JP2018043458A - Release film - Google Patents

Abstract

In the manufacturing process of an optical display panel, the problem that the peeling means of the release film and its surroundings are contaminated, and the problem that peeling stripes (traces) are generated on the surface of the adhesive layer due to zipping are suppressed. Provide mold film.
A release film having a release layer on at least one surface of a film substrate, wherein the ratio (B / A) of peel strength A and peel strength B defined below is 0.70. A release film that is 0.92. A release film having a peel strength A of 30 to 130 mN / 50 mm. <Peel strength A> A test piece was prepared by laminating a release layer of a release film and an adhesive surface of an adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation; substrate thickness 25 μm / total thickness 53 μm). In this test piece, the peel strength when the adhesive tape side is peeled off at 180 °. <Peel strength B> The peel strength when the release film side is peeled off at 180 ° for a test piece prepared in the same manner as described above.
[Selection figure] None

Description

  The present invention relates to a release film, and more particularly to a release film suitable for manufacturing an optical display panel.

  In the manufacturing process of an optical display panel such as a liquid crystal panel or an organic EL panel, an optical film such as a polarizing plate is bonded to an optical display element such as a liquid crystal cell or an organic EL element via an adhesive layer (bonding) Process).

  In the above process, an optical film laminate in which an adhesive layer and a release film (or carrier sheet) are laminated in this order is used as a long roll on the optical film, and this optical film laminate is bonded to an optical display element. Continuously supplied to the combined process. In the bonding step, the release film is continuously peeled from the conveyed optical film laminate, and the optical film and the optical display element are bonded via the exposed adhesive layer.

  The manufacturing method of the optical display panel including the said bonding process is described in patent documents 1-4, for example.

Japanese Patent Laid-Open No. 11-95028 JP 2009-122641 A JP 2011-85632 A JP 2012-48045 A

  In the said patent document, the roller for peeling and a peeling board are used as a peeling means for peeling a release film from an optical film laminated body. The larger the peeling angle of the release film, the easier it is to peel off. That is, it is preferable from a peelable viewpoint that the holding angle of the peeling means with respect to the release film is large.

  However, when the release angle of the release film is increased, for example, when the release angle is 100 ° or more, the contact area between the release film and the release means is increased, and the shavings and oligomer components of the release film are removed from the release means and its There may be an inconvenient problem of adhering to and contaminating the periphery, or a problem that zipping occurs to cause peeling stripes (traces) on the adhesive layer surface.

  Therefore, the object of the present invention is that in the manufacturing process of the optical display panel, there is a problem that the peeling means of the release film and its surroundings are contaminated, and a problem that peeling streaks (traces) are generated on the surface of the adhesive layer by zipping. It is in providing the release film which is suppressed.

The above problems are basically solved by the following invention.
[1] A release film having a release layer on at least one surface of a film substrate, wherein the ratio (B / A) of peel strength A and peel strength B defined below is 0.70 to 0 A release film characterized by being .92.

<Peel strength A>
A test piece was prepared by laminating a release layer of the release film and an adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation; substrate thickness 25 μm / total thickness 53 μm). Is the peel strength when the adhesive tape side is peeled off at 180 °.

<Peel strength B>
The peel strength when the release film side is peeled off at 180 ° for the test piece prepared in the same manner as described above.
[2] The release film according to [1], wherein the peel strength A is in the range of 30 to 130 mN / 50 mm.
[3] The release film according to [1] or [2], wherein the release film has a haze value of 6 to 14%.
[4] The release film according to any one of [1] to [3], wherein the surface roughness SRa of the surface opposite to the surface having the release layer of the release film is in the range of 10 to 50 nm.
[5] The release film according to any one of [1] to [4], wherein the film substrate is a biaxially oriented polyester film.
[6] The release film according to [5], wherein the film substrate has a three-layer laminated structure of A layer / B layer / A layer or A layer / B layer / C layer.
[7] The release film according to any one of [1] to [6], which has an anchor layer between the film substrate and the release layer.
[8] The release film according to any one of [1] to [7], which is used in the following method for producing an optical display panel.

<Method for manufacturing optical display panel>
The release film is peeled off at a peeling angle (θ) of 100 ° or more by a peeling means from the long optical film laminate in which the pressure-sensitive adhesive layer and the release film are laminated in this order on the optical film, and then passed through the pressure-sensitive adhesive layer. The manufacturing method which bonds an optical film and an optical display element.

  By using the release film of the present invention, for example, in the manufacturing process of an optical display panel, there is a problem that the release means of the release film and its periphery are contaminated, and there are peeling stripes (traces) on the surface of the adhesive layer due to zipping. The problem of occurring is suppressed.

FIG. 1 is a schematic side view showing an example of a method for manufacturing an optical display panel according to the present invention. FIG. 2 is a schematic cross-sectional view of each member in the manufacturing process of FIG. FIG. 3 is a schematic side view for explaining the peeling angle (θ) in FIG. 1.

  The release film of the present invention is preferably used in a method for producing an optical display panel. Hereinafter, an example of the manufacturing method of the optical display panel in which the release film of the present invention is preferably used will be described.

[Method of manufacturing optical display panel]
In the method for producing an optical display panel in which the release film of the present invention is preferably used, the release film is removed from the long optical film laminate in which the adhesive layer and the release film are laminated in this order on the optical film by a peeling means. This is a production method in which an optical film and an optical display element are bonded through an adhesive layer after peeling at a peeling angle (θ) of at least °.

  A method for manufacturing the optical display panel will be described in detail with reference to FIGS. FIG. 1 is a schematic side view showing an example of a method for manufacturing an optical display panel according to the present invention. FIG. 2 is a schematic cross-sectional view of each member in the manufacturing process of FIG. FIG. 3 is a schematic side view for explaining the peeling angle θ of the release film in FIG. 1.

  1 and 2, the release film 13 is peeled off by the peeling means 3 from the long optical film laminate 1 (FIG. 2 a) in which the adhesive layer 12 and the release film 13 are laminated in this order on the optical film 11. The optical film 10 with an adhesive layer (FIG. 2b) is bonded to the optical display element 2 via the adhesive layer 12, and the optical display panel 5 (FIG. 2c) is manufactured.

  In the manufacturing method of the optical display panel described above, the method of supplying the long optical film laminate 1 is not shown in FIG. The method of providing the process of laminating | stacking a long optical film and a long release film through an adhesive layer in the process is mentioned. In this case, the long release film is supplied as a long roll. Here, the long length is generally 100 m or more, preferably 500 m or more, and more preferably 1000 m or more.

  Moreover, in the manufacturing method of an optical display panel, the optical display element 2 is often supplied in the form of a sheet of a predetermined size, and the optical film with an adhesive layer 10 in which the optical film 11 and the adhesive layer are laminated is an optical display. After being bonded to the element 2, it may be cut according to the size of the optical display element 2, or the optical film 11 and the adhesive layer 12 of the long optical film laminate 1 before bonding are optically bonded. A half cut for providing a score line in accordance with the size of the display element 2 may be performed.

  Moreover, although not shown in FIG. 1, the optical display element 2 may be conveyed by a carrier sheet.

  Examples of the peeling means for peeling the release film 13 from the long optical film laminate 1 include a peeling plate and a roller. In the embodiment of FIG. 1, a peeling plate is used as the peeling means 3, but a roller may be used. The release film 13 peeled from the long optical film laminate 1 is wound and collected by a winding device (not shown).

  FIG. 3 is a schematic side view for explaining the peeling angle (θ) of the release film. FIG. 3A is a schematic side view when a peeling plate is used as the peeling means, and FIG. 3B is a schematic side view when a roller is used as the peeling means.

  In this invention, it is preferable that peeling angle (theta) when the release film 13 is peeled by the peeling means 3 is 100 degrees or more. By setting the peeling angle θ to 100 ° or more, the peelability of the release film is improved. The peeling angle θ is further preferably 120 ° or more, and particularly preferably 140 ° or more. The upper limit is about 175 °.

  When the peeling means 3 is a peeling plate, the peeling angle (θ) can be easily controlled within the above range by using a peeling plate having a sharp tip as shown in FIG. Further, when the peeling means is a roller, the peeling angle (θ) can be easily controlled within the above range by using a roller having a relatively small diameter, for example, a roller having a diameter of 150 mm or less, and further a diameter of 100 mm or less. .

  Examples of the optical display panel in the present invention include a liquid crystal panel and an organic EL panel, and examples of the optical display element include, but are not limited to, a liquid crystal display element and an organic EL element. Examples of the optical film in the present invention include, but are not limited to, a polarizing plate, a retardation film, a gas barrier film, and an antireflection film.

[Release film]
The release film of the present invention has a release layer on at least one surface of the film substrate. The release layer may be provided on only one side (only one side) of the film substrate, or may be provided on both sides. As a release film used for the manufacturing method of said optical display panel, it is preferable that the release layer is provided only in one side of the film base material.

  In the release film of the present invention, it is important that the ratio (B / A) of peel strength A and peel strength B defined below is 0.70 to 0.92.

<Peel strength A>
A test piece was prepared by laminating a release layer of the release film and an adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation; substrate thickness 25 μm / total thickness 53 μm). Is the peel strength when the adhesive tape side is peeled off at 180 °.

<Peel strength B>
The peel strength when the release film side is peeled off at 180 ° for the test piece prepared in the same manner as described above.

  The method for measuring the peel strength A and the peel strength B will be described in detail in the Examples section.

  Peel strength A represents the peel strength of the release layer itself, and is measured by peeling the adhesive tape side from the test piece to 180 °.

  The peel strength A is preferably in the range of 30 to 130 mN / 50 mm. Thereby, it is possible to suppress inconvenient problems such as the release film being peeled off from the optical film, shifted, or lifted in the transport process of the long optical film laminate, the half cut process, and the like. Moreover, by making peeling strength A into the said range, the peelability in the peeling process of a release film becomes favorable, and generation | occurrence | production of a zipping etc. can be suppressed. From the above viewpoint, the peel strength A is further preferably in the range of 40 to 120 mN / 50 mm, more preferably in the range of 50 to 110 mN / 50 mm, and particularly preferably in the range of 60 to 100 mN / 50 mm.

  The peel strength B represents the peel strength as a release film with respect to the peel strength A of the release layer itself, and is measured by peeling the release film side from the test piece to 180 °. .

  In the release film of the present invention, it is important that the ratio (B / A) between the peel strength B and the peel strength A is 0.70 to 0.92.

  By setting the ratio (B / A) to 0.92 or less, the contact pressure between the release film and the release means when the release film is released from the long optical film laminate is reduced. The mold film shavings and oligomer components are prevented from adhering to and contaminating the peeling means and its periphery. Further, by setting the ratio (B / A) to 0.92 or less, the occurrence of zipping is suppressed. From the above viewpoint, the ratio (B / A) is preferably 0.90 or less, more preferably 0.87 or less, and particularly preferably 0.85 or less.

  On the other hand, when the ratio (B / A) is smaller than 0.70, the release film may not be smoothly peeled off. Moreover, when the said ratio (B / A) becomes smaller than 0.70, a wrinkle may generate | occur | produce in the conveyance process of a long optical film laminated body. From the above viewpoint, the lower limit of the ratio (B / A) is preferably 0.73 or more, and more preferably 0.75 or more.

  As the film substrate in the release film of the present invention, a known plastic film can be used. Examples of the plastic film include polyester film, polyethylene film, polypropylene film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, Polysulfone film, polyether ether ketone film, polyether sulfone film, polyphenylene sulfide film, polyetherimide film, polyimide film, fluororesin film, polyamide film, acrylic resin film, norbornene resin film, cycloolefin resin film, etc. .

  Among the above film base materials, a polyester film is preferable from the viewpoint of being excellent in mechanical strength, heat resistance, thermal dimensional stability and chemical resistance and economical.

  The polyester in the polyester film is a general term for polymers having an ester bond as a main bond chain, and is obtained by polycondensation of an acid component and its ester with a diol component. Specific examples include polyethylene terephthalate, polypropylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, and the like. These may be copolymerized with other dicarboxylic acids and their esters or diol components as acid components or diol components. Among these, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferable in terms of transparency, dimensional stability, heat resistance, etc., and polyethylene terephthalate is particularly preferable.

  Among the polyester films, a biaxially oriented polyester film is preferable, and a biaxially oriented polyethylene terephthalate film is particularly preferable.

  In addition, since the biaxially oriented polyethylene terephthalate film can control the orientation angle, the release film using the biaxially oriented polyethylene terephthalate film as the film substrate is a polarizing plate when the optical film is a polarizing plate. It is suitable for the crossed Nicols method in which foreign matter inspection is performed on a laminate in which a release film is bonded to each other through an adhesive layer.

  Here, the crossed Nicols method is a method in which two polarizing plates are made to have a dark field with their orientation main axes orthogonal to each other, and an object to be measured is sandwiched between them and observed with transmitted light. If there are foreign matters or defects in the polarizing plate, they will appear as bright spots, so that the defect inspection can be performed.

  When the optical film is a polarizing plate, the release film preferably has a haze value in the range of 6 to 14%. If the haze value of the release film is less than 6%, the reflected light may be too strong when inspecting the polarizing plate, which may hinder the inspection. On the other hand, if the haze value exceeds 14%, the reflected light may be reflected. May become too weak and hinder inspection. The haze value of the release film is more preferably in the range of 7 to 13%, particularly preferably in the range of 8 to 12%.

  In the long optical film laminate in the present invention, one outermost surface of the long optical film laminate is constituted from the viewpoint of improving the transportability, winding property, or blocking resistance of the long optical film laminate. The surface roughness SRa of one surface of the release film (reference numeral 13a in FIG. 2a) is preferably in the range of 10 to 50 nm, more preferably in the range of 15 to 40 nm, and particularly preferably in the range of 20 to 35 nm.

  That is, the surface roughness SRa of the surface opposite to the surface on which the release layer of the release film is provided is preferably 10 to 50 nm, more preferably 15 to 40 nm, and particularly preferably 20 to 35 nm. preferable. When release layers are provided on both surfaces of the film substrate, the surface roughness SRa of at least one of the release layer surfaces is preferably in the above range.

  As described above, the release layer of the present invention is preferably provided with a release layer only on one side (only one side) of the film base. In this case, the release layer of the film base is provided. It is preferable that the surface roughness SRa of the unfinished surface falls within the above range.

  The film substrate constituting the release film of the present invention may be a single layer or a laminated structure of two or more layers. From the viewpoint of adjusting the haze value of the release film to the above range, or from the viewpoint of adjusting the surface roughness SRa of at least one surface of the release film to the above range, the film substrate has a three-layer laminated structure. It is preferable to contain particles in the surface layer.

  Here, examples of the three-layer laminated structure include a laminated structure of A layer / B layer / A layer or A layer / B layer / C layer. Here, the A layer, the B layer, and the C layer have different compositions. That is, the two A layers on both sides in the configuration of A layer / B layer / A layer are formed with the same composition, and the A layer and C layer on both sides in the configuration of A layer / B layer / C layer are formed with different compositions. Means that.

  The thicknesses of the two A layers on both sides in the configuration of A layer / B layer / A layer may be the same or different. Similarly, the thicknesses of the A layer and the C layer on both sides in the configuration of A layer / B layer / C layer may be the same or different.

  From the viewpoint of simplifying production facilities and improving productivity in the production of a film substrate, the configuration of A layer / B layer / A layer is more preferable, and the thicknesses of the two A layers on both sides in the configuration are the same. Particularly preferred.

  The thickness per layer of the A layer or C layer forming the surface layer of the film substrate is preferably in the range of 0.3 to 2.5 μm, more preferably in the range of 0.5 to 2.0 μm, and 1.0 to 2 A range of 0.0 μm is particularly preferred. The thickness of B layer can be suitably set according to the thickness of a film base material.

  Surface roughness SRa can be optimized because the surface layer (A layer or C layer) of the film substrate contains particles, and the haze value can be adjusted to a desired range by optimizing the particles contained in layer B. Can be adjusted.

  Types of particles include inorganic particles such as silica, aluminum silicate, titanium dioxide, calcium carbonate, crosslinked polystyrene resin particles, crosslinked silicone resin particles, crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, crosslinked polyester particles, and polyimide particles. And organic particles such as melamine resin particles, and one or more of these may be selected and used.

  The average particle size of the particles contained in the surface layer (A layer or C layer) of the film substrate is preferably in the range of 0.5 to 1.5 μm, more preferably in the range of 0.8 to 1.3 μm. The content of the particles is preferably in the range of 0.1 to 1.0% by mass, preferably 0.2 to 0.8% by mass with respect to 100% by mass of the total solid content per surface layer (A layer or C layer). The range of is more preferable.

  By containing the same kind of particles as above in the B layer in a range of 0.01 to 0.2% by mass with respect to 100% by mass of the total solid content of the B layer, the surface roughness SRa is kept in the above range. The haze value can be adjusted to the above range.

  Next, a method for producing a biaxially oriented polyethylene terephthalate film particularly suitable as a film substrate will be described in detail.

  As a method of incorporating particles into polyester, for example, particles were dispersed in a predetermined ratio in a form of slurry in ethylene glycol, which is a diol component, and, for example, high-precision filtration capable of collecting 95% or more of coarse particles of 3 μm or more was performed. Thereafter, this ethylene glycol slurry is added at an arbitrary stage before the completion of polyester polymerization. Here, when adding the particles, for example, it is preferable to add the water sol or alcohol sol obtained at the time of synthesis without drying, since the dispersibility of the particles is good and the generation of coarse protrusions can be suppressed. . It is also effective to mix a water slurry of particles directly with a predetermined polyester pellet, and supply the mixture to a vent type twin-screw kneading extruder to knead it into the polyester.

  The particle-containing master pellets prepared in this way and pellets substantially free of particles, etc., are mixed at a predetermined ratio, dried, then supplied to a known melt laminating extruder, and the polymer is filtered through a filter. .

  Subsequently, the sheet is extruded from a slit-shaped slit die and cooled and solidified on a casting roll to produce an unstretched film. That is, 1 to 3 extruders, 1 to 3 layers of manifolds or merging blocks (for example, a merging block having a rectangular merging section) are stacked as necessary, the sheet is extruded from the die, and cooled by a casting roll. To produce an unstretched film.

  This unstretched film is stretched at a stretching temperature of 90 to 130 ° C. so that the total stretching ratio is 2.5 to 5 times in one or more stages in the longitudinal direction and led to a tenter. From the viewpoint of suppressing the bowing phenomenon and thickness unevenness in the film longitudinal direction, the stretching temperature is preferably 100 to 120 ° C. and the total stretching ratio is preferably 3 to 4 times. From the viewpoint of preventing uneven stretching and scratches, stretching is divided into two or more stages. Preferably it is done.

  Next, the film is stretched 3 to 6 times in the width direction at a stretching temperature of 90 to 130 ° C. When the stretching temperature is lower than 90 ° C. and the stretching ratio is larger than 6 times, the film is easily broken. Therefore, it is more preferable that the stretching temperature is 100 to 120 ° C. and the stretching ratio is 4 to 5 times.

  The biaxially oriented film obtained as described above is guided to a cooling step and a heat treatment step to produce a biaxially oriented polyethylene terephthalate film.

  In the release film of the present invention, from the viewpoint of controlling the ratio (B / A) of the peel strength B and the peel strength A to a range of 0.70 to 0.92, the film substrate constituting the release film The thickness is preferably a relatively thin film. For example, when a biaxially oriented polyethylene terephthalate film is used as the film substrate, the thickness of the film is preferably less than 30 μm, more preferably less than 27 μm, and particularly preferably less than 25 μm. The lower limit thickness is preferably 13 μm or more, more preferably 15 μm or more, and particularly preferably 17 μm or more.

  The release layer in the release film of the present invention preferably contains a release agent. Any known release agent can be used as appropriate. Examples thereof include silicone resins, alkyd resins, polyolefin resins, long chain alkyl group-containing resins, fluorine resins, rubber resins, and the like, and these resins can be used alone or in combination.

  From the viewpoint of controlling the peel strength A in the range of 30 to 130 mN / 50 mm, it is preferable to use a silicone resin as a release agent.

  The silicone resin is preferably a curable silicone resin, and examples thereof include an addition reaction type, a condensation polymerization reaction type, and an ultraviolet curable type.

  Examples of the addition reaction type silicone resin include those obtained by heat-curing polydimethylsiloxane containing a terminal vinyl group and hydrogensiloxane under a platinum catalyst. Specific examples of the addition reaction type silicone resin include KS-774, KS843, KS847, KS847H and KS838 manufactured by Shin-Etsu Chemical Co., Ltd., SD7226, SD7223, SRX211, SRX345, SD7236 manufactured by Toray Dow Corning Co. SRX370, LTC750A, LTC371G, and the like.

  Examples of the polycondensation reaction type silicone resin include those obtained by heat-curing polydimethylsiloxane containing a hydroxyl group at the terminal and hydrogensiloxane using an organotin catalyst. Specific examples include SRX290 and SYLOFF23 manufactured by Toray Dow Corning Co., Ltd.

As UV curable silicone resin,
Examples of the addition reaction type for hydrosilylating vinylsiloxane in the presence of a platinum catalyst include X62-5039 and X62-5040 manufactured by Shin-Etsu Chemical Co., Ltd.
Moreover, as a radical addition type for curing a siloxane containing an alkenyl group and a siloxane containing a mercapto group using a photopolymerization catalyst, BY24-510H manufactured by Toray Dow Corning Co., Ltd., BY24-544, and the like can be given.
Further, as a cationic polymerization type in which an epoxy group is photo-opened with an onium salt initiator and cured, there are TPR6501, UV9300 and XS56-A2775 manufactured by GE Toshiba Silicone Co., Ltd.

  The thickness of the release layer is preferably in the range of 0.02 to 0.5 μm, more preferably in the range of 0.03 to 0.3 μm, and particularly preferably in the range of 0.04 to 0.2 μm.

  As a method for forming the release layer, it is formed by applying a coating composition containing the above-described release agent or the like on a film substrate by a wet coating method, and drying and curing as necessary.

  Examples of the wet coating method include a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method, a spin coating method, an extrusion coating method, and a curtain coating method.

  In the release film of the present invention, a primer layer can be provided between the film substrate and the release layer, or on the surface opposite to the release layer of the film substrate. The primer layer preferably has various functions such as an antistatic function, a function of preventing oligomer precipitation from the film substrate, and a function of enhancing adhesion between the film substrate and the release layer.

  In order to impart an antistatic function to the primer layer, the primer layer preferably contains an antistatic agent. Examples of the antistatic agent include conductive metal oxide fine particles, ionic surfactant, π-conjugated conductive polymer compound, ionic polymer compound, and siloxane antistatic agent. Alternatively, two or more kinds can be used in combination.

  Examples of the conductive metal oxide fine particles include indium tin oxide, antimony-doped tin oxide (ATO), zinc antimonate, and antimony oxide.

  Examples of the ionic surfactant include an anionic surfactant and a cationic surfactant. Specific examples of the anionic surfactant include alkylbenzene sulfonate, α-olefin sulfonate, alkane sulfonate, alkyl sulfate, polyoxyethylene alkyl ether sulfate, alkyl phosphate, and long chain fatty acid salt. , Α-sulfo fatty acid ester salts and the like. Examples of the cationic surfactant include a quaternary ammonium salt type surfactant such as a tetraalkylammonium salt and a trialkylbenzylammonium salt, and an imidazoline type surfactant.

  The π-conjugated conductive polymer compound is not particularly limited as long as it is a polymer compound whose main chain is composed of a π-conjugated system. For example, aliphatic conjugated polyacetylene, polyacene, polyazulene, aromatic conjugated polyphenylene, heterocyclic conjugated polypyrrole, polythiophene, polyisothianaphthene, heteroatom-containing polyaniline, polythienylene vinylene, mixed type Conjugated poly (phenylene vinylene), double-chain conjugated systems with multiple conjugated chains in the molecule, derivatives of these conductive polymers, and these conjugated polymer chains as saturated polymers Examples thereof include conductive composites that are grafted or block-copolymerized polymers. Among these, π-conjugated conductive polymer compounds such as polythiophene, polyaniline, and polypyrrole are more preferable.

  Examples of the ionic polymer include an anionic polymer and a cationic polymer.

  The anionic polymer can be obtained by polymerizing a monomer having an anionic group and a reactive unsaturated bond in the molecule. Examples of the anionic group include a sulfone group, a carboxyl group, a phosphoric acid group, and a salt thereof. Examples of such anionic polymers include polystyrene sulfonic acid, poly (meth) acrylic acid, and these. Salts (alkali metal salts, alkaline earth metal salts, ammonium salts).

  The cationic polymer can be obtained by polymerizing a monomer having an unsaturated bond reactive with a cationic group in the molecule. Examples of the cationic group include a polymer having a substituent such as a primary to tertiary amino group, an amide group, a quaternary ammonium salt, a phosphonium salt, and a sulfonium salt. Examples of such cationic polymers include vinylamine, allylamine, acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, and the like. These polymers are mentioned.

  In order to provide the primer layer with an adhesion enhancement function and an oligomer prevention function, the primer layer preferably contains an organosilicon compound containing an organoaluminum compound.

  Examples of organoaluminum compounds include aluminum salts such as aluminum alcoholate, naphthenic acid, stearic acid, octylic acid, benzoic acid, aluminum chelates obtained by reacting aluminum alcoholate with acetoacetate or dialkyl malonate, and organic acid salts of aluminum oxide And aluminum acetylacetonate. Among these, aluminum chelate is preferable. Specific examples include aluminum tris (acetylacetonate) and aluminum monoacetylacetonate bis (ethylacetoacetate).

  Examples of the organosilicon compound include those composed of γ-methacryloxy group-containing organoalkoxysilane, epoxy group-containing organoalkoxysilane, vinyl group-containing organoalkoxysilane, vinyl group-containing acetoxysilane, and mixtures thereof.

  The thickness of the primer layer is preferably in the range of 0.005 to 0.3 μm, more preferably in the range of 0.01 to 0.2 μm, and particularly preferably in the range of 0.02 to 0.1 μm.

  As a method for forming the primer layer, the primer composition is formed by applying a coating composition containing the above-described materials onto a film substrate by a wet coating method, and drying and curing as necessary. Examples of the wet coating method include the same methods as described above.

  Prior to laminating the release layer or primer layer on the film substrate, the film substrate can be subjected to a surface treatment. Examples of the surface treatment include chemical treatment, mechanical treatment, corona discharge treatment, flame treatment, ultraviolet irradiation treatment, high frequency treatment, glow discharge treatment, active plasma treatment, laser treatment, mixed acid treatment and ozone oxidation treatment. Among these, glow discharge treatment, ultraviolet irradiation treatment, corona discharge treatment and flame treatment are preferred, and glow discharge treatment and ultraviolet treatment are more preferred.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

  The measurement method and evaluation method in this example are shown below.

(1) Measurement of peel strength A <Preparation of test specimen for measurement>
The longitudinal direction of the roll-like product of the release film and the longitudinal direction of the roll-shaped adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation; substrate thickness 25 μm / total thickness 53 μm) are the same direction. A test specimen for measurement (longitudinal direction 20 cm × width direction 5 cm) was prepared by reciprocating and sticking the adhesive surface of the adhesive tape to the release layer surface of the release film with a rubber roller having its own weight of 5 kg.

<Measurement of peel strength>
After leaving the test specimen for 24 hours at room temperature (23 ± 2 ° C), measure the peel strength when the adhesive tape side is peeled 180 ° in the longitudinal direction at a speed of 300 mm / min with a tensile tester. did.

(2) Measurement of peel strength B The peel strength was measured in the same manner as the measurement of the peel strength A described above. However, in the measurement, the release film side was peeled off at 180 ° in the longitudinal direction.

(3) Measurement of surface roughness SRa The surface roughness SRa on both surfaces of the film substrate and the SRa on the surface opposite to the surface provided with the release layer of the release film were measured.

Measured using a three-dimensional fine surface shape measuring instrument (ET-350K manufactured by Kosaka Seisakusho), the arithmetic average roughness SRa value was determined from the obtained surface profile curve according to JIS B0601 (1994). The measurement conditions are as follows.
-X direction measurement length: 0.5 mm, X direction feed rate: 0.1 mm / second.
-Y direction feed pitch: 5 μm, Y direction line number: 40.
Cut-off: 0.25 mm.
-Contact pressure: 0.02 mN.
-Height (Z direction) magnification: 50,000 times.

(4) Measurement of Haze Value of Release Film Based on JIS K 7136 (2000), the haze value of the release film was measured using a turbidimeter “NDH-4000” manufactured by Nippon Denshoku Industries Co., Ltd. In the measurement, it is arranged so that light is incident on the surface of the release layer of the release film.

(6) Thickness of each layer Using a microsampling system (Hitachi FB-2000A), a sample for observing the cross section of the release film was measured by the FIB method (specifically, “Polymer Surface Processing” (by Iwamori Satoshi) p) .118-119)). Using a transmission electron microscope (H-9000UHRII manufactured by Hitachi), the cross section of the sample for cross section observation was observed at an acceleration voltage of 300 kV, and the thicknesses of the film substrate, the anchor layer, and the release layer were measured.

(7) Measurement of average particle diameter of particles contained in film base material A cross section of the film base material is observed with an electron microscope (approximately 20,000 to 50,000 times), and from the cross-sectional photograph,
The maximum length of each of 30 randomly selected particles was measured, and the average of these was taken as the average particle size of the particles.

[Production of film substrate]
The following biaxially oriented polyethylene terephthalate film was produced as a film substrate. First, homopolyester pellet a, calcium carbonate-containing master pellet b, and polyesters A and B using these materials, which are raw materials for the polyethylene terephthalate film, were prepared as follows.

<Preparation of homopolyester pellet a>
To dimethyl terephthalate (DMT), 1.9 moles of ethylene glycol with respect to 1 mole of DMT, 0.05 parts by weight of magnesium acetate tetrahydrate with respect to 100 parts by weight of DMT, and 0.015 parts by weight of phosphoric acid. In addition, transesterification was performed to obtain a transesterification product a. Subsequently, 0.025 parts by mass of antimony trioxide is added to 100 parts by mass of DMT, and the polycondensation reaction is performed by heating and heating to vacuum, and homopolyester pellets a having an intrinsic viscosity of 0.63 and containing substantially no particles are obtained. Obtained.

<Preparation of calcium carbonate-containing master pellet b>
Ethylene glycol containing 10% by mass of calcium carbonate with an average particle size of 1.0 μm is dispersed for one hour with a jet agitator and filtered with high accuracy through a filter with a collection efficiency of 95% of 5 μm or more to obtain an ethylene glycol slurry. Obtained. This was added to the transesterification product a prepared in the same manner as described above, followed by addition of antimony trioxide, a polycondensation reaction was carried out, and a calcium carbonate-containing master pellet having an intrinsic viscosity of 0.63 containing 1% by mass of calcium carbonate. b was obtained.

<Preparation of polyester A>
Homopolyester pellet a and calcium carbonate-containing master pellet b were mixed to obtain polyester A containing 0.5% by mass of calcium carbonate.

<Preparation of polyester B>
Homopolyester pellet a and calcium carbonate-containing master pellet b were mixed to obtain polyester B containing 0.05% by mass of calcium carbonate.

[Production of Film Base 1]
After the above polyester A and polyester B were each dried under reduced pressure at 160 ° C. for 8 hours, supplied to separate extruders, melt-extruded at 275 ° C. and filtered through a high-precision filter with a collection efficiency of 95% of 5 μm or more. In a rectangular three-layer confluence block, the layers were joined and laminated to form a three-layer laminate comprising polyester A layer / polyester B layer / polyester A layer. Thereafter, the film was cooled and solidified on a casting roll having a surface temperature of 25 ° C. by using an electrostatic application casting method through a slit die maintained at 285 ° C. to obtain an unstretched film. This unstretched film was first stretched 3.4 times in the longitudinal direction with a roll heated to 103 ° C. and a radiation heater. Subsequently, the film was stretched 4.4 times at 105 ° C. in the width direction with a tenter, the cooling temperature was set to 40 ° C., and the film temperature was cooled to 42 ° C. In this cooling step, a roll method was adopted, followed by heat treatment at 190 ° C. to obtain a long roll of biaxially oriented polyethylene terephthalate film having a three-layer laminated structure.

  The film substrate had a thickness of 19 μm, the polyester A layers on both sides had a thickness of 1.5 μm, and the polyester B layer had a thickness of 16 μm. The film substrate had a surface roughness SRa of 25 nm on both sides.

[Preparation of film substrate 2]
In the production of the film substrate 1, a film substrate 2 was produced in the same manner as the film substrate 1 except that the thickness of the polyester B layer was changed to 22 μm. The film substrate had a thickness of 25 μm, the polyester A layers on both sides had a thickness of 1.5 μm, and the polyester B layer had a thickness of 22 μm. The film substrate had a surface roughness SRa of 25 nm on both sides.

[Production of Film Base 3]
In the production of the film substrate 1, a film substrate 3 was produced in the same manner as the film substrate 1 except that the thickness of the polyester B layer was changed to 20 μm. The film substrate had a thickness of 23 μm, the polyester A layers on both sides had a thickness of 1.5 μm, and the polyester B layer had a thickness of 20 μm. The film substrate had a surface roughness SRa of 25 nm on both sides.

[Production of Film Base 4]
In the production of the film substrate 1, a film substrate 4 was produced in the same manner as the film substrate 1 except that the thickness of the polyester B layer was changed to 12 μm. The film substrate had a thickness of 15 μm, the polyester A layers on both sides had a thickness of 1.5 μm, and the polyester B layer had a thickness of 12 μm. The film substrate had a surface roughness SRa of 25 nm on both sides.

[Preparation of film substrate 5]
In the production of the film substrate 1, a film substrate 5 was produced in the same manner as the film substrate 1 except that the thickness of the polyester B layer was changed to 9 μm. The film substrate had a thickness of 12 μm, the polyester A layers on both sides had a thickness of 1.5 μm, and the polyester B layer had a thickness of 9 μm. The film substrate had a surface roughness SRa of 25 nm on both sides.

[Production of Film Base 6]
In the production of the film substrate 1, a film substrate 6 was produced in the same manner as the film substrate 1 except that the thickness of the polyester B layer was changed to 35 μm. The film substrate had a thickness of 38 μm, the polyester A layers on both sides had a thickness of 1.5 μm, and the polyester B layer had a thickness of 35 μm. The film substrate had a surface roughness SRa of 25 nm on both sides.

[Preparation of film substrate 7]
In the production of the film substrate 1, a film substrate 7 was produced in the same manner as the film substrate 1 except that the thickness of the polyester B layer was changed to 72 μm. The film substrate had a thickness of 75 μm, the polyester A layers on both sides had a thickness of 1.5 μm, and the polyester B layer had a thickness of 72 μm. The film substrate had a surface roughness SRa of 25 nm on both sides.

[Example 1]
The following anchor layer coating solution and release layer coating solution were laminated in this order on one surface of the film substrate 1 prepared above to prepare a long roll-like product of a release film.

<Anchor layer coating solution>
5 parts by mass of an epoxy group-containing organosilicon compound (“BY24-846B” from Toray Dow Corning), 5 parts by mass of a methacryl group-containing organosilicon compound (“OFS-6030” from Toray Dow Corning), It was prepared by mixing 1 part by mass of an aluminum chelate (“BY24-846E” from Toray Dow Corning Co., Ltd.) and 100 parts by mass of a toluene / MEK (50/50) mixture.

<Release layer coating solution>
10 parts by mass of addition reaction type curable silicone resin (“KS847H” from Shin-Etsu Chemical Co., Ltd.), 0.05 part by mass of curing agent (platinum catalyst; “PL-50T” from Shin-Etsu Chemical Co., Ltd.), toluene / MEK (50/50) mixture was prepared by mixing 100 parts by mass.

<Lamination of anchor layer and release layer>
The primer layer coating liquid is applied to one side of the film substrate 1 with a first gravure coater, and after removing the solvent for 3 seconds in an oven at 125 ° C., continuously with a second gravure roll, It was applied and subjected to solvent removal and curing reaction in a 150 ° C. oven for 12 seconds to obtain a release film. The thickness of the anchor layer after drying was 0.05 μm, and the thickness of the release layer was 0.08 μm.

[Examples 2 to 4 and Comparative Examples 1 to 3]
In Example 1, each release film was produced like Example 1 except having changed the film base material into the film base material shown in Table 1.

[Evaluation]
Table 1 shows the results of measurement and evaluation of the release films prepared in the above Examples and Comparative Examples.

  Since Examples 1-4 which are the release films of this invention have ratio (B / A) of peeling strength B and peeling strength A in the range of 0.76-0.86, the peeling means of a release film And the problem that the periphery of the adhesive layer is contaminated and the problem that peeling stripes (traces) are generated on the surface of the pressure-sensitive adhesive layer due to zipping are suppressed.

  On the other hand, in Comparative Example 1, since the ratio (B / A) is 0.68 which is less than 0.70, the release film is not peeled off smoothly, and Comparative Examples 2 and 3 have the ratio (B / A). Is 0.95 or 1.14, which is larger than 0.92, and the peeling means and its surroundings are contaminated.

DESCRIPTION OF SYMBOLS 1 Long optical film laminated body 2 Optical display element 3 Peeling means 4 A pair of bonding roller 5 Optical display panel 10 Optical film 11 with an adhesive layer Optical film 12 Adhesive layer 13 Release film

Claims (8)

A release film having a release layer on at least one surface of a film substrate, wherein the ratio (B / A) of peel strength A and peel strength B defined below is 0.70 to 0.92. A release film characterized by being.
<Peel strength A>
A test piece was prepared by laminating a release layer of the release film and an adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation; substrate thickness 25 μm / total thickness 53 μm). Is the peel strength when the adhesive tape side is peeled off at 180 °.
<Peel strength B>
The peel strength when the release film side is peeled off at 180 ° for the test piece prepared in the same manner as described above.   The release film according to claim 1, wherein the peel strength A is in a range of 30 to 130 mN / 50 mm.   The release film according to claim 1 or 2, wherein the release film has a haze value of 6 to 14%.   The release film in any one of Claims 1-3 whose surface roughness SRa of the surface on the opposite side to the surface which has a release layer of a release film is the range of 10-50 nm.   The release film according to any one of claims 1 to 4, wherein the film substrate is a biaxially oriented polyester film.   The release film according to claim 5, wherein the film substrate has a three-layer laminated structure of A layer / B layer / A layer or A layer / B layer / C layer.   The release film in any one of Claims 1-6 which has an anchor layer between a film base material and a release layer. The release film according to any one of claims 1 to 7, which is used in a method for producing the following optical display panel.
<Method for manufacturing optical display panel>
The release film is peeled off at a peeling angle (θ) of 100 ° or more by a peeling means from the long optical film laminate in which the pressure-sensitive adhesive layer and the release film are laminated in this order on the optical film, and then passed through the pressure-sensitive adhesive layer. The manufacturing method which bonds an optical film and an optical display element.

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