JP2009263568A - Adhesive sheet and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive sheet which is excellent in handling properties and is produced in high yield. <P>SOLUTION: The adhesive sheet includes a first base material 10, a second base material 20, and an adhesive layer 30 in this order. Absorbance (A<SB>2</SB>) of the second base material 20 is made larger than that (A<SB>1</SB>) of the first base material 10. It is preferable that a difference (A<SB>2</SB>-A<SB>1</SB>) between the absorbance (A<SB>2</SB>) of the second base material 20 and that (A<SB>1</SB>) of the first base material 10 is ≥0.2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adhesive sheet and a method for producing the same. In more detail, it is related with the adhesive sheet | seat used for image display apparatuses, such as a liquid crystal display device, and its manufacturing method.

  Glass substrates are used in image display devices such as liquid crystal display devices, plasma displays, and organic electroluminescence displays. In order to prevent the glass substrate from being broken by an external impact, it is disclosed that an impact absorbing layer (adhesive layer) is provided on the viewing side of the glass substrate (see Patent Document 1).

  In mobile devices such as cellular phones, a protective layer made of plastic or the like is usually provided on the viewing side of the display via an air layer. However, there is a problem in that visibility is reduced due to reflection generated at the interface between the protective layer and the air layer and at the interface between the air layer and the display. Therefore, the impact absorbing layer is used in place of the air layer for the purpose of improving impact resistance and visibility and reducing the thickness. Usually, the shock absorbing layer is cut into individual pieces from a large-sized pressure-sensitive adhesive sheet according to the size of the display to be applied, and bonded to each display.

In general, the step of cutting the pressure-sensitive adhesive sheet into pieces and the step of bonding the piece-like pressure-sensitive adhesive sheet to the display are performed at different locations. In this case, it is necessary to convey the cut | disconnected adhesive sheet to the place which performs a bonding process. When the pressure-sensitive adhesive sheet is completely cut in the cutting step (full cut), there is a problem in that the plurality of cut pressure-sensitive adhesive sheets cannot be used by being fused to each other during transportation. Therefore, a method (half cut) of cutting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet previously provided with the base material so that the base material is not completely cut by dicing or a Thomson blade can be considered. However, there is a problem that such cutting is difficult. Even if it can be cut, there is a problem that handling property at the time of cutting and use is poor, such as adhesive sticking to the blade, adjacent pressure-sensitive adhesive layers fused together after cutting. These problems can occur remarkably in a pressure-sensitive adhesive sheet including an impact absorbing layer that can have a thickness of several hundred microns in order to obtain sufficient impact resistance performance. On the other hand, cutting with high yield is also desired.
JP 2005-173462 A

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a pressure-sensitive adhesive sheet having excellent handling properties and excellent yield.

The pressure-sensitive adhesive sheet of the present invention has a first base material, a second base material, and a pressure-sensitive adhesive layer in this order, and the absorbance (A ₂ ) of the _second base material is the first base material. It is greater than the absorbance (A ₁ ) of the substrate.

In a preferred embodiment, the absorbance (A ₁ ) of the first base material is 0.7 or less.

In a preferred embodiment, the absorbance (A ₂ ) of the _second substrate is greater than 0.7.

In a preferred embodiment, the difference (A ₂ −A ₁ ) between the absorbance (A ₂ ) of the _second substrate and the absorbance (A ₁ ) of the _first substrate is 0.2 or more.

  In preferable embodiment, the thickness of the said 1st base material is 30-200 micrometers, and the thickness of the said 2nd base material is 20-100 micrometers.

  In a preferred embodiment, the first base material includes at least one resin selected from the group consisting of a polyolefin resin, a polystyrene resin, and a cycloolefin resin, and the second base material is a polyester-based resin. Resin and / or polycarbonate resin is included.

  In a preferred embodiment, the pressure-sensitive adhesive layer includes a shock absorbing layer.

  In preferable embodiment, it has further the optical element arrange | positioned between the said 2nd base material and the said adhesive layer.

  In a preferred embodiment, the optical element is a polarizing plate.

  In another aspect of the present invention, a method for producing an adhesive sheet is provided. The method for producing the pressure-sensitive adhesive sheet includes a step of cutting the pressure-sensitive adhesive sheet so that the first base material is not completely cut by irradiation with laser light.

  In preferable embodiment, a laser beam is irradiated from the opposite side to the said 1st base material.

In a preferred embodiment, the laser is a CO ₂ laser.

  In still another aspect of the present invention, a half-cut adhesive sheet is provided. This half-cut pressure-sensitive adhesive sheet is obtained by the above production method.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive sheet excellent in handling property and excellent in the yield can be provided.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

A. Overall Configuration FIG. 1A is a schematic cross-sectional view of an adhesive sheet 100 according to a preferred embodiment of the present invention. The pressure-sensitive adhesive sheet 100 includes a first base material 10, a second base material 20, and a pressure-sensitive adhesive layer 30 in this order. FIG. 1B is a schematic cross-sectional view of an adhesive sheet 100 ′ according to another preferred embodiment of the present invention. The pressure-sensitive adhesive sheet 100 ′ further includes an optical element 40 in addition to the first base material 10, the second base material 20, and the pressure-sensitive adhesive layer 30. In the present embodiment, the optical element 40 is disposed between the second base material 20 and the pressure-sensitive adhesive layer 30. The optical element 40 is preferably a polarizing plate.

  Although not shown, the pressure-sensitive adhesive sheet of the present invention may further have any appropriate layer (film). Specific examples include an optical compensation layer and a separator. The type, number, arrangement, and the like of the optical compensation layer can be appropriately selected depending on the purpose. A separator is typically arrange | positioned at the side in which the 2nd base material 20 of the adhesive layer 30 is not arrange | positioned. Each layer constituting the pressure-sensitive adhesive sheet can be laminated via any appropriate adhesive layer. Specific examples of the adhesive layer include a pressure-sensitive adhesive layer and an adhesive layer. Details of each layer will be described later.

  FIG. 2 is a schematic cross-sectional view of an adhesive sheet 200 according to still another preferred embodiment of the present invention. The first base material 10, a plurality of adhesive pieces 30 ′, 30 ′, 30 ′ arranged in parallel on one side of the first base material 10, and the first base material 10 and the adhesive piece 30 ′ And a second substrate 20 disposed therebetween. The first base material is integrally formed as a series. Thus, by providing a plurality of pressure-sensitive adhesive pieces on one side of the substrate, it is possible to excel in handling properties when laminated on a display. Furthermore, it can be excellent in yield. The pressure-sensitive adhesive sheet 200 is typically applied to the first base material so that the pressure-sensitive adhesive sheet 100 shown in FIG. 1A is irradiated with a laser beam so that the first base material is not completely cut. Thus, all the layers (second adhesive layer 20 and adhesive layer 30 in FIG. 2) arranged on the second substrate side are completely cut (half cut). Preferably, it cut | disconnects to such an extent that a cut | interruption enters a 1st base material a little. Here, in order to suitably perform half-cutting, laser light may be irradiated after a separator has been stuck on the pressure-sensitive adhesive layer 30 in advance. In this way, the second base material is completely cut, whereby the handling property can be further improved.

B. Substrate As described above, the pressure-sensitive adhesive sheet of the present invention has a first substrate and a second substrate. The absorbance (A ₂ ) of the second substrate is greater than the absorbance (A ₁ ) of the _first substrate. By providing the first base material and the second base material satisfying such a relationship, an adhesive sheet excellent in handling property and yield can be obtained. Specifically, when the adhesive sheet is cut by irradiating a laser beam, there is a problem that it is easy to be fully cut. By adopting such a configuration, the first substrate is completely cut. Can be suppressed, and half-cutting can be easily performed.

The difference (A ₂ −A ₁ ) between the absorbance (A ₂ ) of the _second substrate and the absorbance (A ₁ ) of the _first substrate is preferably 0.2 or more, more preferably 0.3 or more, Especially preferably, it is 0.5 or more. By satisfying such a relationship, the handling property and the yield can be further improved. In the present specification, “absorbance” refers to the absorbance per 100 μm in thickness with respect to the irradiated laser light. For example, when a CO ₂ laser is used, it means the absorbance per 100 μm thickness with respect to light having a wavelength of 10.6 μm. Hereinafter, each base material will be described.

B-1. First substrate The absorbance (A ₁ ) of the _first substrate is preferably 0.7 or less, more preferably 0.6 or less, and particularly preferably 0.4 or less. By having such absorbance (A ₁ ), it is possible to effectively suppress the first substrate from being completely cut by the laser beam, and half-cutting can be performed more easily.

  The thickness of the first substrate can be set to any appropriate value. Preferably it is 30-200 micrometers, More preferably, it is 40-150 micrometers, Most preferably, it is 50-120 micrometers. When the thickness is less than 30 μm, there is a risk of full cutting due to laser light irradiation. If it is thicker than 200 μm, there may be a problem in cost.

As long as the absorbance of the first substrate is smaller than the absorbance of the second substrate, the first substrate can be formed of any appropriate material depending on the wavelength of the irradiated laser beam or the like. For example, when a CO ₂ laser (wavelength 10.6 μm) is used, the first base material is preferably made of at least one resin selected from the group consisting of polyolefin resins, polystyrene resins and cycloolefin resins. Including. Typically, a base material (protective film) with an adhesive layer is used as the first base material.

  Examples of the polyolefin resin include polyethylene and polypropylene.

  The polystyrene resin is a general term for resins that are polymerized using a styrene monomer as a polymerization unit. Examples of the styrene monomer include styrene, α-methylstyrene, 2,4-dimethylstyrene, and the like. Polystyrene resins include polystyrene, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer, acrylonitrile / ethylene / styrene copolymer, styrene / maleimide copolymer, styrene / maleic anhydride copolymer, styrene. -A methyl methacrylate copolymer etc. are mentioned.

  The cycloolefin-based resin is a general term for resins that are polymerized using cycloolefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. The resin currently used is mentioned. Specific examples include a ring-opening (co) polymer of cycloolefin, an addition polymer of cycloolefin, and a copolymer of cycloolefin and α-olefin such as ethylene and propylene (typically a random copolymer). And graft modified products in which these are modified with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cycloolefin include norbornene monomers.

  Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. 2-Norbornene, 5-ethylidene-2-norbornene, and the like, polar substituents such as halogens thereof; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; 3-pentamer of cyclopentadiene, for example, 4,9: 5,8-dimethano-3a, 4 4a, 5,8,8a, 9,9a-octahydro-1H-benzoin 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene and the like. It is done.

B-2. Second substrate The absorbance (A ₂ ) of the _second substrate is preferably greater than 0.7, more preferably 0.8 or more, and particularly preferably 0.85 or more. By having such absorbance (A ₂ ), half-cutting can be performed more easily, and handling properties can be improved. Specifically, for example, when a plurality of pressure-sensitive adhesive pieces are provided on the first base material by forming a half-cut groove in a lattice shape on the pressure-sensitive adhesive sheet, the second base material is present. The pressure-sensitive adhesive piece can be easily peeled from the first base material together with the second base material (in this case, the second base material can function as a separator). Further, as shown in FIG. 1B, in the configuration in which the pressure-sensitive adhesive sheet includes an optical element (polarizing plate), the second substrate can function as a protective (scratch prevention) layer on the surface of the optical element.

  The thickness of the second substrate can be set to any appropriate value. Preferably it is 20-100 micrometers, More preferably, it is 25-80 micrometers, Most preferably, it is 30-60 micrometers. If it is thinner than 20 μm, the handling property at the time of use (peeling) may be inferior. If it is thicker than 100 μm, there may be a problem in cost.

As long as the absorbance of the second substrate is larger than that of the first substrate, the second substrate can be formed of any appropriate material depending on the wavelength of the laser light to be irradiated. For example, when a CO ₂ laser (wavelength 10.6 μm) is used, the second base material preferably includes a polyester-based resin and / or a polycarbonate-based resin.

  Examples of the polyester resin include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT).

  As the polycarbonate resin, an aromatic polycarbonate is preferably used. The aromatic polycarbonate can be typically obtained by a reaction between a carbonate precursor and an aromatic dihydric phenol compound. Specific examples of the carbonate precursor include phosgene, bischloroformate of dihydric phenols, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, dinaphthyl carbonate and the like. Can be mentioned. Among these, phosgene and diphenyl carbonate are preferable. Specific examples of the aromatic dihydric phenol compound include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and bis (4-hydroxyphenyl). ) Methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) butane, 2, 2-bis (4-hydroxy-3,5-dipropylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl And cyclohexane. You may use these individually or in combination of 2 or more types. Preferably, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are Used. In particular, it is preferable to use both 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

C. Adhesive layer (adhesive piece)
The pressure-sensitive adhesive layer (pressure-sensitive adhesive piece) can be formed of any appropriate pressure-sensitive adhesive. Moreover, the said adhesive layer (adhesive piece) has arbitrary appropriate structures, and may have a multilayered structure as needed. For example, the pressure-sensitive adhesive layer (pressure-sensitive adhesive piece) includes a shock absorbing layer. Even when the shock absorbing layer is included, by providing the first base material and the second base material that satisfy the above relationship, an adhesive sheet having excellent handling properties and a high yield can be obtained. . Hereinafter, the shock absorbing layer will be described.

C-1. Shock Absorbing Layer The shock absorbing layer can be formed of any appropriate pressure-sensitive adhesive. Specific examples include acrylic pressure-sensitive adhesives containing (meth) acrylic polymers. As a monomer which comprises a (meth) acrylic-type polymer, (meth) acrylic-acid alkylester is mentioned, for example. Specific examples of the (meth) acrylic acid alkyl ester include butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth) acrylate. , Isononyl (meth) acrylate, allyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.

  The (meth) acrylic polymer is preferably obtained by copolymerizing the above (meth) acrylic acid alkyl ester and a hydroxyl group-containing monomer. Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxy (meth) acrylate. Hydroxyalkyl (meth) acrylates such as hexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) -methyl acrylate , (Meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol and the like.

  Any suitable polymerization initiator may be used when the (meth) acrylic polymer is polymerized. Specific examples of the polymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α′-dimethylacetophenone, methoxyacetophenone, 2,2-dimethoxy- Acetophenone-based photopolymerization initiators such as 2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholinopropane-1 Etc.

  In the polymerization, a crosslinking agent may be added. As a crosslinking agent, polyfunctional (meth) acrylate is mentioned, for example. Specific examples of polyfunctional (meth) acrylates include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate , Pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, urethane (meth) ) Acrylate and the like.

The dynamic storage elastic modulus G ′ at 25 ° C. of the shock absorbing layer is preferably 1 × 10 ⁷ Pa or less, more preferably 1 × 10 ^{3 to} 7 × 10 ⁶ Pa. This is because an excellent shock absorbing ability can be obtained.

  The thickness of the shock absorbing layer is preferably 75 to 1000 μm, more preferably 100 to 600 μm. When the thickness is less than 75 μm, there is a possibility that sufficient impact absorbing ability cannot be obtained. On the other hand, when the thickness exceeds 1000 μm, a problem of visibility tends to occur.

  In addition, as the said shock absorption layer, you may employ | adopt the glass crack prevention adhesive layer of Unexamined-Japanese-Patent No. 2005-173462, for example.

C-2. Other Layers The pressure-sensitive adhesive layer (pressure-sensitive adhesive piece) may further include an undercoat layer disposed on one side or both sides of the shock absorbing layer. By providing the undercoat layer, the adhesive property of the shock absorbing layer to the adherend can be improved. Any appropriate material can be adopted as a material for forming the undercoat layer. As a specific example, an undercoat layer formed by crosslinking an adhesive composition will be described.

  The pressure-sensitive adhesive composition preferably contains a (meth) acrylic polymer and an isocyanate compound. The (meth) acrylic polymer refers to a polymer or copolymer synthesized from an acrylate monomer and / or a methacrylate monomer (referred to herein as (meth) acrylate). When the (meth) acrylic polymer is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be a coalescence. A preferred molecular arrangement state is a random copolymer.

  The (meth) acrylic polymer is obtained, for example, by homopolymerizing or copolymerizing alkyl (meth) acrylate. The alkyl group of the alkyl (meth) acrylate may be linear, branched or cyclic. Carbon number of the alkyl group of the alkyl (meth) acrylate is preferably about 1 to 18, more preferably 1 to 10.

  Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, t-butyl ( (Meth) acrylate, n-pentyl (meth) acrylate, iso-pentyl (meth) acrylate, n-hexyl (meth) acrylate, iso-hexyl (meth) acrylate, n-heptyl (meth) acrylate, iso-heptyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, n-nonyl (meth) acrylate, iso-nonyl (meth) acrylate, lauryl (meth) acrylate, Lil (meth) acrylate, cyclohexyl (meth) acrylate one bets. These can be used alone or in combination of two or more. When combining 2 or more types, the average carbon number of the alkyl group of the alkyl (meth) acrylate is preferably 3-9.

  The (meth) acrylic polymer may be a copolymer of the alkyl (meth) acrylate and a hydroxyl group-containing (meth) acrylate. In this case, the carbon number of the alkyl group of the alkyl (meth) acrylate is preferably 1 to 8, more preferably 2 to 8, particularly preferably 2 to 6, and most preferably 4 to 6. The alkyl group of the alkyl (meth) acrylate may be linear or branched.

  Specific examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3 -Hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 3-hydroxy-3-methylbutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 7-hydroxy Heptyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) Methyl acrylate. These can be used alone or in combination of two or more.

  The number of carbon atoms of the hydroxyalkyl group of the hydroxyl group-containing (meth) acrylate is preferably equal to or more than the number of carbon atoms of the alkyl group of the alkyl (meth) acrylate. Furthermore, the carbon number of the hydroxyalkyl group of the hydroxyl group-containing (meth) acrylate is preferably 2-8, more preferably 4-6. Thus, by adjusting the carbon number, the reactivity with an isocyanate compound described later can be excellent. For example, when 4-hydroxybutyl (meth) acrylate is used as the hydroxyl group-containing (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate or butyl is used as the alkyl (meth) acrylate. (Meth) acrylate is preferably used.

  The copolymerization amount of the hydroxyl group-containing (meth) acrylate is preferably 0.01 to 10 mol%, more preferably 0.1 to 10 mol%, particularly preferably 0.2 to 5 mol%, most preferably 0.00. 3 to 1.1 mol%. If it is the amount of copolymerization of the said range, the undercoat which is excellent in adhesiveness, durability, and stress relaxation property can be obtained.

  The (meth) acrylic polymer can be obtained by copolymerizing other components in addition to the alkyl (meth) acrylate and the hydroxyl group-containing (meth) acrylate. Other components include, but are not limited to, (meth) acrylic acid, benzyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate, (meth) acrylamide, acetic acid Vinyl, (meth) acrylonitrile and the like are preferably used. The copolymerization amount of the other components is preferably 100 parts by weight or less, more preferably 50 parts by weight or less with respect to 100 parts by weight of the alkyl (meth) acrylate.

  The weight average molecular weight (Mw) of the (meth) acrylic polymer is preferably 1 million or more, more preferably 1.2 million to 3 million, and particularly preferably 1.2 million to 2.5 million.

  Examples of the isocyanate compound include 2,4- (or 2,6-) tolylene diisocyanate, xylylene diisocyanate, 1,3-bis (isocyanate methyl) cyclohexane, hexamethylene diisocyanate, norbornene diisocyanate, chlorophenylene diisocyanate, tetramethylene. Isocyanate monomers such as diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, trimethylolpropane xylene diisocyanate, hydrogenated diphenylmethane diisocyanate; adduct isocyanate compounds obtained by adding these isocyanate monomers to polyhydric alcohols such as trimethylolpropane; isocyanurate compounds; burettes Type compound; furthermore any suitable polyether polyol All or a polyester polyol, acrylic polyol, polybutadiene polyol, isocyanate urethane prepolymer type obtained by addition reaction of polyisoprene polyol and the like, can be used in combination thereof either singly or in.

  A commercial item can be used as it is as the isocyanate compound. Examples of commercially available isocyanate compounds include Takenate series (trade name “D-110N, 500, 600, 700, etc.”) manufactured by Mitsui Takeda Chemical Co., Ltd. Name “L, MR, EH, HL, etc.”) and the like.

  An appropriate amount of the isocyanate compound may be set according to the purpose. For example, the blending amount is preferably 0.1 to 1.5 parts by weight, more preferably 0.3 to 1.0 parts by weight, particularly preferably 0.4 to 100 parts by weight of the (meth) acrylic polymer. -0.8 parts by weight. By setting the blending amount of the isocyanate compound in the above range, moderate stress relaxation properties and excellent thermal stability can be exhibited. Furthermore, the adhesiveness can be improved even in a harsh (high temperature, high humidity) environment.

  The pressure-sensitive adhesive composition may further contain various additives without departing from the object of the present invention. Examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, coupling agents, and additives. Examples thereof include a sticky agent and a pigment.

  An appropriate amount of the other additive may be set according to the purpose. The blending amount is preferably more than 0 and 5 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic polymer.

  The thickness of the undercoat layer can be set to any appropriate value. Preferably it is 1-50 micrometers, More preferably, it is 10-30 micrometers, Most preferably, it is 20-25 micrometers.

D. Polarizing plate The polarizing plate typically includes a polarizer and a protective film disposed on at least one side of the polarizer.

D-1. Polarizer Any appropriate polarizer may be adopted as the polarizer according to the purpose. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer uniaxially stretched by adsorbing iodine to a polyvinyl alcohol film can be produced by, for example, dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. By washing the polyvinyl alcohol film with water, not only can the surface of the polyvinyl alcohol film be cleaned and the anti-blocking agent can be washed, but also the effect of preventing unevenness such as uneven dyeing can be obtained by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

D-2. Protective film Any appropriate film that can be used as a protective film for a polarizing plate may be employed as the protective film. Specific examples of the material that is the main component of such a film include cellulose resins such as triacetylcellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, Examples thereof include transparent resins such as polysulfone, polystyrene, polynorbornene, polyolefin, acrylic, and acetate. In addition, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film may be an extruded product of the resin composition, for example. TAC, polyimide resin, polyvinyl alcohol resin, and glassy polymer are preferable, and TAC is more preferable.

  The polarizing plate may further have a surface treatment layer. The surface treatment layer is typically formed on the side of the protective film where the polarizer is not disposed. Specific examples of the surface treatment layer include a hard coat treatment layer, an antireflection treatment layer, an anti-sticking treatment layer, and an antiglare treatment layer.

E. Separator The separator typically includes a support base and a peelability-imparting layer disposed on at least one side of the support base (the side on which the pressure-sensitive adhesive layer is disposed). By appropriately selecting the type and coating amount of the release agent that forms the later-described peelability-imparting layer, the release force of the separator can be easily adjusted.

  Any appropriate plastic film can be adopted as the support substrate. Further, the support substrate may be a single layer of a plastic film or a laminate of plastic films. The plastic film can be formed of any appropriate material as long as it can function as a separator. Specific examples include nylons; halogen-containing polymers such as polyvinyl chloride; polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate (PET). Among these, a polyester film is preferable from the viewpoint of punching processability. Moreover, as a material of a support base material, the thing which does not contain the component used as a catalyst poison with respect to the said peelability provision layer (for example, silicone resin) is preferable. In addition, metal vapor deposition may be given to the surface of a support base material.

  The said peelability provision layer may be formed with arbitrary appropriate release agents. Specific examples include silicone-based release agents such as condensation-type and addition-type thermosetting silicone release agents, radiation-curable silicone release agents such as ultraviolet rays and electron beams, etc .; fluorine-containing esters of (meth) acrylic acid; Fluorine release agent containing an acrylic copolymer obtained by polymerizing an alkyl ester of (meth) acrylic acid having an alkyl group having 8 or less carbon atoms; having a long-chain alkyl group having 12 to 22 carbon atoms A long-chain alkyl release agent comprising an acrylic copolymer obtained by polymerizing an alkyl ester of (meth) acrylic acid and an alkyl ester of (meth) acrylic acid having an alkyl group having 8 or less carbon atoms ( JP-B-29-3144, JP-B-29-7333) and the like. Among these, a silicone release agent is preferable.

  As the peelability-imparting layer, for example, a release layer described in JP-A-2004-346093 may be employed.

  The thickness of the separator is typically about 15 to 100 μm, preferably about 30 to 100 μm.

F. Manufacturing method Arbitrary appropriate methods may be employ | adopted as a manufacturing method of the adhesive sheet of this invention. In the method for producing the pressure-sensitive adhesive sheet of the present invention, preferably, the pressure-sensitive adhesive sheet is cut so that the first base material is not completely cut by irradiation with laser light (for example, by laser ablation). Including (half cut). As shown in FIG. 2, the pressure-sensitive adhesive sheet (half-cut pressure-sensitive adhesive sheet) obtained by half-cutting has at least the first base material integrated as a series. Here, a part of the first substrate may be cut.

  Arbitrary appropriate methods may be employ | adopted as a laser beam irradiation method with respect to the said adhesive sheet. Specifically, irradiation may be performed from the first base material side of the pressure-sensitive adhesive sheet, or irradiation may be performed from the side opposite to the first base material (pressure-sensitive adhesive layer side). Preferably, the laser beam is irradiated from the opposite side of the first substrate.

  The laser light preferably includes light having a wavelength of at least 400 nm or less and / or 1.5 μm or more. More preferably, it contains light having a wavelength of 2 to 30 μm, particularly preferably 8 to 12 μm. This is because the material for forming each layer (film) including the pressure-sensitive adhesive layer can efficiently absorb laser light and can be cut well.

Any appropriate laser can be adopted as the laser. Specific examples include a gas laser such as a CO ₂ laser and an excimer laser; a solid laser such as a YAG laser; and a semiconductor laser. A CO ₂ laser is preferable. This is because the CO ₂ laser light can include light having the above-described preferable wavelength. The CO ₂ laser light preferably has a wavelength of 10.6 μm and 9.4 μm.

Arbitrary appropriate conditions can be employ | adopted for the irradiation conditions (focus output condition, moving speed, frequency | count) of a laser beam according to a cutting object, cutting depth, etc. The output condition is typically 10 to 800 W when a CO ₂ laser is used. Preferably it is 10-200W, More preferably, it is 50-150W. When the CO ₂ laser is used, the moving speed is typically 50 to 700 mm / second, preferably 100 to 500 mm / second. The number of times is typically 1 to 2 times.

G. Usage Method Any appropriate method can be adopted as the usage method of the impact-absorbing pressure-sensitive adhesive sheet of the present invention. Typically, there is a method in which the first base material and the second base material are peeled off and the peeled surface is attached to the surface of the optical element.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. Unless otherwise indicated, parts and% in the examples are based on weight.

The method for measuring the absorbance of each substrate used below is as follows.
Absorbance was measured by FT-IR method (Fourier transform infrared spectroscopy) and calculated by converting per 100 μm thickness.
Measuring device: Spectrum 2000 (manufactured by PerkinElmer)
Detector: MIRTGS
Beam splitter: KBr
Resolution: 4cm ^-1
Integration count: 16 times Measurement area: 4000-715 cm ⁻¹ (2.5-14 μm)
Measurement temperature: room temperature

[Example 1]
(Manufacture of shock absorbing layer)
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, an ultraviolet irradiation device and a stirring device, 83.6 parts of 2-ethylhexyl acrylate, 16.4 parts of 4-hydroxybutyl acrylate, 2,2 as a photopolymerization initiator 0.05 parts of dimethoxy-2-phenylacetophenone (“Irgacure-651” manufactured by Ciba Specialty Chemicals) and 1-hydroxycyclohexyl phenyl ketone (“Irgacure Ir-184” manufactured by Ciba Specialty Chemicals) 0 .05 parts was added and polymerized by irradiating with ultraviolet rays to obtain an acrylic polymer / monomer mixture having a polymerization rate of 13%. Next, with respect to 100 parts of this mixed solution, 0.2 part of trimethylpropane triacrylate as a crosslinking agent and 1-hydroxycyclohexyl phenyl ketone (“Irgacure Ir-184” manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator. ] 0.15 part was mixed and the coating liquid was obtained.
The coating solution obtained above was applied onto a separator (polyester film having a thickness of 75 μm, “PET Sepa MRN” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.), and the upper surface thereof was applied to the separator (“PET Sepa MRN”). And a laminate was obtained. The obtained laminate was photopolymerized by irradiating an ultraviolet ray of 2,000 mJ / cm ² with an ultraviolet lamp (high pressure mercury lamp), and then the upper side separator was peeled off, followed by drying at 150 ° C. for 50 minutes, A shock absorbing layer having a thickness of 200 μm was produced. The obtained impact-absorbing layer had a dynamic storage elastic modulus G ′ at 25 ° C. of 3 × 10 ⁴ Pa.

(Manufacture of undercoat layer)
In a four-necked flask equipped with a condenser, stirring blade and thermometer, 100 parts of butyl acrylate, 5 parts of acrylic acid, 0.1 part of 4-hydroxybutyl acrylate and 0.2 part of benzoyl peroxide are added to 100 parts of ethyl acetate. And the mixture was reacted at 60 ° C. for 7 hours to obtain an acrylic polymer solution having a solid content of 40%. To 100 parts of the solid content of this acrylic polymer solution, add 1 part of an isocyanate compound (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) with a solid content, and further add ethyl acetate, and a primer with a solid content of 30%. A solution was prepared. The obtained primer solution was applied on a substrate (polyester separator having a thickness of 38 μm) by a reverse roll coating method, dried at 150 ° C. for 3 minutes to volatilize the solvent, and an undercoat layer was produced. The thickness of the obtained undercoat layer after drying was 23 μm.

The undercoat layer obtained above and a separator (polyester film with a thickness of 75 μm, “PET Sepa MRF” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) are laminated in this order on the upper surface side of the impact absorbing layer obtained above. did.
Next, the separator (“PET Sepa MRN”) on the other side of the shock absorbing layer is peeled off, and a polarizing plate with a hard coat having a thickness of 215 μm (trade name “SEG1425DUHC” manufactured by Nitto Denko Corporation) on the peeled surface, The undercoat layer obtained in step 1 and the second substrate (“PET Sepa MRF” having a thickness of 38 μm) were laminated in this order. Here, the polarizing plate was laminated so that the hard coat surface of the polarizing plate was on the shock absorbing layer side.
Next, a polyethylene film with a pressure-sensitive adhesive layer (thickness 90 μm) (manufactured by Sekisui Chemical Co., Ltd., trade name “Protect Tape # 6281K-90”) was laminated on the second substrate.
Thus, separator (75 μm) / adhesive layer (undercoat layer 23 μm / impact absorbing layer 200 μm) / polarizing plate (215 μm) / adhesive layer (23 μm) / second substrate (thickness 38 μm) / adhesive layer The adhesive sheet which has the structure of the 1st base material (90 micrometers) containing this was produced.

[Example 2]
Adhesive as in Example 1 except that a 90 μm thick polypropylene film with an adhesive layer (manufactured by Nitto Denko Corporation, trade name “Dumplon Tape No375”) was laminated on the second substrate. A sheet was produced.

[Example 3]
A norbornene-based resin film (Optes Co., Ltd.) having a thickness of 40 μm is formed on the second substrate through a 12 μm-thick adhesive layer formed by the same method as in Example 1 by adjusting the concentration of the primer solution. Manufactured under the trade name “Zeonor ZF14-4”), a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1.

[Comparative Example 1]
Except that a PET film with a pressure-sensitive adhesive layer (thickness 17 μm) (thickness 55 μm) (manufactured by Fujimori Kogyo Co., Ltd., trade name “PPF900T”) was laminated on the second base material, in the same manner as in Example 1. An adhesive sheet was prepared.

[Comparative Example 2]
On a second substrate, a polycarbonate resin film having a thickness of 40 μm (Teijin Kasei Co., Ltd.) was passed through an adhesive layer having a thickness of 12 μm formed by the same method as in Example 1 by adjusting the concentration of the primer solution. ), A product name “TT-film”) was laminated in the same manner as in Example 1 except that an adhesive sheet was produced.

[Comparative Example 3]
As the second substrate, a norbornene-based resin film (trade name “Zeonor ZF14-100”, manufactured by Optes Co., Ltd.) having a thickness of 100 μm was used, and the primer solution was formed on the second substrate. The pressure-sensitive adhesive was the same as that of Example 1, except that “PET Sepa MRF” having a thickness of 38 μm was laminated through a pressure-sensitive adhesive layer having a thickness of 12 μm formed by the same method as in Example 1. A sheet was produced.

(Laser light irradiation)
The pressure-sensitive adhesive sheet obtained above was cut by irradiating laser light from the separator side with a CO ₂ laser (manufactured by Leitec, serial No. LT-00240). Irradiation was performed by focusing on the pressure-sensitive adhesive sheet polarizing plate part under the conditions of a wavelength of 10.6 μm, an output of 100 W, and a moving speed of 300 mm / second.

  Table 1 shows the cut state of the pressure-sensitive adhesive sheet (first base material) obtained in each Example and each Comparative Example together with the absorbance of the base material used.

The details of the cutting state of the first substrate in the table are as follows.
A: The cutting depth of the first base material after laser light irradiation was 20 μm or less. ○: The cutting depth of the first base material after laser light irradiation was deeper than 20 μm and 40 μm or less. After light irradiation, the first base material was completely cut and the adhesive sheet was fully cut. XX: After laser light irradiation, the second base material was not completely cut and the first base material was completely Not cut

As shown in Table 1, the pressure-sensitive adhesive sheets of Examples 1 to 3 were not fully cut by laser light irradiation, and the first base material was integrated integrally. Further, the cut surface was good, and the adjacent pressure-sensitive adhesive layers (impact absorbing layers) were not fused together. On the other hand, the pressure-sensitive adhesive sheets of Comparative Examples 1 and 2 were fully cut by laser light irradiation, and in Comparative Example 3, the second substrate was not completely cut. From the above, it can be said that by making the absorbance (A ₂ ) of the _second substrate larger than the absorbance (A ₁ ) of the first substrate, an adhesive sheet excellent in handling properties and yield can be obtained. .

  The pressure-sensitive adhesive sheet of the present invention is suitably used for image display devices such as a liquid crystal display device, a plasma display, and an organic electroluminescence display.

(A) is a schematic sectional drawing of the adhesive sheet by preferable embodiment of this invention, (b) is a schematic sectional drawing of the adhesive sheet by another preferable embodiment of this invention. It is a schematic sectional drawing of the adhesive sheet by another preferable embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st base material 20 2nd base material 30 Adhesive layer 30 'Adhesive piece 100 Adhesive sheet 100' Adhesive sheet 200 Adhesive sheet

Claims (13)

Having a first substrate, a second substrate, and an adhesive layer in this order,
The pressure-sensitive adhesive sheet, wherein the absorbance (A ₂ ) of the _second substrate is larger than the absorbance (A ₁ ) of the _first substrate. The pressure-sensitive adhesive sheet according to claim 1, wherein the first substrate has an absorbance (A ₁ ) of 0.7 or less. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the absorbance (A ₂ ) of the _second substrate is greater than 0.7. The difference (A ₂ -A ₁ ) between the absorbance (A ₂ ) of the _second substrate and the absorbance (A ₁ ) of the _first substrate is 0.2 or more, 4. The pressure-sensitive adhesive sheet according to crab. The thickness of the first substrate is 30 to 200 μm;
The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the thickness of the second base material is 20 to 100 µm. The first base material includes at least one resin selected from the group consisting of a polyolefin resin, a polystyrene resin, and a cycloolefin resin;
The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the second base material contains a polyester resin and / or a polycarbonate resin.   The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer includes a shock absorbing layer.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, further comprising an optical element disposed between the second base material and the pressure-sensitive adhesive layer.   The pressure-sensitive adhesive sheet according to claim 8, wherein the optical element is a polarizing plate.   The manufacturing method of an adhesive sheet | seat including the process of irradiating a laser beam and cut | disconnecting the adhesive sheet in any one of Claim 1 to 9 so that a said 1st base material may not be cut | disconnected completely.   The manufacturing method of the adhesive sheet of Claim 10 which irradiates a laser beam from the opposite side to a said 1st base material. The laser is a CO ₂ laser, a manufacturing method of the pressure-sensitive adhesive sheet according to claim 10 or 11.   The adhesive sheet obtained by the manufacturing method in any one of Claim 10 to 12.

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