhesive layer 14, reduction of the manufacturing cost of a product Is possible.

  FIG. 3 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet 3 according to the third embodiment of the present invention. As shown in FIG. 3, the pressure-sensitive adhesive sheet 3 is a base film (second base film) on the pressure-sensitive adhesive layer 14 instead of the second release film 21 of the pressure-sensitive adhesive sheet 1 according to the first embodiment. 22 is laminated so as not to be peeled off. The pressure-sensitive adhesive sheet 3 can be used as a substrate on which a functional layer such as a transparent conductive film is provided on the base film 22. In this pressure-sensitive adhesive sheet 3, since the resin layer 12 can prevent oligomers from being deposited on the surface of the pressure-sensitive adhesive sheet 3, after the heat-treated pressure-sensitive adhesive sheet 3, the core material is wound into a roll. In addition, it becomes possible to prevent contamination and damage of the outer surface of the base film 22 based on the bleed out of the oligomer inside the base film 11. Furthermore, since the 1st release film 10 can also play the role of the protective sheet affixed on the opposite surface to the outer surface of the base film 22, the manufacturing cost of a product can be reduced.

  FIG. 4 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet 4 according to the fourth embodiment of the present invention. As shown in FIG. 4, this adhesive sheet 4 is obtained by laminating a functional layer 23 on the adhesive sheet 3 according to the third embodiment. Examples of the functional layer 23 include, but are not limited to, a transparent conductive film that constitutes a transparent conductive layer. This adhesive sheet 4 is used for manufacture of the transparent conductive film used for a touch panel etc., for example. The pressure-sensitive adhesive sheet 4 is manufactured by forming the functional layer 23 on the base film 22 of the pressure-sensitive adhesive sheet 3 according to the above-described third embodiment, and heats the pressure-sensitive adhesive sheet 4 on which the functional layer 23 is formed. The transparent conductive film can be manufactured by annealing. And since the resin layer 12 is provided in the back surface side (one surface side of the adhesive sheet 4) of the functional layer 23, precipitation of the oligomer to the one surface side of the adhesive sheet 4 can be prevented. Therefore, even when the functional layer 23 is formed and wound around the core material in a roll shape, contamination and damage of the surface of the functional layer 23 can be prevented. Furthermore, since the 1st release film 10 can also play the role of the protective sheet stuck on the back surface of the transparent conductive film in a prior art, it becomes possible to reduce the manufacturing cost of a transparent conductive film. Hereinafter, various components constituting the pressure-sensitive adhesive sheets 1 to 4 according to the present embodiment will be described.

(Base film 11)
As the base film (first base film) 11, various polyester films can be used within a range where the effects of the present invention are exhibited. The polyester film is excellent in heat resistance, and does not cause defects such as shrinkage and melting even when a transparent electrode layer such as a transparent conductive film is annealed at a high temperature. As the polyester film, for example, polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate are preferable. Moreover, as a polyester film, a biaxially stretched polyethylene terephthalate film is more preferable.

  The thickness of the base film 11 can be appropriately changed according to the application. The thickness of the base film 11 is preferably 10 μm or more, preferably 20 μm or more, from the viewpoint of maintaining the strength of the pressure-sensitive adhesive sheet and ensuring flexibility during the production of a transparent conductive film by a roll-to-roll method. Is more preferably 30 μm or more, more preferably 250 μm or less, more preferably 225 μm or less, and further preferably 200 μm or less. Considering the above, the thickness of the base film 11 is preferably 10 μm or more and 250 μm or less, more preferably 20 μm or more and 225 μm or less, and further preferably 30 μm or more and 200 μm or less.

(Base film 22)
As the 2nd base film 22, what has heat resistance from a plastic film can be selected suitably, and can be used. Examples of such plastic films include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate (PEN), polyethylene films, polypropylene films, cellophane, diacetyl cellulose films, triacetyl cellulose films, and acetyl cellulose. Butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether ether ketone film, polyether sulfone Film, polyetherimide film, polyimide film, Fluororesin film, a polyamide film, may be used an acrylic resin film, norbornene resin film, and a plastic film such as a cycloolefin resin film. Among these, a polyester film, a polycarbonate film, a polyimide film, a norbornene resin film, a cycloolefin resin film, and the like are preferable from the viewpoint of being suitably used as an optical substrate and having excellent transparency. More preferably.

  As the 2nd base film 22, the layer which adds a various function to the surface of the above-mentioned plastic film may be provided. For example, the surface on the side in contact with the pressure-sensitive adhesive layer 14 may have an easy-adhesion layer for strengthening the close contact with the pressure-sensitive adhesive layer 14, and the hard coat layer is provided on the surface opposite to the pressure-sensitive adhesive layer 14. It may be provided.

  As thickness of the 2nd substrate film 22, 25 micrometers or more are preferred, 30 micrometers or more are more preferred, 35 micrometers or more are still more preferred, 250 micrometers or less are preferred, 225 micrometers or less are more preferred, and 200 micrometers or less are still more preferred. Considering the above, the thickness of the second base film 22 is preferably 25 μm or more and 250 μm or less, more preferably 30 μm or more and 225 μm or less, and further preferably 35 μm or more and 200 μm or less.

(Resin layer 12)
The resin layer 12 is (A) 50% by mass or more, preferably 60% by mass or more, and 80% by mass or less, preferably 70% by mass or less bisphenol A type epoxy compound (hereinafter also simply referred to as “component (A)”). ), (B) 5% by mass or more, preferably 10% by mass or more, and 30% by mass or less, preferably 20% by mass or less of a polyester compound (hereinafter also simply referred to as “component (B)”), (C And 10% by mass or more, preferably 20% by mass or more, and 40% by mass or less, preferably 30% by mass or less of a polyfunctional amino compound (hereinafter also simply referred to as “component (C)”). It is the cured film which hardened the resin composition for use. Hereinafter, each component which comprises a resin composition is demonstrated in detail.

<(A) Bisphenol A type epoxy compound>
(A) As a bisphenol A type epoxy compound, the bisphenol A type epoxy resin etc. which are the copolymers of bisphenol A and epichlorohydrin are mentioned, for example.

  The component (A) preferably has a mass average molecular weight (Mw) of 10,000 or more and 50,000 or less from the viewpoint of obtaining a cured film having an appropriate crosslinking density. When the mass average molecular weight (Mw) of the component (A) is 10,000 or more, it is possible to obtain a sufficient crosslinking density as a cured film and sufficiently prevent oligomer precipitation. Moreover, if the mass average molecular weight (Mw) of (A) component is 50000 or less, a moderate softness | flexibility can be provided to a cured film and the crack of the resin layer 12 at the time of deforming the adhesive sheet 1 will be prevented. be able to.

<(B) Polyester compound>
(B) As a polyester compound, various well-known polyester compounds can be used in the range with the effect of this invention. Examples of the polyester compound include a resin obtained by a condensation reaction between a polyhydric alcohol and a polybasic acid. Examples of such a resin include a condensate of a dibasic acid and a dihydric alcohol or an invertible polyester compound obtained by modifying the condensate with a non-drying oil fatty acid, and a condensate of a dibasic acid and a trihydric or higher alcohol. And a convertible polyester compound. A polyester compound may be used individually by 1 type, and may use 2 or more types together.

  Examples of the polyhydric alcohol include dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, and neopentyl glycol, glycerin, trimethylolethane, and trimethylolpropane. Examples thereof include tetrahydric or higher polyhydric alcohols such as trihydric alcohol, diglycerin, triglycerin, pentaerythritol, dipentaerythritol, mannitol, and sorbit. These polyhydric alcohols may be used alone or in combination of two or more.

  Examples of the polybasic acid include aromatic polybasic acids such as phthalic anhydride, terephthalic acid, isophthalic acid, and trimetic anhydride, aliphatic saturated polybasic acids such as succinic acid, adipic acid, and sebacic acid, and maleic acid. Aliphatic unsaturated polybasic acids such as maleic anhydride, fumaric acid, itaconic acid, and citraconic anhydride, cyclopentadiene-maleic anhydride adduct, terpene-maleic anhydride adduct, and rosin-maleic anhydride adduct And polybasic acid obtained by Diels-Alder reaction. These polybasic acids may be used individually by 1 type, and may use 2 or more types together.

  (B) As a polyester compound, what has active hydrogen groups, such as a hydroxyl group, a carboxyl group, and an amino group used as the reaction point of a crosslinking reaction, is preferable, and it is more preferable that it has a hydroxyl group. (B) The polyester compound preferably has a hydroxyl value of 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, preferably 500 mgKOH / g or less, and 300 mgKOH / g or less. More preferred.

  (B) The polyester compound preferably has a number average molecular weight (Mn) of 500 or more, more preferably 1000 or more, and 10,000 from the viewpoint of imparting appropriate flexibility to the resin layer 12. Or less, more preferably 5000 or less. The polyester compound (B) has a glass transition temperature Tg of preferably 0 ° C. or higher, preferably 10 ° C. or higher, and 50 ° C. from the viewpoint of imparting appropriate flexibility to the resin layer 12. Or less, more preferably 40 ° C. or less. By using such a polyester compound (B), it is possible to impart appropriate flexibility to the cured film of the resin layer 12 and prevent cracking of the resin layer 12 even when the pressure-sensitive adhesive sheet 1 is subjected to pressure or impact. And the leakage of oligomers due to cracks can be prevented.

  The amount of component (B) in the resin composition is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 50 parts by mass or less, relative to 100 parts by mass of component (A), and 45 parts by mass. The following is more preferable.

<(C) Polyfunctional amino compound>
(C) Examples of polyfunctional amino compounds include hexamethoxymethyl melamine, methylated melamine compounds, and melamine compounds such as butylated melamine compounds, urea compounds such as methylated urea compounds and butylated urea compounds, and methylated benzoguanamines. Examples thereof include resins and diamines such as benzoguanamine compounds such as butylated benzoguanamine compounds, ethylenediamine, tetramethylenediamine, hexamethylenediamine, N, N′-diphenylethylenediamine, and p-xylylenediamine. Among these, hexamethoxymethylmelamine is preferable from the viewpoint of curability.

  The amount of component (C) in the resin composition is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and preferably 60 parts by mass or less, and 55 parts by mass with respect to 100 parts by mass of component (A). The following is more preferable.

<(D) Acidic catalyst>
The resin composition contains a known acidic catalyst (D) such as hydrochloric acid or p-toluenesulfonic acid (hereinafter, also simply referred to as “component (D)”) as necessary in order to accelerate the curing reaction. May be used. When (D) component is mix | blended, it is preferable that content of (D) component shall be 1 mass% or more and 5 mass% or less with respect to the total mass of a resin composition.

  The resin layer 12 is formed by applying a solution obtained by dissolving the resin composition in an organic solvent on the base film 11 to form an application layer, and the formed application layer is at a temperature of 100 ° C. to 170 ° C. for 5 seconds to 5 seconds. It can be obtained by heat-curing for less than a minute.

  The organic solvent is not particularly limited as long as it can dissolve the resin composition. Examples of the organic solvent include aromatic solvents such as benzene, toluene and xylene, aliphatic solvents such as normal hexane and normal heptane, ester solvents such as ethyl acetate and butyl acetate, methyl ethyl ketone and methyl isobutyl ketone. And ketone solvents such as cyclohexanone and cyclopentanone, and alcohol solvents such as isopropyl alcohol and methanol.

  The film thickness of the resin layer 12 is preferably 50 nm or more, more preferably 80 nm or more, further preferably 100 nm or more, more preferably 500 nm or less, more preferably 300 nm or less, more preferably 250 nm or less, from the viewpoint of effectively suppressing oligomer precipitation. Is more preferable. If the thickness of the resin layer 12 is 50 nm or more, oligomer precipitation can be sufficiently suppressed, and if it is 500 nm or less, the resin layer when the resin layer 12 is formed on the base film 11 by coating. Curling due to cure shrinkage accompanying the crosslinking of 12 can be prevented. Considering the above, the thickness of the resin layer 12 is preferably 50 nm to 500 nm, more preferably 80 nm to 300 nm, and still more preferably 100 nm to 250 nm.

(Release layer 13)
The release layer 13 is formed of, for example, a cured product of a release layer forming composition containing a release agent. The release agent is not particularly limited as long as it can provide the release layer 13 with a function of peeling the pressure-sensitive adhesive layer 14 laminated on the release layer 13 from the first release film 10. Examples of the release agent include silicone resins, long chain alkyl resins, and alkyd resins.

  Examples of the silicone release agent include addition reaction type silicone, condensation reaction type silicone, and energy ray curable type silicone. In order to adjust the peeling force, non-functional polydimethylsiloxane, phenyl-modified silicone, silicone resin, silica, or cellulose compound may be used as an additive.

  The thickness of the release layer 13 is preferably 30 nm or more, preferably 50 nm or more, more preferably 70 nm or more, preferably 500 nm or less, more preferably 400 nm or less, and still more preferably 300 nm or less. If the thickness of the release layer 13 is in such a range, it is easy to obtain a uniform release performance between the first release film 10 and the pressure-sensitive adhesive layer 14, and the first release film 10 is rolled. It is possible to prevent blocking of the surfaces of the first release film 10 that are in contact with each other when wound into a shape.

  The release layer 13 is, for example, coated with a resin composition for forming a release layer on one surface of the base film 11 by a conventionally known coating method, and then heated and dried and cured at a predetermined temperature. By forming. Here, the release layer-forming composition may be coated on the base film 11 after being diluted with an organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene, fatty acid esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aliphatic hydrocarbons such as hexane and heptane.

  Examples of the coating method of the resin composition for forming the release layer include a gravure coating method, a bar coating method, a spray coating method, a spin coating method, an air knife coating method, a roll coating method, a blade coating method, and a gate roll coating. Method, die coating method and the like. Among these, the gravure coating method and the bar coating method are preferable, and the bar coating method is more preferable. Moreover, as a heating / drying method of the resin composition for mold release layer formation, the method of heat-drying with a hot air drying furnace etc. is mentioned, for example. The drying temperature is, for example, 50 ° C. or higher and 150 ° C. or lower. Moreover, it is preferable that drying time is 10 second-5 minutes, for example.

(Adhesive layer 14)
The pressure-sensitive adhesive layer 14 is a conventionally known adhesive such as an acrylic pressure-sensitive adhesive, natural rubber-based pressure-sensitive adhesive, synthetic rubber-based pressure-sensitive adhesive, polyether-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, and urethane acrylate-based pressure-sensitive adhesive. It is formed using an adhesive composition. The pressure-sensitive adhesive is supplied in a form such as a solvent type, an emulsion type, a hot melt solventless type, and an ultraviolet curable solventless type, and the pressure-sensitive adhesive layer 14 is formed by a coating method suitable for each form.

  As an acrylic adhesive, the adhesive composition containing an acrylic polymer is mentioned, for example. The acrylic polymer is obtained by synthesizing a monomer including a (meth) acrylic acid ester, a vinyl monomer containing a reactive group such as a hydroxyl group and a carboxyl group, and the like.

  Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid-n-propyl, (meth) acrylic acid isopropyl, and (meth) acrylic acid-n-. Butyl, (meth) acrylate isobutyl, (meth) acrylic acid-sec-butyl, (meth) acrylic acid-t-butyl, (meth) acrylic acid-n-pentyl, (meth) acrylic acid-n-hexyl, ( (Meth) acrylic acid cyclohexyl, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid isooctyl, (meth) acrylic acid decyl, (meth) acrylic acid dodecyl, (meth) acrylic acid myristyl, (meth) acrylic acid palmityl And the alkyl group in the ester moiety such as stearyl (meth) acrylate has 1 to 20 carbon atoms. (Meth) acrylic acid alkyl ester. Here, “(meth) acryl” represents “acryl” or “methacryl”. These acrylic monomers may be used individually by 1 type, and may use 2 or more types together.

  Examples of vinyl monomers containing reactive functional groups include hydroxyl-containing (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; 1,4-di (meth) ) Acryloxyethyl pyromellitic acid, 4- (meth) acryloxyethyl trimellitic acid, N- (meth) acryloyl-p-aminobenzoic acid, 2- (meth) acryloyloxybenzoic acid, N- (meth) acryloyl- Carboxyl group-containing (meth) acrylates such as 5-aminosalicylic acid, acrylic acid and methacrylic acid; aminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, aminopropyl (meth) acrylate, ethylaminopropyl (meth) acrylate, etc. The first Grade and secondary amino group-containing (meth) acrylate; and 2- (methylthio) thiol group-containing (meth) acrylates such as methacrylate. These may be used alone or in combination of two or more.

  The content of the structural unit derived from the vinyl monomer containing a reactive functional group in the acrylic polymer is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, and 20 mol%. Or less, more preferably 10 mol% or less.

  As an adhesive composition, what contains a crosslinking agent (curing agent) is preferable. The crosslinking agent is preferably at least one selected from the group consisting of polyfunctional isocyanate compounds such as polyfunctional amino compounds and polyisocyanate compounds, polyfunctional epoxy compounds, polyfunctional aziridine compounds, polyfunctional oxazoline compounds and polyfunctional metal compounds. . As a crosslinking agent, what crosslinks an adhesive by reacting with the reactive functional group of an acrylic polymer can be used, for example. Moreover, as an adhesive composition, what contains a hardening accelerator, a hardening retarder, etc. can also be used.

  As a compounding quantity of a crosslinking agent, 0.1 mass part or more is preferable with respect to 100 mass parts of acrylic polymers from a viewpoint which can form the adhesive layer excellent in adhesive performance and cohesion force, 1 mass part The above is more preferable, 30 parts by mass or less is preferable, and 20 parts by mass or less is more preferable.

  The core material 141 can be appropriately selected from known plastic films, paper, and non-woven fabrics, and the plastic film exemplified as the base film 22 is preferably selected.

  The thickness of the pressure-sensitive adhesive layer 14 is not particularly limited as long as it exhibits the effects of the present invention. For example, the thickness is preferably 3 μm or more, more preferably 10 μm or more, further preferably 20 μm or more, and preferably 500 μm or less, 400 μm. The following is more preferable, and 300 μm or less is further preferable.

  Moreover, when the adhesive layer 14 is comprised with the 1st adhesive layer 142, the 2nd adhesive layer 143, and the core material 141, 2 micrometers or more are preferable and, as for the thickness of the core material 141, 5 micrometers or more are more preferable. Moreover, 50 micrometers or less are preferable and 45 micrometers or less are more preferable. The thicknesses of the first pressure-sensitive adhesive layer 142 and the second pressure-sensitive adhesive layer 143 are each preferably 1 μm or more, and more preferably 50 μm or less.

<Second release film 21>
In the pressure-sensitive adhesive sheet 1 according to the present embodiment, the second release film 21 is provided on the outer surface of the pressure-sensitive adhesive layer 14 so that the pressure-sensitive adhesive layer 14 is adhered when the pressure-sensitive adhesive sheet 1 is stored (when not in use). The surface can be protected.

  As the second release film 21, for example, a polyester film such as polyethylene terephthalate, a synthetic resin film such as a polyolefin film such as polyethylene and polypropylene, and the like can be used. Moreover, as the 2nd mold release film 21, what peeled with the silicone resin, the alkyd resin, the long-chain alkyl group containing resin, etc. can also be used for the single side | surface or both surfaces as needed.

  As thickness of a peeling sheet, 10 micrometers or more are preferable, for example, 15 micrometers or more are more preferable, 200 micrometers or less are preferable, and 100 micrometers or less are more preferable.

  In addition, in FIG. 1, although the 2nd release film 21 was shown as a single layer, the 2nd release film 21 is not necessarily limited to what is comprised by a single layer. The second release film 21 may be configured as, for example, a two-layer film in which a base film and a release layer are laminated, or may be configured as a three-layer film like the first release film 10. It may be.

<Functional layer 23>
As the functional layer, for example, a transparent conductive film can be used. As the transparent conductive film, any material having both transparency and conductivity can be used without particular limitation. Examples of the transparent conductive film include thin films such as indium oxide, zinc oxide, tin oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. It is done. These compound thin films become transparent conductive films having both transparency and conductivity depending on the film formation conditions.

  The thickness of the transparent conductive film is preferably 4 nm or more, more preferably 5 nm or more, further preferably 10 nm or more, from the viewpoint of obtaining a continuous thin film and obtaining stable conductivity and sufficient transparency. 800 nm or less is preferable, 500 nm or less is more preferable, and 100 nm or less is particularly preferable.

<Oligomer sealing>
In the prior art, the inventors have focused on the ability to quantitatively evaluate the degree of oligomer precipitation by measuring the haze value of the pressure-sensitive adhesive sheet for the evaluation of oligomer precipitation, which was only visual appearance evaluation. And the present inventors discovered that damage of a transparent electrode layer and foreign material mixing could be prevented effectively by quantitative evaluation of oligomer precipitation by measuring the haze value of an adhesive sheet.

  In the pressure-sensitive adhesive sheet 1 according to the present embodiment, oligomers deposited on the surface layer of the first release film 10 cloud the base film 11 (polyester film) and change the haze value of the pressure-sensitive adhesive sheet 1. Therefore, in the present embodiment, a Δhaze value that is an absolute value of a difference between the initial haze value of the pressure-sensitive adhesive sheet 1 and the post-heating haze value after the pressure-sensitive adhesive sheet 1 is heated at 150 ° C. for 2 hours is measured. Thus, the oligomer sealing property in the resin layer 12 can be confirmed. However, in order to eliminate the influence of the second release film 21 removed at the time of heating use (during annealing treatment), the measurement of the initial haze value and the haze value after heating is performed by removing the second release film 21. It is measured in the state of a laminate of 1 release film 10 and pressure-sensitive adhesive layer 14.

  In this Embodiment, since the resin layer 12 is formed using the said resin composition, since the composition of (A)-(C) component becomes an appropriate range in order to prevent oligomer precipitation from the base film 11, it becomes. , Δhaze value can be 0.15% or less. In addition, the initial haze value of the adhesive sheet 1 is a haze value before the adhesive sheet 1 is heated at 150 ° C. for 2 hours. The Δhaze value is preferably 0.1% or less, more preferably 0.08% or less, and still more preferably 0.04% or less.

  In the present embodiment, the Δhaze value can be calculated as follows. First, the initial haze value (%) of the pressure-sensitive adhesive sheet 1 is measured according to JIS K7105 using a haze meter (trade name: NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) (N = 5 average value). Next, the pressure-sensitive adhesive sheet 1 is suspended in a dryer at 150 ° C., heated for 2 hours, and then the haze value (%) after heating is measured according to JIS K7105 (average value of N = 5). Then, the absolute value of the value obtained by subtracting the initial haze value from the haze value after heating is taken as the Δhaze value.

<Application>
The pressure-sensitive adhesive sheet 1 according to the present embodiment can be used, for example, as an optical pressure-sensitive adhesive (OCA) for bonding a transparent conductive film to a glass substrate or the like in a capacitive touch panel manufacturing process. In particular, the transparent conductive film is bonded before the annealing treatment, and in the annealing treatment, the first release film 10 in the pressure-sensitive adhesive sheet 1 also serves as a protective sheet, and a temperature of about 150 ° C. at which oligomer precipitation becomes a problem. It can also be suitably used for the annealing process. In addition, the adhesive sheet 1 which concerns on this Embodiment is applicable also in the use which requires heat processing other than the manufacturing process of the touch panel which uses a transparent conductive film.

  FIG. 5 is an explanatory diagram of the transparent conductive film 5 using the pressure-sensitive adhesive sheet 1 according to the present embodiment. As shown in FIG. 5, in the transparent conductive film 5, a hard coat layer 52b is provided on one surface of a support 51, and a transparent conductive layer 53 (transparent conductive film: indium tin oxide) is formed on the hard coat layer 52b. Film) is provided by sputtering, CVD, PVD or the like. A hard coat layer 52 a is provided on the other surface of the support 51, and the adhesive sheet 1 is laminated on the hard coat layer 52 a with the adhesive layer 14 interposed therebetween. As described above, when the annealing process is performed in a state where the pressure-sensitive adhesive sheet 1 is provided on the transparent conductive film 5, the crystallization of ITO proceeds and the low-resistance transparent electrode layer 53 is created.

  Here, by using the pressure-sensitive adhesive sheet of the present embodiment, oligomers contained in the polyester film of the base film 11 bleed out or oligomers on the surface of the resin layer 12 even in annealing treatment and other heat treatments. Since precipitation of the crystal derived from origin can be suppressed suitably, mixing of the fine foreign material derived from an oligomer unfavorable as a touch panel and damage to a transparent electrode layer can be suppressed.

  Hereinafter, the present invention will be described in more detail based on examples made to clarify the effects of the present invention. In addition, this invention is not limited at all by the following examples and comparative examples.

<Calculation of Δhaze value>
Each of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples was cut into 5 cm squares, and a test piece was prepared by peeling the second release film 21 from the pressure-sensitive adhesive sheet 1. About this test piece, the initial haze value (%) was measured based on JIS K7105 using a haze meter (trade name: NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) (N = 5 average value). In addition, one corner of each test piece was stopped with a clip, suspended in a dryer at 150 ° C. and heated for 2 hours, and then the haze value (%) after heating was measured according to JIS K7105 (average value of N = 5) ).

The absolute value of the value obtained by subtracting the initial haze value from the haze value after heating was defined as a Δhaze value, and evaluation was performed according to the following criteria. In addition, if (DELTA) haze value is 0.15% or less, the precipitation amount of the oligomer from the polyester film used as a 1st base film is sufficiently small, and the influence on a subsequent process can be reduced.
○ (Good): 0.15% or less × (Bad): 0.15% or more

Example 1
(A) Bisphenol A type epoxy compound (trade name: EPICLON H-360, manufactured by DIC: solid content concentration 40% by mass, mass average molecular weight 25000) 100 parts by mass, (B) polyester compound (trade name: Byron GK680, Toyobo 19.0 parts by mass of toluene solution (solid content concentration 30% by mass) and (C) hexamethoxymethyl melamine (trade name: Cymel 303, solid content concentration 100) 11.4 parts by mass (mass%, manufactured by Nippon Cytec Industries, Ltd.) was mixed. The mixed solution was diluted with a mixed solvent of toluene / methyl ethyl ketone (hereinafter also referred to as “MEK”) = 50 mass% / 50 mass% so that the solid content was 3 mass% and stirred. Thereafter, (D) 2.9 parts by mass of a methanol solution of p-toluenesulfonic acid (solid content concentration 50% by mass) was added to obtain a resin layer forming composition.

  The obtained resin layer forming composition was rolled to roll (Roll to Roll) method to form a biaxially stretched polyethylene terephthalate film (trade name: E5001, manufactured by Toyobo Co., Ltd .: 75 μm thick) as a base film. On one surface, it was uniformly coated by the Meyer bar coating method. Thereafter, the base film on which the resin-forming composition is applied is passed through an oven in which hot air at 150 ° C. blows at a wind speed of 8 m / min in 20 seconds to form a resin layer having a thickness of 150 nm, and then the base material on which the resin layer is formed The film was wound into a roll around an ABS core material to obtain a polyester film in which a resin layer having a width of 1050 mm and a length of 4000 m was formed.

  Next, 100 parts by mass of an addition reaction type silicone resin (trade name: KS-774, manufactured by Shin-Etsu Chemical Co., Ltd.) is mixed with toluene / MEK = 50% by mass / 50% by mass with a solid content of 1.5. It diluted and stirred so that it might become mass%. Thereafter, 1 part by mass of a platinum catalyst (trade name: PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to obtain a release layer forming composition.

  Next, by a roll-to-roll method, the release layer forming composition is uniformly applied to the surface opposite to the resin layer of the base film by the Mayer bar coating method so that the thickness after drying becomes 150 nm. Worked. Thereafter, a release layer is formed so that the substrate film coated with the release layer forming composition is passed through an oven in which hot air at 150 ° C. blows at a wind speed of 8 m / min in 20 seconds to obtain a first release film. It was.

  Next, 100 parts by mass of an acrylic pressure-sensitive adhesive (manufactured by Soken Chemical Co., Ltd., trade name “SK Dyne 2971”, mass average molecular weight: 400,000, solid content: 40%), and tolylene diisocyanate curing agent (trade name “ TD-75 ", solid content: 75%, manufactured by Soken Chemical Co., Ltd.) 0.5 parts by mass, and silane coupling agent (trade name" A-50 ", solid content: 50%, manufactured by Soken Chemical Co., Ltd.) 0.2 Mass parts and 40 parts by mass of ethyl acetate were mixed to prepare an adhesive coating solution.

  Next, the pressure-sensitive adhesive coating solution was applied onto the release film by a roll-to-roll method, and dried by heating at 100 ° C. for 5 minutes to obtain a pressure-sensitive adhesive layer having a thickness of 75 μm. Then, a release sheet (trade name: P50LT-H, manufactured by Lintec Corporation: thickness 50 μm) is bonded onto the adhesive layer and wound around an ABS core material to obtain an adhesive sheet wound in a roll shape. It was. The obtained adhesive sheet was evaluated. The composition of the resin layer forming composition, the weight average molecular weight of the component (A), the glass transition temperature (Tg) of the component (B), and the thickness of the resin layer after drying are shown in Table 1 below, and the initial haze value, Δ The evaluation results of haze value and oligomer sealing properties are shown in Table 2 below.

(Example 2)
(B) Implemented except that the polyester compound was 22.22 parts by mass, (C) hexamethoxymethylmelamine was 20 parts by mass, and (D) the methanol solution of p-toluenesulfonic acid was 3.3 parts by mass. The same operation as in Example 1 was performed to obtain a pressure-sensitive adhesive sheet. The composition of the resin layer forming composition is also shown in Table 1 below, and the evaluation results are also shown in Table 2 below.

(Example 3)
(B) The polyester compound is 44.4 parts by mass, (C) hexamethoxymethylmelamine is 13.3 parts by mass, and (D) the methanol solution of p-toluenesulfonic acid is 3.3 parts by mass. In the same manner as in Example 1, a pressure-sensitive adhesive sheet was obtained. The composition of the resin layer forming composition is also shown in Table 1 below, and the evaluation results are also shown in Table 2 below.

Example 4
(A) bisphenol A type epoxy compound (trade name: EPICLON EXA-123, manufactured by DIC Corporation: solid content concentration 30%, mass average molecular weight 45000) is changed to 100 parts by mass, and (B) polyester compound is 14.3 parts by mass. And (C) hexamethoxymethylmelamine is 8.6 parts by mass, and (D) a methanol solution of p-toluenesulfonic acid (solid content concentration: 50% by mass) is added by 2.1 parts by mass. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the product was obtained. The composition of the resin layer forming composition is also shown in Table 1 below, and the evaluation results are also shown in Table 2 below.

(Example 5)
(B) Except having changed into the toluene solution (solid content concentration 30 mass%) of the polyester compound (Brand name: Byron GK810, Toyobo Co., Ltd. product: number average molecular weight 6000, glass transition temperature 46 degreeC), it is the same as that of Example 1. To obtain a pressure-sensitive adhesive sheet. The composition of the resin layer forming composition is also shown in Table 1 below, and the evaluation results are also shown in Table 2 below.

(Example 6)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the coating amount was changed so that the thickness of the resin layer after drying was 75 nm. The composition of the resin layer forming composition is also shown in Table 1 below, and the evaluation results are also shown in Table 2 below.

(Comparative Example 1)
(B) The component is not blended, (C) Hexamethoxymethylmelamine is 10 parts by mass, and (D) p-toluenesulfonic acid methanol solution is 2.5 parts by mass. To obtain a pressure-sensitive adhesive sheet. The composition of the resin layer forming composition is also shown in Table 1 below, and the evaluation results are also shown in Table 2 below.

(Comparative Example 2)
(B) The polyester compound is 222.2 parts by mass, (C) hexamethoxymethylmelamine is 26.7 parts by mass, and (D) the methanol solution of p-toluenesulfonic acid is 6.7 parts by mass. In the same manner as in Example 1, a pressure-sensitive adhesive sheet was obtained. The composition of the resin layer forming composition is also shown in Table 1 below, and the evaluation results are also shown in Table 2 below.

  As can be seen from Table 2, the pressure-sensitive adhesive sheets according to Examples 1 to 6 all had good oligomer sealing properties. As a result, the resin layer was formed using a resin layer forming composition in which a predetermined amount of the components (A) to (C) was blended, and the Δhaze value was 0.15%. Therefore, it is considered that the oligomer was sufficiently sealed. In Comparative Example 1 and Comparative Example 2, only a pressure-sensitive adhesive sheet having a poor oligomer sealing property was obtained.

1, 2, 3, 4 Adhesive sheet 5 Transparent conductive film 10 First release film 11 Base film (first base film)
DESCRIPTION OF SYMBOLS 12 Resin layer 13 Release layer 14 Adhesive layer 21 2nd release film 22 Base film (2nd base film)
23 functional layer 51 support 52a, 52b hard coat layer 53 transparent conductive layer

Claims (10)

A release having a first base film made of a polyester film, a resin layer provided on one surface of the first base film, and a release layer provided on the other surface of the first base film Mold film,
An adhesive layer provided on the surface of the release layer,
The resin layer comprises (A) 50% by mass to 80% by mass of a bisphenol A type epoxy compound, (B) 5% by mass to 30% by mass of a polyester compound, and (C) 10% by mass to 40% by mass. A pressure-sensitive adhesive sheet obtained by curing a resin composition containing the polyfunctional amino compound.   The pressure-sensitive adhesive layer includes a core material layer, a first pressure-sensitive adhesive layer provided on one surface of the core material layer, and a second pressure-sensitive adhesive layer provided on the other surface of the core material layer. The pressure-sensitive adhesive sheet according to claim 1, comprising:   Furthermore, the adhesive sheet of Claim 1 or Claim 2 provided with the 2nd base film provided on the said adhesive layer.   Furthermore, the adhesive sheet of Claim 3 provided with the functional layer provided on the said 2nd base film.   The pressure-sensitive adhesive sheet according to claim 4, wherein the functional layer is a transparent conductive layer.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the release layer is obtained by curing addition-reactive silicone.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the bisphenol A-type epoxy compound has a mass average molecular weight of 10,000 or more and 50,000 or less.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein a glass transition temperature (Tg) of the polyester compound is 0 ° C or higher and 50 ° C or lower.   The said resin layer heats the coating layer formed by apply | coating the solution of the said resin composition on the said 1st base film, and is any one of Claims 1-8 made into a hardened film. The pressure-sensitive adhesive sheet according to item.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 9, wherein the resin layer has a thickness of 50 nm to 500 nm.

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