JP6010381B2 - Release film - Google Patents

Description

  The present invention relates to a release film for a transparent optical adhesive sheet (OCA: Optical Clear Adhesive).

  In recent years, release films based on polyester films have been used as carrier films and separators for optically transparent adhesive sheets (OCA) used for bonding members such as touch panels.

  OCA used for bonding members such as a touch panel is, for example, by applying a resin composition to be an OCA adhesive layer on a release film as a carrier film, and bonding a release film as a separator thereon, It is manufactured by preparing a release film (carrier film: heavy release) / OCA adhesive layer / release film (separator: light release) composite and punching the composite into a required size. Furthermore, in practice, since it is difficult to peel off the separator as it is punched, the separator is peeled once after punching, and the separator having a larger area than the punched OCA adhesive layer is pasted again for the next step. Is done.

  In use, the separator-side release film is peeled off from the above-mentioned composite, and is attached to the bonding surface of a member such as a touch panel, and then the carrier film-side release film is peeled off and attached to a counterpart member such as a liquid crystal display device. Used together.

International Publication No. 2009/063847 Pamphlet

  The OCA after punching is handled by a single wafer. However, in the above-described process, since there is a process of reattaching the separator, the peeling charge generated in the process remains in the OCA. There is a problem that handling properties are lowered such as when OCA sticks to each other when handling with a single wafer and a conveyance error occurs.

  Furthermore, regarding the release film mainly as a carrier film, the present inventors, in OCA using a conventional release film as a carrier film, caused an increase in the haze of the OCA adhesive layer after peeling of the carrier film, resulting in an optical such as a touch panel. We found a new problem that makes product quality inspection difficult. That is, for example, when manufacturing optical products such as touch panels, the OCA separator is peeled off and attached to the member, then the carrier film is peeled off, and then the optical product is inspected before attaching the counterpart member. However, in such a case, if the haze of the OCA adhesive layer becomes high, quality inspection becomes difficult.

  The inventors of the present invention have noted that the cause of this increase in haze is that the surface roughness of the release film surface of the release film is transferred to the OCA adhesive layer. As a countermeasure, a design that smoothes the surface of the release layer is conceivable, but on the other hand, if it is too smooth, the slipping property and the handling property are deteriorated, and scratches are easily generated during transportation. In addition, there is a problem that it is difficult to inspect in the quality inspection before peeling the carrier film, or that the scratch causes a defect in the OCA adhesive layer, making it difficult to inspect the quality after peeling the separator or carrier film.

  Therefore, the present invention is a release film used for OCA, which can suppress the release charge of OCA, can suppress the haze increase of the OCA adhesive layer, and has excellent handling properties. The object is to provide a film.

The present invention adopts the following configuration in order to solve the above problems.
1. A release film having an antistatic layer and a release layer in this order on at least one surface of a base film, wherein the 10-point average roughness Rz on the release layer surface is 650 nm or more and 1600 nm or less, and the release film A release film for a transparent adhesive sheet for optical use, having a surface specific resistance value of 10 ⁶ Ω / □ or more and 10 ¹² Ω / □ or less on the surface of the layer.
2. 2. The release film for an optical transparent adhesive sheet according to the above 1, wherein the antistatic layer is a silicon oxide film formed by hydrolysis and / or condensation reaction of a tetrafunctional silicon compound.
3. The release film for an optical transparent pressure-sensitive adhesive sheet according to the above 1 or 2, wherein the release force on the surface of the release layer is 19.5 mN / 25 mm or more and 680 mN / 25 mm or less when measured at room temperature.
4). The release film for optically transparent adhesive sheets for optical recording according to any one of 1 to 3, wherein the 10-point average roughness Rz on the surface of the release layer is 650 nm or more and 1200 nm or less.
5. In the release layer surface is more than the height 0.2μm projections 100 to 800 pieces / mm ^2, more height 0.6μm projections is 10 to 130 pieces / mm ^2, more height 1.2μm 5. The release film for a transparent adhesive sheet for optics according to 4, wherein the number of protrusions is 10 pieces / mm ² or less.
6). The laminated body which has a release film of any one of said 1-5 on both surfaces of an adhesion layer.

  ADVANTAGE OF THE INVENTION According to this invention, the release charge for OCA which can suppress peeling charge of OCA, can suppress the haze rise of an OCA adhesion layer, and was excellent in the handleability can be provided. Such a release film for OCA can be suitably used as an OCA carrier film and a separator.

<Release film>
The release film of the present invention has a base film and an antistatic layer and a release layer in this order on at least one surface thereof.

(Surface roughness)
In the release film of the present invention, the 10-point average roughness Rz on the release layer surface is 650 nm or more and 1600 nm or less. When Rz on the surface of the release layer is in the above numerical range, the haze increase of the OCA pressure-sensitive adhesive layer after peeling the release film can be suppressed. Furthermore, the handleability of the release film is excellent. If Rz is higher than the above range, the haze of the OCA pressure-sensitive adhesive layer after peeling the release film will increase. From such a viewpoint, Rz is preferably 1200 nm or less, more preferably 1150 nm or less, and still more preferably 1000 nm or less. On the other hand, if Rz is lower than the above range, the slipping property of the film is deteriorated, the handling property of the release film is lowered in the process of coating the release layer or OCA, and scratches are likely to occur. . Furthermore, the release films tend to stick to each other, and peeling charge tends to occur easily. From such a viewpoint, Rz is preferably 650 nm or more, more preferably 700 nm or more, and further preferably 730 nm or more.

  Such 10-point average roughness Rz can be achieved by changing the aspect of the particles added to the base film to the preferred aspect described below. In addition, when adopting a method of cooling the molten polyester resin on the rotary cooling drum during the production of the base film, a release layer is provided on the film surface on the side in contact with the rotary cooling drum surface, as described above. The preferable range of Rz can be achieved more easily, which is preferable.

(Protrusion distribution)
Release film of the present invention, the release layer surface, or the height 0.2μm projections was 100 to 800 pieces / mm ^2, more than the height 0.6μm projections at 10 to 130 pieces / mm ² And the number of protrusions having a height of 1.2 μm or more is preferably 10 pieces / mm ² or less. By setting it as such an aspect, the improvement effect of the transcription | transfer suppression of the uneven | corrugated shape to an OCA adhesion layer can be made high, ensuring the outstanding slipperiness, and the improvement effect of the haze rise suppression of an OCA adhesion layer is made high. it can. When both are too low, the improvement effect of slipperiness is low, and when both are too high, the improvement effect of haze rise suppression is low. From such a viewpoint, the protrusion having a height of 0.2 μm or more is more preferably 150 to 700 pieces / mm ² , further preferably 200 to 600 pieces / mm ² , and the protrusion having a height of 0.6 μm or more is more preferably 20 to 100 / mm ^2, more preferably from 30 to 70 pieces / mm ^2, the height 1.2μm or more projections is more preferably 8 / mm ² or less, more preferably 5 pieces / mm ² or less.

  Such protrusion height can be achieved by changing the aspect of the particles added to the base film to the preferred aspect described below. In addition, when adopting a method of cooling the molten polyester resin on the rotary cooling drum during the production of the base film, if a release layer is provided on the film surface that is in contact with the rotary cooling drum surface, It is easy to obtain a surface that satisfies this aspect of the height distribution of protrusions, which is preferable.

(Surface specific resistance)
In the release film of the present invention, the surface specific resistance value on the surface of the release layer is 10 ⁶ Ω / □ or more and 10 ¹² Ω / □ or less. By setting it as such a range, peeling electrification can be suppressed. When the surface specific resistance value is too high, the peeling charge is not sufficiently suppressed, and the handling property such as OCA transportability is deteriorated. From such a viewpoint, the surface resistivity is preferably 10 ¹¹ Ω / □ or less, more preferably 10 ¹⁰ Ω / □ or less. On the other hand, a low surface specific resistance value is preferable for suppressing peeling electrification, but if a lower surface specific resistance value is to be obtained, for example, a thermosetting type or UV curable release layer may inhibit the hardening. In some cases, it may be difficult to form a release layer, and it may be difficult to obtain suitable release performance. Moreover, it may become excessive quality and cost may become high. From this viewpoint, it is preferably 10 ⁸ Ω / □ or more, more preferably 10 ⁹ Ω / □ or more.

Such a surface specific resistance value may be achieved by providing an arbitrary antistatic layer between the base film and the release layer so as to have the above-described characteristics. For example, the antistatic property can be increased by using an antistatic agent having a high antistatic property, increasing the thickness of the antistatic layer, or reducing the thickness of the release layer. Preferably, an embodiment as described later may be adopted.
Hereafter, each structural component which comprises the release film of this invention is demonstrated.

<Base film>
(polyester)
The base film in the present invention is not particularly limited, but a thermoplastic resin film made of a thermoplastic resin having flexibility and heat resistance is preferably used. Preferred examples of the polymer constituting the thermoplastic resin film include polyesters such as polyethylene terephthalate and polyethylene naphthalate, aliphatic polyamides, aromatic polyamides, polyethylene, and polypropylene. Among them, polyester is preferable because it is excellent in heat resistance, rigidity, quality, and the like and is suitable for OCA.

  The polyester in the present invention comprises a dicarboxylic acid component as the first component and a glycol component as the second component. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid and the like. In particular, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferable from the viewpoint of excellent mechanical properties of the base film. Examples of the glycol component include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, cyclohexanedimethanol, polyethylene glycol, and the like. . In particular, ethylene glycol is preferable from the viewpoint of excellent rigidity of the base film.

  The polyester may be a copolyester obtained by copolymerizing at least one of the dicarboxylic acid components or at least one of the glycol components as a third component. As the third component, a copolymer component different from the dicarboxylic acid component selected as the first component or the glycol component selected as the second component can be selected. Further, the third component may include a trifunctional or higher polyvalent carboxylic acid component or a polyol component. In this case, the copolymerization amount is within a range in which the obtained polyester is substantially linear (for example, 5 mol). % Or less, more preferably 3 mol% or less, and particularly preferably 1 mol% or less). As the polyester in the present invention as described above, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferable, and polyethylene terephthalate is particularly preferable.

Such a polyester can be produced by a conventional method. When the intrinsic viscosity of the polyester (intrichlorophenol at 35 ° C.) is 0.45 (unit: dl / g) or more, the rigidity of the film is high. It is preferable because of its excellent mechanical properties.
The base film in the present invention may be a single layer or a laminated structure.

(Surface roughness)
In the present invention, in order to prevent haze increase of the OCA adhesive layer, as described above, the 10-point average roughness Rz on the surface of the release layer needs to be 650 nm or more and 1600 nm or less. For this purpose, the 10-point average roughness Rz on the substrate film surface (the surface on the side where the antistatic layer and the release layer are formed and before the formation of the antistatic layer and the release layer) is The release layer is preferably 600 nm or more, more preferably 650 nm or more, preferably 1250 nm or less, more preferably 1200 nm or less, and the 10-point average roughness Rz of the base film is within the above numerical range. It becomes easy to adjust Rz on the release film surface (release layer surface) after formation, and the haze of OCA after peeling the release film can be suppressed.

In order to make 10-point average roughness Rz of a base film into the said numerical range, it can adjust by adding the particle | grains of an inorganic substance or organic substance to a base film. The ground contact surface to the rotating cooling drum is also important, and the ground contact surface tends to be smoother than the non-ground surface. Therefore, in order to obtain a smoother release layer surface, the drum ground surface may be adopted as the release layer forming surface.
Further, the 10-point average roughness Rz is preferably 650 nm or more and 1600 nm or less on the surface opposite to the side having the release layer in contact with the OCA adhesive layer. By setting it as such a range, sticking of films can be suppressed and the handling property of OCA can be improved.

(particle)
In the present invention, the particles preferably contained in the base film may be either organic particles or inorganic particles. However, titanium oxide particles, silicon oxide particles, barium sulfate particles, aluminum oxide particles, magnesium oxide particles, Examples include inorganic particles such as calcium carbonate particles, kaolin particles, and talc particles, and organic particles such as polystyrene resin particles, acrylic resin particles, urea resin particles, and melamine resin particles. Examples of organic particles include other resin particles such as polyethylene particles, polypropylene particles, ethylene-propylene terpolymer particles, and olefinic ionomer particles. You may use 1 type (s) or 2 or more types among these. In the present invention, inorganic particles are preferable from the viewpoint of obtaining more preferable surface roughness, light transmittance, and haze value. In particular, titanium oxide particles and silica particles are preferable. In addition, bulky particles are preferable from the viewpoint that voids are hardly formed in the base film, the transparency is excellent, and a suitable surface state is easily obtained. Particularly preferred particles are massive silica particles.

  The base film of the present invention preferably contains particles having an average particle size of 0.1 μm or more and 3 μm or less. The content is preferably 0.02% by mass or more and 0.08% by mass or less based on the mass of the base film. By setting it as such an aspect, it becomes easy to make Rz in the base film surface into the preferable range in this invention as mentioned above, and it becomes easy to achieve Rz of the mold release layer surface which this invention prescribes | regulates. If the average particle size is too large or the content is too large, Rz tends to be too large, while if the average particle size is too small or the content is too small, Rz tends to be too small. . From such a viewpoint, the average particle diameter is more preferably 0.1 μm or more, further preferably 0.2 μm or more, more preferably 2.5 μm or less, and further preferably less than 2.0 μm. Moreover, 0.025 mass% or more is more preferable, as for content, 0.03 mass% or more is further more preferable, 0.07 mass% or less is more preferable, and 0.06 mass% or less is further more preferable.

  In the present invention, two or more kinds of particles having different kinds or different particle diameters can be used in combination. For example, massive particles having a relatively large particle diameter can be used in combination with particles having a relatively small particle diameter, preferably spherical particles. Thereby, fine irregularities are formed on the film surface by relatively small particles, and the effect of improving slipperiness is increased, which is preferable.

(Laminated structure)
The base film in the present invention may be a laminated film of two or more layers having a surface layer to be a surface for forming a release layer and a core layer. For example, a laminated film of 2 to 5 layers (for example, a two-layer structure of surface layer / core layer, a three-layer structure of surface layer / core layer / surface layer, a four-layer structure of surface layer / core layer 1 / core layer 2 / surface layer, etc.) In particular, a three-layer film (surface layer / core layer / surface layer structure) composed of a surface layer and a core layer is preferable, whereby surface protrusion formation by particles contained in the surface layer and inclusion in the core layer are preferable. It becomes possible to adjust both the surface protrusion formation by pushing up from the core layer by the particles formed, and it becomes easier to achieve Rz.

  Also in such a laminated film, the preferred range of the average particle diameter of the particles is the same as in the case of a single layer. The content of the surface layer is preferably 0.01% by mass or more based on the mass of the surface layer, preferably 0.08% by mass or less, more preferably 0.05% by mass or less, and further 0 0.03 mass% or less is preferable. Moreover, in a core layer, it is preferable that they are 0.03 mass% or more and 0.09 mass% or less on the basis of the mass of a core layer. This makes it easier to achieve Rz.

In the case of a laminated film, the thickness of the surface layer (one layer thickness) on the release layer side is preferably 1 to 8 μm, more preferably 2 to 5 μm, and in combination with the above-described particle mode. , Rz is easily achieved. Further, the thickness of the core layer (in the case of having a plurality of core layers, the total thickness thereof) is preferably 15 to 186 μm, and more preferably 25 to 175 μm. By setting it as such an aspect, the processus | protrusion resulting from the particle | grains which a core layer contains is formed in the film surface of the side which forms a release layer, and Rz becomes easier to achieve.
In addition, the base film may contain additives such as an antioxidant, an ultraviolet absorber, a fluorescent brightener, and an antistatic agent as necessary, as long as the object of the present invention is not impaired.

<Release layer>
As the release layer in the present invention, addition type silicone and condensation type silicone can be used. From the viewpoint of productivity, addition type silicone having a quick reaction is preferably used. Condensation type silicone is difficult to cure sufficiently during production, so that the silicone is transferred to the transfer roller in the process of forming the release layer, and deposited, and the deposited silicone is transferred to the film, resulting in a foreign matter defect. There is.

  As for the thickness of the mold release layer in this invention, 0.01-1 micrometer is preferable. When the thickness of the release layer is in the above numerical range, it becomes easy to obtain release properties suitable as an OCA carrier film. Further, the effect of improving the antistatic property can be enhanced. If it is too thick, the antistatic effect tends to decrease, and if it is too thin, the releasability tends to decrease. From such a viewpoint, the thickness is more preferably 0.05 μm or less, more preferably 0.06 μm or more, particularly preferably 0.07 or more, and preferably 0.5 μm or less, particularly preferably 0.3 μm. It is as follows.

<Antistatic layer>
The antistatic layer in the present invention is particularly limited as long as it can satisfy the above-mentioned surface specific resistance value on the surface of the release layer and can form a release layer on the surface and does not impair the object of the present invention. Not. For example, a surfactant type antistatic agent, an antistatic agent by metal oxide fine particles, a siloxane antistatic agent, and the like can be mentioned.

In the present invention, from the viewpoint of excellent surface resistivity and formation of a release layer, as well as excellent adhesion to the release layer by forming a release layer directly on the surface. Particularly preferred are the following antistatic layers.
In the present invention, a particularly preferred antistatic layer is an oxide that uses a siloxane antistatic agent, exhibits antistatic properties by the action of silanol (the following [Chemical Formula 1]), and forms a three-dimensional siloxane network. It is a silicon film.

The silicon oxide film is formed by hydrolysis and / or condensation reaction of a tetrafunctional silicon compound. For example, the moisture that is attached to the film surface or the moisture in the air is sufficient as the moisture that acts on this reaction.
Examples of the tetrafunctional silicon compound include chloropolysiloxanes such as (Cl ₂ SiO) _n , or alkoxysilanes and alkoxypolysiloxanes that easily cause hydrolysis. This compound is preferably hydrolyzed by acting on water before coating, and particularly preferably a partially hydrolyzed product in which 80% or more of side chains and terminal groups are substituted with hydroxyl groups.

の反応によってシラノールを生成し、このシラノール同士が、

の反応によって縮合して三次元構造をもつ酸化ケイ素のガラス状膜を形成する。この反応は室温ないし１４０℃以下の温度で十分に進行すると共に、反応副生成物はガラス状となり、反応残渣のない利点をもつ。 The hydrolyzate and condensation reaction of a tetrafunctional silicon compound can be described with, for example, alkoxysilane “Si (OR) ₄ , R = lower alkyl” under mild reaction conditions.

Silanol is produced by the reaction of

A glass-like film of silicon oxide having a three-dimensional structure is formed by condensation by the above reaction. This reaction proceeds satisfactorily at room temperature to a temperature of 140 ° C. or less, and the reaction by-product becomes glassy and has the advantage of no reaction residue.

When a partial hydrolyzate of a tetrafunctional silicon compound is applied to the film surface, as can be understood from the above, it cures under the influence of temperature and humidity, adheres firmly to the film, and itself has excellent antistatic properties. To have.
The tetrafunctional silicon compound and / or a partial hydrolyzate thereof as described above can be obtained from the market, and examples thereof include Colcoat EC920, Colcoat EC851, Colcoat P, Colcoat N-103X and the like.

  The thickness of the antistatic layer is preferably 0.05 μm or more and 0.5 μm or less. By setting it as such a range, it becomes easy to obtain an excellent surface specific resistance value while maintaining the release performance. In addition, by adopting the above-described preferred antistatic layer, and having the thickness within the above range, the adhesion to the release layer is more excellent. If it is too thin, the surface resistivity tends to increase, and the effect of improving adhesiveness tends to decrease. On the other hand, if it is too thick, it may be difficult to form a release layer. Furthermore, the surface becomes too smooth, the slipperiness is deteriorated, and the cost is not preferable. From these viewpoints, the thickness of the antistatic layer is more preferably 0.06 μm or more, more preferably 0.3 μm or less, and still more preferably 0.2 μm or less.

<Undercoat layer>
In the present invention, for the purpose of improving the adhesion between the base film and the antistatic layer, an undercoat layer can be provided between the base film and the antistatic layer. Such an undercoat layer is preferably formed from a water-soluble organosilane compound.
The water-soluble organosilane compound used for forming the undercoat layer in the present invention has a structure having a hydrolyzable group bonded to a silicon atom and various organic functional groups.

  Examples of such water-soluble organic silane compounds include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxymethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β- (aminoethyl) -γ -Aminopropylmethyldimethoxysilane, N-β- (aminopropyl) -γ-aminopropylmethyldimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane and the like. These are examples of water-soluble organosilane compounds that can be used in the present invention, and are not limited to these. Moreover, 1 type (s) or 2 or more types can be used for a water-soluble organosilane compound.

  The hydrolyzable group in the water-soluble organic silane compound is considered to have an action of forming a hydroxyl group by hydrolysis and strengthening the bond with the inorganic substance in the antistatic layer applied on the undercoat layer. Strong organic functional group has strong affinity with polyester film, coating layer binder resin, etc. For example, primary or secondary amino group in the molecule reacts with many functional groups including hydroxyl group, carboxyl group and epoxy group. It is considered that the bond between the film and the undercoat layer and between the undercoat layer and the antistatic layer is strengthened.

The water-soluble organosilane compound is usually used as an aqueous solution at a concentration of 0.1 to 5.0%, and the coating amount on the surface of the polyester film is 0.02 to 0.2 g / m ² (after drying). preferable. The application of the water-soluble organosilane compound may be performed during the film forming process, or may be performed at a place different from the film forming process. When performing in a film forming process, it can be applied to an unstretched film, a uniaxially stretched film (particularly a longitudinally stretched film), a biaxially stretched film, a film after biaxial stretching and heat setting, and the like. Among these, it is preferable to apply to a longitudinally stretched film before being subjected to lateral stretching. As the coating method, for example, various coating methods such as spin coating, gravure coating, kiss coating, bar coating, and reverse coating can be used. Coating is on one or both sides of a polyester film.

<Method for producing release film>
(Manufacturing method of base film)
The base film in the present invention is preferably a biaxially stretched film. Such a biaxially stretched film can be produced by a conventionally known method. For example, in the case of a biaxially stretched film made of polyester, after drying the polyester, it is melted in an extruder at a temperature of Tm to (Tm + 70) ° C. (where Tm represents the melting point (unit: ° C.) of the polyester). , Extruded from a die (for example, T-die, I-die, etc.) onto a rotating cooling drum, rapidly cooled at 20 to 90 ° C. to produce an unstretched film, and then the unstretched film is (Tg-10) to ( Tg + 70) ° C (where Tg represents the glass transition temperature of the polyester (unit: ° C)) 2.5 to 8.0 times, preferably 2.9 to 5.0 times in the machine direction. Preferably, the film is stretched at a magnification of 3.2 to 4.0 times, and is 2.5 to 8.0 times, preferably 3.1 to 5.2 times, more preferably 3.4 to 4.2 times in the transverse direction. 1 at a temperature of 180 to 250 ° C. if necessary. It can be prepared by fixing 60 seconds heat. By setting the draw ratio within the above numerical range, the thickness unevenness can be further reduced.
In the above, when the surface of the rotary cooling drum is a mirror-finished surface, as will be described later, by forming an antistatic layer and a release layer on the surface of the film grounded to the surface, a preferable release in the present invention Since it becomes easy to obtain the layer surface, it is preferable.

In addition, the thickness of the base film in the present invention is not particularly limited as long as the base film has a proper stiffness, but is preferably 20 μm or more, more preferably 30 μm or more. On the other hand, it is difficult to handle even if it is too thick, preferably 188 μm or less, more preferably 175 μm or less, and even more preferably 150 μm or less. Within such a range, it is suitable as a release film for OCA.
Furthermore, when using as a carrier film, 38-188 micrometers, Furthermore, 50-150 micrometers is preferable for a moderate stiffness. Moreover, when using as a separator, 20-100 micrometers, Furthermore, 38-75 micrometers is preferable.

(Method for forming antistatic layer)
The antistatic layer in the present invention is a coating liquid containing each component constituting the antistatic layer (hereinafter sometimes referred to as an antistatic layer coating liquid) is applied onto a base film, dried, It is formed by curing. The surface to be coated is preferably the surface on the side of the base film that is in contact with the rotary cooling drum by extruding the resin from the die from the viewpoint that the Rz on the surface of the release layer is easily set to a preferred value.

As a coating method for applying the antistatic layer coating liquid to the base film, any known coating method can be applied, for example, gravure roll coating method, reverse roll coating method, die coating method, kiss coating method, reverse kiss coating method. The offset gravure coating method, the Mayer bar coating method, the roll brush method, the spray coating method, the air knife coating method, the impregnation method, the curtain coating method, the doctor blade method and the like can be applied alone or in combination. Further, for the purpose of improving the stability of the coating appearance such as repelling, the coating liquid can contain a slight amount of a surfactant.
As conditions for drying and curing after applying the antistatic layer coating solution, it is preferable to heat at a temperature of 50 ° C. or higher and 150 ° C. or lower for 10 seconds or longer and 120 seconds or shorter, and 70 ° C. or higher and 140 ° C. or lower. It is more preferable to heat at a temperature of 20 seconds to 90 seconds.

(Formation method of release layer)
The release layer in the present invention is a coating liquid containing each component constituting the release layer (hereinafter, sometimes referred to as a release layer coating liquid) applied on the antistatic layer of the base film. It is formed by drying and curing. The surface to be coated is preferably the surface on the side of the base film that is in contact with the rotary cooling drum by extruding the resin from the die from the viewpoint that the Rz on the surface of the release layer is easily set to a preferred value.

  As a coating method for applying the release layer coating liquid to the base film, any known coating method can be applied, for example, gravure roll coating method, reverse roll coating method, die coating method, kiss coating method, reverse kiss coating method. The offset gravure coating method, the Mayer bar coating method, the roll brush method, the spray coating method, the air knife coating method, the impregnation method, the curtain coating method, the doctor blade method and the like can be applied alone or in combination. Further, for the purpose of improving the stability of the coating appearance such as repelling, the coating liquid can contain a slight amount of a surfactant.

  As conditions for drying and curing after applying the release layer coating solution, it is preferable to heat at a temperature of 100 ° C. or higher and 180 ° C. or lower for 10 seconds or longer and 120 seconds or shorter, 110 ° C. or higher and 160 ° C. or lower. It is more preferable to heat at a temperature of 20 seconds to 90 seconds, and particularly preferable to heat at a temperature of 120 ° C. to 140 ° C. for 30 seconds to 60 seconds. By adopting the drying conditions as described above, the strength of the release layer can be further increased, and furthermore, the generation of heat wrinkles in the polyester film can be suppressed.

<Characteristics of release film>
(Peeling force)
The release film in the present invention preferably has a normal temperature peeling force (peeling force at normal temperature measurement) on the surface of the release layer of 19.5 mN / 25 mm or more and 680 mN / 25 mm or less. When the room temperature peeling force is in the above numerical range, the peeling force with the OCA adhesive layer is stable, and the OCA adhesive layer can be peeled with an appropriate peeling force. When the room temperature peeling force is too low, there is a tendency that floating tends to occur between the OCA adhesive layer and the release film in the OCA manufacturing process. If the peel force is too high, it tends to be difficult to peel from the OCA adhesive layer when using a finished OCA product. From such a viewpoint, the room temperature peeling force when used as a carrier film is more preferably 50 mN / 25 mm or more and 600 mN / 25 mm or less, and still more preferably 80 mN / 25 mm or more and 580 mN / 25 mm or less. When used as a separator, the room temperature peeling force is more preferably 20 mN / 25 mm or more and 100 mN / 25 mm or less, still more preferably 22 mN / 25 mm or more and 80 mN / 25 mm or less.

  The peeling force can be achieved by appropriately adjusting the mode of the release layer. That is, when the release layer is of a silicone type, the room temperature peeling force tends to increase when the number of crosslinking points of the silicone used is reduced or the coating film thickness is increased. Further, when the remaining Si—H is decreased, the heat peeling force tends to decrease, and when the remaining Si—H is increased, the heat peeling force tends to increase.

(Residual adhesion rate)
The residual adhesive force on the surface of the release layer of the release film in the present invention is preferably 80% or more, more preferably 90% or more, and further preferably 95% or more. When the value of the residual adhesion rate is within the above range, there can be obtained an OCA with less migration components from the release layer and better quality, that is, more stable adhesion.
Such residual adhesion rate can be achieved by reducing the migration component from the release layer. For example, unreacted components may be reduced or the crosslinking reaction may be sufficiently advanced.

(Adhesion)
The release film in the present invention is desirably excellent in adhesion of the release layer to the base film. If the release layer has poor adhesion, the release layer may fall off due to rubbing during handling, or the release layer may be transferred to the OCA surface when the release film is peeled off from the OCA. To increase the adhesion of the release layer to the substrate film, that is, increase the adhesion between the substrate film and the antistatic layer, or increase the adhesion between the antistatic layer and the release layer. However, there are methods such as corona treatment, plasma treatment, flame treatment and the like in which the base film is pretreated for improving adhesion as described above, and it is preferable to employ these in the present invention. Moreover, the effect of improving the adhesion between the antistatic layer and the release layer can be enhanced by adopting the above-described preferred antistatic layer mode.

<Optical transparent adhesive sheet>
An optical transparent adhesive sheet (OCA) can be prepared using the release film of the present invention as described above. Such OCA has a structure of a laminate having release films on both sides of the OCA adhesive layer such that the OCA adhesive layer side becomes a release layer. It is preferable to employ the release film of the present invention on both surfaces of the release film in such a laminate. Preferably, one is a release film having a preferred embodiment as a separator, and the other is a release film having a preferred embodiment as a carrier film.

  Hereinafter, the present invention will be further described by examples. Each characteristic value was measured by the following method.

(1) Room temperature peeling force A polyester adhesive tape (No. 31B, manufactured by Nitto Denko Corporation) is bonded to the surface of the release layer of the sample film, and after pressing with a 5 kg pressure roller, the release layer and the adhesive tape are peeled off. The moth (unit: mN / 25 mm) was measured with a tensile tester. The peeling angle was 180 degrees and the head speed was 300 mm / min. The room temperature peeling force was determined as an average value at any five locations.

(2) Residual adhesion rate After sticking a polyester pressure-sensitive adhesive tape (No. 31B, manufactured by Nitto Denko Corporation) on a cold-rolled stainless steel plate (SUS304) specified in JIS G4305, it was peeled and the peel strength was measured. And a basic adhesive strength (f0) (unit: N / 25 mm). Next, after a new polyester pressure-sensitive adhesive tape was pressure-bonded to the surface of the release layer of the sample film with a 5 kg pressure roller, it was left for 30 seconds and then peeled off. And this peeled polyester adhesive tape was affixed on the said stainless steel plate, it peeled, the peeling force was measured, and it was set as the residual adhesive force (f) (unit: N / 25mm). The residual adhesive rate was determined from the obtained basic adhesive force (f0) and residual adhesive force (f) using the following formula.
Residual adhesion rate (%) = (f / f0) × 100

(3) Adhesiveness After producing a release film, the sample was left for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 55% RH. Next, with respect to the sample after the aging treatment, the release layer surface was rubbed strongly 10 times with the thumb, and a rub-off test was performed. At this time, the thumb was thoroughly wiped with gauze preliminarily containing ethanol and degreased before carrying out the above operation. About the obtained sample after the rub-off test, the state of the release layer in the portion rubbed with the thumb was visually observed and judged according to the following criteria.
○: No cloudiness is observed in the release layer by visual observation.
Δ: Some cloudiness was observed in the release layer visually.
X: Cloudiness was observed in the release layer visually.
Furthermore, the cellophane adhesive tape was affixed to the part rubbed with the thumb, and the degree of catch when peeling it was evaluated according to the following criteria. The presence of catch means that the release layer has been removed.
○: There is no catch when the cellophane adhesive tape is peeled off.
Δ: When the cellophane adhesive tape is peeled off, there is a slight catch.
X: There is a catch when the cellophane adhesive tape is peeled off.
XX: When the cellophane adhesive tape is peeled off, there is a strong catch (a catch equivalent to a part having no release layer).

(4) 10-point average roughness (Rz)
Using a three-dimensional roughness measuring device SE-3CKT (manufactured by Kosaka Laboratory Co., Ltd.), the projection profile on the surface of the release layer of the release film was measured with a vertical magnification of 5000 times, a lateral magnification of 200 times, a scanning pitch of 2 nm, and a measurement length of 1 mm. , Measured with a cut-off of 0.25 mm. In the obtained protrusion profile, 5 points from the highest peak (Hp) and 5 points from the lower valley (Hv) were taken, and the 10-point average roughness (Rz, unit: nm) was determined by the following formula. . For the analysis, a three-dimensional roughness analyzer SPA-11 (manufactured by Kosaka Laboratory Ltd.) was used.

Further, from the obtained projection profile (horizontal axis: projection height, vertical axis: projection profile of the number of projections), the number of projections (pieces each having a height of 0.2 μm or more, 0.6 μm or more, 1.2 μm or more) / Mm ² ).

(5) OCA haze evaluation (5-1) Creation of OCA A mold release film (1-x in Examples and Comparative Examples) as a release film for a carrier film on a flat glass substrate, and a mold release surface Placed on the four sides of the release film to place a 2.0 mm thick spacer to form a lower mold, and mixed and defoamed uncured liquid silicone gel (Asahi Kasei Wacker) at the center of the release film Silicone Co., Ltd., product number: SLJ3363) was poured to prevent entrainment of bubbles, and then a release film as a release film for separators (2-x in Examples and Comparative Examples) so as not to entrap bubbles. 1) is contact-coated on the surface of the liquid silicone gel raw material, and then a flat glass plate serving as an upper push mold is placed on the release film for the separator. It was pressed by hand to form a spacer thickness. Next, together with the glass plate mold of the molding step, the silicone gel raw material is heated and cured in a hot air oven at 70 ° C. for 1 hour, then removed from the oven, the glass substrate is removed, naturally cooled to room temperature, and OCA ( (Release film for carrier film / OCA adhesive layer / release film for separator)). The OCA adhesive layer was adjusted to have a thickness of 300 μm.

(5-2) Haze evaluation Next, the separator was peeled off from the OCA obtained as described above and bonded to a polycarbonate plate, and then the carrier film was peeled off. Haze meter HCM-2B, wavelength: 580 nm) was used, and the haze was measured with the OCA side facing the light source. This measured value was set to Hz (1).
Next, in the OCA adhesive layer, a polycarbonate plate similar to the above is bonded to the surface on which the carrier film is peeled off, and the haze is measured in the same manner in a state where the surface haze is canceled. Hz (2). These numerical values were evaluated according to the following criteria.
A: Hz (1) -Hz (2) ≦ 0.3
○: 0.3 <Hz (1) −Hz (2) ≦ 0.45
Δ: 0.45 <Hz (1) −Hz (2) ≦ 0.55
X: 0.55 <Hz (1) -Hz (2)

(6) Surface resistivity The surface resistivity of the release layer surface was measured with a measuring instrument (R8340 / R12704) manufactured by Advantest Corporation. The measurement environment was a sample film which was aged for 24 hours in an atmosphere having a temperature of 23 ° C. and a relative humidity of 55% RH, and was measured with the above apparatus. The surface resistance value was evaluated according to the following criteria.

(7) OCA handleability First, a separator was peeled off from the OCA created in the above (5-1), a new separator was attached again, and an OCA for handling property evaluation was created. After 20 sheets of OCA (this is referred to as 1 set) obtained in this manner were stacked and then each set was picked up, 2 or more sets of OCA sheets were charged by charging. The leaf sheets were checked for overlapping and evaluated according to the following criteria.
○: All 20 sheets of sheets could be taken without overlapping two or more sets.
[Delta]: Four or less sheets of 20 sheets or more followed by two or more sheets, but other sheets could be taken without overlapping.
X: More than 5 sets of 20 sheets of 20 sets overlapped each other.

(8) Glass transition temperature (Tg), melting point (Tm)
In the case of a resin sample, 10 mg of the sample, and in the case of a film sample, 20 mg of the sample are set in a DSC apparatus (differential scanning calorimeter) manufactured by PerkinElmer, Inc., and the temperature is increased from room temperature to 300 ° C. at 20 ° C./min. After maintaining at a temperature of 300 ° C. for 5 minutes, the sample was rapidly cooled in liquid nitrogen, and the rapidly cooled sample was heated to about 300 ° C. at 10 ° C./min to increase the glass transition temperature (Tg) (unit: ° C.) and the melting point (Tm ) (Unit: ° C.) was measured.

(9) Average particle diameter of particles On a sample stage, powder particles are scattered so that individual particles do not overlap as much as possible, and a gold thin film deposition layer is formed on the surface with a thickness of 200 to 300 angstroms by a gold sputtering device. Then, observed at a magnification of 10,000 to 3 using a scanning electron microscope, and with a Luzex 500 manufactured by Japan Regulator Co., Ltd., the major axis (Dli), minor axis (Dsi), and area of at least 110 particles The equivalent circle diameter (Di) was determined.
The number n of particles was used, and the value obtained above was used in the following formula, and the number average value of the area equivalent particle diameter (Di) was defined as the average particle diameter (D).

(10) Sliding property evaluation (release film handling property)
According to JIS-K7125, the static friction coefficient (μs) on the surface of the release layer was measured. The measurement was performed 5 times and the average value was calculated. The measured values were evaluated according to the following criteria.
○: The coefficient of friction is <0.5
×: The coefficient of friction is ≧ 0.5
Moreover, the following reference | standard evaluated about the damage | wound of the film surface after the said measurement.
○: No scratches are observed on the film surface after measurement.
X: Fine scratches are observed on the film surface after measurement.

[Example 1-1]
(Base film)
100 parts by mass of polyethylene terephthalate pellets (PET) having an intrinsic viscosity of 0.65 dl / g (glass transition temperature Tg = 78 ° C., melting point Tm = 258 ° C. according to DSC method), bulk silicon oxide having an average particle size of 1.7 μm The particles were mixed at a ratio of 0.05 part by mass, dried, melted and mixed with a biaxial type extruder, and extruded onto a cooling drum to obtain an unstretched sheet. Subsequently, the unstretched sheet was stretched at 90 ° C. at a longitudinal stretching ratio of 3.3 times and at 130 ° C. at a transverse stretching ratio of 3.5 times, and then heat-treated at a heat setting temperature of 210 ° C. for 4 seconds to obtain a thickness of 100 μm. A biaxially stretched polyester film was obtained.
(Antistatic layer)
A polysiloxane hydrolyzate (manufactured by Colcoat Co., Ltd .: Colcoat P) was diluted with isopropyl alcohol (IPA) to prepare a solution having a solid content of 1.5 wt% to prepare an antistatic layer coating solution. This antistatic layer coating solution is applied on the surface of the polyester film obtained above in contact with the cooling drum by a conventional roll coating, and dried at a drying temperature of 130 ° C. for 30 seconds. An antistatic layer having a thickness of 10 μm was formed to obtain an antistatic film.
(Release layer)
In a mixed solvent composed of 70 parts by mass of methyl ethyl ketone (MEK) and 30 parts by mass of toluene, 5.3 parts by mass of silicone (manufactured by Toray Dow Corning Co., Ltd .: BY24-312) having polydimethylsiloxane as a main component is dissolved, and a catalyst is obtained. (Toray Dow Corning Co., Ltd. product: SRX-312) was mixed at a ratio of 2 parts by mass with respect to 100 parts by mass of silicone to prepare a release layer coating solution. This release layer coating solution is applied onto the surface of the antistatic film obtained above by applying a conventional roll coat, and dried at a drying temperature of 130 ° C. for 30 seconds to obtain a dry film thickness. Formed a release layer of 0.10 μm to obtain a release film. The properties of the obtained release film are shown in Table 1.

[Example 1-2]
The particles added to the base film are 0.04 parts by mass of bulk silicon oxide particles having an average particle diameter of 1.7 μm and 0.02 parts by mass of alumina particles having an average particle diameter of 0.1 μm with respect to 100 parts by mass of PET. A biaxially stretched polyester film having a thickness of 100 μm was obtained in the same manner as in Example 1-1 except that. Further, an antistatic layer and a release layer were sequentially formed in the same manner as in Example 1-1 to obtain a release film. The properties of the obtained release film are shown in Table 1.

[Example 1-3]
Lumped silicon oxide having 100 parts by mass of polyethylene terephthalate pellets (PET) having an intrinsic viscosity of 0.65 dl / g (glass transition temperature Tg = 78 ° C., melting point Tm = 258 ° C., DSC method) and an average particle diameter of 1.7 μm A mixture of particles at a ratio of 0.02 parts by mass is used as the surface layer side polyester (A), and 0.08 parts by mass of bulk silicon oxide particles having an average particle diameter of 1.7 μm is added to 100 parts by mass of the same polyethylene terephthalate pellets. Was mixed as a core layer side polyester (B). Each polyester is dried, the polyester (A) is supplied to the first extruder, the polyester (B) is supplied to the second extruder, and the polyester (A) is melted using a three-layer feedblock device. ) Is branched into two layers as a surface layer, polyester (B) is branched into one layer as a core layer, and extruded onto a cooling drum as a melt in a three-layered state of surface layer / core layer / surface layer to obtain an unstretched sheet It was. Subsequently, the unstretched sheet was stretched at 90 ° C. to a longitudinal stretching ratio of 3.3 times and at 130 ° C. to a transverse stretching ratio of 3.5 times, and then heat-treated at 210 ° C. for 4 seconds to obtain a 100 μm-thick An axially stretched polyester film was obtained. The thicknesses of both surface layers were controlled to be 6 μm and the thickness of the core layer was 88 μm. Further, an antistatic layer and a release layer were sequentially formed on the obtained polyester film in the same manner as in Example 1-1 to obtain a release film. The properties of the obtained release film are shown in Table 1.

[Example 1-4]
An antistatic layer and a release layer were sequentially formed in the same manner as in Example 1-1 except that the release layer coating solution and the release layer coating solution were applied to the surface of the polyester film that was not in contact with the cooling drum. A release film was obtained. The properties of the obtained release film with antistatic properties are shown in Table 1.

[Example 1-5]
The particle to be added to the base film was the same as Example 1-4 except that 0.06 part by mass of bulk silicon oxide particles having an average particle diameter of 1.7 μm with respect to 100 parts by mass of PET. An axially stretched polyester film was obtained. Further, as in Example 1-4, the same antistatic layer and release layer as in Example 1-1 were sequentially formed on the surface not in contact with the cooling drum to obtain a release film. The properties of the obtained release film are shown in Table 1.

[Example 1-6]
The particles added to the surface layer side polyester (A) are 0.07 parts by mass of bulk silicon oxide particles having an average particle diameter of 1.7 μm with respect to 100 parts by mass of the PET in the surface layer side polyester (A). ) Was added in the same manner as in Example 1-3, except that 0.08 parts by mass of bulk silicon oxide particles having an average particle diameter of 1.7 μm with respect to 100 parts by mass of PET in the core layer side polyester (B). Thus, a biaxially stretched polyester film having a thickness of 100 μm was obtained. Further, a release film was obtained in the same manner as in Example 1-1. The properties of the obtained release film are shown in Table 1.

[Example 1-7]
A release film was obtained in the same manner as in Example 1-1 except that the coating thickness of the antistatic layer was 0.20 μm. Table 1 shows the evaluation results of the obtained release film.

[Example 1-8]
A release film was obtained in the same manner as in Example 1-1 except that the coating thickness of the antistatic layer was changed to 0.07 μm. Table 1 shows the evaluation results of the obtained release film.

[Comparative Example 1-1]
A particle having a thickness of 100 μm was added in the same manner as in Example 1-1 except that particles added to the base film were 0.07 parts by mass of bulk silicon oxide particles having an average particle diameter of 1.7 μm with respect to 100 parts by mass of PET. A biaxially stretched polyester film was obtained, and a release film was obtained in the same manner as in Example 1-1. The properties of the obtained release film are shown in Table 1.

[Comparative Example 1-2]
A particle having a thickness of 100 μm was added in the same manner as in Example 1-1 except that particles added to the base film were 0.008 parts by mass of bulk silicon oxide particles having an average particle size of 1.7 μm with respect to 100 parts by mass of PET. A biaxially stretched polyester film was obtained, and a release film was obtained in the same manner as in Example 1-1. The properties of the obtained release film are shown in Table 1.

[Comparative Example 1-3]
An antistatic film was obtained in the same manner as in Example 1-5 except that the release layer was not provided on the antistatic layer. The properties of the obtained antistatic film are shown in Table 1.

[Comparative Example 1-4]
A release film was obtained in the same manner as in Example 1-5 except that the antistatic layer was not provided on the polyester film. The properties of the obtained release film are shown in Table 1.

[Comparative Example 1-5]
For the formation of the antistatic layer, an aqueous dispersion of poly (3,4-ethylenedioxythiophene) (PEDOT) / polystyrene sulfonic acid (PSS) (manufactured by Nagase ChemteX: Vitron P) is diluted with distilled water to obtain a solid content. A release film was obtained in the same manner as in Example 1-5 except that a 1.0 wt% solution was prepared, and this was used as the antistatic layer coating solution, so that the dry coating thickness was 0.15 μm. It was. In the obtained release film, inhibition of curing of the release layer occurred due to the antistatic layer component, and poor curing of the release layer was observed. The properties of this release film are shown in Table 1.

[Example 2-1]
(Base film)
100 parts by mass of polyethylene terephthalate pellets (PET) having an intrinsic viscosity of 0.65 dl / g (glass transition temperature Tg = 78 ° C., melting point Tm = 258 ° C. according to DSC method), bulk silicon oxide having an average particle size of 1.7 μm The particles were mixed at a ratio of 0.05 part by mass, dried, melted and mixed with a biaxial type extruder, and extruded onto a cooling drum to obtain an unstretched sheet. Subsequently, the unstretched sheet was stretched at 90 ° C. at a longitudinal stretching ratio of 3.3 times and at 130 ° C. at a transverse stretching ratio of 3.5 times, and then heat-treated at a heat setting temperature of 210 ° C. for 4 seconds to obtain a thickness of 50 μm. A biaxially stretched polyester film was obtained.
(Antistatic layer)
A polysiloxane hydrolyzate (manufactured by Colcoat Co., Ltd .: Colcoat P) was diluted with isopropyl alcohol (IPA) to prepare a solution having a solid content of 1.5 wt% to prepare an antistatic layer coating solution. This antistatic layer coating solution is applied on the surface of the polyester film obtained above in contact with the cooling drum by a conventional roll coating, and dried at a drying temperature of 130 ° C. for 30 seconds. An antistatic layer having a thickness of 10 μm was formed to obtain an antistatic film.
(Release layer)
In a mixed solvent composed of 70 parts by mass of methyl ethyl ketone (MEK) and 30 parts by mass of toluene, 6 parts by mass of silicone (manufactured by Shin-Etsu Chemical Co., Ltd .: TFR1476) containing polydimethylsiloxane as a main component is dissolved, and a catalyst (Shin-Etsu Chemical Co., Ltd.) is dissolved. A release layer coating solution was prepared by mixing 2 parts by mass with 100 parts by mass of silicone. This release layer coating solution is applied onto the surface of the antistatic film obtained above by applying a conventional roll coat, and dried at a drying temperature of 130 ° C. for 30 seconds to obtain a dry film thickness. Formed a release layer of 0.10 μm to obtain a release film. The properties of the obtained release film are shown in Table 2.

[Example 2-2]
A release film was obtained in the same manner as in Example 2-1, except that the coating thickness of the antistatic layer was 0.20 μm. Table 2 shows the evaluation results of the obtained release film.

[Example 2-3]
A release film was obtained in the same manner as in Example 2-1, except that the coating thickness of the antistatic layer was 0.07 μm. Table 2 shows the evaluation results of the obtained release film.

[Comparative Example 2-1]
A release film was obtained in the same manner as in Example 2-1, except that the antistatic layer was not applied. Table 2 shows the evaluation results of the obtained release film.

[Examples 3-1 to 3-10, Comparative examples 3-1 to 3-6]
Using the release film (antistatic film) obtained above, OCA was produced in the combinations shown in Table 3 according to the method of “(5-1) Creation of OCA”. The evaluation results are shown in Table 3.

In Comparative Example 3-3, the carrier film was poorly slid and could not be handled well in the OCA coating process, and an OCA sample worthy of evaluation could not be created. Therefore, OCA haze evaluation and OCA handleability evaluation could not be performed. .
In Comparative Example 3-4, since the peelability of the carrier film was insufficient and the carrier film could not be peeled off, OCA haze evaluation could not be performed. Although the OCA handleability was a good result, since the carrier film could not be peeled, the result was not usable finally.
In Comparative Example 3-6, since the curing of the release layer of the carrier film was insufficient, an OCA sample worthy of evaluation could not be produced, and OCA haze evaluation could not be performed. Although the OCA handleability was a good result, the carrier film could not be peeled off well, and the release layer adhered to the OCA, so that it could not be used finally.

  The release film of the present invention can be suitably used as an OCA release film.

Claims (6)

A release film having an antistatic layer and a release layer in this order on at least one surface of a base film, wherein the 10-point average roughness Rz on the release layer surface is 650 nm or more and 1600 nm or less, and the release film A release film for a transparent adhesive sheet for optical use, having a surface specific resistance value of 10 ⁶ Ω / □ or more and 10 ¹² Ω / □ or less on the surface of the layer.   The release film for transparent optical adhesive sheets for optical use according to claim 1, wherein the antistatic layer is a silicon oxide film formed by hydrolysis and / or condensation reaction of a tetrafunctional silicon compound.   The release film for transparent adhesive sheets for optical use according to claim 1 or 2, wherein the peeling force on the surface of the release layer is 19.5 mN / 25 mm or more and 680 mN / 25 mm or less when measured at room temperature.   The mold release film for optical transparent adhesive sheets of any one of Claims 1-3 whose 10-point average roughness Rz in a mold release layer surface is 650 nm or more and 1200 nm or less. In the release layer surface is more than the height 0.2μm projections 100 to 800 pieces / mm ^2, more height 0.6μm projections is 10 to 130 pieces / mm ^2, more height 1.2μm The mold release film for an optical transparent adhesive sheet according to claim 4, wherein the number of protrusions is 10 pieces / mm ² or less.   The laminated body which has a release film of any one of Claims 1-5 on both surfaces of an adhesion layer.