JP2013001816A - Base-less double-sided tacky adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base-less double-sided tacky adhesive sheet, which is usable, in particular, as a member for an electrostatic capacitance type touch panel and has inspection ease to exhibit excellent mold releasability and to allow inspection with release films kept stuck during an inspection process accompanied by optical evaluation.SOLUTION: In the base-less double-sided tacky adhesive sheet, the release films are layered respectively on both sides of an adhesive layer. In one of the release films, a release layer is arranged on one surface of a biaxially oriented polyester film, a film internal haze is ≤0.8%, and the maximum surface roughness (Rt) of the film surface where no release layer is arranged is ≥300 nm.

Description

  The present invention relates to a substrate-less double-sided pressure-sensitive adhesive sheet, which has good releasability and has inspection ease in an inspection process involving optical evaluation. For example, it is suitable for a capacitive touch panel. The present invention relates to a double-sided pressure-sensitive adhesive sheet.

  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 substrate-less double-sided pressure-sensitive adhesive sheet has attracted attention because of its good workability, and its applications are 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. Since the capacitive touch panel tends to have a thicker printing step than the resistive film method, 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 bubbles are mixed into the part of the pressure-sensitive adhesive layer transferred to the release film. There was a case. Therefore, when using the baseless double-sided pressure-sensitive adhesive sheet for optical applications, not only the baseless double-sided pressure-sensitive adhesive sheet but also the release film to be combined is more severe than before, and release with fewer optical defects such as foreign matter There is a situation where a film is needed.

  On the other hand, in the inspection process accompanied by optical evaluation, when a release film that is generally used is used, there is a case in which a problem such as overlooking of contamination of foreign matter may occur. In particular, when using a soft adhesive layer with a thick adhesive, the foreign matter involved is present in a deeper position in the thickness direction of the adhesive layer due to the flexibility of the adhesive layer itself during the manufacturing process. There is a case. Therefore, in order to confirm the presence or absence of foreign matter, when a normal release film is used, it is necessary to peel off the release film at one end. Therefore, in the inspection process, further improvement in workability is desired. It was.

  As described above, when using a substrate-less double-sided PSA sheet for optical applications, not only the substrate-less double-sided PSA sheet but also the release film to be combined is in a situation where stricter quality is required than before. .

Japanese Patent Application No. 2010-56884 Japanese Patent Application No. 2010-121101 Japanese Patent Application No. 2010-97765 Japanese Patent Application No. 2010-97925

  The present invention has been made in view of the above-described circumstances, and the problem to be solved is that, particularly as a capacitive touch panel member, in an inspection process involving optical evaluation, the releasability is good, and the mold release The present invention provides a substrate-less double-sided pressure-sensitive adhesive sheet that can be inspected even in a state in which the film is bonded, and has so-called ease of inspection.

  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. .

  That is, the gist of the present invention is a baseless double-sided pressure-sensitive adhesive sheet in which release films are laminated on both sides of an adhesive layer, and one release film has a release layer on one side of a biaxially stretched polyester film. In addition, the present invention provides a substrateless double-sided pressure-sensitive adhesive sheet characterized in that the film internal haze is 0.8% or less and the maximum surface roughness (Rt) of the film surface on which no release layer is provided is 300 nm or more. .

  Since the substrate-less double-sided pressure-sensitive adhesive sheet of the present invention has good releasability and has inspection ease in an inspection process involving optical evaluation, for example, a substrate-less double-sided pressure-sensitive adhesive used for a capacitive touch panel It is suitable as a sheet and has high industrial value.

  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 a 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.

  The polyester used for the polyester film in the present invention 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). 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanol, neopentyl glycol, is mentioned. 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 blend 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, during the polyester production process, it is possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed. On the other hand, the shape of the particles to be used is not particularly limited. Either a rod shape or a flat shape may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-3 micrometers normally, Preferably it is the range of 0.01-1 micrometer. 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 of producing the polyester constituting each layer, but preferably a polycondensation reaction may be carried out 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.

  Although the thickness of the polyester film which comprises the 1st and 2nd release film of this invention will not be specifically limited if it is a range which can be formed into a film, Usually, 25-250 micrometers, Preferably it is 38-188 micrometers. More preferably, it is the range of 50-125 micrometers.

  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. Subsequently, the extending | stretching temperature orthogonal to the extending | stretching direction of the 1st step is 70-170 degreeC normally, and a draw ratio is 3.0 to 7 times normally, Preferably it is 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.

  The simultaneous biaxial stretching method can also 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 of temperature control 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, a known stretching method such as a screw method, a pantograph method, a linear drive method, or the like can be employed.

  Furthermore, a so-called coating stretching method (in-line coating) in which the film surface is treated during the above-described polyester film stretching step can be applied. 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.

  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 peel force between the acrylic adhesive tape and the release layer. (F) is usually in the range of 5 to 70 mN / cm, preferably 10 to 60 mN / cm.

  The peel strength of the first release film corresponding to the light release side with respect to the adhesive layer is preferably 3 to 50 mN / cm, more preferably 5 to 25 mN / cm. When the peeling force of the first release film is less than 3 mN / cm, the release film may be easily peeled off in a scene that does not need to be peeled off. In addition, when the peeling force of the first release film exceeds 50 mN / cm, a peeling phenomenon called floating may occur between the second release film and the adhesive layer in the step of peeling the first release film. is there.

  By suppressing the absolute value of the peeling force of the first release film to a low value, even if the absolute value of the peeling force of the second release film is lowered, it is possible to increase the difference in the peeling force between the two release films. . In addition, by setting the peeling force of the first release film 31 to a certain value or more, the first release film is easily peeled from the adhesive layer in a scene that does not need to be peeled before use, or It is possible to prevent the first release film from floating from the adhesive layer.

  On the other hand, the peeling force of the second release film corresponding to the heavy peeling side is preferably 20 to 100 mN / cm, and more preferably 30 to 60 mN / cm. If the peeling force of the second release film is less than 20 mN / cm, when the first release film is peeled off, there may be a problem that a part of the second release film peels 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 peel force of the second release film is usually 2.0 times or more, preferably 3.0 times or more of the peel force of the first release film. When the peel force of the second release film is less than 2.0 times the peel force of the first release film, the second release film floats from the pressure-sensitive adhesive layer when the first release film on the light release side is peeled off. In some cases, the phenomenon occurs, the adhesive layer component remains in the second release film, 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 (inline 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.

  Moreover, it is preferable that the release layer which comprises the release film in this invention contains a curable silicone resin in order to make mold release property favorable. 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, 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-6720, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605, manufactured by Momentive Performance Materials Toray Dawkonin Examples include SRX357, SRX211, SD7220, SD7292, LTC750A, LTC760A, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-203, DKQ3-205, DKQ3-210, etc. Is done. 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, and when providing the release layer 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, as an energy source for hardening by active energy ray irradiation, a well-known apparatus and an energy source can be used. The coating amount (after drying) of the release layer is usually from 0.005 to 1 g / m ² , preferably from 0.005 to 0.5 g / m ² , more preferably from 0.01 to 5 in terms of coatability. 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.

  In the present invention, it is necessary to bond release films on both sides of the baseless double-sided pressure-sensitive adhesive sheet, and the thickness of the second release film is the thickness of the first release film with respect to the thickness ratio of each release film. 2 times or more, preferably 3 times or more. For example, by reducing the film thickness of the first release film on the light release side, it becomes possible to prevent the floating that occurs at the interface between the second release film and the adhesive layer when the first release film is peeled off. Have advantages.

  In addition, when the adhesive layer is applied on the release surface of the second release film, in order to eliminate the influence of foreign matter and unevenness in the process, the influence of unevenness and foreign matter is more It is preferable to further increase the film thickness of the second release film that is easily received.

  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 a description example in “Coating method” published by Yasuharu Harasaki in 1979.

  Regarding the first and second release films in the present invention, coating layers such as an adhesive layer, an antistatic layer, and an oligomer precipitation preventing layer are provided on the surface where no release layer is provided, as long as the gist of the present invention is not impaired. It may be provided.

  Moreover, you may give surface treatments, such as a corona treatment and a plasma treatment, to the polyester film which comprises a 1st and 2nd mold release film previously.

The film internal haze of the first release film thus obtained needs to be 0.8% or less, preferably 0.6% or less, in order to ensure the ease of inspection in the inspection process involving optical evaluation. is there. When the range exceeds 0.8%, from the obtained first release film side, when an inspection with optical evaluation is performed, the first release film must be peeled off at the time of the inspection. Cause a malfunction.
In the present invention, for the first release film, as a specific method for keeping the film internal haze within a predetermined range, for example, in the polyester film constituting the first release film, a laminated polyester film is used. In this case, the particle content of the intermediate layer is suppressed to substantially 0%, and the particle content of the surface layer is increased as much as possible while the polyester layer thickness of the surface layer is made as thin as possible. It is preferable at the point from which the 1st mold release film which has property is obtained.

  In order to satisfy the above range, when the laminated polyester film constituting the first release film is used, the polyester layer thickness of the outermost layer is 4.0 μm or less on one side, preferably 2.0 μm or less. When the polyester layer thickness is out of the above range, the content of particles in the laminated polyester film is excessively increased and the film internal haze may exceed 0.8%.

  Furthermore, in the first release film of the present invention, the maximum roughness (Rt) of the film surface on which the release layer is not provided needs to be 300 nm or more in order to ensure the ease of inspection of the substrate-less pressure-sensitive adhesive sheet. Preferably, it is 400 nm or more. When Rt is less than 300 nm, problems such as blocking when the first release film is wound during handling are caused.

Next, the pressure-sensitive adhesive layer constituting the substrate-less double-sided pressure-sensitive adhesive sheet in the present invention will be described below. The adhesive layer in the present invention means a layer composed of a material having adhesiveness, 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 preferably 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. .

In addition, the monomer component forming the acrylic polymer that is the base polymer in the adhesive layer of the present invention is further copolymerized with a polar group-containing monomer, a polyfunctional monomer, and other copolymerizable monomers. It may be contained as a 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 ) (Meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group 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 ester having 2 to 14 carbon atoms in the alkyl group is preferable, and (meth) acrylic acid alkyl ester having 2 to 10 carbon atoms in the alkyl group is 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 (such as maleic anhydride) Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 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 ethyl acrylamide; Amino group-containing monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; (meth) 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, tetramethylolmethane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, Examples thereof include 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 vinyltoluene; ethylene, butadiene, isoprene, isobutylene, etc. Fins 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.

  With respect to the photopolymerization initiator, it is not particularly limited, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, 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 used 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 0.1% relative to 100 parts by weight of the total amount of monomer components forming the acrylic polymer. 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 and 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one. . 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-based polymerization initiators (eg, dibenzoyl peroxide, tert-butylpermaleate, etc.), redox Scan 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 embodiment of the pressure-sensitive adhesive layer in the present invention, a crosslinking agent, a crosslinking accelerator, a tackifier (for example, rosin derivative resin, polyterpene resin, petroleum resin, oil-soluble phenol) Resin, etc.), anti-aging agents, fillers, colorants (pigments, dyes, etc.), UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, etc. An agent 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 said crosslinking agent can control the gel fraction of an adhesive layer by bridge | crosslinking the base polymer of an 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 laminate of the present invention, when an acrylic pressure-sensitive adhesive composition is used at the time of forming the pressure-sensitive adhesive layer, which is a structural unit, for example, an optical member (for example, a surface protective layer, a touch panel, And the display surface of the image display unit) is replaced with a transparent adhesive sheet having a refractive index close to that of an optical member compared to air, thereby improving light transmission and brightness of the image display device. In view of suppressing the decrease in contrast and 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 sheet constituting the substrate-less double-sided pressure-sensitive adhesive sheet in the present invention is in the range of 50 μm to 400 μm, preferably 100 μm to 400 μm, and more preferably 150 μm to 350 μm. In the case of 50 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 adhesive sheet. On the other hand, when the thickness of the pressure-sensitive adhesive sheet exceeds 400 μm, the thickness of the pressure-sensitive adhesive sheet becomes excessively thicker than the gap generated between the optical members, and there arises a problem such that the excess pressure-sensitive adhesive sheet component protrudes between the optical members. There is a case.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. 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 have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. It was dissolved and measured at 30 ° C.

(2) Measurement of average particle diameter (d ₅₀ : μm) Integration (weight basis) 50% in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) Was the average particle size.

(3) Film internal haze measurement of first release film Filled with ethanol solution using haze meter device (model: HZ-2) manufactured by Suga Test Co., Ltd. based on JIS-K-7136 using sample film The haze value of the obtained glass cell was set to 0%, and the internal haze of the film was measured in a state where the test piece of the sample film was immersed in the cell.

(4) Maximum roughness (Rt) measurement of film surface not provided with release layer Non-contact surface measurement system using direct phase detection interferometry (so-called two-beam interferometry using Michelson interference) The maximum roughness (Rt) of the film surface on which the release layer of the sample film was not provided was measured by “Micromap 512” manufactured by Micromap. The measurement wavelength was 554 nm, an objective lens with a magnification of 20 times was used, 20 visual fields were measured, and the average value was adopted.

(5) Measurement of storage elastic modulus (G ′) of adhesive layer The separator was peeled from the double-sided adhesive sheets obtained in Examples and Comparative Examples, and only the acrylic adhesive layer was laminated, and the thickness (after drying) A laminate of 1.5 mm ± 0.1 mm acrylic pressure-sensitive adhesive layer 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 an “Advanced Rheometric Expansion System (ARES)” manufactured by Rheometric Scientific. The storage elastic modulus (G ') at ° C was determined. In addition, the storage elastic modulus (G ') of the adhesion layer used by the Example and comparative example in this invention was 5.0 * 10 < ⁴ > Pa.

(6) Release force (F1 and F2) measurement of release film After applying one side of a double-sided adhesive tape (Nitto Denko “No. 502”) to the release layer surface of the sample film, the size is 50 mm × 300 mm. Cut and measure the peel force after standing at room temperature for 1 hour. 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) Zipping occurrence status (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 150 μm was obtained. Next, in the substrate-less double-sided pressure-sensitive adhesive sheet in which the first release film was bonded to the surface of the adhesive layer, the peeling state was observed when the first release film was peeled off, and the occurrence of zipping was determined according to the following criteria. .
<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)
○: Peeling very smoothly, no peeling streaks, no peeling noise △: Minor peeling streaks are observed, slight peeling noise is generated, or slight zipping occurs (problem is practically problematic) May have a level)
X: Peeling streaks are observed, peeling noise is generated, or zipping occurs (a level that causes a problem in practical use)

(8) Evaluation of peelability 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 adhesive layer when the first release film was peeled off.

(Criteria)
○: No abnormality is observed at the interface between the second release layer and the adhesive layer (practically no problem level)
Δ: Slight floating is observed at the interface between the second release layer and the adhesive layer (a level that may cause a practical problem)
X: Clear floating is observed at the interface between the second release layer and the adhesive layer (practically problematic level)

(9) Inspectability evaluation (practical property substitution evaluation)
The first release film side of the substrate-less double-sided adhesive sheet with release films on both sides of the adhesive layer is surface-observed with a digital microscope manufactured by HIROX, and the ease of inspection is determined according to the following criteria. It was.
(Criteria)
○: Easy inspection (practical level)
×: Since it is difficult to inspect, it is necessary to peel off the release film at one end (practically problematic level)

(10) Comprehensive evaluation (practical property substitution evaluation)
Using the substrate-less double-sided pressure-sensitive adhesive sheets produced in the examples and comparative examples, comprehensive evaluation was performed according to the following criteria for each evaluation item of zipping occurrence status, peelability, and testability.
(Criteria)
○: All the zipping occurrence status, peelability, and ease of inspection are ○ (no problem level for practical use). Δ: At least one of the zipping occurrence status, peelability, ease of inspection, zipping occurrence status, peelability is Δ. (Practical level that may cause problems)
×: At least one of zipping occurrence status, peelability, and testability is × (practically problematic level)

The polyester used in the examples and comparative examples was prepared as follows.
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 0.3 part of alumina silicate particles having an average particle size of 0.035 μm was added to obtain polyethylene terephthalate A2 having an intrinsic viscosity of 0.61.

Production Example 3 (Polyethylene terephthalate A3)
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 A3 having an intrinsic viscosity of 0.62.

<Manufacture of polyester film F1>
Two vented extruders with polyethylene terephthalate A1, A2 and A3 blended in proportions of 80%, 0% and 20%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material After being melt-extruded at 290 ° C., it was cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method to obtain an amorphous film having a thickness of about 1500 μm. This film was stretched 3.3 times in the longitudinal direction at 85 ° C., and coating liquid A was applied to a thickness (after drying) of 0.06 μm on one side of the film, and then stretched 3.6 times in the transverse direction at 100 ° C. And a heat treatment at 210 ° C. to obtain a polyester film F1 having a thickness of 125 μm (thickness ratio = 2.5 μm / 120 μm / 2.5 μm).

<Manufacture of polyester film F2>
Two vented extruders with polyethylene terephthalate A1, A2 and A3 blended in proportions of 80%, 0% and 20%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material After being melt-extruded at 290 ° C. and then melted and extruded at 290 ° C., it was cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. by using an electrostatic application adhesion method, so A regular film was obtained. This film was stretched 3.5 times in the machine direction at 85 ° C., and coating solution A was applied to a thickness (after drying) of 0.06 μm on one side of the film, and then stretched 3.8 times in the transverse direction at 100 ° C. The polyester film F2 having a thickness of 100 μm (thickness ratio = 2.5 μm / 95 μm / 2.5 μm) was obtained by heat treatment at 210 ° C.

<Manufacture of polyester film F3>
Two vented extruders with polyethylene terephthalate A1, A2 and A3 blended in proportions of 80%, 0% and 20%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material And melt-extruded at 290 ° C., and then cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method, to obtain an amorphous film having a thickness of about 1100 μm. This film was stretched 3.5 times in the machine direction at 85 ° C., and coating solution A was applied to a thickness (after drying) of 0.06 μm on one side of the film, and then stretched 4.0 times in the transverse direction at 100 ° C. The polyester film F3 having a thickness of 75 μm (thickness ratio = 2.5 μm / 70 μm / 2.5 μm) was obtained by heat treatment at 210 ° C.

<Manufacture of polyester film F4>
Two vented extruders using polyethylene terephthalate A1, A2, and A3 blended in proportions of 89%, 0%, and 11%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material And melt-extruded at 290 ° C., and then cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method, to obtain an amorphous film having a thickness of about 1100 μm. This film was stretched 3.5 times in the machine direction at 85 ° C., and coating solution A was applied to a thickness (after drying) of 0.06 μm on one side of the film, and then stretched 4.0 times in the transverse direction at 100 ° C. The polyester film F4 having a thickness of 75 μm (thickness ratio = 2.5 μm / 70 μm / 2.5 μm) was obtained by heat treatment at 210 ° C.

<Manufacture of polyester film F5>
Two vented extruders with polyethylene terephthalate A1, A2 and A3 blended in proportions of 80%, 0% and 20%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material After being melt-extruded at 290 ° C., it was cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method to obtain an amorphous film having a thickness of about 740 μm. This film was stretched 3.7 times in the machine direction at 85 ° C., and coating solution A was applied to a thickness (after drying) of 0.06 μm on one side of the film, and then stretched 4.0 times in the transverse direction at 100 ° C. The polyester film F5 having a thickness of 50 μm (thickness ratio = 2.5 μm / 45 μm / 2.5 μm) was obtained by heat treatment at 210 ° C.

<Manufacture of polyester film F6>
Two vented extruders using polyethylene terephthalate A1, A2, and A3 blended in proportions of 89%, 0%, and 11%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material After being melt-extruded at 290 ° C., it was cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method to obtain an amorphous film having a thickness of about 740 μm. This film was stretched 3.7 times in the machine direction at 85 ° C., and coating solution A was applied to a thickness (after drying) of 0.06 μm on one side of the film, and then stretched 4.0 times in the transverse direction at 100 ° C. The polyester film F6 having a thickness of 50 μm (thickness ratio = 2.5 μm / 45 μm / 2.5 μm) was obtained by heat treatment at 210 ° C.

<Manufacture of polyester film F7>
Two vented extruders with polyethylene terephthalate A1, A2 and A3 blended in proportions of 80%, 0% and 20%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material And melt-extruded at 290 ° C., and then cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method, to obtain an amorphous film having a thickness of about 550 μm. This film was stretched 3.7 times in the machine direction at 85 ° C., and the coating liquid A was applied to a thickness (after drying) of 0.06 μm on one side of the film, and then stretched 3.9 times in the transverse direction at 100 ° C. And a heat treatment at 210 ° C. to obtain a polyester film F7 having a thickness of 38 μm (thickness ratio = 2.5 μm / 33 μm / 2.5 μm).

<Manufacture of polyester film F8>
Two vented extruders using polyethylene terephthalate A1, A2, and A3 blended in proportions of 89%, 0%, and 11%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material And melt-extruded at 290 ° C., and then cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method, to obtain an amorphous film having a thickness of about 550 μm. This film was stretched 3.7 times in the machine direction at 85 ° C., and coating solution A was applied to one side of the film to a thickness (after drying) of 0.06 μm, and then stretched 3.9 times in the transverse direction at 100 ° C. And a heat treatment at 210 ° C. to obtain a polyester film F8 having a thickness of 38 μm (thickness ratio = 2.5 μm / 33 μm / 2.5 μm).

<Manufacture of polyester film F9>
Two vented extruders using polyethylene terephthalate A1, A2, and A3 blended in proportions of 89%, 0%, and 11%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material And melt-extruded at 290 ° C., and then cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method, to obtain an amorphous film having a thickness of about 550 μm. This film was stretched 3.7 times in the machine direction at 85 ° C., and the coating liquid A was applied to a thickness (after drying) of 0.06 μm on one side of the film, and then stretched 3.9 times in the transverse direction at 100 ° C. And a heat treatment at 210 ° C. to obtain a polyester film F9 having a thickness of 38 μm (thickness ratio = 2.5 μm / 33 μm / 2.5 μm).

<Manufacture of polyester film F10>
Two vented extruders using polyethylene terephthalate A1, A2, and A3 blended in proportions of 83%, 10%, and 7%, respectively, as the surface layer material and polyethylene terephthalate A1 = 100% material as the intermediate layer material And melt-extruded at 290 ° C., and then cooled and solidified on a cooling roll having a surface temperature set to 40 ° C. using an electrostatic application adhesion method, to obtain an amorphous film having a thickness of about 550 μm. This film was stretched 3.7 times in the machine direction at 85 ° C., and coating solution A was applied to one side of the film to a thickness (after drying) of 0.06 μm, and then stretched 3.9 times in the transverse direction at 100 ° C. And a heat treatment at 210 ° C. to obtain a polyester film F9 having a thickness of 38 μm (thickness ratio = 2.5 μm / 33 μm / 2.5 μm).

Coating liquid-A
・ Polyester resin (A1) Tg = 63 ℃
Acid component: terephthalic acid 50 mol%
Isophthalic acid 48mol%
5-Na sulfoisophthalic acid 2 mol%
Diol component: Ethylene glycol 50 mol%
Neopentyl glycol 50 mol%
Particle (B): Colloidal silica (Nissan Chemical: Snowtex “YL” average particle size 70 nm)
Coating liquid-A was prepared at a blending ratio of A1 / B = 95/5.

Release layer composition-A
Curable 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
Curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical) 100 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical) 10 parts MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts Release layer composition -C
Curable silicone resin (KS-723A: manufactured by Shin-Etsu Chemical) 100 parts Curable silicone resin (KS-723B: manufactured by Shin-Etsu Chemical) 5 parts Curing agent (PS-3: manufactured by Shin-Etsu Chemical) 5 parts MEK / toluene mixed solvent (mixed) The ratio is 1: 1) 1500 parts

Release layer composition-D
Curing type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical Co., Ltd.) 95 parts Heavy release control agent (BY24-4980: manufactured by Toray Dow Corning) 5 parts Curing agent (PL-50T: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part MEK / toluene mixed solvent (Mixing ratio is 1: 1) 1500 parts release layer composition-E
Curable silicone resin (KS-847H: manufactured by Shin-Etsu Chemical) 95 parts Heavy release control agent (BY24-4980: manufactured by Toray Dow Corning) 3 parts Hardener (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (Mixing ratio is 1: 1) 1500 parts release layer composition-F
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 Co., Ltd.) 1 part MEK / toluene mixed solvent (Mixing ratio is 1: 1) 1500 parts

Example 1:
<Manufacture of first release film>
By using the reverse gravure coating method off-line so that the amount of the release layer composition-A applied to the film surface of the polyester layer 5 on which the coating layer is not provided is 0.1 g / m ² (after drying). After coating, heat treatment was performed at 120 ° C. for 30 seconds. From the above, the characteristics of the obtained first release film are shown in Tables 2 and 3 below.
<Manufacture of second release film>
A release layer composition-D is applied to a polyester film 1 having a thickness of 125 μm on a film surface on which no coating layer is provided so that the coating amount is 0.1 g / m ² (after drying). A mold film was obtained. The characteristics of the obtained second release film are shown in Tables 2 and 3.
<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 A pressure-sensitive adhesive layer having a coating amount (after drying) of 150 μm was obtained by heat treatment for minutes.

<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, the release layer and adhesive layer of the 1st release film were bonded together using the 2 kg rubber roller, and the base material-less double-sided adhesive sheet was obtained.

Examples 2-12 and Comparative Examples 1-2:
In Example 1, it manufactured like Example 1 except changing a mold release agent composition and a polyester film base material thickness as shown in following Table 1, and obtained the 1st mold release film and the 2nd mold release film. . Then, it bonded together through the adhesion layer using both, and obtained the base material-less double-sided adhesive sheet. Tables 1 and 2 show the characteristics of the release films obtained in the above Examples and Comparative Examples.

  The present invention relates to a substrate-less double-sided pressure-sensitive adhesive sheet, has good releasability, and has inspection ease in an inspection process involving optical evaluation. For example, as a capacitive touch panel member, It can be suitably used as an adhesive sheet.

Claims (1)

It is a substrate-less double-sided pressure-sensitive adhesive sheet in which release films are laminated on both sides of an adhesive layer. One release film has a release layer on one side of a biaxially stretched polyester film, and the film internal haze is 0 A substrate-less double-sided pressure-sensitive adhesive sheet characterized by having a maximum surface roughness (Rt) of 300 nm or more on the surface of the film that is .8% or less and on which no release layer is provided.