TW201437319A - Double-faced pressure-sensitive adhesive sheet - Google Patents

Abstract

A double-faced pressure-sensitive adhesive sheet of the present invention includes a pressure sensitive adhesive layer having a first surface and a second surface, a first release film allowed to adhere to the first surface of the pressure sensitive adhesive layer, a second release film allowed to adhere to the second surface of the pressure sensitive adhesive layer. A storage elastic modulus of the pressure sensitive adhesive layer at 23 DEG C is 0.3 MPa or more. A peel force of the second release film from the pressure sensitive adhesive layer is weaker than a peel force of the first release film from the pressure sensitive adhesive layer. The second release film is constituted so that an arithmetic average roughness Ra2 of a surface to make a contact with the pressure sensitive adhesive layer is 30 nm or less and a roughness Rp2 of maximum profile peak height of the surface is 250 nm or lower. It is possible for such a double-faced pressure-sensitive adhesive sheet to prevent bubbles (laminated bubbles) from generating between the second release film and the pressure sensitive adhesive layer with exhibiting superior durability.

Description

Double-sided adhesive sheet

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

An optical functional film system such as a polarizing plate is fixed to a member such as a liquid crystal cell by using a double-sided adhesive sheet made of an adhesive. Wherein, the double-sided adhesive sheet is manufactured, for example, by applying an adhesive on the first release film to form a coating film, and then bonding the second release film to the formed coating film, and then irradiating The coating film is cured by ultraviolet rays or the like to form an adhesive layer.

However, an adhesive for fixing use of an optical functional film such as a polarizing plate is required to have extremely high durability (light resistance, heat resistance, etc.). For example, an adhesive having a high-modulus modulus (storage elastic modulus of 0.3 MPa or more at 23 ° C) may be used in combination with an ultraviolet curable resin (for example, refer to Patent Document 1, Japanese Patent) Publication No. 2003-203822). This is due to the following reasons. The optical functional film body such as the polarizing plate to be produced is easily contracted by heat or the like, and the optical functional film body is shrunk due to thermal history. As a result, the adhesive layer in which the optical film bodies are stacked cannot follow the shrinkage stress, and the layer peeling at the interface is liable to occur. However, if a high elastic modulus adhesive is used, Suppress this contraction.

When such a high elastic modulus adhesive is formed into a double-sided adhesive sheet, when the second release film is bonded to the coating film of the adhesive on the first release film, There is a problem of bubbles (laminated bubbles) between the two release films and the adhesive layer. Further, after lamination (laminate), the coating film is cured by irradiation with an active energy ray such as ultraviolet rays, and the laminated bubbles are maintained in shape. Therefore, there is a possibility that bubbles are mixed when the double-sided adhesive sheet is attached to the optical functional film body, resulting in poor appearance and low yield.

SUMMARY OF THE INVENTION An object of the present invention is to provide a double-sided adhesive sheet which, while optimizing its durability, also prevents bubbles (laminated bubbles) from occurring between the second release film and the adhesive layer.

The object is achieved by the present invention of (1) to (4) below.

(1) A double-sided adhesive sheet comprising an adhesive layer, a first release film, and a second release film. The adhesive layer has a first surface and a second surface. The first release film is attached to the aforementioned first surface of the aforementioned adhesive layer. A second release film is attached to the aforementioned second surface of the adhesive layer. The storage elastic modulus of the adhesive layer at 23 degrees Celsius is 0.3 MPa or more. The release force of the second release film peeled off from the adhesive layer is smaller than the release force of the first release film peeled off from the adhesive layer. The arithmetic mean roughness Ra ₂ of the surface of the second release film contacting the adhesive layer is 30 nm or less, and the maximum protrusion height Rp ₂ of the surface of the second release film contacting the adhesive layer is 250 nm. the following.

The duplex of (2) above (1) an adhesive sheet, wherein the first arithmetic average roughness Ra of the surface from the shape of the membrane in contact with the adhesive layer ₁ of 40nm or less and the first shape from the film The maximum protrusion height Rp ₁ of the surface in contact with the above-mentioned adhesive layer is 700 nm or less.

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

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

According to the present invention, it is possible to provide a double-sided adhesive sheet which can have an optimized durability when used for attaching an optical functional film such as a polarizing plate, and can prevent air bubbles from occurring between the second release film and the adhesive layer ( Laminated bubbles).

1‧‧‧Double-sided adhesive sheet

10‧‧‧Adhesive layer

101‧‧‧ first surface

102‧‧‧ second surface

11‧‧‧First release film

111‧‧‧First release agent layer

112‧‧‧First substrate film

12‧‧‧Second release film

121‧‧‧Second release agent layer

122‧‧‧Second substrate film

Fig. 1 is a side sectional view showing the double-sided adhesive sheet of the present invention.

The invention will be described in detail below with reference to preferred embodiments.

The double-sided adhesive sheet will be described below.

The double-sided adhesive sheet of the present invention is used, for example, to bond an optical functional film such as a polarizing plate to a member such as a liquid crystal cell.

Fig. 1 is a side sectional view showing the double-sided adhesive sheet of the present invention.

As shown in FIG. 1, the double-sided adhesive sheet 1 includes an adhesive layer 10, a first release film 11, and a second release film 12. The adhesive layer 10 has a first surface 101 and a second surface 102. The first release film 11 is disposed on the first surface 101 of the adhesive layer 10. The second release film 12 is disposed on the second surface 102 of the adhesive layer 10.

In the configuration of the double-sided adhesive sheet of the present invention, the storage elastic modulus of the adhesive layer at 23 degrees Celsius is 0.3 MPa or more, and the release force of the second release film peeled off from the adhesive layer is smaller than the first one. The release force of the release film peeled off from the aforementioned adhesive layer. Further, the arithmetic mean roughness Ra ₂ of the surface of the second release film which is in contact with the adhesive layer is 30 nm or less, and the maximum protrusion height Rp ₂ of the surface of the second release film which is in contact with the adhesive layer is 250 nm or less. Thereby, even in the case of the adhesive layer having a high storage modulus, it is possible to effectively prevent bubbles (laminated bubbles) from occurring between the second release film and the adhesive layer.

In addition, when the storage elastic modulus of the adhesive layer is 0.3 MPa or more, the size of the optical functional film such as a polarizing plate can be more reliably suppressed with time.

Furthermore, the release force by the second release film peeling off from the adhesive layer is smaller than the release force of the first release film peeled off from the adhesive layer, thereby preventing the transfer from being called crying separation. When the phenomenon occurs, when the second release film is peeled off from the adhesive layer, one part of the adhesive layer is also attached to the second release film, and the adhesive layer does not remain in the first state in a smooth appearance. The phenomenon on the film.

Moreover, in the present specification, the release from the adhesive layer is released. Force, the force of the force measured as follows.

The measurement of the release force is carried out according to Japanese Industrial Standards JIS-Z0237, and the double-sided adhesive sheet is cut into a width of 25 mm and a length of 200 mm, and a tensile tester is used in the state of fixing the adhesive layer. This was carried out by stretching the release film in a direction of 180 degrees at a speed of 300 mm per minute.

Further, in the present specification, the storage elastic modulus of the adhesive layer is formed by stacking an adhesive having a thickness of 30 μm into a cylindrical test piece having a diameter of 8 mm and a thickness of 3 mm by a torsional shear method and the following Conditionally determined storage elastic modulus.

Measuring device: Dynamic viscoelasticity measuring device "DYNAMICANALYZER RDA II" manufactured by Rheometric, frequency: 1 Hz, temperature: 23 degrees Celsius, 80 degrees Celsius.

Hereinafter, each layer constituting the double-sided adhesive sheet 1 of the present embodiment will be described in detail.

The adhesive layer 10 will be described below.

The adhesive layer 10 has a first surface 101 and a second surface 102.

The storage elastic modulus of the adhesive layer 10 at 23 degrees Celsius is 0.3 MPa or more. Thereby, the size of the optical functional film body such as a polarizing plate can be suppressed from changing with time.

Here, although the storage elastic modulus of the adhesive layer 10 at 23 degrees Celsius is 0.3 MPa or more, it is preferably 0.35 to 12 MPa. By doing this, it is more certain The size of the optical functional film such as a polarizing plate is suppressed from varying with time, and the adhesion durability is also improved.

The adhesive constituting the adhesive layer 10 is not particularly limited, but it is preferable to use an adhesive which irradiates an active energy ray to an adhesive material, and the adhesive material contains (A) an acryl-based copolymer and (B) Active energy ray hardening type compound. Thereby, the storage elastic modulus of the adhesive layer 10 can be increased, and the durability (heat resistance, low temperature resistance, moisture resistance, and the like) of the adhesive layer 10 can be further improved.

The propylene-based copolymer (A) can be a (meth)acrylic acid ester-based copolymer. Here, in the present specification, (meth) acrylate means both acrylate and (meth) acrylate. Other similar terms are the same.

The (meth)acrylate copolymer is preferably a crosslinking point which can be crosslinked by various crosslinking methods. The (meth) acrylate-based copolymer having such a crosslinking point is not particularly limited, and an appropriate copolymerization can be arbitrarily selected from (meth) acrylate-based copolymers which are conventionally used as a resin component of an adhesive. Use it for use.

The (meth) acrylate copolymer having such a crosslinking point is preferably a copolymer having an alkyl group having 1 to 20 carbon atoms in the ester moiety. A copolymer of an alkyl (meth)acrylate, a monomer having a crosslinkable functional group in the molecule, and another monomer used as needed. Wherein the alkyl group of the ester moiety has 1 to 20 (meth)acrylic groups Alkyl esters, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate , butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, (methyl) Cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, Decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, (methyl) One or a combination of two or more kinds of palmityl (meth) acrylate and stearyl (meth) acrylate is preferred.

On the other hand, a monomer having a crosslinkable functional group in the molecule is preferably 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, and (methyl). ) 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate (3- Hydroxybutyl (meth)acrylate) and (meth)acrylic acid hydroxy alkyl ester (4-hydroxybutyl(meth)acrylate); Acetyl monomethylamide Monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate and Monoalkylaminoalkyl (meth)acrylate, such as monoethylaminopropyl (meth)acrylate; acrylic acid, methacrylic acid, crotonic acid , 2-butenoic acid), maleic acid (maleic acid), itaconic acid (methylene succinic acid), and citraconic acid (methyl succinyl acid) An acid ethylenic unsaturation carboxylic acid. These monomers may be used singly or in combination of two or more.

In the adhesive material, the copolymerization form of the (meth) acrylate copolymer (A) is not particularly limited, and may be any random, block, graft copolymer. .

Further, the (meth) acrylate-based copolymer (A) preferably has a mass average molecular weight of 500,000 or more, more preferably 600,000 to 2,000,000, and more preferably 700,000 to 1,800,000. Thereby, it is possible to have sufficient tightness and adhesion durability with the adherend, and it is possible to more effectively prevent the occurrence of floating and peeling of the adhesive layer 10. Here, the mass average molecular weight is a value obtained by measuring a (meth)acrylate copolymer (A) by a gel permeation chromatography (GPC) method and converting it into a standard polystyrene. The value.

In addition, the (meth) acrylate copolymer has intramolecular The content of the monomer unit of the crosslinkable functional group is preferably 0.01 to 10% by mass. When the content is 0.01% by mass or more, the crosslinking can be sufficiently carried out by a reaction between a crosslinking agent and a crosslinkable functional group described later, and the durability is good. On the other hand, when the content is 10% by mass or less, the crosslinkability is too high, so that the suitability for the liquid crystal glass unit and the retardation film is not low. If the durability and the suitability for the liquid crystal glass unit and the phase difference plate are considered, the preferred content of the monomer unit having the crosslinkable functional group is 0.05 to 7.0% by mass, and more preferably 0.2 to 6.0. The mass percentage is preferred.

Among them, one type or a combination of two or more types of materials may be used as the (meth) acrylate type copolymer (A).

Among the adhesive materials, a polyfunctional (meth)acrylate monomer having a molecular weight of less than 1,000 can be used as the active energy ray-curable compound (B).

For example, a polyfunctional (meth) acrylate monomer having a molecular weight of less than 1,000 may be one or a combination of two or more materials: 1,4-butanediol di(methyl) 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate ) acrylate (neopentylglycol di (meth) acrylate), polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di(meth) acrylate (neopentylglycol) Adipate di(meth)acrylate), hydroxy pivalic acid neopentylglycol Di(meth)acrylate), dicyclopentanyl di(meth)acrylate, dicyclopentenyl di(meth)acrylate Modified with caprolactone), phosphoric acid di(meth)acrylate modified with ethylene oxide, di(acryloxyethyl) Isocyanurate) and a difunctional type such as allylating cyclohexyl di(meth)acrylate; trimethylol propane tri(meth) Acrylate), dipentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate modified with propionic acid, pentaerythritol tris (a) Pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tris(meth)acrylate (trimethylol propane tri(meth)acrylate modified with propylene oxide) a trifunctional type such as tris(acryloxyethyl)isocyanurate; diglycerine tetra(meth)acrylate and pentaerythritol tetra(pentaerythritol tetra(meth)acrylate (pentaerythritol tetra(meth)acrylate) Tetrafunctional methic acid, etc.; Dipentaerythritol hexa(meth)acrylate) and caprolactone denatured dipentaerythritol hexa(meth)acrylate (dipentaerythritol hexa (meth)acrylate modified with caprolactone) and the like. Among them, in the above polyfunctional (meth)acrylate monomer, a monomer having a cyclic structure as a skeleton structure may be preferably used. The annular structure may be a carbon ring structure or a heterocyclic structure, and may have a single ring structure or a multi-ring structure. Such a polyfunctional (meth) acrylate monomer is, for example, an isocyanurate such as bis(acryloyloxyethyl)isocyanurate or tris(propylene oxyethyl)isocyanurate ( Hexahydrophthalic acid diacrylate modified with ethylene oxide , tricyclodecane dimethanol acrylate, neomethyl glycol propane diacrylate modified with neopentylglycol and adamantane diacrylate.

Further, an active energy ray-curable acrylate oligomer can be used as the active energy ray-curable compound (B). The acrylate-based oligomer preferably has a mass average molecular weight of 50,000 or less. Such acrylate-based oligomers are, for example, polyester acrylate oligomers, epoxy acrylate oligomers, and urethane acrylate oligomers. , polyether acrylate oligomers, polybutadiene acrylate oligomers and silicone acrylates Acrylate is a material such as an oligomer.

Among them, the polyester acrylate-based oligomer can obtain, for example, a polyester oligomer having a hydroxyl group at both terminals by condensing a polyvalent carboxylic acid and a polyvalent alcohol, and esterifying the hydroxyl group thereof with (meth)acrylic acid. Alternatively, or obtained by, for example, esterification of (meth)acrylic acid with a hydroxyl group at the terminal of the oligomer obtained by adding an alkylene oxide to a polyvalent carboxylic acid. The epoxy acrylate-based oligomer can be, for example, ethylene oxide by reacting (meth)acrylic acid with a lower molecular weight bisphenol epoxy resin or a novolak epoxy resin. The (oxirane) ring is obtained by carrying out an esterification reaction. Further, as the epoxy acrylate-based oligomer, a carboxyl-denatured epoxy acrylate oligomer partially denatured with a bis-carboxylic carboxylic acid anhydride can also be used. A urethane acrylate oligomer can be, for example, a polyurethane oligomer obtained by reacting a polyether polyol or a polyester polyol with a polyisocyanate. Polyurethane oligomer is obtained by esterification reaction with (meth)acrylic acid. A polyol acrylate oligomer can be obtained by esterifying a hydroxyl group of a polyether polyol with (meth)acrylic acid.

The mass average molecular weight of the above acrylate-based oligomer is a value measured by a GPC method and converted by a standard polymethyl methacrylate (PMMA), preferably 50,000 or less, and 500 to 50,000. Better, even better, choose a range of 3,000 to 40,000.

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

Further, an adduct acrylate-based polymer in which a group having a (meth)acryl fluorenyl group is introduced into a side chain can be used as the active energy ray-curable compound (B). Such an adduct type acrylate-based polymer can be used by using a (meth) acrylate described in the (meth) acrylate-based copolymer (A) and a monomer having a crosslinkable functional group in the molecule. The copolymer is obtained by reacting a compound having a (meth) acrylonitrile group and having a group reactive with a crosslinkable functional group, as a part of a crosslinkable functional group of the copolymer. The mass average molecular weight of the adduct type acrylate-based polymer is usually from 500,000 to 2,000,000 in terms of standard polystyrene.

In addition, one of the polyfunctional acrylate-based monomer, the acrylate-based oligomer, and the adduct-type acrylate-based polymer may be appropriately selected and used as the active energy ray-curable compound (B). You can choose between two or more.

In the adhesive material, the content ratio of the (meth) acrylate-based copolymer (A) and the active energy ray-curable compound (B) is 100:1 to 100 in terms of the performance of the obtained adhesive. : 100 is better, preferably 100:5~100:50, and 100:10~100:40 is better.

Among them, in the adhesive material, a photopolymerization initiator may be included depending on the demand.

The photopolymerization initiator may also be, for example, benzoin or benzene. Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin Benzoin isobutyl ether, acetophenone, dimethylamino acetophenone, 2,2-dimethoxy-2-phenylacetophenone (2,2-dimethoxy) -2-phenyl acetophenone), 2,2-diethoxy-2-phenyl acetophenone, 2-hydroxy-2-methyl-1-phenylpropane 2-hydroxy-2-methyl-1-phenyl propane-1-one, 1-hydroxy cyclohexyl phenyl ketone, 2-methyl-1-[4 -(methylthio)phenyl]-2-morpholinopropane-1-one, 4-(2-hydroxyl-[2-(methylthio)phenyl]-2-morpholinopropane-1-one) Ethyl oxy) phenyl-2-(hydroxy-2-propyl) ketone, benzophenone , p-phenyl benzophenone, 4,4'-diethylamino benzophenone, dichlorodiphenyl ketone Ro-benzophenone), 2-methyl anthraquinone, 2-ethyl anthraquinone, 2-tertiary-butyl anthraquinone, 2- 2-amino anthraquinone, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2-chlorothioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone, benzyl dimethyl ketal Acetophenone dimethyl ketal (acetophenone dimethyl ketal), p-dimethylaminobenzoate, oligomeric [2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl Acetone] (Oligo [2-hydroxy-2-methyl-1-[4-(1-methyl vinyl)phenyl]propanone]) and 2,4,6-trimethylbenzylidene-diphenyl-oxidation One or a combination of two or more materials may be used for materials such as phosphine (2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide).

Further, in the adhesive material, the content of the photopolymerization initiator is preferably 0.2 to 20 parts by mass based on 100 parts by mass of the active energy ray-curable compound (B).

Further, in the adhesive material, a crosslinking agent may be contained according to the demand.

The crosslinking agent is not particularly limited, and an appropriate acrylonitrile-based adhesive can be arbitrarily selected from among the acryl-based adhesives conventionally used as a crosslinking agent in the acryl-based adhesive. Such a crosslinking agent may also be, for example, a polyisocyanate compound, an epoxy resin, a melamine resin, a urea resin, a dialdehyde type, a methylol polymer, or aziridine. One or a combination of two or more kinds of materials, such as a compound, a metal chelate compound, an alkoxide, and a metal salt. Among these materials, it is preferred to use a polyisocyanate compound as a crosslinking agent.

The polyisocyanate compound can be an aromatic polyisocyanate such as tolylene diisocyanate, diphenyl methane diisocyanate or xylylene diisocyanate, or hexamethylene diene. Isocyanate A material such as an aliphatic polyisocyanate such as hexamethylene diisocyanate, an isophorone diisocyanate, an alicyclic polyisocyanate such as hydrogenated diphenyl methane diisocyanate, or a biuret thereof Biuret) body, isocyanurate body, even with ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane An adduct obtained by reacting a low molecular weight active hydrogen-containing compound such as castor oil.

The amount of the crosslinking agent added is preferably 0.01 to 20 parts by mass, and preferably 0.1 to 10 parts by mass, per 100 parts by mass of the (meth) acrylate-based copolymer (A).

Further, in the adhesive material, a silane coupling agent may be contained depending on the demand. When the optical functional film such as a polarizing plate is bonded to, for example, a liquid crystal glass unit or the like by containing the decane coupling agent, the adhesion between the adhesive and the glass unit is improved. The decane coupling agent is an organic hydrazine compound having at least one alkoxysilyl group in the molecule, which has good mutual solubility with the adhesive component and has light transmissivity, and is preferably transparent, for example.

The adhesive amount of the decane coupling agent is preferably 0.001 to 10 parts by mass, and preferably 0.005 to 5 parts by mass, for the adhesive material having a solid content of 100 parts by mass.

A specific example of a decane coupling agent is vinyl trimethoxy decane. (vinyl trimethoxy silane), vinyl triethoxy silane, and methacyloxy propyl trimethoxy silane, etc., containing a polymerizable unsaturated group, 3 3-glycidoxy propyl trimethoxy silane and 2-(3,4-epoxycyclohexane)ethyltrimethoxy decane (2-(3,4-epoxycyclohexyl) Ethylene compound such as ethyl trimethoxy silane), 3-aminopropyl trimethoxy silane, N-(2-aminoethyl)-3-aminopropyltrimethoxydecane (N-(2-aminoethyl)-3-aminopropyl trimethoxy silane) and N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane (N-(2-aminoethyl)-3-aminopropyl A material such as an amino group-containing fluorene compound or 3-chloropropyl trimethoxy silane. These materials may be used alone or in combination of two or more.

In the adhesive material, various additives commonly used in acrylonitrile-based adhesives such as tackifiers, antistatic agents, antioxidants, and ultraviolet absorbers can be added as needed within the range not impaired by the object of the present invention. , light stabilizers, softeners and fillers and other materials.

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

The active energy ray may be radiation such as ultraviolet rays and electron beams. The above ultraviolet rays can be obtained by a lamp such as a high pressure mercury lamp, an electrodeless lamp, or a xenon lamp. Furthermore, the electron beam can be obtained by means of an electron beam accelerator or the like.

Among the active energy rays, ultraviolet rays are particularly preferably used. Further, in the case of using an electron beam, an adhesive can be formed without adding a photopolymerization initiator.

The amount of irradiation of the active energy ray to the adhesive material is appropriately selected in such a manner as to obtain an adhesive having the storage elastic modulus as described above, but in the case of ultraviolet light, the illuminance is 50 to 1000 mW per square centimeter, and the amount of light is It is preferably 50 to 1000 mJ per square centimeter, and preferably 10 to 1000 krad in the case of an electron beam.

The average thickness of the adhesive layer 10 is preferably 3 to 10 μm, more preferably 4 to 8 μm. The average film thickness of the adhesive layer 10 falls within this range, and can be suitably applied to the thickness of a thin display.

The first release film will be described below.

The first release film 11 is attached to the first surface 101 of the adhesive layer 10.

This first release film 11 has a function of protecting the adhesive layer 10.

As shown in Fig. 1, the first release film 11 is formed by stacking the first release agent layer 111 and the first base material film 112 from the surface position in contact with the adhesive layer 10 to form a stacked body.

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

The material constituting the first base film 112 may be various synthetic resins, for example, a polybutylene terephthalate (PBT) resin or a polyethylene terephthalate (PET) resin. And polyethylene naphthalate (PEN) A polyester resin such as a resin is preferred, and a polyethylene terephthalate resin is preferably used. The first base film 112 may be a single layer film, or may be a multilayer film of two or more layers composed of the same or different materials.

In addition, the first base film 112 may also contain a filler. The filler may be, for example, a material such as silica, titania, calcium carbonate, kaolin, and alumina.

Although the thickness of the first base film 112 is not particularly limited, it is preferably 10 to 300 μm, and more preferably 15 to 200 μm.

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

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

The first release agent is not particularly limited and may be an alkyd compound, a propylene oxime compound, a silicone compound, a long-chain alkyl group-containing compound, or a fluorine. Materials such as compounds. Among these materials, an alkyd compound, an acrylonitrile compound, an anthrone compound, or a compound having a long-chain alkyl group is preferably used as the first release agent.

As the alkyd compound, an alkyd compound having a crosslinked structure is usually used. For example, the formation of the alkyd compound layer having a crosslinked structure can be a method of heating and hardening a layer formed of an alkyd compound, a crosslinking agent, and a thermosetting composition containing a curing catalyst as required. . Furthermore, alkyd compounds It may also be a denatured product such as a long-chain alkene-modified alkyd compound or an anthrone-modified alkyd compound.

As the propylene oxime compound, a propylene oxime compound having a crosslinked structure is usually used. Among them, the propylene oxime compound may be a denatured product such as a long-chain olefin-modified acryl oxime compound or an fluorenone-modified acryl oxime compound.

The anthrone-based compound may be an anthrone-based compound containing polydimethyl siloxane as a basic skeleton. The anthrone-based compound contains a compound such as an addition reaction type anthrone type compound, a condensation reaction type anthrone type compound, an ultraviolet curing type anthrone type compound, and an electron beam curing type anthrone type compound. Compared with the condensation reaction type anthrone type compound, the addition reaction type anthrone type compound has high reactivity and can optimize productivity, and has the advantages of little change in the release force after production and no hardening and shrinkage.

Specifically, the above-described addition reaction type fluorenone compound may be an organopolysiloxane having two or more such as a vinyl group or an allyl group at a molecular terminal and/or a side chain. Alkenyl having 2 to 10 carbon atoms, such as (allyl), propenyl or hexenyl. When such an addition reaction type anthrone compound is used, a crosslinking agent and a catalyst can also be used together.

The above cross-linking agent is, for example, an organopolyoxyalkylene having a hydrogen atom bonded to at least two deuterium atoms in one molecule, specifically, for example, dimethyl hydrogen siloxy-terminated Dimethyl siloxane - methyl hydrogen siloxane Copolymer, trimethyl siloxy-terminated dimethyloxane-methylhydroquinoxane copolymer, trimethyl siloxy-terminated methyl hydrogen polyfluorene A substance such as methyl hydrogen polysiloxane or poly (hydrogen silsesquioxane).

Further, the catalyst may be particulate platinum, particulate platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefinic complex of chloroplatinic acid, palladium, ruthenium. A platinum-based metal compound such as (rhodium). By using such a catalyst, the hardening reaction of the composition for forming a release agent layer can be performed more efficiently.

The long-chain alkyl group-containing compound is, for example, a polyvinylamino group obtained by reacting a long-chain alkyl isocyanate having a carbon number of 8 to 30 in a polyvinyl alcohol-based polymer. A polyvinyl carbamate, and an alkylurea derivative obtained by, for example, using a long-chain alkyl isocyanate having a carbon number of 8 to 30 in polyethyleneimine (PEI).

As the fluoride, a compound such as a fluorine silicone compound or a boron compound can be used.

In the composition for forming the first release agent layer, an additive may be appropriately mixed. The additives may be materials such as catalysts, dyes, and dispersants.

In the first release agent layer 111, the material of the first release agent layer forming composition is appropriately selected in such a manner that the release force of the first release film 11 is greater than the release force of the second release film 12. .

In the case where an anthrone compound is used as the first release agent, it is preferred to add an MQ resin in an appropriate amount as a heavy release controlling agent.

The first release agent composition may also suitably contain a dispersant or a solvent for the viscosity at the time of coating to fall within an appropriate range.

The dispersant or solvent is aromatic hydrocarbons such as toluene, fatty acid esters such as ethyl acetate, and methyl ethyl ketone (MEK). It is preferably an organic solvent such as a ketone or an aliphatic hydrocarbon such as hexane or heptane.

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

Among them, the coating method can be, for example, a gravure coat method, a bar coat method, a spray coat method, a spin coat method, an air knife coat method, and a roll. a method of a roll coat method, a blade coat method, a gate roll coat method, a die coat method, or the like, wherein a gravure coating method and a bar coating method are preferred, and a rod is used. The coating method is especially good.

Further, the drying temperature is not particularly limited, preferably 100 to 150 degrees Celsius, 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 μm, and particularly preferably 0.03 to 3 μm.

The arithmetic mean roughness Ra ₁ of the surface of the first release film 11 in contact with the adhesive layer 10 is preferably 40 nm or less, and the maximum protrusion height Rp ₁ is preferably 700 nm or less. Thereby, the adhesion (adhesiveness) between the first surface 101 of the adhesive layer 10 and the adherend such as the liquid crystal cell can be further improved. As a result, the durability of the optical product such as the liquid crystal panel finally obtained can be further improved. Moreover, it is possible to prevent the visibility from being lowered due to the uneven state of the first surface 101 of the adhesive layer 10.

The second release film will be described below.

The second release film 12 is attached to the second surface 102 of the adhesive layer 10.

This second release film 12 has a function of protecting the adhesive layer 10.

In the present invention, the arithmetic mean roughness Ra ₂ of the surface of the second release film 12 in contact with the adhesive layer 10 is preferably 30 nm or less, and the maximum protrusion height Rp ₂ is preferably 250 nm or less. Thereby, even in the case of the above-mentioned film and the adhesive layer 10 having a high storage elastic modulus, it is possible to effectively prevent bubbles (laminated bubbles) from occurring between the second release film 12 and the adhesive layer 10.

As shown in Fig. 1, the second release film 12 is formed by stacking the second release agent layer 121 and the second base film 122 in this order from the surface contact with the adhesive layer 10.

The second base film 122 can use the same material as that of the first base film 112 described in the item of the first release film 11 described above.

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

The second release agent can be used in the project of using the first release film described above. The same material as the first release agent.

In the second release agent layer 121, the second release agent layer forming composition is appropriately selected in such a manner that the release force of the second release film 12 is smaller than the release force of the first release film 11. material.

The second release agent layer 121 may have only one layer, or may have two or more layers, and it is preferable to use one layer for simplifying the operation.

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

When the release force of the first release film 11 peeled off from the adhesive layer 10 is expressed as X [mN / 25 mm], and the release force of the second release film 12 peeled off from the adhesive layer 10 is expressed as Y [mN When it is /25 mm], it is preferable to satisfy the relationship of XY≧5, and it is preferable to satisfy the relationship of XY≧10. Thereby, the occurrence of the transfer phenomenon called crying separation can be more effectively prevented, and when the second release film is peeled off from the adhesive layer, a part of the adhesive layer is also attached to the second release. Membrane phenomenon.

The present invention has been described in detail above based on preferred embodiments, but the present invention is not limited thereto.

The embodiment will be described below.

Next, a specific embodiment of the double-sided adhesive sheet relating to the present invention will be explained.

The production of the double-sided adhesive sheet will be described below.

Embodiment 1 will be explained below.

The production of the first release film will be described below.

The first release agent layer-forming composition A having the following composition was applied to the polyethylene terephthalate as the first substrate film by a bar coater so as to have a thickness of 0.1 μm after drying. One of the surfaces of the (PET) film (thickness: 38 μm) was continuously dried at 120 ° C for 1 minute to provide a first release agent layer. Thereby, a first release film is produced. 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 are shown in Tables 1-1 to 1-2.

The preparation of the first release agent layer-forming composition A will be described below.

An anthrone resin solution (manufactured by Dow Corning Toray Co., Ltd., trade name "BY24-561") containing an organic polyoxyalkylene having a vinyl group and an organopolysiloxane having a hydrogenated hydrosilyl group is calculated as a solid content Taking 30 parts by mass and a vinyl-based MQ resin (manufactured by Dow Corning Toray Co., Ltd., trade name "SD7292"), 15 parts by mass of the solid content, and the above-mentioned solid content concentration is 1.0 mass% Dilute and mix in toluene solvent. To the solution, two parts by mass of a platinum catalyst (manufactured by Dow Corning Toray Co., Ltd., trade name "SRX-212") was added to prepare a first release agent layer-forming composition A.

The production of the second release film will be described below.

The second release agent layer-forming composition B having the following composition was applied to the polyethylene terephthalate as a second substrate film by a bar coater so as to have a thickness of 0.1 μm after drying. One of the surfaces of the (PET) film (thickness: 38 μm) was continuously dried at 120 ° C for 1 minute to provide a second release agent layer. Thereby, a second release film is produced. 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 are shown in Tables 1-1 to 1-2.

The preparation of the second release agent layer-forming composition B will be described below.

100 parts by mass of the fluorenone resin (manufactured by Shin-Etsu Chemical Co., Ltd.: trade name "KS-847H"), and 1 part by mass of a hardener (manufactured by Shin-Etsu Chemical Co., Ltd.: trade name "CAT-PL50T") The second release agent layer-forming composition B was prepared by diluting with toluene to prepare a solid content concentration of 1 by mass.

The production of the adhesive composition will be described below.

95 parts by mass of n-butyl acrylate, 5 parts by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate and 0.08 A mass fraction of 2,2' azobisisobutyronitrile-(2-2'-azobisisobutyronitrile) was placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube to obtain a reaction liquid. Next, the air in the reaction vessel was replaced with nitrogen. Under the nitrogen atmosphere, the reaction solution was heated to 60 ° C while stirring the reaction solution, and after reacting for 16 hours, the reaction solution was cooled to room temperature. At this time, a part of the obtained solution was measured by a GPC method, and it was confirmed that the produced polymer (A) had a mass average molecular weight of 1.6 million. To 100 parts by mass (solid content) of the above polymer (A), 20 parts by mass of tris(propylene oxyethyl) isocyanurate (manufactured by Toagosei Co., Ltd., trade name "ARONIX M-315" was added. , molecular weight: 423), 2 parts by mass of photopolymerization initiator (CIBA SPECIALTY CHAMICALS Manufactured under the trade name "IRGACURE 500"), 4 parts by mass of a polyisocyanate crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd., trade name "CORONATE L"), and 0.1 parts by mass of a decane coupling agent (Shin-Etsu Chemical Co., Ltd.) The industrial company manufactures "KBM-403") and mixes it to obtain a mixed liquid. In the mixture, the toluene as a solvent was further added to adjust the mass percentage of 15 to prepare the adhesive composition A.

The production of the double-sided adhesive sheet will be described below.

The adhesive composition A was applied onto the release agent layer of the first release film so as to have a thickness of 5 μm after drying, and dried at 90 ° C for 1 minute to form an adhesive layer. Next, the second release film is adhered to the adhesive layer in such a manner that the release agent layer of the second release film contacts the formed adhesive layer to obtain a stacked body. The laminating step is to adjust the lamination pressure between the silicone gum roll (glue hardness: 80) and the metal roll to 0.5 MPa and sandwich the stack between the two at normal temperature. Executed at a speed of 50m per minute. Next, ultraviolet rays (UV) were irradiated from below the first release film under the following conditions to prepare a double-sided adhesive sheet. Thereafter, the curing was continued for ten days under conditions of 23 degrees Celsius and 50% relative humidity.

The UV irradiation conditions will be explained below.

‧Using the electrodeless lamp H VALVE manufactured by FUSION.

‧ Illumination is 600mW per square centimeter, and the amount of light is 150mJ per square centimeter.

UV illuminance and light quantity measurement using EYEGRAPHICS "UVPF-36" manufactured.

Embodiment 2 will be described below.

A double-sided adhesive sheet was produced in the same manner as in the above Example 1, except that the average thickness of the adhesive layer was formed to be 3 μm.

Embodiment 3 will be explained below.

A double-sided adhesive sheet was produced in the same manner as in the above Example 1, except that the average thickness of the adhesive layer was formed to be 10 μm.

Embodiment 4 will be explained below.

In addition to changing 20 parts by mass of the adhesive composition A (propylene oxyethyl) isocyanurate (manufactured by Toagosei Co., Ltd., trade name "ARONIX M-315") to 10 parts by mass, The adhesive composition B was prepared in the same manner as in the above Example 1 to prepare a double-sided adhesive sheet.

Embodiment 5 will be explained below.

In addition to changing 20 parts by mass of the adhesive composition A (propylene oxyethyl) isocyanurate (manufactured by Toagosei Co., Ltd., trade name "ARONIX M-315") to 40 parts by mass, The adhesive composition C was prepared in the same manner as in the above Example 1 to produce a double-sided adhesive sheet.

Examples 6 and 7 will be described below.

In addition to changing the second base film, the numerical values of the arithmetic mean roughness Ra ₂ and the maximum protrusion height Rp ₂ of the surface of the release agent layer of the second release film as shown in Tables 1-1 to 1-2 are produced. A double-sided adhesive sheet was produced in the same manner as in the above Example 1 except for the two release films.

Embodiment 8 will be explained below.

In addition to changing 20 parts by mass of the adhesive composition A (propylene oxyethyl) isocyanurate (manufactured by Toagosei Co., Ltd., trade name "ARONIX M-315") to 7.5 parts by mass, The adhesive composition D was prepared in the same manner as in the above Example 1 to prepare a double-sided adhesive sheet.

Embodiment 9 will be explained below.

A double-sided adhesive sheet was produced in the same manner as in the above Example 1, except that the average thickness of the adhesive layer was formed to 2 μm.

Embodiment 10 will be explained below.

In addition to changing the first base film, the numerical values of 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 as shown in Tables 1-1 to 1-2 are produced. A double-sided adhesive sheet was produced in the same manner as in the above Example 1 except for the two release films.

Comparative Examples 1 and 2 will be described below.

In addition to changing the second base film, the numerical values of the arithmetic mean roughness Ra ₂ and the maximum protrusion height Rp ₂ of the surface of the release agent layer of the second release film as shown in Tables 1-1 to 1-2 are produced. A double-sided adhesive sheet was produced in the same manner as in the above Example 1 except for the two release films.

Comparative Example 3 will be described below.

In addition to changing 20 parts by mass of the adhesive composition A (propylene oxyethyl) isocyanurate (manufactured by Toagosei Co., Ltd., trade name "ARONIX M-315") to 5 parts by mass, The rest are the same as the foregoing embodiment 1. The adhesive composition E is prepared in a manner to produce a double-sided adhesive sheet.

Wherein, the first release film and the second release film of the double-sided adhesive sheet used in each of the examples and the comparative examples have arithmetic mean roughness Ra ₁ , Ra ₂ and maximum of the surface in contact with the adhesive layer; The protrusion heights Rp ₁ and Rp _{2 were} measured using a surface roughness measuring machine SV3000S4 (stylus type) manufactured by Mitutoyo Co., Ltd. and in accordance with Japanese Industrial Standard JIS B 0601-1994.

In addition, the storage elastic modulus of the adhesive layer of the double-sided adhesive sheet used in each of the examples and the comparative examples at 23 ° C was a viscoelasticity measuring instrument (manufactured by RHEOMETRIC Co., Ltd., according to Japanese Industrial Standard JIS K 7244). The name "DYNAMIC ANALAYZER" was measured by the torsional shear method under the following conditions.

‧ Sample form: cylindrical shape with a diameter of 8 mm and a thickness of 3 mm (made by stacking the adhesive layer and cutting it into a cylindrical shape).

‧ Measurement frequency: 1 Hz.

‧ Measurement temperature: 23 degrees Celsius.

In addition, the release force of each of the first release film and the second release film used in the double-sided adhesive sheets of the respective examples and the comparative examples for the adhesive layer was performed in accordance with Japanese Industrial Standard JIS-Z0237. The test was carried out by a test machine. In this measurement, the double-sided adhesive sheet is cut into a width of 25 mm and a length of 200 mm, and the first release film or the second is stretched in a direction of 180 degrees at a speed of 300 mm per minute in a state of fixing the adhesive layer. The method of leaving the film is performed.

The evaluation of each of the examples and the comparative examples will be described below.

Evaluation of the double-sided adhesive sheet obtained as described above was carried out below.

The evaluation of the laminated bubbles will be described below.

For the double-sided adhesive sheets of the respective examples and the comparative examples, the number of laminated bubbles (3 μm or more) generated in the field of view of 700 μm × 500 μm was counted using a digital microscope manufactured by KEYENC, and evaluated according to the following criteria.

The determination criteria will be explained below.

○: Laminated bubbles did not occur.

△: The number of stacked bubbles was less than ten.

×: 10 or more bubbles were stacked.

The evaluation of the transfer phenomenon (cry separation) will be described below.

The double-sided adhesive sheets of the respective examples and comparative examples were wound into a roll form having a width of 500 mm. Next, when the first release film was peeled off by 10 m under the conditions of a peeling speed of 10 m per minute and a peeling angle of 90 degrees, it was visually confirmed whether or not the adhesive was transferred to the first release film. As a result, the judgment is made based on the following criteria.

○: Not transferred to the first release film.

×: A case where the transfer to the first release film occurred.

The durability evaluation will be described below.

The first release film was pulled out from the double-sided adhesive sheets of the respective examples and the comparative examples to expose the adhesive layer. Next, the exposed adhesive layer is bonded to a polarizing plate which is a polarizing plate which integrates a polarizing film and a viewing angle widening film which are formed by a polarizing film having a disk-shaped liquid crystal layer. Using a cutting device (manufactured by Takino Seisakusho Co., Ltd.) SUPER CUTTER, PN1-600) The obtained polarizing plate with the adhesive layer was cut into a size of 233 mm × 309 mm. Next, the second release film is pulled to expose the adhesive layer. Next, the exposed adhesive layer was attached to an alkali-free glass (manufactured by CORNING, EAGLE XG) to obtain a sample. Thereafter, the sample was pressurized at 0.5 MPa and 50 degrees Celsius for 20 minutes by AUTOCLAVE (autoclave) manufactured by Kurihara Manufacturing Co., Ltd. After that, the sample was allowed to stand under the following conditions of endurance conditions. After 500 hours, the sample was observed with a magnifying glass of 10 times. Appearance changes are based on the following.

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

△: There was no defect in the portion of 0.6 mm or more from the outer peripheral end on the four sides of the sample.

×: At least 0.6 mm or more from the outer peripheral end portion of at least one of the four sides of the sample has an abnormal appearance of an adhesive such as an adhesive floating, an adhesive peeling, an adhesive foaming, and an adhesive wrinkle of 0.01 mm or more. .

The durability conditions will be explained below.

‧ 80 degrees Celsius and dry environment.

‧ 60 degrees Celsius and 90% relative humidity.

‧HS (1 hour cycle of minus 35 degrees Celsius and 70 degrees Celsius) environment.

The results are shown in Tables 1-1~1-2.

As is apparent from Tables 1-1 to 1-2, the double-sided adhesive sheet of the present invention prevents the occurrence of lamination bubbles. Moreover, the double-sided adhesive sheet of the present invention optimizes the separation of the individual release films Formality. Furthermore, the double-sided adhesive sheet of the present invention optimizes durability. On the contrary, the comparative example did not give satisfactory results.

1‧‧‧Double-sided adhesive sheet

10‧‧‧Adhesive layer

101‧‧‧ first surface

102‧‧‧ second surface

11‧‧‧First release film

111‧‧‧First release agent layer

112‧‧‧First substrate film

12‧‧‧Second release film

121‧‧‧Second release agent layer

122‧‧‧Second substrate film

Claims (4)

A double-sided adhesive sheet comprising: an adhesive layer having a first surface and a second surface; a first release film attached to the first surface of the adhesive layer; and a second release a film attached to the second surface of the adhesive layer; wherein the adhesive elastic layer has a storage elastic modulus of 0.3 MPa or more at 23 degrees Celsius; wherein the second release film is The release force of the adhesive layer is less than the release force of the first release film peeled off from the adhesive layer; wherein the arithmetic mean of the surface of the second release film contacting the adhesive layer The roughness Ra ₂ is 30 nm or less, and the maximum protrusion height Rp ₂ of the surface of the second release film in contact with the adhesive layer is 250 nm or less. The double-sided adhesive sheet according to claim 1, wherein an arithmetic mean roughness Ra ₁ of the surface of the first release film contacting the adhesive layer is 40 nm or less, and the first release film is adhered to the adhesive film. The maximum protrusion height Rp ₁ of the surface in contact with the agent layer is 700 nm or less. The double-sided adhesive sheet according to claim 1, wherein the adhesive layer has an average thickness of 3 to 10 μm. The double-sided adhesive sheet according to any one of claims 1 to 3, wherein the release force of the first release film peeled off from the adhesive layer is expressed as X [mN/25 mm], and the second When the release force of the release film peeled off from the adhesive layer is expressed as Y [mN / 25 mm], the relationship of XY ≧ 5 is satisfied.