JP2014189778A - Double-sided tacky sheet and coiled body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a double-sided tacky sheet capable, when coiled and stored in the form of a roll, of preventing the generation of multiple fine valleys and peaks on the tackifier layer surface; and a coiled body obtained by coiling the double-sided tacky sheet.SOLUTION: The double-sided tacky sheet of the present invention includes a tackifier layer, a first release film, and a second release film, the peel force of the second release film from the tackifier layer is less than the peel force of the first release film from the tackifier layer, the tackifier layer is formed by using a tackifier including an active energy ray-curable resin, the gel content of the tackifier layer immediately after the formation thereof is at least 70%, in a case where the gel content of the tackifier layer immediately after the formation thereof is defined as X [%] and where the gel content of the tackifier layer seven days after the formation of the tackifier layer is defined as Y [%], the relation of X/Y≥0.9 is satisfied, and the ratio occupied, on first and second surfaces of the tackifier layer, by valleys and peaks beyond a range of ±200 nm from the reference plane is 20% or less.

Description

  The present invention relates to a double-sided pressure-sensitive adhesive sheet and a wound body.

  An optical functional film such as a polarizing plate is fixed using a double-sided pressure-sensitive adhesive sheet composed of a member such as a liquid crystal cell and an adhesive. Moreover, such a double-sided adhesive sheet forms a coating film by apply | coating an adhesive on a 1st peeling film, for example, Then, a 2nd peeling film is bonded on the formed coating film, and an ultraviolet-ray Manufactured by curing by irradiation or the like to form an adhesive layer. And the double-sided adhesive sheet manufactured in this way is generally wound up (rolled) and stored and transported in a roll shape.

  In recent years, for the purpose of improving productivity, the winding length of such a double-sided pressure-sensitive adhesive sheet wound up in a roll shape has increased, and in order to increase the length, it is wound with an excessive tension. As a result, there was a problem that a plurality of minute irregularities (skin skin) occurred on the surface of the pressure-sensitive adhesive layer, which was not a problem in the past.

  Therefore, attempts have been made to prevent such skin by setting the surface roughness Ra of the release-treated surface of the release film to 100 nm or less (see, for example, Patent Document 1).

  However, along with the recent increase in roll winding length, the conventional double-sided PSA sheet has not been able to sufficiently prevent the generation of crushed skin at the roll core.

  In addition, conventionally, the autoclaving treatment was performed after the polarizing plate with the pressure-sensitive adhesive was bonded to the liquid crystal cell, but in recent years, the autoclave treatment may not be performed in order to simplify the process. For this reason, there is a problem that, when the skin is generated in the pressure-sensitive adhesive layer, there is a high possibility that fine bubbles are mixed, leading to a decrease in yield. In addition, if the adhesive layer has crushed skin, poor appearance occurs when incorporated in a display, resulting in a decrease in yield.

JP 2010-185038 A

  An object of the present invention is to provide a double-sided pressure-sensitive adhesive sheet capable of preventing the occurrence of a plurality of minute irregularities (skin skin) on the surface of the pressure-sensitive adhesive layer when wound and stored in a roll shape, and the double-sided pressure-sensitive adhesive sheet It is to provide a wound body that has been wound.

Such an object is achieved by the present inventions (1) to (5) below.
(1) an adhesive layer comprising a first surface and a second surface;
A first release film adhered to the first surface of the pressure-sensitive adhesive layer;
A second release film adhered to the second surface of the pressure-sensitive adhesive layer,
The peeling force from the pressure-sensitive adhesive layer of the second release film is smaller than the peeling force from the pressure-sensitive adhesive layer of the first release film,
The pressure-sensitive adhesive layer is formed using a pressure-sensitive adhesive containing an active energy ray-curable resin,
The gel fraction immediately after formation of the pressure-sensitive adhesive layer is 70% or more,
When the gel fraction immediately after formation of the pressure-sensitive adhesive layer is X [%] and the gel fraction of the pressure-sensitive adhesive layer 7 days after the formation of the pressure-sensitive adhesive layer is Y [%], X / Y ≧ 0.9 relationship is satisfied,
The ratio of the unevenness outside the range of ± 0.2 μm from the reference surface in the first surface and the second surface of the pressure-sensitive adhesive layer is 20% or less.

  (2) The double-sided pressure-sensitive adhesive sheet according to (1), wherein a storage elastic modulus of the pressure-sensitive adhesive layer at 23 ° C. after 7 days from the formation of the pressure-sensitive adhesive layer is 0.15 MPa or more.

  (3) The arithmetic average roughness Ra of the surface opposite to the surface in contact with the pressure-sensitive adhesive layer of the first release film and the second release film is 50 nm or less, and the maximum protrusion height Rp The double-sided pressure-sensitive adhesive sheet according to the above (1) or (2), wherein the thickness is 1000 nm or less.

  (4) The peel force from the pressure-sensitive adhesive layer of the first release film is X [mN / 25 mm], and the peel force from the pressure-sensitive adhesive layer of the second release film is Y [mN / 25 mm]. The double-sided pressure-sensitive adhesive sheet according to any one of (1) to (3), wherein the relationship of XY ≧ 5 is satisfied.

  (5) A wound body obtained by winding the double-sided pressure-sensitive adhesive sheet according to any one of (1) to (4).

  According to the present invention, for example, it is used to stick an optical functional film such as a polarizing plate, and when wound and wound in a roll shape (stored), a plurality of fine particles are formed on the surface of the pressure-sensitive adhesive layer. It is possible to provide a double-sided pressure-sensitive adhesive sheet that can prevent unevenness from occurring.

It is a cross-sectional view of the double-sided pressure-sensitive adhesive sheet of the present invention.

Hereinafter, the present invention will be described in detail based on preferred embodiments.
《Double-sided adhesive sheet》
The double-sided pressure-sensitive adhesive sheet of the present invention is used, for example, for bonding an optical functional film such as a polarizing plate and a member such as a liquid crystal cell.

FIG. 1 is a cross-sectional view of the double-sided pressure-sensitive adhesive sheet of the present invention.
As shown in FIG. 1, the double-sided pressure-sensitive adhesive sheet 1 includes a pressure-sensitive adhesive layer 10 having a first surface 101 and a second surface 102, and a first surface provided on the first surface 101 of the pressure-sensitive adhesive layer 10. The release film 11 and the second release film 12 provided on the second surface 102 of the pressure-sensitive adhesive layer 10 are included. The pressure-sensitive adhesive layer 10 does not have anything that becomes a support after the first release film 11 and the second release film 12 have been removed.

  As described above, the double-sided pressure-sensitive adhesive sheet 1 of the present invention is the double-sided pressure-sensitive adhesive sheet 1 having the pressure-sensitive adhesive layer 10, the first release film 11, and the second release film 12, and has the following characteristics. have. That is, in the double-sided pressure-sensitive adhesive sheet 1 of the present invention, (1) the peeling force from the pressure-sensitive adhesive layer 10 of the second release film 12 is smaller than the peeling force from the pressure-sensitive adhesive layer 10 of the first release film 11. (2) The pressure-sensitive adhesive layer 10 is formed using a pressure-sensitive adhesive composition containing an active energy ray-curable resin, and (3) the gel fraction immediately after the formation of the pressure-sensitive adhesive layer 10 is (4) The gel fraction immediately after formation of the pressure-sensitive adhesive layer 10 is X [%], and the gel fraction of the pressure-sensitive adhesive layer 10 seven days after the formation of the pressure-sensitive adhesive layer 10 is Y When [%] is satisfied, the relationship X / Y ≧ 0.9 is satisfied, and (5) irregularities outside the range of ± 0.2 μm from the reference surface on the first surface and the second surface of the pressure-sensitive adhesive layer 10 The ratio occupied by is characterized by being 20% or less.

  By having such a feature, when the double-sided pressure-sensitive adhesive sheet 1 is wound up in a roll shape and stored and transported, it is possible to prevent generation of minute irregularities (skin skin) on the surface of the pressure-sensitive adhesive layer 10. it can. This is considered to be due to the following reasons.

  That is, the gel fraction immediately after formation of the pressure-sensitive adhesive layer 10 can be made relatively high by forming the pressure-sensitive adhesive layer 10 using a pressure-sensitive adhesive composition containing an active energy ray-curable resin. And generation | occurrence | production of the fine unevenness | corrugation (skin skin) in the time of winding can be suppressed by making the gel fraction immediately after formation of the adhesive layer 10 into a comparatively high thing. Moreover, it can suppress that a micro unevenness | corrugation (swell skin) generate | occur | produces with time by making the change of the gel fraction with progress of time small.

  In addition, the gel fraction immediately after the formation of the pressure-sensitive adhesive layer 10 is made relatively high, and the change in the gel fraction over time is made small so that the first surface and the first surface of the pressure-sensitive adhesive layer 10 The ratio of the unevenness outside the range of ± 0.2 μm from the reference surface in the surface of 2 can be reduced, and the generation of crushed skin can be prevented.

  Moreover, when peeling the 2nd peeling film from the adhesive layer 10 by making the peeling force from the adhesive layer 10 of a 2nd peeling film smaller than the peeling force from the adhesive layer of a 1st peeling film. In addition, a part of the pressure-sensitive adhesive layer 10 sticks to the second release film, and the phenomenon that the pressure-sensitive adhesive layer having a smooth and good appearance does not remain on the first release film, that is, so-called tearing occurs. Can be prevented.

  In addition, in this specification, the peeling force from an adhesive layer means the peeling force measured as follows.

  The peel force was measured in accordance with JIS-Z0237. The double-sided pressure-sensitive adhesive sheet was cut into a width of 25 mm and a length of 200 mm, and the release film was 300 mm / min with the pressure-sensitive adhesive layer fixed using a tensile tester. It shall be performed by pulling in the 180 ° direction at a speed.

  Further, in this specification, the storage elastic modulus of the pressure-sensitive adhesive layer refers to storage elasticity measured by laminating a pressure-sensitive adhesive, preparing a cylindrical test piece having a thickness of 8 mmφ × 3 mm, and measuring the following conditions by the torsional shear method. It means rate.

  Measuring device: Dynamic viscoelasticity measuring device “DYNAMIC ANALYZER RDAII” manufactured by Rheometric, frequency: 1 Hz, temperature: 23 ° C.

Hereinafter, each layer which comprises the double-sided adhesive sheet 1 which concerns on this embodiment is demonstrated in detail.
<Adhesive layer 10>
The pressure-sensitive adhesive layer 10 has a first surface 101 and a second surface 102.

  The pressure-sensitive adhesive layer 10 has a gel fraction immediately after its formation of 70% or more, the gel fraction immediately after the formation of the pressure-sensitive adhesive layer 10 is X [%], and the pressure-sensitive adhesive layer 7 days after the pressure-sensitive adhesive layer 10 is formed. When the gel fraction of the agent layer 10 is Y [%], the relationship of X / Y ≧ 0.9 is satisfied, and the first surface 101 and the second surface 102 are within a range of ± 0.2 μm from the reference surface. The proportion of outer irregularities is 20% or less. Thereby, when it affixes on a to-be-adhered body, it can prevent that an appearance defect generate | occur | produces.

  In addition, although the gel fraction immediately after formation of the adhesive layer 10 is 70% or more, it is more preferable that it is 75% or more. Thereby, when it affixes on a to-be-adhered body, it can prevent more effectively that an external appearance defect generate | occur | produces.

  In the pressure-sensitive adhesive layer 10, the proportion of the unevenness outside the range of ± 0.2 μm from the reference surface in the first surface 101 and the second surface 102 is 20% or less, but is 10% or less. Is more preferable. Thereby, when it affixes on a to-be-adhered body, it can prevent more reliably that appearance defect generate | occur | produces.

  The pressure-sensitive adhesive layer 10 preferably has a storage elastic modulus at 23 ° C. after 7 days from the formation of the pressure-sensitive adhesive layer 10 of 0.15 MPa or more, more preferably 0.3 MPa or more. . Thereby, when the double-sided pressure-sensitive adhesive sheet 1 is wound, it is possible to more effectively prevent the skin from being generated on the surface of the pressure-sensitive adhesive layer 10. Moreover, the change of the dimension by the heat etc. of optical functional films, such as a polarizing plate, can be suppressed.

  Although it does not specifically limit as an adhesive which comprises the adhesive layer 10, An active energy ray is irradiated to the adhesive composition containing (A) acrylic copolymer and (B) active energy ray hardening-type compound. It is preferable to use an adhesive. Thereby, the storage elastic modulus of the adhesive layer 10 can be made relatively high, and the durability (heat resistance, low temperature resistance, moisture resistance, etc.) of the adhesive layer 10 can be made higher. .

  Examples of the acrylic copolymer (A) include (meth) acrylic acid ester copolymers. In addition, in this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

  As the (meth) acrylic acid ester copolymer, it is preferable to use a copolymer having a crosslinking point that can be crosslinked by various crosslinking methods. The (meth) acrylic acid ester-based copolymer having such a crosslinking point is not particularly limited, and among (meth) acrylic acid ester-based copolymers conventionally used as a resin component of an adhesive, Any one can be selected and used.

  As the (meth) acrylic acid ester-based copolymer having such a crosslinking point, a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the ester group and a crosslinkable functional group in the molecule. It is preferable to use a copolymer of the monomer having and other monomers used as desired. Here, examples of (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group of the ester moiety include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, ( (Meth) butyl acrylate, (meth) acrylic acid pentyl, (meth) acrylic acid hexyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid isooctyl, (meth) acrylic acid decyl, Examples include dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, one kind or two or more kinds may be used in combination.

  On the other hand, the monomer having a crosslinkable functional group in the molecule preferably contains at least one of a hydroxyl group, a carboxyl group, and an amino group as a functional group. Specific examples include 2-hydroxyethyl (meth) acrylate. 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate Such as (meth) acrylic acid hydroxyalkyl ester; (meth) acrylic acid monomethylaminoethyl, (meth) acrylic acid monoethylaminoethyl, (meth) acrylic acid monomethylaminopropyl, (meth) acrylic acid monoethylaminopropyl, etc. (Meth) acrylic acid monoalkylaminoalkyl; acrylic acid, methacrylic acid, crotonic acid, Ynoic acid, itaconic acid, ethylenically unsaturated carboxylic acids such as citraconic acid. These monomers may be used independently and may be used in combination of 2 or more type.

  In the pressure-sensitive adhesive composition, the (meth) acrylic acid ester copolymer (A) is not particularly limited as to its copolymerization form, and may be any of random, block, and graft copolymers.

  The (meth) acrylic acid ester copolymer (A) preferably has a mass average molecular weight of 500,000 or more, more preferably 600,000 to 2,000,000. It is more preferable to use 10,000 to 1,800,000. Thereby, the adhesiveness and adhesion durability with the adherend are sufficient, and the occurrence of floating and peeling can be more effectively prevented. The mass average molecular weight is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

  Furthermore, in this (meth) acrylic acid ester copolymer, the content of the monomer unit having a crosslinkable functional group in the molecule is preferably in the range of 0.01 to 10% by mass. When the content is 0.01% by mass or more, crosslinking is sufficient due to a reaction with a crosslinking agent described later, and durability is improved. On the other hand, when the content is 10% by mass or less, the degree of cross-linking becomes too high, and the suitability for bonding to a liquid crystal glass cell or a retardation plate is not deteriorated. Considering durability and suitability for bonding to a liquid crystal glass cell or a retardation plate, the more preferable content of the monomer unit having this crosslinkable functional group is 0.05 to 7.0% by mass, The range of 0.2-6.0 mass% is preferable.

  In addition, as a (meth) acrylic acid ester type copolymer (A), 1 type may be used and it may be used in combination of 2 or more type.

  In the pressure-sensitive adhesive composition, a polyfunctional (meth) acrylate monomer having a molecular weight of less than 1000 can be used as the active energy ray-curable compound (B).

  Examples of the polyfunctional (meth) acrylate monomer having a molecular weight of less than 1000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, Polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate , Bifunctional types such as ethylene oxide-modified di (meth) acrylate phosphate, di (acryloxyethyl) isocyanurate, and allylated cyclohexyl di (meth) acrylate; trimethylolpropane tri ( Acrylate), dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) ) Trifunctional type such as isocyanurate; tetrafunctional type such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate; dipentaerythritol Hexafunctional type such as hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, etc. are mentioned, and among these, one type or two or more types are included. It may be used in conjunction seen. Of the polyfunctional (meth) acrylate monomers described above, those containing a skeleton structure having a cyclic structure are preferably used. The cyclic structure may be a carbocyclic structure or a heterocyclic structure, and may be a monocyclic structure or a polycyclic structure. Examples of such polyfunctional (meth) acrylate monomers include those having an isocyanurate structure such as di (acryloxyethyl) isocyanurate, tris (acryloxyethyl) isocyanurate, dimethylol dicyclopentane diacrylate, Ethylene oxide-modified hexahydrophthalic acid diacrylate, tricyclodecane dimethanol acrylate, neopentyl glycol-modified trimethylolpropane diacrylate, adamantane diacrylate, and the like can be suitably used.

  Moreover, an active energy ray-curable acrylate oligomer can be used as the active energy ray-curable compound (B). The acrylate oligomer preferably has a mass average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

  Here, the polyester acrylate oligomer is obtained by, for example, esterifying the hydroxyl group of a polyester oligomer having hydroxyl groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid. It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to a carboxylic acid with (meth) acrylic acid. The epoxy acrylate oligomer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it. A carboxyl-modified epoxy acrylate oligomer obtained by partially modifying this epoxy acrylate oligomer with a dibasic carboxylic acid anhydride can also be used. The urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by the reaction of polyether polyol or polyester polyol and polyisocyanate with (meth) acrylic acid. It can be obtained by esterifying the hydroxyl group of ether polyol with (meth) acrylic acid.

  The mass average molecular weight of the acrylate oligomer is a value in terms of standard polymethyl methacrylate measured by GPC method, preferably 50,000 or less, more preferably 500 to 50,000, still more preferably 3,000 to 40,000. It is selected in the range.

  These acrylate oligomers may be used alone or in combination of two or more.

  Further, as the active energy ray-curable compound (B), an adduct acrylate polymer in which a group having a (meth) acryloyl group is introduced into the side chain can also be used. Such an adduct acrylate polymer is a copolymer of the (meth) acrylic acid ester described in the (meth) acrylic acid ester copolymer (A) and a monomer having a crosslinkable functional group in the molecule. And a compound having a (meth) acryloyl group and a group capable of reacting with the crosslinkable functional group is allowed to react with a part of the crosslinkable functional group of the copolymer. The mass average molecular weight of the adduct acrylate polymer is usually 500,000 to 2,000,000 in terms of polystyrene.

  In addition, as the active energy ray-curable compound (B), one type may be appropriately selected from the above-mentioned polyfunctional acrylate monomers, acrylate oligomers, and adduct acrylate polymers, and two or more types may be used in combination. May be.

The content ratio of the (meth) acrylic acid ester copolymer (A) and the active energy ray-curable compound (B) in the pressure-sensitive adhesive composition is a mass ratio from the aspect of the performance of the pressure-sensitive adhesive obtained. The ratio is preferably 100: 1 to 100: 100, more preferably 100: 5 to 100: 50, and still more preferably 100: 10 to 100: 40.
Further, the pressure-sensitive adhesive composition may contain a photopolymerization initiator as necessary.

  Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylamino Benzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2,4 , 6-trimethylbenzoyl-diphenyl-phosphine oxide and the like, and among these, one kind or two or more kinds may be used in combination.

Moreover, it is preferable that the compounding quantity of the photoinitiator in an adhesive composition is 0.2-20 mass parts with respect to 100 mass parts of active energy ray hardening-type compounds (B).
Moreover, the pressure-sensitive adhesive composition may contain a crosslinking agent as required.

  There is no restriction | limiting in particular as a crosslinking agent, Arbitrary things can be suitably selected and used from what was conventionally used as a crosslinking agent in an acrylic adhesive. Examples of such a cross-linking agent include polyisocyanate compounds, epoxy resins, melamine resins, urea resins, dialdehydes, methylol polymers, aziridine compounds, metal chelate compounds, metal alkoxides, metal salts, and the like. Of these, one or two or more can be used in combination. Among these, it is preferable to use a polyisocyanate compound as a crosslinking agent.

  Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like. Examples thereof include biurets, isocyanurates, and adducts that are a reaction product with a low-molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil.

  The addition amount of the crosslinking agent is preferably 0.01 to 20 parts by mass, and preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the (meth) acrylic ester copolymer (A). More preferred.

  Moreover, the silane coupling agent may be contained in the adhesive composition as needed. By including this silane coupling agent, when an optical functional film such as a polarizing plate is bonded to, for example, a liquid crystal glass cell, the adhesion between the pressure-sensitive adhesive and the glass cell becomes better. This silane coupling agent is an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the pressure-sensitive adhesive component, and having light transparency, for example, substantially transparent Is preferred.

  The addition amount of the silane coupling agent is preferably 0.001 to 10 parts by mass, and more preferably 0.005 to 5 parts by mass with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition.

  Specific examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltrimethoxysilane and other silicon compounds having an epoxy structure, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2- Amino group-containing silicon compounds such as aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.

  In the pressure-sensitive adhesive composition, various additives usually used in acrylic pressure-sensitive adhesives as desired, for example, a tackifier, an antistatic agent, an antioxidant, and an ultraviolet absorber, as long as the object of the present invention is not impaired. Agents, light stabilizers, softeners, fillers and the like can be added.

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 10 is formed by irradiating an active energy ray to a pressure-sensitive adhesive composition composed of the components described above.

  Examples of active energy rays include ultraviolet rays and electron beams. The ultraviolet light can be obtained from a high-pressure mercury lamp, an electrodeless lamp, a xenon lamp, or the like. The electron beam can be obtained by an electron beam accelerator or the like.

  Among the active energy rays, it is particularly preferable to use ultraviolet rays. In addition, when using an electron beam, an adhesive can be formed, without adding a photoinitiator.

The irradiation amount of the active energy ray for the pressure-sensitive adhesive composition is appropriately selected so as to obtain a pressure-sensitive adhesive having a gel fraction immediately after formation as described above. In the case of ultraviolet rays, the illuminance is 50 to 1000 mW / cm. ² , In the case of an electron beam, the range of 10 to 1000 krad is preferable in the case of an amount of light of 50 to 1000 mJ / cm ² .

  The average thickness of the pressure-sensitive adhesive layer 10 is preferably 3 to 30 μm, and more preferably 4 to 28 μm. Thereby, it can be set as the thinness suitable for using for a thin display.

[First release film]
The first release film 11 is attached to the first surface 101 of the pressure-sensitive adhesive layer 10.
The first release film 11 has a function of protecting the pressure-sensitive adhesive layer 10.

  As shown in FIG. 1, the first release film 11 is a laminate in which a first release agent layer 111 and a first base film 112 are sequentially laminated from the side in contact with the pressure-sensitive adhesive layer 10. It is configured.

  The first base film 112 has a function of imparting physical strength such as rigidity and flexibility to the first release film 11.

  Examples of the material constituting the first base film 112 include various synthetic resins. For example, it is preferable to use a polyester resin such as polybutylene terephthalate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, and polyethylene terephthalate. It is more preferable to use a resin. Note that the first base film 112 may be a single-layer film or a multilayer film having two or more layers made of the same or different materials. Such a multilayer film may be obtained by laminating films formed in advance through an adhesive layer as necessary, or by coating a resin film forming composition on a film formed in advance. But you can. The resin layer forming composition for forming the resin layer is mainly composed of an epoxy compound, an acrylate compound, a urethane acrylate compound, a polyester compound, etc., and if necessary, a crosslinking agent, a catalyst, and photopolymerization start. And those containing an agent, an ultraviolet absorber and the like. These composition for resin layer formation may have sclerosis | hardenability, for example, any, such as thermosetting, photocurability, or electron beam sclerosis | hardenability, may be sufficient. In this way, the arithmetic average roughness Ra of the outer surface of the first base film 112 is obtained by using the multilayer film in which the resin layer forming composition is coated on the film formed in advance and the resin layer is formed. In addition, the maximum protrusion height Rp can be adjusted.

  Note that the first base film 112 may contain a filler. Examples of the filler include silica, titanium oxide, calcium carbonate, kaolin, and aluminum oxide.

  Although the thickness of the 1st base film 112 does not have a restriction | limiting in particular, It is preferable that it is 10-300 micrometers, and it is more preferable that it is 15-200 micrometers.

  Moreover, it is preferable that arithmetic mean roughness Ra of the surface on the opposite side to the surface which contact | connects the adhesive layer 10 of the 1st peeling film 11 is 50 nm or less, and it is more preferable that it is 5-25 nm. Thereby, when the double-sided pressure-sensitive adhesive sheet 1 is wound up in a roll shape, it is possible to more effectively prevent the skin from being generated on the first surface 101 and the second surface 102 of the pressure-sensitive adhesive layer 10. .

  Moreover, it is preferable that the maximum protrusion height Rp of the surface on the opposite side to the surface which contact | connects the adhesive layer 10 of the 1st peeling film 11 is 1000 nm or less, and it is more preferable that it is 50-250 nm. Thereby, when the double-sided pressure-sensitive adhesive sheet 1 is wound, it is possible to more effectively prevent the skin from being generated on the first surface 101 and the second surface 102 of the pressure-sensitive adhesive layer 10.

  The first release agent layer 111 has a function of imparting peelability to the first release film 11.

  The first release agent layer 111 is formed by applying a first release agent layer-forming composition containing the first release agent to the surface of the first base film 112 and drying it.

  The first release agent is not particularly limited, and examples thereof include alkyd compounds, acrylic compounds, silicone compounds, long chain alkyl group-containing compounds, and fluorine compounds. Among these, as the first release agent, it is preferable to use an alkyd compound, an acrylic compound, a silicone compound, or a long-chain alkyl group-containing compound.

  As the alkyd compound, an alkyd compound having a crosslinked structure is generally used. Formation of the alkyd compound layer having a crosslinked structure can be performed, for example, by a method in which a layer made of a thermosetting composition containing an alkyd compound, a crosslinking agent, and optionally a curing catalyst is heated and cured. The alkyd compound may be a modified product such as a long-chain alkyl-modified alkyd compound or a silicone-modified alkyd compound.

  As the acrylic compound, an acrylic compound having a crosslinked structure is generally used. The acrylic compound may be a modified product such as a long-chain alkyl-modified acrylic compound or a silicone-modified acrylic compound.

  Examples of the silicone compound include a silicone compound having dimethylpolysiloxane as a basic skeleton. Examples of the silicone compound include an addition reaction type, a condensation reaction type, an ultraviolet curable type, and an electron beam curable type. The addition reaction type silicone compound has high reactivity and excellent productivity, and has advantages such as little change in peel strength after production and no cure shrinkage compared to the condensation reaction type.

  As a specific example of the above addition reaction type silicone compound, two or more alkenyl groups having 2 to 10 carbon atoms such as vinyl group, allyl group, propenyl group, hexenyl group and the like are provided at the terminal and / or side chain of the molecule. Organopolysiloxane is mentioned. When such an addition reaction type silicone compound is used, it is preferable to use a crosslinking agent and a catalyst in combination.

  Examples of the crosslinking agent include, for example, organopolysiloxane having hydrogen atoms bonded to at least two silicon atoms in one molecule, specifically, a dimethylhydrogensiloxy group end-capped dimethylsiloxane-methylhydrogensiloxane copolymer. , Trimethylsiloxy group end-capped dimethylsiloxane-methylhydrogensiloxane copolymer, trimethylsiloxy group end-capped methylhydrogenpolysiloxane, poly (hydrogensilsesquioxane), and the like.

  In addition, as the catalyst, fine platinum, fine platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, white metal compounds such as palladium and rhodium Etc. By using such a catalyst, the curing reaction of the composition for forming a release agent layer can be advanced more efficiently.

  Examples of the long-chain alkyl group-containing compound include a polyvinyl carbamate obtained by reacting a polyvinyl alcohol polymer with a long-chain alkyl isocyanate having 8 to 30 carbon atoms, or a long-chain alkyl having 8 to 30 carbon atoms with polyethyleneimine. An alkylurea derivative obtained by reacting isocyanate is used.

  Examples of the fluorine compound include a fluorine silicone compound and a fluorine boron compound.

  You may mix | blend an additive with a 1st peeling agent composition suitably. Examples of the additive include a catalyst, a dye, and a dispersant.

  In the first release agent layer 111, the material of the first release agent layer forming composition described above so that the release force of the first release film 11 is greater than the release force of the second release film 12. Is appropriately selected.

  When using a resin comprising a silicone compound as the first release agent, it is preferable to add an appropriate amount of MQ resin as a heavy release control agent.

  The first release agent composition may appropriately contain a dispersion medium or a solvent in order to bring the viscosity at the time of application to an appropriate range.

  Preferred examples of the dispersion medium or solvent include aromatic hydrocarbons such as toluene, fatty acid esters such as ethyl acetate, ketones such as methyl ethyl ketone, and organic solvents such as aliphatic hydrocarbons such as hexane and heptane.

  The content of the first release agent in the first release agent composition is not particularly limited, but is preferably 0.3 to 10% by mass.

  As the coating method, for example, gravure coating method, bar coating method, spray coating method, spin coating method, air knife coating method, roll coating method, blade coating method, gate roll coating method, die coating method, etc. can be used. A gravure coating method and a bar coating method are preferable, and a bar coating method is particularly preferable.

  The drying temperature is not particularly limited, but is preferably 100 to 150 ° C., and the drying time is preferably 10 seconds to 1 minute.

  The thickness of the first release agent layer is preferably from 0.01 to 5 μm, particularly preferably from 0.03 to 3 μm.

  The first release film 11 has an arithmetic average roughness Ra of a surface in contact with the pressure-sensitive adhesive layer 10 (an outer surface of the first release agent layer 111) of 50 nm or less, and a maximum protrusion height Rp of 800 nm or less. In addition, the proportion of the unevenness outside the range of ± 0.2 μm from the reference surface on the outer surface of the first release agent layer 111 is preferably 20% or less. Thereby, when the adhesive layer 10 is formed on the 1st peeling film 11, the surface shape of the 1st surface 101 of the adhesive layer 10 can be made favorable.

[Second release film]
The second release film 12 is attached to the second surface 102 of the pressure-sensitive adhesive layer 10.
The second release film 12 has a function of protecting the pressure-sensitive adhesive layer 10.

  As shown in FIG. 1, the second release film 12 is a laminate in which a second release agent layer 121 and a second base film 122 are sequentially laminated from the side in contact with the pressure-sensitive adhesive layer 10. It is configured.

  As the 2nd base film 122, it can select suitably from the material which comprises the 1st base film 112 demonstrated in the term of the 1st peeling film 11 mentioned above, and can use it.

  Moreover, it is preferable that arithmetic mean roughness Ra of the surface on the opposite side to the surface which contact | connects the adhesive layer 10 of the 2nd peeling film 12 is 50 nm or less, and it is more preferable that it is 5-25 nm. Thereby, when the double-sided pressure-sensitive adhesive sheet 1 is wound, it is possible to more effectively prevent the skin from being generated on the first surface 101 and the second surface 102 of the pressure-sensitive adhesive layer 10.

  Moreover, it is preferable that the maximum protrusion height Rp of the surface on the opposite side to the surface which contact | connects the adhesive layer 10 of the 2nd peeling film 12 is 1000 nm or less, and it is more preferable that it is 50-250 nm. Thereby, when the double-sided pressure-sensitive adhesive sheet 1 is wound, it is possible to more effectively prevent the skin from being generated on the first surface 101 and the second surface 102 of the pressure-sensitive adhesive layer 10.

  The second release agent layer 121 is formed by applying a second release agent layer-forming composition containing the second release agent to the surface of the second base film 122 and drying it.

  As a 2nd release agent, it can select suitably from the material which comprises the 1st release agent demonstrated by the term of the 1st release film mentioned above, and can use it.

  In the second release agent layer 121, the material of the second release agent layer forming composition described above so that the release force of the second release film 12 is smaller than the release force of the first release film 11. Is appropriately selected.

  The second release agent layer 121 may be a single layer or a plurality of layers of two or more layers, but a single layer is preferable in order to simplify the operation.

  The thickness of the second release agent layer 121 is preferably 0.01 to 5 μm, and more preferably 0.03 to 3 μm.

  In addition, the second release film 12 has an arithmetic average roughness Ra of a surface in contact with the pressure-sensitive adhesive layer 10 (an outer surface of the second release agent layer 121) of 50 nm or less, and a maximum protrusion height Rp of 800 nm or less. In addition, it is preferable that the ratio of the unevenness outside the range of ± 0.2 μm from the reference surface on the outer surface of the second release agent layer 121 is 20% or less. Thereby, when the 2nd peeling film 12 was bonded on the 2nd surface 102 of the adhesive layer 10, and the double-sided adhesive sheet 1 was produced, the surface shape of the 2nd surface 102 of the adhesive layer 10 was changed. Can be good.

  When the peeling force from the pressure-sensitive adhesive layer 10 of the first release film 11 is X [mN / 25 mm] and the peeling force from the pressure-sensitive adhesive layer 10 of the second release film 12 is Y [mN / 25 mm], X It is preferable to satisfy the relationship of −Y ≧ 5, and it is more preferable to satisfy the relationship of 60 ≧ XY ≧ 10. Thereby, when peeling the 2nd peeling film 12 from the adhesive layer 10, a part of adhesive layer 10 will adhere to the 2nd peeling film 12, and a smooth and good external appearance is on the 1st peeling film. It is possible to more effectively prevent a phenomenon in which the state of the pressure-sensitive adhesive layer does not remain, that is, so-called crying separation.

《Circle>
The wound body of the present invention is obtained by winding the double-sided pressure-sensitive adhesive sheet of the present invention as described above. Therefore, the generation of a plurality of minute irregularities (skin skin) on the pressure-sensitive adhesive layer surface is prevented.

  As mentioned above, although this invention was demonstrated in detail based on preferred embodiment, this invention is not limited to this.

Next, specific examples of the release film of the present invention will be described.
[1] Preparation of double-sided PSA sheet (Example 1)
1. Preparation of First Release Film A polyethylene terephthalate (PET) film (thickness 38 μm, arithmetic average roughness Ra: 15 nm, maximum protrusion height Rp: 159 nm) having the same roughness on the front and back sides was prepared as the first base film. .

  Next, on one surface of the first base film, the first release agent layer-forming composition A having the following composition was applied with a bar coater so that the thickness after drying was 0.1 μm. It dried at 120 degreeC for 1 minute, and provided the 1st releasing agent layer. This obtained the 1st peeling film. Arithmetic mean roughness Ra and maximum of the surface of the obtained first release film on the first release agent layer side and the surface on the first base film side (surface opposite to the surface in contact with the adhesive layer) Table 1 shows the projection height Rp and the ratio of the unevenness outside the range of ± 0.2 μm from the reference surface on the first release agent layer side surface of the first release film.

(Preparation of first release agent layer-forming composition A)
Silicone resin solution containing organopolysiloxane with vinyl group and organopolysiloxane with hydrosilyl group (manufactured by Toray Dow Corning Co., Ltd., trade name “BY24-561”, solid content 30% by mass) in terms of solid content 30 parts by mass and 15 parts by mass of solid resin in terms of solid content of MQ resin (made by Toray Dow Corning Co., Ltd., trade name “SD7292”, solid content 71% by mass) having a vinyl group, and solid content concentration in toluene solvent Was diluted and mixed so as to be 1.0% by mass. To this solution, 2 parts by mass of a platinum-based catalyst (trade name “SRX-212”, manufactured by Toray Dow Corning Co., Ltd., solid content: 100% by mass) was added to prepare a first release agent layer forming composition A.

2. Production of Second Release Film As a second base film, a polyethylene terephthalate (PET) film (thickness 38 μm, arithmetic average roughness Ra: 30 nm, maximum protrusion height Rp: 535 nm) having the same front and back surfaces was prepared. .

  Next, a second release agent layer-forming composition B having the following composition was applied to one surface of the second base film with a bar coater so that the thickness after drying was 0.1 μm. A second release film was prepared by drying at 120 ° C. for 1 minute and providing a second release agent layer. Arithmetic mean roughness Ra and maximum of the surface on the second release agent layer side of the obtained second release film and the surface on the second substrate film side (surface opposite to the surface in contact with the adhesive layer) Table 1 shows the protrusion height Rp and the ratio of the unevenness outside the range of ± 0.2 μm from the reference surface on the surface of the second release film on the second release agent layer side.

(Preparation of second release agent layer-forming composition B)
100 parts by mass of a silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name “KS847H”, solid content concentration 30% by mass) and 1 part by mass of a platinum-based catalyst (manufactured by Shin-Etsu Chemical Co., Ltd .: trade name “CAT-PL50T”, solid content) 2% by mass) was diluted with toluene to prepare a second release agent layer-forming composition B having a solid content concentration of 1% by mass.

3. Preparation of pressure-sensitive adhesive composition In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device and a nitrogen introduction tube, 95.0 parts by mass of n-butyl acrylate, 5.0 parts by mass of 2-hydroxyethyl acrylate 200 parts by mass of ethyl acetate and 0.08 part by mass of 2,2′-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 60 ° C., reacted for 16 hours, and then cooled to room temperature. Here, a part of the obtained solution was subjected to GPC measurement, and production of a polymer (A) having a mass average molecular weight of 1.6 million was confirmed. 100 parts by mass (solid content) of the above polymer (A) 20 parts by mass of tris (acryloxyethyl) isocyanurate (trade name “Aronix M-315” manufactured by Toagosei Co., Ltd.), photopolymerization initiator (Ciba Specialty) Chemicals, product name "Irgacure 500" 2.0 parts by mass, polyisocyanate crosslinking agent (Japan Polyurethanes, product name "Coronate L") 4 parts by mass, and silane coupling agent (Shin-Etsu Chemical Co., Ltd.) “KBM-403”) 0.1 mass part was added and mixed, and toluene was further added as a solvent to adjust the solid content to 15 mass% to prepare an adhesive composition A.

4). Preparation of double-sided pressure-sensitive adhesive sheet The pressure-sensitive adhesive composition A was applied onto the release agent layer of the first release film so that the thickness after drying was 20 μm, and dried at 90 ° C. for 1 minute to give a pressure-sensitive adhesive layer. Formed. Next, on the formed pressure-sensitive adhesive layer, a silicone rubber roll (rubber hardness: 80) and a metal roll whose laminating pressure is adjusted to 0.5 MPa so that the release agent layer of the second release film is in contact with the pressure-sensitive adhesive layer, And bonded at a speed of 50 m / min under normal temperature conditions. Next, ultraviolet light (UV) was irradiated from under the first release film under the following conditions to produce a double-sided PSA sheet.

<UV irradiation conditions>
・ Uses an electrodeless lamp H bulb manufactured by Fusion.
・ Illuminance 600mW / cm2, light quantity 150mJ / cm2
As the UV illuminance / light meter, “UVPF-36” manufactured by Eye Graphics was used.

(Example 2)
Adhesive as in Example 1 except that 20 parts by mass of tris (acryloxyethyl) isocyanurate (trade name “Aronix M-315”, manufactured by Toagosei Co., Ltd.) of the adhesive composition A was changed to 15 parts by mass. Composition B was prepared to produce a double-sided PSA sheet.

(Example 3)
Adhesive as in Example 1 except that 20 parts by mass of tris (acryloxyethyl) isocyanurate (trade name “Aronix M-315”, manufactured by Toagosei Co., Ltd.) of the adhesive composition A was changed to 10 parts by mass. Composition C was prepared to produce a double-sided PSA sheet.

Example 4
Adhesive as in Example 1 except that 20 parts by mass of tris (acryloxyethyl) isocyanurate (trade name “Aronix M-315”, manufactured by Toagosei Co., Ltd.) of the adhesive composition A was changed to 5 parts by mass. Composition D was prepared to produce a double-sided PSA sheet.

(Example 5)
Except that the second base film was changed to a polyethylene terephthalate (PET) film (thickness 38 μm, arithmetic average roughness Ra: 45 nm, maximum protrusion height Rp: 935 nm) having the same front and back roughness, the same as in Example 1 Similarly, a double-sided PSA sheet was prepared.

(Example 6)
Except that the second base film was changed to a polyethylene terephthalate (PET) film (thickness 38 μm, arithmetic average roughness Ra: 15 nm, maximum protrusion height Rp: 159 nm) having the same roughness on the front and back sides, Similarly, a double-sided PSA sheet was prepared.

(Comparative Example 1)
A double-sided PSA sheet was prepared in the same manner as in Example 1 except that the PSA composition was changed to the following.

  In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 99.0 parts by mass of n-butyl acrylate, 1.0 part by mass of 4-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate And 0.08 part by mass of 2,2′-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 60 ° C., reacted for 16 hours, and then cooled to room temperature. Here, GPC measurement of a part of the obtained solution was performed by the method described later, and the production of a polymer (B) having a mass average molecular weight of 1.6 million was confirmed. To 100 parts by mass (solid content) of the polymer (B), 0.15 parts by mass of a polyisocyanate-based crosslinking agent (trade name “Takenate D-110N” manufactured by Mitsui Chemicals, Inc.) and a silane coupling agent (Shin-Etsu Chemical Co., Ltd.) "KBM-403" manufactured) 0.1 parts by mass was added and mixed with toluene as a solvent to adjust the solid content to 15% by mass to prepare an adhesive composition E.

(Comparative Example 2)
A double-sided PSA sheet was prepared in the same manner as in Example 1 except that the PSA composition was changed to the following.

  In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 77.0 parts by mass of n-butyl acrylate, 20.0 parts by mass of methyl acrylate, 3.0 parts by mass of acrylic acid, 200 parts by mass of ethyl acetate and 0.08 parts by mass of 2,2′-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 60 ° C., reacted for 16 hours, and then cooled to room temperature. Here, a part of the obtained solution was subjected to GPC measurement, and production of a polymer (C) having a mass average molecular weight of 1.6 million was confirmed. 100 parts by mass (solid content) of the above polymer (C), 2 parts by mass of a polyisocyanate-based cross-linking agent (manufactured by Nippon Polyurethane, trade name “Coronate L”), an aluminum chelate-based cross-linking agent (manufactured by Soken Chemical Co., Ltd., trade name) "M-5A" 1.5 parts by mass) and 0.1 parts by mass of a silane coupling agent ("KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.) were added to and mixed with toluene as a solvent to obtain a solid content. Was adjusted to 15% by mass to prepare an adhesive composition F.

(Comparative Example 3)
Adhesive in the same manner as in Example 1 except that 20 parts by mass of tris (acryloxyethyl) isocyanurate (trade name “Aronix M-315”, manufactured by Toagosei Co., Ltd.) of the adhesive composition A was changed to 3 parts by mass. Composition G was prepared to produce a double-sided PSA sheet.

  In addition, the surface of the 2nd base film side of the 1st peeling film used for the double-sided adhesive sheet of each Example and a comparative example and the 2nd peeling film (surface on the opposite side to the surface which contact | connects an adhesive layer) The arithmetic average roughness Ra and the maximum protrusion height Rp were measured according to JIS B 0601-1994 using a surface roughness measuring instrument SV3000S4 (stylus type) manufactured by Mitutoyo Corporation.

  In addition, the proportion of the unevenness outside the range of ± 0.2 μm from the reference surface on the surface of the pressure-sensitive adhesive layer side of the first release film and the second release film used in the double-sided pressure-sensitive adhesive sheet of each Example and Comparative Example is Using the optical interference type surface shape observation device “Wyko NT-1100” [manufactured by Veeco Co., Ltd.], stitching was performed at 2.5 magnifications in the VSI mode, and the obtained surface shape image in the range of 4 × 4 mm To binarize the image with a portion outside the range of ± 0.2 μm from the reference surface and a portion within the range of ± 0.2 μm, and the unevenness of the portion outside the range of ± 0.2 μm from the reference surface The area ratio was calculated.

  Moreover, the peeling force with respect to the adhesive layer of the 1st peeling film and the 2nd peeling film in the double-sided adhesive sheet of each Example and each comparative example is based on JIS-Z0237, temperature is produced after producing a double-sided adhesive sheet. After curing for 7 days under the conditions of 23 ° C. and 50% relative humidity, the film was cut into a width of 20 mm and a length of 200 mm, and the first release film or the second film with the adhesive layer fixed using a tensile tester. The peeled film was measured by pulling it in the 180 ° direction at a speed of 300 mm / min.

Moreover, after curing the double-sided PSA sheets of each Example and each Comparative Example immediately after production and immediately after production under conditions of a temperature of 23 ° C. and a relative humidity of 50%, the pressure-sensitive adhesive layer was sampled to a size of 80 mm × 80 mm. Then, it was wrapped in a polyester mesh (mesh size 200) and the weight of the adhesive alone was weighed with a precision balance. The weight at this time is M1. The pressure-sensitive adhesive was immersed in an ethyl acetate solvent using a Soxhlet (extractor), refluxed and treated for 16 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried in an environment of a temperature of 23 ° C. and a relative humidity of 50% for 24 hours, and further dried in an oven at 80 ° C. for 12 hours. The weight of only the pressure-sensitive adhesive after drying was weighed with a precision balance. The weight at this time is M2. The gel fraction is expressed as (M2 / M1) × 100 (%).
These results are shown in Table 1.

  Moreover, after producing the double-sided adhesive sheet of each Example and each comparative example, after curing for 7 days on the conditions of temperature 23 degreeC and 50% of relative humidity, the 1st surface (1st peeling film side) of an adhesive layer And about each of the 2nd surface (2nd peeling film side), the area occupation rate of the unevenness | corrugation outside the range of +/- 0.2 micrometer from the reference surface was measured. If the surface of the pressure-sensitive adhesive layer is smooth, the value is close to 0%. Using an optical interference surface shape observation apparatus “Wyko NT-1100” [manufactured by Veeco Co., Ltd.], stitching was performed at 2.5 magnifications in the VSI mode. From the obtained surface shape image in the range of 4 × 4 mm, the image is binarized with a portion outside the range of ± 0.2 μm from the reference plane and a portion within the range of ± 0.2 μm, and from the reference plane The area ratio occupied by the unevenness in the portion outside the range of ± 0.2 μm was calculated. The results are shown in Table 2.

[2] Evaluation The following evaluation was performed on the double-sided PSA sheet obtained as described above.

[2.1] Evaluation of damaged skin on first surface of adhesive layer (visual observation)
After producing the double-sided PSA sheet of each example and each comparative example, it was cured for 7 days under conditions of a temperature of 23 ° C. and a relative humidity of 50%. Subsequently, the 2nd peeling film of each double-sided adhesive sheet was peeled off, and the exposed adhesive layer was bonded to the black acrylic board (made by Mitsubishi Rayon Co., Ltd.). Thereafter, the first release film is peeled off, and the light from the fluorescent lamp is reflected and observed. When the reflected fluorescent lamp image looks undistorted, the appearance is good (◯), and when it appears distorted, the appearance is poor ( X).

[2.2] Evaluation of damaged skin on second surface of adhesive layer (visual observation)
After producing the double-sided PSA sheet of each example and each comparative example, it was cured for 7 days under conditions of a temperature of 23 ° C. and a relative humidity of 50%. Next, the second release film of each double-sided pressure-sensitive adhesive sheet is peeled off, placed on a black acrylic board (manufactured by Mitsubishi Rayon Co., Ltd.) with the exposed pressure-sensitive adhesive layer facing up, and the light from the fluorescent lamp is reflected. It was judged that the appearance was good (O) when the image of the fluorescent lamp that was observed and reflected was not distorted, and that the appearance was poor (X) when it was distorted.

[2.3] Crying separation evaluation The double-sided PSA sheet of each Example and each Comparative Example was made into a roll form having a width of 500 mm, and after the double-sided PSA sheet was prepared, it was cured for 7 days under conditions of a temperature of 23 ° C and a relative humidity of 50%. Next, when the second release film of each double-sided pressure-sensitive adhesive sheet was peeled off 10 m at a peel rate of 10 m / min and a peel angle of 90 °, the presence or absence of transfer of the adhesive to the second release film was visually observed. Confirmation was made based on the following evaluation criteria.

○: No transfer to the second release film ×: Generation of transfer to the second release film These results are shown in Table 2.

As is apparent from Table 2, the double-sided pressure-sensitive adhesive sheet of the present invention prevented the generation of crushed skin. Moreover, the double-sided pressure-sensitive adhesive sheet of the present invention prevents the occurrence of crying separation.
On the other hand, satisfactory results were not obtained in the comparative example.

DESCRIPTION OF SYMBOLS 1 Double-sided adhesive sheet 10 Adhesive layer 101 1st surface 102 2nd surface 11 1st release film 111 1st release agent layer 112 1st base film 12 2nd release film 121 2nd release agent Layer 122 Second substrate film

Claims (5)

An adhesive layer comprising a first surface and a second surface;
A first release film adhered to the first surface of the pressure-sensitive adhesive layer;
A second release film adhered to the second surface of the pressure-sensitive adhesive layer,
The peeling force from the pressure-sensitive adhesive layer of the second release film is smaller than the peeling force from the pressure-sensitive adhesive layer of the first release film,
The pressure-sensitive adhesive layer is formed using a pressure-sensitive adhesive containing an active energy ray-curable resin,
The gel fraction immediately after formation of the pressure-sensitive adhesive layer is 70% or more,
When the gel fraction immediately after formation of the pressure-sensitive adhesive layer is X [%] and the gel fraction of the pressure-sensitive adhesive layer 7 days after the formation of the pressure-sensitive adhesive layer is Y [%], X / Y ≧ 0.9 relationship is satisfied,
The ratio of the unevenness outside the range of ± 0.2 μm from the reference surface in the first surface and the second surface of the pressure-sensitive adhesive layer is 20% or less.   The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the storage elastic modulus of the pressure-sensitive adhesive layer at 23 ° C after 7 days from the formation of the pressure-sensitive adhesive layer is 0.15 MPa or more.   The arithmetic average roughness Ra of the surface opposite to the surface in contact with the adhesive layer of the first release film and the second release film is 50 nm or less, and the maximum protrusion height Rp is 1000 nm or less. The double-sided pressure-sensitive adhesive sheet according to claim 1 or 2.   When the peel force from the pressure-sensitive adhesive layer of the first release film is X [mN / 25 mm] and the peel force from the pressure-sensitive adhesive layer of the second release film is Y [mN / 25 mm], X The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 3, which satisfies a relationship of -Y≥5.   A wound body obtained by winding the double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 4.

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