JP2012179888A - Polyester film for substrate-less double-sided adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive polyester film for a substrate-less double-sided adhesive sheet capable of suppressing peeling speed dependence to the minimum when the substrate-less double-sided adhesive sheet is used in optical applications, for example, a touch panel, a liquid crystal deflector, or a retardation plate, solving the problems of productivity, cost, or the like.SOLUTION: In the polyester film for the substrate-less double-sided adhesive sheet which is a polyester film with a silicone release layer containing a silicone resin having an alkenyl group and an alkyl group as functional groups and containing a transfer component of 5 to 20 wt.%, and a platinum catalyst, the low-speed peeling force in a 300 mm/min speed region of the release layer ranges 10-20 mN/cm and also the high-speed peeling force in a 10,000 mm/min speed region is 2.5 times or below the low-speed peeling force.

Description

  The present invention relates to a polyester film for a base-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 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, 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. 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.

JP 2009-220296 A JP 2003-231214 A JP 2002-361737 A Japanese Patent Application No. 2001-301024 Japanese Patent Application No. 2010-121101 JP 2009-220296 A JP 2010-13561 A Japanese Patent Laid-Open No. 10-158519

  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 an object of the present invention to provide an inexpensive polyester film for a double-sided pressure-sensitive adhesive sheet that can minimize productivity and solve problems such as productivity and cost.

  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 specific configuration, and has completed the present invention.

  That is, the gist of the present invention is a polyester film having a silicone release layer containing a silicone resin having an alkenyl group and an alkyl group as functional groups and containing 5 to 20% by weight of a migration component and a platinum catalyst. Yes, the release layer has a low-speed peel force in the range of 300 mm / min and a speed of 10-20 mN / cm, and a high-speed peel force in the range of 10,000 mm / min is 2.5 times the low-speed peel force. It exists in the polyester film for base-material-less double-sided adhesive sheets characterized by the following.

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

  The polyester film referred to in 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.
Examples of dicarboxylic acids include terephthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and diols include ethylene glycol and 1,4-butane. Examples include diol, diethylene glycol, triethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, polyethylene glycol and the like, and examples of hydroxycarboxylic acid include p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. be able to. Typical examples of such a polymer include polyethylene terephthalate and polyethylene-2,6-naphthalate.

  In the film of the present invention, it is preferable to blend particles mainly for the purpose of imparting slipperiness and preventing the occurrence of 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 to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-3 micrometers normally, Preferably it is the range of 0.1-2 micrometers. 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.

  Furthermore, the content of particles in the polyester 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 for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage for producing the polyester constituting each layer, but it is preferably added after completion of esterification or transesterification.

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

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

  Although the thickness of the polyester film in this invention will not be specifically limited if it is a range which can be formed into a film as a film, Usually, 10-350 micrometers, Preferably it is the range of 15-100 micrometers.

  Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all. 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 that 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 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.

  For the production of the polyester film of the present invention, a simultaneous biaxial stretching method can also be employed. 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 90 to 140 ° C., preferably 80 to 110 ° C., and the stretching ratio is as follows. Is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in terms of area magnification. 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 to 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 treatment on 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 type of release layer curable silicone resin to be formed on the outermost layer of one of the polyester films obtained in the present invention is any of addition type, condensation type, ultraviolet curable type, electron beam curable type, solventless type, etc. The reaction type can also be used.

  Examples of the silicone resin having an alkenyl group and an alkyl group as functional groups used in the present invention include the following. 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 / methylhexenyl blocked with dimethylhexenylsiloxy group blocked at both ends of the molecular chain Siloxane copolymers (95 mol% of dimethylsiloxane units and 5 mol% of methylhexenylsiloxane units) can be mentioned. Genpolysiloxanes include trimethylsiloxy group-capped methylhydrogen polysiloxane with both molecular chains, trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer with both molecular chains, and dimethylhydrogensiloxy group-capped methylhydro with molecular chains. Genpolysiloxane, dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer having both molecular chain ends.

In the present invention, silicone oil may be added in order to achieve migration. The silicone oil is a silicone oil called a straight silicone oil or a 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.
These silicone oils are preferably contained in the silicone resin in an amount of 0.1 to 5.0% by weight as a migration component. Both straight silicone oil and modified silicone oil are non-reactive, non-functional oils.

  The migration component contained in the silicone resin used in the present invention is in the range of 5 to 20% by weight, preferably 10 to 13% by weight. If the content of the transition component is lower than 5%, the speed dependency becomes high, and if it exceeds 20% by weight, the curability is remarkably lowered and the adhesion is also deteriorated.

  In the present invention, Nitto Denko Corporation No. The residual adhesion rate with 31B tape is preferably 65% to 90%, more 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.

  Specific examples of the silicone resin coating agent include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X manufactured by Shin-Etsu Chemical Co., Ltd. -62-2461, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210, manufactured by Dow Corning Asia Co., Ltd. YSR-3022, TPR-6700, TPR-, manufactured by Toshiba Silicone Co., Ltd. 6720, TPR-6721, Toray Dow Corning Co., Ltd. LTC300B, LTC303E, LTC310, LTC314, SRX357, BY24-749, SD7333, BY24-179, SP7015, SP7259, SD7220, SD7226, SD7229, and the like. Further, a release control agent may be used in combination to adjust the release property of the release layer. Further, as described above, a silane compound having an amino group may be added to 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 application amount of the release layer in the present invention is usually in the range of 0.01 to 1 g / m ² .

  In the present invention, 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 may be subjected to corona treatment, plasma treatment, etc. A surface treatment may be applied.

  In the polyester film in the present invention, a platinum-based catalyst that promotes an addition-type reaction is used to make the release layer clean and strong. 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.

  In addition, 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, and preferably 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol and phenylbuty It is a compound selected from the group consisting of nor.

  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 specific 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. Is preferably changed according to the desired peeling force, and 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.

  About the value of the peeling force of the polyester film in this invention, the low speed peeling force in a 300 mm / min speed area is the range of 10-20 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 range in consideration of 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.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measurement method and evaluation method used in the present invention are as follows.

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

(2) Measurement of amount of migrating component To 15 g of silicone resin diluted with toluene to a solid content concentration of 4% by weight, 0.02% by weight of platinum catalyst is added and 0.004 g is stirred, and then a Teflon (registered trademark) sheet is used. Place in the created box and heat cure at 150 ° 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

(3) Transferability Evaluation Adhesion Rate of Release Film Sample film was cut to A4 size, and 75 μm thick biaxially stretched PET film (Mitsubishi Chemical Polyester Film Co., Ltd .: Diafoil T100-75) was layered on the release surface. Press for 2 hours under conditions of a temperature of 60 ° C. and a pressure of 1 MPa. 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, a large amount of silicone adheres to the pressed film, so that the peeling force of the pressure-sensitive adhesive tape is reduced, and the migration evaluation adhesion rate (%) is also reduced.

(4) Evaluation of peel force (F) of release film Affixed with one side of double-sided adhesive tape (Nitto Denko "No. 31B") on the release layer surface of the sample film, then cut to a size of 50mm x 300mm 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 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>
○: Range of 10 to 20 mN / cm ×: Less than 10 mN / cm or greater 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 ×: More than 2.5

(5) 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. Δ: The release film peels off, but the adhesive adheres to the release layer when peeled at a high speed. Adhesive adheres to the release film and does not peel off well.

(6) Comprehensive evaluation An evaluation that takes into consideration all the film-forming properties, productivity, and inspection characteristics. Judgment is based on the following criteria.
○: Even if it is produced, it can be sufficiently supplied as a product. Δ: Productivity is good and the frequency of defects is low. ×: Productivity is poor. Many troubles occur.

Example 1
<Manufacture of polyester film>
The polyester described above is used as a raw material, supplied to an extruder with a vent, melt-extruded at 290 ° C, and then cooled and solidified on a cooling roll set at a surface temperature of 40 ° C using an electrostatic application adhesion method. An amorphous film having a thickness of about 550 μm was obtained.
This film was stretched 3.7 times in the longitudinal direction at 85 ° C., stretched 3.9 times in the transverse direction at 100 ° C., and heat treated at 210 ° C. to obtain a biaxially stretched polyester film having a thickness of 38 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 the dryer temperature was 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 parts 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 polarizing plate was prepared by the following method, and the peeling characteristics were evaluated. The obtained release film 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, it manufactured like Example 1 except changing the coating amount (after drying) of the release agent at the time of polyester film manufacture, and obtained the polyester film. The obtained results are summarized in Table 1 below.

Example 5:
In Example 2, it manufactured like Example 2 except having apply | coated what added 3 parts of silicone oil (AL-1) to mold release composition-A, and obtained the polyester film. 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.
<Releasing agent composition-B>
Curable 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 migration 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:
In Example 1, it was manufactured 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 to obtain a polyester film. The results obtained are summarized in Table 2 below.

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

  The polyester film of the present invention can be suitably used as a release polyester film having good productivity and low release rate dependency in the field of substrate-less double-sided pressure-sensitive adhesive sheets in optical applications where demand is great.

Claims (1)

A polyester film having a silicone-based release layer containing a silicone resin having an alkenyl group and an alkyl group as functional groups and containing 5 to 20% by weight of a migration component and a platinum-based catalyst, and 300 mm of the release layer The low-speed peeling force in the range of 10 / min / min is in the range of 10 to 20 mN / cm, and the high-speed peeling force in the range of 10,000 mm / min is 2.5 times or less of the low-speed peeling force. Polyester film for substrate-free double-sided PSA sheet.