JP2011245739A - Mold release film for double-sided adhesive sheet without substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold release film for a double-sided adhesive sheet without a substrate which has few foreign substances due to an oligomer in an adhesive layer and is suitable for production of various kinds of display constitution members such as for production of a liquid crystal constitution member such as a touch panel, a liquid crystal polarizing plate and a retardation plate, for production of a PDP (Plasma Display Panel) constitution member and for production of an organic EL (ElectroLuminescence) constitution member and further for various kinds of optical uses.SOLUTION: The mold release film for the double-sided adhesive sheet without the substrate is the mold release film laminated on an adhesive layer surface of the double-sided adhesive sheet without the substrate, the mold release film has a coating layer on one surface of a biaxially oriented polyester film and has a mold release agent layer on the other surface thereof. Amount of the oligomer in a coating layer surface is 3.0 mg/mor less after heated at 180°C for 10 minutes.

Description

  The present invention relates to a release film used for a substrate-less double-sided pressure-sensitive adhesive sheet, and particularly relates to a release film that minimizes the amount of oligomers deposited on the surface of an anti-release layer, for example, a touch panel, a liquid crystal display (hereinafter abbreviated as LCD). For substrate-less double-sided pressure-sensitive adhesive sheets used for optical applications such as plasma display panels (hereinafter sometimes abbreviated as PDP) and organic electroluminescence (hereinafter sometimes abbreviated as organic EL). It is related with the release film suitable for.

  Conventionally, various pressure-sensitive adhesive sheets for surface bonding between objects are known, and a base-less double-sided pressure-sensitive adhesive sheet is one of the pressure-sensitive adhesive sheets.

  The substrate-less double-sided pressure-sensitive adhesive sheet is configured by laminating a light release sheet having a relatively low peeling force and a heavy release sheet having a relatively high peeling force on both sides of the pressure-sensitive adhesive layer, and removing the double-sided release sheet. The latter is a double-sided pressure-sensitive adhesive sheet that only has a pressure-sensitive adhesive layer that does not have a supporting substrate.

  The substrate-less double-sided PSA sheet is first peeled off from the light release sheet, and one side of the exposed PSA layer is bonded to the object surface. The other side of the layer is bonded to a different object surface, thereby surface bonding between the objects.

  In recent years, the use of a baseless double-sided pressure-sensitive adhesive sheet has been spreading, and is also used for members for various optical applications. For example, when using a polarizing plate on one side of a substrate-less double-sided adhesive as the LCD member and a release film on the opposite side, it is easy to detect defects such as foreign matter when inspecting with the crossed Nicols method A proposal has been made to reduce the inclination of the orientation main axis of a biaxially oriented polyester film used for a release film (for example, Patent Document 1).

  Thus, when using the substrate-less double-sided pressure-sensitive adhesive sheet for optical applications, not only the substrate-less double-sided pressure-sensitive adhesive sheet, but also the release film used for it is more problematic than ever with defects such as foreign matter. It has become.

  As one of the causes of the generation of foreign substances, an oligomer contained in a biaxially oriented polyester film is considered. The oligomer is deposited on the film surface in the production process and adheres to a roll or the like that comes into contact with the film to become a foreign substance.

  In addition, in order to reduce foreign matter, the work to remove the oligomer attached to the roll is performed, but it is necessary to stop the production line, and there is a problem that the production efficiency is deteriorated because the removal work requires manpower and time. Can be mentioned.

JP 2009-220296 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that there are few foreign matters due to oligomers in the pressure-sensitive adhesive layer, for example, for manufacturing liquid crystal components such as touch panels, liquid crystal polarizing plates, retardation plates, Another object of the present invention is to provide a release film for a substrate-less double-sided pressure-sensitive adhesive sheet suitable for various optical uses and the like, as well as for producing various display components such as for producing members and for producing organic EL components.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the above-mentioned problems can be easily solved by a release film having a specific configuration, and has completed the present invention.

That is, the gist of the present invention is a release film laminated on the pressure-sensitive adhesive layer surface of the substrateless double-sided pressure-sensitive adhesive sheet, and the release film has a coating layer on one surface of the biaxially oriented polyester film, It has a release agent layer on one surface, and the amount of oligomer on the surface of the coating layer after heating at 180 ° C. for 10 minutes is 3.0 mg / m ² or less. Exists in the mold film.

  According to the present invention, oligomer precipitation on the surface of the release layer is suppressed even when subjected to heating in the manufacturing process of each member, and foreign substances due to oligomers are reduced for a substrate-less double-sided pressure-sensitive adhesive sheet used for optical applications. And its industrial value is high.

  The substrate-less double-sided pressure-sensitive adhesive sheet is constituted by laminating release films on both sides of the pressure-sensitive adhesive layer of the sheet.

  One release film is usually a so-called light release sheet, having a coating layer on one side of a biaxially oriented polyester film substrate, and having a release agent layer laminated on the opposite side. A mold layer is temporarily attached to one pressure-sensitive adhesive layer of the substrate-less double-sided pressure-sensitive adhesive sheet so as to be peelable.

  The other release film is usually a so-called heavy release sheet, and has a coating layer on one surface of a biaxially oriented polyester film substrate, and a release agent layer is laminated on the opposite surface. The release agent layer is temporarily attached to the other pressure-sensitive adhesive layer of the substrate-less double-sided pressure-sensitive adhesive sheet so as to be peelable.

  As the polyester forming the release film substrate of the present invention, typically, for example, polyethylene terephthalate in which 80 mol% or more of the structural unit is ethylene terephthalate, and 80 mol% or more of the structural unit is ethylene-2,6. -Polyethylene-2,6-naphthalate which is naphthalate, poly-1,4-cyclohexanedimethylene terephthalate in which 80 mol% or more of the structural unit is 1,4-cyclohexanedimethylene terephthalate, and the like. Other examples include polyethylene isophthalate and poly-1,4-butylene terephthalate.

  Examples of copolymer components other than the above-described dominant component include propylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, neopentyl glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, Diol components such as triethylene glycol, polyethylene glycol, polytetramethylene glycol, polyalkylene glycol, isophthalic acid, 2,7-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, Esterogenic derivatives such as azelaic acid, sebacic acid, diphenyl ether dicarboxylic acid and oxymonocarboxylic acid can be used.

  Further, as the polyester, in addition to a homopolymer or a copolymer, a small proportion of a blend with another resin can also be used. Examples of resins blended with polyethylene terephthalate include various copolymerized polyethylene terephthalates such as isophthalic acid copolymer, cyclohexanedimethylene terephthalate copolymer, polyethylene glycol copolymer, polyethylene naphthalate and copolymerized polyethylene naphthalate, poly Examples include butylene terephthalate.

  The intrinsic viscosity of the polyester film used in the present invention is usually in the range of 0.40 to 0.90, preferably 0.45 to 0.80, and more preferably 0.50 to 0.70. When the intrinsic viscosity is less than 0.40, the mechanical strength of the film tends to be weakened. When the intrinsic viscosity is more than 0.90, the melt viscosity becomes high, the load on the extruder is increased, and the production cost is increased. Problems may occur.

  Conventionally, as a method of reducing the oligomer of the film, for example, a prescription is used in which the amount of oligomer in the final film is reduced by solid-phase polymerization in advance to reduce the amount of oligomer in the polymer. In this case, there is a problem that the intrinsic viscosity of the polymer becomes high or the cost increases due to an increase in the number of steps. Further, when the melting temperature is high or the residence time is long in an extruder in the film production process, the effect of reducing the oligomer is not seen.

  It is preferable to mix | blend particle | grains in the polyester layer which comprises the polyester film of this invention for the main purpose of provision of 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 manufacturing process of the film raw material.

  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 about the hardness, specific gravity, a color, etc. 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 0.05-5 micrometers normally, Preferably it is the range of 0.05-3 micrometers. If the average particle size is less than 0.05 μm, the particles tend to aggregate and the dispersibility may be insufficient. On the other hand, if it exceeds 5 μm, the surface roughness of the film becomes too rough and Problems may occur when various surface functional layers are applied in the process.

  Further, the content of particles 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 polymer constituting each layer.

  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.

  As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the substrate-less double-sided pressure-sensitive adhesive sheet, an acrylic pressure-sensitive adhesive is usually used. The acrylic pressure-sensitive adhesive is composed mainly of an acrylic copolymer obtained by copolymerizing a functional group-containing monomer and another monomer such as an acrylic ester or methacrylic ester, and if necessary, a solvent , A crosslinking agent, a tackifier, a filler, a colorant, an antioxidant, an antistatic agent, an ultraviolet absorber and the like may be further contained.

  Examples of the functional group-containing monomer include carboxyl group-containing monomers such as acrylic acid and methacrylic acid. The functional group-containing monomer preferably includes 0.3 to 5.0% by mass as a monomer unit based on the whole monomer constituting the acrylic copolymer (100% by mass).

  By containing functional groups, acrylic copolymers can adjust the cohesive force by reaction with the crosslinking agent, and prevent the adhesive from sticking out from the base material and improve the adhesive strength and heat resistance. Can be made. There is no restriction | limiting in particular as a crosslinking agent used for an adhesive, It uses suitably selecting from what was conventionally used in the acrylic adhesive conventionally, for example, a polyisocyanate compound, an epoxy resin, a melamine resin, a urea resin , Dialdehydes, methylol polymers, aziridine compounds, metal chelate compounds, metal alkoxides, metal salts and the like, preferably polyisocyanate compounds are used.

  The release film of the present invention has a coating layer on one surface of a biaxially oriented polyester film and a release agent layer on the other surface. It is preferable to have the said structure also about any release film of light peeling and heavy peeling.

  When the coating layer is not provided, the oligomer deposited from the polyester film is transferred from the film surface to the roll surface installed in the production line in the production process of the release film and the baseless double-sided pressure-sensitive adhesive sheet. The oligomer deposited on the surface is a source of foreign matter, contaminates the production line, is mixed into the product being manufactured, and becomes a defect in the final product.

  The substrate-less double-sided pressure-sensitive adhesive sheet is, for example, coated with a pressure-sensitive adhesive on a release film release layer for heavy release, and then dried to form a pressure-sensitive adhesive layer, and then on the pressure-sensitive adhesive layer. It is manufactured by laminating a release film that is lightly peeled, but when using a release film that is not provided with a coating layer, it is possible to Oligomer deposited from a certain biaxially oriented polyester film migrates to the film surface and becomes a defect in the final product.

  Further, when the substrate-less double-sided pressure-sensitive adhesive sheet is produced by a method in which a light-release release film is heated, if the release film does not have a coating layer, the same as the above heavy-release release film A phenomenon occurs.

  The coating layer preferably contains a silane compound, and the coating layer containing a silane compound is formed by using a silane coupling agent.

Silane coupling agent has at least two types of reactive functional groups different in a molecule, generally is a compound represented by YRSiX _3.

  Here, Y is an organic functional group such as a vinyl group, an epoxy group, or an amino group, R is an alkylene group such as methylene, ethylene, or propylene, and X is a hydrolyzable group such as methoxy or ethoxy, or an alkyl group. In the silane coupling agent provided in the present invention, Y is preferably an amino group. When Y is a vinyl group or an epoxy group, the sealing effect of the oligomer tends to be small.

  Specific examples of the silane coupling agent include N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, and N-β (aminoethyl) γ. -Aminopropylmethyldimethoxysilane etc. can be mentioned.

  A preferred silane coupling agent used in the present invention is a compound represented by the following general formula.

Y— (CH ₂ ) ₃ —Si— (X) ₃
(In the above formula, X represents —OCH ₃ or —OCH ₂ CH ₃ , Y represents —NH ₂ or —NHCH ₂ CH ₂ NH ₂ , and Y is preferably —NHCH ₂ CH ₂ NH ₂ ).
If necessary, a water-soluble or water-dispersible binder resin other than the silane coupling agent may be used in combination with the coating layer of the release film of the present invention.

  Examples of the binder resin include polyvinyl alcohol, polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, and amide resin. In these, each skeleton structure may have a composite structure substantially by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, and vinyl resin graft polyurethane.

  In order to further improve the prevention of oligomer precipitation on the film surface, which is the object of the present invention, it is preferable to use polyvinyl alcohol in the binder.

  The blending amount of the binder component is preferably 50 parts by weight or less, more preferably 30 parts by weight or less in terms of parts by weight with respect to the coating layer.

  Furthermore, the coating layer of the film of the present invention may contain a crosslinking reactive compound as required. Cross-linking reactive compounds include methylolated or alkylolized urea, melamine, guanamine, acrylamide, polyamide and other compounds, polyamines, epoxy compounds, oxazoline compounds, aziridine compounds, blocked isocyanate compounds, silane cups Polyfunctional low molecular weight compounds such as ring agents, titanium coupling agents, zirco-aluminate coupling agents, metal chelates, organic acid anhydrides, organic peroxides, thermally or photoreactive vinyl compounds and photosensitive resins, and It is selected from polymer compounds.

  The crosslinking reactive compound mainly improves the cohesiveness, surface hardness, scratch resistance, solvent resistance, and water resistance of the coating layer by crosslinking reaction with the functional group of the resin contained in the coating layer. . For example, when the functional group is a hydroxyl group, the crosslinking reactive compound is preferably a melamine compound, a blocked isocyanate compound, an organic acid anhydride, or the like, and when the functional group is an organic acid or an anhydride thereof, the crosslinking reactive compound. Is preferably an epoxy compound, a melamine compound, an oxazoline compound, a metal chelate, etc. When the functional group is an amine, an epoxy compound or the like is preferred as a crosslinking reactive compound, and the resin contained in the coating layer has It is preferable to select and use a functional group and one having a high crosslinking reaction efficiency.

  The crosslinking reactive compound may be either a low molecular weight compound or a high molecular polymer having a reactive functional group as long as two or more reactive functional groups are contained in one molecule.

  The blending amount of the crosslinking reactive compound is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and particularly preferably 15 parts by weight or less in terms of parts by weight with respect to the coating layer.

  Furthermore, the coating layer of the present invention may contain inert particles for improving the slipperiness of the coating layer, if necessary.

  The thickness of the coating layer is preferably 0.01 to 2 μm, more preferably 0.03 to 0.5 μm, and particularly preferably 0.06 to 0.2 μm. When the thickness of the coating layer is less than 0.01 μm, sufficient effect of preventing oligomer precipitation may not be obtained, and when it exceeds 2 μm, the blocking resistance tends to be insufficient.

Release film of the present invention is an oligomer of 180 ° C. for 10 minutes the coating layer surface after heat treatment 3.0 mg / ^{m 2} or less, preferably 1.60 mg / ^{m 2} or less, more preferably 1.00 mg / m ² or less. When the amount of the surface oligomer exceeds 3.00 mg / m ² , in the production process of the release film or the substrate-less double-sided pressure-sensitive adhesive sheet, the roll contacting with the film surface becomes dirty or the oligomer precipitated from the polyester film Since it migrates to the surface and the migrated oligomer becomes a foreign substance and becomes a defect in the final product, it is not preferable. The release layer of the release film of the present invention is not particularly limited as long as it contains a material having releasability. Among them, the one containing a curable silicone resin is preferable because the releasability is improved. A type having a curable silicone resin as a main component may be used, 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 the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet ray 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, Dow manufactured by Shin-Etsu Chemical Co., Ltd. -Corning Asia Co., Ltd. DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210, Toshiba Silicone Co., Ltd. YSR-3022, TPR-6700, TPR-6720, TPR-6721, Toray Dow Corning Co., Ltd. SD7220, SD7226, SD7229, etc. are mentioned. Further, a release control agent may be used in combination to adjust the release property of the release layer.

  In the present invention, as a method for providing a release layer on the polyester film, a conventionally known coating method such as reverse roll coating, gravure coating, bar coating, doctor blade coating, or the like can be used.

The coating amount of the release layer of the release film of the present invention is generally in the range of 0.01 to 1 g / ^{m 2.}

  In the present invention, the surface on which the release layer is provided may be provided with a coating layer such as an adhesive layer, an antistatic layer or a coating layer, and the polyester film is subjected to a surface treatment such as corona treatment or plasma treatment. Also good.

  3-50 mN / cm is preferable and, as for the peeling force with respect to the adhesive layer of a light release mold release film, More preferably, it is 5-25 mN / cm. By suppressing the release force of the light release film to a low level, the difference in release force between the release films can be increased even if the release force of the heavy release film is reduced.

  In addition, by making the release force of the light release film more than a certain value, it is possible to prevent the release film from being unexpectedly peeled off from the pressure-sensitive adhesive layer or floating from the pressure-sensitive adhesive layer before use. .

  10-100 mN / cm is preferable and, as for the peeling force with respect to the adhesive layer of the release film of a heavy peeling, More preferably, it is 15-50 mN / cm. By keeping the release force of the release film of the heavy release low, it is possible to prevent the adhesive film from remaining when the release film is peeled off, so-called zipping or the like.

  The thickness of the release film of the present invention is not particularly limited as long as it can be formed as a film and can be processed as a release film, but is usually 10 to 100 μm, preferably 15 to 15 μm. The range is 50 μm. If the film thickness is less than 10 μm, the film may not be elastic, and trouble may occur in the process of peeling the release film. If the film thickness exceeds 100 μm, the manufacturing cost will increase.

  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.

  That is, 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 film is stretched in the direction perpendicular to the first stretching direction. In that case, the stretching temperature is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. is there. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or under 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.

  In the present invention, the simultaneous biaxial stretching method can also be adopted for the production of the polyester film constituting the release film. The simultaneous biaxial stretching method is a method in which the unstretched sheet is usually stretched and oriented in the machine direction and the width direction at 70 to 120 ° C., preferably 80 to 110 ° C., and stretch ratio. As an area magnification, it 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 conventionally known stretching method such as a screw method, a pantograph method, or a linear driving method can be employed.

  Although the method in particular of forming a coating layer on the surface of a polyester film is not restrict | limited, The method of apply | coating a coating liquid in the process of manufacturing a polyester film is employ | adopted suitably. Specifically, a method of applying and drying a coating solution on the surface of an unstretched sheet, a method of applying and drying a coating solution on the surface of a uniaxially stretched film, and a method of applying and drying a coating solution on the surface of a biaxially stretched film Etc. Among these, it is economical to apply a coating solution on the surface of an unstretched film or a uniaxially stretched film, and then simultaneously dry and cure the coating layer in the process of heat-treating the film.

  Moreover, as a method for forming the coating layer, a method in which some of the above-described coating methods are used in combination can be adopted as necessary. Specifically, a method of applying a first layer on the surface of an unstretched sheet and drying, then stretching in a uniaxial direction, and then applying and drying a second layer can be used.

  Use the reverse roll coater, gravure coater, rod coater, air doctor coater, etc. shown in “Coating Method” by Yuji Harasaki, Tsuji Shoten, published in 1979, as a method of applying the coating solution to the surface of the polyester film. Can do.

  The coating solution used in the present invention is usually preferably adjusted with water as the main medium from the viewpoint of safety and hygiene. As long as water is the main medium, a small amount of an organic solvent may be contained for the purpose of improving the dispersion in water or improving the film forming performance. The organic solvent is preferably used as long as it is dissolved in water when mixed with water, which is the main medium. However, if it is a stable emulsion (emulsion) that does not separate after standing for a long time, Alternatively, it may be used in a state where it does not dissolve in water. The organic solvent may be used alone or in combination of two or more as necessary.

  Next, the present description will be further described with reference to examples. However, the present invention is not limited to the following examples without departing from the gist thereof. In addition, the evaluation method of the physical property in a following example and a comparative example is as follows.

(1) Measurement of Intrinsic Viscosity of Polyester 1 g of polyester 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) Average particle diameter (d50)
The average particle size d50 was defined as the particle size having an integrated volume fraction of 50% in an equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution analyzer (SA-CP3 type) manufactured by Shimadzu Corporation.

(3) Heat treatment of film A4 size Kent paper and polyester film to be heat treated are combined. At that time, clip the four corners with a gem clip or the like so that the surface with the coating layer is on the outside, and stop the Kent paper and the polyester film. Under a nitrogen atmosphere, the polyester film is left in an oven at 180 ° C. for 10 minutes to perform heat treatment.

(4) Film surface oligomer amount after heat treatment Fold the polyester film after heat treatment so that the upper part is opened and the area of the bottom side is 250 cm ² to create a square box. When the coating layer is provided, the coating layer surface is set to the inside. Next, 10 ml of DMF is put in the box prepared by the above method, and the DMF is recovered after being left for 3 minutes. The recovered DMF is supplied to liquid chromatography (Shimadzu LC-7A) to determine the amount of oligomer in DMF, and this value is divided by the film area in contact with DMF to obtain the amount of oligomer on the film surface (mg / m ² ). To do. 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 mg / ml to 0.01 mg / ml.

The conditions of 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

(5) Evaluation of release film peeling force (F) After attaching one side of a double-sided adhesive tape (Nitto Denko “No. 502”) to the surface of the release layer of the sample film, cut into a size of 50 mm × 300 mm After that, the peel strength after standing for 1 hour at room temperature is measured. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min.

(6) Practical properties <Roll contamination status>
When the release film was produced, each roll of the production apparatus was visually observed to evaluate the state of contamination of the roll with the oligomer.
○: No deposits are observed on the roll surface after production. Δ: Slight deposits are observed on the roll surface after production, but there is no problem in production.
X: Deposits are observed on the roll surface after production, and roll cleaning is required

<Foreign matter inspection>
The substrate-less double-sided pressure-sensitive adhesive sheet provided with release films on both sides was observed and evaluated based on the detection of foreign matter.
○: No foreign matter is detected, and the quality is sufficient for optical use. △: Foreign matter is detected, but there is no practical problem. ×: Many foreign matters are detected, which is inappropriate for optical use. Limited use

The production methods of polyester used in the following examples and comparative examples are as shown below.
[Production method of polyester (1)]
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst is placed in the reactor, the reaction start temperature is set to 150 ° C., and the methanol is distilled off gradually. The reaction temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part of ethyl acid phosphate to the reaction mixture, 0.06 part of silica particles dispersed in ethylene glycol having an average particle diameter of 1.6 μm and 0.04 part of antimony trioxide were added, and 4 A time polycondensation reaction was performed. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After 4 hours from the start of the reaction, the reaction was stopped and the polymer was discharged under nitrogen pressure. The obtained polyester (1) had an intrinsic viscosity of 0.53 and an oligomer (cyclic trimer) content of 0.98% by weight.

The adjustment method of the coating liquid used in the following examples and comparative examples is as shown below.
-Preparation of coating solution A A coating solution containing 90% by weight of N-β (aminoethyl) γ-aminopropyltrimethoxysilane and 10% by weight of PVA resin was prepared. The solid content concentration of the coating solution was 2% by weight.
-Preparation of coating solution B A coating solution containing 90% by weight of N-β (aminoethyl) γ-aminopropyltriethoxysilane and 10% by weight of PVA resin was prepared. The solid content concentration of the coating solution was 2% by weight.
-Preparation of coating solution C A coating solution containing 90% by weight of γ-aminopropyltrimethoxysilane and 10% by weight of PVA resin was prepared. The solid content concentration of the coating solution was 2% by weight.

-Preparation of coating solution D A coating solution containing 90% by weight of N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane and 10% by weight of PVA resin was prepared. The solid content concentration of the coating solution was 2% by weight.
-Preparation of coating solution E A coating solution containing 90% by weight of γ-glycidoxypropyltriethoxysilane and 10% by weight of PVA resin was prepared. In the liquid adjustment of γ-glycidoxypropyltriethoxysilane, since it is difficult to dissolve in pure water, a 2% acetic acid aqueous solution was used as a dilution liquid for concentration adjustment. The solid content concentration of the coating solution was 2% by weight.
-Adjustment of coating solution F A coating solution containing 20% by weight of PVA resin, 70% by weight of water-based polyester, and 10% by weight of a crosslinkable compound described below was prepared. The solid content concentration of the coating solution was 2% by weight.

<PVA resin>
Polyvinyl alcohol having a degree of saponification = 88 mol% and a degree of polymerization = 500 <water-based polyester>
An aqueous system obtained by neutralizing a polyester mainly composed of isophthalic acid, ethylene glycol and diethylene glycol with a dicarboxylic acid derivative having neopentyl glycol and an aliphatic dicarboxylic acid anhydride with an amine compound to form an aqueous system. Polyester <Crosslinkable compound>
Hexamethoxymethylmelamine

-Adjustment of coating liquid G Polyurethane water dispersion A (Dainippon Chemical Co., Ltd. Hydran AP-40) 80 parts, polyester water dispersion B (Dainippon Chemical Co., Ltd. Finetex ES-670) A coating solution containing 20 parts was prepared. The solid concentration in the coating solution was 2% by weight.

Example 1:
Polyester (1) as a raw material is supplied to an extruder with a vent, 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. An amorphous film of about 550 μm was obtained. The film was stretched 3.7 times in the machine direction at 85 ° C., and the coating solution A was applied to a thickness of 0.06 μm on one side of the film, then stretched 3.9 times in the transverse direction at 100 ° C., and 210 ° C. A biaxially stretched polyester film 1 having a thickness of 38 μm was obtained by heat treatment.

A release layer having the following composition is provided on the opposite surface of the resulting polyester film 1 coating layer so that the coating amount is 0.1 g / m ² (after drying), and the first release film and the second release film are provided. Each mold film was obtained. The properties of the obtained release film are shown in Table 1 below.

Release agent composition of the first release film Curing type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical) 100 parts Hardening agent (PL-50T: manufactured by Shin-Etsu Chemical) 1 part MEK / toluene mixed solvent (mixing ratio is 1: 1) 1500 parts-Parting agent composition of second release film Curing type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical) 95 parts Heavy release control agent (SD-7292: 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

  On the release agent layer of the obtained second release film, the acrylic pressure-sensitive adhesive solution was applied using an applicator so that the film thickness after drying was 25 μm. The adhesive layer was formed by drying at 120 ° C. for 1 minute.

The acrylic pressure-sensitive adhesive solution was prepared by adding polyisocyanate-based crosslinking to 100 parts by mass of a copolymer solution (solvent: toluene, solid content concentration: 40% by mass) having a monomer-based mass ratio of butyl acrylate and acrylic acid of 99: 1. It was obtained by adding 1 part by weight of an agent (manufactured by Toyo Ink Manufacturing Co., Ltd., trade name “BHS8515”, solid content concentration 37.5% by mass).
Subsequently, the mold release agent layer and adhesive layer of the 1st release film were bonded together, and the base material-less double-sided adhesive sheet was obtained.

Example 2:
In the production of the polyester film 1 of Example 1, a substrate-less double-sided PSA sheet was obtained in the same manner as in Example 1 except that the coating liquid A was changed to the coating liquid B.

Example 3:
In the production of the polyester film 1 of Example 1, a polyester film 2 was obtained in the same manner as in Example 1 except that the application performed after the longitudinal stretching was not performed. In the production of the release film of Example 1, a release film was obtained in the same manner as in Example 1 except that the polyester film 1 of the first release film was changed to the polyester film 2. A substrate-less double-sided pressure-sensitive adhesive sheet was obtained.

Example 4:
In the production of the polyester film of Example 1, a substrate-less double-sided pressure-sensitive adhesive sheet of Example 4 was obtained in the same manner as in Example 1 except that the coating liquid A was changed to the coating liquid F.

Example 5:
A substrate-less double-sided PSA sheet of Example 5 was obtained in the same manner as in Example 1 except that the coating liquid A was changed to the coating liquid C in the production of the polyester film 1 of Example 1.

Example 6:
In the production of the release film of Example 1, the base material of Example 6 is the same as Example 1 except that the polyester film 1 used for the first release film is changed to the polyester 2 produced in Example 3. A double-sided pressure-sensitive adhesive sheet was obtained.

Example 7:
A substrate-less double-sided PSA sheet of Example 7 was obtained in the same manner as in Example 1 except that the coating liquid A was changed to the coating liquid G in the production of the polyester film 1 of Example 1.

Comparative Example 1:
In the production of the release film of Example 1, a substrate-less double-sided pressure-sensitive adhesive sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that the polyester film 1 was changed to the polyester 2 produced in Example 3. .

  The evaluation results of the films obtained in each Example and Comparative Example are summarized in Tables 1 and 2 below.

  The release film of the present invention can be suitably used as, for example, a release film for a substrate-less double-sided pressure-sensitive adhesive sheet used for optics.

Claims (3)

It is a release film laminated on the adhesive layer surface of a substrate-less double-sided adhesive sheet, and the release film has a coating layer on one surface of a biaxially oriented polyester film, and a release agent layer on the other surface A release film for a substrate-less double-sided pressure-sensitive adhesive sheet, wherein the amount of oligomer on the surface of the coating layer after heating at 180 ° C. for 10 minutes is 3.0 mg / m ² or less. The release film for base-material-less double-sided adhesive sheets of Claim 1 in which an application layer contains a silane compound. The release film for base-material-less double-sided adhesive sheets of Claim 2 in which a silane compound has an amino group.