JP2019133049A - Optical laminate with surface protective film - Google Patents

Abstract

To provide an optical laminate with a surface protective film, having excellent fast peeling property of the surface protective film and having a superior appearance with significantly suppressed air bubbles.SOLUTION: The optical laminate with a surface protective film of the present invention has an optical laminate and a surface protective film. The surface protective film has a base material and an adhesive layer, and is removably stuck to the optical laminate with the adhesive layer. The adhesive layer of the surface protective film has a thickness of 2 μm or less and has a surface roughness Saof 30 nm or less. The optical laminate has a surface roughness Saof 30 nm or less on the surface in contact with the adhesive layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical laminate with a surface protective film.

  Until the image display device to which the optical laminate is applied is actually used for the optical laminate (for example, a polarizing plate or a laminate including a polarizing plate), the optical laminate (finally, In order to protect the image display device, a surface protective film is detachably bonded. Practically, the optical laminate / surface protective film laminate is bonded to the display cell to produce an image display device, and the surface protective film is peeled off at an appropriate time thereafter. The surface protective film typically has a resin film as a base material and an adhesive layer. In recent years, depending on the purpose, it may be required to lightly peel and / or thin the pressure-sensitive adhesive layer of the surface protective film. When a surface protective film having a thin pressure-sensitive adhesive layer is bonded to the optical laminate, bubbles may be generated on the entire bonded surface. In this case, even if there is no problem in the display cell itself to which the optical laminate is bonded, the image display device may be determined to be defective in the inspection before shipment due to bubbles from the surface protective film. is there. As a result, there is a problem in that the efficiency from manufacture to shipment of the image display device is reduced, and an improvement or solution is strongly desired. Furthermore, continuous improvement is requested | required about the peelability from an optical laminated body as a basic characteristic of a surface protection film.

JP 2006-088651 A

  The present invention has been made in order to solve the above-described conventional problems, and its main purpose is to provide a surface protective film with excellent high-speed peelability of the surface protective film and excellent appearance by suppressing air bubbles. The object is to provide an optical laminate.

An optical laminate with a surface protective film according to an embodiment of the present invention has an optical laminate and a surface protective film; the surface protective film has a base material and an adhesive layer, and the adhesive layer is interposed through the adhesive layer. The adhesive layer of the surface protective film is releasably bonded; the thickness of the pressure-sensitive adhesive layer of the surface protective film is 2 μm or less, and the surface roughness Sa ₁ of the pressure-sensitive adhesive layer is 30 nm or less; The surface roughness Sa ₂ of the surface in contact with the pressure-sensitive adhesive layer of the body is 30 nm or less.
In one embodiment, the thickness of the said adhesive layer is 1 micrometer or less.
In one embodiment, in one embodiment the surface roughness Sa ₁ of the pressure-sensitive adhesive layer is 10nm or less, the surface roughness Sa ₂ of the surface in contact with the adhesive layer of the optical stack 10nm or less It is.
In one embodiment, the optical laminated body with a surface protective film has a high-speed peeling force of 0.20 N / 25 mm or less.
In one embodiment, the thickness of the surface protection film is 15 μm to 60 μm.
In one embodiment, the said surface protection film further has an antistatic layer on the opposite side to the said adhesive layer of the said base material.
In one embodiment, the base resin of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is selected from a silicone resin, an acrylic resin, a urethane resin, and a rubber resin.
In one embodiment, the optical layered body includes a polarizer. In one embodiment, the thickness of the polarizer is 3 μm to 30 μm.

According to the present invention, the optical laminate with a surface protective film, to optimize the surface roughness Sa ₂ the thickness of the adhesive layer and the surface roughness Sa ₁ as optical stack in contact with the adhesive layer of the surface protective film Thereby, it is excellent in the high-speed peelability of a surface protective film, and the optical laminated body with a surface protective film excellent in the external appearance by which air bubbles are suppressed notably can be implement | achieved.

It is a schematic sectional drawing of the optical laminated body with a surface protection film by one embodiment of this invention.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

A. Outline of Optical Laminate with Surface Protective Film FIG. 1 is a schematic cross-sectional view of an optical laminate with a surface protective film according to one embodiment of the present invention. The optical laminate 100 with a surface protective film of the present embodiment includes an optical laminate 10 and a surface protective film 20. The surface protective film 20 has a base material 21 and an adhesive layer 22. The surface protective film 20 is detachably bonded to the optical laminate 10 via the pressure-sensitive adhesive layer 22. Any appropriate treatment layer (not shown) may be provided on the side of the surface protective film 20 opposite to the pressure-sensitive adhesive layer 22 of the base material 21 as necessary. In the embodiment of the present invention, the thickness of the pressure-sensitive adhesive layer 22 is 2 μm or less, and the surface roughness Sa ₁ is 30 nm or less; the surface roughness Sa of the surface in contact with the pressure-sensitive adhesive layer 22 of the optical laminate 10. ₂ is 30 nm or less. Thus, the thickness of the pressure-sensitive adhesive layer of the surface protective film is set to be very thin, the surface roughness Sa ₁ is set to a predetermined value or less, and the surface roughness Sa ₂ of the surface in contact with the pressure-sensitive adhesive layer of the optical laminated body is set. Is set to a predetermined value or less, it is possible to realize an optical laminate with a surface protective film that is excellent in high-speed peelability of the surface protective film and excellent in appearance (bubbles are remarkably suppressed). Practically, the optical laminate with a surface protective film is bonded to a display cell to produce an image display device, and then the surface protective film is peeled and removed at an appropriate time point. If there are bubbles in the display cell itself, there is no problem with the display cell itself to which the optical laminate with the surface protective film is bonded. There is a case where it is judged as defective in the inspection. As a result, there is a problem in that the efficiency from manufacture to shipment of the image display device is reduced. Since the optical laminate with a surface protective film according to the embodiment of the present invention can solve such problems, the industrial value is very large. Furthermore, since the optical laminate with a surface protective film according to the embodiment of the present invention is excellent in the high-speed peelability of the surface protective film as described above, it is very useful from the viewpoints of handleability and operability.

  The optical laminate with a surface protective film typically has a high-speed peel force of 0.20 N / 25 mm or less. As described above, according to the embodiment of the present invention, such an excellent high-speed peeling force (that is, very small and easy to peel) can be realized. The lower the high speed peeling force, the better. The high speed peeling force is preferably 0.10 N / 25 mm or less, more preferably 0.08 N / 25 mm or less, and still more preferably 0.05 N / 25 mm or less. The lower limit of the high speed peeling force can be, for example, 0.01 N / 25 mm. The high-speed peeling force is a peeling force at a pulling speed of 30 m / min and a peeling angle of 180 °.

  As the optical laminate, a laminate including a layer having any appropriate optical function can be adopted. Specific examples of the optical laminate include a polarizing plate, a retardation plate, a conductive film for a touch panel, a surface treatment film, and a laminate having an appropriate configuration according to the purpose (for example, an antireflection circle). Polarizing plate, polarizing plate with conductive layer for touch panel, polarizing plate with retardation layer, prism sheet integrated polarizing plate).

  Hereinafter, an optical laminate with a surface protective film using a polarizing plate as an example of an optical laminate will be specifically described. However, those skilled in the art can apply the present invention to any appropriate optical laminate as described above. It is self-evident.

B. Polarizing plate The polarizing plate typically has a polarizer and a protective layer disposed on one side or both sides of the polarizer. When the protective layer is disposed only on one side of the polarizer, the protective layer can typically be disposed outside the polarizer (on the side opposite to the display cell). In the embodiment of the present invention, as described above, the surface roughness Sa ₂ of the surface in contact with the pressure-sensitive adhesive layer of the optical laminate (polarizing plate) is 30 nm or less. The surface can be substantially the surface of a protective layer disposed outside the polarizer.

As described above, the surface roughness Sa ₂ is 30 nm or less, preferably 15 nm or less, more preferably 10 nm or less, further preferably 5 nm or less, particularly preferably 3 nm or less, and particularly preferably 1 nm. It is as follows. The lower limit of the surface roughness Sa ₂ can be, for example, 0.1 nm. If the surface roughness Sa ₂ is within such a range, the synergistic effect with the thickness of the pressure-sensitive adhesive layer of the surface protective film and the surface roughness Sa ₁ achieves excellent high-speed peelability of the surface protective film, In addition, excellent appearance can be realized by significantly suppressing bubbles. Note that the surface roughness Sa ₂ can be measured according to ISO 25178-6 (2010) or JIS B 0686-1: 2014 (the same applies to Sa ₁ described later).

B-1. Polarizer Any appropriate polarizer can be adopted as the polarizer of the polarizing plate. For example, the resin film forming the polarizer may be a single-layer resin film or may be formed from a laminate of two or more layers.

  Specific examples of polarizers composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and ethylene / vinyl acetate copolymer partially saponified films. In addition, there may be mentioned polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with dichroic substances such as iodine and dichroic dyes, PVA dehydrated products and polyvinyl chloride dehydrochlorinated products. Preferably, a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching is used because of excellent optical properties.

  The dyeing with iodine is performed, for example, by immersing a PVA film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye | stain after extending | stretching. If necessary, the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment and the like. For example, by immersing the PVA film in water and washing it before dyeing, not only can the surface of the PVA film be cleaned of dirt and anti-blocking agents, but the PVA film can be swollen to cause uneven staining. Can be prevented.

  As a specific example of a polarizer obtained by using a laminate, a laminate of a resin substrate and a PVA resin layer (PVA resin film) laminated on the resin substrate, or a resin substrate and the resin Examples thereof include a polarizer obtained by using a laminate with a PVA resin layer applied and formed on a substrate. For example, a polarizer obtained by using a laminate of a resin base material and a PVA resin layer applied and formed on the resin base material may be obtained by, for example, applying a PVA resin solution to a resin base material and drying it. A PVA-based resin layer is formed thereon to obtain a laminate of a resin base material and a PVA-based resin layer; the laminate is stretched and dyed to make the PVA-based resin layer a polarizer; obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Further, the stretching may further include, if necessary, stretching the laminate in the air at a high temperature (for example, 95 ° C. or higher) before stretching in the boric acid aqueous solution. The obtained resin base material / polarizer laminate may be used as it is (that is, the resin base material may be used as a protective layer of the polarizer), and the resin base material is peeled from the resin base material / polarizer laminate. Any appropriate protective layer according to the purpose may be laminated on the release surface. Details of a method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. This publication is incorporated herein by reference in its entirety.

  The thickness of the polarizer is typically 3 μm to 30 μm. In one embodiment, the thickness of the polarizer is preferably 15 μm or less, more preferably 1 μm to 12 μm, still more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. In another embodiment, the thickness of the polarizer is preferably more than 15 μm and 25 μm or less.

B-2. Protective layer The protective layer is formed of any suitable film that can be used as a protective layer for a polarizer. Examples of the resin film forming material include (meth) acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, and polyethylene terephthalate resins. And ester resins such as polyamide resins, polycarbonate resins, and copolymer resins thereof. A (meth) acrylic resin is preferred. The “(meth) acrylic resin” refers to an acrylic resin and / or a methacrylic resin.

  In one embodiment, a (meth) acrylic resin having a glutarimide structure is used as the (meth) acrylic resin. Examples of (meth) acrylic resins having a glutarimide structure (hereinafter also referred to as glutarimide resins) include, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, and JP-A-2006-328329. 2006-328334, JP-A 2006-337491, JP-A 2006-337492, JP-A 2006-337493, JP-A 2006-337469, JP-A 2007-009182, JP-A 2009- Nos. 161744 and 2010-284840. These descriptions are incorporated herein by reference.

  The protective layer provided on the side to which the surface protective film is bonded is preferably subjected to a surface treatment for reducing the contact angle. A typical example of such surface treatment is corona treatment. The conditions for corona treatment can be appropriately set so that the desired contact angle is obtained for the liquid.

  When the polarizing plate is disposed on the viewing side of the image display device, the protective layer disposed on the viewing side of the polarizing plate is subjected to surface treatment such as hard coating treatment, antireflection treatment, and anti-sticking treatment as necessary. It may be given. Furthermore / or, if necessary, the protective layer may be treated to improve visibility when viewed through polarized sunglasses (typically, an (elliptical) circular polarization function is imparted, an ultrahigh phase difference is provided. May be applied).

  The protective layer (inner protective layer) disposed on the display cell side of the polarizer is preferably optically isotropic. In this specification, “optically isotropic” means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is −10 nm to +10 nm. Say. The inner protective layer can be composed of any suitable material as long as it is optically isotropic. The material can be appropriately selected from the above materials.

  The thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and still more preferably 5 μm to 150 μm. In addition, when the surface treatment is performed, the thickness of the protective layer is a thickness including the thickness of the surface treatment layer.

B-3. Treatment layer Any appropriate treatment layer can be preferably formed on the side of the polarizing plate where the surface protective film is bonded. The treatment layer preferably has a contact angle reduction function. Specific examples of the treatment layer include an antistatic layer, a hydrophilic layer, and a hard coat layer.

  The antistatic layer typically includes a conductive material and a binder resin. Any appropriate conductive material can be used as the conductive material. Preferably, a conductive polymer is used. Examples of the conductive polymer include polythiophene polymer, polyacetylene polymer, polydiacetylene polymer, polyin polymer, polyphenylene polymer, polynaphthalene polymer, polyfluorene polymer, polyanthracene polymer. Polymer, polypyrene polymer, polyazulene polymer, polypyrrole polymer, polyfuran polymer, polyselenophene polymer, polyisothianaphthene polymer, polyoxadiazole polymer, polyaniline polymer, Examples include polythiazyl polymers, polyphenylene vinylene polymers, polythienylene vinylene polymers, polyacene polymers, polyphenanthrene polymers, polyperinaphthalene polymers, and the like. These may be used alone or in combination of two or more. As the binder resin, a polyurethane resin is preferably used. By using a polyurethane-based resin, an antistatic layer having both flexibility and excellent adhesion to a polarizing plate (substantially a protective layer) can be provided.

  Since a well-known structure in the industry can be adopted for the hydrophilic layer and the hard coat layer, detailed description thereof is omitted.

C. Surface protective film C-1. Base material The base material 21 of the surface protection film 20 may be comprised by arbitrary appropriate resin films. Examples of resin film forming materials include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Is mentioned. Preference is given to ester resins (especially polyethylene terephthalate resins). Such a material has an advantage that the elastic modulus is sufficiently high and deformation is hardly caused even when tension is applied during conveyance and / or bonding.

  The thickness of the substrate is typically 10 μm to 100 μm, preferably 20 μm to 50 μm. With such a thickness, there is an advantage that deformation hardly occurs even when tension is applied during conveyance and / or bonding. In the embodiment of the present invention, since the thickness of the pressure-sensitive adhesive layer is very thin, the thickness of the base material is dominant with respect to the thickness of the surface protective film. In one embodiment, the thickness of the surface protection film can be, for example, 15 μm to 60 μm.

  The elastic modulus of the substrate is typically measured according to JIS K 7127: 1999. The elastic modulus of the substrate is preferably 100 MPa to 350 MPa at a tensile speed of 100 mm / min. If the elastic modulus of the substrate is in such a range, there is an advantage that deformation is hardly caused even when tension is applied during transportation and / or bonding.

C-2. Pressure-sensitive adhesive layer The thickness of the pressure-sensitive adhesive layer is 2 μm or less as described above, preferably 1 μm or less, and more preferably 0.5 μm or less. The thickness of the adhesive layer by setting such an extremely thin, the synergistic effect of the surface roughness Sa ₂ surface roughness Sa ₁ and the optical laminate of the pressure-sensitive adhesive layer excellent in surface protective film High-speed peelability can be achieved, and excellent appearance can be achieved by significantly suppressing bubbles. The lower limit of the thickness is, for example, 0.1 μm. When the thickness is lower than the lower limit, for example, there may be a problem that the end portion is liable to be lifted by processing after bonding to the adherend (optical laminate) or impact of transportation.

As described above, the surface roughness Sa ₁ of the pressure-sensitive adhesive layer is 30 nm or less, preferably 15 nm or less, more preferably 10 nm or less, and further preferably 5 nm or less. The lower limit of the surface roughness Sa ₁ can be, for example, 0.1 nm. If the surface roughness Sa ₁ is in such a range, the synergistic effect with the thickness of the pressure-sensitive adhesive layer and the surface roughness Sa ₂ of the optical laminate achieves excellent high-speed peelability of the surface protective film, In addition, excellent appearance can be realized by significantly suppressing bubbles. Such surface roughness can be realized, for example, by adjusting the surface roughness of the base material and the thickness of the pressure-sensitive adhesive layer in combination.

The storage elastic modulus of the pressure-sensitive adhesive layer is preferably 1.0 × 10 ⁴ Pa to 1.0 × 10 ⁷ Pa, more preferably 2.0 × 10 ⁴ Pa to 5.0 × 10 ⁶ Pa. If the storage elastic modulus of the pressure-sensitive adhesive layer is within such a range, bubbles can be more significantly suppressed. The storage elastic modulus can be determined, for example, from dynamic viscoelasticity measurement at a temperature of 23 ° C. and an angular velocity of 0.1 rad / s.

  Arbitrary appropriate adhesives can be employ | adopted as an adhesive which forms an adhesive layer. Examples of the base resin for the pressure-sensitive adhesive include acrylic resins, styrene resins, silicone resins, urethane resins, and rubber resins. Such a base resin is described in, for example, Japanese Unexamined Patent Application Publication No. 2015-120337 or Japanese Unexamined Patent Application Publication No. 2011-201983. The descriptions in these publications are incorporated herein by reference. Acrylic resins are preferred from the viewpoints of chemical resistance, adhesion for preventing the treatment liquid from entering during immersion, flexibility in the adherend, and the like. Examples of the crosslinking agent that can be included in the pressure-sensitive adhesive include isocyanate compounds, epoxy compounds, and aziridine compounds. The pressure-sensitive adhesive may contain, for example, a silane coupling agent. The formulation of the pressure-sensitive adhesive can be appropriately set according to the purpose.

C-3. Treatment layer As described above, any appropriate treatment layer may be provided on the side of the substrate opposite to the pressure-sensitive adhesive layer as necessary. Specific examples of the treatment layer include an antistatic layer, a hydrophilic layer, and a hard coat layer. The antistatic layer is as described in the above section B-3.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The measuring method of each characteristic in an Example is as follows. Unless otherwise specified, “parts” and “%” in the examples are based on weight.

(1) Thickness The thickness of the pressure-sensitive adhesive layer was measured as follows: a cross section of the film on which the pressure-sensitive adhesive layer was formed was cut out, the cross section was observed with a scanning electron microscope (SEM), and the thickness of the layer was measured. Was measured.
The thickness of the antistatic layer was measured as follows: The surface of the antistatic layer was dyed with RuO ₄ and embedded in an epoxy resin. Thereafter, the section prepared by ultramicrotomy stained with RuO _4, a coating layer cross-section was measured by using a TEM (Hitachi High Technologies Corporation H-7650, accelerating voltage 100 V).
(2) Surface roughness Sa ₁ and Sa ₂
It measured according to JIS B 0681-6: 2014. Using a three-dimensional non-contact surface roughness meter (manufactured by Zygo, product name: NewView 7300) as a measuring instrument, the arithmetic average roughness was measured under the conditions of an objective lens 50 times and a measurement area of 0.14 mm × 0.11 mm. .
(3) High speed peeling force About the optical laminated body (polarizing plate) with a surface protective film obtained by the Example and the comparative example, the peeling force at the time of peeling a surface protective film from a polarizing plate was measured. Peeling was performed at a peel angle of 180 ° and a pulling speed of 30 m / min using a universal tensile tester (manufactured by Minebea Co., Ltd., product name: TCM-1kNB) in an atmosphere of a temperature of 23 ° C. and a humidity of 50% RH.
(4) Appearance About the polarizing plate with a surface protective film obtained in the examples and comparative examples, the generation state of bubbles over the entire surface was visually observed and evaluated according to the following criteria.
○: No bubbles were observed Δ: Bubbles with a major axis of 10 mm or less were observed ×: Bubbles with a major axis of 10 mm or more were observed

<Reference Example 1-1> Polarizing plate 1-1-1. Preparation of Methacrylic Resin Film MS resin (MS-200; copolymer of methyl methacrylate / styrene (molar ratio) = 80/20, manufactured by Nippon Steel Chemical Co., Ltd.) is imidized with monomethylamine (imidation ratio: 5%). The obtained imidized MS resin is a glutarimide unit represented by the general formula (1) (wherein R ¹ and R ³ are methyl groups, R ² is a hydrogen atom), and the general formula (2) in represented by (meth) acrylic acid ester units ^{(R 4} is a hydrogen atom, ^{R 5} is a methyl group), and having a styrene unit, and the acid value was 0.5 mmol / g. For the imidization, a mesh type co-rotating twin screw extruder having a diameter of 15 mm was used. The set temperature of each temperature control zone of the extruder was 230 ° C., the screw rotation speed was 150 rpm, MS resin was supplied at 2.0 kg / hr, and the supply amount of monomethylamine was 2 parts by weight with respect to 100 parts by weight of MS resin. . MS resin was introduced from the hopper, and the resin was melted and filled with a kneading block, and then monomethylamine was injected from the nozzle. A seal ring was placed at the end of the reaction zone to fill the resin. By-products after the reaction and excess methylamine were devolatilized by reducing the pressure at the vent port to -0.08 MPa. The resin that came out as a strand from a die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer. The imidized MS resin was melt-extruded. At this time, 0.66 parts by weight of an ultraviolet absorber (manufactured by ADEKA, “T-712”) was supplied to 100 parts by weight of MS resin. Next, a transparent protective film (thickness 40 μm, Re = 2 nm, Rth = 2 nm) biaxially stretched twice in length and twice in width was produced.

1-1-2. Production of Polarizing Plate As a resin substrate, an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption of 0.75% and a Tg of 75 ° C. was used. One side of the substrate was subjected to corona treatment, and polyvinyl alcohol (degree of polymerization 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization 1200, degree of acetoacetyl modification 4.6) were applied to this corona-treated surface. %, A saponification degree of 99.0 mol% or more, an aqueous solution containing 9: 1 ratio of Nippon Gosei Kagaku Kogyo Co., Ltd., trade name “Gosefimer Z200”) was applied and dried at 25 ° C. to a thickness of 11 μm A PVA resin layer was formed to prepare 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).
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 1.5 parts 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 the rolls having different peripheral speeds in the longitudinal direction (longitudinal direction) so that the total stretching ratio was 5.5 times (in-water stretching).
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).
Subsequently, the above-mentioned methacrylic resin that forms a protective layer by applying an ultraviolet curable adhesive to the surface of the PVA-based resin layer (polarizer) of the laminate so that the adhesive layer thickness after curing is 1.0 μm. A film (thickness: 40 μm) was bonded, heated from the methacrylic resin film side to 50 ° C. using an IR heater, and irradiated with ultraviolet rays to cure the adhesive. Thus, the polarizing plate 1-1 which has the structure of a resin base material (protective layer) / polarizer / protective layer was obtained. The polarizer had a thickness of 5 μm and a single transmittance of 42.3%. The surface roughness Sa ₂ protective layer on the side to be bonded to the surface protective film (methacrylic resin film) was 0.9 nm.

<Reference Example 1-2> Polarizing plate In “Preparation of methacrylic resin film” in Reference Example 1-1-1, when adding an ultraviolet absorber, a core-shell type elastic body was added as a cross-linked elastic body, and the surface roughness was increased. A methacrylic resin film having a thickness Sa ₂ of 4.9 nm was produced. A polarizing plate 1-2 was produced in the same manner as in Example 1 except that this film was used as a protective layer on the side to be bonded to the surface protective film. The method for producing the core-shell type elastic body was as follows.

(Core shell type elastic body)
A mixture of the following composition was charged into a glass reactor, heated to 80 ° C. while stirring in a nitrogen stream, and then a monomer mixture consisting of 25 parts of methyl methacrylate and 1 part of allyl methacrylate and t-butyl hydroper. 25% of the mixed solution with 0.1 part of oxide was charged all at once and polymerized for 45 minutes.
220 parts deionized water
Boric acid 0.3 parts
Sodium carbonate 0.03 parts
N-lauroyl sarcosinate sodium 0.09 parts
Sodium formaldehyde sulfoxylate 0.09 parts
Ethylenediaminetetraacetic acid-2-sodium 0.006 parts
Ferrous sulfate 0.002 parts Subsequently, the remaining 75% of the mixture was continuously added over 1 hour. After completion of the addition, the polymerization was completed by maintaining at the same temperature for 2 hours. During this period, 0.2 part of sodium N-lauroyl sarcosinate was added. The polymerization conversion rate (polymerization amount / monomer charge amount) of the obtained innermost layer crosslinked methacrylic polymer latex was 98%.
The innermost layer polymer latex thus obtained was kept at 80 ° C. in a nitrogen stream, and after adding 0.1 part of potassium persulfate, a single unit consisting of 41 parts of n-butyl acrylate, 9 parts of styrene, and 1 part of allyl methacrylate. The monomer mixture was added continuously over 5 hours. During this time, 0.1 part of potassium oleate was added in three portions. After completing the addition of the monomer mixture, 0.05 part of potassium persulfate was further added and held for 2 hours to complete the polymerization, and rubber particles were obtained. The resulting rubber particles had a polymerization conversion rate of 99% and a particle size of 225 nm. The obtained rubber particle latex was kept at 80 ° C., 0.02 part of potassium persulfate was added, and then a monomer mixture of 14 parts of methyl methacrylate and 1 part of n-butyl acrylate was continuously added over 1 hour. After completion of the addition of the monomer mixture, the mixture was held for 1 hour to obtain a graft copolymer latex. The polymerization conversion rate was 99%. The obtained graft copolymer latex was kept at 80 ° C., and a monomer mixture of 5 parts of methyl methacrylate and 5 parts of n-butyl acrylate was continuously added over 0.5 hours. After completion of the addition of the monomer mixture, the mixture was held for 1 hour to obtain a rubber-containing graft copolymer latex. The polymerization conversion rate was 99%. The obtained rubber-containing graft copolymer latex was subjected to salting out coagulation, heat treatment, and drying with calcium chloride to obtain a white powdery crosslinked elastic body.

<Reference Example 1-3> Polarizing plate A polarizing plate 1-3 was produced in the same manner as Reference Example 1-1 except that an antiglare layer was formed on the surface of the methacrylic resin film. Here, the antiglare layer is the side to be bonded to the surface protective film. Surface roughness Sa ₂ anti-glare layer was 50nm.

<Reference Example 2-1> Surface protective film 2-1-1. Preparation of antistatic layer-forming composition (coating liquid) Prepare an aqueous dispersion containing 25% of a saturated copolymerized polyester resin as a binder (trade name “Vinaroll MD-1480” manufactured by Toyobo Co., Ltd.) (binder dispersion) did. Furthermore, an aqueous dispersion (slip agent dispersion) of carnauba wax (wax ester) as a slip agent was prepared. In addition, an aqueous solution containing 0.5% poly (3,4-dioxythiophene) (PEDOT) as a conductive polymer and 0.8% polystyrene sulfonate (number average molecular weight 150,000) (PSS) (trade name “Baytron” P ”(product of HC Stark) (conductive polymer aqueous solution). In a mixed solvent of water and ethanol, 100 parts of the binder dispersion (solid content), 30 parts of the slip agent dispersion (solid content), 50 parts of the aqueous conductive polymer solution (solid content), a melamine-based crosslinking agent, And stirred well for about 20 minutes to mix thoroughly. In this way, a coating solution for forming an antistatic layer having an NV of about 0.15% was prepared.

2-1-2. Formation of Antistatic Layer A transparent polyethylene terephthalate (PET) film (trade name “Diafoil T600” manufactured by Mitsubishi Chemical Corporation) having a thickness of 50 μm, a width of 30 cm, and a length of 40 cm was prepared. One side of this PET film was subjected to corona treatment. The coating solution was applied to the corona-treated surface of this PET film with a bar coater, and dried by heating at 130 ° C. for 2 minutes. Thus, a laminate of antistatic layer (10 nm) / PET film was produced.

2-1-3. Preparation of adhesive (acrylic polymer)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 100 parts of 2-ethylhexyl acrylate (2EHA), 10 parts of 4-hydroxybutyl acrylate (4HBA), acrylic acid (AA) 0. 02 parts, 0.22 part of 2,2′-azobisisobutyronitrile and 157 parts of ethyl acetate as a polymerization initiator were charged, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was around 65 ° C. Then, a polymerization reaction was carried out for 6 hours to prepare an acrylic polymer (I) solution (40%). The acrylic polymer (I) had a weight average molecular weight of 540,000 and a glass transition temperature (Tg) of −67 ° C.

(Acrylic oligomer)
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, cooler, and dropping funnel, 100 parts of toluene, dicyclopentanyl methacrylate (DCPMA) (trade name: FA-513M, manufactured by Hitachi Chemical Co., Ltd.) ) 60 parts, 40 parts of methyl methacrylate (MMA) and 3.5 parts of methyl thioglycolate as a chain transfer agent. Subsequently, after stirring at 70 ° C. under a nitrogen atmosphere for 1 hour, 0.2 part of 2,2′-azobisisobutyronitrile was added as a polymerization initiator and reacted at 70 ° C. for 2 hours. After making it react at 4 degreeC for 4 hours, it was made to react at 90 degreeC for 1 hour, and the acrylic oligomer solution (51%) was obtained. The acrylic oligomer had a weight average molecular weight of 4000 and a glass transition temperature (Tg) of 144 ° C.

(Acrylic adhesive A)
The acrylic polymer (I) solution (40%) is diluted to 4% with ethyl acetate, and 0.59 parts (solid content 0.3 parts) of the acrylic oligomer solution is added to 2500 parts (solid content 100 parts) of this solution. ) As a cross-linking agent, 1.0 part of hexamethylene diisocyanate isocyanurate (manufactured by Nippon Polyurethane Industry Co., Coronate HX) (solid content: 1.0 part), dibutyltin dilaurate (1% ethyl acetate) as a cross-linking catalyst Solution) 3 parts (solid content 0.03 part) and organopolysiloxane (KF-353, manufactured by Shin-Etsu Chemical Co., Ltd.) diluted to 10% with ethyl acetate (solid part 0.2 part) As an alkali metal salt which is an antistatic agent, lithium bis (trifluoromethanesulfone) imide (LiN (CF ₃ SO ₂ ) ₂ : LiTFSI, manufactured by Tokyo Chemical Industry Co., Ltd.) is acetic acid. 15 parts of a solution diluted to 1% with ethyl (0.15 part of solid content) was mixed and stirred to prepare an acrylic pressure-sensitive adhesive solution A.

2-1-4. Preparation of surface protective film Adhesive A obtained above was applied to the PET film surface of the laminate using a Meyer bar so that the thickness after drying would be 0.3 μm, and then hot air circulation It was made to dry at 130 degreeC for 1 minute in a type | formula oven, and the surface protection film 2-1 was obtained.

<Reference example 2-2> Surface protective film Except having used the following adhesive M, it carried out similarly to Reference example 2-1, and obtained the surface protective film 2-2.
(Urethane adhesive M)
As a polyol, 85 parts of Preminol S3011 (manufactured by Asahi Glass Co., Ltd., Mn = 10000) which is a polyol having three hydroxyl groups, 13 parts of Sanniks GP3000 (manufactured by Sanyo Chemical Co., Ltd., Mn = 3000) which is a polyol having three hydroxyl groups , Sanix GP1000 (manufactured by Sanyo Chemical Co., Ltd., Mn = 1000) which is a polyol having three hydroxyl groups, 10 parts of an isocyanate compound coronate HX (manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent, and iron (III) acetyl as a catalyst Acetonate (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.04 part and 1000 parts of ethyl acetate as a diluent solvent were blended to obtain a urethane-based adhesive solution M. In addition, as a raw material of a urethane type adhesive solution, all are materials with a density | concentration of 100% except a solvent.

<Reference Example 2-3> Surface protective film The surface protective film was treated in the same manner as Reference Example 2-1 except that the following pressure-sensitive adhesive C was used and the pressure-sensitive adhesive after application was dried at 150 ° C. for 2 minutes. A protective 2-3 film was obtained.
(Silicone adhesive C)
As a silicone-based pressure-sensitive adhesive, “X-40-3229” (solid content 60%, manufactured by Shin-Etsu Chemical Co., Ltd.) is 100 parts in solid content, and “CAT-PL-50T” (manufactured by Shin-Etsu Chemical Co., Ltd.) 0 as a platinum catalyst. .3 parts and 1200 parts of toluene as a solvent were blended to obtain a silicone-based pressure-sensitive adhesive solution C.

<Reference Example 2-4> Surface Protective Film A surface protective film 2-4 was obtained in the same manner as Reference Example 2-1, except that the following adhesive D was used.
(Rubber adhesive D)
A rubber-based adhesive solution D was prepared by dissolving styrene / isobutylene / styrene block copolymer (manufactured by Kaneka Corporation, Shibster 072T) in toluene.

<Reference Example 2-5> Surface protective film A surface protective film 2-5 was obtained in the same manner as in Reference Example 2-1, except that the thickness of the pressure-sensitive adhesive layer was 1.0 μm.

<Reference Example 2-6> Surface protective film A surface protective film 2-6 was obtained in the same manner as in Reference Example 2-1, except that the thickness of the pressure-sensitive adhesive layer was 5.0 μm.

<Reference Example 2-7> Surface Protective Film Reference Example 2 except that the PET film was changed to a trade name “Diafoil T100” manufactured by Mitsubishi Chemical Corporation with a thickness of 50 μm, and the thickness of the adhesive layer was changed to 15 μm. Surface protection film 2-7 was obtained in the same manner as -1.

<Reference Example 2-8> Surface Protective Film A surface protective film 2-8 was obtained in the same manner as Reference Example 2-1, except that the PET film was changed to T100 manufactured by Mitsubishi Chemical Corporation.

<Reference Example 2-9> Surface protective film A surface protective film 2-9 was obtained in the same manner as in Reference Example 2-8, except that the thickness of the pressure-sensitive adhesive layer was 0.15 μm.

<Reference Example 2-10> Surface Protective Film A surface protective film 2-10 was obtained in the same manner as in Reference Example 2-1, except that the thickness of the pressure-sensitive adhesive layer was 0.15 μm.

<Example 1>
The polarizing plate obtained in Reference Example 1-1 and the surface protective film obtained in Reference Example 2-1 were each punched into A4 size. Using the bonding roll, the punched polarizing plate and the surface protective film were bonded together via the pressure-sensitive adhesive layer of the surface protective film to obtain a polarizing plate with a surface protective film. The obtained polarizing plate with a surface protective film was subjected to the evaluations (3) to (4) above. The results are shown in Table 1.

<Examples 2-8 and Comparative Examples 1-5>
A polarizing plate with a surface protective film was obtained in the same manner as in Example 1 except that the polarizing plate and the surface protective film were bonded together in the combinations shown in Table 1. The obtained polarizing plate with a surface protective film was subjected to the same evaluation as in Example 1. The results are shown in Table 1. In Table 1, “SPV” indicates a surface protective film, and “1-2”, “2-5”, etc. indicate reference example numbers.

<Evaluation>
As is apparent from Table 1, the optical laminate with a surface protective film of the examples of the present invention achieves a very good high-speed peeling of the surface protective film, and is excellent in appearance because air bubbles are remarkably suppressed. Yes.

  The optical laminate with a surface protective film of the present invention is suitably used for various image display devices.

DESCRIPTION OF SYMBOLS 10 Optical laminated body 20 Surface protective film 21 Base material 22 Adhesive layer 100 Optical laminated body with a surface protective film

Claims (10)

Having an optical laminate and a surface protective film,
The surface protective film has a substrate and a pressure-sensitive adhesive layer, and is peelably bonded to the optical laminate through the pressure-sensitive adhesive layer.
The thickness of the pressure-sensitive adhesive layer of the surface protective film is 2 μm or less, and the surface roughness Sa ₁ of the pressure-sensitive adhesive layer is 30 nm or less,
The surface roughness Sa ₂ of the surface in contact with the pressure-sensitive adhesive layer of the optical laminate is 30 nm or less.
Optical laminate with surface protective film.   The optical laminate with a surface protective film according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 1 μm or less. The surface roughness Sa ₁ of the pressure-sensitive adhesive layer is 10nm or less, a surface protective film attached optical laminate according to claim 1 or 2. The surface roughness Sa ₂ of the surface in contact with the adhesive layer of the optical stack is 10nm or less, a surface protective film attached optical laminate according to any one of claims 1 to 3.   The optical laminated body with a surface protective film in any one of Claim 1 to 4 whose high speed peeling force is 0.20 N / 25mm or less.   The optical laminate with a surface protective film according to claim 1, wherein the surface protective film has a thickness of 15 μm to 60 μm.   The optical laminate with a surface protective film according to any one of claims 1 to 6, wherein the surface protective film further has an antistatic layer on a side opposite to the pressure-sensitive adhesive layer of the substrate.   The optical laminate with a surface protective film according to any one of claims 1 to 7, wherein a base resin of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is selected from a silicone-based resin, an acrylic resin, a urethane-based resin, and a rubber-based resin. body.   The optical laminated body with a surface protective film in any one of Claim 1 to 8 in which the said optical laminated body contains a polarizer. The optical laminate with a surface protective film according to claim 9, wherein the polarizer has a thickness of 3 μm to 30 μm.

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