WO2012090762A1 - Mold release film - Google Patents

Abstract

Provided is an inexpensive mold release film, whereby it becomes possible to minimize the peel rate dependency when a base-less double-sided adhesive sheet is used for optical purposes, for example in a touch panel, a liquid crystal polarizing plate and a retardation plate, to improve the productivity, cost performance or the like of the mold release film, and to impart a property of preventing the formation of any oligomer or a property of testing on the formation of any oligomer to the mold release film to thereby reduce the occurrence of contamination during a process or the formation of foreign substances in an adhesive agent. A mold release film comprising a polyester film having a mold release layer, wherein the mold release layer is bonded to an adhesive layer in a base-less double-sided adhesive sheet upon use, the mold release layer is a silicone-type mold release layer comprising (a) a silicone resin having an alkenyl group as a functional group, (b) a silicone resin having an alkyl group as a functional group, (c) a component capable of migrating into the adhesive layer, and (d) a platinum-containing catalyst, the content of the component (c) capable of migrating is 5-20 wt%, the low-speed peel force of the mold release layer at a speed of 300 mm/min falls within the range of 10-20 mN/cm, and the high-speed peel force of the mold release layer at a speed of 10000 mm/min is up to 2.5 times greater than the low-speed peel force.

Description

Release film

The present invention relates to a release film, and more particularly to a release film used for a substrate-less double-sided pressure-sensitive adhesive sheet suitable for optical applications.

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 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 baseless double-sided pressure-sensitive adhesive sheet has been used for various optical applications and the like. For example, as the LCD member, peel off the release film with the lighter peeling force of the base-less double-sided pressure-sensitive adhesive sheet, paste the polarizing plate on the surface, and release the heavy release force on the opposite side. May be used.

In terms of workability in production, processing in a high speed range can be considered to some extent, but in the release film of light release, of course, to achieve a light release force, It is very difficult to simultaneously achieve that the difference in peel force from the release film that is as heavy as possible is not reduced (Patent Document 1). If the peel force difference with the heavy release film is reduced, there will be problems such as the film on both sides being peeled off at the same time in the peeling process, and the adhesive being peeled off together because the peel force difference is small. This will cause problems in workability and productivity (Patent Document 2).

It is very difficult to control the above difference in peeling force, and various selection and control of the silicone component are necessary (Patent Documents 1 and 2), and it is also considered necessary to control the hardness of the silicone coating film.

Also, in applications that are used on the outside of a flat panel with a relatively small area, such as a touch panel and a monitor, in a baseless double-sided pressure-sensitive adhesive sheet, human eyes are close when the product is used, and if bright spots such as foreign objects are noticeable, it is visually In some cases, the inspection may be strengthened due to problems. At this time, the inspection may be performed while the release film is bonded to the baseless double-sided pressure-sensitive adhesive sheet. In that case, as a matter of course, it is necessary to manage the optical axis of the film, that is, the orientation of the molecule for the purpose of facilitating inspection (Patent Document 3).

Furthermore, one of the foreign substances described above may be caused by a low molecular component called an oligomer derived from a polyester film. If this oligomer can be prevented, the above-mentioned foreign matter malfunction during production can be suppressed, and the film and the subsequent process contamination can be prevented. In the present invention, the oligomer (OL) is defined as a cyclic trimer among low molecular weight substances that crystallize after heat treatment and precipitate on the film surface.

JP 2009-220696 A Japanese Patent Laid-Open No. 10-158519 JP 2003-231214 A

The present invention has been made in view of the above circumstances, and the problem to be solved is that the substrate-less double-sided pressure-sensitive adhesive sheet depends on the peeling rate when used in optical applications, for example, touch panels, liquid crystal deflecting plates, retardation plates, and the like. It is possible to minimize productivity, solve problems such as productivity, cost, etc., and provide oligomers with preventability and inspection properties, thereby reducing process contamination and foreign substances to adhesives. The object is to provide an inexpensive release film.

As a result of intensive studies in view of the above circumstances, the present inventor has found that the above problem can be easily solved by a polyester film having a release layer having a specific configuration, and has completed the present invention.

That is, the gist of the present invention is a release film composed of a polyester film provided with a release layer, which is used by laminating the release layer to the adhesive layer of the base-less double-sided pressure-sensitive adhesive sheet. A silicone resin (a) having an alkenyl group as a group, a silicone resin (b) having an alkyl group, a migration component (c) to the adhesive layer, and a platinum-based catalyst (d), and containing the migration component (c) It is a silicone-based release layer having a content of 5 to 20% by weight, and the release layer has a low-speed peeling force in the range of 300 mm / min at a speed range of 10 to 20 mN / cm, and a speed range of 10,000 mm / min. The release film is characterized in that the high-speed peeling force is 2.5 times or less of the low-speed peeling force.

And in the layer structure of the preferable aspect of this invention, it has a coating layer obtained by apply | coating the coating liquid containing polyvinyl alcohol between a polyester film and a silicone type release layer.

According to the present invention, it is possible to provide a release film that is lightly peeled and has a small peel rate dependency, and therefore has high industrial value.

<Polyester film>
The polyester film which is the base material of the release film of the present invention is a film obtained by stretching a sheet melt-extruded from an extrusion die according to a so-called extrusion method.

The polyester constituting the film refers to a polymer containing an ester group obtained by polycondensation from dicarboxylic acid and diol or from hydroxycarboxylic acid.
Dicarboxylic acids include terephthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc., and diols include ethylene glycol, 1,4-butane. Examples include diol, diethylene glycol, triethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, and polyethylene glycol. Examples of hydroxycarboxylic acid include p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. be able to. Typical examples of such polymers include polyethylene terephthalate and polyethylene-2,6-naphthalate.

In the film, it is preferable to incorporate particles mainly for the purpose of imparting slipperiness and preventing scratches in each step. 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, heat-resistant organic particles as 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, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

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

The average particle diameter of the particles is usually in the range of 0.01 to 3 μm, preferably 0.1 to 2 μm. When the average particle size is less than 0.01 μm, the slipperiness may not be sufficiently imparted. On the other hand, when the thickness exceeds 3 μm, transparency may be lowered due to the aggregate of the particles when the film is formed, and it is easy to cause breakage, which causes a problem in terms of productivity. There is.

Further, the particle content 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 a case.

The method of blending particles in the film 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, but it is preferably added after completion of the esterification or 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, heat stabilizers, lubricants, dyes, pigments and the like can be added to the film as necessary.

The thickness of the polyester film is not particularly limited as long as it can be formed as a film, but is usually 10 to 350 μm, preferably 38 to 125 μm, and more preferably 50 to 100 μm. If the film thickness is less than 10 μm, external foreign matter generated in the process etc. will be transferred to the adhesive when processing the adhesive sheet in this application, and the coatability is poor during the release film processing. There are problems such as deteriorating productivity. When the film thickness is thick, a costly problem arises.

Next, a production example of the polyester film will be specifically described, but is not limited to the following production example. 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 preferable 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 is 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 90 to 140 ° C., preferably 95 to 120 ° 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 this case, the stretching temperature is usually 90 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 relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

Also, for the production of a polyester film, a simultaneous biaxial stretching method can be employed. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is stretched and oriented in the machine direction and the width direction at a temperature controlled usually at 90 to 140 ° C., preferably 80 to 110 ° C. Is an area magnification of 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.

<Coating layer obtained by applying a coating solution containing polyvinyl alcohol>
In addition to the purpose of OL sealing, the coating layer is provided to prevent process contamination due to OL and contamination when bonded to the pressure-sensitive adhesive layer.

The content of polyvinyl alcohol in the coating layer is usually 10 to 100% by weight, preferably 20 to 90% by weight, more preferably 30 to 90% by weight. If the content of polyvinyl alcohol is less than 10% by weight, the oligomer sealing effect is insufficient, which is not preferable.

Polyvinyl alcohol can be synthesized by a normal polymerization reaction and is preferably water-soluble. The degree of polymerization of polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably 300 to 40,000. When the degree of polymerization is 100 or less, the water resistance of the coating layer tends to decrease. The saponification degree of polyvinyl alcohol is not particularly limited, but is usually 70 mol% or more, preferably 80 mol% or more and 99.9 mol% or less.

In the coating layer, if necessary, a water-soluble or water-dispersible binder resin other than the polyvinyl alcohol may be used in combination. Binder resin is a polymer compound safety evaluation flow scheme (November 1985, sponsored by the Chemical Substances Council) with a high number average molecular weight (Mn) of 1000 or more by gel permeation chromatography (GPC) measurement. It can be defined as a molecular compound having film-forming properties. Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, acrylate resin, and the like. 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, vinyl resin graft polyurethane, and acrylate resin graft polyethylene glycol. The blending amount of the binder component is preferably 50 parts by weight or less, and more preferably 30 parts by weight or less, by weight with respect to the coating layer.

Furthermore, the coating layer may contain a crosslinking reactive compound as required. Cross-linking reactive compounds include methylolated or alkylolized urea-based, melamine-based, guanamine-based, acrylamide-based, polyamide-based compounds, polyamines, epoxy compounds, oxazoline compounds, aziridine compounds, blocked isocyanate compounds, silane cups Polyfunctional low molecular 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 can improve 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 of the easily adhesive resin 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 the functional group of the easily adhesive polyester is an organic acid or an anhydride thereof. In this case, epoxy-based compounds, melamine-based compounds, oxazoline-based compounds, metal chelates and the like are preferable as the cross-linking reactive compound. When the functional group of the easy-adhesion resin is an amine, an epoxy-based compound is preferable as the cross-linking reactive compound. It is preferable to select and use a functional group contained in the easily adhesive resin and one having a high crosslinking reaction efficiency. Examples of the melamine compound include methoxymethyl melamine and butoxymethylated melamine which are alkylol or alkoxyalkylol melamine compounds, and those obtained by co-condensing urea or the like with a part of melamine can also be used.

The cross-linking reactive compound may be either a low molecular weight compound or a high molecular polymer having a reactive functional group, as long as the reactive functional group always contains two or more functional groups 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.

When the binder resin and the cross-linking agent are blended in an arbitrary ratio, the coating layer forms a barrier layer densely, so that OL can be more effectively suppressed. For this reason, there is an effect that OL from the polyester film is not attached to the adhesive as much as possible and is not produced in the previous processing step.

The coating layer may contain inert particles for improving the slipperiness of the coating layer as necessary. Examples of the inert particles include inorganic inert particles and organic inert particles. Examples of the inorganic inert particles include silica sol, alumina sol, calcium carbonate, and titanium oxide. Examples of the organic inert particles include fine particles containing a single or copolymer of polystyrene resin, polyacrylic resin, and polyvinyl resin, or organic particles represented by crosslinked particles in which these and a crosslinking component are combined. These inert particles preferably have a softening temperature or decomposition temperature of about 200 ° C. or higher, more preferably 250 ° C. or higher, particularly 300 ° C. or higher. The average particle diameter (d) of the inert particles has a relationship of 1/3 ≦ d / L ≦ 3, and further 1/2 ≦ d / L ≦ 2, when the average film thickness of the coating layer is (L). It is preferable to select so as to satisfy.

The coating layer is a surfactant, antifoaming agent, coating property improver, thickener, low molecular antistatic agent, organic lubricant, antioxidant, ultraviolet absorber, foaming agent, dye, pigment as necessary A small amount of such additives may be contained. These additives may be used alone or in combination of two or more as necessary. The coating layer may be formed only on one side of the polyester film or on both sides. In the case of forming only on one side, another type of coating layer can be formed on the opposite side as required, and further properties can be imparted. In addition, in order to improve the applicability | paintability and adhesiveness to the film of a coating liquid, you may give a chemical process, an electrical discharge process, etc. to the film before application | coating.

The coating solution used for forming the coating layer 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.

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 method of providing the coating layer is not particularly limited, but a method of applying a coating solution (in-line coating) in the process of manufacturing the polyester film is suitably employed. 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.

When providing a coating layer by in-line coating, apply the above-mentioned series of compounds as an aqueous solution or water dispersion on a polyester film with a coating solution adjusted to a solid content concentration of about 0.1 to 50% by weight. It is preferable to produce a laminated polyester film. Moreover, in the range which does not impair the main point of this invention, a small amount of organic solvents may be contained in the coating liquid for the purpose of improving dispersibility in water, improving film-forming properties, and the like. Only one type of organic solvent may be used, or two or more types may be used as appropriate.

The drying and curing conditions for forming the coating layer on the polyester film are not particularly limited. For example, when the coating layer is provided by in-line coating, the standard is usually 70 to 280 ° C. for 3 to 200 seconds. It is better to perform heat treatment. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. Furthermore, the polyester film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

When the release film has a coating layer containing polyvinyl alcohol, the amount of OL extracted from the coating layer surface with dimethylformamide after heat treatment (180 ° C., 10 minutes) is 1.0 mg / m ² or less. Preferably there is. When OL exceeds 1.0 mg / m ² , there is a process contamination, and when the adhesive is bonded, a foreign matter may be generated, resulting in a problem such as a decrease in product yield.

The thickness of the coating layer is usually in the range of 0.002 to 1.0 g / m ² , preferably 0.005 to 0.5 g / m ² , more preferably 0.01 to 0.2 g / m ² . If the film thickness is less than 0.002 g / m ^2, sufficient adhesion may not be obtained, and if it exceeds 1.0 g / m ² , the appearance, transparency, and film blocking properties may be deteriorated. There is sex. Analysis of the components in the coating layer can be performed by surface analysis such as TOF-SIMS.

In the present invention, a film having a structure in which a polyester having a low OL content is coextruded and laminated on at least one surface of a layer composed of a polyester having a normal OL content may be used. In the release film of the present invention, the effect of preventing bright spots due to the precipitated OL is obtained, which is particularly preferable.

<Release layer>
The release layer in the present invention comprises a silicone resin (a) having an alkenyl group as a functional group, a silicone resin (b) having an alkyl group as a functional group, a migration component (c) to the adhesive layer, and a platinum catalyst ( It is a silicone release layer containing d).

First, a curable silicone resin containing an alkenyl group is a diorganopolysiloxane having a trimethylsiloxy group-blocked dimethylsiloxane / methylhexenylsiloxane copolymer (96 mol% dimethylsiloxane unit, 4 mol% methylhexenylsiloxane unit). ), Dimethylvinylsiloxy group-blocked dimethylsiloxane / methylhexenylsiloxane copolymer (97 mol% dimethylsiloxane unit, 3 mol% methylhexenylsiloxane unit), dimethylsiloxane / methyl-blocked dimethylhexenylsiloxy group blocked at both ends of the molecular chain Hexenylsiloxane copolymer (95 mol% of dimethylsiloxane units, 5 mol% of methylhexenylsiloxane units).

Next, the curable silicone resin containing an alkyl group is a trimethylsiloxy group-blocked methylhydrogenpolysiloxane having both molecular chains and trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane as both organohydrogenpolysiloxanes. Examples thereof include a polymer, a dimethylhydrogensiloxy group-capped methylhydrogen polysiloxane having both molecular chains, and a dimethylsiloxane / methylhydrogensiloxane copolymer having both molecular chains having both ends dimethylhydrogensiloxy group-capped.

The release film of the present invention is used by sticking the release layer to the adhesive layer of the base-less double-sided pressure-sensitive adhesive sheet, but the above-mentioned silicone resin contains a component that migrates to the adhesive layer. Silicone oil is typically used as the migration component. The silicone oil is a silicone oil called straight silicone oil or modified silicone oil, and examples thereof include the following. Examples of the straight silicone include dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, and the like. Further, as modified silicone oil, side chain type polyether modified, aralkyl modified, fluoroalkyl modified, long chain alkyl modified, higher fatty acid ester modified, higher fatty acid amide modified, polyether / long chain alkyl modified / aralkyl modified, Examples include phenyl modification, polyether modification at both ends, and polyether / methoxy modification. Both straight silicone oil and modified silicone oil are non-reactive, non-functional oils.

The content of the migration component is 5 to 20% by weight, preferably 10 to 13% by weight, more preferably 0.1 to 5.0% by weight. When the content of the transition component is lower than 5%, the speed dependency described later is increased, and when it exceeds 20% by weight, the curability is remarkably lowered and the adhesion is deteriorated.

Specific examples of silicone-based resin coatings that can be used in the present invention include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X, manufactured by Shin-Etsu Chemical Co., Ltd. -62-2422, X-62-2461; DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210 manufactured by Dow Corning Asia Ltd .; YSR- manufactured by Toshiba Silicone Corp. 3022, TPR-6700, TPR-6720, TPR-6721; LTC300B, LTC303E, LTC310, LTC314, SRX357, BY24-749, SD7333, BY24-179, SP7015, SP7259, SD7220, manufactured by Toray Dow Corning Co., Ltd. SD7226, SD7229, etc.Further, a release control agent may be used in combination to adjust the release property of the release layer.

The silicone-based resin coating material is composed of a silicone resin (a) having an alkenyl group as a functional group, a silicone resin (b) having an alkyl group as a functional group, and a component (c) for transferring to an adhesive layer. The ratio of the silicone resin having an alkenyl group as (a) and the silicone resin having an alkyl group as a functional group (b) is (b) / (a) is usually 0.5 to 2 weight ratio. In the present invention, a silicone resin having an alkenyl group and an alkyl group as a functional group may be used.

As a method for providing the release layer on the polyester film, a conventionally known coating method can be used as in the case of the above-mentioned coating layer. The coating amount when forming the release layer is usually in the range of 0.01 to 1 g / m ² .

A coating layer such as an adhesive layer, an antistatic layer, and an oligomer precipitation preventing layer may be provided on the surface where the release layer is not provided, and the polyester film is subjected to a surface treatment such as corona treatment or plasma treatment. May be.

In the present invention, a platinum-based catalyst that promotes an addition-type reaction is used in order to make the release layer clean and robust. As this component, chloroplatinic acid, alcohol solution of chloroplatinic acid, a complex of chloroplatinic acid and olefin, a platinum compound such as a complex of chloroplatinic acid and alkenylsiloxane, platinum black, platinum-supported silica, platinum-supported activated carbon Is exemplified. The platinum-based catalyst content in the release layer is usually 0.3 to 3.0% by weight, preferably 0.5 to 2.0% by weight. When the platinum-based catalyst content in the release layer is lower than 0.3% by weight, there may be problems such as deterioration of the surface condition due to insufficient peeling force and insufficient curing reaction in the coating layer. On the other hand, when the platinum-based catalyst content in the release layer exceeds 3.0% by weight, the cost is increased, and the process becomes defective due to increased reactivity and generation of gel foreign matter. Sometimes.

Further, since the addition type reaction is very reactive, acetylene alcohol may be added as a reaction inhibitor in some cases. The component is an organic compound having a carbon-carbon triple bond and a hydroxyl group, preferably 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol and phenyl. It is a compound selected from the group consisting of butinol.

<Peeling force>
In the present invention, the peeling force refers to a double-sided pressure-sensitive adhesive tape (“No. 31B” manufactured by Nitto Denko) attached to the release layer surface and left at room temperature for 1 hour, and then the substrate film and the peeling angle of 180 °. The value measured with a tensile tester when the tape is peeled off at the tensile speed.

The method for adjusting the peeling force in the present invention can be achieved by selecting the composition in the release layer, but other means can also be adopted, mainly the type of release agent for the silicone release layer, It is preferable to change according to the desired peeling force. Furthermore, since the peeling force largely depends on the application amount of the release agent to be used, a method of adjusting the application amount of the release agent is more preferable.

In the present invention, Nitto Denko Corporation No. The residual adhesion rate with 31B tape is usually 65% to 90%, preferably 70% to 85%. When the residual adhesion rate is lower than 65%, the transferability is high, and the adhesive moves to roll dirt or the adhesive surface during the adhesive processing, resulting in a decrease in adhesive peeling force. Further, when the residual adhesion rate is 90% or more, the speed dependency cannot be reduced.

The value of the peel force of the release film of the present invention is such that the low speed peel force in the range of 300 mm / min is 10 to 20 mN / cm. When the peeling force is less than 10 mN / cm, the peeling force becomes too light, and the problem of peeling easily occurs even in a scene where it is not necessary to peel off. If the peel force exceeds 20 mN / cm, the difference in peel force between the release film with the greater peel force will be small, causing problems in the peel process, and the selection range for the release film with the greater peel force will be narrow. There are problems such as becoming.

Furthermore, the high speed peeling force in the 10,000 mm / min speed region taking into consideration workability is 2.5 times or less of the above low speed peeling force. If the peel force ratio is larger than 2.5 times, the peel force difference between the release film and the heavier peel force will be small, and the peel process will not be successful, or the adhesive may be peeled off. To do.

Martens hardness of the release layer of the release film of the present invention is usually 400 N / mm ² or more, preferably, 450 N / mm ² or more. When the Martens hardness of the release layer is less than 400 N / mm ² , the release film dependency of the release film increases, and the film surface is easily damaged and OL is likely to occur. May occur.

The above-mentioned Martens hardness means a hardness obtained by an instrumented indentation hardness test on a surface layer using a hardness measuring machine using a triangular pyramid indenter, and a test of 115 ° triangular pyramid indenter and 0.10 mN. It is a value measured by force.

For the release film of the present invention, foreign matter or light interference color may be generated in the optical inspection of the process depending on the application. In order to reduce the generation of foreign matter and light interference colors in optical inspection of the process, etc., it is very important to optimize the MOR_C value obtained by measuring the release film with a microwave molecular orientation meter. A means for satisfying the range of the MOR_C value of the polyester film is to appropriately select the stretching conditions for the desired film thickness during film formation.

The MOR_C value of the polyester film is usually 1.5 to 3.0, preferably 1.8 to 2.7, more preferably 2.1 to 2.4. When the MOR_C value is larger than 3.0, the release layer is not uniform, and in the case where there is an optical inspection, problems such as easy appearance of the light interference color may occur. When the MOR_C value is smaller than 1.5, there is a problem that the production yield of the release film itself is deteriorated.

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

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

(2) Measurement of average particle diameter (d50: μm):
The value of 50% of integration (weight basis) in the equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution measuring apparatus (SA-CP3 type manufactured by Shimadzu Corporation) was defined as the average particle diameter.

(3) Transmittance measurement of polyester film:
The total light transmittance of the polyester film was measured with an integrating sphere turbidimeter NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS-K7105.

(4) Heat shrinkage measurement of polyester film:
The polyester film is sampled at an arbitrary length L (cm) in the longitudinal direction (hereinafter abbreviated as MD) and the lateral width direction (hereinafter abbreviated as TD). Subsequently, the sample is heated in an oven at 160 ° C. for 5 minutes, and the sample is taken out of the oven and the length l (cm) is measured. This operation is performed three times, and the average value is adopted as the value of the heat shrinkage rate. The heat shrinkage rate can be calculated by the following formula.
Heat shrinkage rate (%) = {(L−l) / L} × 100

(5) Measurement of amount of catalyst in coating layer:
Using SAICAS, the sample film was obliquely cut to expose the cross section. Thereafter, the amount of catalyst containing platinum contained in the polyester film coating layer was determined using TOF-SIMS (time-of-flight mass spectrometry mass spectrum).

(6) Measurement of migration component amount:
Add 0.04 wt% 0.004 g of platinum catalyst to 15 g of silicone resin diluted with toluene to a solid content concentration of 4 wt%, and after stirring, put it in a box made of a sheet made of Teflon (registered trademark). Heat cure at 1 ° C. for 1 hour (Sample 1). When adding a migration component (corresponding to Comparative Example 2 described later), 30% by weight is added to the solid content of the silicone resin. Sample 1 is immersed in toluene for 1 day, and the sample taken out is dried at 120 ° C. for 30 minutes and allowed to cool to room temperature (sample 2). The component amount was calculated from the following formula.
Migration component amount (% by weight) = (weight of sample 1−weight of sample 2) ÷ weight of sample 1 × 100

(7) Transferability evaluation adhesion rate of release film:
The sample film was cut to A4 size, and 75μm thick biaxially stretched PET film (Mitsubishi Chemical Polyester Film Co., Ltd .: Diafoil T100-75) was layered on the release surface and pressed for 2 hours under the conditions of temperature 60 ° C and pressure 1MPa. To do. A 75 μm-thick film pressed against this release surface is used as a migration evaluation film. Similarly, a 75 μm-thick biaxially stretched PET film (same as above) is pressed against an untreated PET film as a reference film. Adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation) is applied to the pressed surface of each film, then cut to a size of 50 mm × 300 mm, and the peel strength after standing for 1 hour at room temperature. It was measured. The peeling force was “Ezgraph” manufactured by Shimadzu Corporation, and 180 ° peeling was performed under the condition of a tensile speed of 0.3 (m / min).
Transferability evaluation adhesion rate (%) = (Peeling force of transferability evaluation film ÷ Peeling force of reference film) × 100
In a film having a high migration property, since a lot of silicone adheres to the pressed film, the peeling force of the adhesive tape is reduced, and the migration evaluation adhesion rate (%) is also lowered.

(8) Evaluation of release force (F) of release film:
After attaching one side of a double-sided adhesive tape (“No. 31B” manufactured by Nitto Denko) to the surface of the release layer of the sample film, the sample film was cut to a size of 50 mm × 300 mm and then peeled after being left at room temperature for 1 hour. taking measurement. 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 conditions of a tensile speed of 300 mm / min and further 10,000 mm / min. Judgment is based on the following criteria.

<Peeling force at 300 mm / min>
○: A range of 10 to 20 mN / cm.
X: Less than 10 mN / cm or more than 20 mN / cm.

<Comparison of peel force at 10,000 mm / min and peel force at 300 mm / min>
Judgment was made based on the value obtained by the following equation.
(10000 mm / min peeling force (mN / cm)) / (300 mm / min peeling force (mN / cm))
○: 2.5 or less.
X: Greater than 2.5.

(9) Mold release characteristics:
The release characteristics were evaluated from the situation when the release film was peeled off from the laminated film having the adhesive layer.
○: The release film peels cleanly, and the phenomenon that the adhesive adheres to the release layer is not observed.
(Triangle | delta): Although a release film peels, an adhesive adheres to a release layer when it peels at a quick speed.
X: Adhesive adheres to the release film and does not peel off well.

(10) Measurement of hardness of polyester film coat surface:
Using a dynamic ultra-micro altimeter (DUH-211) manufactured by Shimadzu Corporation on the surface layer of the polyester film, a triangular pyramid indenter (angle between ridges 115 °, Belkovic type), test force: 0.10 mN, load Holding speed: 0.0060 mN / sec. Load holding time: 2 sec. The Martens hardness was calculated from the indentation depth with respect to the test force. The number of measurements was 12, and the average value was taken.

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

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

Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

(12) MOR_C value measurement of polyester film by microwave molecular orientation meter:
The MOR_C value was determined from the transmission microwave intensity pattern using a microwave molecular orientation meter manufactured by Oji Scientific Instruments.

(13) MOR_C value measurement of polyester film by microwave molecular orientation meter:
The MOR_C value was determined from the transmission microwave intensity pattern using a microwave molecular orientation meter manufactured by Oji Scientific Instruments. Judgment is based on the following criteria.
○: The range is from 2.0 to 2.5.
Δ: The range is 1.5 to 1.9 or 2.6 to 3.0.
X: It is lower than 1.5% or higher than 3.0.

(14) Practical properties:
<Visual inspection under reflected light>
Taking the polarizing plate inspection into consideration, the width direction of the release film obtained by applying a release agent on the film and having a dryer temperature of 120 ° C. and a line speed of 30 m / min is parallel to the alignment axis of the polarizing film. As described above, the release film was closely adhered to the polarizing film through an adhesive to form a polarizing plate. The polarizing plate was visually observed under reflection of a fluorescent lamp, and the visual inspection property under reflected light was evaluated according to the following criteria. In the measurement, an A4 size sample was cut out.
"Criteria"
○: Good inspectability.
Δ: Inspection can be performed almost without any problem.
X: Inspectability is poor.
○ and △ are the levels where there is no problem in actual use.

<Visual inspection under crossed Nicols>
Taking the polarizing plate inspection into consideration, the width direction of the release film obtained by applying a release agent on the film and having a dryer temperature of 120 ° C. and a line speed of 30 m / min is parallel to the alignment axis of the polarizing film. As described above, the release film was adhered to the polarizing film through the pressure-sensitive adhesive to obtain a polarizing plate. Here, when the polarizing plate was prepared, black metal powder (foreign matter) having a size of 50 μm or more was mixed between the pressure-sensitive adhesive and the polarizing film so as to be 50 / m ² . A polarizing plate for inspection is superimposed on the polarizing plate release film mixed with the foreign matter thus obtained so that the orientation axis is orthogonal to the width direction of the release film, and white light is irradiated from the polarizing plate side. Then, it was visually observed from a polarizing plate for inspection, and whether or not a foreign matter mixed between the adhesive and the polarizing film was found under crossed Nicols was evaluated according to the following criteria. In the measurement, A4 size samples were cut out from a total of three locations in the center and both ends in the width direction of the obtained film.
"Criteria"
○: Good foreign body recognition.
Δ: Foreign matter can be recognized with relatively no problem.
X: Foreign matter recognition is poor.
○ and △ are the levels where there is no problem in actual use.
Among the above criteria, those above ○ are levels that can be used without any problem in actual use.

(15) Overall evaluation:
An evaluation is performed in consideration of film forming properties, productivity, inspection characteristics, etc. Judgment is based on the following criteria.
○: Even if it is produced, it can be supplied as a product.
Δ: Productivity is good and the frequency of defects in optical inspection is low.
X: Productivity is poor. There are many problems with optical inspection.

The polyester used in the examples and comparative examples was prepared as follows.
<Method for producing polyester (a)>
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, adding tetrabutoxy titanate as a catalyst to the reactor, setting the reaction start temperature to 150 ° C., and gradually increasing the reaction temperature as methanol is distilled off. It was 230 degreeC after 3 hours. After 4 hours, the transesterification reaction was substantially completed, and then a polycondensation reaction was performed for 4 hours.
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 the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.61 due to a change in the stirring power of the reaction vessel, and the polymer was discharged under nitrogen pressure to obtain a polyester (a) having an intrinsic viscosity of 0.61.

<Method for producing polyester (b)>
In the method for producing polyester (a), after adding ethyl acid phosphate, an ethylene glycol slurry of synthetic calcium carbonate particles having an average particle diameter of 0.8 μm was added so that the content of the particles with respect to polyester was 1% by weight. Obtained polyester (b) using the method similar to the manufacturing method of polyester (a). The obtained polyester (b) had an intrinsic viscosity of 0.60.

<Production of polyester (c)>
Starting from 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, magnesium acetate tetrahydrate is added as a catalyst to the reactor, the reaction start temperature is 150 ° C., and the reaction temperature is gradually increased as methanol is distilled off. The temperature was raised to 230 ° C. after 3 hours.
After 4 hours, the transesterification reaction was substantially terminated. Ethyl acid phosphate was added to the reaction mixture, which was then transferred to a polycondensation tank, and 0.04 part of antimony trioxide was added to carry out a polycondensation reaction for 4 hours. 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 the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.45 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure to obtain a polyester chip (c). The intrinsic viscosity of this polyester was 0.45.

<Manufacture of polyester (d)>
The intrinsic viscosity of this polyester chip was increased by a solid phase polycondensation method. After treatment in a preliminary crystallization tank at 170 ° C. in a nitrogen atmosphere for 0.5 hours, the moisture content becomes 0.005% at a temperature of 200 ° C. using a tower dryer that flows an inert gas. Until dried. Thereafter, it was sent to a solid phase polymerization tank and subjected to solid phase polymerization at 240 ° C. for 3 hours to obtain a polyester (d) having an intrinsic viscosity of 0.70.

<Manufacture of polyester (e)>
When producing the polyester (d), solid phase polymerization was performed in a solid phase polymerization tank for 5 hours to obtain a polyester (e) having an intrinsic viscosity of 0.80.

Example 1:
(Manufacture of polyester film)
As a raw material for the surface layer, 70% by weight of polyester (e) and 30% by weight of polyester (b) are mixed. As a raw material for the intermediate layer, 84% by weight of polyester (a) and 16% by weight of polyester (b) are mixed. Each was supplied to an extruder with a vent 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 unstretched sheet. Next, the film was stretched 2.8 times in the longitudinal direction at 100 ° C., then subjected to a preheating step in a tenter and subjected to a transverse stretching of 5.1 times at 120 ° C., followed by heat treatment at 220 ° C. for 10 seconds, 4% relaxation was added in the width direction at 180 ° C. to obtain a master roll having a width of 4000 mm. A slit was made from a position of 1400 mm from the end of the master roll, and the core roll was wound up 1000 m to obtain a polyester film. The total thickness of the obtained film was 50 μm (layer structure: surface layer 2.5 μm / intermediate layer 45 μm / surface layer 2.5 μm).

A release agent composed of release agent composition-A shown below was applied to the obtained polyester film by a reverse gravure coating method so that the coating amount (after drying) was 0.12 g / m ² , and a dryer temperature of 120 A roll-shaped release polyester film was obtained under the conditions of ° C and a line speed of 30 m / min. The obtained release polyester film had a release force of 14 mN / cm at a speed of 300 mm / min and a release force of 32 mN / cm at a speed of 10,000 mm / min.

<Releasing agent composition-A>
Curable silicone resin (LTC303E: manufactured by Toray Dow Corning)
20 parts addition type platinum catalyst (SRX212: manufactured by Toray Dow Corning) 0.2 part MEK / toluene / n-heptane mixed solvent (mixing ratio is 1: 1: 1)
Release agent composition-A transferable amount: 15% by weight

For the obtained polyester film, a deflector plate was prepared by the following method, and optical property inspection and peeling properties were evaluated. The obtained release film had good inspection by reflection and good recognition of foreign matter, and the polarizing plate was peeled off cleanly, and the phenomenon that the adhesive adhered to the release layer was not observed.

<Manufacture of polarizing plate with release film>
The acrylic adhesive shown below is applied to the polarizing plate so that the thickness after drying is 25 μm, and after passing through a 130 ° C. drying oven in 30 seconds, the release film is bonded, and the adhesive is interposed. Thus, a polarizing plate with a release film in which the release film and the polarizing film were adhered to each other was prepared. The laminating direction of the film was performed so that the width direction of the release film was parallel to the orientation axis of the polarizing film.
(Acrylic adhesive coating solution)
Acrylic adhesive (Olivein BPS429-4: manufactured by Toyo Ink) 100 parts Curing agent (BPS8515: manufactured by Toyo Ink) 3 parts MEK / toluene mixed solvent (mixing ratio is 1: 1) 50 parts

Examples 2-4:
In Example 1, the draw ratio at the time of manufacturing the polyester film, the coating thickness that changes the film thickness, the coating amount containing polyvinyl alcohol, the coating amount of the silicone release layer (after drying), and the amount of the migration component of the release agent composition A polyester film was obtained in the same manner as in Example 1 except that the above was changed. The obtained results are summarized in Table 1 below.

Comparative Example 1:
A polyester film was obtained in the same manner as in Example 1 except that the release agent composition was changed as follows. The results obtained are summarized in Table 2 below.
<Releasing agent composition-B>
Curing type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical Co., Ltd.) 20 parts Addition type platinum catalyst (PL-50T: manufactured by Shin-Etsu Chemical Co., Ltd.) 0.2 part MEK / toluene / n-heptane mixed solvent (mixing ratio is 1: 1: 1 )
Release agent composition-B transferable amount: 5% by weight

Comparative Example 2:
A polyester film was obtained in the same manner as in Example 1 except that the release agent composition was changed as follows. The results obtained are summarized in Table 2 below.
<Releasing agent composition-C>
Curable silicone resin (LTC303E: manufactured by Toray Dow Corning)
20 parts Silicone oil (KS-64-100cs) 0.18 parts Addition type platinum catalyst (SRX212: manufactured by Toray Dow Corning) 0.2 parts MEK / toluene / n-heptane mixed solvent (mixing ratio is 1: 1: 1) )
Release agent composition-C migration amount: 23% by weight

Comparative Example 3:
A polyester film was obtained in the same manner as in Example 1 except that <mold release composition-A> and the coating amount was changed to 0.25 g / m ² . The results obtained are summarized in Table 2 below.

Comparative Example 4:
A polyester film was obtained in the same manner as in Comparative Example 1 except that <Release Composition-C> in Comparative Example 1 and the coating amount was changed to 0.08 g / m ² . The results obtained are summarized in Table 2 below.

Comparative Examples 5 to 9:
In Example 1, it changes like the film thickness at the time of polyester film manufacture, It changes like Example 1 except changing the application quantity (after drying) of the coating layer containing polyvinyl alcohol, and a silicone type release layer. Manufactured to obtain a polyester film. The obtained results are summarized in Table 3 below.

Comparative Example 10:
A polyester film was obtained in the same manner as in Example 2 except that the release agent composition A was added with 3 parts of silicone oil (AL-1). The obtained results are summarized in Table 3 below.

Claims (5)

Silicone resin consisting of a polyester film having a release layer, which is used by pasting the release layer onto the adhesive layer of a baseless double-sided pressure-sensitive adhesive sheet, and the release layer has an alkenyl group as a functional group (A), containing an alkyl group-containing silicone resin (b), a component (c) for migration to the adhesive layer, and a platinum catalyst (d), and the content of the component (c) for migration is 5 to 20% by weight The release layer is a silicone-based release layer, the release layer has a low-speed peeling force in the range of 300 mm / min. In the range of 10 to 20 mN / cm, and the high-speed peeling force in the range of 10,000 mm / min. A release film characterized by being not more than 2.5 times the force. The release film according to claim 1, further comprising a coating layer obtained by coating a coating liquid containing polyvinyl alcohol between the polyester film and the silicone-based release layer. The release film according to claim 1 or 2, wherein the migration component in the silicone release layer contains a cyclic siloxane. The release film according to any one of claims 1 to 3, wherein the silicone release layer has a 115 ° triangular pyramid indenter and a Martens hardness of 400 N / mm ² or more at a test force of 0.10 mN. The release film according to any one of claims 1 to 4, wherein the polyester film has a MOR_C value of 1.5 to 3.0.