KR20150138241A - Double-sided adhesive sheet - Google Patents

Abstract

The double-sided pressure-sensitive adhesive sheet of the present invention comprises a pressure-sensitive adhesive layer having a first side and a second side, a first release film adhered to the first side of the pressure-sensitive adhesive layer, and a second release film adhered to the second side of the pressure- It has a film. The storage elastic modulus of the pressure-sensitive adhesive layer at 23 占 폚 is 0.3 MPa or more. The peeling force of the second peeling film from the pressure sensitive adhesive layer is smaller than the peeling force of the first peeling film from the pressure sensitive adhesive layer. The second peeling film is constructed such that the arithmetic mean roughness (Ra ₂ ) of the surface in contact with the pressure-sensitive adhesive layer is 30 nm or less and the maximum protrusion height (Rp ₂ ) is 250 nm or less. Such a double-sided pressure-sensitive adhesive sheet is excellent in durability and prevents the generation of air bubbles (laminated air bubbles) between the second release film and the pressure-sensitive adhesive layer.

Description

Double-Sided Adhesive Sheet {DOUBLE-SIDED ADHESIVE SHEET}

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

The optical functional film such as a polarizing plate is fixed using a double-faced pressure-sensitive adhesive sheet composed of a member such as a liquid crystal cell and a pressure-sensitive adhesive. Further, the double-sided pressure-sensitive adhesive sheet can be produced, for example, by applying a pressure-sensitive adhesive on a first release film to form a coating film, curing the second release film on the coating film formed thereafter, .

Here, the pressure-sensitive adhesive to be used for fixing an optical functional film such as a polarizing plate requires very excellent durability (light resistance, heat resistance, etc.). For example, a high elasticity modulus (storage elastic modulus at 23 占 폚 of 0.3 MPa or more) using an ultraviolet curable resin in combination is used (see, for example, Japanese Patent Application Laid-Open No. 2003-203822). This is for the following reasons. The produced optically functional film such as a polarizing plate is likely to shrink due to heat or the like, so that the optically functional film shrinks due to thermal history. As a result, the pressure-sensitive adhesive layer for laminating the respective optical films does not follow the shrinkage stress, and the layer tends to be peeled from the interface. However, such shrinkage can be suppressed by using a pressure-sensitive adhesive having a high modulus of elasticity.

When a double-sided pressure-sensitive adhesive sheet having such a high modulus of elasticity is made thin, a problem that bubbles (laminated bubbles) are generated between the second release film and the pressure-sensitive adhesive layer when the second release film is stuck on the pressure-sensitive adhesive coating film on the first release film have. After lamination, the coating film is cured by irradiation with active energy rays such as ultraviolet rays, so that the laminated bubble maintains its shape. As a result, when the double-sided pressure-sensitive adhesive sheet is laminated with the optically functional film, bubbles are mixed therein, resulting in poor appearance, resulting in a reduction in yield.

Japanese Patent Application Laid-Open No. 2003-203822

An object of the present invention is to provide a double-sided pressure-sensitive adhesive sheet which is excellent in durability and which prevents bubbles (laminated bubbles) from being generated between the second peelable film and the pressure-sensitive adhesive layer.

The above object can be achieved by the following inventions (1) to (4).

(1) a pressure-sensitive adhesive layer having a first side and a second side;

A first release film adhered to the first surface of the pressure-sensitive adhesive layer; And

And a second peeling film adhered to the second surface of the pressure-sensitive adhesive layer,

The storage elastic modulus of the pressure-sensitive adhesive layer at 23 DEG C is 0.3 MPa or more,

The peeling force of the second peeling film from the pressure sensitive adhesive layer is smaller than the peeling force of the first peeling film from the pressure sensitive adhesive layer,

Wherein the second peelable film has an arithmetic mean roughness (Ra ₂ ) of 30 nm or less and a maximum protrusion height (Rp ₂ ) of 250 nm or less on the surface in contact with the pressure-sensitive adhesive layer.

(2) the first release film is less than the arithmetic mean roughness (Ra ₁₎ of the surface in contact with the pressure-sensitive adhesive layer 40nm and also double-sided pressure-sensitive adhesive according to (1) is configured that the maximum protruding height (Rp ₁₎ is less than or equal to 700nm Sheet.

(3) The double-sided pressure-sensitive adhesive sheet according to (1) or (2), wherein the pressure-sensitive adhesive layer has an average thickness of 3 to 10 μm.

(4) When X (mN / 25 mm) is the peeling force of the first peeling film from the pressure-sensitive adhesive layer and Y (mN / 25 mm) is the peeling force of the second peeling film from the pressure- Sensitive adhesive sheet according to any one of (1) to (3) above.

According to the present invention, there is provided a double-faced pressure-sensitive adhesive sheet which is used for adhering, for example, an optical functional film such as a polarizing plate and has excellent durability and prevents bubbles (laminated bubbles) from being generated between the second peelable film and the pressure- It is possible.

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

Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

"Double-sided adhesive sheet"

The double-sided pressure-sensitive adhesive sheet of the present invention is used for bonding an optical functional film such as a polarizing plate with a member such as a liquid crystal cell.

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

1, the double-sided pressure-sensitive adhesive sheet 1 comprises a pressure-sensitive adhesive layer 10 having a first side 101 and a second side 102 and a pressure-sensitive adhesive layer 10 provided on the first side 101 of the pressure- 1 release film 11 and a second release film 12 provided on the second surface 102 of the pressure-sensitive adhesive layer 10.

Sensitive adhesive sheet of the present invention is characterized in that the storage elastic modulus of the pressure-sensitive adhesive layer at 23 DEG C is 0.3 MPa or more and the peeling force of the second peeling film from the pressure-sensitive adhesive layer is smaller than the peeling force of the first peeling film from the pressure- . The second peeling film is characterized in that the arithmetic mean roughness (Ra ₂ ) of the surface in contact with the pressure-sensitive adhesive layer is 30 nm or less and the maximum protrusion height (Rp ₂ ) on the surface is 250 nm or less. This makes it possible to effectively prevent the occurrence of bubbles (lamellar air bubbles) between the second release film and the pressure-sensitive adhesive layer even in the case of the pressure-sensitive adhesive layer having a high storage modulus.

When the storage elastic modulus of the pressure-sensitive adhesive layer is set to 0.3 MPa or more, it is possible to more reliably suppress the change in the dimension of the optical functional film such as a polarizing plate over time.

When the peeling force of the second peeling film from the pressure-sensitive adhesive layer is made smaller than the peeling force of the first peeling film from the pressure-sensitive adhesive layer, a part of the pressure-sensitive adhesive layer adheres to the second peeling film And a smooth and good appearance of the pressure-sensitive adhesive layer on the first peeling film can not be remained, that is, a so-called interlayer uneven adhesion can be prevented from occurring.

In the present specification, the peeling force from the pressure-sensitive adhesive layer refers to the peeling force measured as follows.

The peeling force measurement can be carried out by cutting the double-sided pressure-sensitive adhesive sheet to a width of 25 mm and a length of 200 mm in accordance with JIS-Z0237 and pulling the release film in the direction of 180 ° at a speed of 300 mm / minute while fixing the pressure-sensitive adhesive layer using a tensile tester have.

In the present specification, the storage elastic modulus of the pressure-sensitive adhesive layer refers to the storage elastic modulus measured by the torsion shear method under the following conditions by laminating a pressure-sensitive adhesive having a thickness of 30 mu m to prepare a cylindrical specimen of 8 mm? X 3 mm in thickness.

Measuring device: Dynamic viscoelasticity measuring device "DYNAMIC ANALYZER RDAII" manufactured by Leo Matrix, frequency: 1 Hz, temperature: 23 ° C., 80 ° C.

Hereinafter, the layers constituting the double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment will be described in detail.

≪ Pressure-sensitive adhesive layer (10) >

The pressure-sensitive adhesive layer (10) has a first side (101) and a second side (102).

The pressure-sensitive adhesive layer (10) has a storage elastic modulus at 23 占 폚 of 0.3 MPa or more. As a result, it is possible to suppress the change over time of the optical functional film dimensions such as the polarizing plate.

Further, the storage elastic modulus of the pressure-sensitive adhesive layer 10 at 23 캜 is preferably 0.3 MPa or more, more preferably 0.35 to 12 MPa. As a result, it is possible to more reliably suppress the change with time in the dimension of the optical functional film such as the polarizing plate and improve the durability of the adhesion.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 10 is not particularly limited, but it is preferable to use a pressure-sensitive adhesive obtained by irradiating an active energy ray to a pressure-sensitive adhesive material containing an acrylic copolymer (A) and an active energy ray curable compound (B) . As a result, the storage elastic modulus of the pressure-sensitive adhesive layer 10 can be relatively increased, and the durability (heat resistance, low temperature resistance, moisture resistance, etc.) of the pressure-sensitive adhesive layer 10 can be further improved.

Examples of the acrylic copolymer (A) include (meth) acrylic acid ester copolymers. In the present specification, the term "(meth) acrylic acid ester" means both of an acrylic acid ester and a methacrylic acid ester. Other similar terms are also the same.

As the (meth) acrylic acid ester-based copolymer, it is preferable to have a crosslinking point capable of crosslinking according to various crosslinking methods. The (meth) acrylic ester-based copolymer having such a crosslinking point is not particularly limited, and any copolymer among the (meth) acrylic acid ester-based copolymer conventionally used as a resin component of the pressure-sensitive adhesive may be appropriately selected and used.

Examples of the (meth) acrylate-based copolymer having such a crosslinking point include a (meth) acrylic acid alkyl ester having an alkyl group of an alkyl group of an ester group in an amount of 1 to 20, a monomer having a crosslinkable functional group in the molecule and another monomer It is preferable to use a copolymer. Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl moiety of the ester moiety include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, (Meth) acrylate, dodecyl (meth) acrylate, dodecyl (meth) acrylate, isobutyl (meth) acrylate, isobutyl Stearyl (meth) acrylate, stearyl (meth) acrylate, and the like, or a combination of two or more of these may be used.

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 of the monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl and 4-hydroxybutyl (meth) acrylate; (Meth) acrylic acid monoalkylaminoalkyl such as monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate and monoethylaminopropyl (meth) acrylate; And ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. These monomers may be used alone or in combination of two or more.

In the adhesive material, there is no particular limitation on the type of copolymerization of the (meth) acrylate-based copolymer (A), and any of random, block, and graft copolymers may be used.

The (meth) acrylic acid ester-based copolymer (A) preferably has a mass average molecular weight of 500,000 or more, more preferably 600,000 to 2,000,000, and still more preferably 700,000 to 1,800,000. As a result, the adhesiveness with the adherend and the durability of adhesion are sufficient, and the occurrence of lifting and peeling of the pressure-sensitive adhesive layer 10 can be prevented more effectively. The mass average molecular weight is a standard polystyrene conversion value obtained by measuring the (meth) acrylic acid ester copolymer (A) by Gel Permeation Chromatography (GPC).

In the (meth) acrylate-based 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 mass%. When the content is 0.01% by mass or more, crosslinking is sufficient due to the reaction between the crosslinking agent and a crosslinkable functional group which will be described later, and durability is improved. On the other hand, if it is 10 mass% or less, the degree of crosslinking becomes too high, which is preferable because the adhesiveness to the liquid crystal glass cell or the retarder is not reduced. In view of durability and compatibility with the liquid crystal glass cell or the retardation plate, the content of the monomer unit having a crosslinkable functional group is more preferably 0.05 to 7.0 mass%, particularly preferably 0.2 to 6.0 mass%.

As the (meth) acrylic acid ester-based copolymer (A), one type may be used, or two or more types may be used in combination.

As the active energy ray-curable compound (B) in the sticky material, a polyfunctional (meth) acrylate-based monomer having a molecular weight of less than 1,000 can be used.

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 Acrylate, neopentyl glycol adipate di (meth) acrylate, neopentyl glycol di (meth) acrylate hydroxypivalate, dicyclopentanyl di (meth) acrylate, capro (Meth) acrylates such as lactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate, di (acryloxyethyl) isocyanurate, and arylated cyclohexyl di ; (Meth) acrylate, propylene oxide-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylolpropane tri (meth) acrylate, dipentaerythritol tri ) Acrylate, and tris (acryloxyethyl) isocyanurate; Tetrafunctional types such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; Pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate; And hexafunctional types such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. These may be used alone or in combination of two or more. Among the above-mentioned polyfunctional (meth) acrylate-based monomers, it is preferable to use monomers having a cyclic structure in the skeleton structure. The cyclic structure may be a carbon cyclic structure and a heterocyclic structure, or may be a monocyclic structure and a polycyclic structure. Examples of such multifunctional (meth) acrylate monomers include those having an isocyanurate structure such as di (acryloxyethyl) isocyanurate and tris (acryloxyethyl) isocyanurate, and those having an isocyanurate structure such as dimethyloldicyclopentane Diacrylate, ethylene oxide-modified hexahydrophthalic acid diacrylate, tricyclodecane dimethanol acrylate, neopentyl glycol-modified trimethylolpropane diacrylate, adamantane diacrylate, and the like can be preferably used.

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

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

The weight average molecular weight of the acrylate oligomer is preferably 50,000 or less, more preferably 500 to 50,000, and still more preferably 3,000 to 40,000 in terms of standard polymethylmethacrylate measured by GPC .

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

As the active energy ray curable compound (B), an acryl acrylate polymer in which a group having a (meth) acryloyl group is introduced into the side chain can be used. Such an acrylate-based polymer may be obtained by using a copolymer of the (meth) acrylic acid ester described in the (meth) acrylate-based copolymer (A) and a monomer having a crosslinkable functional group in the molecule, and the crosslinkable functional group Can be obtained by reacting a compound having a (meth) acryloyl group and a group capable of reacting with a crosslinkable functional group in a part thereof. The mass average molecular weight of the corresponding adduct acrylate polymer is usually 500,000 to 2,000,000 in terms of standard polystyrene.

As the active energy ray curable compound (B), one of the above-mentioned polyfunctional acrylate-based monomer, acrylate-based oligomer and adduct acrylate-based polymer may be selected and used, and two or more kinds thereof may be selected and used in combination .

The content ratio of the (meth) acrylic acid ester copolymer (A) and the active energy ray curable compound (B) in the adhesive material is preferably 100: 1 to 100: 100 in terms of mass ratio in view of the performance of the obtained pressure- : 5 to 100: 50, and still more preferably 100: 10 to 100: 40.

As the adhesive material, a photopolymerization initiator may be included if 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-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, 4- (2-hydroxyethoxy) phenyl- 2- , Benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methyl anthraquinone, 2-ethyl anthraquinone, 2-tert-butyl anthraquinone, , 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetophenone dimethylketal, p-Dimethylamino benzoic acid Ester, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, May be used alone or in combination of two or more.

The blending amount of the photopolymerization initiator in the viscous material is preferably 0.2 to 20 parts by mass based on 100 parts by mass of the active energy ray curable compound (B).

A crosslinking agent may be included in the adhesive material, if necessary.

The crosslinking agent is not particularly limited, and any acrylic pressure-sensitive adhesive may be suitably selected from acrylic pressure-sensitive adhesives conventionally used as a crosslinking agent in an acrylic pressure-sensitive adhesive. Examples of such a crosslinking agent include polyisocyanate compounds, epoxy resins, melamine resins, urea resins, diallydehydes, methylol polymers, aziridine compounds, metal chelate compounds, metal alkoxides and metal salts, Two or more species can be used in combination. Among them, 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 and hydrogenated diphenylmethane diisocyanate, Polyisocyanate and the like, and adducts which are reaction products of these burettes, isocyanurate compounds and low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane and castor oil .

The amount of the crosslinking agent to be added is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 10 parts by mass based on 100 parts by mass of the (meth) acrylic acid ester-based copolymer (A).

The adhesive material may contain a silane coupling agent if necessary. When the optical functional film such as a polarizing plate is attached to, for example, a liquid crystal glass cell or the like by containing the silane coupling agent, 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, and is highly compatible with the pressure-sensitive adhesive component and highly transparent, for example, substantially transparent to light.

The addition amount of the silane coupling agent is preferably 0.001 to 10 parts by mass, more preferably 0.005 to 5 parts by mass based on 100 parts by mass of the solid content of the viscous material.

Specific examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- ( Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N (3-aminopropyltrimethoxysilane) - (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, and 3-chloropropyltrimethoxysilane. These may be used singly or in combination of two or more kinds.

The adhesive material may contain various additives commonly used in acrylic pressure sensitive adhesives, for example, a tackifier, an antistatic agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a softening agent, Can be added.

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

Examples of the active energy ray include ultraviolet rays and electron rays. The ultraviolet ray can be obtained by 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, ultraviolet rays are particularly preferably used. When an electron beam is used, a pressure-sensitive adhesive can be formed without adding a photopolymerization initiator.

The active energy ray irradiation amount for the sticky material is suitably selected so that the pressure sensitive adhesive having the storage elastic modulus as described above can be obtained. However, in the case of ultraviolet rays, the illuminance is 50 to 1000 mW / cm ² and the light amount is 50 to 1000 mJ / cm ² . A range of 10 to 1000 krad is preferred.

The average thickness of the pressure-sensitive adhesive layer 10 is preferably 3 to 10 占 퐉, more preferably 4 to 8 占 퐉. By setting the average thickness of the pressure-sensitive adhesive layer 10 within this range, it is possible to make the thickness suitable for use in a thin display.

[First release film]

The first release film 11 is adhered 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 peeling film 11 is formed of a laminate in which a first peeling agent layer 111 and a first base film 112 are sequentially laminated from the side in contact with the pressure-sensitive adhesive layer 10.

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

As the material constituting the first base film 112, various synthetic resins may be used, but for example, polyester resins such as polybutylene terephthalate resin, polyethylene terephthalate resin and polyethylene naphthalate resin are preferably used, and polyethylene It is more preferable to use a terephthalate resin. Further, the first base film 112 may be a single layer, and may be a multilayer of two or more layers made of the same or different materials.

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

The thickness of the first base film 112 is not particularly limited, but is preferably 10 to 300 占 퐉, more preferably 15 to 200 占 퐉.

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

The first release agent layer 111 is formed by applying a composition for forming a first release agent layer containing the first release agent on the surface of the first base film 112 and drying the same.

Examples of the first releasing agent include an alkyd compound, an acrylic compound, a silicone compound, a compound containing a long-chain alkyl group, and a fluorine compound without any particular limitation. Among them, as the first releasing agent, it is preferable to use an alkyd compound, an acrylic compound, a silicone compound or a compound containing a long-chain alkyl group.

As the alkyd compound, an alkyd compound having a crosslinking structure is generally used. For the formation of the alkyd compound layer having a crosslinked structure, for example, a method of thermally curing a layer made of a thermosetting composition including an alkyd compound, a crosslinking agent and optionally a curing catalyst may be used. 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 crosslinking 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.

As the silicone compound, there can be mentioned a silicone compound having dimethylpolysiloxane as a basic skeleton. The silicon compound includes an addition reaction type silicone compound, a condensation reaction type silicone compound, an ultraviolet ray curable silicone compound, an electron ray curable silicone compound and the like. The addition reaction type silicone compound has high reactivity and is excellent in productivity and has advantages such as less change in peeling force after production compared with condensation reaction type silicon compound and no hardening shrinkage.

Specific examples of the addition reaction type silicone compound include an organopolysiloxane having at least two alkenyl groups having 2 to 10 carbon atoms such as a vinyl group, allyl group, propenyl group, and hexenyl group at the terminal and / or side chain of the molecule have. 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 organopolysiloxanes having a hydrogen atom bonded to at least two silicon atoms in one molecule, specifically, dimethylhydrogensiloxy end-blocked dimethylsiloxane methylhydrogensiloxane copolymer, trimethylsiloxy terminal endblocked dimethyl Siloxane methylhydrogensiloxane copolymer, trimethylsiloxy terminated methylhydrogenpolysiloxane, poly (hydrogenosilsesquioxane), and the like.

Examples of the catalyst include fine particulate platinum, particulate platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complex of chloroplatinic acid, palladium and rhodium. By using such a catalyst, the curing reaction of the composition for forming a release agent layer can proceed with higher efficiency.

Examples of the long chain alkyl group-containing compound include polyvinylcarbamates obtained by reacting a polyvinyl alcohol polymer with a long chain alkyl isocyanate having 8 to 30 carbon atoms or an alkyl component obtained by reacting polyethyleneimine with a long chain alkyl isocyanate having 8 to 30 carbon atoms Derivatives and the like are used.

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

Additives may be appropriately added to the first release agent composition. Examples of additives include catalysts, dyes, and dispersants.

The composition material for forming the first release agent layer is suitably selected so that the peeling force of the first release film 11 in the first release agent layer 111 becomes larger than the peeling force of the second release film 12.

When a silicone compound is used 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 suitably contain a dispersion medium or a solvent in order to adjust the viscosity at the time of application to a suitable range.

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.

Examples of the coating method include a gravure coating method, a bar coating method, a spray coating method, a spin coating method, an air knife coating method, a roll coating method, a blade coating method, a gate roll coating method, a die coating method, The coat method and the bar coat method are preferable, and the bar coat 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 0.01 to 5 탆, particularly preferably 0.03 to 3 탆.

The arithmetic mean roughness of the surface in contact with first adhesive layer 10 of the peel-off film (11) (Ra ₁₎ is 40nm or less and the other hand is preferably not more than its maximum projected height (Rp ₁₎ 700nm. This makes it possible to further improve the adhesion (adhesion) between the first surface 101 of the pressure-sensitive adhesive layer 10 and an adherend such as a liquid crystal cell. As a result, the durability of an optical product such as a liquid crystal panel finally obtained can be further improved. Further, the visibility of the first surface 101 of the pressure-sensitive adhesive layer 10 can be prevented from lowering due to the unevenness.

[Second Release Film]

The second release film 12 is adhered to the second surface 102 of the pressure-sensitive adhesive layer 10.

The second peeling film 12 has a function of protecting the pressure-sensitive adhesive layer 10.

In the present invention, it is less than the second pressure-sensitive adhesive layer 10 and the arithmetic average roughness of the surface (Ra ₂₎ is 30nm or less in contact with the other hand and that the maximum protruding height (Rp ₂₎ of the release film (12) 250nm. This makes it possible to effectively prevent the occurrence of bubbles (lamellar air bubbles) between the second peelable film 12 and the pressure-sensitive adhesive layer 10 even when the thin film element or the pressure-sensitive adhesive layer 10 having a high storage elastic modulus as described above have.

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

As the second base film 122, the same material as the first base film 112 described in the first release film 11 may be used.

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

As the second release agent, the same material as the first release agent described in the first release film 11 can be used.

The material of the composition for forming the second release agent layer is suitably selected so that the peeling force of the second release film 12 in the second release agent layer 121 is smaller than the peeling force of the first release film 11. [

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 탆, more preferably 0.03 to 3 탆.

The peeling force of the first peeling film 11 from the pressure sensitive adhesive layer 10 is X [mN / 25 mm] and the peeling force of the second peeling film 12 from the pressure sensitive adhesive layer 10 is Y [mN / 25 mm] , It is more preferable that the relation of X < RTI ID = 0.0 > 5 < / RTI > This makes it possible to more effectively prevent the occurrence of an electrodeposition phenomenon called so-called interlayer uneven adhesion in which a part of the pressure-sensitive adhesive layer adheres to the second release film when the second release film is peeled from the pressure-sensitive adhesive layer.

Although the present invention has been described in detail with reference to the preferred embodiments thereof, the present invention is not limited thereto.

Example

Next, specific examples of the release film according to the present invention will be described.

[1] Production of double-sided pressure-sensitive adhesive sheet

(Example 1)

1. Fabrication of first release film

A composition (A) for forming a first release agent layer having the following composition was dried on one side of a polyethylene terephthalate (PET) film (thickness: 38 mu m) as a first base film and applied with a bar coater so as to have a thickness of 0.1 mu m, For 1 minute to provide a first release agent layer. Thus, a first release film was produced. Table 1 shows the arithmetic mean roughness (Ra ₁ ) and the maximum protrusion height (Rp ₁ ) of the surface of the first release agent layer of the obtained first release film.

(Preparation of composition (A) for forming first release agent layer)

30 parts by mass of a silicone resin solution (trade name "BY24-561 ", trade name; manufactured by Toray Dow Corning Co., Ltd.) containing an organopolysiloxane having a vinyl group and an organopolysiloxane having a hydrosilyl group in terms of solid content and 30 parts by mass of an MQ resin 15 parts by mass in terms of solid content) was diluted and mixed in a toluene solvent so that the solid concentration became 1.0% by mass. To this solution was added 2 parts by mass of a platinum-based catalyst (trade name "SRX-212", manufactured by Toray Industries, Inc.) to prepare a composition (A) for forming a first release agent layer.

2. Fabrication of second release film

A composition (B) for forming a second release agent layer having the following composition was dried on one side of a polyethylene terephthalate (PET) film (thickness: 38 mu m) as a second base film and applied with a bar coater so as to have a thickness of 0.1 mu m, For one minute to provide a second release agent layer. Thus, a second release film was produced. Table 1 shows the arithmetic mean roughness (Ra ₂ ) and the maximum protrusion height (Rp ₂ ) of the surface of the second release agent layer of the obtained second release film.

(Preparation of Composition (B) for Second Release Agent Layer)

100 parts by mass of a silicone resin (trade name: "KS847H", manufactured by Shin-Etsu Chemical Co., Ltd.) and 1 part by mass of a curing agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "CAT-PL50T") were diluted with toluene to form a second release agent layer having a solid content concentration of 1% (B) was prepared.

3. Preparation of pressure-sensitive adhesive composition

A reaction vessel equipped with a stirrer, a hygrometer, a reflux condenser, a dropping device, and a nitrogen introduction tube was charged with 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 parts by mass of isobutyronitrile were injected to obtain a reaction solution. Then, air in the reaction vessel was replaced with nitrogen gas. While stirring the reaction solution in the nitrogen atmosphere, the temperature of the reaction solution was raised to 60 占 폚 and allowed to react for 16 hours, and then the reaction solution was cooled to room temperature. A part of the obtained solution was subjected to GPC measurement to confirm formation of polymer (A) having a mass average molecular weight of 1,600,000. 20 parts by mass of tris (acryloxyethyl) isocyanurate (Aronix M-315, trade name, manufactured by TOAGOSEI Co., Ltd., molecular weight: 423) was added to 100 parts by mass (solid content) of the polymer (A) , 4 parts by mass of a polyisocyanate crosslinking agent (trade name: Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.) and a silane coupling agent (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) ") Were added and mixed to obtain a mixed solution. Toluene was added as an additional solvent to the mixed solution, and the solid content was adjusted to 15 mass% to prepare a pressure-sensitive adhesive composition (A).

4. Manufacture of double-sided adhesive sheet

The pressure-sensitive adhesive composition (A) was dried on the release agent layer of the first release film to a thickness of 5 mu m and dried at 90 DEG C for 1 minute to form a pressure-sensitive adhesive layer. Subsequently, the second release film was laminated on the pressure-sensitive adhesive layer so that the release agent layer of the second release film was in contact with the pressure-sensitive adhesive layer to obtain a laminate. The bonding was carried out at a rate of 50 m / min under a room temperature condition by inserting a laminate between a silicone rubber roll (rubber hardness: 80) in which the laminate pressure was adjusted to 0.5 MPa and a metal roll. Then, ultraviolet rays (UV) were irradiated under the first peeling film under the following conditions to produce a double-sided pressure-sensitive adhesive sheet. Thereafter, it was cured for 10 days under conditions of a temperature of 23 캜 and a relative humidity of 50%.

<UV irradiation condition>

· Electrodeless lamp H valve is used by Fusion company.

Light intensity: 600 mW / cm ² , light quantity: 150 mJ / cm ²

UV light intensity meter "UVPF-36" manufactured by Eyegraphics Co., Ltd. was used.

(Example 2)

A double-faced pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the average thickness of the pressure-sensitive adhesive layer was 3 占 퐉.

(Example 3)

A double-sided pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the average thickness of the pressure-sensitive adhesive layer was 10 占 퐉.

(Example 4)

Except that 20 parts by mass of tris (acryloxyethyl) isocyanurate (manufactured by TOAGOSEI Co., Ltd., trade name "Aronix M-315") of the pressure-sensitive adhesive composition (A) was changed to 10 parts by mass. B) was prepared to prepare a double-sided pressure-sensitive adhesive sheet.

(Example 5)

Except that 20 parts by mass of tris (acryloxyethyl) isocyanurate (Aronix M-315, trade name, manufactured by TOAGOSEI CO., LTD.) Of 40 parts by mass was used as the pressure-sensitive adhesive composition (A) C) was prepared to prepare a double-sided pressure-sensitive adhesive sheet.

(Examples 6 and 7)

Except that the second release film was changed so that the arithmetic average roughness (Ra ₂ ) and the maximum protrusion height (Rp ₂ ) of the surface of the release agent layer of the second release film were the values shown in Table 1 A double-faced pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. [

(Example 8)

Except that 20 parts by mass of tris (acryloxyethyl) isocyanurate (Aronix M-315, trade name, manufactured by TOAGOSEI CO., LTD.) Of 7.5 parts by mass was used as the pressure-sensitive adhesive composition (A) (D) was prepared to prepare a double-sided pressure-sensitive adhesive sheet.

(Example 9)

A double-sided pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the average thickness of the pressure-sensitive adhesive layer was 2 占 퐉.

(Example 10)

Except that the first release film was changed so that the arithmetic mean roughness (Ra ₁ ) and the maximum protrusion height (Rp ₁ ) of the surface of the release agent layer of the first release film were as shown in Table 1, A double-faced pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. [

(Comparative Examples 1 and 2)

Except that the second release film was changed so that the arithmetic average roughness (Ra ₂ ) and the maximum protrusion height (Rp ₂ ) of the surface of the release agent layer of the second release film were the values shown in Table 1 A double-faced pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. [

(Comparative Example 3)

Except that 20 parts by mass of tris (acryloxyethyl) isocyanurate (manufactured by TOAGOSEI Co., Ltd., trade name "Aronix M-315") of the pressure-sensitive adhesive composition (A) E) was prepared to prepare a double-sided pressure-sensitive adhesive sheet.

In addition, each of Examples and Comparative Examples, the arithmetic mean roughness (Ra _1, Ra _2), the maximum protrusion height of the surface in contact with the pressure-sensitive adhesive layer of the first release film and a second release film used in the pressure sensitive adhesive double coated sheet (Rp _1, Rp ₂₎ Was measured in accordance with JIS B 0601-1994 using a surface roughness meter SV3000S4 (contact type) manufactured by Mitsutoyo Co., Ltd.

The storage elastic modulus of the pressure-sensitive adhesive layer used in the double-sided pressure-sensitive adhesive sheets of each of the examples and the comparative example was measured by a twist shearing method using a viscoelasticity measuring instrument (trade name: "DYNAMIC ANALAYZER" manufactured by REOMETRIC Co., Respectively.

Sample shape: Circumference of 8 mmφ × 3 mm (produced by laminating the pressure-sensitive adhesive layer and cutting it into a cylindrical shape).

· Measuring frequency: 1Hz

· Measuring temperature: 23 ℃

The peel strengths of the first peelable film and the second peelable film pressure-sensitive adhesive layer in the double-sided pressure-sensitive adhesive sheets of the respective Examples and Comparative Examples were measured using a tensile tester in accordance with JIS-Z0237. The measurement was carried out by cutting the double-sided pressure-sensitive adhesive sheet to a width of 25 mm and a length of 200 mm, and pulling the first release film or the second release film in the direction of 180 ° at a speed of 300 mm / minute while fixing the pressure-sensitive adhesive layer.

[2] Evaluation

The double-sided pressure-sensitive adhesive sheet thus obtained was evaluated as follows.

[2.1] Evaluation of Lamy Bubble

The double-faced pressure-sensitive adhesive sheets of each of the examples and comparative examples were counted by counting the number of laminar bubbles (3 μm or more) generated within the field of view of 700 μm × 500 μm using a KEYENCE digital microscope, and evaluated according to the following criteria.

· Measurement standards

○: Lamia bubbles were not generated.

?: Less than 10 laminar bubbles.

X: There were 10 or more laminar bubbles.

[2.2] Evaluation of electrodeposition phenomenon (interlayer imbalance adhesion)

The double-sided pressure-sensitive adhesive sheets of each of the examples and comparative examples were wound in the form of rolls having a width of 500 mm. Next, when the first peel film was peeled for 10 m under a condition of a peeling speed of 10 m / min and a peel angle of 90, whether or not the first peel film was electrodeposited was visually confirmed. The results were evaluated according to the following evaluation criteria.

?: There was no electrodeposition on the first release film.

X: Electrodeposition on the first release film occurred.

[2.3] Durability evaluation

The first release film was peeled off from the double-sided pressure-sensitive adhesive sheet of each example and each comparative example to expose the pressure-sensitive adhesive layer. Then, the exposed pressure-sensitive adhesive layer was bonded to a polarizing plate composed of a polarizing film made of a polarizing film with a discotic liquid crystal layer and a viewing angle expanding film. The resulting polarizer was cut into a size of 233 mm x 309 mm using a cutting device (super cutter, manufactured by Oginosei Co., Ltd., PN1-600). The second release film was then pulled off to expose the pressure-sensitive adhesive layer. Further, the exposed pressure-sensitive adhesive layer was bonded to a non-alkali glass (Eagle XG made by Corning Incorporated) to obtain a sample. Thereafter, the sample was pressurized at 0.5 MPa and 50 캜 for 20 minutes with an auto clave made by Kurihara Seisakusho Co., Ltd. (auto clave). Thereafter, the sample was allowed to stand under the conditions of the following durability conditions. After 500 hours, a sample was observed using a 10x magnifying glass.

The appearance change was based on the following.

 ○: There were no defects on the four sides of the sample.

 ?: There were no defects on the four sides of the sample at a position of 0.6 mm or more from the outer peripheral end.

 X: Adhesive appearance abnormality and defects of 0.1 mm or more, such as peeling of the adhesive, peeling of the adhesive, foaming of the adhesive, wrinkling of the adhesive, etc., were observed on at least one side of the sample at a distance of 0.6 mm or more from the outer edge.

&Lt; Durability condition &

· Drying at 80 ℃

· 60 ° C 90% RH

· HS (one hour cycle at -35 ° C and 70 ° C) environment

These results are shown together in Table 1.

As shown in Table 1, the double-sided pressure-sensitive adhesive sheet of the present invention was able to prevent the occurrence of lamellar bubbles. The double-sided pressure-sensitive adhesive sheet of the present invention was excellent in peelability of each release film. Further, the double-sided pressure-sensitive adhesive sheet of the present invention was excellent in durability. On the other hand, a satisfactory result could not be obtained in the comparative example.

The double-sided pressure-sensitive adhesive sheet of the present invention comprises a pressure-sensitive adhesive layer having a first side and a second side, a first release film adhered to the first side of the pressure-sensitive adhesive layer, and a second release film adhered to the second side of the pressure- It has a film. The pressure-sensitive adhesive layer storage elastic modulus at 23 占 폚 is 0.3 MPa or more. The peeling force of the second peeling film from the pressure sensitive adhesive layer is smaller than the peeling force of the first peeling film from the pressure sensitive adhesive layer. The second peeling film is constructed such that the arithmetic mean roughness (Ra ₂ ) of the surface in contact with the pressure-sensitive adhesive layer is 30 nm or less and the maximum protrusion height (Rp ₂ ) is 250 nm or less. Such a double-sided pressure-sensitive adhesive sheet is excellent in durability and prevents the generation of air bubbles (laminated air bubbles) between the second release film and the pressure-sensitive adhesive layer. Therefore, the present invention has industrial applicability.

1: double-sided pressure-sensitive adhesive sheet 10: pressure-sensitive adhesive layer
11: first peeling film 12: second peeling film
101: first side 102: second side
111: First release agent layer 112: First release film
121: second release agent layer 122: second base film

Claims (4)

A pressure-sensitive adhesive layer having a first side and a second side;
A first release film adhered to the first surface of the pressure-sensitive adhesive layer; And
And a second release film adhered to the second surface of the pressure-sensitive adhesive layer,
The storage elastic modulus of the pressure-sensitive adhesive layer at 23 DEG C is 0.3 MPa or more,
The peeling force of the second peeling film from the pressure sensitive adhesive layer is smaller than the peeling force of the first peeling film from the pressure sensitive adhesive layer,
The second release film has a pressure sensitive adhesive double coated sheet, characterized in that configured such that not more than 250nm arithmetic mean roughness (Ra ₂₎ is 30nm or less, while the maximum height of the protrusion (Rp ₂₎ of the surface in contact with the pressure-sensitive adhesive layer. The method according to claim 1,
Wherein the first peelable film has an arithmetic mean roughness (Ra ₁ ) of a surface contacting the pressure-sensitive adhesive layer of 40 nm or less and a maximum protrusion height (Rp ₁ ) of 700 nm or less. 3. The method according to claim 1 or 2,
Wherein the average thickness of the pressure-sensitive adhesive layer is 3 to 10 占 퐉. 4. The method according to any one of claims 1 to 3,
The relationship XY &amp;ge; 5 is satisfied when the peeling force of the first peelable film from the pressure sensitive adhesive layer is X [mN / 25 mm] and the peel force from the pressure sensitive adhesive layer of the second peelable film is Y [mN / 25 mm] A satisfactory double-sided pressure-sensitive adhesive sheet.

Images