WO2014080715A1

WO2014080715A1 - Substrate-less double-sided adhesive sheet

Info

Publication number: WO2014080715A1
Application number: PCT/JP2013/078494
Authority: WO
Inventors: 智久齋藤; 公裕井崎
Original assignee: 三菱樹脂株式会社
Priority date: 2012-11-22
Filing date: 2013-10-21
Publication date: 2014-05-30
Also published as: CN104781359B; KR101821257B1; TW201432012A; CN104781359A; KR20150087218A

Abstract

A substrate-less double-sided adhesive sheet (10) in which release films (31, 32) are laminated on each side of an adhesive layer (11) and the peel force of one release film (first release film) (31) is smaller than the peel force of the other release film (second release film) (32), wherein the second release film (32) simultaneously satisfies the following conditions (a) to (c). (a) A release film in which a release layer (25) is provided on a surface of a coating layer (24) which comprises a hydrolytic silicon compound provided on a biaxially oriented polyester film. (b) Variation in the angle of orientation in the film surface of the biaxially oriented polyester film is 6 degrees/500 mm or less. (c) The amount of oligomer extracted from the surface of the release layer (25) of the release film (32) by dimethylformamide is 0.5 mg/m² or less.

Description

Substrate-less double-sided adhesive sheet

The present invention relates to a substrate-less double-sided pressure-sensitive adhesive sheet, and is excellent in antistatic properties, mold release properties, oligomer sealing properties, and easy testability, and has good release properties without causing release charge at the time of release film release. Peelable. Further, after the application of the adhesive, after the release film is bonded, the fluctuation of peeling from the adhesive layer is small, and the migration and precipitation of the oligomer to the adhesive layer is as small as possible. For example, the present invention provides a substrate-less double-sided pressure-sensitive adhesive sheet suitable for various uses to be bonded via an adhesive layer, such as for producing a liquid crystal polarizing plate and for producing a capacitive touch panel.

Conventionally, various pressure-sensitive adhesive sheets for surface bonding between objects are known, and a base-less double-sided pressure-sensitive adhesive sheet is known as one of pressure-sensitive adhesive sheets. The substrate-less double-sided PSA sheet consists of a laminate structure in which a light release film with a relatively low peel strength and a heavy release film with a relatively high peel strength are laminated on both sides of the adhesive layer. After the removal, the double-sided pressure-sensitive adhesive sheet becomes only the pressure-sensitive adhesive layer having no supporting substrate.

As a method of using the substrate-less double-sided pressure-sensitive adhesive sheet, first, the light release film is peeled off, and one surface of the exposed pressure-sensitive adhesive layer is adhered to the object surface of the other side to be bonded, and after the adhesion, the heavy release film is further peeled off, A processing step in which the other surface of the exposed pressure-sensitive adhesive layer is bonded to a different object surface, whereby the objects are surface-bonded is exemplified.

In recent years, the baseless double-sided pressure-sensitive adhesive sheet has attracted attention because of its good workability, and its application is expanding. It is also used for members for various optical applications such as mobile phones. In particular, a capacitive touch panel is rapidly expanding its application as an information terminal by a multi-touch operation in which a screen operation is performed with two fingers. Capacitive touch panels tend to have a thicker printing step than the resistive film method, and therefore a proposal has been made to eliminate the printing step by thickening the adhesive layer. When the pressure-sensitive adhesive layer is made thick, when the release film is peeled off, a part of the pressure-sensitive adhesive layer adheres to the release film, or air bubbles are mixed into the part of the pressure-sensitive adhesive layer transferred to the release film. There was a case where a malfunction occurred. Therefore, when using a substrateless double-sided pressure-sensitive adhesive sheet for optical applications, not only the substrateless double-sided pressure-sensitive adhesive sheet but also the release film to be combined is more stringent than before, and a release film with higher quality is required. The situation is needed.

On the other hand, when using a release film, peeling electrification may occur when it is peeled off from the pressure-sensitive adhesive layer, and as a result, in the processing site, defects such as product defects due to adhesion or entrainment of foreign substances etc. may occur. There was a case.
For this reason, it is not always sufficient to take antistatic measures only by handling facilities in the manufacturing process, and there has been a strong demand for antistatic treatment from the release film itself. Furthermore, in a release film provided with a heavy release type release layer, there was a tendency for heavy release when peeled after a state of being bonded to an adhesive layer for a long time. As in the present invention, in an application where a release film is bonded through an adhesive layer, when the ratio of the peeling force is out of the desired range, it is difficult to peel off in a scene that originally needs to be peeled off. In some cases, such a problem occurs.

Furthermore, in a state where the pressure-sensitive adhesive layer is provided on the second release film (heavy release side), it may be bonded to the counterpart member and an inspection with optical evaluation may be performed. In that case, when an inspection is performed through an optical member having a polarizing action, the inspection visual field may become dark depending on the angle.

Japanese Patent Application No. 2010-56884 Japanese Patent Application No. 2010-121101 Japanese Patent Application No. 2010-97765 Japanese Patent Application No. 2010-97925 Japanese Patent Application No. 2010-165733 Japanese Patent Application No. 2011-48410 Japanese Patent Application No. 2011-75120

The present invention has been made in view of the above circumstances, and the problem to be solved is a substrate-less double-sided pressure-sensitive adhesive sheet in which release films are laminated on both sides of a pressure-sensitive adhesive layer, for example, a capacitance type Provided is a substrate-less double-sided pressure-sensitive adhesive sheet that is suitably used as a touch panel member, has antistatic properties, mold release properties, oligomer sealing properties, and good testability, and has a mold sealing performance in the release film itself. Is.

As a result of intensive studies in view of the above situation, the present inventors have found that according to the base material-less double-sided pressure-sensitive adhesive sheet having a specific configuration, the above problems can be easily solved, and the present invention has been completed. . The present invention comprises two related inventions, and the gist of each invention is as follows.

That is, the gist of the first invention is that release films are laminated on both sides of the pressure-sensitive adhesive layer, and the release force of one release film (first release film) is the other release film (second release film). A substrate-less double-sided pressure-sensitive adhesive sheet, wherein the second release film simultaneously satisfies the following conditions (a) to (c): Be on the sheet.
(A) A release film in which a release layer is provided on the surface of a coating layer containing a hydrolyzable silicon compound provided on a biaxially stretched polyester film.
(B) The variation of the orientation angle in the plane of the biaxially stretched polyester film is 6 degrees / 500 mm or less.
(C) The amount of oligomer extracted with dimethylformamide from the surface of the release layer of the release film is 0.5 mg / m ² or less.

The gist of the second invention resides in the base material-less double-sided pressure-sensitive adhesive sheet according to the first aspect, wherein the film haze of the first release film is 6% or more. .

The first invention is suitable as a substrate-less double-sided pressure-sensitive adhesive sheet used for a capacitive touch panel, for example, because it has an antistatic property, good releasability and oligomer sealing performance, and its industrial value is high. The second aspect of the invention further has good inspection ease and discrimination.

Typical sectional drawing which shows the base-material-free double-sided adhesive sheet which concerns on embodiment of this invention.

<First invention>
In the present invention, the polyester film constituting the first and second release films may have a single layer structure or a laminated structure. For example, the polyester film exceeds the gist of the present invention in addition to the two-layer or three-layer structure. As long as there is not, it may be a multilayer of four layers or more, and is not particularly limited.

In the present invention, the polyester used for the polyester film may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyester includes polyethylene terephthalate (PET) and the like. On the other hand, examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (eg, P-oxybenzoic acid). One or two or more types can be mentioned, and examples of the glycol component include one or more types such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like. In any case, the polyester referred to in the present invention refers to a polyester that is usually 60 mol% or more, preferably 80 mol% or more of polyethylene terephthalate or the like which is an ethylene terephthalate unit.

In the present invention, it is preferable to mix particles in the polyester layer mainly for the purpose of imparting slipperiness. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, it is possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed during the polyester production process.

On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

The average particle size of the particles used is usually in the range of 0.01 to 3 μm, preferably 0.01 to 1 μm. When the average particle diameter is less than 0.01 μm, the particles are likely to aggregate and dispersibility may be insufficient. On the other hand, when the average particle diameter exceeds 3 μm, the surface roughness of the film becomes too rough and There may be a problem when a release layer is applied in the process.

Furthermore, the particle content in the polyester layer is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the transparency of the film is insufficient. There is.

The method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage for producing the polyester constituting each layer, but the polycondensation reaction may proceed preferably after the esterification stage or after the transesterification reaction.

Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

The thickness of the polyester film constituting the first release film and the second release film of the present invention is not particularly limited as long as it can be formed as a film, but is usually 25 to 250 μm, preferably It is in the range of 38 to 188 μm, more preferably 50 to 125 μm.

Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all.
First, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method are preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the stretching temperature orthogonal to the first-stage stretching direction is usually 70 to 170 ° C., and the draw ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

Also, the simultaneous biaxial stretching method can be adopted for the production of the polyester film in the present invention. The simultaneous biaxial stretching method is a method in which the unstretched sheet is usually stretched and oriented simultaneously in the machine direction and the width direction in a state where the temperature is controlled at 70 to 120 ° C, preferably 80 to 110 ° C. The area magnification is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be employed.

Furthermore, a so-called coating stretching method (in-line coating) for treating the film surface during the above-described polyester film stretching step can be performed. When a coating layer is provided on a polyester film by a coating stretching method, coating can be performed simultaneously with stretching and the thickness of the coating layer can be reduced according to the stretching ratio, producing a film suitable as a polyester film. it can.

The coating layer constituting the release film in the present invention will be described.

The coating layer constituting the release film in the present invention has good antistatic properties and oligomer precipitation prevention properties, and is also hydrolyzable in order to improve the adhesion between the release layer and the polyester film over time. It is an essential requirement to contain a silicon compound.

As the hydrolyzable silicon compound used in the present invention, a compound represented by the general formula Si (OR ¹ ) x (R ² ) _4-x is preferably used for the purpose of the present invention. In the above general formula, x is preferably an integer of 2 to 4. In the above general formula, R ¹ may be either an alkyl group or an acyl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, a tert-butyl group and the like, an alkyl group having 1 to 5 carbon atoms, and an acyl group. Examples thereof include an acyl group having 1 to 4 carbon atoms such as an acetyl group. In the above general formula, R2 is an organic group having 1 to 10 carbon atoms, for example, an unsubstituted or substituted hydrocarbon group. The unsubstituted hydrocarbon group includes methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, tert-butyl group, n-hexyl group, cyclohexyl group, n-octyl group, tert- Examples thereof include alkyl groups such as octyl group and n-decyl group, aryl groups such as phenyl group, alkenyl groups such as vinyl group and allyl group. Examples of the substituted hydrocarbon group include γ-glycidoxypropyl group, γ-mercaptopropyl group, 3,4-epoxycyclohexylethyl group, γ-methacryloyloxypropyl group, and the like. These hydrolyzable silicon compounds may be used alone or in combination of two or more.

Specific examples of the hydrolyzable silicon compound with x = 4 include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-acetoxysilane and the like. Specific examples of x = 3 include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloyloxypropyltrimethoxy Silane, γ-mercaptopropyltriethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, 3,4-epoxycyclohexylethyltriethoxy Silane and the like. Examples of the alkoxysilane compound of x = 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, methylphenyldimethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane, Examples include di-i-propyldimethoxysilane, di-i-propyldiethoxysilane, diphenyldimethoxysilane, and divinyldiethoxysilane.

In addition, as a material constituting the coating layer in the present invention, it is preferable to use a metal element-containing organic compound in order to further improve the oligomer sealing property.

Specifically, at least one metal element-containing organic compound selected from aluminum, titanium, and zirconium may be contained in the coating layer.

Specific examples of the organic compound having an aluminum element include aluminum tris (acetylacetonate), aluminum monoacetylacetonate bis (ethylacetoacetate), aluminum-di-n-butoxide-monoethylacetoacetate, aluminum di- Examples include iso-propoxide monomethyl acetoacetate and the like.

Specific examples of the organic compound having titanium element include titanium orthoesters such as tetranormal butyl titanate, tetraisopropyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, tetramethyl titanate; titanium acetylacetonate, Examples thereof include titanium chelates such as titanium tetraacetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate, titanium triethanolamate, and titanium ethylacetoacetate.

Specific examples of the organic compound having a zirconium element include, for example, zirconium acetate, zirconium normal propylate, zirconium normal butyrate, zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium bisacetylacetonate and the like.

Among them, a metal element-containing organic compound selected from aluminum and zirconium is preferable, and an organic compound having a chelate structure is more preferable from the viewpoint of particularly good oligomer precipitation preventing performance. It is also described in detail in the “Crosslinking agent handbook” (Yamashita Shinzo, Kaneko Tosuke editor Taiseisha Co., Ltd., 1990 edition).

In the coating layer constituting the release film in the present invention, it is preferable to mix the hydrolyzable silicon compound (A) and the metal element-containing organic compound (B) in order to improve the oligomer sealing property. . The blending ratio (weight ratio) of both is preferably in the range of (A) :( B) = 1: 0.001 to 1: 0.01. When it is out of the range, the surface resistivity (R) of the surface of the release layer in the release film may not reach a desired level, or problems such as insufficient oligomer sealing performance may occur. .

Next, formation of the release layer in the present invention will be described.
The release layer constituting the first release film and the second release film in the present invention refers to a layer having releasability, and specifically, the peeling force between the acrylic pressure-sensitive adhesive tape and the release layer. The present invention can be completed by setting (F) within a certain range.

The peeling force of the first release film 31 corresponding to the light peeling side with respect to the adhesive layer 11 is preferably 5 to 40 mN / cm. When the peeling force of the first release film is less than 5 mN / cm, the release film may be easily peeled in a scene that does not need to be peeled. Moreover, when the peeling force of the first release film exceeds 40 mN / cm, a peeling phenomenon called “floating” occurs between the second release film and the adhesive layer in the step of peeling the first release film. There is.
By keeping the absolute value of the peeling force of the first release film 31 low, even if the absolute value of the peeling force of the second release film 32 is lowered, the difference in the peeling force between the

release films

31 and 32 is increased. It becomes possible. In addition, by setting the peeling force of the first release film 31 to a certain value or more, the first release film 31 is easily peeled from the adhesive layer 11 in a scene that does not need to be peeled before use. Or it becomes possible to prevent the phenomenon in which the 1st release film 31 floats from the adhesion layer 11. FIG.

On the other hand, the peeling force of the second release film 32 corresponding to the heavy peeling side is preferably 45 to 100 mN / cm, more preferably 50 to 80 mN / cm. When the peeling force of the second release film is less than 45 mN / cm, when the first release film is peeled off, there may be a problem that a part of the second release film is peeled off. Moreover, when the peeling force of a 2nd mold release film exceeds 100 mN / cm, malfunctions, such as the component derived from an adhesion layer remaining in a 2nd mold release film, may arise.
It is preferable that the base-material-less double-sided pressure-sensitive adhesive sheet of the present invention provides a difference in peel force between the first release film and the second release film in addition to the above-described peel force adjustment.
The peeling force of the second release film 32 is usually 2.0 times or more, preferably 3.0 times or more of the peeling force of the first release film 31. When the peeling force of the second release film 32 is less than 2.0 times the peeling force of the first release film 31, the second release film 32 adheres when the first release film 31 on the light release side is peeled off. In some cases, a phenomenon that the phenomenon of floating from the agent layer 11 occurs, the adhesive layer component remains in the second release film 32, or a problem such as zipping occurs.

The release layer constituting the first release film in the present invention can be provided on the polyester film by the above-described coating stretching method (in-line coating). The coating stretching method (in-line coating) is not limited to the following, but for example, in sequential biaxial stretching, the first stage of stretching may be completed and the coating treatment may be performed before the second stage of stretching. it can. When a release layer is provided on a polyester film by a coating and stretching method, the film can be applied simultaneously with stretching, and the thickness of the release layer can be reduced according to the stretching ratio. Can be manufactured.

Further, the release layer constituting the release film in the present invention preferably contains a curable silicone resin in order to improve the release property. It may be a type mainly composed of a curable silicone resin, or a modified silicone type by graft polymerization with an organic resin such as a urethane resin, an epoxy resin or an alkyd resin may be used as long as the gist of the present invention is not impaired. Also good.

As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet curable type, an electron beam curable type, and a solventless type can be used. Specific examples include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, X, manufactured by Shin-Etsu Chemical Co., Ltd. -62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A / B, X-62-7052, X-62-7028A / B, X-62-7619, X-62-7213, YSR-3022, TPR-6700, TPR-6720, TPR-6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, manufactured by Momentive Performance Materials XS56-A2982, UV9430, TPR6600, TPR66 4, TPR6605, manufactured by Toray Dow Corning Co., Ltd. SRX357, SRX211, SD7220, SD7292, LTC750A, LTC760A, LTC303E, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-204 DKQ3-205, DKQ3-210, etc. Further, a release control agent may be used in combination to adjust the release property of the release layer.

In the present invention, the curing conditions for forming the release layer on the polyester film are not particularly limited. When the release layer is provided by off-line coating, usually at 120 to 200 ° C. for 3 to 40 seconds, The heat treatment is preferably performed at 100 to 180 ° C. for 3 to 40 seconds as a guide. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. In addition, a conventionally well-known apparatus and energy source can be used as an energy source for hardening by active energy ray irradiation. The coating amount (after drying) of the release layer is usually 0.005 to 1 g / m ² , preferably 0.005 to 0.5 g / m ² , and more preferably 0.01 to 0.5 g from the viewpoint of coating properties. The range is 0.2 g / m ² . When the coating amount (after drying) is less than 0.005 g / m ² , the coating property may be less stable and it may be difficult to obtain a uniform coating film. On the other hand, when the coating is thicker than 1 g / m ² , the coating layer adhesion and curability of the release layer itself may be lowered.

The second release film in the present invention needs to have a variation in orientation angle within the film of 6 degrees / 500 mm or less. If the variation in the orientation angle exceeds 6 degrees / 500 mm, it is not suitable for this application.

In the present invention, conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating and the like can be used as a method for providing a release layer on the polyester film. Regarding the coating method, there is an example described in “Coating Method”, published by Yoji Harasaki, published in 1979.

Regarding the first release film and the second release film in the present invention, an adhesive layer, an antistatic layer, an oligomer precipitation-preventing layer, etc., as long as the gist of the present invention is not impaired on the film surface on which no release layer is provided. A coating layer may be provided.

Further, the polyester film constituting the first release film and the second release film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

In this invention, when manufacturing a release film, after apply | coating a coating layer on a polyester film, after winding up a film, a release layer may be provided on a coating layer further, and it apply | coats on a polyester film. After applying and drying the layer, a release layer may be continuously provided on the coating layer, and any method may be used in the present invention.

In the release film constituting the substrate-less pressure-sensitive adhesive sheet in the present invention, the surface specific resistance (R) value of the release surface is 1 × 10 ¹² from the viewpoint of foreign matter adhesion to the pressure-sensitive adhesive layer surface or prevention of peeling electrification. (Ω) or less is preferable. The R value is preferably 1 × 10 ¹¹ (Ω) or less, more preferably 1 × 10 ¹⁰ (Ω) or less. When R is out of the above range, there may be a problem such as entrainment of foreign matters when the release film is peeled off.

Furthermore, in the release film in the present invention, the amount of oligomer (OL) extracted from the surface of the release layer after heat treatment (180 ° C., 10 minutes) is preferably 0.5 mg / m ² or less. When the OL exceeds 0.5 mg / m ² , when the release surface of the release film is bonded to the pressure-sensitive adhesive layer, oligomers precipitate over time, causing trouble during inspection in the inspection process involving optical evaluation. It may become like this.

Next, the pressure-sensitive adhesive layer constituting the substrate-less double-sided pressure-sensitive adhesive sheet according to the present invention will be described below. The pressure-sensitive adhesive layer in the present invention means a layer composed of an adhesive material, and conventionally known materials can be used as long as the gist of the present invention is not impaired. As one specific example, the case where an acrylic adhesive is used will be described below.

In the present invention, the acrylic pressure-sensitive adhesive means a pressure-sensitive adhesive layer containing, as a base polymer, an acrylic polymer formed using an acrylic monomer as an essential monomer component. The acrylic polymer has (meth) acrylic acid alkyl ester and / or (meth) acrylic acid alkoxyalkyl ester having a linear or branched alkyl group as an essential monomer component (more preferably as a main monomer component). ) It is preferably an acrylic polymer to be formed. Furthermore, the acrylic polymer is preferably an acrylic polymer formed using (meth) acrylic acid alkyl ester and acrylic acid alkoxyalkyl ester having a linear or branched alkyl group as essential monomer components.

The pressure-sensitive adhesive layer of the present invention is an acrylic pressure-sensitive adhesive layer formed using (meth) acrylic acid alkyl ester and acrylic acid alkoxyalkyl ester having a linear or branched alkyl group as essential monomer components. preferable.

In addition, the monomer component forming the acrylic polymer that is the base polymer in the pressure-sensitive adhesive layer of the present invention further contains a polar group-containing monomer, a polyfunctional monomer, and other copolymerizable monomers. It may be contained as a polymerization monomer component. In addition, said "(meth) acryl" represents "acryl" and / or "methacryl", and others are the same. Although not particularly limited, the content of the acrylic polymer as the base polymer in the pressure-sensitive adhesive layer of the present invention is preferably 60% by weight or more based on the total weight (100% by weight) of the pressure-sensitive adhesive layer. Preferably it is 80 weight% or more.

As a monomer component for forming the acrylic polymer, a (meth) acrylic acid alkyl ester having a linear or branched alkyl group (hereinafter sometimes simply referred to as “(meth) acrylic acid alkyl ester”) is used. It can be used suitably. Specific examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth ) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate , Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylic acid Isodecyl, undecyl (meth) acrylate, dodecyl (meth) acrylate, (Meth) acrylic acid tridecyl, (meth) acrylic acid tetradecyl, (meth) acrylic acid pentadecyl, (meth) acrylic acid hexadecyl, (meth) acrylic acid heptadecyl, (meth) acrylic acid octadecyl, (meth) acrylic acid nonadecyl, (meta Examples thereof include (meth) acrylic acid alkyl esters having 1 to 20 carbon atoms, such as eicosyl acrylate. Moreover, the (meth) acrylic acid alkyl ester may be used alone or in combination of two or more. Among them, (meth) acrylic acid alkyl esters having 2 to 14 carbon atoms in the alkyl group are preferable, and (meth) acrylic acid alkyl esters having 2 to 10 carbon atoms in the alkyl group are more preferable.

Examples of the polar group-containing monomer include, for example, (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and other carboxyl group-containing monomers or anhydrides thereof (maleic anhydride, etc.) Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, Hydroxyl group (hydroxyl group) -containing monomers such as vinyl alcohol and allyl alcohol; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N -Butoxymethyl (meth) acrylamide, N-hydroxy Amide group-containing monomers such as ethylacrylamide; Amino group-containing monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; Glycidyl group-containing monomers such as glycidyl acrylate and methyl glycidyl (meth) acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinyl-2-pyrrolidone, (meth) acryloylmorpholine, Heterocycle-containing vinyl monomers such as N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine, N-vinyl piperazine, N-vinyl pyrrole, N-vinyl imidazole, N-vinyl oxazole; sodium vinyl sulfonate, etc. Sulfonic acid group-containing monomer; 2-hydroxyethyla Phosphoric acid group-containing monomers such as Leroy Le phosphate; cyclohexyl maleimide, imide group-containing monomers such as isopropyl maleimide; 2-methacryloyloxy such acryloyloxyethyl isocyanate group-containing monomers such as isocyanate. The polar group-containing monomers can be used alone or in combination of two or more.

Examples of the polyfunctional monomer include hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, Neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methanetri (meth) Examples include acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate. The said polyfunctional monomer can also be used individually or in combination of 2 or more types.

The content of the polyfunctional monomer is preferably 0.5% by weight or less with respect to 100% by weight of the monomer component forming the acrylic polymer. When the content exceeds 0.5% by weight, for example, the cohesive force of the pressure-sensitive adhesive layer becomes too high, and the stress relaxation property may be lowered.

Examples of copolymerizable monomers (other copolymerizable monomers) other than the polar group-containing monomer and multifunctional monomer include cyclopentyl (meth) acrylate and cyclohexyl (meth) acrylate. (Meth) acrylic acid ester having an alicyclic hydrocarbon group such as isobornyl (meth) acrylate, and (meth) acrylic acid ester having an aromatic hydrocarbon group such as phenyl (meth) acrylate. (Meth) acrylic acid esters other than alkyl acrylates, alkoxyalkyl (meth) acrylates, polar group-containing monomers and polyfunctional monomers; vinyl esters such as vinyl acetate and vinyl propionate; styrene, Aromatic vinyl compounds such as vinyl toluene; ethylene, butadiene, isoprene, isobutylene, etc. Olefins or dienes; vinyl ethers such as vinyl alkyl ethers; and vinyl chloride.

The acrylic polymer can be prepared by polymerizing the above monomer components by a conventionally known or conventional polymerization method. Examples of the polymerization method of the acrylic polymer include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method by active energy ray irradiation (active energy ray polymerization method). Among these, the solution polymerization method and the active energy ray polymerization method are preferable in terms of transparency, water resistance, production cost and the like.

Examples of the active energy rays irradiated in the above active energy ray polymerization (photopolymerization) include ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron rays, and ultraviolet rays, among others. Ultraviolet rays are suitable for the use of the present invention. Further, the irradiation energy, irradiation time, irradiation method, and the like of the active energy ray are not particularly limited as long as they do not impair the gist of the present invention.

In the solution polymerization, various common solvents can be used. Examples of such solvents include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane Organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. A solvent can be used individually or in combination of 2 or more types.

In preparing the acrylic polymer, a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator) can be used depending on the type of polymerization reaction. A polymerization initiator can also be used individually or in combination of 2 or more types.

The photopolymerization initiator is not particularly limited, but is a benzoin ether photopolymerization initiator, an acetophenone photopolymerization initiator, an α-ketol photopolymerization initiator, an aromatic sulfonyl chloride photopolymerization initiator, Photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, thioxanthone photopolymerization initiators, and the like can be used. The amount of the photopolymerization initiator is not particularly limited as long as it does not impair the gist of the present invention. For example, the amount of the photopolymerization initiator is 0. A range of 01 to 0.2 parts by weight is preferred.

Specific examples of the benzoin ether photopolymerization initiator include, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one And anisole methyl ether. Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4- (t-butyl). Examples include dichloroacetophenone. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one, and the like. . Specific examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Specific examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Specific examples of the ketal photopolymerization initiator include benzyldimethyl ketal. Specific examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone and the like.

Specific examples of the thermal polymerization initiator include azo polymerization initiators [for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis. (2-methylpropionic acid) dimethyl, 4,4′-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [ 2- (5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-di) Methyleneisobutylamidine) dihydrochloride], peroxide polymerization initiators (eg, dibenzoyl peroxide, tert-butylpermaleate, etc.), red Box-type polymerization initiators and the like. The amount of the thermal polymerization initiator used is not particularly limited as long as it does not impair the gist of the present invention.

In the acrylic pressure-sensitive adhesive layer used as one form of the pressure-sensitive adhesive layer in the present invention, a cross-linking agent, a cross-linking accelerator, a tackifier (for example, rosin derivative resin, polyterpene resin, petroleum resin, oil-soluble, if necessary) Phenol resins, etc.), anti-aging agents, fillers, colorants (pigments and dyes, etc.), UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, etc. An additive can be used in the range which does not impair the characteristic of this invention. Moreover, when forming an adhesive layer, various general solvents can also be used. The type of the solvent is not particularly limited, and those exemplified as the solvent used in the above solution polymerization can be used.

The crosslinking agent can control the gel fraction of the pressure-sensitive adhesive layer by crosslinking the base polymer of the pressure-sensitive adhesive layer. As crosslinking agents, isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents Agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, amine crosslinking agents, and the like, and isocyanate crosslinking agents and epoxy crosslinking agents can be preferably used. A crosslinking agent can also be used individually or in combination of 2 or more types.

Next, in the base material-less double-sided pressure-sensitive adhesive sheet of the present invention, when an acrylic pressure-sensitive adhesive composition is used at the time of forming the pressure-sensitive adhesive layer, for example, an optical member (for example, a surface protective layer, a touch panel, and By replacing the air gap between the display surfaces of the image display unit) with a transparent adhesive sheet having a refractive index close to that of the optical member as compared with air, the light transmission is improved, and the brightness of the image display device In consideration of suppressing the decrease in contrast, the pressure-sensitive adhesive layer itself is preferably designed flexibly. For example, the storage elastic modulus (G ′) in dynamic viscoelasticity is preferably 1.0 × 10 ⁵ Pa or less, and more preferably 5.0 × 10 ⁴ Pa or less. When the storage elastic modulus (G ′) exceeds 1.0 × 10 ⁵ Pa, for example, when a gap existing between optical members is filled, the filled adhesive layer does not reach every corner, and peels off at the end, Or there may be a problem such as floating.

The thickness of the pressure-sensitive adhesive layer constituting the substrate-less double-sided pressure-sensitive adhesive sheet in the present invention is in the range of 25 μm to 200 μm, preferably 50 μm to 150 μm. When the pressure-sensitive adhesive layer has a thickness of 25 μm or less, for example, the gap generated between the optical members becomes too large, and it may be difficult to fill the corners with the pressure-sensitive adhesive layer. On the other hand, when the thickness of the pressure-sensitive adhesive layer exceeds 200 μm, the pressure-sensitive adhesive layer thickness becomes excessively thicker than the gap generated between the optical members, and the excess pressure-sensitive adhesive layer components protrude from between the optical members. May occur.

<Second invention>
The present invention is different from the first invention only in that the film haze of the first release film is 6% or more as a constituent requirement from the viewpoint of facilitating identification from the outside. The film haze of the first release film is preferably 10% or more. When the film haze is less than 6%, the release film may be mistaken when the release film is peeled from the substrate-less double-sided pressure-sensitive adhesive sheet.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. The measuring method used in the present invention is as follows.

(1) Measurement of intrinsic viscosity of polyester:
1 g of polyester from which other polymer components and pigments incompatible with polyester were removed was precisely weighed, 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) was added and dissolved, and measurement was performed at 30 ° C.

(2) Measurement of average particle diameter (d ₅₀ : μm):
The value of 50% of integration (weight basis) in the equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution measuring apparatus (SA-CP3 type manufactured by Shimadzu Corporation) was defined as the average particle diameter.

(3) Film haze measurement of the first release film:
In accordance with JIS-K6714, film haze (turbidity) was measured with a ball turbidimeter NDH-20D manufactured by Nippon Denshoku Industries Co., Ltd.

(4) Measurement of main orientation axis and variation of orientation angle in film:
Samples are cut out from the center position toward the both ends from the center position to the both ends in the width direction of the polyester film constituting the second release film and from both ends, and each using a polarization microscope manufactured by Carl Zeiss. Then, the orientation of the polyester film was observed to determine how many times the direction of the main orientation axis in the plane of the polyester film was inclined with respect to the MD of the polyester film. For measurement, when the main orientation axis exceeded 90 degrees, the complementary angle was defined as the angle of the main orientation axis with respect to the MD direction. Further, when calculating the change in the orientation angle including the positions at the extreme ends, if the distance between the sample positions is less than 500 mm, the change in the orientation angle every 500 mm is calculated by proportional calculation. In this way, the variation in the orientation angle every 500 mm in the width direction was determined, and the average value was taken as the orientation angle variation in the width direction of the film.
(Criteria)
A: The variation of the orientation angle is 6 degrees / 500 mm or less.
B: Variation in orientation angle exceeds 6 degrees / 500 mm.

(5) Measurement of in-plane retardation in the second release film:
An in-plane retardation at a center position with respect to the film width direction was measured using a cell gap inspection apparatus RETS-1100A manufactured by Otsuka Electronics Co., Ltd. The in-plane retardation of the film was measured at 23 ° C. using an optical interference method with an aperture diameter of 5 mm.

(6) Release force (F1 / F2) measurement of release film:
After applying one side of double-sided adhesive tape (“No. 502” manufactured by Nitto Denko) to the surface of the release layer of the sample film, cut it to a size of 50 mm × 300 mm and measure the peel force after standing at room temperature for 1 hour To do. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under a tensile speed of 300 mm / min.

(7) Measurement of surface resistivity (R) of release film:
In the sample film, the surface specific resistance (R) of the release surface was measured and judged according to the following criteria. The measurement conditions were 23 ° C. and 50% RH atmosphere. Yokogawa Hewlett-Packard's inner electrode 50mm diameter, outer electrode 70mm diameter concentric circular electrode 16008A (trade name) was placed on the sample in an atmosphere of 23 ° C, 50% RH, and a voltage of 100V was applied, The surface resistivity of the sample was measured with 4329A (trade name), a company's high resistance meter.
(Criteria)
A: R (Ω) is 10 ¹² or less (practical level).
B: R (Ω) exceeds 10 ¹² (practical level).

(8) Measurement of oligomer amount (OL) extracted from release layer surface of release film:
An unheat-treated release film is heated in air at 180 ° C. for 10 minutes in advance. After that, the heat-treated film is brought into close contact with the inner surface of a box having a top and width of 10 cm and a height of 3 cm, and the box shape is obtained. When the coating layer is provided, the coating layer surface is set to the inside. Next, 4 ml of DMF (dimethylformamide) is placed in the box prepared by the above method and left for 3 minutes, and then DMF is recovered. The recovered DMF was supplied to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A) to determine the amount of oligomer in DMF, and this value was divided by the area of the film in contact with DMF to determine the amount of oligomer on the film surface (mg / M ² ).

The amount of oligomer in DMF was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method). The standard sample was prepared by accurately weighing an oligomer (cyclic trimer) collected in advance and dissolving it in accurately measured DMF. The concentration of the standard sample is preferably in the range of 0.001 to 0.01 mg / ml.

The conditions for the liquid chromatograph were as follows.
Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

(9) Measurement of metal element amount from the release surface side of the release film:
The following Table 1 was prepared by the FP (Fundamental Parameter Method) method using a fluorescent X-ray measurement apparatus (model “XRF-1500” manufactured by Shimadzu Corporation) from the surface provided with the release layer of the sample sample in advance. The amount of metal element was measured under the measurement conditions shown in FIG.

(10) Evaluation for promoting adhesion of coated film of release film (practical property substitution evaluation):
The sample film was left in a constant temperature and humidity chamber at 60 ° C. and 80% RH for 4 weeks, and then the sample film was taken out. Thereafter, the release surface of the sample film was rubbed with a tentacle five times, and the degree of release of the release layer was determined according to the following criteria.
(Criteria)
A: The coating film does not fall off (practical level).
B: The coating film turns white but does not fall off (practical level).
C: Detachment of the coating film was confirmed (practically difficult level).

(11) Measurement of storage elastic modulus (G ′) of adhesive layer:
The separator was peeled from the double-sided pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and only the acrylic pressure-sensitive adhesive layer was laminated, and the acrylic pressure-sensitive adhesive layer having a thickness (after drying) of 1.5 mm ± 0.1 mm A laminate was prepared and used as a measurement sample. The above measurement sample was measured at a temperature rising rate of 5 ° C./min in the range of −70 to 200 ° C. under the condition of a frequency of 1 Hz using “Advanced Rheometric Expansion System (ARES)” manufactured by Rheometric Scientific. The storage elastic modulus (G ') at ° C was determined. The storage elastic modulus (G ′) of the pressure-sensitive adhesive layer used in Examples and Comparative Examples in the present invention was 5.0 × 10 ⁴ Pa.

(12) Zipping property evaluation (practical property substitution evaluation):
The following pressure-sensitive adhesive composition was applied to the second release film, heat-treated at 100 ° C. for 5 minutes, and then a pressure-sensitive adhesive layer having a thickness (after drying) of 50 μm was obtained. Next, in the base material-less double-sided pressure-sensitive adhesive sheet in which the first release film is bonded to the surface of the pressure-sensitive adhesive layer, the peeling state is observed when the first release film is peeled off, and the occurrence of zipping is determined according to the following criteria. It was.
<Acrylic adhesive composition>
(Monomer composition)
2-ethylhexyl acrylate 70% by weight
2-methoxyethyl acrylate 29% by weight
4-hydroxybutyl acrylate 1% by weight
0.1 part of Nippon Polyurethane Coronate L was added to 100 parts by weight of the monomer composition to obtain an acrylic pressure-sensitive adhesive layer forming composition.
(Criteria)
A: It peels very smoothly, there is no peeling stripe, and no peeling noise is generated.
B: Minor peeling streaks are observed, peeling noise is slightly generated, or slight zipping occurs (a level that may cause a problem in practical use).
C: Peeling streaks are observed and peeling sound is generated. Zipping occurs (a level that is problematic in practice).

(13) Peelability evaluation of first and second release films (practical property substitution evaluation):
In the item (7), sensory evaluation was performed according to the following criteria for the situation of the interface between the second release layer and the pressure-sensitive adhesive layer when the first release film was peeled off.
(Criteria)
A: No abnormality is observed at the interface between the second release layer and the pressure-sensitive adhesive layer (a level that causes no problem in practical use).
B: Slight floating is observed at the interface between the second release layer and the pressure-sensitive adhesive layer (a level that may cause a practical problem).
C: Clear floating is observed at the interface between the second release layer and the pressure-sensitive adhesive layer (practically problematic level).

(14) Evaluation of testability (practical property substitution evaluation):
Using each base material-less double-sided pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples, after peeling the first release film, the exposed pressure-sensitive adhesive layer surface was bonded to the polarizing plate, and the polarizing plate / pressure-sensitive adhesive layer / The laminated body which consists of a structure of a 2nd mold release film was obtained.
Next, using the obtained laminate, the polarizing plate was inspected by a crossed Nicols method.
Each substrate-less double-sided pressure-sensitive adhesive sheet obtained in the examples was easy to inspect, but among the base-material-less double-sided pressure-sensitive adhesive sheets obtained in the comparative examples, the variation in the orientation angle was 6 degrees / 500 mm. Exceeding cases were difficult to be inspected because the light and darkness became unclear during crossed Nicols.
(Criteria)
A: The variation of the orientation angle is 6 degrees / 500 mm or less.
B: Variation in orientation angle exceeds 6 degrees / 500 mm.

(15) Oligomer sealing evaluation (practical property substitution evaluation):
From the oligomer amount obtained in the item (8), the determination was made according to the following determination criteria.
(Criteria)
A: The amount of oligomer is 0.5 mg / m ² or less.
B: The amount of oligomer exceeds 0.5 mg / m ² .

(16) Discrimination evaluation (practical property substitution evaluation)
The substrate-less double-sided pressure-sensitive adhesive sheet was visually observed, and the side on which the release film having a light peeling force was bonded was determined according to the following criteria.
(Criteria)
A: Identification is possible.
B: Difficult to identify.

(17) Antistatic property evaluation (practical property substitution evaluation)
After sufficiently adjusting the humidity of the double-sided pressure-sensitive adhesive sheet in a measurement atmosphere of 23 ° C. and 50% RH, the first release film is peeled off. Thereafter, the exposed pressure-sensitive adhesive layer surface was brought close to the finely crushed cigarette ash in advance, and the ash adhesion at that time was determined according to the following criteria.
(Criteria)
A: Even if the film is brought into contact with ash, it does not adhere.
B: A large amount adheres only by bringing the film close to ash.

(18) Comprehensive evaluation (practical property substitution evaluation):
Using the base material-less double-sided pressure-sensitive adhesive sheets produced in Examples and Comparative Examples, the following criteria for each evaluation item of zipping occurrence status, peelability, antistatic properties, oligomer sealing properties, adhesion, and testability A comprehensive evaluation was performed.
(Criteria)
A: All occurrences of zipping occurrence, peelability, antistatic property, oligomer sealing property, adhesion, and testability are “A” (a level that causes no problem in practical use).
B: At least one of the zipping occurrence status, peelability, antistatic property, oligomer sealing property, adhesion, and testability is “B” (a level that may cause a problem in practice).
C: “C” is at least one of the occurrence of zipping, peelability, antistatic property, oligomer sealing property, adhesion, and testability (practically problematic level).

<First invention>
The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
Production Example 1 (Polyethylene terephthalate A1)
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, after adding 0.04 part of ethylene glycol slurry ethyl acid phosphate and 0.03 part of antimony trioxide, the temperature reached 280 ° C. and the pressure reached 15 mmHg in 100 minutes. It was 0.3 mmHg. After 4 hours, the system was returned to atmospheric pressure to obtain polyethylene terephthalate A1 having an intrinsic viscosity of 0.61.

Production Example 2 (Polyethylene terephthalate A2)
In Production Example 1, production was carried out in the same manner as in Production Example 1 except that 0.6 part of silica particles having an average particle diameter of 2.5 μm was added to obtain polyethylene terephthalate A2 having an intrinsic viscosity of 0.62.

Production Example 3 (Polyester film F1a)
A raw material blended with polyethylene terephthalate A1 and A2 at a ratio of 80% and 20%, respectively, is used as a raw material for the surface layer, and a raw material of polyethylene terephthalate A1 = 100% is supplied as a raw material for the intermediate layer to two vented extruders. After feeding to an extruder with melt and extruding at 290 ° C., an amorphous film having a thickness of about 1300 μm was obtained by cooling and solidifying on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method. .
This film was stretched 3.5 times in the longitudinal direction at 90 ° C., stretched 4.1 times in the transverse direction at 130 ° C., heat treated at 230 ° C., and then subjected to a relaxation treatment of 4.3% in the width direction. A polyester film F1a having a thickness of 50 μm (thickness ratio = 2.5 μm / 45 μm / 2.5 μm) was obtained.

Production Example 4 (Polyester film F2a)
The raw materials blended with polyethylene terephthalate A1 and A2 at a ratio of 80% and 20%, respectively, are used as the surface layer raw material, and the raw material of polyethylene terephthalate A1 = 100% is supplied to the two vented extruders as the intermediate layer raw material. After melt extrusion at 0 ° C., an amorphous film having a thickness of about 740 μm was obtained by cooling and solidifying on a cooling roll whose surface temperature was set to 40 ° C. using an electrostatic application adhesion method.
This film was stretched 3.5 times in the longitudinal direction at 90 ° C., stretched 4.1 times in the transverse direction at 130 ° C., heat treated at 230 ° C., and then subjected to a relaxation treatment of 4.3% in the width direction. A polyester film having a thickness of 50 μm (thickness ratio = 2.5 μm / 45 μm / 2.5 μm) was obtained. Next, after applying the coating layer composed of the following coating composition off-line by a reverse gravure coating method so that the coating amount (after drying) is 0.05 g / m ² , heat treatment is performed at 120 ° C. for 30 seconds. Thus, a polyester film F2a having a thickness of 50 μm provided with a coating layer was obtained.

(Coating layer composition)
AC1: Colcoat N-103X (manufactured by Colcoat)
AC2: Aluminum tris (acetylacetonate)
AC3: Zirconium tetraacetylacetonate AC4: Titanium tetraacetylacetonate (mixing conditions)
AC1: 99.5% by weight
AC2: 0.5% by weight
AC3: 0% by weight
AC4: 0% by weight

Production Example 5 (Polyester film F3a)
A polyester film F3a was obtained in the same manner as in Production Example 4 except that the composition of the coating layer in Production Example 4 was different.

Production Example 6 (Polyester film F4a)
Manufactured in the same manner as in Manufacture Example 4 except that the composition of the coating layer was different in Manufacture Example 4, and a polyester film F4a was obtained.

Production Example 7 (Polyester film F5a)
A polyester film F5a was obtained in the same manner as in Production Example 4 except that the composition of the coating layer in Production Example 4 was different.

Production Example 8 (Polyester film F6a)
The raw materials blended with polyethylene terephthalate A1 and A2 at a ratio of 80% and 20%, respectively, are used as the surface layer raw material, and the raw material of polyethylene terephthalate A1 = 100% is supplied to the two vented extruders as the intermediate layer raw material. After melt extrusion at 0 ° C., an amorphous film having a thickness of about 740 μm was obtained by cooling and solidifying on a cooling roll whose surface temperature was set to 40 ° C. using an electrostatic application adhesion method.
The film was stretched 2.8 times in the machine direction at 90 ° C., 5.4 times in the transverse direction at 120 ° C., heat treated at 200 ° C., and then subjected to a relaxation treatment of 4.3% in the width direction. A polyester film having a thickness of 50 μm (thickness ratio = 2.5 μm / 45 μm / 2.5 μm) was obtained. Next, after applying the coating layer composed of the following coating composition off-line by a reverse gravure coating method so that the coating amount (after drying) is 0.05 g / m ² , heat treatment is performed at 120 ° C. for 30 seconds. Thus, a 50 μm-thick polyester film F6a provided with a coating layer was obtained.

Production Example 9 (Polyester film F7a)
Manufactured in the same manner as in Manufacture Example 4 except that no coating layer was provided in Manufacture Example 4 to obtain a polyester film F7a.

(Release layer composition-A)
Curing type silicone resin (LTC303E: manufactured by Toray Dow Corning) 100 parts Curing agent (SRX212: manufactured by Toray Dow Corning) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

(Release layer composition-B)
Curing type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical) 100 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

(Release layer composition-C)
Curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical Co., Ltd.) 95 parts Heavy release control agent (BY24-4980: manufactured by Toray Dow Corning)
10 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

(Releasing layer composition -D)
Curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical Co., Ltd.) 95 parts Heavy release control agent (BY24-4980: manufactured by Toray Dow Corning)
1 part Curing agent (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

Example 1:
<Manufacture of first release film>
The following release layer composition-A was applied to the polyester film F1a by a reverse gravure coating method so that the coating amount (after drying) was 0.1 g / m ^2, and then heat treated at 120 ° C. for 30 seconds.

From the above, the characteristics of the obtained first release film are shown in Tables 2 to 4. In addition, the Example number in Table 4 means the Example number in Table 5 mentioned later (hereinafter the same).

<Manufacture of second release film>
In the polyester film F2a, after applying the release layer composition -D below on the coating layer offline by a reverse gravure coating method so that the coating amount becomes 0.1 g / m ² (after drying), Heat treated for 30 seconds. The characteristics of the obtained second release film are shown in Tables 1 to 4.
(Release layer composition-C)
Curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical Co., Ltd.) 95 parts Heavy release control agent (BY24-4980: manufactured by Toray Dow Corning)
10 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

<Manufacture of substrate-less double-sided PSA sheet>
On the release layer of the obtained 2nd release film, after coating the coating liquid comprised from the following acrylic adhesive composition with an applicator, using a hot-air circulation furnace, 100 degreeC, 5 It heat-processed for minutes and obtained the adhesive layer whose application amount (after drying) is 50 g / m < ² >.

<Acrylic pressure-sensitive adhesive layer forming composition>
(Monomer composition)
2-ethylhexyl acrylate 70% by weight
2-methoxyethyl acrylate 29% by weight
4-hydroxybutyl acrylate 1% by weight
0.1 part of Nippon Polyurethane Coronate L was added to 100 parts by weight of the monomer composition to obtain an acrylic pressure-sensitive adhesive layer forming composition.
Next, using a 2 kg rubber roller, the release layer and the pressure-sensitive adhesive layer of the first release film were bonded together to obtain a substrate-less double-sided pressure-sensitive adhesive sheet. Table 5 shows the properties of the obtained substrate-less double-sided pressure-sensitive adhesive sheet.

Examples 2 to 6 and Comparative Examples 1 to 3:
In Example 1, the coating agent composition, the release agent composition, and the polyester film base material thickness were produced in the same manner as in Example 1 except that the thicknesses were changed as shown in Tables 2 and 3 below. A mold film and a second release film were obtained. Then, it bonded together through the adhesive layer using both, and obtained the base material-less double-sided adhesive sheet. Tables 2 to 5 show the properties of the release films and the baseless double-sided PSA sheets obtained in the above examples and comparative examples.

<Second invention>
The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
Production Example 10 (polyethylene terephthalate A1)
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, after adding 0.04 part of ethylene glycol slurry ethyl acid phosphate and 0.03 part of antimony trioxide, the temperature reached 280 ° C. and the pressure reached 15 mmHg in 100 minutes. It was 0.3 mmHg. After 4 hours, the system was returned to atmospheric pressure to obtain polyethylene terephthalate A1 having an intrinsic viscosity of 0.61.

Production Example 11 (Polyethylene terephthalate A2)
In Production Example 10, production was carried out in the same manner as in Production Example 1 except that 0.6 part of silica particles having an average particle diameter of 2.5 μm was added to obtain polyethylene terephthalate A2 having an intrinsic viscosity of 0.62.

Production Example 12 (polyethylene terephthalate A3)
In Production Example 1, production was carried out in the same manner as in Production Example 10 except that 1.0 part of synthetic calcium carbonate particles having an average particle diameter of 0.8 μm was added to obtain polyethylene terephthalate A3 having an intrinsic viscosity of 0.62.

Production Example 13 (Polyester film F1b)
Two raw materials were blended with polyethylene terephthalate A1 and A3 in proportions of 92% and 8%, respectively, and raw materials blended with polyethylene terephthalate A1 and A3 in proportions of 80% and 20%, respectively. After being melted and extruded at 290 ° C., it was cooled and solidified on a cooling roll set at a surface temperature of 40 ° C. using an electrostatic application adhesion method. An amorphous film having a thickness of about 1300 μm was obtained.
This film was stretched 3.5 times in the longitudinal direction at 90 ° C., stretched 4.1 times in the transverse direction at 130 ° C., heat treated at 230 ° C., and then subjected to a relaxation treatment of 4.3% in the width direction. A polyester film F1b having a thickness of 50 μm (thickness ratio = 2.5 μm / 45 μm / 2.5 μm) was obtained.

Production Example 14 (Polyester film F2b)
Two raw materials were blended with polyethylene terephthalate A1 and A3 in proportions of 92% and 8%, respectively, and raw materials blended with polyethylene terephthalate A1 and A3 in proportions of 80% and 20%, respectively. After being melt-extruded at 290 ° C. and cooled and solidified on a cooling roll set at a surface temperature of 40 ° C. using an electrostatic application adhesion method, an amorphous film having a thickness of about 740 μm was obtained. Obtained.
This film was stretched 3.5 times in the longitudinal direction at 90 ° C., stretched 4.1 times in the transverse direction at 130 ° C., heat treated at 230 ° C., and then subjected to a relaxation treatment of 4.3% in the width direction. A polyester film having a thickness of 50 μm (thickness ratio = 2.5 μm / 45 μm / 2.5 μm) was obtained. Next, after applying the coating layer composed of the following coating composition off-line by a reverse gravure coating method so that the coating amount (after drying) is 0.05 g / m ² , heat treatment is performed at 120 ° C. for 30 seconds. Thus, a 50 μm thick polyester film F2b provided with a coating layer was obtained.

Production Example 15 (Polyester film F3b)
A polyester film F3b was obtained in the same manner as in Production Example 14 except that the composition of the coating layer in Production Example 14 was different.

Production Example 16 (Polyester film F4b)
Manufactured in the same manner as in Manufacture Example 14 except that the composition of the coating layer was different in Manufacture Example 14, and a polyester film F4b was obtained.

Production Example 17 (Polyester film F5b)
A polyester film F5b was obtained in the same manner as in Production Example 14 except that the composition of the coating layer in Production Example 14 was different.

Production Example 18 (Polyester film F6b)
Two raw materials were blended with polyethylene terephthalate A1 and A3 in proportions of 92% and 8%, respectively, and raw materials blended with polyethylene terephthalate A1 and A3 in proportions of 80% and 20%, respectively. After being melt-extruded at 290 ° C. and cooled and solidified on a cooling roll set at a surface temperature of 40 ° C. using an electrostatic application adhesion method, an amorphous film having a thickness of about 740 μm was obtained. Obtained. The film was stretched 2.8 times in the machine direction at 90 ° C., 5.4 times in the transverse direction at 120 ° C., heat treated at 200 ° C., and then subjected to a relaxation treatment of 4.3% in the width direction. A polyester film having a thickness of 50 μm (thickness ratio = 2.5 μm / 45 μm / 2.5 μm) was obtained. Next, after applying the coating layer composed of the following coating composition off-line by a reverse gravure coating method so that the coating amount (after drying) is 0.05 g / m ² , heat treatment is performed at 120 ° C. for 30 seconds. Thus, a polyester film F6b having a thickness of 50 μm provided with a coating layer was obtained.

Production Example 19 (Polyester film F7b)
A polyester film F7b was obtained in the same manner as in Production Example 14 except that no coating layer was provided in Production Example 14.

Production Example 20 (Polyester film F8b)
In Production Example 14, the raw material composition of the surface layer and the intermediate layer was different as described below, and production was carried out in the same manner as in Production Example 14 except that no coating layer was provided to obtain a polyester film F8b.
Surface layer raw materials: Raw materials obtained by blending polyethylene terephthalate A1 and A2 at a ratio of 80% and 20%, respectively.
Intermediate layer raw material: Polyethylene terephthalate A1 = 100% raw material was used.

Example 7:
<Manufacture of first release film>
The following release layer composition-A was applied to the polyester film F1b offline by a reverse gravure coating method so that the coating amount (after drying) was 0.1 g / m ² , followed by heat treatment at 120 ° C. for 30 seconds.

From the above, the characteristics of the obtained first release film are shown in Tables 6 to 8. In addition, the Example number in Table 8 means the Example number in Table 9 described later (hereinafter the same).

<Manufacture of second release film>
Polyester film F
In 2b, the following release layer composition-D was applied on the coating layer offline by reverse gravure coating so that the coating amount was 0.1 g / m ² (after drying), and then 120 ° C. for 30 seconds. Heat treated. Tables 6 to 8 show the characteristics of the obtained second release film.
(Release layer composition-C)
Curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical Co., Ltd.) 95 parts Heavy release control agent (BY24-4980: manufactured by Toray Dow Corning)
10 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts

<Manufacture of substrate-less double-sided PSA sheet>
On the release layer of the obtained 2nd release film, after coating the coating liquid comprised from the following acrylic adhesive composition with an applicator, using a hot-air circulation furnace, 100 degreeC, 5 It heat-processed for minutes and obtained the adhesive layer whose application amount (after drying) is 50 micrometers.

<Acrylic pressure-sensitive adhesive layer forming composition>
(Monomer composition)
2-ethylhexyl acrylate 70% by weight
2-methoxyethyl acrylate 29% by weight
4-hydroxybutyl acrylate 1% by weight
0.1 part of Nippon Polyurethane Coronate L was added to 100 parts by weight of the monomer composition to obtain an acrylic pressure-sensitive adhesive layer forming composition.
Next, using a 2 kg rubber roller, the release layer and the pressure-sensitive adhesive layer of the first release film were bonded together to obtain a substrate-less double-sided pressure-sensitive adhesive sheet.

Examples 8 to 12 and Comparative Examples 4 to 7:
In Example 7, the coating agent composition, the release agent composition, and the polyester film substrate thickness were produced in the same manner as in Example 7 except that the thicknesses were changed as shown in Tables 6 and 7 below. A mold film and a second release film were obtained. Then, it bonded together through the adhesive layer using both, and obtained the base material-less double-sided adhesive sheet. Tables 6 to 9 show the characteristics of the release films and the baseless double-sided PSA sheets obtained in the above Examples and Comparative Examples.

The substrate-less double-sided pressure-sensitive adhesive sheet of the present invention has good antistatic properties, releasability, oligomer sealing properties, and good testability, for example, liquid crystal polarizing plate manufacturing, capacitive touch panel manufacturing members, etc. It is suitable as various optical members.

10: Substrate-less double-sided adhesive sheet 11: Adhesive layer 13: First release film substrate 14: First application layer 15: First release agent layer 23: Second release film substrate 24: Second application Layer 25: Second release agent layer 31: First release film (light release sheet)
32: Second release film (heavy release sheet)

Claims

Release films are laminated on both sides of the pressure-sensitive adhesive layer, and the release force of one release film (first release film) is smaller than the release force of the other release film (second release film). 2. A substrate-less double-sided pressure-sensitive adhesive sheet, wherein the second release film simultaneously satisfies the following conditions (a) to (c):
(A) A release film in which a release layer is provided on the surface of a coating layer containing a hydrolyzable silicon compound provided on a biaxially stretched polyester film.
(B) The variation of the orientation angle in the plane of the biaxially stretched polyester film is 6 degrees / 500 mm or less.
(C) The amount of oligomer extracted with dimethylformamide from the surface of the release layer of the release film is 0.5 mg / m 2 or less.
The base material-less double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the film haze of the first release film is 6% or more.
The substrate-less double-sided pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the hydrolyzable silicon compound is a compound represented by the following general formula.
[Chemical 1]
Si (OR 1 ) x (R 2 ) 4-x
(Where x represents an integer of 2 to 4, R 1 represents an alkyl group or an acyl group, and R 2 represents an organic group having 1 to 10 carbon atoms.)
4. The substrate-less double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the coating layer of the second release film contains a metal element-containing organic compound.
The blending ratio (weight ratio) (A) :( B) of the hydrolyzable silicon compound (A) and the metal element-containing organic compound (B) is in the range of 1: 0.001 to 1: 0.01. The base material-less double-sided pressure-sensitive adhesive sheet described in 1.