KR20190076955A - Release film - Google Patents

Abstract

A release film comprising a release layer comprising a cured silicone resin and a cured product formed of inert particles on at least one side of a polyester film and having a peel strength between the release layer and the acrylic adhesive measured by a predetermined method of 50 g / A release film of 25 mm or less.

Description

Release film

More particularly, the present invention relates to a release film which is easy to adjust the peeling force and is stable in releasing property even in a state where it is stuck to a pressure-sensitive adhesive over a long period of time.

BACKGROUND ART [0002] A release film made of a polyester film as a base material is used for various purposes in terms of mechanical strength, heat resistance, thermal dimensional stability, chemical resistance, and economical efficiency. For example, optical clear adhesives (PDP) constituent members, and organic electroluminescence (organic EL) constituent members used for manufacturing LCD components such as polarizer / retarder used for liquid crystal display (LCD) and liquid crystal display (LCD) For industrial use such as labeling, adhesive tape, veneer, transfer tape and the like for use in the manufacture of articles, for adhesive films for medical applications such as poultices / adhesives, for ceramic sheets, for polyvinyl chloride sheets, .

In the production of the LCD component member, a product distribution is constituted by a method of feeding a polarizing plate with a polarizing plate maker cut to a panel maker and a method called a roll-to-panel method in which a polarizing plate maker and a panel maker feed a polarizing plate in a roll state . Here, the release film is coated on its surface to protect the polarizing plate, for example, until the polarizing plate is mounted on the member in the manufacturing process. In recent years, the period from the manufacture of the polarizing plate to the peeling of the release film in order to attach the polarizing plate to the member has been prolonged due to the relationship of inventory adjustment of the polarizing plate and the like. For this reason, it is demanded that the release film is stable in releasing property even when the release film is stuck to the pressure-sensitive adhesive over a long period of time (Patent Document 1).

Japanese Patent Application Laid-Open No. 6-246880

However, in the conventional releasing film, since the reaction between the silicone resin contained in the releasing layer of the releasing film and the pressure-sensitive adhesive proceeds at the surface of the releasing layer in interlocking with the pressure-sensitive adhesive over a long period of time, So that it becomes difficult to peel off.

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a releasing mold (releasing force) which is stable in releasing force (peeling force) To provide a film.

The inventor of the present invention has conducted intensive studies in view of the above circumstances and found that the use of a release film having a specific structure can improve the stability with time of peeling force in the state of being stuck to the pressure sensitive adhesive from the prior art , Thereby completing the present invention.

That is, the gist of the present invention is that the polyester film has a release layer comprising a cured silicone resin and a cured product formed of inert particles on at least one side of the polyester film and also the release layer and the acrylic pressure- Is present in a release film having a strength of 50 g / 25 mm or more and 150 g / 25 mm or less (first preferred embodiment).

<Measurement method>

An acrylic pressure-sensitive adhesive composed of the following pressure-sensitive adhesive composition was applied to the release layer surface of the release film so that the coating amount (before drying) became 2 mil and heat-treated at 150 占 폚 for 3 minutes. The pressure-sensitive adhesive surface after the heat treatment is joined to an untreated polyethylene terephthalate biaxially stretched film (thickness 188 占 퐉) and a rubber roller having a load of 2 kg to prepare a release film comprising a pressure-sensitive adhesive.

Then, the releasing force of the releasing film provided with the sticking adhesive is measured at room temperature for 1 hour. The peeling force is 180 deg. Peeled under a condition of a tensile speed of 300 mm / min.

&Lt; Composition of pressure-

100 parts by weight of AT352 (manufactured by Saiden Chemical Industry Co., Ltd.)

Curing agent: 0.25 parts by weight of AL (manufactured by Saiden Chemical Industry Co., Ltd.)

Additive: 0.25 parts by weight of X-301-375SK (manufactured by Saiden Chemical Industry Co., Ltd.)

Additive: 0.4 parts by weight of X-301-352S (manufactured by Saiden Chemical Industry Co., Ltd.)

40 parts by weight of toluene

Further, the gist of the present invention is that a polyester film has a release layer made of a cured silicone resin and a cured product formed on at least one side of the polyester film, and also has an occupation of inert particles on the surface of the release layer using a scanning electron microscope (Second preferred embodiment) in which the area ratio is 4% or more and 12% or less.

According to the above constitution of the present invention, it is possible to obtain a release film in which the releasability with time is not greatly changed even in a situation where the adhesive is stuck to the pressure-sensitive adhesive over a long period of time, And is suitable for the production of various optical members for polarizing plate production and touch panel production.

1 is a SEM image of a surface of a release layer of a release film of Example 1. Fig.
2 is a SEM image of the surface of the release layer of the release film of Example 9. Fig.
3 is an SEM image of the surface of the release layer of the release film of Comparative Example 3. Fig.

Best Mode for Carrying Out the Invention Hereinafter, the present invention, its constituent elements, and preferred embodiments for carrying out the present invention will be described in detail.

(Polyester film)

The polyester in the polyester film used for the release film is preferably obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol, and even if it is a polyester comprising one kind of aromatic dicarboxylic acid and one kind of aliphatic glycol Or a copolymerized polyester obtained by copolymerizing one or more other components. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid. Examples of the aliphatic glycol include ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol and the like. Representative polyesters include polyethylene terephthalate and the like. On the other hand, examples of the dicarboxylic acid used as the component of the copolymerizable polyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid and the like. Examples of the glycol component include ethylene glycol, di Ethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like. Oxycarboxylic acids such as p-oxybenzoic acid may also be used. It may also be a polyester obtained by copolymerizing other acid components or glycol components and may contain various functionalizing components such as conventionally known colorants (dyes / pigments), ultraviolet absorbers, antioxidants, antistatic agents, conductive agents, heat stabilizers, Or an additive may be contained.

In the polyester film constituting the release film, in order to reduce the amount of the oligomer contained in the film precipitated or crystallized on the surface of the film due to thermal history during film processing or the like, It is also possible to use a polyester in which the amount of oligomers is reduced. As a method for reducing the amount of oligomers in the polyester, for example, a solid phase polymerization method or the like can be used.

The polyester film constituting the release film may contain particles for the main purpose of imparting lubricity, securing the running property of the film in each step, and preventing scratches. The type of the particles to be incorporated is not particularly limited as long as the particles are capable of imparting lubricity, and specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, calcium phosphate, calcium fluoride, Calcium, lithium fluoride, zeolite, magnesium phosphate, kaolin, talc, aluminum oxide, alumina, titanium oxide, molybdenum sulfide and the like. Heat resistant organic particles described in Japanese Patent Publication No. 59-5216 and Japanese Patent Laid-Open No. 59-217755 may also be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, and benzoguanamine resins. It is also possible to use precipitation particles in which a part of a metal compound such as a catalyst is precipitated or finely dispersed in a polyester production process.

On the other hand, the shape of particles to be used is not particularly limited, and any of spherical, lumpy, rod-shaped, and flattened phases may be used. The hardness, specific gravity, color, and the like are not particularly limited. These particles may be used in combination of two or more as necessary.

The particle size and content of the particles are selected depending on the application and purpose of the film, but the average particle diameter of the particles when used for optical purposes is usually in the range of 0.01 to 5 탆, preferably 0.01 to 2 탆. When the average particle diameter is less than 0.01 탆, the particles easily aggregate and the dispersibility may be insufficient. On the other hand, when the average particle diameter exceeds 5 탆, the surface roughness of the film is excessively coarse, There is a case where a problem arises in the case of coating (setting).

When used for optical purposes, the content of the particles is usually 0.001 to 5% by weight, preferably 0.005 to 3% by weight. If the content of the particles is less than 0.001% by weight, the film may not be sufficiently lubricated. If the content is more than 5% by weight, transparency of the film may be insufficient.

In the case where there is no or little particles, transparency of the film is improved and a good film is obtained. However, since handling may become difficult due to insufficient slip property, for example, knurling or inserting particles into the coating layer .

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

In addition, a method of blending a polyester raw material with a slurry of particles dispersed in ethylene glycol, water or the like using a kneading extruder equipped with a vent, a method of blending the dried particles and a polyester raw material by using a kneading extruder, Lt; / RTI &gt;

The polyester film constituting the release film may have a single layer structure or a laminated structure of two or more layers and is not particularly limited.

The release film may contain an ultraviolet absorber in the polyester film in order to improve the weather resistance of the film. The ultraviolet absorber is not particularly limited as long as it is a compound having an ultraviolet absorptive ability and can withstand the heat added in the production process of the polyester film.

As the ultraviolet absorber, there are an organic ultraviolet absorber and an inorganic ultraviolet absorber, but from the viewpoint of transparency, an organic ultraviolet absorber is preferable. Examples of the organic ultraviolet absorber include, but are not limited to, cyclic imino ester, benzotriazole, benzophenone, and the like. From the viewpoint of durability, the cyclic imino ester type and benzotriazole type are more preferable. It is also possible to use two or more ultraviolet absorbers in combination.

The thickness of the polyester film constituting the release film is not particularly limited as long as the film can be formed into a film, but is usually 400 占 퐉 or less, preferably 5 to 250 占 퐉, more preferably 12 to 200 占 퐉.

The transparency of the polyester film is not particularly limited, but in the case of optical applications requiring transparency, the haze is preferably 1.8% or less, more preferably 1.2% or less.

The total light transmittance of the polyester film is not particularly limited, but is preferably 80% or more, and more preferably 85% or more, for optical applications requiring transparency.

The production example of the polyester film constituting the release film will be described concretely. However, the following production examples are not limited in any way, and a commonly known film formation method of a polyester film can be adopted. That is, a method of obtaining an unstretched sheet by cooling and solidifying a molten sheet extruded from a die with a cooling roll using the above-described polyester raw material. In this case, it is preferable to enhance the adhesion between the sheet and the rotating cooling drum in order to improve the planarity of the sheet, and the electrostatic adhesion method and / or the liquid application adhesion method are preferably employed. Subsequently, the obtained unoriented sheet is stretched in the biaxial direction. In this case, first, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120 占 폚, preferably 80 to 110 占 폚, and the stretching magnification is usually 2.5 to 7.0 times, preferably 3.0 to 6.0 times. Then, the stretching is carried out in a direction orthogonal to the stretching direction of the first stretch. In this case, the stretching temperature is usually 70 to 170 占 폚, and the stretch ratio is usually 3.0 to 7.0 times, preferably 3.5 to 6.0 times. Subsequently, heat treatment is carried out at a temperature of 180 to 270 ° C under relaxation or under 30% relaxation to obtain a biaxially oriented film. In the above stretching, a method of performing stretching in one direction in two or more steps may be adopted. In this case, it is preferable that the stretching magnifications in the two directions finally become the above ranges.

For the production of the polyester film, simultaneous biaxial stretching may be employed. The simultaneous biaxial stretching method is a method in which the above-mentioned unstretched sheet is stretched in the machine direction and the width direction at the same time in a state in which the temperature is controlled at 70 to 120 ° C, preferably 80 to 110 ° C, The magnification is preferably 4 to 50 times, more preferably 7 to 35 times, and still more preferably 10 to 25 times. Subsequently, heat treatment is carried out at a temperature of 170 to 250 ° C under relaxation or under a relaxation of 30% or less to obtain a stretched orientation film. As the simultaneous biaxial stretching apparatus employing the above-described stretching method, a conventionally known stretching method such as a screw method, a pantograph method, and a linear driving method can be employed.

(Functional layer)

In the release film of the present invention, a functional layer may be interposed between the polyester film and the release layer. Examples of the functional layer include an adhesive layer, an antistatic layer, a conductive layer, an antifouling layer, a bleed-out component sealing layer, a refractive index adjusting layer, a light transmittance improving layer, a light absorbing layer, , A pressure-sensitive adhesive layer, and a layer obtained by combining these functionalities. Further, the functional layer may be a single layer or may have two or more layers. The functional layer may be provided by an inline coating process for treating the film surface during the stretching process of the polyester film, or an off-line coating may be employed for coating the film on a once-produced film outside the system.

The in-line coating is not limited to the following examples. For example, in the case of sequential biaxial stretching, the coating treatment can be carried out particularly after stretching in the flow direction, that is, before stretching in the width direction. When the functional layer is provided on the polyester film by the in-line coating, the functional layer can be applied at the same time as the film formation, and the functional layer can be treated at a high temperature, thereby making it possible to produce a film suitable as a polyester film.

When a functional layer is provided by in-line coating, it is preferable to prepare a laminated polyester film by applying a series of compounds to be described later as an aqueous solution or an aqueous dispersion and applying a coating liquid onto the polyester film. In addition, the coating liquid may contain a small amount of an organic solvent for the purpose of improving the dispersibility in water, improving the film formability, and the like within the range not impairing the gist of the present invention. The organic solvent may be used alone or in combination of two or more.

The organic solvent content of the coating liquid is preferably 10% by weight or less, and more preferably 5% by weight or less. Specific examples of the organic solvent include aliphatic or alicyclic alcohols such as n-butyl alcohol, n-propyl alcohol, isopropyl alcohol, ethyl alcohol and methyl alcohol; Glycols such as propylene glycol, ethylene glycol and diethylene glycol; glycol derivatives such as n-butyl cellosolve, ethyl cellosolve, methyl cellosolve and propylene glycol monomethyl ether; Ethers such as dioxane and tetrahydrofuran; Esters such as ethyl acetate and amyl acetate; Ketones such as methyl ethyl ketone and acetone; And amides such as N-methylpyrrolidone.

In addition, regardless of the off-line coating or in-line coating, active energy ray irradiation such as heat treatment and ultraviolet ray irradiation may be used in combination as occasion demands.

Examples of the method for forming the functional layer include a coating method such as gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, , Impregnation coating, kiss coating, spray coating, calender coating, extrusion coating, and the like.

Examples of the polymer used for forming the functional layer include a vinyl resin such as a polyester resin, a polyurethane resin, an acrylic resin and a polyvinyl alcohol, an epoxy resin, a melamine resin, a polyether resin, an amide resin, an aramid resin, Imide resin, fluorine resin, and silicone resin.

These skeleton structures may have a substantially complex structure by copolymerization or the like. Examples of the polymer having a complex structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, Vinyl resin graft polyurethane and the like.

As the crosslinking agent used for forming the functional layer, various known resins can be used. For example, a crosslinking agent such as a melamine compound, a guanamine compound, an alkylamide compound, a polyamide compound, a glyoxal compound, a carbodiimide compound, , An oxazoline compound, an aziridine compound, an isocyanate compound, a silane coupling agent, a dialcohol aluminate coupling agent, a dialdehyde compound, a zirconylate coupling agent, a peroxide, a thermally or photoreactive vinyl compound, .

The functional layer may contain particles for the purpose of improving the sliding property. There is no particular limitation on the average particle size. However, when used for optical applications, for example, it is preferably in the range of 1.0 탆 or less, more preferably 0.5 탆 or less, particularly preferably 0.2 탆 or less Range. Specific examples of the particles include inert inorganic particles such as silica, alumina, calcium carbonate and titanium dioxide, and fine particles obtained from polystyrene-based resins, polyacrylic resins and polyvinyl resins, or organic particles typified by such crosslinked particles.

In addition, the functional layer may contain a surfactant, a defoaming agent, a coating improver, a releasing agent, a thickener, an organic lubricant, an antistatic agent, a conductive agent, a refractive index adjuster, a light absorber such as ultraviolet ray, an antioxidant, a foaming agent, .

Analysis of the components in the functional layer can be performed by, for example, analysis of TOF-SIMS, ESCA, fluorescent X-ray and the like.

The thickness of the functional layer provided on the polyester film in the present invention is usually 0.01 to 3 g / m ² , preferably 0.02 to 1 g / m ² , more preferably 0.03 to 0.3 g / m &lt; ² &gt;. When the thickness of the functional layer 0.01g / m ² is less than the functional layer there is a possibility that sufficient performance is not obtained, exceeds 3g / m ² in the adhesion of the release layer, or deterioration in the appearance and transparency, It is liable to cause an increase in cost due to blocking of the film and lowering of the line speed. The coating amount can be determined by calculation from the weight of the applied liquid (before drying), the concentration of nonvolatile matter in the coating liquid, the coating width, the draw ratio, the line speed, and the like.

The polyester film may be subjected to various surface treatments separately from the functional layer. Conventionally known techniques can be used for various surface treatments. Examples of the surface treatment include surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet ray treatment, high frequency treatment, microwave treatment, glow discharge treatment, active plasma treatment, and laser treatment.

(Releasing layer)

The release layer constituting the release film will be described below.

From the viewpoint of obtaining good releasability, it is important that the release film of the present invention contains a curable silicone resin and inert particles. The constituent components of the release layer other than the curable silicone resin and the inert particles are not particularly limited as far as they have good releasability at the time of peeling from the pressure-sensitive adhesive layer. Or a modified silicone type by graft polymerization with an organic resin such as an urethane resin, an epoxy resin or an alkyd resin may be used. When the pressure-sensitive adhesive layer is a silicone pressure-sensitive adhesive or the like, it preferably contains a fluorosilicone resin or the like.

As the type of the curable silicone resin, any type of curing reaction such as addition type or condensation type can be used. It is also possible to use any kind of curing reaction type such as thermosetting type or ultraviolet ray curing type. A plurality of types of curable silicone resins may be used in combination. There is no particular limitation on the coating form of the curing-type silicone resin at the time of forming the releasing layer, and it may be any of a form dissolved in an organic solvent, a form of an aqueous emulsion, and a form of a non-solvent.

As a specific embodiment in which a plurality of curing-type silicone resins are used in combination, for example, a curing-type silicone resin containing an alkenyl group and a curing-type silicone resin containing SiH groups are used in combination as described below, It is possible to suppress the change of the peeling force with the elapse of time.

The peeling force of the releasing film can be adjusted to an appropriate range by using a coating liquid containing a curing-type silicone resin containing inactive particles and a curing-type silicone resin-containing coating liquid containing no inert particles as a coating liquid for use in the releasing layer There is a case that the peeling force can be suppressed from changing with time.

There is no limitation on the kind of the curable silicone resin, but from the viewpoint of the mold releasing property excellent in peelability and the like, the use of the curable silicone resin containing an alkenyl group is preferable in the present invention. The curable silicone resin containing an alkenyl group may be a diorganopolysiloxane represented by the following general formula (1).

R _(3-a) X _a SiO- (RXSiO) _m- (R ₂ SiO) _n -SiX _a R _(3-a) (One)

In the general formula (1), R is a monovalent hydrocarbon group having 1 to 10 carbon atoms, and X is an organic group containing an alkenyl group. a is an integer of 0 to 3, preferably 1, and m is an integer of 0 or more. When a = 0, m is 2 or more, and m and n are integers satisfying 100? m + , And the above formula includes a random copolymer and does not mean a block copolymer.

R is a monovalent hydrocarbon group of 1 to 10 carbon atoms, and specific examples thereof include alkyl groups such as methyl, ethyl, propyl and butyl groups, cycloalkyl groups such as cyclohexyl, allyl groups such as phenyl and tolyl, However, methyl group and phenyl group are particularly preferable. X is an organic group containing an alkenyl group and preferably has 2 to 10 carbon atoms, and specifically, a vinyl group, an allyl group, a hexenyl group, an octenyl group, an acryloylpropyl group, an acryloylmethyl group, Cyclohexenylethyl group, and vinyloxypropyl group. Of these, a vinyl group and a hexenyl group are particularly preferable. Specifically, for example, dimethylsiloxane-methylhexenylsiloxane blocked with trimethylsiloxy groups at both ends of the molecular chain (dimethylsiloxane unit: 96 mol%, methylhexenylsiloxane unit: 4 mol%), molecular chain-terminated dimethylvinylsiloxy group-blocked dimethyl (97 mol% of dimethylsiloxane unit and 3 mol% of methylhexenylsiloxane unit), dimethylhexenylsiloxane-blocked dimethylsiloxane-methylhexenylsiloxane copolymer having both ends of the molecular chain (dimethylsiloxane unit 95 Mol%, and methylhexenylsiloxane unit: 5 mol%).

It is preferable that SiH groups are contained in the curable silicone resin in order to react with the alkenyl groups contained in the curable silicone resin to form a stronger silicone release layer. The SiH group-containing polyorganosiloxane is, for example, an organohydrogenpolysiloxane having at least two, and preferably three or more, hydrogen atoms bonded to silicon atoms in a molecule, and may be linear, branched, cyclic And the like, and compounds represented by the following general formula (2) can be used, but the present invention is not limited thereto.

^{_{H b R 1 (3-b}} ) SiO- (HR 1 SiO) x - (R 1 2 SiO) y -SiR 1 (3-b) H b ... (2)

In the general formula (2), R ¹ is a monovalent hydrocarbon group containing no aliphatic unsaturated bond having 1 to 6 carbon atoms. b is an integer of 0 to 3, and x and y are integers. Specifically, examples include a molecular chain endblocked trimethylsiloxy group-blocked methylhydrogenpolysiloxane, a molecular chain endblocked trimethylsiloxy group-blocked dimethylsiloxane-methylhydrogensiloxane copolymer, a molecular chain-terminated dimethylhydrogensiloxy group-blocked methylhydrogenpolysiloxane , Dimethylhydrogensiloxy blocked dimethylsiloxane-methylhydrogensiloxane copolymer at both ends of the molecular chain.

Specific examples of the curable silicone resin used in the present invention are KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X (trade name, manufactured by Shin-Etsu Chemical Co., 62-2422, X-62-2461, X-62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A / B , X-62-7052, X-62-7028A / B, X-62-7619, X-62-7213, X-41-3035; YSR-3022, TPR-6700, TPR-6720, TPR-6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605 of Momentive Performance Materials. Dow Corning's SRX357, SRX211, SD7220, SD7292, LTC750A, LTC760A, LTC303E, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205 , DKQ3-210; DEHESIVE 636, 919, 920, 921, 924, 929 and the like of the DEHESIVE series manufactured by Asahi Chemical Industry Co., Ltd. can be exemplified.

Among the compositions constituting the release layer, it is preferable to use a platinum-based catalyst for promoting the addition reaction in order to secure strength. Examples of the component include platinum compounds such as chloroplatinic acid, an alcohol solution of chloroplatinic acid, a complex of chloroplatinic acid with olefin, complex of chloroplatinic acid with alkenylsiloxane, platinum black, platinum supported silica, and platinum supported activated carbon. The platinum-group catalyst content in the composition constituting the release layer is preferably 0.3 to 3.0% by weight, more preferably 0.5 to 2.0% by weight. When the content of the platinum-based catalyst in the composition constituting the release layer is lower than 0.3% by weight, problems such as peeling force and curing reaction in the release layer become insufficient, which may cause problems such as surface shape deterioration. On the other hand, when the content of the platinum-based catalyst in the composition constituting the release layer is more than 3.0% by weight, the reactivity is increased and problems may arise in processes such as generation of gel foreign matter.

In addition, acetyl alcohol may be added as an addition reaction inhibitor in some cases because the reaction of the addition type is highly reactive. The component is an organic compound having a carbon-carbon triple bond and a hydroxyl group, but preferably 3-methyl-1-butyn-3-ol, 3,5-dimethyl- Is preferably a compound selected from the group consisting of

Among the compositions constituting the release layer, it is possible to use a catalyst other than the platinum-based catalyst in combination for the purpose of accelerating the hydrolysis and condensation reaction. Specific examples of the catalyst include organic acids such as acetic acid, butyric acid, maleic acid, and citric acid; Inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid; Basic compounds such as triethylamine; Tetrabutyl titanate, dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin dioctate, dibutyl tin diolate, diphenyl tin diacetate, dibutyl tin oxide, dibutyl tin dimethoxide, dibutyl Organometallic salts such as bis (triethoxysiloxy) tin and dibutyltin benzylmalate; KF, NH ₄ F, and the like. These catalysts may be used alone or in combination of two or more. Among them, organometallic salts are particularly preferable in that the coating film durability is improved.

In the second preferred embodiment of the present invention, in order to adjust the releasing force of the releasing layer to a desired releasing force and stably maintain a desired releasing force even when sticking to the pressure-sensitive adhesive over a long period of time, The occupation area ratio of the inert particles when the surface of the release layer is observed using a scanning electron microscope (SEM) containing the resin and the inert particles under the following conditions is 4% or more and 12% or less do.

"Scanning electron microscope observation conditions"

• Apparatus: S-3400N (manufactured by Hitachi, Ltd.)

· Observation mode: secondary electron (observation) mode

Acceleration voltage: 15 kV

· Probe current: 30

· Object aperture: 3

· Operating distance (WD): 10 mm

· Magnification: 20000 times

Since the occupied area ratio of the inert particles is 4% or more like the release film of the present invention, the inert particles can inhibit or suppress the reaction of the surface of the release layer, and it is possible to stably maintain the desired peeling force. The occupied area ratio of the inert particles is preferably 5% or more, and more preferably 7% or more.

On the other hand, the upper limit of the occupied area ratio of the inert particles is 12% or less. When the occupied area ratio of the inert particles exceeds 12%, the peeling force becomes very large at the time immediately after the release film is formed, making it difficult to separate the release film from the pressure-sensitive adhesive. The peel strength is also very large.

The occupied area ratio of the inert particles in the present invention indicates the ratio of the area in which the inert particles can exist in the vicinity of the surface of the release layer. The occupied area ratio of the inert particles is controlled by the coating method and the curing conditions at the time of forming the releasing layer. Inert particles are formed on the surface of the release layer by forming the release layer in a coating method or a curing condition to be described later, so that the occupied area ratio of the inert particles can be satisfied within a prescribed range.

Therefore, the occupied area ratio of the inert particles is not determined solely by the content of the inert particles in the coating liquid for the release layer. Even if the release layer contains a large amount of inert particles, inert particles do not appear on the surface of the release layer. If the occupied area ratio of the inert particles is less than 4%, the inert particles will inhibit or suppress the reaction with the pressure- The peeling force at the time of peeling becomes large. Even if only a small amount of inert particles are contained in the release layer, inert particles appear on the surface of the release layer. If the occupation area ratio of the inert particles is within the specified range, the inert particles inhibit the reaction with the pressure- Or suppressing an increase in peel strength with time.

Further, as long as it is measured by the above-mentioned rule, it is not necessary to target only the inert particles contained in the release layer. For example, in the case where inert particles are contained in the surface layer of the polyester film, or when the inert particles are contained in the optional functional layer, it is not necessary to identify the inert particles contained in these layers .

As the inert particles used for the release layer, any material may be used, but specifically, particles that can be used for imparting lubricity to the above-mentioned polyester film can be similarly used. Among them, inorganic particles are preferable, and silica particles are more preferable from the viewpoint of versatility. Specifically, BY24-312, BY24-4980, Nissan Chemical Industries, Ltd., "Snowtex" manufactured by Toray Dow Corning Co., Ltd., and "OSCAL" manufactured by Nikkiso Catalysts Co., Ltd., and the like are exemplified.

From the viewpoint of the compatibility with the silicone resin in the release layer and the distribution of the silica particles in the release layer, the surface of the silica particles is more preferably a compound having the structure of the general formula (3), and all the trimethylsilyl Is particularly preferable.

Si-O-Si- (R?) _C (R?) _D (R?) _E ... (3)

(In the general formula (3), R ?, R? And R? Are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group, and c, d and e are integers and c + d + e = 3.

The average particle diameter of the inert particles used for the release layer is usually in the range of 0.01 to 5 占 퐉, preferably 0.01 to 2 占 퐉. When the average particle size of the inert particles is within the specified range, the occupying area ratio of the surface of the release layer is satisfied, so that the peeling force can be adjusted to an appropriate range or a change in peeling force with time can be suppressed.

The content of the inert particles used in the release layer is usually in the range of 1 to 50% by weight, preferably 2 to 40% by weight, and more preferably 3 to 30% by weight. When the content of the inert particles is within the specified range, the occupied area ratio of the surface of the release layer is satisfied, so that the peeling force can be adjusted to an appropriate range, or the change in peeling force with time can be suppressed.

In addition to the inert particles, a release force adjusting agent may be used in combination. When the peeling force is increased, usually a heavy peeling agent such as organopolysiloxane or a silicon species having a large peeling force is added in an appropriate amount in a composition constituting the releasing layer. Specific examples of the heavy-weight rejuvenating agent include KS-3800 and X-92-183 manufactured by Shinetsu Kagaku Kogyo K.K.

When the peeling force is to be reduced, a low molecular siloxane compound is selected in various ways, and an appropriate content is added to the release layer so that the siloxane migration component exerts the release performance. Examples of the low-molecular siloxane compound include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane. Further, other compounds of the low-molecular siloxane compound include a molecular chain end-capped trimethylsiloxy-blocked dimethylsiloxane oligomer; A dimethylhydroxysiloxane-blocked dimethylsiloxane oligomer having both ends of a molecular chain, and the like. These compounds may be used in combination as required. These low-molecular-weight siloxane compounds contain 0.1 to 15% by weight, preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, of the silicone resin in the silicone resin. When the content of the low-molecular siloxane compound is less than 0.1% by weight, the releasability is hardly exhibited because the amount of the transitional component is small. On the other hand, if the content of the low-molecular siloxane is larger than 15% by weight, the transitional component precipitates excessively, and thus tends to cause process contamination.

To the release layer constituting the release film, an organosilicon compound may be used in combination to improve the adhesion of the release layer and the polyester film to each other, and it is preferable to use an organosilicon compound represented by the following general formula (4) .

Si (X) _f (Y) _g (R ² ) _h ... (4)

(The formula (4), X is an epoxy group, a mercapto group, a (meth) acryloyl group, an alkenyl group, an organic group having at least one selected from a haloalkyl group and an amino group, Y is a hydrolyzable group, R ² is F is an integer of 1 or 2, g is an integer of 2 or 3, h is an integer of 0 or 1, and f + g + h = 4.

As the organosilicon compound represented by the general formula (4), there can be used two or three hydrolyzable groups Y capable of forming siloxane bonds by hydrolysis and condensation reaction.

In the general formula (4), examples of the hydrolyzable group Y include the following. A methoxy group, an ethoxy group, a butoxy group, an isopropenoxy group, an acetoxy group, a butaneoxime group and an amino group. These hydrolyzable groups may be used alone or in combination. When a methoxy group or an ethoxy group is applied, it is particularly preferable because good storage stability can be imparted to the coating material and also suitable hydrolysis property can be obtained.

In the general formula (4), the monovalent hydrocarbon group R ² has 1 to 10 carbon atoms, and particularly preferably a methyl group, an ethyl group or a propyl group.

Specific examples of the organosilicon compound contained in the release layer include vinyltrimethoxysilane,? -Glycidoxypropyltrimethoxysilane,? -Glycidoxypropylmethyldiethoxysilane,? - (3,4-epoxycyclo Methacryloxypropyltrimethoxysilane,? -Acryloxypropyltrimethoxysilane,? -Aminopropyltriethoxysilane,? - aminopropyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane, Hexyltrimethoxysilane, p-styryltrimethoxysilane, trifluoropropyltrimethoxysilane,? -Glycidoxypropyltriethoxysilane,? -Glycidoxypropylmethyldiisopropenoxysilane, etc. Can be exemplified.

The content of the organosilicon compound in the release layer is more preferably 0.5 to 5.0 parts by weight, more preferably 0.5 to 2.0 parts by weight, based on 100 parts by weight of the curable silicone resin. If the amount is less than 0.5 part by weight, it may be difficult to secure the desired adhesiveness. On the other hand, when the amount exceeds 5.0 parts by weight, adhesion to the counterpart resin layer is excessively strong, Which may cause problems such as inability to peel off easily.

The releasing layer may contain additives such as a surfactant, a defoaming agent, a coating improver, a thickener, an inorganic organic particle, an organic lubricant, an antistatic agent, a conductive agent, an ultraviolet absorber, A foaming agent, a dye, a pigment, and the like.

The release layer may be formed by coating the coating liquid on a film, and may be provided by in-line coating in a film production process, or may be applied by a so-called off-line coating on a once-fabricated film.

As a method for controlling the occupation area ratio, there is a method of adjusting the coating method of the release layer and the curing conditions.

As a method of preparing the releasing layer, there can be mentioned a reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze coating, impregnation coating, kiss coating, spray coating, Extrusion coating, and other known coating methods described above. As for the coating method, there is an example described in "Coating Method" (published by Maki Bookstore, Hara Saki, published in 1979).

The curing conditions for forming the releasing layer are not particularly limited. When the releasing layer is provided by off-line coating, the releasing layer is usually cured at 80 DEG C or more for 10 seconds or more, preferably 100 to 200 DEG C for 3 to 40 Second, more preferably at 120 to 180 ° C for 3 to 40 seconds.

Examples of a heat source used when the release layer is cured include thermal roll contact, contact with a heat medium such as air, infrared heating, microwave heating, and the like. Among them, by using infrared heating capable of solvent removal and curing in a short time, the inert particles are likely to appear on the surface of the release film, and the occupation area ratio of the inert particles within a predetermined range is obtained.

If necessary, active energy ray irradiation such as heat treatment and ultraviolet irradiation may be used in combination. As an energy source for curing by active energy ray irradiation, a well-known apparatus and an energy source can be used.

The coated amount of the releasing layer (after drying) is usually in the range of 0.005 to 5 g / m ² , preferably 0.005 to 1 g / m ² , more preferably 0.005 to 0.1 g / m ² from the viewpoint of coatability. When the amount of coating (after drying) is less than 0.005 g / m ² , stability is less than that of the coating, and it may become difficult to obtain a uniform coating film. On the other hand, when the thickness of the release layer itself is more than 5 g / m ² , the coating film adhesion, curability, etc. of the release layer itself may be deteriorated.

With respect to the release film thus obtained, it is preferable that the peeling force between the release layer and the acrylic pressure-sensitive adhesive layer measured by the following method is 50 g / 25 mm or more. The releasing film of the present invention exhibits peeling stability particularly at a time when the releasing force is 50 g / 25 mm or more.

The releasing film of the present invention can contain the releasing force between the releasing layer and the acrylic pressure-sensitive adhesive layer within a predetermined range by adjusting the occupied area ratio of the inert particles contained in the releasing layer. However, the means for the peeling force is not limited to the method for adjusting the occupied area ratio of the inert particles contained in the releasing layer.

<Measurement method>

An acrylic pressure-sensitive adhesive composed of the following pressure-sensitive adhesive composition was applied to the release layer surface of the release film so that the coating amount (before drying) became 2 mil and heat-treated at 150 占 폚 for 3 minutes. The pressure-sensitive adhesive surface after the heat treatment is joined to an untreated polyethylene terephthalate biaxially stretched film (thickness 188 占 퐉) and a rubber roller having a load of 2 kg to prepare a release film comprising a pressure-sensitive adhesive.

Then, the releasing force of the releasing film provided with the sticking adhesive is measured for 1 hour at room temperature. The peeling force is 180 deg. Peeled under a condition of a tensile speed of 300 mm / min.

&Lt; Composition of pressure-

Topic: 100 parts by weight of AT352 (manufactured by Saiden Chemical Industry Co., Ltd.)

Curing agent: 0.25 parts by weight of AL (manufactured by Saiden Chemical Industry Co., Ltd.)

Additive: 0.25 parts by weight of X-301-375SK (manufactured by Saiden Chemical Industry Co., Ltd.)

Additive: 0.4 parts by weight of X-301-352S (manufactured by Saiden Chemical Industry Co., Ltd.)

40 parts by weight of toluene

Further, if it has the same adhesive property as that of the above-mentioned pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition may be replaced with another pressure-sensitive adhesive composition.

On the other hand, the upper limit of the peeling force between the release layer and the acrylic pressure-sensitive adhesive layer is preferably 150 g / 25 mm or less. The releasing film of the present invention can exert peeling stability particularly at a time when the peeling force is 150 g / 25 mm or less, and can stably maintain the peeling force in carrying out transportation and stocking for a long period of time .

In the first preferred embodiment of the present invention, the releasing force between the releasing layer and the acrylic pressure-sensitive adhesive layer is 50 g / 25 mm or more and 150 g / 25 mm or less.

With respect to the peel strength with time, the release film of the present invention preferably has a peel force of 150 g / 25 mm or less after leaving for two months in a constant temperature and humidity atmosphere at 23 캜 and 50% RH, more preferably 100 g / Do. When the peeling force is 150 g / 25 mm or less, the peeling force can be stably maintained in transportation and stocking for a long period of time.

Further, from the viewpoint of the change of the peeling force with time, the releasing force after the film is left for 3 months in a constant temperature and humidity chamber at 23 캜 and 50% RH atmosphere is more preferably 100 g / 25 mm or less, and particularly preferably 85 g / 25 mm or less Do. Here, the method of measuring the peeling force is the same as described above.

The release film of the present invention can be used as a release film comprising a pressure-sensitive adhesive having an acrylic pressure-sensitive adhesive layer on a release layer side of a release film.

Further, the release film of the present invention can be suitably used as a protective film for optical members such as, for example, a liquid crystal polarizing plate and a touch panel.

The acrylic pressure sensitive adhesive applied to the release film of the present invention is a resin containing an acrylic monomer as a constituent component. The acrylic resin may be of only one type, or two or more types. The acrylic monomers may be either one kind alone or two or more kinds.

The acrylic resin preferably contains a (meth) acrylic acid alkyl ester as a monomer component constituting the resin. Examples of (meth) acrylic acid alkyl esters include hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) (Meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl and (meth) acrylic acid alkyl esters having an alkyl group having 6 to 14 carbon atoms such as n-tetradecyl (meth) acrylate. The (meth) acrylic acid alkyl ester may be one kind or two or more kinds.

In addition, a polyfunctional monomer may be contained in the constituent components of the acrylic resin, for example, from the viewpoint that a crosslinked structure can be introduced into the acrylic resin and an appropriate cohesive force can be obtained.

Specific examples include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, (Meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (metha) acrylate, divinylbenzene and N, N'-methylenebisacrylamide. . The multifunctional monomers may be one kind or two or more kinds.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, comparative examples and production examples, but the present invention is not limited to the following examples, comparative examples and production examples unless the gist thereof is exceeded. The evaluating method and the sample treatment method in the examples, comparative examples and production examples are as follows.

(1) Intrinsic viscosity of polyester (intrinsic viscosity)

1 g of polyester was precisely weighed and dissolved in 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) and measured at 30 캜.

(2) Average particle diameter (d50: 占 퐉)

The value of 50% of the total (based on weight) in the equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution measuring apparatus (SA-CP3 type (Shimazu Seisakusho) Co., Ltd.) was taken as the average particle diameter.

(3) Evaluation of peeling strength with time of releasing film

An acrylic pressure-sensitive adhesive composed of the following pressure-sensitive adhesive composition was applied to the releasing layer side of the release film using a baker-type applicator so that the coating amount (before drying) became 2 mil and heat-treated at 150 캜 for 3 minutes by a hot air circulation path. The pressure-sensitive adhesive surface after the heat treatment was joined to an untreated polyethylene terephthalate biaxially stretched film (thickness 188 占 퐉) and a rubber roller having a load of 2 kg to prepare a release film comprising a pressure-sensitive adhesive.

Then, the releasing film provided with the adhesive to be bonded was left under each settling condition, cut into a size of 50 mm x 300 mm, and peel force after standing at room temperature for 1 hour was measured. The peel strength was measured by using a tensile tester ("Tesco Model", made by Tesco Co., Ltd., type) at 180 ° peeling under the condition of a tensile speed of 300 mm / min and evaluation of the peel strength . In this evaluation, the portion of the maximum peel force value recorded at the start of peeling in the peeling force profile was evaluated.

&Quot; Adhesive composition &quot;

Topic: 100 parts by weight of AT352 (manufactured by Saiden Chemical Industry Co., Ltd.)

Curing agent: 0.25 parts by weight of AL (manufactured by Saiden Chemical Industry Co., Ltd.)

Additive: 0.25 parts by weight of X-301-375SK (manufactured by Saiden Chemical Industry Co., Ltd.)

Additive: 0.4 parts by weight of X-301-352S (manufactured by Saiden Chemical Industry Co., Ltd.)

40 parts by weight of toluene

&Quot; Conditions for leaving a release film having a pressure-sensitive adhesive &quot;

Condition 1: Immediately after forming the release film

Condition 2: Leave the release film in a constant temperature and humidity chamber at 23 占 폚 and 50% RH for 1 month

Condition 3: The release film is left in a constant temperature and humidity chamber at 23 DEG C and 50% RH atmosphere for 2 months

Condition 4: Leave the release film in a thermostatic chamber at 23 ° C and 50% RH for 3 months

&Quot; Criteria for evaluation of peel strength &

A: The peeling force under Condition 4 is 85 g / 25 mm or less

B: Peeling force under Condition 4 exceeding 85 g / 25 mm and not more than 100 g / 25 mm

C: Peeling force in Condition 3 exceeding 100 g / 25 mm and not more than 150 g / 25 mm

D: Peel force in condition 3 exceeds 150g / 25mm

(4) Evaluation of occupancy area ratio of silica particles

The surface of the release layer of the prepared release film was observed with a scanning electron microscope (S-3400N, manufactured by Hitachi, Ltd.), and the obtained SEM image of 5 탆 was subjected to two-dimensional image analysis software (manufactured by Mitani Co., , WinRoof), and then the occupied area ratio of the silica particles in the SEM image of 5 탆 square was obtained.

"Scanning electron microscope observation conditions"

· Device used: S-3400N

· Observation mode: secondary electron (observation) mode

Acceleration voltage: 15 kV

· Probe current: 30

· Object aperture: 3

· Operating distance (WD): 10 mm

· Magnification: 20000 times

The raw materials of the polyester film used in the following production examples are as follows.

&Lt; Production method of polyester (I)

100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol were used as starting materials and 0.09 part by weight of magnesium acetate quaternary salt as a catalyst was taken in the reactor to set the reaction initiation temperature to 150 캜 and the reaction temperature was gradually raised And after 3 hours, the temperature was set to 230 deg. After 4 hours, the transesterification reaction was substantially terminated. To this reaction mixture, 0.04 part by weight of ethyl acid phosphate was added and then 0.04 part by weight of antimony trioxide was added, and the resultant was subjected to 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 gradually decreased from the atmospheric pressure and finally reached 0.3 mmHg. After the initiation of the reaction, the reaction was stopped at the point when the intrinsic viscosity reached 0.63 dL / g due to the change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure. The intrinsic viscosity of the obtained polyester (I) was 0.63 dL / g.

&Lt; Production method of polyester (II)

After adding 0.04 part by weight of ethyl acetate phosphate in the production method of polyester (I), 0.3 part by weight of silica particles having an average particle size of 1.6 占 퐉 and 0.04 part by weight of antimony trioxide dispersed in ethylene glycol were added to obtain an ultimate viscosity of 0.65 dL (II) was obtained in the same manner as in the production of polyester (I), except that the polycondensation reaction was stopped at a time point corresponding to the amount of the polyester (I) / g. The obtained polyester (II) had an intrinsic viscosity of 0.65 dL / g.

In addition, as the composition of the functional layer formed on the surface of the polyester film, the following was used.

(A1) a copolymerized polyester resin having an acid component having a condensed polycyclic aromatic structure and an aliphatic acid component: an aqueous dispersion of a polyester resin copolymerized in the following composition

Monomer Composition: (Acid component) 2,6-Naphthalene dicarboxylic acid / Sebacic acid / Sodium 5-sulfoisophthalate // (Diol component) Ethylene glycol / Hexanediol / Diethylene glycol = 37/11/3 // 27 / 17/5 (mol%)

(A2) Acrylic resin: An aqueous dispersion of an acrylic resin polymerized in the following composition

(Emulsifier: anionic surfactant) of ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylol acrylamide / acrylic acid = 65/21/10/2/2

(B1) 3-glycidoxypropyltrimethoxysilane

(B2) Epoxy compound: polyglycerol polyglycidyl ether

(B3) hexamethoxymethylol melamine

[Example 1]

The polyester (I) was used as a raw material for the outermost layer (surface layer), and the polyester (I) was used as a raw material for the intermediate layer in two extruders Extruded in a layer configuration of two kinds of three layers (surface layer / intermediate layer / surface layer) on a cooling roll set at 40 占 폚 after melting each at 285 占 폚, New sheets were obtained. Subsequently, the film was stretched 3.4 times in the flow direction (longitudinal direction) at a film temperature of 85 ° C using a roll speeder, and then drawn in a tenter to stretch 4.3 times in the transverse direction at 120 ° C. , A laminated polyester film having a thickness of 38 mu m (surface layer: 5 mu m, intermediate layer: 28 mu m) was obtained.

The obtained laminated polyester film was applied by a reverse gravure coating method so that the coating liquid composed of the releasing agent composition A was applied in an amount of 0.13 g / m ² (after drying) by off-line, and a maximum temperature of 166 캜 , And dried at a line speed of 50 m / min to obtain a release film.

Table 2 shows the evaluation results of the occupied area ratio and the peel strength with time of the silica particles distributed on the surface of the release layer of the obtained release film. An SEM image of the surface of the release layer of the release film is shown in Fig.

<Releasing Agent Composition A>

(i) Addition type cured silicone resin (X62-5039, manufactured by Shin-Etsu Chemical Co., Ltd.): 15 parts by weight

(A mixture of a vinyl group-containing curable silicone resin and a SiH group-containing curable silicone resin)

(ii) 5 parts by weight of silica particle-containing addition type cured silicone resin (BY24-312, manufactured by Toray-Dow Corning Co., Ltd.)

(A mixture of a curing-type silicone resin containing an alkenyl group and a curing-type silicone resin containing SiH groups, which contains silica particles)

(iii) 0.5 part by weight of an addition type platinum catalyst (CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.)

(iv) a mixed solvent of methyl ethyl ketone / toluene (mixing ratio of 1: 1)

[Example 2] - [Example 8]

The unstretched sheet was stretched 3.4 times in the longitudinal direction in the same manner as in Example 1, and Coating Liquids 1 to 7 having the compositions shown in the following Table 1 were coated on one side of the film so as to have a predetermined amount (after drying) The laminate was stretched 4.3 times in the transverse direction at 120 ° C and heat-treated at 225 ° C to obtain a laminated polyester film having a functional layer having a thickness of 38 μm (surface layer: 5 μm, intermediate layer: 28 μm).

The obtained laminated polyester film was provided with a release layer in the same manner as in Example 1 on the functional layer to obtain a release film. Table 2 shows the evaluation results of the occupied area ratio and the peel strength with time of the silica particles distributed on the surface of the release layer of the obtained release film.

[Example 9]

The laminated polyester film obtained in Example 1 was applied by a reverse gravure coating method so that the coating liquid composed of the release agent composition A was applied in an amount of 0.13 g / m ² (after drying) by offline, After the heat treatment, a release film was obtained.

Table 2 shows the evaluation results of the occupied area ratio and the peel strength with time of the silica particles distributed on the surface of the release layer of the obtained release film. An SEM image of the surface of the release layer of the release film is shown in Fig.

[Comparative Example 1]

The polyester (I) was fed to two extruders as raw materials for the outermost layer (surface layer) and the intermediate layer, respectively, melted at 285 캜, and then cooled on a cooling roll set at 40 캜, Extruded and cooled and solidified to obtain an unoriented sheet. Subsequently, the film was stretched 3.4 times in the longitudinal direction at a film temperature of 85 占 폚 using a roll speed racer, and then drawn by a tenter. The stretched film was stretched 4.3 times in the transverse direction at 120 占 폚 and heat-treated at 225 占 폚. To obtain a polyester film.

The obtained polyester film was applied by a reverse gravure coating method so that the coating liquid composed of the releasing agent composition B containing no inert particles was applied at a coating amount (after drying) of 0.13 g / m ² by off-line, After heat treatment for 10 seconds, a release film was obtained. Table 2 shows the evaluation results of the occupied area ratio and the peel strength with time of the silica particles distributed on the surface of the release layer of the obtained release film.

&Lt; Release agent composition B &

(i) Addition type cured silicone resin (X62-5039, manufactured by Shin-Etsu Chemical Co., Ltd.): 15 parts by weight

(A mixture of a vinyl group-containing curable silicone resin and a SiH group-containing curable silicone resin)

(ii) 5 parts by weight of an organopolysiloxane resin (KS-3800, manufactured by Shin-Etsu Chemical Co., Ltd.)

(iii) 0.5 part by weight of an addition type platinum catalyst (CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.)

(iv) a mixed solvent of methyl ethyl ketone / toluene (mixing ratio of 1: 1)

[Comparative Example 2]

The unstretched sheet was stretched 3.4 times in the longitudinal direction in the same manner as in Comparative Example 1, and the coating liquid 1 having the coating composition shown in Table 1 below was applied on one side of the film so that the amount of coating (after drying) , Stretched 4.3 times in the transverse direction at 120 캜, and heat-treated at 225 캜 to obtain a laminated polyester film having a functional layer having a thickness of 38 탆 (surface layer 5 탆, intermediate layer 28 탆).

The obtained laminated polyester film was provided with a release layer on the functional layer in the same manner as in Comparative Example 1 to obtain a release film. Table 2 shows the evaluation results of the occupied area ratio and the peel strength with time of the silica particles distributed on the surface of the release layer of the obtained release film.

[Comparative Example 3]

The coating liquid consisting of the release agent composition C was applied by offline to a coating amount (after drying) of 0.10 g / m ² and heat-treated at 130 캜 for 10 seconds to obtain a release film. Table 3 shows the evaluation results of the occupied area ratio and the peel strength with time of the silica particles distributed on the surface of the release layer of the obtained release film. An SEM image of the surface of the release layer of the release film is shown in Fig.

&Lt; Release agent composition C &

(i) Silica particle-containing addition type cured silicone resin (BY24-312, manufactured by Dow Corning Toray Co., Ltd.): 5.3 parts by weight

(A mixture of a curing-type silicone resin containing an alkenyl group and a curing-type silicone resin containing SiH groups, which contains silica particles)

(ii) 0.11 part by weight of an addition type platinum catalyst (CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.)

(iii) a mixed solvent of methyl ethyl ketone / toluene (70:30)

The releasing films of Examples 1 to 8 retained the peeling force without increasing the peeling force too much after 3 months had passed from the sticking agent, and were practically useful releasing films. The release film of Example 9 was a release film that could be practically used because it did not cause serious problems that caused problems even after 2 months had passed since the adhesive was applied to the pressure-sensitive adhesive.

On the other hand, in the release films of Comparative Examples 1 and 2, the peeling force became large after a lapse of one month after being stuck to the pressure-sensitive adhesive, and there was a problem that problems could arise in a case such as transportation and inventory for a long period of time. In addition, the releasing film of Comparative Example 3 had a large peeling force with the pressure-sensitive adhesive immediately after the preparation, and had a problem that problems could occur as a releasing film.

INDUSTRIAL APPLICABILITY The present invention can be suitably used for the production of optical members such as, for example, for the production of liquid crystal polarizers and touch panels.

Claims (8)

A releasing layer comprising a cured silicone resin and a cured product formed of inert particles on at least one side of the polyester film and having a peeling force between the releasing layer and the acrylic adhesive measured by the following method is 50 g / 150 g / 25 mm or less.
<Measurement method>
An acrylic pressure-sensitive adhesive composed of the following pressure-sensitive adhesive composition was applied to the release layer surface of the release film so that the coating amount (before drying) became 2 mil and heat-treated at 150 占 폚 for 3 minutes. The pressure-sensitive adhesive surface after the heat treatment is joined to an untreated polyethylene terephthalate biaxially stretched film (thickness 188 占 퐉) and a rubber roller having a load of 2 kg to prepare a release film comprising a pressure-sensitive adhesive.
Then, the releasing force of the releasing film provided with the sticking adhesive is measured after standing at room temperature for 1 hour. The peeling force is 180 deg. Peeled under a condition of a tensile speed of 300 mm / min.
&Lt; Composition of pressure-
Topic: 100 parts by weight of AT352 (manufactured by Saiden Chemical Industry Co., Ltd.)
Curing agent: 0.25 parts by weight of AL (manufactured by Saiden Chemical Industry Co., Ltd.)
Additive: 0.25 parts by weight of X-301-375SK (manufactured by Saiden Chemical Industry Co., Ltd.)
Additive: 0.4 parts by weight of X-301-352S (manufactured by Saiden Chemical Industry Co., Ltd.)
40 parts by weight of toluene A release layer comprising a cured silicone resin and a cured product formed from inert particles on at least one side of the polyester film and having an occupied area ratio of inert particles on the surface of the release layer using a scanning electron microscope is not less than 4% and not more than 12% , Release film. 3. The method according to claim 1 or 2,
Wherein the curable silicone resin comprises a curable silicone resin containing an alkenyl group. 4. The method according to any one of claims 1 to 3,
Wherein the curable silicone resin comprises a curable silicone resin containing SiH groups. 5. The method according to any one of claims 1 to 4,
Wherein the cured product comprises a platinum catalyst. 6. The method according to any one of claims 1 to 5,
A release film comprising a functional layer interposed between a polyester film and a release layer. A release film comprising a pressure-sensitive adhesive having an acrylic pressure-sensitive adhesive layer on the mold release layer side of the release film according to any one of claims 1 to 6. 7. The method according to any one of claims 1 to 6,
A release film used as a protective film of an optical member.

Images