JP2017142293A - Optical film and optical display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet-like optical film with which an optical display panel can be manufactured while suppressing a reduction in handling ability in a sheet-to-panel system.SOLUTION: There is provided an optical film 10 having a release film 15, an adhesive layer 11, a polarization film 12, and a surface protective film 14 laminated in this order, where the polarization film 12 has a thickness of 60 μm or less, and the surface protective film 14 has a thickness satisfying the relational expression 0.8≤(thickness of surface protective film)/(thickness of polarization film).SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical film and an optical display panel.

  There is a method (hereinafter also referred to as “sheet-to-panel method”) in which a polarizing film in a single wafer state is attached to an optical cell (see, for example, Patent Document 1).

JP 2006-039238 A JP 2009-062108 A

  In recent years, as an optical display panel is made thinner, a polarizing film thinner than the conventional one (for example, a thickness of 60 μm or less) is being developed. As described above, the polarizing film thinner than the conventional one has a low waist (elastic modulus) and is likely to be twisted or curled. Therefore, when the polarizing film is thin, although technical improvements have progressed over the years, in the sheet-to-panel system, the polarizing film is transported, the release film is peeled off, and the polarizing film piece is a liquid crystal cell. There is a concern that handling such as bonding to the surface is difficult and the yield decreases.

  The present invention has been made in view of the above circumstances, and provides a sheet-like optical film capable of suitably producing an optical display panel using a thin polarizing film even by a sheet-to-panel method. With the goal.

The present invention is an optical film having a configuration in which a release film, an adhesive layer, a polarizing film, and a surface protective film are laminated in this order,
The polarizing film has a thickness of 60 μm or less,
The surface protective film satisfies a relational expression of 0.8 ≦ (surface protective film thickness) / (polarizing film thickness).

  According to this configuration, although the polarizing film is thin, the surface protective film is thickened (specifically, 0.8 ≦ (surface protective film thickness) / (polarizing film thickness)). The waist (elastic modulus) is strengthened, and the handling property of the polarizing film in the sheet-to-panel system can be enhanced. Therefore, it is possible to suitably manufacture an optical display panel in which a thin polarizing film is bonded using a sheet-to-panel method.

  As one embodiment of the above invention, the thickness of the surface protective film satisfies (thickness of surface protective film) / (thickness of polarizing film) ≦ 3.0. The surface protective film needs to be peeled off from the optical display panel in the next assembly step. The thicker the surface protective film, the more the surface protective film is peeled off from the optical display panel. The “trigger peeling”, which is the operation to start peeling with grabbing, becomes heavy. As a result, when the surface protective film is peeled from the optical display panel, delamination of the optical film (for example, peeling between the polarizer and the polarizer protective film, peeling between the pressure-sensitive adhesive layer and the polarizing film, adhesion) There is an increased risk of peeling between the agent layer and the optical cell. Therefore, by controlling the thickness of the surface protective film so as to satisfy (surface protective film thickness) / (polarizing film thickness) ≦ 3.0, the surface peelability of the surface protective film is improved and the interlayer of the optical film is improved. Peeling can be suppressed.

  As one embodiment of the invention, the surface protective film is laminated on a polarizing film via a second pressure-sensitive adhesive layer. In another embodiment, the protective film is a self-adhesive film.

  As one embodiment of the invention, the polarizing film includes a polarizer having a thickness of 10 μm or less. Such a polarizing film containing a polarizer having a thickness of 10 μm or less has a significantly low waist (elastic modulus). As a result, in the sheet-to-panel system, there is a high possibility that twisting or curling will occur. Therefore, the present invention is particularly suitable for the polarizing film.

  As one embodiment of the invention, the release film is peeled off and used to manufacture an optical display panel having a configuration in which an adhesive layer, a polarizing film, and a surface protective film are laminated in this order on one surface of an optical cell. It is done.

Another invention is an optical display panel having a configuration in which an adhesive layer, a polarizing film, and a surface protective film are laminated in this order on one surface of an optical cell,
The polarizing film has a thickness of 60 μm or less,
The surface protective film is an optical display panel having a thickness satisfying 0.8 ≦ (thickness of surface protective film) / (thickness of polarizing film).

  As one embodiment of the above invention, the thickness of the surface protective film satisfies (thickness of surface protective film) / (thickness of polarizing film) ≦ 3.0.

  As one embodiment of the invention, the optical cell is a liquid crystal cell or an organic EL cell.

Cross-sectional schematic diagram of an optical film in a single wafer state Cross-sectional schematic diagram of an optical film in a single wafer state according to another embodiment Perspective schematic view of a single wafer optical film affixed to an optical cell

  The optical film 10 of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic cross-sectional view of the optical film 10. The optical film 10 has a configuration in which a release film 15, a first pressure-sensitive adhesive layer 11, a polarizing film 12, a second pressure-sensitive adhesive layer 13, and a surface protective film 14 are laminated in this order.

  In another embodiment shown in FIG. 2, the surface protective film 14 is made of a self-adhesive film and is laminated on the polarizing film 12 without an adhesive layer.

<Polarizing film>
In the present invention, a polarizing film having a thickness of 60 μm or less is used. The thickness of the polarizing film is preferably 55 μm or less, and more preferably 50 μm or less from the viewpoint of thinning. As a polarizing film, for example, (1) a configuration in which protective films are laminated on both sides of a polarizer in this order (both protective polarizing films), and (2) a configuration in which a protective film is laminated only on one side of a polarizer ( 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, a polarizing film including a polarizer having a thickness of 10 μm or less has a significantly low waist (elastic modulus), and therefore, there is a high possibility of twisting and curling in the sheet-to-panel system. Therefore, 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 preferably configured to satisfy the condition of P ≧ 99.9 (however, T ≧ 42.3). 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 a 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.

  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 release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent 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 transparent 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 is preferably 5 to 50 μm or less, more preferably 5 to 45 μm, from the viewpoints of workability such as strength and handleability and thin layer properties.

  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. The functional layers such as the hard coat layer, antireflection layer, antisticking layer, diffusion layer and antiglare layer can be provided on the transparent protective film itself, and separately provided separately from the transparent protective film. You can also.

(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.

  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.

  In addition, in lamination | stacking of a polarizer and a protective film, an easily bonding layer can be provided between a transparent 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.

<Surface protection film>
In the optical film, the surface protective film is provided on one surface of the polarizing film (the surface on which the pressure-sensitive adhesive layer is not laminated) to protect the polarizing film. The thickness of the surface protective film satisfies 0.8 ≦ (thickness of the surface protective film) / (thickness of the polarizing film), thereby improving the handling properties of the optical film in the sheet-to-panel system. The surface protective film preferably satisfies 1.0 ≦ (thickness of the surface protective film) / (thickness of the polarizing film) from the viewpoint of further strengthening the waist (elastic modulus) of the entire optical film.
On the other hand, the thicker the surface protective film, the heavier the “cracking peel” when peeling the surface protective film from the optical display panel (the peelability becomes worse), and the delamination of the optical film may occur. The surface protective film preferably satisfies (thickness of protective film / thickness of polarizing film) ≦ 3.0, and more preferably satisfies (thickness of protective film / thickness of polarizing film) ≦ 2.5.

The surface protective film is laminated on the polarizing film through the pressure-sensitive adhesive layer, or is composed of a self-adhesive film and is laminated on the polarizing film without going through the pressure-sensitive adhesive layer, but protects the polarizing film. From a viewpoint, it is preferable to be laminated on the polarizing film via the pressure-sensitive adhesive layer (FIG. 1). As 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 surface protective 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 surface protective film is not particularly limited as long as 0.8 ≦ (thickness of the surface protective film) / (thickness of the polarizing film), but is preferably 35 μm to 100 μm or less, and more than 38 μm. Is preferably 100 μm or less.

  As the pressure-sensitive adhesive used for laminating the surface protective film, a pressure-sensitive adhesive having a base polymer of (meth) acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately used. Can be 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 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.

  The surface protective film can be provided with a release treatment layer on the surface opposite to the surface on which the pressure-sensitive adhesive layer is provided, using a low adhesive material such as silicone treatment, long-chain alkyl treatment, or fluorine treatment.

<Adhesive layer>
An appropriate pressure-sensitive adhesive can be used for forming the 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 of forming the pressure-sensitive adhesive layer, for example, a release film obtained by peeling the pressure-sensitive adhesive (applied to a separator or the like, and after removing the polymerization solvent and the like to form a pressure-sensitive adhesive layer, FIG. 2 (A) In the embodiment of FIG. 2, the method of transferring to a polarizer (or transparent protective film in the embodiment of FIG. 2B), or in the embodiment of FIG. 2A to the polarizer (or the transparent protective film in the embodiment of FIG. 2B). The pressure-sensitive adhesive is applied, and the polymerization solvent is dried and removed to form a pressure-sensitive adhesive layer on the polarizer, etc. In addition, in applying the pressure-sensitive adhesive, one or more types other than the polymerization solvent are appropriately used. A new solvent may be added.

  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 2
It is 0 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 pressure-sensitive adhesive layer until it is put to practical use. 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 thickness of the release film is usually 5 to 200 μm, preferably 5 to 100 μm, and more preferably 5 to 50 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film.

  The optical display panel of the present invention will be described below with reference to FIG. FIG. 3 is a schematic perspective view of the optical film 10 in a single wafer state attached to the optical cell C. FIG. A single wafer optical film 10 is provided on one main surface of the optical cell C. When the first side length of the main surface size of the optical cell C is x1, and the second side length y1 in the direction orthogonal to the first side, the first side length of the sheet-like optical film 10 is x2, When the second side length orthogonal to one side is y2, the relationship is x1> x2 and y1> y2. This relationship corresponds to the optical film corresponding to the main surface size of the optical cell of the present invention, but is not limited to this, and may be a relationship of x1 = x2 and y1 = y2. In FIG. 3, x1> y1, but this is not limited, and x1 = y2 or x1 <y1 may be satisfied.

  Even if the thickness of the polarizing film 12 is small, the surface protective film 14 is increased in thickness, so that the sheet-to-panel optical film 10 of the present embodiment is suitably opticalized in the sheet-to-panel system without impairing handling properties. It can be attached to the cell C.

  That is, in order to manufacture an optical display panel in which the first pressure-sensitive adhesive layer 11, the polarizing film 12, the second pressure-sensitive adhesive layer 13, and the surface protective film 14 are laminated in this order on one surface or both surfaces of the optical cell C. The single wafer optical film 10 of the embodiment can be suitably used. The optical film 10 from which the release film 15 has been peeled off is bonded to the optical cell C by a sheet-to-panel type bonding apparatus.

<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.

(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. The organic EL display panel has a polarizing film bonded to one or both sides of an organic EL cell, 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.

<Polarizing film>
(Preparation of polarizer A0)
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.

(Preparation of 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.

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

(Preparation of polarizing film A)
After laminating the protective film on one surface of the polarizer A0 of the optical film laminate, applying the UV curable adhesive so that the thickness of the adhesive layer after curing is 0.5 μm. The adhesive was cured by irradiating ultraviolet rays as active energy rays. For ultraviolet irradiation, a gallium-filled metal halide lamp, irradiation device: Fusion UV Systems, Inc. Light HAMMER 10, Inc., bulb: V bulb, peak illuminance: 1600 mW / cm 2, integrated irradiation amount 1000 / mJ / cm 2 (wavelength 380 to 440 nm) Used, 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 polarizing film A using a thin polarizer. The optical properties of the obtained polarizing film A were a single transmittance of 42.8% and a degree of polarization of 99.99%. The thickness of the polarizing film A is 45.5 μm.

(Preparation of polarizing film B)
In the same manner as in the polarizing film A, the transparent protective film was bonded to both surfaces of the polarizer A0 through the ultraviolet curable adhesive. The optical properties of the obtained piece-protecting polarizing film B were a transmittance of 42.8% and a degree of polarization of 99.99%. The thickness of the polarizing film B is 86 μm.

<Formation of adhesive layer>
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. The pressure-sensitive adhesive solution was applied to the surface of a release film (separator) made of a peeled polyethylene terephthalate film (thickness 38 μm) so that the thickness after drying was 25 μm, dried, and then the pressure-sensitive adhesive layer ( Corresponding to the first pressure-sensitive adhesive layer).

<Production of pressure-sensitive adhesive layer-attached polarizing film A1>
Subsequently, the adhesive layer formed in the peeling process surface of the said release film (separator) was bonded together to the polarizer side of the polarizing film A, and the polarizing film with an adhesive layer was produced. The thickness of the pressure-sensitive adhesive layer-attached polarizing film A1 is 45.5 + 25 + 38 = 108.5 μm.

<Lamination of surface protective film>
As the surface protective film, a polyester resin film “product name RP301” manufactured by Nitto Denko Corporation was used. Substrates different in thickness from 25 μm, 38 μm, 50 μm, 75 μm, 100 μm, and 150 μm were prepared. The thickness of the pressure-sensitive adhesive layer (corresponding to the second pressure-sensitive adhesive layer) is all 21 μm.

Example 1
The single-wafer optical film of Example 1 has a configuration in which a surface protective film having a thickness of 38 μm is laminated on the polarizing film A1 with the pressure-sensitive adhesive layer.
(Thickness of surface protective film) / (Thickness of polarizing film) = 38 / 45.5 = 0.84 (rounded off to the third decimal place, and so on)
Trigger peeling force = 0.3 [N / 15mm]
The trigger peel force conforms to the following measurement. That is, the obtained single-wafer optical film is cut into 15 mm × 100 mm (absorption axis direction is 50 mm) and 100 mm × 15 mm (absorption axis direction is 100 mm) and bonded to non-alkali glass having a thickness of 0.5 mm each. It was. Cellophane tape was attached to the short side edge of the optical film bonded to the alkali-free glass, and the surface protective film was peeled off at 180 ° peel and 0.3 m / min using Tensilon. The peak value of the peeling force at that time was defined as “triggering peeling force”. In addition, each peeling force of 15 mm x 100 mm (absorption axis direction is 50 mm) and 100 mm x 15 mm (absorption axis direction is 100 mm) was measured, and the average value was adopted. The trigger peel force is measured at room temperature.

(Example 2)
The single-wafer optical film of Example 2 has a configuration in which a surface protective film having a thickness of 50 μm is laminated on the polarizing film A1 with the pressure-sensitive adhesive layer.
(Thickness of surface protective film) / (Thickness of polarizing film) = 50 / 45.5 = 1.10
Trigger peeling force = 0.7 [N / 15mm]

(Example 3)
The single-wafer optical film of Example 3 has a configuration in which a surface protective film having a thickness of 75 μm is laminated on the polarizing film with adhesive layer A1.
(Thickness of surface protective film) / (Thickness of polarizing film) = 75 / 45.5 = 1.65
Trigger peel force = 1.5 [N / 15mm]

Example 4
The optical film in a single wafer state of Example 4 has a configuration in which a surface protective film having a thickness of 100 μm is laminated on the polarizing film A1 with the pressure-sensitive adhesive layer.
(Thickness of surface protective film) / (Thickness of polarizing film) = 100 / 45.5 = 2.20
Trigger peel force = 2.5 [N / 15mm]

(Example 5)
The single-wafer optical film of Example 5 has a configuration in which a surface protective film having a thickness of 150 μm is laminated on the polarizing film A1 with the pressure-sensitive adhesive layer.
(Thickness of surface protective film) / (Thickness of polarizing film) = 150 / 45.5 = 3.30
Trigger peel force = 5.0 [N / 15mm]

(Comparative Example 1)
The single-wafer optical film of Comparative Example 1 has a configuration in which a surface protective film having a thickness of 25 μm is laminated on the polarizing film A1 with the pressure-sensitive adhesive layer.
(Thickness of surface protective film) / (Thickness of polarizing film) = 25 / 45.5 = 0.55
Trigger peeling force = 0.2 [N / 15mm]

<Preparation of polarizing film B1 with an adhesive layer>
Subsequently, the adhesive layer formed in the peeling process surface of the said release film (separator) was bonded together to the polarizer side of the polarizing film B, and the polarizing film with an adhesive layer was produced. The thickness of the polarizing film with adhesive layer B1 is 86 + 25 + 38 = 149 μm.

(Reference Example 1)
The single-wafer optical film of Reference Example 1 has a configuration in which a surface protective film having a thickness of 38 μm is laminated on the polarizing film B1 with an adhesive layer.
(Thickness of surface protective film) / (Thickness of polarizing film) = 38/86 = 0.44
Trigger peeling force = 0.3 [N / 15mm]

(Reference Example 2)
The single-wafer optical film of Reference Example 2 has a configuration in which a surface protective film having a thickness of 200 μm is laminated on the polarizing film with adhesive layer B1.
(Thickness of surface protective film) / (Thickness of polarizing film) = 200/86 = 2.33
Trigger peel force = 5.0 [N / 15mm]

  Using a sheet-to-panel apparatus, the release films were peeled off from the single-layer optical films of Examples 1 to 5, Comparative Example 1, Reference Examples 1 and 2, and then the glass plate (optical (N = 100 times). As a result, the optical films in the single wafer state of Examples 1 to 5 had no problem in handling properties and could be suitably bonded to the optical cell. However, in Example 5, when the surface protective film was peeled off from the optical film bonded to the glass plate, the peeling was heavy and the interlayer peeling of the polarizing film occurred. Moreover, in Reference Examples 1 and 2, since the polarizing film was thick, it was thickened as a whole. On the other hand, the optical films in the single wafer state of Comparative Examples 1 and 2 had a problem in handling properties, and could not be bonded to the optical cell with high accuracy. As a result of the inspection, the defective product determination was 30%.

DESCRIPTION OF SYMBOLS 10 Single wafer optical film 11 1st adhesive layer 12 Polarizing film 13 2nd adhesive layer 14 Surface protection film 15 Release film C Optical cell

Claims (9)

A release film, a pressure-sensitive adhesive layer, a polarizing film, and a surface protective film are optical films having a configuration in which they are laminated in this order,
The polarizing film has a thickness of 60 μm or less,
The surface protective film is an optical film having a thickness satisfying a relational expression of 0.8 ≦ (thickness of the surface protective film) / (thickness of the polarizing film).   The optical film according to claim 1, wherein the surface protective film satisfies a relational expression of (thickness of surface protective film) / (thickness of polarizing film) ≦ 3.0.   The sheet-like optical film of Claim 1 or 2 with which the said surface protection film is laminated | stacked on the polarizing film through the 2nd adhesive layer.   The sheet-like optical film according to claim 1 or 2, wherein the surface protective film is a self-adhesive film.   The optical film according to claim 1, wherein the polarizing film includes a polarizer having a thickness of 10 μm or less.   The said release film is peeled and it is used for manufacturing the optical display panel of the structure by which the adhesive layer, the polarizing film, and the surface protection film are laminated | stacked in this order on the one side of the optical cell. The optical film of any one of these. An optical display panel having a configuration in which an adhesive layer, a polarizing film, and a surface protective film are laminated in this order on one surface of an optical cell,
The polarizing film has a thickness of 60 μm or less,
The surface protective film is an optical display panel having a thickness satisfying a relational expression of 0.8 ≦ (thickness of the surface protective film) / (thickness of the polarizing film).   The optical display panel according to claim 7, wherein the surface protection film satisfies a relational expression of (thickness of surface protection film) / (thickness of polarizing film) ≦ 3.0. The optical cell is a liquid crystal cell or an organic EL cell.
The optical display panel according to claim 7 or 8.

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