JP2017181789A - Removal method of release film and manufacturing method of optical display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, in a rectangular optical film including a release film, a first adhesive layer, a polarizing film and a surface protective film laminated in this order, a method allowing easy removal of the release film even if the polarizing film used is thin.SOLUTION: A method is for removing, from a rectangular optical film including a release film, a first adhesive layer, a polarizing film and a surface protective film laminated in this order, the release film, while pressing an adhesive member to the release film side of the optical film. The polarizing film has thickness of 60 μm or less. The pressing is performed so as not to include an apex of the optical film in an initial pressing part where the release film is pressed first by the adhesive member.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for peeling a release film from a rectangular optical film in which a release film, a first pressure-sensitive adhesive layer, a polarizing film, and a surface protective film are laminated in this order.
Moreover, this invention relates to the manufacturing method of the optical display panel using the peeling method of the said release film.

  Generally, a polarizing film is used as a polarizing film with an adhesive layer in which an adhesive layer is provided on one surface for adhering to an optical cell such as a liquid crystal cell. Usually, a release film is temporarily attached to the pressure-sensitive adhesive layer until it is applied for bonding. On the other hand, a surface protective film is temporarily attached to the other surface of the polarizing film. Such a polarizing film with a pressure-sensitive adhesive layer having a release film and a surface protective film is applied to an optical display panel. In this case, first, the release film is peeled from the polarizing film with a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer exposed is bonded to the optical cell. The surface protective film is directly bonded to the bonded polarizing film with the pressure-sensitive adhesive layer.

  The bonding is, for example, a method in which the pressure-sensitive adhesive layer-attached polarizing film is fed out from a wound body and bonded to the surface of the optical cell via the pressure-sensitive adhesive layer exposed by peeling off the release film (hereinafter referred to as the adhesive layer). Also referred to as “roll-to-panel method.” Patent Document 1). Also, there is a method in which a rectangular polarizing film with an adhesive layer is attached to an optical cell via an adhesive layer that is exposed by peeling the release film (hereinafter also referred to as “sheet-to-panel method”). is there. In the sheet-to-panel method, for example, the surface protective film can be peeled off with an adhesive tape or the like (see, for example, Patent Documents 2 and 3).

  On the other hand, image display devices such as liquid crystal display devices are becoming thinner, and the polarizing film is also required to be thinner. Therefore, thinning is also performed for the polarizer (Patent Document 4). Moreover, thinning of a polarizing film can be performed by providing a protective film only on one side of the polarizer and using a single protective polarizing film that is not provided with a protective film on the other side. The single-protective polarizing film can be a thin type because the protective film is less than one protective polarizing film provided with protective films on both sides of the polarizer.

Japanese Patent No. 4406043 JP-A-5-273413 JP-A-9-114384 Japanese Patent No. 4751481

  When releasing the release film from the polarizing film with the pressure-sensitive adhesive layer having the release film and the surface protective film, the release film is usually in a state where the surface protective film side of the polarizing film with the pressure-sensitive adhesive layer is fixed. Is peeled off. However, in recent years, there has been an increasing demand for a mode in which the surface protective film can be easily peeled without any adhesive residue, and the peel strength of the surface protective film has been further reduced. Originally, from the viewpoint of the peeling order, the release film that is peeled first is designed so that the peeling force is sufficiently small (easy to peel) compared to the surface protective film that is peeled later. It is desirable. However, in recent years, the polarizing film with the pressure-sensitive adhesive layer is designed so that the peel strength of the surface protective film is not sufficiently large or the peel strength of the surface protective film is smaller than the peel strength of the release film. It was newly discovered that it was proposed. Therefore, at the time of peeling of a release film, the problem which peeling will arise in the interface of a polarizing film and a surface protective film instead of the interface of a release film and an adhesive layer has arisen. The problem can be solved, for example, by making the peeling force of the surface protective film and the peeling force of the release film substantially the same. However, the release film is required to have a peeling force that exceeds a predetermined level in order to ensure the adhesion between the polarizing film and the optical cell. Therefore, the release film is designed to have the same release force as that of the surface protective film. In such a case, the adhesion between the polarizing film and the optical cell is reduced, or the demand for reducing the peeling force of the surface protective film cannot be met. Moreover, the peeling method of patent document 2, 3 is applied to a surface protection film, and its utilization for the peeling method of the said release film is difficult. In particular, the above problem is apparent when a release film is peeled from a sheet-like polarizing film with a pressure-sensitive adhesive layer having a thin polarizing film of a predetermined thickness or less (for example, a thickness of 60 μm or less) in a sheet-to-panel system. I found out that

  The present invention is a rectangular optical film in which a release film, a first pressure-sensitive adhesive layer, a polarizing film and a surface protective film are laminated in this order, and even when a thin polarizing film is used, It aims at providing the method which can peel a mold film easily.

  Another object of the present invention is to provide a method for producing an optical display panel using the release film peeling method.

  As a result of intensive studies, the inventors of the present application have found that the above-described problems can be solved by the following optical film and the like, and have reached the present invention.

That is, the present invention presses an adhesive member from a rectangular optical film in which a release film, a first pressure-sensitive adhesive layer, a polarizing film, and a surface protective film are laminated in this order to the release film side of the optical film. A method of peeling the release film,
The polarizing film has a thickness of 60 μm or less,
It is related with the peeling method characterized by performing the said press so that the vertex of the said optical film may not be included in the initial press part which presses the said release film initially with the said adhesive member.

  In the said peeling method, this invention is suitable when the peeling force (1) of the said release film is larger than the peeling force (2) of the said surface protection film.

  In the peeling method, an adhesive roll having an adhesive member on a part of the roll surface can be used as the adhesive member. The adhesive member of the adhesive roll is preferably provided in a spiral shape on the roll surface.

  In the peeling method, the initial pressing portion of the pressure-sensitive adhesive member is in the vicinity of a vertex portion that does not include the vertex portion of the optical film, and the direction in which the release film is peeled is a diagonal direction of the optical film. It is preferable.

  The said peeling method is applied suitably when the said polarizing film has a polarizer whose thickness is 10 micrometers or less. Moreover, the said optical film is applied suitably when the said polarizing film is a piece protection polarizing film which has a protection film only in the single side | surface of a polarizer.

The present invention is a rectangular optical film in which a release film, a first pressure-sensitive adhesive layer, a polarizing film and a surface protective film are laminated in this order,
Preparing the polarizing film having a thickness of 60 μm or less (1),
Step (2) of peeling the release film from the optical film by the peeling method described above, and
It is related with the manufacturing method of the optical display panel which has the process (3) of bonding the 1st adhesive layer side of the said optical film from which the said release film was peeled off to the one surface of an optical cell.

  In the method for manufacturing an optical display panel, a liquid crystal cell or an organic EL cell can be used as the optical cell.

  In Patent Documents 2 and 3, the surface protective film is peeled off by pulling up on the surface protective film of the polarizing film (rectangular object) while pressing the adhesive member. Moreover, in patent document 2, 3, in order to peel off a surface protective film easily, it pulls up, pressing to the initial press part of an adhesive member so that the vertex of the said rectangular object may be included (henceforth this " Edge peeling "). In edge peeling, it is considered that peeling related to the surface protective film gradually spreads in the width direction of the adhesive member from the top, and the peeling force of the surface protective film depends on the length of the surface protective film pulled up by peeling. It is thought that it will gradually increase. When the surface protective film is provided on both surfaces as in Patent Documents 2 and 3, edge peeling can be suitably applied.

  However, like the rectangular optical film of the present invention (polarizing film with a pressure-sensitive adhesive layer having a release film and a surface protective film), it has a surface protective film and a release film that can be peeled on both sides of the polarizing film, And when the thickness of a polarizing film is small (it is 60 micrometers or less), especially when the peeling force of a surface protection film is small compared with the peeling force of a release film, the said edge peeling is performed with respect to a release film. And preferentially, peeling occurs at the interface with weak peeling force (interface between the polarizing film and the surface protective film).

  Therefore, in the peeling method of the present invention, when releasing the film from the optical film, while pressing the initial pressing portion of the adhesive member so as not to include the top of the optical film, It is pulled up and peeled (hereinafter referred to as “side peeling”). In the side peeling, the peeling of the release film starts from a place other than the apex, and then the apex is peeled off (trigger peeling). Therefore, when the apex is peeled off, the apparent elastic modulus of the release film is obtained. Becomes higher and the peeling force becomes higher than edge peeling. As a result, the interface close to the release film due to the increase in the apparent elastic modulus of the release film, there is an interface that is easy to peel off in the optical film, rather than the interface between the polarizing film and the surface protection film, It is considered that peeling at the interface between the release film and the first pressure-sensitive adhesive layer could be performed. As a result, even when the thickness of the polarizing film is 60 μm or less and the waist (elastic modulus) is weak (further, the peeling force of the surface protective film is smaller than the peeling force of the release film), the polarizing film In the sheet-to-panel method, the release film can be easily peeled off from the rectangular optical film without causing peeling at the interface between the surface protective film and the surface protective film.

It is a cross-sectional schematic diagram of the optical film of a rectangular state. Cross-sectional schematic diagram of an optical film in a rectangular state according to another embodiment It is an example of the graph which shows the relationship between the peeling length and peeling force in edge peeling and side peeling. It is a perspective view which shows an example of the adhesive roll used for the peeling method of this invention. It is a perspective view which shows an example of the initial stage press of the peeling method of this invention. It is a perspective view which shows an outline n example of the peeling method of this invention.

  The peeling method of the present invention will be described below with reference to the drawings. 1 and 2 are schematic cross-sectional views of an optical film F that is a target of the peeling method of the present invention. The optical film F has a configuration in which a release film 3, a first pressure-sensitive adhesive layer 2, a polarizing film 1, and a surface protective film 4 are laminated in this order.

  In FIG. 2, the case where the polarizing film 1 is the piece protection polarizing film 1 'which has the protection film 1b only on the one side of the polarizer 1a is shown. In FIG. 2, the piece protective polarizing film 1 ′ is illustrated as having a first pressure-sensitive adhesive layer on the polarizer 1 a side, but the piece protective polarizing film 1 ′ is first on the protective film 1 b side. It can also arrange | position so that it may have an adhesive layer. Moreover, as the polarizing film 1, both the protective polarizing films which have the protective film 1b on both sides of the polarizer 1a can be used.

  FIG. 2 shows a case where the surface protection film 4 has a base film 41 and a second pressure-sensitive adhesive layer 42. In FIG. 2, the second pressure-sensitive adhesive layer 42 side of the surface protective film 4 is bonded to the polarizing film 1. FIG. 1 shows a case where the surface protective film 4 is a self-adhesive film.

  Both the release film 3 and the surface protective film 4 are finally peeled off, and the release force (1) of the release film 3 and the peel force (2) of the surface protective film 4 are respectively It is preferable to design for a suitable peeling force. The peel force (1) is the peel force of the release film 3 with respect to the first pressure-sensitive adhesive layer 2, and the peel force (2) is the peel force of the surface protective film 4 with respect to the polarizing film 1.

  The peeling force (1) is preferably 0.03 N / 25 mm or more from the viewpoint of preventing end lifting during processing. Furthermore, it is preferably 0.05 to 0.5 N / 25 mm, and more preferably 0.1 to 0.3 N / 25 mm. Further, the peeling force (2) is preferably 0.2 N / 25 mm or less, more preferably 0.01 to 0.1 N / 25 mm, and further preferably 0.01 from the viewpoint of simple peeling. It is preferable that it is -0.05N / 25mm.

  The optical film F of the present invention is suitably applied to a case where the release force (1) of the release film 3 is larger than the release force (2) of the surface protective film 4. In the optical film F of the present invention, the value {peeling force (1) / peeling force (2)} of the peeling force (1) with respect to the peeling force (2) is 1.1 times or more. It is suitable when it is 5 times or more.

<Polarizing film>
In the present invention, a polarizing film having a thickness (total thickness) of 60 μm or less is used. The thickness of the polarizing film may be 55 μm or less, further 50 μm or less from the viewpoint of thinning. In the sheet-to-panel method using the polarizing film, when the release film is peeled off, the peeling film is likely to be peeled off at the interface between the polarizing film and the surface protective film instead of the interface between the release film and the pressure-sensitive adhesive layer. Application to the polarizing film is more preferable. As the configuration of the polarizing film, for example, (1) a configuration in which protective films are laminated in this order on both sides of the polarizer (both protective polarizing films), and (2) a protective film is laminated only on one side of the polarizer. Structure (single protective polarizing film).

≪Polarizer≫
A polarizer using a polyvinyl alcohol-based resin is used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

  The thickness of the polarizer is preferably 10 μm or less from the viewpoint of thinning, more preferably 8 μm or less, further 7 μm or less, and further preferably 6 μm or less. On the other hand, the thickness of the polarizer is preferably 2 μm or more, and more preferably 3 μm or more. Such a thin polarizer has less thickness unevenness, excellent visibility, and less dimensional change, and therefore excellent durability against thermal shock. On the other hand, since a polarizing film including a polarizer having a thickness of 10 μm or less has a significantly low elasticity (elastic modulus), the release film and the pressure-sensitive adhesive layer are peeled off when the release film is peeled off in the sheet-to-panel method. Peeling is particularly likely to occur at the interface between the polarizing film and the surface protective film rather than at the interface of the present invention, and the present invention is particularly suitable for the polarizing film.

As a thin polarizer, typically,
Patent No. 4751486,
Japanese Patent No. 4751481,
Patent No. 4815544,
Patent No. 5048120,
International Publication No. 2014/077599 pamphlet,
International Publication No. 2014/077636 Pamphlet,
And the thin polarizers obtained from the production methods described therein.

The polarizer has an optical property represented by the following formula: P> − (10 ^0.929T-42.4 −1) × 100 (where T <42.3). Or it is preferable to be comprised so that the conditions of P> = 99.9 (however, T> = 42.3) may be satisfied. A polarizer configured so as to satisfy the above-described conditions uniquely has performance required as a display for a liquid crystal television using a large display element. Specifically, the contrast ratio is 1000: 1 or more and the maximum luminance is 500 cd / m ² or more. As other uses, for example, it is bonded to the viewing side of the organic EL cell.

  As the thin polarizer, among the production methods including the step of stretching in the state of a laminate and the step of dyeing, Patent No. 4751486, Patent, in that it can be stretched at a high magnification and the polarization performance can be improved. What is obtained by the manufacturing method including the process of extending | stretching in a boric-acid aqueous solution as described in the 4751481 specification and the patent 4815544 specification is preferable, and it describes especially in the patent 4751481 specification and the patent 4815544 specification. What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric-acid aqueous solution which has this is preferable. These thin polarizers can be obtained by a production method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin base material in a laminated state and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching by being supported by the stretching resin substrate.

≪Protective film≫
As the material constituting the protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like can also be mentioned as examples of the polymer forming the protective film. These protective films are usually bonded to the polarizer by an adhesive layer.

  In addition, 1 or more types of arbitrary appropriate additives may be contained in the protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When content of the said thermoplastic resin in a protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  As the protective film, a retardation film, a brightness enhancement film, a diffusion film, and the like can also be used.

  The thickness of the protective film can be determined as appropriate, but generally it is preferably 5 to 50 μm, more preferably 5 to 45 μm, from the viewpoints of workability such as strength and handleability, and thin layer properties. Is preferred.

  A functional layer such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer or an antiglare layer can be provided on the surface of the protective film to which the polarizer is not adhered. In addition, the hard coat layer, the antireflection layer, the antisticking layer, the diffusion layer, the antiglare layer, and other functional layers can be provided on the protective film itself, or can be provided separately from the protective film. it can.

<Intervening layer>
The protective film and the polarizer are laminated via an intervening layer such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer). At this time, it is desirable that the both are laminated without an air gap by an intervening layer. In addition, also in FIG. 2, the intervening layer of the polarizer 1a and the protective film 1b is not shown.

  The adhesive layer is formed of an adhesive. The type of the adhesive is not particularly limited, and various types can be used. The adhesive layer is not particularly limited as long as it is optically transparent. Examples of the adhesive include water-based, solvent-based, hot-melt-based, active energy ray-curable types, and the like. Or an active energy ray hardening-type adhesive agent is suitable.

  Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, and a water-based polyester. The water-based adhesive is usually used as an adhesive made of an aqueous solution, and usually contains 0.5 to 60% by weight of a solid content.

  The active energy ray curable adhesive is an adhesive that cures by an active energy ray such as an electron beam or ultraviolet rays (radical curable type, cationic curable type), for example, in an electron beam curable type or an ultraviolet curable type. Can be used. As the active energy ray curable adhesive, for example, a photo radical curable adhesive can be used. When the photo radical curable active energy ray curable adhesive is used as an ultraviolet curable adhesive, the adhesive contains a radical polymerizable compound and a photo polymerization initiator.

  The adhesive coating method is appropriately selected depending on the viscosity of the adhesive and the target thickness. Examples of coating methods include reverse coaters, gravure coaters (direct, reverse and offset), bar reverse coaters, roll coaters, die coaters, bar coaters, rod coaters and the like. In addition, for coating, a method such as a dapping method can be appropriately used.

  Moreover, when using an aqueous adhesive etc., it is preferable to apply the adhesive so that the thickness of the finally formed adhesive layer is 30 to 300 nm. The thickness of the adhesive layer is more preferably 60 to 150 nm. On the other hand, when an active energy ray-curable adhesive is used, it is preferable that the thickness of the adhesive layer is 0.2 to 20 μm.

  In addition, in laminating | stacking a polarizer and a protective film, an easily bonding layer can be provided between a protective film and an adhesive bond layer. The easy adhesion layer can be formed of, for example, various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins can be used alone or in combination of two or more. Moreover, you may add another additive for formation of an easily bonding layer. Specifically, a stabilizer such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat resistance stabilizer may be used.

  The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive. Various pressure-sensitive adhesives can be used as the pressure-sensitive adhesive, such as rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, polyvinylpyrrolidone-based pressure-sensitive adhesives, Examples include acrylamide-based adhesives and cellulose-based adhesives. An adhesive base polymer is selected according to the type of the adhesive. Among the pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used because they are excellent in optical transparency, exhibit appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and are excellent in weather resistance and heat resistance. The

  The undercoat layer (primer layer) is formed in order to improve the adhesion between the polarizer and the protective film. The material constituting the primer layer is not particularly limited as long as the material exhibits a certain degree of strong adhesion to both the base film and the polyvinyl alcohol-based resin layer. For example, a thermoplastic resin excellent in transparency, thermal stability, stretchability, etc. is used. Examples of the thermoplastic resin include an acrylic resin, a polyolefin resin, a polyester resin, a polyvinyl alcohol resin, or a mixture thereof.

<First adhesive layer>
An appropriate pressure-sensitive adhesive can be used for forming the first pressure-sensitive adhesive layer, and the type thereof is not particularly limited. Adhesives include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, Examples thereof include cellulose-based pressure-sensitive adhesives.

  Among these pressure-sensitive adhesives, those having excellent optical transparency, suitable wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used as one exhibiting such characteristics.

  As a method for forming the first pressure-sensitive adhesive layer, for example, the pressure-sensitive adhesive is applied to a release film (separator or the like) from which the pressure-sensitive adhesive has been peeled off, and after removing the polymerization solvent and the like to form a pressure-sensitive adhesive layer, a polarizing film Or a method of applying the pressure-sensitive adhesive to a polarizing film and drying and removing the polymerization solvent to form a pressure-sensitive adhesive layer on the polarizer. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

  As the release film subjected to the release treatment, a silicone release liner is preferably used. In the step of forming the pressure-sensitive adhesive layer by applying and drying the pressure-sensitive adhesive of the present invention on such a liner, an appropriate method may be adopted as appropriate according to the purpose. Preferably, a method of heating and drying the coating film is used. The heat drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained.

  As the drying time, an appropriate time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

  Various methods are used as a method of forming the pressure-sensitive adhesive layer. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  The thickness in particular of an adhesive layer is not restrict | limited, For example, it is about 1-100 micrometers. Preferably, it is 2-50 micrometers, More preferably, it is 2-40 micrometers, More preferably, it is 5-35 micrometers.

<Release film>
The release film protects the first pressure-sensitive adhesive layer until it is practically used. Examples of the constituent material of the release film include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. However, a plastic film is preferably used from the viewpoint of excellent surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The release film has a thickness of usually 5 to 200 μm, preferably about 5 to 100 μm. For the release film, if necessary, release and antifouling treatment with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, silica powder, etc., coating type, kneading type, An antistatic treatment such as a vapor deposition type can also be performed. In particular, the release property from the first pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment on the surface of the release film.

<Surface protection film>
The surface protective film is provided on one side of the polarizing film (the side on which the first pressure-sensitive adhesive layer is not laminated) in the optical film, and protects the polarizing film.

  As the base film of the surface protective film, a film material having isotropic property or close to isotropic property is selected from the viewpoints of inspection property and manageability. Examples of film materials include polyester resins such as polyethylene terephthalate film, cellulose resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, and the like. Examples thereof include transparent polymers such as resins. Of these, polyester resins are preferred. The base film can be used as a laminate of one kind or two or more kinds of film materials, and a stretched product of the film can also be used. The thickness of the base film is generally 500 μm or less, preferably 10 to 200 μm.

  As the surface protective film, the base film can be used as a self-adhesive film, and a film having the base film and the second pressure-sensitive adhesive layer can be used. It is preferable to use a surface protective film having a second pressure-sensitive adhesive layer from the viewpoint of protecting the polarizing film.

  The second pressure-sensitive adhesive layer used for laminating the surface protective film has, for example, a (meth) acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as a base polymer. An adhesive can be appropriately selected and used. From the viewpoints of transparency, weather resistance, heat resistance and the like, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable. The thickness (dry film thickness) of the second pressure-sensitive adhesive layer is determined according to the required adhesive force. Usually, it is about 1-100 micrometers, Preferably it is 5-50 micrometers.

  In addition, a release treatment layer is provided on the surface protective film (on the opposite side of the surface when the second pressure-sensitive adhesive layer is provided) using a low adhesive material such as silicone treatment, long-chain alkyl treatment, or fluorine treatment. Can do. The thickness of the surface protective film is the total thickness of the base film, the second pressure-sensitive adhesive layer, and the release treatment layer.

<Release of release film>
The optical film F is prepared as a rectangular object having a predetermined shape (step (1)). The rectangular object having the predetermined shape is appropriately designed according to the application to which the optical film F is applied.

  In the peeling method of the present invention, the release film 3 is peeled by pulling up the release film 3 while pressing the adhesive member a against the release film 3 side of the optical film F. The adhesive member a performs the pressing so that the initial pressing portion that first presses the release film 3 does not include the vertex t of the optical film F (rectangular object), and performs the peeling (side peeling). Do. In addition, various means can be employ | adopted suitably for the press of the said adhesive member a, positioning to an initial stage press part, raising the release film 3, etc.

  FIG. 3 is an example of a graph showing the relationship between the movement distance (peeling length: 10 mm) and the peeling force (N / 50 mm) in edge peeling and side peeling when peeling the release film 3 from the optical film F. . Specifically, FIG. 3 is data obtained using a free-angle type adhesive peeling analyzer (manufactured by Kyowa Interface Science Co., Ltd.) under the condition of a 90-degree peel peeling speed of 5 m / mm. As can be seen from FIG. 3, in the edge peeling, the moving distance is increased and the peeling force is increased. On the other hand, it can be seen that in the side peeling, the initial peeling force is larger than that of the edge peeling and has a peak of trigger peeling.

  Examples of the adhesive member a include an adhesive tape and an adhesive roll. As the adhesive member a, one having an adhesive force larger than the peeling force (1) of the release film 3 is used.

  When an adhesive tape is used as the adhesive member a, a known peeling roll can be combined. For example, while applying tension to the pressure-sensitive adhesive tape with a peeling roll, the pressure-sensitive adhesive film is pressed to a place other than the apex t of the optical film F (the surface of the release film 3), and on the other hand, the pressure-sensitive adhesive tape is pulled up, Can be peeled off.

  Moreover, as the adhesive roll R used as the adhesive member a, for example, as shown in FIG. 4, one in which the adhesive member a is provided on a part of the surface of the roll r can be used. The adhesive roll R has an adhesive member a in part, and does not have the adhesive member a in other locations b.

  The pressure-sensitive adhesive roll R is preferable in terms of handling large panels and automation. The pressure-sensitive adhesive roll R can form the pressure-sensitive adhesive member a by, for example, winding a double-sided pressure-sensitive adhesive tape with a gap (b) between part of the surface of the roll r. The roll diameter of the roll r is preferably 5 to 100 mm from the viewpoint of reducing the weight and securing a stable contact surface in the width direction. In addition, the adhesive member R in the adhesive roll R can be provided in a plurality with a predetermined width (preferably 3 to 50 mm) on the surface of the roll r, and can be provided in a spiral shape with a predetermined width. ) Is preferably provided in a spiral shape from the viewpoint of simplicity in adsorption / desorption.

  The pressure-sensitive adhesive roll R is pressed against a place other than the vertex t of the optical film F (the surface of the release film 3), and on the other hand, by rotating the pressure-sensitive adhesive roll R, pulling up the release film 3 together with the pressure-sensitive adhesive member a. The release film 3 can be peeled off. When the initial pressing portion by the adhesive roll R is the apex portion of the optical film F, a location b that does not have the adhesive member a is arranged at the apex t of the optical film F.

  FIG. 5 is a perspective view showing an example of the initial pressing portion of the peeling method of the present invention. In FIG. 5, an adhesive roll R is used as the adhesive member a. FIG. 5 is an enlarged view showing a state where the adhesive roll R is initially pressed near the apex of the release film 3 of the optical film F (rectangular object). In FIG. 5, in the adhesive roll R, the location b that does not have the adhesive member a is arranged to be the apex t.

  FIG. 6 shows a state in which a part of the release film 3 is pulled up from the optical film F while pressing the release film 3 by the adhesive roll R by rotating the adhesive roll R in the direction of the arrow.

  In addition, as shown in FIG. 6, the said optical film F is installed on the plane base B so that the surface protection film 4 side may become a lower side. When the release film 3 is peeled off, the optical film F can be carried out by fixing the surface protective film 4 side by, for example, adsorption or double-sided tape. The release film 3 can be wound up in the direction of the arrow.

  The peeling of the release film 3 by pulling up the adhesive member a is not particularly limited as long as the peeling is performed by the side peeling, but the pulling direction of the adhesive member a (the peeling direction of the release film 3) is stable peeling. From this point of view, it is preferable to carry out so as to be in the diagonal direction of the optical film F (rectangular object). Moreover, although the peeling angle of a release film is 90-180 degrees, it is not specifically limited. The peeling speed is generally 0.2 to 10 m / min, but is appropriately adjusted from the viewpoint of apparatus specifications and workability (tact).

<Manufacture of optical display panel>
The optical film (optical film with a pressure-sensitive adhesive layer having a surface protective film) from which the release film has been peeled off by the above-described step (1) and then the above-described peeling step (2) of the present invention is obtained by the step (3). Affix to one side of the cell. In the step (3), the first pressure-sensitive adhesive layer side of the optical film is bonded to the optical film to produce an optical display panel.

<Other optical layers>
The optical film of the present invention can be used by being laminated with other optical layers in practical use. The optical layer is not particularly limited, but for example, a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), a viewing angle compensation film, and a brightness enhancement film One layer or two or more optical layers that may be used for forming the above may be used.

  The optical film in which the optical layer is laminated can also be formed by a method of laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that it is excellent in assembling work and can improve the manufacturing process of a liquid crystal display device or the like. For the lamination, an appropriate adhesive means such as a pressure-sensitive adhesive layer can be used. When adhering the polarizing film with the pressure-sensitive adhesive layer and other optical films, their optical axes can be arranged at an appropriate angle depending on the intended retardation characteristics and the like.

<Optical cell>
(Liquid crystal cell, liquid crystal display panel)
The liquid crystal cell has a structure in which a liquid crystal layer is sealed between a pair of substrates (a first substrate (viewing side surface) Pa and a second substrate (back surface) Pb) disposed to face each other. Although any type of liquid crystal cell can be used, it is preferable to use a vertical alignment (VA) mode or in-plane switching (IPS) mode liquid crystal cell in order to achieve high contrast. A liquid crystal display panel has a polarizing film bonded to one or both sides of a liquid crystal cell, and a drive circuit is incorporated as necessary.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical film of this invention can be installed in the one side or both sides of a liquid crystal cell. When the optical films of the present invention are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

(Organic EL cell, organic EL display panel)
An organic EL cell as another optical cell has a configuration in which an electroluminescent layer is sandwiched between a pair of electrodes. As the organic EL cell, for example, an arbitrary type such as a top emission method, a bottom emission method, a double emission method, or the like can be used. In the organic EL display panel, the optical film (polarizing film) of the present invention is bonded to the organic EL cell together with the retardation film, and a drive circuit is incorporated as necessary.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples shown below. In addition, all the parts and% in each example are based on weight. The room temperature standing conditions not specifically defined below are all 23 ° C. and 65% RH.

<Preparation of polarizing film>
(Production of polarizer)
One side of an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption of 0.75% and Tg of 75 ° C. is subjected to corona treatment. Alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd. An aqueous solution containing 9: 1 ratio of the trade name “Gosefimer Z200”) was applied and dried at 25 ° C. to form a PVA-based resin layer having a thickness of 11 μm, thereby preparing a laminate.
The obtained laminate was uniaxially stretched in the longitudinal direction (longitudinal direction) 2.0 times between rolls having different peripheral speeds in an oven at 120 ° C. (air-assisted stretching process).
Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Subsequently, it was immersed in a dyeing bath having a liquid temperature of 30 ° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was blended with 100 parts by weight of water, and immersed in an aqueous iodine solution obtained by blending 1.0 part by weight of potassium iodide (dyeing treatment). .
Subsequently, it was immersed for 30 seconds in a crosslinking bath having a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (Crosslinking treatment).
Thereafter, the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ° C. However, uniaxial stretching was performed between rolls having different peripheral speeds in the longitudinal direction (longitudinal direction) so that the total stretching ratio was 5.5 times (in-water stretching treatment).
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. (cleaning treatment).
As a result, an optical film laminate including a polarizer having a thickness of 5 μm was obtained.

(Protective film)
Protective film: A (meth) acrylic resin film having a lactone ring structure with a thickness of 40 μm was subjected to corona treatment on the easy adhesion treated surface.

(Adhesive applied to protective film)
40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholine (ACMO) and 3 parts by weight of a photoinitiator “IRGACURE 819” (manufactured by BASF) were mixed to prepare an ultraviolet curable adhesive.

<Production of single-protective polarizing film>
The protective film is bonded to the surface of the polarizer 8 of the optical film laminate so that the thickness of the adhesive layer after curing the ultraviolet curable adhesive is 1 μm. As above, the adhesive was cured by irradiating ultraviolet rays. Ultraviolet irradiation is performed using a gallium-filled metal halide lamp, an irradiation device: Fusion UV Systems, Inc. Light HAMMER 10, Inc., bulb: V bulb, peak illuminance: 1600 mW / cm ² , integrated dose 1000 / mJ / cm ² (wavelength 380 to 440 nm) ), And the illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell. Subsequently, the amorphous PET base material was peeled off to produce a piece protective polarizing film A using a thin polarizer. The optical properties of the obtained piece-protecting polarizing film A were a single transmittance of 42.8% and a degree of polarization of 99.99%. The obtained piece-protecting polarizing film has a thickness of 46 μm.

<Preparation of adhesive>
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 100 parts of butyl acrylate, 3 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate and 2,2′-azobisisobutyrate A solution was prepared by adding 0.3 parts of ronitrile with ethyl acetate. Next, the solution was stirred while blowing nitrogen gas and reacted at 55 ° C. for 8 hours to obtain a solution containing an acrylic polymer having a weight average molecular weight of 2.2 million. Furthermore, the acrylic polymer solution which added ethyl acetate to the solution containing this acrylic polymer and adjusted solid content concentration to 30% was obtained.

  As a cross-linking agent, 100 parts by weight of the solid content of the acrylic polymer solution is a cross-linking agent mainly composed of a compound having an isocyanate group of 0.5 part (trade name “Coronate L” manufactured by Nippon Polyurethane Co., Ltd.). And 0.075 parts of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KMB-403”) as a silane coupling agent in this order, Was prepared.

<Lamination of surface protective film>
A surface protective film was provided on the protective film side of the piece protective polarizing film. As the surface protective film, a polyester resin film (base film) having a thickness of 38 μm or 75 μm manufactured by “Nitto Denko Corporation, product name RP207” was used. The surface protective film has a pressure-sensitive adhesive layer (corresponding to a second pressure-sensitive adhesive layer) having a thickness of 15 μm.

<Formation of adhesive layer with release film>
The pressure-sensitive adhesive solution was applied to the surface of a release film (separator) made of a polyethylene terephthalate film (thickness 38 μm or 50 μm) subjected to a release treatment so that the thickness after drying was 20 μm, and then dried. A layer (corresponding to the first pressure-sensitive adhesive layer) was formed. Next, the pressure-sensitive adhesive layer is bonded to the polarizer side of the single protective polarizing film A having a surface protective film, and the optical film of the present invention (polarizing film with a pressure-sensitive adhesive layer having a release film and a surface protective film). Was made.

<Single transmittance T and polarization degree P of polarizer>
The single transmittance T and the polarization degree P of the obtained polarizing film were measured using a spectral transmittance measuring device with an integrating sphere (Dot-3c of Murakami Color Research Laboratory).
The degree of polarization P is the transmittance when two identical polarizing films are overlapped so that their transmission axes are parallel (parallel transmittance: Tp), and overlapped so that their transmission axes are orthogonal to each other. It is calculated | required by applying the transmittance | permeability (orthogonal transmittance | permeability: Tc) at the time of combining to the following formula | equation. Polarization degree P (%) = {(Tp−Tc) / (Tp + Tc)} ^1/2 × 100
Each transmittance is represented by a Y value obtained by correcting visibility with a two-degree field of view (C light source) of JIS Z8701, with 100% of the completely polarized light obtained through the Granteller prism polarizer.

<Measurement of peel force>
About the polarizing film with an adhesive layer which has the release film and surface protection film which were obtained in the Example and the comparative example, it cut | judged to 25 mm x 100 mm (absorption axis direction is 25 mm) and 100 mm x 25 mm (absorption axis direction is 100 mm). After peeling the film on the side that does not measure the peeling force of the release film and the surface protective film, the film is pasted on a non-alkali glass having a thickness of 0.5 mm with a double-sided tape (manufactured by Nitto Denko Corporation, double-sided tape No. 511). Combined. A cellophane tape is applied to the short side edge of the polarizing film with an adhesive layer bonded to an alkali-free glass, and only the starting part is peeled off in advance, and then the surface protective film is 180 ° peeled at 0.3 m / min using Tensilon. It peeled in parallel with the long side direction of the film at a min speed. In addition, the peeling force was measured at each of 25 mm × 100 mm (absorption axis direction is 25 mm) and 100 mm × 25 mm (absorption axis direction is 100 mm), and the average value was adopted.
The release forces of the release films were all 0.16 N / 25 mm.
The peel strength of the surface protective film was 0.09 N / 25 mm in all cases.

<Peeling roll>
A double-sided pressure-sensitive adhesive tape (Nitto Denko Corporation, No. 511) having a width of 15 mm and a thickness of 130 μm was wound in a spiral shape on a rubber roll having a diameter of 15 mm or 40 mm and a width of 200 mm to prepare an adhesive roll. In the adhesive roll, the interval at which the adhesive tape was not applied was 15 mm.

Examples 1-3 and Comparative Examples 1-3
Peeling was performed in the manner shown in Table 1. About the polarizing film with an adhesive layer which has a mold release film and a surface protection film, it cut | judged to 150x50 mm to make the rectangular object (sample). As the release film and the surface protective film, those shown in Table 1 were used in each Example and Comparative Example, respectively. With the release film side of the sample facing upward, as shown in FIG. 6, the surface protective film side of the sample is placed on a flat table B (glass) with a double-sided tape (manufactured by Nitto Denko Corporation, double-sided tape No. 511). Fixed on top.
Next, as shown in FIG. 5, the case where the adhesive roll was installed so that a portion where the adhesive tape was not attached was placed at one vertex of the sample was regarded as “adaptive”. The case where it was installed so that the place where the adhesive tape was affixed at the apex was regarded as “unsuitable”. Moreover, the adhesive roll was installed so that the advancing direction might move the diagonal of one vertex of the sample. Next, while manually pressing the adhesive roll, the release film is moved in the diagonal direction at the peeling speed shown in Table 1 (fast: 5 m / min, slow: 0.3 m / min) to peel the release film. did. The peeling was performed 5 times.
A: Only the release film was peeled off 5 times.
(Triangle | delta): Only the release film peeled 4 times. The surface protective film was peeled once.
X: It peeled in the interface of a surface protective film and a polarizing film all 5 times.

  In the examples, the release film was able to be peeled regardless of the constitution, the peeling speed, and the roll diameter of the polarizing film with the pressure-sensitive adhesive layer having the release film and the surface protective film.

F Optical film in a rectangular state 1, 1 'Polarizing film 1a Polarizer 1b Protective film 2 First adhesive layer 3 Release film 4, 4' Surface protective film 41 Base film 42 Second adhesive layer

R Adhesive roll a Adhesive member b Except adhesive member r Roll B Flatbed

Claims (9)

From the rectangular optical film in which the release film, the first pressure-sensitive adhesive layer, the polarizing film, and the surface protective film are laminated in this order, the release film is pressed while pressing the adhesive member to the release film side of the optical film. A method of peeling,
The polarizing film has a thickness of 60 μm or less,
The peeling method characterized by performing the said press so that the vertex of the said optical film may not be included in the initial press part which presses the said release film initially with the said adhesive member.   The peeling method according to claim 1, wherein a peeling force (1) of the release film is larger than a peeling force (2) of the surface protective film.   The peeling method according to claim 1, wherein the adhesive member is an adhesive roll having the adhesive member on a part of a roll surface.   The peeling method according to claim 3, wherein the adhesive member of the adhesive roll is provided in a spiral shape on the roll surface.   The initial pressing portion of the adhesive member is in the vicinity of an apex portion that does not include the apex portion of the optical film, and a direction in which the release film is peeled is a diagonal direction of the optical film. The peeling method in any one of -4.   The peeling method according to claim 1, wherein the polarizing film has a polarizer having a thickness of 10 μm or less.   The peeling method according to claim 1, wherein the polarizing film is a single protective polarizing film having a protective film only on one side of a polarizer. A release film, a first pressure-sensitive adhesive layer, a polarizing film and a surface protective film are rectangular optical films laminated in this order,
Preparing the polarizing film having a thickness of 60 μm or less (1),
The step (2) of peeling the release film from the optical film by the peeling method according to any one of claims 1 to 7, and
The manufacturing method of an optical display panel which has the process (3) which affixes the 1st adhesive layer side of the said optical film from which the said release film peeled on the one surface of an optical cell. 9. The method of manufacturing an optical display panel according to claim 8, wherein the optical cell is a liquid crystal cell or an organic EL cell.

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