JP2018002917A - Optical double-sided adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical double-sided adhesive tape appropriate for simultaneously realizing excellent hand-tearability and high reworkability, while having a polyester base material.SOLUTION: An adhesive tape X has a laminate structure including a base material 10 being a transparent base material, an adhesive layer 11, and an adhesive layer 12. The base material 10 is a polyester base material uniaxially drawn in a base-material width direction, positioned between the adhesive layers 11, 12 and has a thickness of 75 μm or more. The adhesive tape X has an Elmendorf tear strength of 0.5 N or less in the base-material width direction. The adhesive tape X has an Elmendorf tear strength of 1 N or more in a base-material machine direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a double-sided pressure-sensitive adhesive tape having optical transparency for optical use.

  In the technical field of flat panel displays, optical double-sided pressure-sensitive adhesive tapes are used for manufacturing display devices. Specifically, a display device such as a liquid crystal display and an input device such as a touch panel have a laminated structure including various substrates and film bodies, and in order to join between predetermined parts adjacent in the laminated structure, Alternatively, a transparent double-sided pressure-sensitive adhesive tape may be used to fill a gap between adjacent parts. Such optical double-sided pressure-sensitive adhesive tape is described in, for example, Patent Documents 1 to 3 below.

JP 2012-78431 A Japanese Patent Laid-Open No. 2015-200698 Japanese Unexamined Patent Publication No. 2016-26321

  As the base material for the optical double-sided pressure-sensitive adhesive tape described above, a polyester-based base material may be employed because it is excellent in various properties such as heat resistance, transparency, and dimensional stability. For example, a PET film which is a polyester-based substrate for optical applications such as a double-sided adhesive tape for optical use, the raw resin material is extruded into a film by the T-die method in the manufacturing process, and then the flow direction or the machine direction in the film. It is known that a biaxial stretching process including stretching in the (MD) and stretching in the width direction (TD) is often performed.

  Moreover, about the double-sided adhesive tape for optics, from a viewpoint of work efficiency etc., favorable hand cutting property may be calculated | required.

  The present invention has been conceived under the circumstances as described above, and is an optical suitable for realizing both good hand cutting performance and high reworkability while having a polyester base material. It is an object of the present invention to provide a double-sided pressure-sensitive adhesive tape.

  The optical double-sided pressure-sensitive adhesive tape provided by the present invention has a laminated structure including a first pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer, and a transparent substrate between the first and second pressure-sensitive adhesive layers. The transparent substrate is a uniaxially stretched polyester-based substrate in the substrate width direction and has a thickness of 75 μm or more. The polyester base material refers to a base material such as a film or a sheet containing a polyester resin in the largest weight ratio in the constituent material. The base material width direction uniaxially stretched polyester base material refers to a width direction orthogonal to the flow direction or the machine direction (MD) of, for example, a film-like extrudate after the raw material resin material is extruded in the manufacturing process of the polyester base material ( TD) refers to a polyester base material that has undergone uniaxial stretching. The first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer contains, for example, at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a rubber-based pressure-sensitive adhesive. In this optical double-sided pressure-sensitive adhesive tape, the Elmendorf tear strength in the substrate width direction is 0.5 N or less, and the Elmendorf tear strength in the substrate machine direction is 1 N or more. The optical double-sided pressure-sensitive adhesive tape having the above configuration may take a sheet form with a release liner for covering and protecting the adhesive surface of each pressure-sensitive adhesive layer, or the optical double-sided pressure-sensitive adhesive tape and release liner. And may be wound in a roll shape with a release liner so as to be alternately arranged.

  The transparent base material which this double-sided adhesive tape for optics has is a polyester-type base material as mentioned above. Such a configuration is suitable for enjoying various characteristics that are easily manifested in a polyester base material such as heat resistance, transparency, and dimensional stability in the double-sided pressure-sensitive adhesive tape substrate and, in turn, this optical double-sided pressure-sensitive adhesive tape. is there.

  Moreover, the transparent base material which this double-sided adhesive tape for optics has is a width direction uniaxially stretched polyester-type base material 75 micrometers or more in thickness as mentioned above. The tear strength such as Elmendorf tear strength in the double-sided pressure-sensitive adhesive tape is strongly governed by the mechanical properties of the base material. In such a double-sided pressure-sensitive adhesive tape for optical use, the Elmendorf tear strength in the base material width direction is 0. It is suitable for realizing the above configuration in which the Elmendorf tear strength in the substrate machine direction is 5N or less and 1N or more.

  In addition, as described above, this optical double-sided pressure-sensitive adhesive tape has an Elmendorf tear strength in the substrate width direction of 0.5 N or less and an Elmendorf tear strength in the substrate machine direction of 1 N or more. Such a configuration is suitable for realizing good hand-cutting properties in the width direction of the substrate in the present double-sided pressure-sensitive adhesive tape, in which the Elmendorf tear strength is relatively significantly lower than 0.5N. At the same time, the configuration that the Elmendorf tear strength is 1N or more in the substrate machine direction, which is twice or more the substrate width direction, increases the directivity of the optical double-sided pressure-sensitive adhesive tape with respect to tearing in the substrate width direction. It is suitable for. Therefore, when the optical double-sided pressure-sensitive adhesive tape is in a state of being bonded to the adherend, the configuration is such that the adhesive tape is removed from the adherend by applying a peeling force to the substrate machine direction of the adhesive tape. Suitable for proper peeling without tearing. Specifically, after the optical double-sided pressure-sensitive adhesive tape is bonded to the adherend, once peeled and bonded again (rework work), a peeling force is applied to the substrate machine direction of the pressure-sensitive adhesive tape. Thus, the adhesive tape is suitably peeled off from the adherend without tearing. Optical double-sided pressure-sensitive adhesive tapes that are easily torn in the substrate machine direction in addition to the substrate width direction tend to tear at the time of peeling in the rework operation, and tend to be difficult to peel off appropriately from the adherend. The optical double-sided pressure-sensitive adhesive tape in which tearing has occurred cannot be used for re-bonding. On the other hand, this optical double-sided pressure-sensitive adhesive tape has a machine direction Elmendorf tear strength that is sufficiently larger than the base material width direction Elmendorf tear strength, which is suitable for realizing good hand tearability in the base material width direction. Therefore, in the rework work, it is suitable for appropriately peeling from the adherend without tearing.

  As described above, the present optical double-sided pressure-sensitive adhesive tape is suitable for realizing both good hand cutting and high reworkability while having a polyester base material.

  Preferably, the thickness of the first pressure-sensitive adhesive layer is 5 μm or more, and the thickness of the second pressure-sensitive adhesive layer is 5 μm or more. Such a configuration is suitable for realizing a sufficient adhesive force to an adherend in an optical double-sided pressure-sensitive adhesive tape.

  Preferably, the optical double-sided pressure-sensitive adhesive tape has a haze in the thickness direction of 3% or less. Such a configuration is suitable for an optical pressure-sensitive adhesive tape that requires transparency.

It is a fragmentary sectional view of the double-sided adhesive tape for optics concerning one embodiment of the present invention.

  FIG. 1 is a partial cross-sectional view of an adhesive tape X that is an optical double-sided adhesive tape according to an embodiment of the present invention. The pressure-sensitive adhesive tape X has a laminated structure including a base material 10 as a transparent base material, a pressure-sensitive adhesive layer 11 as a first pressure-sensitive adhesive layer, and a pressure-sensitive adhesive layer 12 as a second pressure-sensitive adhesive layer. The adhesive tape X can be used in the manufacture of a display device such as a flat panel display. A display device such as a liquid crystal display or an input device such as a touch panel has a laminated structure portion including various substrates and film bodies, and is used for joining adjacent predetermined parts in the laminated structure or adjacent parts. An adhesive tape X can be used to fill the gaps between them.

  The base material 10 which the adhesive tape X has is a part which functions as a support body between the adhesive layers 11 and 12 in the adhesive tape X, and is a base material width direction uniaxially stretched polyester base material having light transmittance. is there.

  The polyester base material refers to a base material such as a film or a sheet containing a polyester resin in the largest weight ratio in the constituent material. Examples of the constituent material of the substrate 10 include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and poly-1,4-cyclohexanedimethylene terephthalate.

  The base material width direction uniaxially stretched polyester base material refers to a width direction orthogonal to the flow direction or the machine direction (MD) of, for example, a film-like extrudate after the raw material resin material is extruded in the manufacturing process of the polyester base material ( TD) refers to a polyester base material that has undergone uniaxial stretching. About the draw ratio of the width direction of the base material 10 which is such a width direction uniaxially stretched polyester base material, it is 2.5 times or more, for example, Preferably it is 3 times or more. Moreover, about the said draw ratio, it is 6 times or less, for example, Preferably it is 5.5 times or less.

  The thickness of the base material 10 is 75 μm or more, preferably 80 μm or more. Moreover, the thickness of the base material 10 is 150 micrometers or less, for example, Preferably it is 125 micrometers or less.

  The in-plane retardation of the substrate 10 is preferably 1500 nm or more, more preferably 3000 nm or more, and more preferably 6000 nm or more. In the present embodiment, the in-plane retardation of the substrate 10 is in a plane parallel to the main surface of the substrate 10 according to birefringence when light having a wavelength of 590 nm is transmitted through the substrate 10 at 23 ° C. Between two orthogonal optical principal axes (slow axis and fast axis) between the polarization component (abnormal ray) oscillating in the direction of the slow axis and the polarization component (ordinary ray) oscillating in the direction of the fast axis This refers to the phase difference that occurs. In the in-plane retardation, the refractive index (relatively large) of extraordinary rays is nx, the refractive index (relatively small) of ordinary rays is ny, and the thickness of the substrate 10 is d (nm). In this case, the value is represented by (nx−ny) × d.

  The surface on the pressure-sensitive adhesive layer 11 side and the surface on the pressure-sensitive adhesive layer 12 side of the substrate 10 may each be subjected to a surface treatment for improving adhesion with the pressure-sensitive adhesive layer. Examples of such surface treatment include physical treatment such as corona treatment and plasma treatment, and chemical treatment such as undercoating treatment.

  The pressure-sensitive adhesive layers 11 and 12 of the pressure-sensitive adhesive tape X each contain a pressure-sensitive adhesive as a main agent and have light transmittance. The main agent is a component that occupies the largest weight ratio among the contained components. The pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 is, for example, at least one selected from the group consisting of an acrylic polymer as an acrylic pressure-sensitive adhesive, a polyurethane as a urethane pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, and a rubber-based pressure-sensitive adhesive. including. From the viewpoint of realizing both the adhesive strength required for the pressure-sensitive adhesive layer of the optical double-sided pressure-sensitive adhesive tape and high transparency, an acrylic polymer is used as the pressure-sensitive adhesive in the pressure-sensitive adhesive layers 11 and 12. Is preferred. Moreover, the adhesive layer 11 has the adhesive surface 11a which can be stuck to a to-be-adhered body, and the adhesive layer 12 has the adhesive surface 12a which can be stuck to an to-be-adhered body.

  When the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 contains an acrylic polymer that is an acrylic pressure-sensitive adhesive, the acrylic polymer is preferably an acrylic acid alkyl ester having a linear or branched alkyl group. And / or a monomer unit derived from a methacrylic acid alkyl ester having a linear or branched alkyl group as a main monomer unit having the largest weight ratio. Hereinafter, “(meth) acryl” means “acryl” and / or “methacryl”.

  (Meth) acrylic acid alkyl ester having a linear or branched alkyl group for forming a monomer unit of the acrylic polymer, that is, a linear chain contained in the monomer component for forming the acrylic polymer. Examples of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, N-butyl (meth) acrylate, s-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meta ) Hexyl acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylic Isooctyl acid, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, (meth) acrylic acid Tridecyl, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isostearyl (meth) acrylate, (meth) acrylic acid Examples thereof include (meth) acrylic acid alkyl esters having a linear or branched alkyl group having 1 to 20 carbon atoms, such as nonadecyl and eicosyl (meth) acrylate. As the (meth) acrylic acid alkyl ester for the acrylic polymer, one kind of (meth) acrylic acid alkyl ester may be used, or two or more kinds of (meth) acrylic acid alkyl esters may be used. . In this embodiment, the (meth) acrylic acid alkyl ester for the acrylic polymer is preferably at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, and isostearyl acrylate. Is used.

  The proportion of the monomer unit derived from the (meth) acrylic acid alkyl ester having a linear or branched alkyl group in the acrylic polymer is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably Is 70% by weight or more, more preferably 80% by weight or more, more preferably 90% by weight or more. That is, the proportion of the (meth) acrylic acid alkyl ester in the monomer component composition of the raw material for forming the acrylic polymer is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more. More preferably, it is 80 weight% or more, More preferably, it is 90 weight% or more. The acrylic polymer has a monomer unit structure derived from the monomer component composition with such a (meth) acrylic acid alkyl ester ratio. The configuration relating to the proportion of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group includes basic properties such as the tackiness of an acrylic polymer as an acrylic adhesive, and includes the acrylic polymer. This is suitable for properly expressing the formed pressure-sensitive adhesive layer.

  The acrylic polymer contained in the pressure-sensitive adhesive layer 11 and the pressure-sensitive adhesive layer 12 may include a monomer unit derived from an alicyclic monomer. Examples of the alicyclic monomer for forming the monomer unit of the acrylic polymer, i.e., the alicyclic monomer contained in the monomer component for forming the acrylic polymer, include (meth) acrylic acid cycloalkyl ester, (Meth) acrylic acid ester having a cyclic hydrocarbon ring, and (meth) acrylic acid ester having three or more hydrocarbon rings. Examples of the (meth) acrylic acid cycloalkyl ester include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate. Examples of the (meth) acrylic acid ester having a bicyclic hydrocarbon ring include bornyl (meth) acrylate and isobornyl (meth) acrylate. Examples of (meth) acrylic acid esters having three or more hydrocarbon rings include, for example, (meth) acrylic acid dicyclopentanyl, (meth) acrylic acid dicyclopentanyloxyethyl, (meth) acrylic acid tricyclopenta Nyl, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, and 2-ethyl-2-adamantyl (meth) acrylate. As an alicyclic monomer for an acrylic polymer, one type of alicyclic monomer may be used, or two or more types of alicyclic monomers may be used. In the present embodiment, at least one selected from the group consisting of cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, and isobornyl methacrylate is preferably used as the alicyclic monomer for the acrylic polymer.

  The proportion of the monomer unit derived from the alicyclic monomer in the acrylic polymer is preferably 5 to 60% by weight from the viewpoint of realizing appropriate flexibility in the pressure-sensitive adhesive layer formed by including the acrylic polymer. More preferably, it is 10 to 50% by weight.

  The acrylic polymer contained in the pressure-sensitive adhesive layer 11 and the pressure-sensitive adhesive layer 12 may include a monomer unit derived from a hydroxyl group-containing monomer. A hydroxyl group-containing monomer is a monomer that will have at least one hydroxyl group in the monomer unit. In the case where the acrylic polymer in the pressure-sensitive adhesive layers 11 and 12 includes a hydroxyl group-containing monomer unit, it is easy to obtain adhesiveness and appropriate cohesive force in the pressure-sensitive adhesive layers 11 and 12.

  Examples of the hydroxyl group-containing monomer for forming a monomer unit of the acrylic polymer, that is, the hydroxyl group-containing monomer contained in the monomer component for forming the acrylic polymer include, for example, a hydroxyl group-containing (meth) acrylic acid ester, vinyl alcohol , And allyl alcohol. Examples of the hydroxyl group-containing (meth) acrylic acid ester include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic acid 4- Hydroxybutyl, 6-hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxydecyl (meth) acrylate, hydroxylauryl (meth) acrylate, and (meth) acrylic acid (4-hydroxymethylcyclohexyl) And methyl. As the hydroxyl group-containing monomer for the acrylic polymer, one kind of hydroxyl group-containing monomer may be used, or two or more kinds of hydroxyl group-containing monomers may be used. In this embodiment, the hydroxyl group-containing monomer for the acrylic polymer is preferably 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylic acid 4 At least one selected from the group consisting of -hydroxybutyl and 4-hydroxybutyl methacrylate is used.

  The proportion of the monomer unit derived from the hydroxyl group-containing monomer in the acrylic polymer is preferably 1% by weight or more, more preferably 2% by weight or more, more preferably 3% by weight or more, more preferably 5% by weight or more, and more preferably. Is 7% by weight or more, more preferably 10% by weight or more. The ratio of the monomer unit derived from the hydroxyl group-containing monomer in the acrylic polymer is preferably 20% by weight or less, more preferably 18% by weight or less. These configurations relating to the proportion of the hydroxyl group-containing monomer are suitable for realizing adhesiveness and appropriate cohesive force in the pressure-sensitive adhesive layer formed by including the acrylic polymer.

  The acrylic polymer contained in the pressure-sensitive adhesive layer 11 and the pressure-sensitive adhesive layer 12 may include a monomer unit derived from a nitrogen atom-containing monomer. A nitrogen atom-containing monomer is a monomer that will have at least one nitrogen atom in the monomer unit. When the acrylic polymer in the pressure-sensitive adhesive layers 11 and 12 contains a nitrogen atom-containing monomer unit, the pressure-sensitive adhesive layers 11 and 12 can easily obtain hardness and good adhesion reliability.

  Examples of the nitrogen atom-containing monomer for forming the monomer unit of the acrylic polymer, that is, the nitrogen atom-containing monomer contained in the monomer component for forming the acrylic polymer include N-vinyl cyclic amide and (meth) Examples include acrylamides. Examples of N-vinyl cyclic amides that are nitrogen atom-containing monomers include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, and N-vinyl. -1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione. Examples of (meth) acrylamides that are nitrogen atom-containing monomers include (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nn-butyl (meth) acrylamide, N-octyl ( Mention may be made of (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide and N, N-diisopropyl (meth) acrylamide. As the nitrogen atom-containing monomer for the acrylic polymer, one kind of nitrogen atom-containing monomer may be used, or two or more kinds of nitrogen atom-containing monomers may be used. In this embodiment, N-vinyl-2-pyrrolidone is preferably used as the nitrogen atom-containing monomer for the acrylic polymer.

  In the acrylic polymer, the ratio of the monomer unit derived from the nitrogen atom-containing monomer is a pressure-sensitive adhesive layer formed by including the acrylic polymer, from the viewpoint of realizing appropriate hardness, adhesiveness, and transparency, Preferably it is 1 weight% or more, More preferably, it is 3 weight% or more, More preferably, it is 5 weight% or more. In the acrylic polymer, the proportion of the monomer unit derived from the nitrogen atom-containing monomer is too hard to achieve sufficient transparency in the pressure-sensitive adhesive layer formed by including the acrylic polymer. From the viewpoint of realizing good adhesion reliability by suppressing the above, it is preferably 30% by weight or less, more preferably 25% by weight or less.

  The acrylic polymer contained in the pressure-sensitive adhesive layer 11 and the pressure-sensitive adhesive layer 12 may include a monomer unit derived from a carboxy group-containing monomer. The carboxy group-containing monomer is a monomer that has at least one carboxy group in the monomer unit. When the acrylic polymer in the pressure-sensitive adhesive layers 11 and 12 includes a carboxy group-containing monomer unit, good adhesive reliability may be easily obtained in the pressure-sensitive adhesive layers 11 and 12.

  Examples of the carboxy group-containing monomer for forming the monomer unit of the acrylic polymer, that is, the carboxy group-containing monomer contained in the monomer component for forming the acrylic polymer include, for example, (meth) acrylic acid, itaconic acid, Mention may be made of maleic acid, fumaric acid, crotonic acid and isocrotonic acid. As the carboxy group-containing monomer for the acrylic polymer, one kind of carboxy group-containing monomer may be used, or two or more kinds of carboxy group-containing monomers may be used. In this embodiment, acrylic acid is preferably used as the carboxy group-containing monomer for the acrylic polymer.

  The ratio of the monomer unit derived from the carboxy group-containing monomer in the acrylic polymer is the same as that of the polar group when the polar group is present on the adherend surface in the pressure-sensitive adhesive layer formed by including the acrylic polymer. From the viewpoint of obtaining a contribution of interaction and ensuring good adhesion reliability, the content is preferably 0.1% by weight or more, more preferably 0.5% by weight or more. Moreover, the ratio of the monomer unit derived from the carboxy group-containing monomer in the acrylic polymer suppresses becoming too hard in the pressure-sensitive adhesive layer formed by including the acrylic polymer, thereby realizing good adhesion reliability. From this viewpoint, it is preferably 20% by weight or less, more preferably 15% by weight or less.

  The acrylic polymer contained in the pressure-sensitive adhesive layer 11 or the pressure-sensitive adhesive layer 12 may have a crosslinked structure derived from a polyfunctional (meth) acrylate that is a copolymerizable crosslinking agent. Examples of polyfunctional (meth) acrylates include 1,6-hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, and (poly) propylene glycol di (meta). ) Acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methanetri (Meth) acrylate, allyl (meth) acrylate, and vinyl (meth) acrylate. As the polyfunctional (meth) acrylate for the acrylic polymer, one kind of polyfunctional (meth) acrylate may be used, or two or more kinds of polyfunctional (meth) acrylates may be used. In this embodiment, the polyfunctional (meth) acrylate for the acrylic polymer is preferably selected from the group consisting of 1,6-hexanediol diacrylate, dipentaerythritol hexaacrylate, and trimethylolpropane triacrylate. At least one kind is used.

  The proportion of the monomer unit derived from polyfunctional (meth) acrylate in the acrylic polymer is preferably 0.01% by weight or more, more preferably 0.03% by weight or more, more preferably 0.05% by weight or more. . The ratio of the monomer unit derived from polyfunctional (meth) acrylate in the acrylic polymer is preferably 1% by weight or less, more preferably 0.5% by weight or less. These configurations relating to the ratio of the polyfunctional (meth) acrylate are suitable for realizing appropriate hardness and adhesiveness in the pressure-sensitive adhesive layer formed by including the acrylic polymer.

  When the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 contains the above acrylic polymer as a pressure-sensitive adhesive, the content of the acrylic polymer in the pressure-sensitive adhesive layer is, for example, 85 to 100% by weight.

  The pressure-sensitive adhesive layers 11 and 12 may each contain, for example, an acrylic oligomer having a raw material monomer composition different from that of the above-mentioned acrylic polymer from the viewpoint of realizing high adhesiveness at room temperature. When the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 contains such an acrylic oligomer, the content of the acrylic oligomer in the pressure-sensitive adhesive layer is 100 parts by weight of the pressure-sensitive adhesive or acrylic polymer in the pressure-sensitive adhesive layer. For example, it is 0.1 to 20 parts by weight.

  The oligomer is preferably a (meth) acrylic monomer unit derived from a (meth) acrylic acid ester having a cyclic structure (ring-containing (meth) acrylic acid ester) and a linear or branched alkyl group. And a monomer unit derived from an acid alkyl ester.

  The ring-containing (meth) acrylic acid ester for forming the monomer unit of the oligomer, that is, the ring-containing (meth) acrylic acid ester contained in the monomer component for forming the oligomer includes, for example, (meth) acrylic acid Examples include cycloalkyl esters, (meth) acrylic acid esters having a bicyclic hydrocarbon ring, (meth) acrylic acid esters having three or more hydrocarbon rings, and (meth) acrylic acid esters having an aromatic ring. It is done. Examples of the (meth) acrylic acid cycloalkyl ester include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate. Examples of the (meth) acrylic acid ester having a bicyclic hydrocarbon ring include bornyl (meth) acrylate and isobornyl (meth) acrylate. Examples of (meth) acrylic acid esters having three or more hydrocarbon rings include, for example, (meth) acrylic acid dicyclopentanyl, (meth) acrylic acid dicyclopentanyloxyethyl, (meth) acrylic acid tricyclopenta Nyl, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, and 2-ethyl-2-adamantyl (meth) acrylate. Examples of the (meth) acrylic acid ester having an aromatic ring include phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate. As the ring-containing (meth) acrylic acid ester for the oligomer, one kind of ring-containing (meth) acrylic acid ester may be used, or two or more kinds of ring-containing (meth) acrylic acid esters may be used. . In the present embodiment, at least one selected from the group consisting of dicyclopentanyl acrylate and dicyclopentanyl methacrylate is preferably used as the ring-containing (meth) acrylic acid ester for the oligomer.

  The proportion of the monomer unit derived from the ring-containing (meth) acrylic acid ester in the oligomer is preferably 10 to 90% by weight from the viewpoint of realizing appropriate flexibility in the pressure-sensitive adhesive layer formed including the oligomer. More preferably, it is 20-80 weight%, More preferably, it is 35-80 weight%.

  (Meth) acrylic acid alkyl ester having a linear or branched alkyl group for forming a monomer unit of the oligomer, that is, linear or branched, contained in the monomer component for forming the oligomer Examples of (meth) acrylic acid alkyl esters having a chain alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, (meth) N-butyl acrylate, s-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) acrylic acid Hexyl, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate Nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, Tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, And (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms, such as eicosyl (meth) acrylate. As the (meth) acrylic acid alkyl ester for the oligomer, one type of (meth) acrylic acid alkyl ester may be used, or two or more types of (meth) acrylic acid alkyl ester may be used. In this embodiment, methyl methacrylate is preferably used as the (meth) acrylic acid alkyl ester for the oligomer.

  The proportion of monomer units derived from (meth) acrylic acid alkyl ester having a linear or branched alkyl group in the oligomer realizes an appropriate elastic modulus in the pressure-sensitive adhesive layer formed by including the oligomer. From this viewpoint, it is preferably 10 to 90% by weight, more preferably 15 to 80% by weight, and more preferably 20 to 60% by weight.

  The oligomer is derived from a carboxy group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, a cyano group-containing monomer, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, an isocyanate group-containing monomer, or an imide group-containing monomer. It may contain a monomer unit.

  The weight average molecular weight (Mw) of the oligomer is, for example, 1000 to 30000, preferably 1000 to 20000, and more preferably 1500 to 10,000. From the viewpoint of ensuring good adhesive strength in the pressure-sensitive adhesive layer formed by including the oligomer, the weight average molecular weight of the oligomer is preferably 1000 or more. On the other hand, it is preferable that the weight average molecular weight of the oligomer is 30000 or less from the viewpoint of ensuring the adhesive strength at room temperature in the pressure-sensitive adhesive layer formed by including the oligomer.

The weight average molecular weight of the oligomer can be measured by a gel permeation chromatograph (GPC) method. For example, a weight average molecular weight (Mw) can be obtained as a standard polystyrene conversion value under the following measurement conditions using a GPC measuring device (trade name “HLC-8120GPC”, manufactured by Tosoh Corporation).
Column: TSKgel SuperAWM-H (upstream, manufactured by Tosoh Corporation), TSKgel SuperAW4000 (manufactured by Tosoh Corporation) and TSKgel SuperAW2500 (downstream, manufactured by Tosoh Corporation) are connected in series. Column size: 6 for each column 0.0mmφ × 150mm
Column temperature (measurement temperature): 40 ° C
・ Eluent: Tetrahydrofuran (THF)
・ Flow rate: 0.4 mL / min ・ Sample injection volume: 20 μL
Sample concentration: about 2.0 g / L (tetrahydrofuran solution)
Standard sample: Polystyrene Detector: Differential refractometer (RI)

  Each of the pressure-sensitive adhesive layers 11 and 12 may contain a silane coupling agent. Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-aminopropyltrimethoxysilane. . Examples of the silane coupling agent include commercially available products such as “KBM-403” (manufactured by Shin-Etsu Chemical Co., Ltd.). As the silane coupling agent, γ-glycidoxypropyltrimethoxysilane is preferable.

  When the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 contains a silane coupling agent, the content of the silane coupling agent in the pressure-sensitive adhesive layer is 100 parts by weight of the pressure-sensitive adhesive or acrylic polymer in the pressure-sensitive adhesive layer. On the other hand, it is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more. The content of the silane coupling agent in the pressure-sensitive adhesive layer is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, with respect to 100 parts by weight of the acrylic polymer. The composition relating to the content of the silane coupling agent is suitable for realizing high adhesion under humidified conditions, particularly high adhesion to glass, in the pressure-sensitive adhesive layer formed by including the silane coupling agent. It is.

  Each of the pressure-sensitive adhesive layers 11 and 12 may contain an ultraviolet absorber. The ultraviolet absorber is a chemical species that can efficiently absorb ultraviolet rays and can convert the absorbed energy into heat, infrared rays, or the like and release it. Examples of such UV absorbers include benzotriazole UV absorbers, hydroxyphenyl triazine UV absorbers, salicylic acid ester UV absorbers, benzophenone UV absorbers, oxybenzophenone UV absorbers, and cyanoacrylates. An ultraviolet absorber is mentioned. The pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 may contain one type of ultraviolet absorber, or may contain two or more types of ultraviolet absorbers.

  Examples of the benzotriazole ultraviolet absorber include 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole (trade name “TINUVIN PS”, manufactured by BASF), benzenepropanoic acid 3- (2H -Benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy alkyl ester having 7 to 9 carbon atoms (trade name “TINUVIN 384-2”, manufactured by BASF), octyl 3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- Mixture of (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate (trade name “TINUVIN 109”, manufactured by BASF), 2- (2H-benzotriazol-2-yl) -4,6-bis ( 1-Methyl-1-phenylethyl) phenol (trade name “TI NUVIN 900 ", manufactured by BASF), 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) Reaction of phenol (trade name “TINUVIN 928”, manufactured by BASF), methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate and polyethylene glycol 300 Product (trade name “TINUVIN 1130”, manufactured by BASF), 2- (2H-benzotriazol-2-yl) -p-cresol (trade name “TINUVIN P”, manufactured by BASF), 2 (2H-benzotriazole- 2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (trade name “TINUVIN 234”, manufactured by BASF), 2- [5-chloro-2H-benzotriazol-2-yl] -4-Methyl-6- (tert-butyl) phenol (trade name "TINUVIN 326", manufactured by BASF), 2- (2H- Benzotriazol-2-yl) -4,6-di-tert-pentylphenol (trade name “TINUVIN 328”, manufactured by BASF), 2- (2H-benzotriazol-2-yl) -4- (1,1 , 3,3-tetramethylbutyl) phenol (trade name “TINUVIN 329”, manufactured by BASF), 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1, 3,3-tetramethylbutyl) phenol] (trade name “TINUVIN 360”, manufactured by BASF), 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol (trade name “TINUVIN 571 ", Manufactured by BASF) 2- [2-hydroxy-3- (3,4,5,6-tetrahydrophthalimido-methyl) -5-methylphenyl] benzotriazole (trade name" Sumisorb 250 ", Sumitomo Chemical Co., Ltd.) And 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4-tert-octylpheno Le] (trade name "ADK STAB LA-31", Ltd. ADEKA), and the like.

  Examples of the hydroxyphenyl triazine-based ultraviolet absorber include 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl and [(carbon Reaction product with several 10 to 16 alkyloxy) methyl] oxirane (trade name “TINUVIN 400”, manufactured by BASF), 2- [4,6-bis (2,4-dimethylphenyl) -1,3, 5-Triazin-2-yl] -5- [3- (dodecyloxy) -2-hydroxypropoxy] phenol), 2- (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethyl) Reaction product of (phenyl) -1,3,5-triazine and (2-ethylhexyl) -glycidic acid ester (trade name “TINUVIN 405”, manufactured by BASF), 2,4-bis (2-hydroxy-4- Butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3,5-triazine (trade name “TINUVIN 460”, manufactured by BASF) -(4,6-Diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol (trade name “TINUVIN 1577”, manufactured by BASF), 2- (4,6 -Diphenyl-1,3,5-triazin-2-yl) -5- [2- (2-ethylhexanoyloxy) ethoxy] -phenol (trade name “ADK STAB LA-46”, manufactured by ADEKA Corporation), and 2- (2-Hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine (trade name “TINUVIN 479”, manufactured by BASF ).

  Examples of salicylic acid ester UV absorbers include phenyl 2-acryloyloxybenzoate, phenyl 2-acryloyloxy-3-methylbenzoate, phenyl 2-acryloyloxy-4-methylbenzoate, phenyl 2-acryloyloxy-5-methylbenzoate. , Phenyl 2-acryloyloxy-3-methoxybenzoate, phenyl 2-hydroxybenzoate, phenyl 2-hydroxy-3-methylbenzoate, phenyl 2-hydroxy-4-methylbenzoate, phenyl 2-hydroxy-5-methylbenzoate, phenyl 2 -Hydroxy-3-methoxybenzoate and 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate (trade name “TINUVIN 120”, manufactured by BASF).

  Examples of the benzophenone ultraviolet absorber and oxybenzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and 2-hydroxy. -4-Octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone (trade name “KEMISORB 111”, Chemipro Kasei Co., Ltd. 2,2 ′, 4,4′-tetrahydroxybenzophenone (trade name “SEESORB 106”, manufactured by Cypro Kasei Co., Ltd.), and 2,2′-dihydroxy-4,4′-dimethoxybenzophenone.

  Examples of the cyanoacrylate ultraviolet absorber include alkyl 2-cyanoacrylate, cycloalkyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate, and alkynyl 2-cyanoacrylate.

  From the viewpoint that the ultraviolet absorber contained in the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 has high ultraviolet light absorption and high light stability, and from the viewpoint of easily obtaining a highly transparent pressure-sensitive adhesive layer. Preferably, it is at least one selected from the group consisting of benzotriazole-based UV absorbers, hydroxyphenyltriazine-based UV absorbers, and benzophenone-based UV absorbers. The ultraviolet absorber contained in the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 is more preferably a nitrogen atom in which a phenyl group having a hydrocarbon group having 6 or more carbon atoms and a hydroxyl group as a substituent constitutes a benzotriazole ring Is a benzotriazole-based ultraviolet absorber bonded to

  When the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 contains an ultraviolet absorber, the content of the ultraviolet absorber in the pressure-sensitive adhesive layer is high by controlling the transmittance of light having a wavelength of 350 nm in the pressure-sensitive adhesive layer. From the viewpoint of realizing absorbency, it is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, more preferably 0.0 parts by weight or more with respect to 100 parts by weight of the pressure-sensitive adhesive or acrylic polymer in the pressure-sensitive adhesive layer. 1 part by weight or more. In addition, the content of the UV absorber in the pressure-sensitive adhesive layer suppresses the occurrence of yellowing phenomenon of the pressure-sensitive adhesive accompanying the addition of the UV absorber in the pressure-sensitive adhesive layer, thereby realizing excellent optical properties and high transparency. From the viewpoint, the amount is preferably 10 parts by weight or less, more preferably 9 parts by weight or less, more preferably 8 parts by weight or less with respect to 100 parts by weight of the pressure-sensitive adhesive or acrylic polymer in the pressure-sensitive adhesive layer.

  Each of the pressure-sensitive adhesive layers 11 and 12 may contain a light stabilizer. When each of the pressure-sensitive adhesive layers 11 and 12 contains a light stabilizer, it preferably contains both an ultraviolet absorber. A light stabilizer is a chemical species that can trap radicals that can be generated by irradiation with light such as ultraviolet rays. Examples of the light stabilizer include amine light stabilizers such as phenol light stabilizers, phosphorus light stabilizers, thioether light stabilizers, and hindered amine stabilizers. The pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 may contain one type of light stabilizer, or may contain two or more types of light stabilizer.

  Examples of phenolic light stabilizers include 2,6-di-tert-butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-tert-butylphenol, and 2,6-di-tert-butyl- 4-ethylphenol, butylated hydroxyanisole, n-octadecyl 3- (4-hydroxy-3,5-di-tert-butylphenyl) propionate, distearyl (4-hydroxy-3-methyl-5-tert-butyl) Benzyl malonate, tocopherol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-methylenebis (2 , 6-di-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-m-cresol), 4,4′-thiobis (6-tert-butyl-m-cresol), styrenated phenol, N, N'-hexamethylenebis (3,5-di-tert-butyl-4- Roxyhydrocinnamide, bis (3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid ethyl ester) calcium, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) ) Butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [3- (3,5-di-tert-butyl) -4-hydroxyphenyl) propionyloxymethyl] methane, 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2′-methylenebis (4 -Methyl-6-cyclohexylphenol), 2,2'-methylenebis [6- (1-methylcyclohexyl) -p-cresol], 1,3,5-tris (4-tert-butyl-3-hydroxy-2, 6-dimethylbenzyl) isocyanuric acid, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxy) Cybenzyl) isocyanuric acid, triethylene glycol-bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], 2,2′-oxamidobis [ethyl 3- (3,5-di-tert -Butyl-4-hydroxyphenyl) propionate], 6- (4-hydroxy-3,5-di-tert-butylanilino) -2,4-dioctylthio-1,3,5-triazine, bis [2-tert- Butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl] terephthalate, 3,9-bis {2- [3- (3-tert-butyl-4-hydroxy- 5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] undecane, and 3,9-bis {2- [3- (3, 5-Di-tert-butyl-4-hydroxyphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxa Pirro [5.5], and undecane.

  Examples of phosphorous light stabilizers include trisnonylphenyl phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tris [2-tert-butyl-4- (3-tert-butyl-4). -Hydroxy-5-methylphenylthio) -5-methylphenyl] phosphite, tridecyl phosphite, octyl diphenyl phosphite, di (decyl) monophenyl phosphite, di (tridecyl) pentaerythritol diphosphite, distearyl penta Erythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methyl) Phenyl) pentaerythritol diphosphite, bis (2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite Tetra (tridecyl) isopropylidenediphenol diphosphite, tetra (tridecyl) -4,4'-n-butylidenebis (2-tert-butyl-5-methylphenol) diphosphite, hexa (tridecyl) -1,1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butanetriphosphite, tetrakis (2,4-di-tert-butylphenyl) biphenylene diphosphonite, 9,10-dihydro-9-oxa -10-phosphaphenanthrene-10-oxide and tris (2-[(2,4,8,10-tetrakis-tert-butyldibenzo [d, f] [1,3,2] dioxaphosphine Pin-6-yl) oxy] ethyl) amine.

  Examples of the thioether-based light stabilizer include dialkylthiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate, and tetrakis [methylene (3-dodecylthio) propionate]. Examples thereof include β-alkyl mercaptopropionic acid ester compounds of polyols such as methane.

  Examples of the amine light stabilizer include a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (trade name “TINUVIN 622”, manufactured by BASF), The polymer and N, N ′, N ″, N ′ ″-tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) ) Amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine reaction product (trade name “TINUVIN 119”, manufactured by BASF), poly [{6- (1 , 1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2--4-diyl} {2,2,6,6-tetramethyl-4-piperidyl} imino] hexamethylene {(2 , 2,6,6-tetramethyl-4-piperidyl) imino}) (trade name “TINUVIN 944”, manufactured by BASF), bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (product) Name TINUVIN 770 , Manufactured by BASF), reaction product of bis (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide and octane (Trade name “TINUVIN 123”, manufactured by BASF), bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxy Phenyl] methyl] butyl malonate (trade name “TINUVIN 144”, manufactured by BASF), cyclohexane and N-butyl peroxide 2,2,6,6-tetramethyl-4-piperidineamine-2,4,6-trichloro -1,3,5-triazine reaction product and 2-aminoethanol reaction product (trade name “TINUVIN 152”, manufactured by BASF), bis (1,2,2,6,6-pentamethyl-4) -Piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidylsebake (Trade name “TINUVIN 292”, manufactured by BASF), and 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and 3.9 -Bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane mixed ester (trade name “ADK STAB LA-63P”, ADEKA Corporation Manufactured). As the amine stabilizer, a hindered amine stabilizer is particularly preferable.

  When the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 contains a light stabilizer, the content of the light stabilizer in the pressure-sensitive adhesive layer is from the viewpoint of realizing sufficient light resistance in the pressure-sensitive adhesive layer. The amount is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more with respect to 100 parts by weight of the pressure-sensitive adhesive or acrylic polymer in the layer. In addition, the content of the light stabilizer in the pressure-sensitive adhesive layer is such that the pressure-sensitive adhesive in the pressure-sensitive adhesive layer or the acrylic type is used from the viewpoint of realizing high transparency by suppressing coloring due to the light stabilizer in the pressure-sensitive adhesive layer. The amount is preferably 5 parts by weight or less, more preferably 3 parts by weight or less with respect to 100 parts by weight of the polymer.

  The pressure-sensitive adhesive or acrylic polymer contained in the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 may be crosslinked with a crosslinking agent that is not the above-mentioned copolymerizable crosslinking agent. It is possible to adjust the gel fraction of the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 by utilizing the crosslinking of the pressure-sensitive adhesive or acrylic polymer by the crosslinking agent. Examples of such crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metals Examples include salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. The pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 may contain one type of the crosslinking agent, or may contain two or more types of the crosslinking agent. In the present embodiment, an isocyanate crosslinking agent and / or an epoxy crosslinking agent is preferably used.

  Examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. Examples of lower aliphatic polyisocyanates include 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate. Examples of the alicyclic polyisocyanates include cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate. Aromatic polyisocyanates include, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate. Examples of the isocyanate-based crosslinking agent include trimethylolpropane / tolylene diisocyanate adduct (trade name “Coronate L”, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate adduct (trade name “Coronate HL”). And commercial products such as trimethylolpropane / xylylene diisocyanate adduct (trade name “Takenate D-110N”, manufactured by Mitsui Chemicals, Inc.).

  Examples of the epoxy crosslinking agent (polyfunctional epoxy compound) include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, and 1,3-bis (N, N-diglycidylamino). Methyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, Glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycid Examples include dil ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, and bisphenol-S-diglycidyl ether. Moreover, as an epoxy-type crosslinking agent, the epoxy-type resin which has two or more epoxy groups is also mentioned. In addition, examples of the epoxy-based crosslinking agent include commercial products such as a trade name “Tetrad C” (manufactured by Mitsubishi Gas Chemical Company, Inc.).

  When the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 contain the above-described crosslinking agent for crosslinking between acrylic polymers, the content of the cross-linking agent in the pressure-sensitive adhesive layer is determined in the pressure-sensitive adhesive layer. From the viewpoint of realizing sufficient adhesion reliability to the adherend, it is preferably 0.001 part by weight or more, more preferably 0.01 part by weight or more with respect to 100 parts by weight of the pressure-sensitive adhesive or acrylic polymer in the pressure-sensitive adhesive layer. It is. In addition, the content of the cross-linking agent in the pressure-sensitive adhesive layer is suitable for the pressure-sensitive adhesive or acrylic polymer 100 in the pressure-sensitive adhesive layer from the viewpoint of realizing an appropriate flexibility in the pressure-sensitive adhesive layer and realizing a good pressure-sensitive adhesive force. Preferably it is 10 weight part or less with respect to a weight part, More preferably, it is 5 weight part or less.

  The pressure-sensitive adhesive layers 11 and 12 are respectively a crosslinking accelerator, a tackifier resin, an anti-aging agent, a filler, a colorant such as a pigment or a dye, an antioxidant, a chain transfer agent, a plasticizer, and a softening as necessary. You may further contain additives, such as an agent, surfactant, and an antistatic agent. Examples of the tackifying resin include rosin derivatives, polyterpene resins, petroleum resins, and oil-soluble phenols.

  The thickness of the pressure-sensitive adhesive layer 11 is preferably 5 μm or more, more preferably 10 μm or more, more preferably 15 μm, from the viewpoint of realizing sufficient adhesive force on the adherend on the pressure-sensitive adhesive layer 11 side in the pressure-sensitive adhesive tape X. That's it. From the viewpoint of ease of formation, the thickness of the pressure-sensitive adhesive layer 11 is preferably 1000 μm or less, more preferably 900 μm or less, and more preferably 800 μm or less.

  The thickness of the pressure-sensitive adhesive layer 12 is preferably 5 μm or more, more preferably 10 μm or more, and more preferably 15 μm from the viewpoint of realizing sufficient adhesive force to the adherend on the pressure-sensitive adhesive layer 12 side in the pressure-sensitive adhesive tape X. That's it. From the viewpoint of ease of formation, the thickness of the pressure-sensitive adhesive layer 11 is preferably 1000 μm or less, more preferably 900 μm or less, and more preferably 800 μm or less.

  In the adhesive tape X having the laminated structure including the base material 10 and the adhesive layers 11 and 12 as described above, the Elmendorf tear strength in the base material width direction is 0.5 N or less, and the Elmendorf tear in the base material machine direction. The strength is 1N or more. The Elmendorf tear strength in the substrate width direction of the adhesive tape X is preferably 0.45 N or less, more preferably 0.4 N or less, and more preferably 0.3 N or less. The Elmendorf tear strength of the adhesive tape X in the substrate machine direction is preferably 1.1 N or more, more preferably 1.3 N or more, more preferably 1.5 N or more. The Elmendorf tear strength is a value measured according to JIS K 7128-2.

  The haze in the thickness direction of the optical adhesive tape X is preferably 3% or less, more preferably 2.5% or less, more preferably 2% or less, more preferably 1.5% or less, and more preferably 1% or less. The haze is a value measured according to JIS K 7136. For the adhesive tape X, the total light transmittance in the visible light wavelength region is, for example, 85% or more. The total light transmittance is a value measured in accordance with JIS K 7361-1.

  The adhesive tape X may be provided with a release liner (separator) so as to cover the adhesive surface 11 a of the adhesive layer 11. The adhesive tape X may be provided with a release liner (separator) so as to cover the adhesive surface 12 a of the adhesive layer 12. The release liner is an element for protecting the adhesive layers 11 and 12 of the adhesive tape X from being exposed, and is peeled off from the adhesive tape X when the adhesive tape X is bonded to an adherend. Examples of the release liner include a substrate having a release treatment layer, a low adhesion substrate made of a fluoropolymer, and a low adhesion substrate made of a nonpolar polymer. The surface of the release liner may be subjected to mold release treatment, antifouling treatment, or antistatic treatment. The thickness of the release liner is, for example, 5 to 200 μm. Specifically, the adhesive tape X may take the form of a sheet with a release liner that covers the adhesive surfaces 11a and 12a of the adhesive layers 11 and 12, and the adhesive tape X and the release liner are alternately arranged. As such, it may take a form wound in a roll with a release liner.

  The pressure-sensitive adhesive tape X having the above-described configuration can be manufactured, for example, by forming the pressure-sensitive adhesive layers 11 and 12 and then bonding the pressure-sensitive adhesive layers 11 and 12 to the substrate 10 respectively. The pressure-sensitive adhesive layer 11 is formed by, for example, applying a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 11 on a predetermined release liner to form a pressure-sensitive adhesive composition layer, and further releasing a liner on the pressure-sensitive adhesive composition layer. Are laminated, and the pressure-sensitive adhesive composition is cured between the release liners. On the other hand, the pressure-sensitive adhesive layer 12 is formed by, for example, applying a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 12 on a predetermined release liner to form a pressure-sensitive adhesive composition layer, and further forming the pressure-sensitive adhesive composition layer on the pressure-sensitive adhesive composition layer. It can be formed by laminating release liners and curing the pressure-sensitive adhesive composition between the release liners.

  Examples of the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 12 include a pressure-sensitive adhesive composition that can be cured by a polymerization reaction that proceeds by irradiation with active energy rays. Used. That is, the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive layer 12 is, for example, a cured product of an active energy ray-curable pressure-sensitive adhesive composition. The active energy ray-curable pressure-sensitive adhesive composition for forming an acrylic pressure-sensitive adhesive layer contains at least a monomer, an oligomer, and a photopolymerization initiator for forming an acrylic polymer. The monomer and oligomer in the composition can be used as a so-called partial polymer of a monomer mixture having a predetermined composition for forming an acrylic polymer. Moreover, the said adhesive composition may contain the other component employ | adopted as needed as a component of the adhesive layer formed. Examples of the active energy ray irradiated to the active energy ray-curable pressure-sensitive adhesive composition for curing the pressure-sensitive adhesive layer include ultraviolet rays, α rays, β rays, γ rays, neutron rays, and electron beams. Preferably, ultraviolet rays are used. In the active energy ray-curable pressure-sensitive adhesive composition for forming an acrylic pressure-sensitive adhesive layer that has been irradiated with an active energy ray, an initiation reaction occurs through the activation of the photopolymerization initiator, leading to the formation of an acrylic polymer. The polymerization reaction proceeds. When active energy ray irradiation such as ultraviolet irradiation is adopted as a curing method for the curable pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer, even when the coating film of the pressure-sensitive adhesive composition is relatively thick, it is cured appropriately. It is easy to obtain a pressure-sensitive adhesive layer. Therefore, the configuration that the pressure-sensitive adhesive layer 11 is a cured product of the active energy ray-curable pressure-sensitive adhesive composition is suitable for realizing the pressure-sensitive adhesive layer 11 that is sufficiently cured even if it is relatively thick. The configuration in which the pressure-sensitive adhesive layer 12 is a cured product of the active energy ray-curable pressure-sensitive adhesive composition is suitable for realizing a sufficiently hardened pressure-sensitive adhesive layer 12 even if it is relatively thick.

  Examples of the photopolymerization initiator include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, and photoactive oxime-based light. Examples include a polymerization initiator, a benzoin photopolymerization initiator, a benzyl photopolymerization initiator, a benzophenone photopolymerization initiator, a ketal photopolymerization initiator, and a thioxanthone photopolymerization initiator. Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-1,2-diphenylethane-1-one. Can be mentioned. As the acetophenone photopolymerization initiator, for example, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone (α-hydroxycyclohexyl phenyl ketone), 4-phenoxydichloroacetophenone , And 4- (t-butyl) dichloroacetophenone. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone and 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one. . Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, and polyvinylbenzophenone. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. The content of the photopolymerization initiator in the active energy ray-curable pressure-sensitive adhesive composition is, for example, 0.01 to 3% by weight.

  The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 11 and / or the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer 12 includes a solvent-type pressure-sensitive adhesive that already contains an acrylic polymer as a pressure-sensitive adhesive and can be cured by, for example, heat drying. A composition or an emulsion-type pressure-sensitive adhesive composition may be used. The said composition may contain the other component employ | adopted as needed as a component of the adhesive layer formed. The acrylic polymer in the pressure-sensitive adhesive composition can be obtained by polymerizing raw material monomer components for forming an acrylic polymer. Examples of the polymerization technique include solution polymerization, emulsion polymerization, and bulk polymerization. When performing solution polymerization, for example, aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, esters, and ketones can be used as a solvent. Examples of the aromatic hydrocarbon solvent include toluene and benzene. Examples of the aliphatic hydrocarbon solvent include n-hexane and n-heptane. Examples of the alicyclic hydrocarbon solvents include cyclohexane and methylcyclohexane. Examples of the solvent for esters include ethyl acetate and n-butyl acetate. Examples of the ketone solvent include methyl ethyl ketone and methyl isobutyl ketone. In the solution polymerization, one type of solvent may be used, or two or more types of solvents may be used.

  A polymerization initiator can be used when polymerizing the raw material monomer component to obtain an acrylic polymer. Depending on the type of the polymerization reaction, for example, a photopolymerization initiator or a thermal polymerization initiator can be used. In the polymerization, one type of polymerization initiator may be used, or two or more types of polymerization initiators may be used.

  Examples of the photopolymerization initiator include the benzoin ether photopolymerization initiator, the acetophenone photopolymerization initiator, the α-ketol photopolymerization initiator, the aromatic sulfonyl chloride photopolymerization initiator, and the photoactive oxime light. Examples include a polymerization initiator, a benzoin photopolymerization initiator, a benzyl photopolymerization initiator, a benzophenone photopolymerization initiator, a ketal photopolymerization initiator, and a thioxanthone photopolymerization initiator. The usage-amount of a photoinitiator is 0.01-3 weight part with respect to monomer component whole quantity (100 weight part), for example.

  Examples of the thermal polymerization initiator include an azo polymerization initiator, a peroxide polymerization initiator, and a redox polymerization initiator. Examples of the azo polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, and 2,2′-azobis (2-methylpropionic acid) dimethyl. And 4,4′-azobis-4-cyanovaleric acid. Examples of the peroxide-based polymerization initiator include benzoyl peroxide and tert-butyl permaleate. The usage-amount of a thermal-polymerization initiator is 0.05-0.3 weight part with respect to monomer component whole quantity (100 weight part), for example.

  In the polymerization for obtaining the acrylic polymer, a chain transfer agent can be used to adjust the molecular weight of the acrylic polymer. Examples of the chain transfer agent include α-thioglycerol, 2-mercaptoethanol, 2,3-dimercapto-1-propanol, octyl mercaptan, t-nonyl mercaptan, dodecyl mercaptan (lauryl mercaptan), t-dodecyl mercaptan, glycidyl mercaptan. Thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, thio And decyl glycolate and dodecyl thioglycolate. As the chain transfer agent, one type of chain transfer agent may be used, or two or more types of chain transfer agents may be used. In this embodiment, α-thioglycerol is preferably used as the chain transfer agent. The amount of the chain transfer agent used is, for example, 0.01 to 0.5 parts by weight with respect to the total amount of monomer components (100 parts by weight) for obtaining an acrylic polymer.

  When the pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer, such as an active energy ray-curable pressure-sensitive adhesive composition, a solvent-type pressure-sensitive adhesive composition, or an emulsion-type pressure-sensitive adhesive composition, contains the above-mentioned acrylic oligomer, the oligomer Can be obtained by polymerizing raw material monomer components having a predetermined composition. Examples of the polymerization technique include solution polymerization, emulsion polymerization, and bulk polymerization. Examples of the solvent for the solution polymerization include those described above as the solvent that can be used for the solution polymerization for obtaining the acrylic polymer. In the solution polymerization, one type of solvent may be used, or two or more types of solvents may be used. Moreover, when polymerizing a raw material monomer component in order to obtain the said oligomer, a polymerization initiator can be used. Examples of the polymerization initiator include the above-described photopolymerization initiator and thermal polymerization initiator as a polymerization initiator that can be used for polymerization for obtaining an acrylic polymer. In the polymerization, one type of polymerization initiator may be used, or two or more types of polymerization initiators may be used.

  For example, the base material 10 which the adhesive tape X manufactured as mentioned above has is a polyester-type base material as mentioned above. Such a configuration is suitable for enjoying various characteristics such as heat resistance, transparency, and dimensional stability that are easily developed in the polyester base material, and in the adhesive tape X.

  Moreover, the base material 10 which the adhesive tape X has is a width direction uniaxially stretched polyester base material as mentioned above. As described above, the thickness of the substrate 10 is 75 μm or more, and preferably 80 μm or more. As described above, the thickness of the substrate 10 is, for example, 150 μm or less, and preferably 125 μm or less. The tear strength such as Elmendorf tear strength in the double-sided adhesive tape is strongly governed by the mechanical properties of the base material. In these structures, the Elmendorf tear strength in the base material width direction of the adhesive tape X is 0.5 N or less. It is suitable for realizing the above configuration in which the Elmendorf tear strength in the substrate machine direction is 1 N or more.

  In addition, the Elmendorf tear strength in the substrate width direction of the adhesive tape X is 0.5 N or less, preferably 0.45 N or less, more preferably 0.4 N or less, more preferably 0.3 N, as described above. It is as follows. At the same time, the Elmendorf tear strength in the machine direction of the base material in the adhesive tape X is 1N or more, preferably 1.1N or more, more preferably 1.3N or more, more preferably 1.5N or more. is there. These structures are suitable for realizing good hand cutting properties in the width direction of the base material in the adhesive tape X, in which the Elmendorf tear strength is relatively significantly lower than 0.5N. And the structure that Elmendorf tear strength is 2 times or more of a base-material width direction in a base-material machine direction is suitable for improving the directivity regarding the tear to the base-material width direction in the adhesive tape X. Therefore, when the adhesive tape X is bonded to the adherend, the configuration does not tear the adhesive tape X from the adherend by applying a peeling force to the substrate machine direction of the adhesive tape X. It is suitable for making it peel appropriately. Specifically, after the adhesive tape X is bonded to the adherend, it is peeled once and bonded again (rework work), and the adhesive tape X is applied by applying a peeling force in the substrate machine direction. It is suitable for appropriately peeling the adhesive tape X from the body without tearing. Optical double-sided pressure-sensitive adhesive tapes that are easily torn in the substrate machine direction in addition to the substrate width direction tend to tear when peeled during rework work, and tend to be difficult to peel off properly. The optical double-sided pressure-sensitive adhesive tape in which tearing has occurred cannot be used for re-bonding. On the other hand, since the adhesive tape X has a substrate machine direction Elmendorf tear strength that is sufficiently larger than the substrate width direction Elmendorf tear strength suitable for realizing good hand cutting properties in the substrate width direction, In the rework operation, a peeling force is applied in the direction of the substrate machine so that it can be properly peeled without tearing.

  As described above, the pressure-sensitive adhesive tape X is suitable for realizing both good hand cutting properties and high reworkability while having a polyester base material.

  As described above, the in-plane retardation of the substrate 10 of the adhesive tape X is preferably 1500 nm or more, more preferably 3000 nm or more, and more preferably 6000 nm or more. In such a configuration, when the adhesive tape X is provided so as to fill a space between the transparent cover that forms the forefront of the display screen in the liquid crystal display device and the liquid crystal panel in the device, for example, polarized light such as polarized sunglasses This is suitable for suppressing the occurrence of a so-called blackout phenomenon when the display screen is viewed through the lens with a function. Further, when the adhesive tape X is provided so as to fill the space between the transparent cover and the liquid crystal panel in the liquid crystal display device as the in-plane retardation of the substrate 10 increases, for example, with a polarizing function such as polarized sunglasses When the display screen is viewed through the lens, a so-called rainbow unevenness phenomenon tends to be suppressed.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[Production example of acrylic oligomer]
In a reaction vessel, 60 parts by weight of dicyclopentanyl methacrylate (DCPMA), 40 parts by weight of methyl methacrylate (MMA), 3.5 parts by weight of α-thioglycerol as a chain transfer agent, and a polymerization solvent A mixture containing 100 parts by weight of toluene was stirred at 70 ° C. for 1 hour under a nitrogen atmosphere. Next, 0.2 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator was added to the mixture in the reaction vessel to prepare a reaction solution, and the reaction was performed at 70 ° C. for 2 hours. Subsequently, the reaction was performed at 80 ° C. for 2 hours. Thereafter, the reaction solution in the reaction vessel was placed in a temperature atmosphere of 130 ° C., and toluene, chain transfer agent, and unreacted monomer were removed by drying from the reaction solution. Thereby, a solid acrylic oligomer was obtained. The acrylic oligomer had a weight average molecular weight (Mw) of 5.1 × 10 ³ .

[Preparation Example of Acrylic Adhesive Composition C1]
A monomer mixture containing 78 parts by weight of 2-ethylhexyl acrylate (2EHA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP) and 4 parts by weight of 2-hydroxyethyl acrylate (HEA) 0.035 parts by weight of a photopolymerization initiator (trade name “Irgacure 651”, manufactured by BASF) and 0.035 parts by weight of a second photopolymerization initiator (trade name “Irgacure 184”, manufactured by BASF) were added. Thereafter, the mixture was irradiated with ultraviolet rays using an ultraviolet irradiation device until the viscosity of the mixture reached about 20 Pa · s while measuring the viscosity using a viscosity measuring device. In the viscosity measurement, the rotor rotation speed of the apparatus was 10 rpm, and the measurement temperature was 30 ° C. As a result, a prepolymer composition (containing a monomer component that did not undergo a polymerization reaction) was obtained as a partial polymer obtained by polymerizing a part of the monomer component in the mixture. Then, 100 parts by weight of this prepolymer composition, 11.8 parts by weight of the above-mentioned acrylic oligomer, 17.6 parts by weight of 2-hydroxyethyl acrylate (HEA), and 1,6-hexanediol diacrylate (HDDA) ) 0.294 parts by weight and 0.353 parts by weight of a silane coupling agent (trade name “KBM-403”, manufactured by Shin-Etsu Chemical Co., Ltd.) are mixed to prepare an acrylic pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive composition). Product C1) was obtained.

[Preparation Example of Acrylic Adhesive Composition C2]
In a flask (reaction vessel) equipped with a reflux condenser, a nitrogen gas inlet tube, a stirrer, and a thermometer, 100 parts by weight of n-butyl acrylate (BA), 5 parts by weight of acrylic acid (AA), and acrylic acid 0.075 part by weight of 2-hydroxyethyl (HEA), 0.2 part by weight of benzoyl peroxide (trade name “Nyper BW”, manufactured by NOF Corporation) as a polymerization initiator, and ethyl acetate 205 as a polymerization solvent The mixture containing 4 parts by weight was reacted at 63 ° C. for 4 hours with gentle stirring under a nitrogen atmosphere. Thereby, a solution (acrylic polymer solution) containing an acrylic polymer at a concentration of about 35% by weight was obtained. Then, after the acrylic polymer solution is diluted with ethyl acetate so that the acrylic polymer concentration becomes 29% by weight, 0.6 parts by weight of trimethylol is added to the acrylic polymer solution with respect to 100 parts by weight of the acrylic polymer. Propane / tolylene diisocyanate adduct (trade name “Coronate L”, manufactured by Nippon Polyurethane Industry Co., Ltd.) and 0.075 parts by weight of silane coupling agent (trade name “KBM-403”, manufactured by Shin-Etsu Chemical Co., Ltd.) And mixing at 25 ° C. for about 1 minute to obtain a solvent-type acrylic pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive composition C2).

[Example 1]
<Formation of first adhesive layer>
On the polyethylene terephthalate (PET) release liner (thickness 125 μm, manufactured by Nitto Denko Corporation), the above-mentioned acrylic pressure-sensitive adhesive composition C1 was applied to form a pressure-sensitive adhesive composition layer. Next, a PET release liner (thickness 125 μm, manufactured by Nitto Denko Corporation) was further laminated on the pressure-sensitive adhesive composition layer, and the pressure-sensitive adhesive composition layer was covered to block oxygen. Thus, the laminated body (laminated body L1 ') which has a laminated structure of [release liner / adhesive composition layer / release liner] was obtained. Next, the laminate L1 ′ was irradiated with ultraviolet rays having an illuminance of 3 mW / cm ² for 300 seconds from the side of one release liner using a black light (manufactured by Toshiba Corporation). Thus, the pressure-sensitive adhesive composition layer of the laminate L1 ′ is cured to form a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer), and a laminated configuration of [release liner / pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) / release liner]. The laminated body (laminate L1) which has was obtained. The thickness of the 1st adhesive layer in the laminated body L1 is 100 micrometers.

<Formation of second adhesive layer>
On the PET release liner (thickness 125 μm, manufactured by Nitto Denko Corporation), the above-mentioned acrylic pressure-sensitive adhesive composition C2 was applied to form a pressure-sensitive adhesive composition layer. Next, a PET release liner (thickness 125 μm, manufactured by Nitto Denko Corporation) was further laminated on the pressure-sensitive adhesive composition layer, and the pressure-sensitive adhesive composition layer was covered to block oxygen. In this way, a laminate (laminate L2 ′) having a laminate configuration of [release liner / adhesive composition layer / release liner] was obtained. Next, the laminate L2 ′ was irradiated with ultraviolet rays having an illuminance of 3 mW / cm ² for 300 seconds from the one release liner side using a black light (manufactured by Toshiba Corporation). Thereby, the pressure-sensitive adhesive composition layer of the laminate L2 ′ is cured to form a pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer), and a laminated structure of [release liner / pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) / release liner] is obtained. The laminated body (laminate L2) which has was obtained. The thickness of the 2nd adhesive layer in the laminated body L2 is 500 micrometers.

<Production of optical double-sided adhesive tape>
A film (film F ₁ ) obtained by corona treatment on both sides of a polyethylene terephthalate film (trade name “Cosmo Shine SRF”, in-plane retardation 8400, manufactured by Toyobo Co., Ltd.) having a thickness of 80 μm is prepared, and the above-described lamination is performed. After peeling one release liner from the body L1 (release liner / first pressure-sensitive adhesive layer / release liner), the first pressure-sensitive adhesive layer with a one-side release liner is passed through the surface of the first pressure-sensitive adhesive layer exposed by the peeling. bonded to one surface of the film F _1. As a result, a laminate having a laminate configuration of [release liner / first pressure-sensitive adhesive layer / film F ₁ ] was obtained. Next, after peeling one release liner from the laminate L2 (release liner / second pressure-sensitive adhesive layer / release liner), a one-side release liner is provided via the surface of the second pressure-sensitive adhesive layer exposed by the peeling. the second pressure-sensitive adhesive layer was bonded to the other surface of the film F _1. As described above, laminated structure of [release liner / first pressure-sensitive adhesive layer (thickness 100 μm) / substrate F ₁ (thickness 80 μm) / second pressure-sensitive adhesive layer (thickness 500 μm) / release liner] An optical double-sided pressure-sensitive adhesive tape having the above was prepared. The thickness of the optical double-sided adhesive tape of Example 1 excluding the thickness of the release liner is 680 μm.

[Example 2]
As a base material for optical double-sided adhesive tape, a polyethylene terephthalate film with a thickness of 80 μm (“Cosmo Shine SRF” easy-adhesion treatment layer is replaced with an easy-adhesion treatment layer for hard coat applications, in-plane retardation 8400, Toyobo Co., Ltd. The optical double-sided pressure-sensitive adhesive tape of Example 2 was used in the same manner as Example 1 except that a film (film F ₂ ) obtained by corona treatment on both sides of the company was used instead of film F _1. Produced. The thickness of the optical double-sided adhesive tape of Example 2 excluding the thickness of the release liner is 680 μm.

Example 3
An optical double-sided pressure-sensitive adhesive tape of Example 3 was produced in the same manner as in Example 1 except that the thickness of the second pressure-sensitive adhesive layer was changed to 100 μm instead of 500 μm. The thickness of the optical double-sided adhesive tape of Example 3 excluding the thickness of the release liner is 280 μm.

Example 4
The acrylic pressure-sensitive adhesive composition C2 is applied to one side of the film F ₁ and then dried and cured by heating at 130 ° C. for 60 seconds to form a pressure-sensitive adhesive layer (first pressure-sensitive adhesive) having a thickness of 12 μm on the film F _1. Layer). Next, a PET release liner (thickness 125 μm, manufactured by Nitto Denko Corporation) was bonded to the surface of the pressure-sensitive adhesive layer. This obtained the laminated body (laminated body L3) which has a laminated structure of [release liner / adhesive layer (1st adhesive layer) / release liner]. On the other hand, the acrylic pressure-sensitive adhesive composition C2 is applied to one side of a PET release liner (thickness 125 μm, manufactured by Nitto Denko Corporation), and then heated and dried at 130 ° C. for 60 seconds to be cured. A pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) having a thickness of 12 μm was formed thereon. Then, the laminate L3 of the bonded through the film F ₁ side surface to the surface of the adhesive layer. As described above, a laminated structure of [release liner / first pressure-sensitive adhesive layer (thickness 12 μm) / substrate film F ₁ (thickness 80 μm) / second pressure-sensitive adhesive layer (thickness 12 μm) / release liner] An optical double-sided pressure-sensitive adhesive tape of Example 4 was prepared. The thickness of the optical double-sided adhesive tape of Example 4 excluding the thickness of the release liner is 104 μm.

[Comparative Example 1]
A film (film F ₃ ) obtained by subjecting both surfaces of a 75 μm thick polyethylene terephthalate film (trade name “XD500P”, in-plane retardation 3000, manufactured by Toray Industries, Inc.) to corona treatment as a base material for the optical double-sided adhesive tape. ) Was used in place of the film F ₁ and the thickness of the second pressure-sensitive adhesive layer was changed to 100 μm instead of 500 μm. A tape was prepared. The thickness of the optical double-sided adhesive tape of Comparative Example 1 excluding the thickness of the release liner is 275 μm.

[Comparative Example 2]
Except for using the film F ₃ in place of the film F ₁ as a double-sided pressure-sensitive adhesive tape base material for optical in the same manner as in Example 4, to prepare a double-sided adhesive tape for optical Comparative Example 2. The thickness of the optical double-sided pressure-sensitive adhesive tape of Comparative Example 2 excluding the thickness of the release liner is 104 μm.

<Elmendorf tear strength>
For each sample piece (60 mm × 75 mm) cut out from the optical double-sided adhesive tapes of Examples and Comparative Examples, an Elmendorf tear strength measuring device (trade name “Elmendorf Tear Tester”, manufactured by Tester Sangyo Co., Ltd.) is used. The Elmendorf tear strength (N) in the width direction (TD) of the tape base material and the Elmendorf tear strength (N) in the machine direction (MD) of the tape base material were measured. This measurement was performed according to JIS K 7128-2. The sample piece subjected to the measurement is previously provided with a 20 mm long cut extending from the end in the measurement direction (TD or MD). In this measurement, the resistance force to the tear load applied to the sample piece by the apparatus is measured so that the incision further extends. Moreover, the measurement maximum value of the said apparatus used for this measurement is 1N. The results of this measurement are listed in Table 1.

<Hand cutting ability>
About each double-sided adhesive tape for optics of an Example and a comparative example, the hand cutting property of the base-material width direction was investigated. Specifically, an attempt was made to tear the optical double-sided pressure-sensitive adhesive tape from which both release liners had been peeled by manual work in the substrate width direction. In the manual inspection, the hand tearability was evaluated as good (◯) when it was easily torn, and the hand tearability was evaluated as poor (×) when it was not tearable. The results are listed in Table 1.

<Haze>
About each optical double-sided adhesive tape of an Example and a comparative example, using a haze meter HM-150 type (made by Murakami Color Research Laboratory Co., Ltd.), haze (%) in accordance with the method prescribed in JIS K 7136 Was measured. In this measurement, both the release liners were peeled off and both sides of the optical sheet were attached to a slide glass (trade name “Slide Glass S1112”, thickness 1.0 to 1.2 mm, manufactured by Matsunami Glass Industrial Co., Ltd.). It performed about the adhesive tape. The results are listed in Table 1.

[Evaluation]
In each of the optical double-sided pressure-sensitive adhesive tapes of Examples 1 to 4 having the configuration of the present invention, good hand cutting properties were realized. On the other hand, in the optical double-sided pressure-sensitive adhesive tapes of Comparative Examples 1 and 2, neither of them could be torn by hand in the width direction of the base material, and good hand cutting properties were not realized.

X Adhesive tape (Double-sided optical adhesive tape)
10 base material 11 pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer)
12 Adhesive layer (second adhesive layer)

Claims (4)

Having a laminated structure including a first pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer, and a transparent substrate between the first and second pressure-sensitive adhesive layers;
The transparent substrate is a substrate width direction uniaxially stretched polyester-based substrate and has a thickness of 75 μm or more,
An optical double-sided pressure-sensitive adhesive tape having an Elmendorf tear strength in the substrate width direction of 0.5 N or less and an Elmendorf tear strength in the substrate machine direction of 1 N or more.   2. The optical double-sided pressure-sensitive adhesive tape according to claim 1, wherein the first pressure-sensitive adhesive layer has a thickness of 5 μm or more, and the second pressure-sensitive adhesive layer has a thickness of 5 μm or more.   The optical double-sided pressure-sensitive adhesive tape according to claim 1 or 2, wherein the haze is 3% or less.   The said adhesive layer contains at least 1 sort (s) selected from the group which consists of an acrylic adhesive, a urethane type adhesive, a silicone type adhesive, and a rubber-type adhesive, or any one of Claim 1 to 3 Optical double-sided adhesive tape.

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