CN111433025A - Polarizing plate, method for producing same, and image display device - Google Patents

Polarizing plate, method for producing same, and image display device Download PDF

Info

Publication number
CN111433025A
CN111433025A CN201980006231.4A CN201980006231A CN111433025A CN 111433025 A CN111433025 A CN 111433025A CN 201980006231 A CN201980006231 A CN 201980006231A CN 111433025 A CN111433025 A CN 111433025A
Authority
CN
China
Prior art keywords
easy
adhesive
layer
adhesion
film
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201980006231.4A
Other languages
Chinese (zh)
Inventor
冈田康彰
徐菁璠
品川雅
道下空
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nitto Denko Corp
Original Assignee
Nitto Denko Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=69412193&utm_source=***_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=CN111433025(A) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Nitto Denko Corp filed Critical Nitto Denko Corp
Priority claimed from PCT/JP2019/028169 external-priority patent/WO2020022164A1/en
Publication of CN111433025A publication Critical patent/CN111433025A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/0074—Production of other optical elements not provided for in B29D11/00009- B29D11/0073
    • B29D11/00788—Producing optical films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00865—Applying coatings; tinting; colouring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/308—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/325—Layered products comprising a layer of synthetic resin comprising polyolefins comprising polycycloolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B32B27/365—Layered products comprising a layer of synthetic resin comprising polyesters comprising polycarbonates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/0427—Coating with only one layer of a composition containing a polymer binder
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/50—OLEDs integrated with light modulating elements, e.g. with electrochromic elements, photochromic elements or liquid crystal elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/26—Polymeric coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/42—Polarizing, birefringent, filtering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/726—Permeability to liquids, absorption
    • B32B2307/7265—Non-permeable
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2475/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
    • C08J2475/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/318—Applications of adhesives in processes or use of adhesives in the form of films or foils for the production of liquid crystal displays
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/40—Additional features of adhesives in the form of films or foils characterized by the presence of essential components
    • C09J2301/416—Additional features of adhesives in the form of films or foils characterized by the presence of essential components use of irradiation

Landscapes

  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Nonlinear Science (AREA)
  • Mechanical Engineering (AREA)
  • Ophthalmology & Optometry (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Mathematical Physics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Polarising Elements (AREA)
  • Liquid Crystal (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Laminated Bodies (AREA)
  • Adhesive Tapes (AREA)
  • Electroluminescent Light Sources (AREA)
  • Inorganic Chemistry (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Paints Or Removers (AREA)

Abstract

The polarizing plate (100) is provided with an easily adhesive film (1) adhered to one main surface of a polyvinyl alcohol-based polarizing material (5) via an adhesive layer (6). The easy-adhesion film is provided with an easy-adhesion layer (15) on the surface of a transparent film base material (11), and the easy-adhesion layer is adhered to a polarizer. The adhesive layer is a cured layer of an active energy ray-curable adhesive. Preferably, an adhesive interface layer is present at the interface between the easy-adhesive layer and the adhesive layer, the adhesive interface layer being present in such a manner that the resin component of the easy-adhesive layer is compatible with the resin component of the adhesive layer.

Description

Polarizing plate, method for producing same, and image display device
Technical Field
The present invention relates to a polarizing plate in which an easily adhesive film is bonded to the surface of a polarizer, a method for manufacturing the same, and an image display device including the same.
Background
In the organic E L display device, a circularly polarizing plate (typically, a laminate of a polarizing plate and a 1/4 wavelength plate) is sometimes disposed on the viewing side surface in order to suppress reflection of external light by a metal electrode (cathode) and to be viewed as a mirror surface.
In general, a polarizing plate includes a transparent film (polarizer protective film) for the purpose of protecting a polarizer or the like on one or both sides of the polarizer. As a polarizer, a polarizer in which a polyvinyl alcohol (PVA) film is adsorbed with iodine and molecules are oriented by stretching or the like is widely used.
As a polarizer protective film to be bonded to the surface of a polarizer, a cellulose-based film such as cellulose acetate is widely used because of its excellent adhesiveness to a PVA-based polarizer. As the transparent protective film, a film made of a resin material such as acrylic, polyester, polycarbonate, or cyclic polyolefin is also used. Films formed of these resin materials have lower moisture permeability than cellulose films, and polarizing plates having a low moisture permeability resin film laminated on the surface of a polarizer tend to have less change in optical properties and excellent durability even when exposed to a high-humidity environment for a long time.
On the other hand, a film made of a resin material such as acrylic, polyester, polycarbonate, or cyclic polyolefin tends to have lower adhesiveness to a PVA-based polarizing material than a cellulose-based film. The following methods are therefore proposed: an easy-adhesion layer is provided on the surface of a transparent film used as a polarizer protective film, thereby improving the adhesion between the film and a polarizer.
For example, patent document 1 describes that an easy-adhesion film in which an easy-adhesion layer containing fine particles and a binder resin is provided on the surface of an acrylic film has excellent adhesion to a polarizer and can suppress blocking when the film is wound into a roll. In the examples of patent document 1, an example is shown in which an easy-adhesion film having an easy-adhesion urethane layer containing 1 to 7% by weight of silica fine particles and having an average thickness of 400nm (thickness range 300 to 500nm) on the surface of an acrylic film is bonded to a polarizer using an aqueous adhesive.
Documents of the prior art
Patent document
Patent document 1: japanese patent No. 5354733
Disclosure of Invention
Problems to be solved by the invention
In the process of increasing the size and brightness of an image display device, a polarizing plate constituting the image display device is required to have less interlayer peeling at an interface and less change in optical characteristics even in a severer environment (for example, under a condition of higher temperature and higher humidity). Accordingly, the polarizer and the polarizer protective film are bonded to each other using an active ray-curable adhesive that is cured by light irradiation or electron beam irradiation.
The invention provides a polarizing plate which has excellent adhesion between a polarizer and a polarizer protective film, is less prone to interlayer peeling even exposed to a high-temperature and high-humidity environment for a long time, and has excellent cutting processability.
Means for solving the problems
The present invention relates to a polarizing plate in which an easy-adhesive film and a polarizer are bonded to each other via an adhesive layer, and a method for manufacturing the same. The easy-adhesion film has an easy-adhesion layer on the surface of a transparent film base. The easy-adhesion layer contains a binder resin and inorganic particles having an average primary particle diameter of 10 to 100 nm. The content of the alkaline component of the easy-bonding layer is preferably 5-75 ppm, and the thickness of the easy-bonding layer is preferably 40-280 nm.
As the transparent film substrate, an acrylic film or the like is used. As the binder resin of the easy adhesion layer, urethane resin or the like is used. The content of the inorganic fine particles in the easy-adhesion layer is preferably about 8 to 50 wt%. The inorganic fine particles of the easy-adhesion layer may be embedded in the transparent film base.
An easy-adhesion layer is formed by applying an easy-adhesion composition to the surface of a transparent film substrate and heating the composition. The easy-adhesion composition contains a binder resin or a precursor thereof, inorganic fine particles having an average primary particle diameter of 10 to 100nm, an alkaline component and a solvent. When the easy-adhesion composition contains an alkaline component, the dispersibility of the inorganic fine particles is improved, and an easy-adhesion film having excellent sliding properties can be obtained. The basic component may also function as a catalyst for promoting the reaction of the binder resin (precursor). The boiling point of the alkali component is preferably 150 ℃ or lower from the viewpoint of promoting the volatilization of the alkali component by heating. Examples of the basic component include amines and ammonia.
By increasing the heating temperature after the application of the easy-adhesion composition, volatilization of the alkali component is promoted, and an easy-adhesion layer having a small amount of residual alkali component can be formed. For example, the easy adhesion composition may be heated at a temperature higher by 10 ℃ or more than the glass transition temperature of the transparent film substrate. By raising the heating temperature, a region in which the inorganic fine particles of the easy-adhesion layer are embedded in the transparent film base is easily formed, and the adhesion between the transparent film base and the easy-adhesion layer tends to be improved.
After the easy-adhesion composition is applied to the transparent film base material, the transparent film base material may be stretched while being heated. In particular, the adhesion between the transparent film base and the easy-adhesive layer tends to be improved by stretching the transparent film base while heating the easy-adhesive composition at a temperature higher by 10 ℃ or more than the glass transition temperature of the transparent film base.
The above easy-adhesion film can be used as a polarizer protective film. The polarizing plate can be obtained by attaching an easily adhesive film to the surface of a polyvinyl alcohol-based polarizing material via an adhesive layer. The adhesive is preferably an active energy ray-curable adhesive. After the adhesive is cured, an adhesive interface layer in which the resin component of the easy-adhesion layer and the resin component of the adhesive layer are compatible with each other is preferably present at the interface between the easy-adhesion layer and the adhesive layer. The thickness of the adhesive interface layer is preferably 40nm or more, and the thickness of the portion of the adhesive layer other than the adhesive interface layer is preferably 120nm or more.
The thickness of the adhesive layer (the total thickness of the adhesive layer and the adhesive interface layer) is preferably 0.3 to 3 μm. The thickness of the adhesive interface layer is preferably 5 to 90% of the total thickness of the adhesive layer and the adhesive interface layer.
An image display device can be formed by disposing a polarizing plate on the surface of an image display cell such as a liquid crystal display cell or an organic E L cell.
ADVANTAGEOUS EFFECTS OF INVENTION
The polarizing plate of the present invention is excellent in adhesion between the polarizer and the easy-adhesion film. Further, the occurrence of micro-cracks during cutting is small, and the cutting workability is excellent.
Drawings
Fig. 1 is a sectional view showing a configuration example of an easy-adhesion film.
Fig. 2 is a cross-sectional view showing an example of the structure of the polarizing plate, and an enlarged view shows an example of the layer structure of the adhesion interface between the polarizing material and the easy adhesion film.
Fig. 3 is a cross-sectional TEM image of an easy-adhesion film in which a substrate interface layer is formed at the interface between the film substrate and the easy-adhesion layer.
Fig. 4 is a cross-sectional TEM image of an easy-adhesion film in which a substrate interface layer is not formed at the interface between the film substrate and the easy-adhesion layer.
Fig. 5 is a photograph showing cross prism observations before and after a durability test of the polarizing plate.
Fig. 6 is a cross-sectional TEM observation image of a polarizing plate in which an adhesive interface layer is formed at the interface between the easy-adhesive layer and the adhesive layer.
Detailed Description
Fig. 1 is a schematic cross-sectional view showing a configuration example of an easy-adhesion film. The easy-adhesion film 1 includes an easy-adhesion layer 15 on at least one surface of a film base 11. The film base material may be provided with an easy-adhesion layer on both sides thereof. The easy-adhesion film may be used by bonding to other films, a glass substrate, or the like.
The easy-adhesion film may be used in a polarizer protective film. Fig. 2 is a cross-sectional view showing an example of the structure of a polarizing plate including the easy-adhesion film 1 as a polarizer protective film. The polarizing plate 100 includes an easy-adhesion film 1 bonded to one surface (first main surface) of a polarizer 5 via an adhesive layer 6. In the polarizing plate 100 shown in fig. 2, the easy-adhesion film 1 has an easy-adhesion layer 15 on the surface of the film base 11 that is in contact with the polarizer 5. An adhesive layer may be provided on the surface to which the polarizer 5 is not attached. In the polarizing plate 100 shown in fig. 2, a transparent protective film 2 is bonded to the other surface (second main surface) of the polarizer 5 via an adhesive layer 7.
[ easy adhesion film ]
The easy-adhesion film 1 includes an easy-adhesion layer 15 on at least one surface of a film base 11.
< film substrate >
As the film substrate 11, a transparent film is preferable. The total light transmittance of the transparent film substrate is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. Examples of the resin material constituting the film base 11 include acrylic resins, polyester resins, polycarbonate resins, polyolefin resins, cyclic polyolefin resins, polystyrene resins, polyamide resins, polyimide resins, and the like. When the easy-adhesion film is used as an optically isotropic polarizer protective film, an acrylic resin or a cyclic polyolefin resin is preferable, and an acrylic resin is particularly preferable, from the viewpoint of low birefringence, as a resin material of the film base 11.
Examples of the cyclic polyolefin resin include polynorbornene, and commercially available cyclic polyolefin resins include ZEONOR and ZEONEX manufactured by Zeon Corporation, ARTON manufactured by JSR Corporation, APE L manufactured by mitsui chemicals, inc., and TOPAS manufactured by TOPAS Advanced Polymers.
Examples of the acrylic resin include poly (meth) acrylates such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymers, methyl (meth) acrylate-styrene copolymers (MS resins, etc.), and polymers having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymers, methyl methacrylate- (meth) acrylic acid norbornyl ester copolymers, etc.).
In the present specification, "(meth) acrylic acid" means acrylic acid and/or methacrylic acid. The acrylic resin includes a resin containing acrylic acid or a derivative thereof as a constituent monomer component and a resin containing methacrylic acid or a derivative thereof as a constituent monomer component.
As the acrylic resin, acrylic resins having a glutaric anhydride structure described in japanese patent application laid-open nos. 2006-283013, 2006-335902, and 2006-274118; and/or acrylic resins having a lactone ring structure described in Japanese patent laid-open Nos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, 2005-146084, and the like. Acrylic resins having a glutaric anhydride structure and acrylic resins having a lactone ring structure have high heat resistance, high transparency, and high mechanical strength, and therefore, are suitable for producing a polarizing plate having high polarization degree and excellent durability.
When the film base 11 is an acrylic film, the content of the acrylic resin in the film base is preferably 50% by weight or more, more preferably 60 to 98% by weight, and still more preferably 70 to 97% by weight. The acrylic film may contain a thermoplastic resin other than the acrylic resin. For example, an acrylic film having excellent optical isotropy can be obtained by adding another thermoplastic resin to eliminate birefringence of the acrylic resin. In addition, a thermoplastic resin other than an acrylic resin may be blended for the purpose of improving the mechanical strength of the film or the like.
Examples of the thermoplastic resin other than the acrylic resin include olefin polymers, halogenated vinyl polymers, polystyrene, copolymers of styrene and acrylic monomers, polyesters, polyamides, polyacetals, polycarbonates, polyphenylene ethers, polyphenylene sulfides, polyether ether ketones, polysulfones, polyether sulfones, polyoxybenzyls (polyoxybenzylenes), polyamide imides, rubber polymers, and the like.
The film base 11 may contain additives such as antioxidants, stabilizers, reinforcing materials, ultraviolet absorbers, flame retardants, antistatic agents, colorants, fillers, plasticizers, lubricants, fillers, and the like. The resin material may be mixed with additives or the like to prepare a thermoplastic resin composition such as pellets in advance and then the mixture may be made into a film.
The film base material 11 has a thickness of about 5 to 200 μm. The film base 11 preferably has a thickness of 10 to 100 μm, more preferably 15 to 60 μm, from the viewpoints of mechanical strength, transparency, handleability, and the like.
The glass transition temperature Tg of the film substrate 11 is preferably 100 ℃ or higher, and more preferably 110 ℃ or higher. When the film substrate 11 is an acrylic film, as described above, the Tg of the acrylic film can be increased and the heat resistance can be improved by using an acrylic resin having a glutaric anhydride structure or an acrylic resin having a lactone ring structure as the acrylic resin. The upper limit of Tg of the film base material 11 is not particularly limited, but is preferably 170 ℃ or lower from the viewpoint of moldability and the like.
Examples of the method for producing the film base material 11 include a solution casting method, a melt extrusion method, a rolling method, a compression molding method, and the like. The film substrate 11 may be an unstretched film or a stretched film. When the film substrate 11 is an acrylic film, the acrylic film is preferably a stretched film stretched in at least 1 direction, and particularly preferably a biaxially stretched film, from the viewpoint of improving mechanical strength. In order to eliminate the birefringence of the acrylic resin, an acrylic film having a small retardation even when stretched and excellent optical isotropy can be obtained by blending another thermoplastic resin.
< easy adhesion layer >
The easy-adhesion layer 15 provided on the surface of the film base 11 contains a binder resin and fine particles. By providing the easy-adhesion layer 15, adhesion to a film such as a polarizer, a glass substrate, or the like can be improved. The easy-adhesion layer 15 contains fine particles, so that fine irregularities are formed on the surface of the easy-adhesion layer 15, and the slip property of the film is improved. This contributes to reducing scratches on the easy-to-adhere film 1 during roll transportation and suppressing blocking when wound into a roll.
(Binder resin)
As the binder resin, a resin (polymer) having a reactive group such as a polyurethane resin, an epoxy resin, an isocyanate resin, a polyester resin, a polymer containing an amino group in a molecule, or an acrylic resin having a crosslinkable functional group such as an oxazoline group can be used in view of excellent adhesion to a film base such as an acrylic film. As the binder resin of the easy-adhesion layer 15, a polyurethane resin is particularly preferable. The easy-adhesion layer 15 containing a urethane resin binder has high adhesion to the film base 11. The easy-adhesion film 1 in which the easy-adhesion layer 15 contains a urethane resin adhesive tends to exhibit high adhesiveness when laminated with a film such as a polarizer via an adhesive layer.
Urethane resins are typically the reaction product of a polyol and a polyisocyanate. As the polyol component, a polymer polyol such as a polyacrylic polyol, a polyester polyol, and a polyether polyol is preferably used.
Polyacrylic polyols are typically obtained by polymerization of (meth) acrylates with hydroxyl-containing monomers. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate. Examples of the hydroxyl group-containing monomer include hydroxyalkyl esters of (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxypentyl (meth) acrylate; (meth) acrylic acid monoesters of polyhydric alcohols such as glycerin and trimethylolpropane; n-methylol (meth) acrylamide and the like.
The other monomer components include unsaturated monocarboxylic acids such as (meth) acrylic acid, unsaturated dicarboxylic acids such as maleic acid and anhydrides and diesters thereof, (unsaturated nitriles such as (meth) acrylonitrile, (unsaturated amides such as (meth) acrylamide and N-methylol (meth) acrylamide), vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as methyl vinyl ether, α -olefins such as ethylene and propylene, halogenated α -unsaturated aliphatic monomers such as vinyl chloride and vinylidene chloride, and α -unsaturated aromatic monomers such as styrene and α -methylstyrene.
Polyester polyols are typically obtained by the reaction of a polybasic acid with a polyhydric alcohol. Examples of the polybasic acid include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1, 4-naphthalenedicarboxylic acid, 2, 5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, tetrahydrophthalic acid, and the like; aliphatic dicarboxylic acids such as oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkylsuccinic acid, linolenic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, and itaconic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid, 1, 3-cyclohexanedicarboxylic acid, and 1, 4-cyclohexanedicarboxylic acid; or reactive derivatives thereof such as acid anhydrides, alkyl esters, and acid halides.
Examples of the polyhydric alcohol include ethylene glycol, 1, 2-propanediol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, pentanediol, 1, 6-hexanediol, 1, 8-octanediol, 1, 10-decanediol, 1-methyl-1, 3-butanediol, 2-methyl-1, 3-butanediol, 1-methyl-1, 4-pentanediol, 2-methyl-1, 4-pentanediol, 1, 2-dimethyl-neopentyl glycol, 2, 3-dimethyl-neopentyl glycol, 1-methyl-1, 5-pentanediol, 2-methyl-1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 1, 4-butanediol, 1, 3-methyl-1, 5-pentanediol, 1, 4-butanediol, 1, 3-octanediol, 1, 3-methyl-1, 5-pentanediol, 1, 2-dimethylbutylene glycol, 1, 3-dimethylbutylene glycol, 2, 3-dimethylbutylene glycol, 1, 4-dimethylbutylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1, 4-cyclohexanedimethanol, 1, 4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, and the like.
Polyether polyols are typically obtained by ring-opening polymerization of alkylene oxides and addition to polyols. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, and trimethylolpropane. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and tetrahydrofuran.
Examples of the polyisocyanate include aliphatic diisocyanates such as tetramethylene diisocyanate, dodecamethylene diisocyanate, 1, 4-butane diisocyanate, hexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2,4, 4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1, 5-diisocyanate and 3-methylpentane-1, 5-diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4 ' -cyclohexylmethane diisocyanate, 1, 4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate and 1, 3-bis (isocyanatomethyl) cyclohexane, alicyclic diisocyanates such as toluene diisocyanate, 2 ' -diphenylmethane diisocyanate, 2,4 ' -diphenylmethane diisocyanate, 4,4 ' -diphenyldimethylmethane diisocyanate, 4,4 ' -dibenzyl diisocyanate, 1, 5-naphthylene diisocyanate, xylylene diisocyanate, 1, 3-phenylene diisocyanate and 1, 4-phenylene diisocyanate, aromatic diisocyanates such as tetramethyldiphenylmethane diisocyanate and α.
The urethane resin constituting the easy adhesion layer 15 preferably has a carboxyl group. The urethane resin having a carboxyl group can introduce a crosslinked structure, and tends to improve the adhesion durability between the easy-to-adhere film 1 and a polarizer or the like. The urethane resin having a carboxyl group can be obtained, for example, by reacting a chain extender having a free carboxyl group on the basis of a polyol and a polyisocyanate resin. Examples of the chain extender having a free carboxyl group include dihydroxycarboxylic acid, dihydroxysuccinic acid and the like. Examples of the dihydroxy carboxylic acid include dialkyl alkanoic acids such as dimethylol alkanoic acids (e.g., dimethylol acetic acid, dimethylol butyric acid, dimethylol propionic acid, dimethylol butyric acid, and dimethylol valeric acid).
The method for producing the urethane resin is not particularly limited, and may be any of a one-step method in which monomer components are reacted at once and a multi-step method in which the monomer components are reacted at once. When a chain extender having a free carboxyl group is used to introduce a carboxyl group into a urethane resin, a multistage method is preferable. When producing a urethane resin, a urethane reaction catalyst may be used as needed.
The number average molecular weight of the urethane resin is preferably 5000 to 600000, and more preferably 10000 to 400000. The acid value of the urethane resin is preferably 10 to 50, and more preferably 20 to 45.
The urethane resin may have a cross-linked structure. By introducing a crosslinked structure into the urethane resin, the adhesion durability between the easy adhesion film 1 and the polarizer 5 tends to be improved. As the crosslinking agent, a crosslinking agent capable of reacting with a crosslinkable functional group of the urethane resin can be used without particular limitation. When the urethane resin has a carboxyl group, a crosslinking agent containing an amino group, an oxazoline group, an epoxy group, a carbodiimide group, or the like can be used. Among these, a crosslinking agent having an oxazoline group is preferable. Since the oxazoline group has low reactivity with a carboxyl group at normal temperature, the pot life when it is mixed with a urethane resin is long, and the lead time (lead time) of the process can be flexibly coped with.
The crosslinking agent may be a low-molecular compound or a polymer. The crosslinking agent is preferably an acrylic polymer because of its high solubility in an aqueous composition and excellent compatibility with a urethane resin. In particular, when an oxazoline group-containing acrylic polymer is used as a crosslinking agent, the adhesiveness between the easy-to-adhere film 1 and a film such as a polarizer tends to be improved.
The amount of the crosslinking agent used is preferably 1 to 30 parts by weight, more preferably 3 to 20 parts by weight, based on 100 parts by weight of the urethane resin.
(Fine particles)
By forming fine irregularities on the surface of the easy-adhesion layer by including fine particles in the easy-adhesion layer 15, the slip property of the easy-adhesion film 1 is improved, and blocking can be suppressed. From the viewpoint of forming irregularities contributing to improvement in sliding properties, the particle diameter (average primary particle diameter) of the fine particles is preferably 10nm or more, more preferably 15nm or more, and still more preferably 20nm or more. By making the average primary particle size of the fine particles smaller than the wavelength of visible light, scattering of visible light at the interface between the binder resin and the fine particles can be suppressed, and an easily adhesive film having high transparency can be obtained. Therefore, the particle diameter of the fine particles is preferably 100nm or less, more preferably 80nm or less, further preferably 60nm or less, and particularly preferably 50nm or less.
The fine particles of the easy-adhesion layer 15 are preferably inorganic fine particles because of excellent dispersibility and uniformity of particle size. Examples of the inorganic fine particles include inorganic oxides such as titanium oxide, aluminum oxide, and zirconium oxide; calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and the like. Among these, inorganic oxides are preferable. In order to suppress light scattering by the fine particles, the difference in refractive index between the binder resin (generally having a refractive index of about 1.5) and the fine particles is preferably small. Silica particles are preferable as the fine particles of the easy-adhesion layer 15 because of a small difference in refractive index with the binder resin and excellent dispersibility.
When the easy-adhesion layer 15 is formed of an aqueous composition, fine particles having high water dispersibility are preferably used. An aqueous dispersion of fine particles may be blended in the composition. In order to improve the dispersibility of the fine particles, it is preferable to make the easy-to-bond composition weakly alkaline by adding a basic component such as amine or ammonia.
As the colloidal silica, commercially available products such as Quarton. P L series manufactured by Hibiscus chemical Co., Ltd, Snowtex series manufactured by Nissan chemical industry Co., Ltd, AERODISP series manufactured by NIPPON AEROSI L Co., L td., and AEROSI L series can be used.
The content of the fine particles in the easy-adhesive layer 15 is preferably 8 wt% or more, more preferably 10 wt% or more, and even more preferably 12 wt% or more, from the viewpoint of improving the slidability of the easy-adhesive film 1 by forming the irregularities on the surface of the easy-adhesive layer 15. In particular, when the thickness of the easy-adhesion layer 15 is 280nm or less, it is preferable to increase the content of the fine particles to increase the amount (number density) of the fine particles per unit area, thereby uniformly forming irregularities in the surface of the easy-adhesion layer 15. If the content of the fine particles in the easy-adhesion layer 15 is too large, light scattering at the interface between the binder resin and the fine particles may increase, and optical characteristics may be degraded. Further, as the content of the fine particles increases, the relative content of the binder resin decreases, and thus the adhesiveness of the adhesive layer may be easily decreased. Therefore, the content of the fine particles in the easy-adhesion layer 15 is preferably 50 wt% or less, more preferably 40 wt% or less, and further preferably 30 wt% or less.
(residual alkali amount)
When an alkaline component such as amine or ammonia is used to improve the dispersibility of the inorganic fine particles, the alkaline component inevitably remains in the adhesive layer. When the easy-adhesion film 1 is used as a polarizer protective film, if the residual alkaline component of the easy-adhesion layer 15 is eluted by moisture or the like, the polarizer may be deteriorated, and optical defects such as a reduction in the polarization degree of the polarizing plate and stripe-like unevenness may occur.
The amount of residual alkali in the easy-adhesive layer 15 is preferably 75ppm or less, more preferably 70ppm or less, still more preferably 60ppm or less, and particularly preferably 55ppm or less, from the viewpoint of improving the humidification durability of the polarizing plate. From the viewpoint of improving the humidification durability of the polarizing plate, the amount of the residual alkali in the easy-adhesive layer 15 is preferably smaller.
On the other hand, when the amount of the residual alkali in the easy-adhesion layer 15 is too small, dispersibility of the fine particles is impaired, and appearance defects such as cloudiness due to aggregation of the fine particles may occur. Further, since the fine particles aggregate and fall off from the easy-adhesion layer due to the decrease in dispersibility, appropriate irregularities are not formed on the surface of the easy-adhesion layer, and the slip property of the easy-adhesion film tends to decrease. Therefore, the amount of the residual alkali in the easy-adhesion layer 15 is preferably 5ppm or more, more preferably 10ppm or more, and still more preferably 20ppm or more.
The amount of the base in the easy adhesion layer can be determined by liquid chromatography, ion chromatography, or the like depending on the type of the base component, the amount of the base component can be determined by an analytical method (for example, L C/MS) in which chromatography and Mass Spectrometry (MS) are combined, and when a plurality of base components are contained in the easy adhesion layer, the total amount of each component is defined as the base component content (residual amount) of the easy adhesion layer.
< formation of easy adhesion layer >
The method for forming the easy-adhesion layer 15 on the surface of the film base 11 is not particularly limited. The easy-adhesion layer 15 is preferably formed by applying an easy-adhesion composition (coating liquid) containing a binder resin and fine particles on the film base 11 and heating the composition.
(easy adhesion composition)
The easy-adhesion composition is preferably an aqueous composition containing water as a solvent (and a dispersion medium for fine particles). The concentration of the solid content (nonvolatile content) in the easy-adhesion composition is preferably 1 to 30% by weight, more preferably 2 to 20% by weight, and still more preferably 3 to 15% by weight.
The aqueous easy-adhesion composition contains water as a solvent (and a dispersion medium), a binder resin or a precursor thereof, and inorganic fine particles. The easy adhesion composition preferably further comprises an alkaline component. As described above, the alkali component has an action of promoting dispersion of the inorganic fine particles. Therefore, the easy-adhesion composition containing the basic component can improve the dispersibility of the inorganic fine particles, and can provide an easy-adhesion film having excellent appearance and sliding properties.
On the other hand, if the base contained in the easy-adhesion composition remains in the easy-adhesion layer, the base may cause a decrease in the moist heat resistance of the polarizing plate. In particular, a strong alkali such as caustic alkali causes deterioration of the polarizer even when a small amount of the alkali is used. Therefore, as the basic component contained in the easy-adhesion composition, a weakly basic component such as ammonia or amine is preferable. From the viewpoint of improving the dispersibility of the inorganic fine particles and preventing the deterioration of the polarizing plate, the pH of the easy-adhesion composition (coating liquid) is preferably about 7.5 to 9.
From the viewpoint of improving the dispersibility of the inorganic fine particles, the amount of the basic component contained in the easy-to-bond composition is preferably 300ppm or more, and more preferably 500ppm or more, relative to the solid content of the easy-to-bond composition. On the other hand, when the content of the alkali component is too large, it may be difficult to reduce the amount of the residual alkali, and therefore the amount of the alkali component contained in the easy-adhesion composition is preferably 50000ppm or less, more preferably 10000ppm or less, and further preferably 5000ppm or less, relative to the solid content of the easy-adhesion composition.
The basic component contained in the easy-adhesion composition has a catalytic action and the like in addition to improving the dispersibility of the inorganic fine particles. For example, when the binder resin is a urethane resin, the easy adhesion composition may contain a tertiary amine such as triethylamine as a urethane-forming catalyst for a polyurethane precursor (e.g., a polyol or an isocyanate).
By applying the easy-adhesion composition to the film base and heating the film base, the alkali component can be volatilized and removed, and the residual alkali component in the easy-adhesion layer 15 can be reduced. The alkali component contained in the easy-adhesion composition preferably has a boiling point of 150 ℃ or less from the viewpoint of promoting volatilization of the alkali component by heating. The boiling point of the basic component is more preferably 130 ℃ or lower, still more preferably 120 ℃ or lower, and particularly preferably 110 ℃ or lower. The boiling point of the basic component may be 100 ℃ or lower or 90 ℃ or lower. When a plurality of basic components are contained in the easy-adhesion composition, the boiling point of at least 1 basic component is preferably in the above range, and the boiling point of 2 or more basic components is preferably in the above range. The boiling point of the alkali component is preferably 50 wt% or more with respect to 100 parts by weight of the total amount of the alkali contained in the easy-adhesion layer. It is desirable that the boiling point of all the alkali components contained in the easy-adhesion composition is within the above range.
The easy-adhesion composition may contain a crosslinking agent in addition to the binder resin (or its precursor), the inorganic fine particles, and the alkali component. The easy-adhesion composition may contain a catalyst such as a crosslinking accelerator, an antioxidant, an ultraviolet absorber, a leveling agent, an antiblocking agent, an antistatic agent, a dispersion stabilizer, an antifoaming agent, a thickener, a dispersant, a surfactant, a lubricant, and the like.
(formation of easy adhesion layer on film substrate)
Before the easy-adhesion composition is applied to the film base 11, the surface of the film base may be treated. By performing the surface treatment, the wetting tension of the film base material can be adjusted and the adhesion to the easy-adhesive layer 15 can be improved. Examples of the surface treatment include corona treatment, plasma treatment, ozone blowing, ultraviolet irradiation, flame treatment, and chemical treatment. Among these, corona treatment or plasma treatment is preferable.
Examples of the method for applying the easy-adhesion composition include bar coating, roll coating, gravure coating, bar coating, slot coating, curtain coating, and jet coating. The solvent is removed by heating the easy-adhesion composition after coating, thereby forming the easy-adhesion layer 15. The precursor material of the binder resin may be cured by reaction with heat. For example, in the case where the easy-adhesion composition contains a crosslinking agent, the crosslinking reaction can be promoted by heating. .
The heating temperature for forming the easy adhesion layer is, for example, about 50 to 200 ℃. The heating temperature is preferably 100 ℃ or higher, more preferably 120 ℃ or higher, further preferably 130 ℃ or higher, and particularly preferably 135 ℃ or higher, from the viewpoint of promoting the curing reaction of the resin component in the easy-adhesion composition and efficiently volatilizing and removing the alkali component contained in the adhesion composition. The heating temperature is preferably higher than the boiling point of the alkali component contained in the easy-adhesion composition.
The heating temperature for forming the easy-adhesion layer is preferably higher than the glass transition temperature (Tg) of the film base material. By heating at a high temperature, the curing reaction of the resin component in the easy-adhesion composition can be promoted, and the alkali component contained in the easy-adhesion composition can be efficiently volatilized and removed. The heating temperature is preferably 10 ℃ or higher than the Tg of the film base.
It is considered that heating at a temperature higher than Tg of the film base improves the efficiency of removing the alkali in the easy-adhesion composition by volatilization, and the easy-adhesion composition easily penetrates into the surface of the film base, thereby improving the adhesion between the film base 11 and the easy-adhesion layer 15. The heating temperature is preferably Tg +10 ℃ or higher, more preferably Tg +15 ℃ or higher, and still more preferably Tg +20 ℃ or higher of the film base material, from the viewpoint of improving the adhesion of the easy-adhesion layer.
When the film base is heated at a temperature of Tg +10 ℃ or higher, the film base changes from a glass state to a rubber state, and the surface is easily deformed, so that a base interface layer 18 (see the enlarged view of fig. 2) in which the resin component of the film base and the constituent component of the easy-adhesion layer are mixed is easily formed at the interface between the film base 11 and the easy-adhesion layer 15. By forming the substrate interface layer, the adhesion between the film substrate 11 and the easy-adhesive layer 15 tends to be improved.
In particular, as shown in the cross-sectional observation image of fig. 3, when there is a region where fine particles of the easy-adhesion layer 15 are embedded in the surface of the film base 11, an easy-adhesion film having high adhesion between the film base 11 and the easy-adhesion layer 15 can be obtained. It is considered that when the fine particles are embedded in the film base in a rubber state in which the film base is heated to a temperature higher than Tg and then the film base is returned to a glass state, the fine particles embedded in the surface of the film base and the binder resin present around the fine particles are fixed to the surface of the film base, and therefore the adhesion between the film base 11 and the easy-adhesive layer 15 is improved.
The easy-adhesion layer may be formed in the process of manufacturing the film base. Further, the easy-adhesion layer may be formed by heating when the film base is formed. For example, when the film substrate is a stretched film, the surface of the film before stretching or the surface of the film after longitudinal stretching is coated with an easy-adhesion composition, and the solvent can be dried and the resin can be cured by heating in transverse stretching or simultaneous biaxial stretching by a tenter.
In the case where the film base material is stretched after the application of the easy-adhesion composition, the stretching magnification is preferably 5 times or less, more preferably 4 times or less, further preferably 3 times or less, and particularly preferably 2.5 times or less, from the viewpoint of suppressing the occurrence of defects such as cracking in the easy-adhesion layer. The lower limit of the stretch ratio is not particularly limited, but the stretch ratio is preferably 1.3 times or more, and more preferably 1.5 times or more, from the viewpoint of enhancing the film strength. When the film base material is an acrylic film, it is preferable to stretch the film at the above-described stretch ratios in the Machine Direction (MD) and the width direction (TD), respectively, from the viewpoint of improving the film strength.
In the case of biaxially stretching the film base material, the biaxial stretching may be sequential biaxial stretching or simultaneous biaxial stretching. In addition, oblique stretching may also be performed. In the case of sequential biaxial stretching, the film may be stretched in 1 direction (MD) by roll stretching as described above, and then the easy-adhesion composition may be applied to the film, and the easy-adhesion composition may be heated during stretching by a tenter.
The stretching temperature is preferably higher than the Tg of the film base material, preferably Tg +10 ℃ or higher, more preferably Tg +15 ℃ or higher, and still more preferably Tg +20 ℃ or higher, as described above as the heating temperature of the easy-adhesion layer. Particularly preferably, after the easy-adhesion composition is applied, stretching is performed in at least 1 direction at the above temperature. When the film base is stretched in a rubber state at a temperature higher than Tg of the film base, a region where fine particles in the easily adhesive composition are embedded in the surface of the film base is easily formed, and adhesion between the film base 11 and the easily adhesive layer 15 tends to be improved. The reason why fine particles are easily embedded in the film base material by stretching at a high temperature includes: when the film base material is stretched in a rubber state, the easy-adhesion composition is likely to be wetted and spread when the film base material is deformed, and the fine particles are likely to be embedded in the concave portions of the surface irregularities formed when the film base material is deformed. Further, it is considered that when cooling is performed after stretching while releasing the stress, the particles embedded in the surface of the film base are fixed when the film base contracts, and therefore, a region in which fine particles are embedded in the film base is easily formed.
The thickness of the easy-adhesion layer 15 can be adjusted by adjusting the solid content concentration and the coating thickness of the easy-adhesion composition. In the case where the film base material is stretched after the application of the easy-adhesion composition, the thickness of the easy-adhesion layer 15 can be adjusted by the stretching ratio.
The thickness of the easy adhesion layer 15 is not particularly limited, but is preferably 280nm or less, more preferably 250nm or less, and further preferably 230nm or less, from the viewpoint of promoting removal of the alkali component by heating. When the easy-adhesion film 1 is used as a polarizer protective film, the thickness of the easy-adhesion layer 15 tends to be smaller, the humidification durability of the polarizing plate tends to be higher, and the occurrence of optical defects such as streaks tends to be reduced. Further, as the thickness of the easy-adhesion layer 15 is smaller, the decrease in the polarization degree of the polarizing plate when exposed to a humidified environment tends to be suppressed.
When the alkali component is excessively removed during the heat drying of the easy-adhesion composition, the dispersibility of the fine particles in the binder resin is lowered, and aggregation of the fine particles and the accompanying detachment of the fine particles from the surface of the easy-adhesion layer are likely to occur. When the particles are aggregated and dropped, the slidability of the adhesive film is reduced, and the adhesive film is easily scratched during conveyance and stuck during winding. Therefore, the thickness of the easy adhesion layer 15 is preferably 40nm or more, more preferably 50nm or more, further preferably 80nm or more, and particularly preferably 100nm or more. The thickness of the easy adhesion layer 15 is also preferably within the above range from the viewpoint of properly exhibiting the effect of improving adhesion by the easy adhesion layer 15.
[ polarizing plate ]
The polarizing plate may have a transparent protective film on only one side of the polarizer, or may have transparent protective films on both sides of the polarizer 5 as shown in fig. 2. By bonding the above-described easy-adhesion film as a polarizer protective film to one surface of a polarizer, a polarizing plate having a transparent protective film only on one surface of the polarizer can be formed. In the polarizing plate having the polarizer protective film on both surfaces of the polarizer, the easy-adhesion film may be bonded to at least one surface of the polarizer. The polarizing plate may be one in which the above-described easily adhesive film is bonded to both surfaces of a polarizing material. The polarizer 5 and the easy-adhesion film 1 are bonded to each other via an adhesive layer 6.
< polarizing plate >
As the polarizer 5, a polyvinyl alcohol (PVA) -based polarizer in which a dichroic material such as iodine or a dichroic dye is adsorbed to a polyvinyl alcohol-based film such as polyvinyl alcohol or partially formalized polyvinyl alcohol and oriented in 1 direction can be used. For example, a PVA-based polarizer can be obtained by subjecting a polyvinyl alcohol-based film to iodine dyeing and stretching.
In the process of producing the polarizer 5, treatments such as washing with water, swelling, and crosslinking may be performed as necessary. The stretching may be performed before or after the iodine dyeing, or may be performed while dyeing. The stretching may be any of stretching in air (dry stretching) or stretching in water or an aqueous solution containing boric acid, potassium iodide, or the like (wet stretching), and these may be used in combination. The thickness of the polarizer 5 is not particularly limited, but is generally about 1 to 50 μm.
As the polarizer 5, a thin PVA-based polarizer having a thickness of 10 μm or less may be used. Examples of the thin polarizers include those described in jp-a-51-069644, jp-a-2000-338329, WO2010/100917, japanese patent No. 4691205, and japanese patent No. 4751481. These thin polarizers can be obtained by a production method including a step of stretching a PVA-based resin layer and a stretching resin base material in a laminated state and a step of iodine dyeing. In this production method, even if the PVA-based resin layer is thin, it can be stretched without causing troubles such as breakage due to stretching because it is supported by the resin base material for stretching.
< adhesive agent >
The material of the adhesive layer 6 for bonding the polarizer 5 and the easy-adhesion film 1 is not particularly limited as long as it is optically transparent, and examples thereof include epoxy-based resins, silicone-based resins, acrylic-based resins, polyurethanes, polyamides, polyethers, polyvinyl alcohols, and the like. The thickness of the adhesive layer 6 is, for example, about 0.01 to 20 μm, and can be set appropriately according to the kind of adherend, the material of the adhesive, and the like. When a curable adhesive exhibiting adhesiveness by a crosslinking reaction after coating is used, the thickness of the adhesive layer 6 is preferably 0.01 to 5 μm, and more preferably 0.03 to 3 μm.
As the adhesive, various types of adhesives such as aqueous adhesives, solvent adhesives, hot-melt adhesives, and active energy ray-curable adhesives can be used. Among these, an active energy ray-curable adhesive is preferable because the thickness of the adhesive layer can be reduced and the adhesive durability under high-temperature and high-humidity conditions is high.
The active energy ray-curable adhesive is an adhesive that can undergo radical polymerization, cationic polymerization, or anionic polymerization by irradiation with an active energy ray such as an electron beam or ultraviolet ray. Among these, photo radical polymerizable adhesives that initiate radical polymerization by irradiation with active light are preferred in that curing can be performed at low energy and the thickness of the adhesive layer can be reduced.
(polymerizable Components)
Examples of the monomer of the radical polymerizable adhesive include a compound having a (meth) acryloyl group and a compound having a vinyl group. Among them, compounds having a (meth) acryloyl group are preferable. Examples of the compound having a (meth) acryloyl group include a (meth) acryloyl groupRadical) acrylic acid C1-20Alkyl (meth) acrylates such as chain alkyl esters, alicyclic alkyl (meth) acrylates, and polycyclic alkyl (meth) acrylates; a hydroxyl group-containing (meth) acrylate; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate, and the like. The radical polymerizable adhesive preferably contains a (meth) acrylamide derivative such as hydroxyethyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, or (meth) acryloylmorpholine, from the viewpoint of improving the adhesion to the easy-to-bond layer and improving the curing rate.
The radical polymerizable adhesive may contain a polyfunctional monomer in addition to the monofunctional monomer as a monomer component. The adhesive composition contains a polyfunctional monomer, and thus tends to have an improved adhesive strength because a crosslinked structure is formed in the cured adhesive layer. Examples of the polyfunctional monomer include esters of (meth) acrylic acid and a polyol such as tripropylene glycol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, cyclic trimethylolpropane formaldehyde (meth) acrylate, dioxane glycol di (meth) acrylate, and EO-modified diglycerol tetra (meth) acrylate.
When the monofunctional monomer and the polyfunctional monomer are used in combination, the amount of the polyfunctional monomer is preferably about 3 to 75 parts by weight, more preferably 5 to 50 parts by weight, and still more preferably 10 to 30 parts by weight, based on 100 parts by weight of the total polymerizable monomers. When the amount of the polyfunctional monomer is within the above range, an adhesive layer having both high adhesive strength and flexibility can be easily formed.
By increasing the amount of the monomer having high compatibility with the easy-adhesion layer as a component of the adhesive, the following tendency is exhibited: an adhesive interface layer in which the binder resin (e.g., urethane) of the easy-adhesive layer 15 and the adhesive exist in a compatible manner is easily formed at the interface between the easy-adhesive layer 15 and the adhesive layer 6. For example, when the binder resin of the easy adhesion layer is a urethane resin, by using a monomer having a Solubility Parameter (SP) of 20 or more (preferably 21 to 24) as a polymerizable monomer constituting the adhesive, the adhesive layer 6 and the easy adhesion layer 15 having a binder resin component such as urethane are compatible with each other, and thus an adhesive interface layer is easily formed at the interface between the easy adhesion film and the adhesive layer. The polymerizable monomer having high compatibility with the easy-adhesive layer may be a monofunctional monomer or a polyfunctional monomer.
When the binder resin of the easy adhesion layer is a urethane resin, the amount of the monomer having an SP of 20 or more is preferably 30 parts by weight or more, more preferably 40 parts by weight or more, further preferably 50 parts by weight or more, and particularly preferably 60 parts by weight or more, based on 100 parts by weight of the total of the polymerizable monomers, from the viewpoint of promoting formation of the adhesion interface layer. The amount of the monomer having an SP within the range of 21 to 24 is preferably 20 parts by weight or more, more preferably 30 parts by weight or more, and still more preferably 40 parts by weight or more. Examples of the polymerizable monomer having an SP within the range of 21 to 24 include acryloylmorpholine (SP: 22.9), N-methoxymethylacrylamide (SP: 22.9), N-ethoxymethylacrylamide (SP: 22.3), and the like.
< photopolymerization initiator >
The photocurable adhesive such as a radical photopolymerizable adhesive preferably contains a photopolymerization initiator. The photopolymerization initiator may be appropriately selected depending on the kind of reaction. Examples of the photopolymerization initiator in the radical polymerizable adhesive include a photoradical generator which is cleaved by light irradiation to generate radicals, and a hydrogen abstraction-type polymerization initiator which is generated by hydrogen abstraction from other molecules by light irradiation. The photo radical generator and the hydrogen abstraction polymerization initiator may also be used in combination. The content of the photopolymerization initiator is usually about 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the monomer. When a radical polymerizable adhesive is used as the electron beam curing type, a photopolymerization initiator is not particularly necessary.
A photosensitizer typified by a carbonyl compound may be added to the radical polymerizable adhesive as needed. The photosensitizer is used to improve the curing speed and sensitivity by electron beams. The amount of the photosensitizer used is usually about 0.001 to 10 parts by weight, preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the monomer.
< other ingredients >
The adhesive composition may contain a resin component such as a polymer or an oligomer in addition to the monomer and the photopolymerization initiator. The adhesive composition can reduce the curing shrinkage when curing the adhesive by containing a polymer or an oligomer. From the viewpoint of suppressing the decrease in curing speed and reducing curing shrinkage, the content of the polymer or oligomer is preferably 5 to 30 parts by weight, more preferably 10 to 25 parts by weight, based on 100 parts by weight of the monomer.
The polymer or oligomer added to the adhesive composition is preferably low in viscosity in consideration of workability in applying the adhesive and uniformity of film thickness. From the viewpoint of suppressing an increase in viscosity of the adhesive composition and reducing curing shrinkage, an oligomer having a weight average molecular weight of about 500 to 15000 is preferable. The molecular weight of the oligomer is more preferably 1000 to 10000, and still more preferably 1500 to 5000. From the viewpoint of excellent compatibility with the above-mentioned monomer and its cured product, an acrylic oligomer is preferable as the oligomer.
The adhesive may contain appropriate additives as needed. Examples of the additives include silane coupling agents, coupling agents such as titanium coupling agents, adhesion promoters such as ethylene oxide, ultraviolet absorbers, deterioration inhibitors, dyes, processing aids, ion traps, antioxidants, tackifiers, fillers, plasticizers, leveling agents, foaming inhibitors, antistatic agents, heat stabilizers, and hydrolysis stabilizers.
[ production of polarizing plate ]
The easy-adhesion film 1 is bonded to one surface (first main surface) of the polarizer 5 via an adhesive layer 6, thereby producing a polarizing plate. As shown in fig. 2, by bonding the polarizer 5 to the surface of the easy-adhesive layer 15 of the easy-adhesive film 1 via the adhesive layer 6, a polarizing plate having high adhesiveness between the polarizer and the polarizer protective film (the easy-adhesive film 1), and excellent mechanical strength and durability can be obtained.
< bonding of adhesive-based polarizer and easily adhesive film >
In the bonding of the polarizer 5 and the easy-adhesive film 1, it is preferable that: after applying an adhesive composition to either or both of the polarizer 5 and the easy-adhesion film 1, the polarizer 5 and the easy-adhesion film 1 are bonded to each other by a roll laminator or the like, and the adhesive is cured. Examples of the method of applying the adhesive composition to the polarizer 5 and/or the easy-adhesion film 1 include a roll method, a spray method, and a dipping method. Before the adhesive composition is applied to the surface of the polarizer 5 and/or the easy-adhesion film 1, a surface treatment such as corona treatment, plasma treatment, or saponification treatment may be performed.
After the polarizer 5 and the easy-adhesion film 1 are bonded, the adhesive is cured depending on the type of the adhesive, thereby forming the adhesive layer 6. In the case of using an active energy ray-curable adhesive, the adhesive is cured by irradiation with an active energy ray such as an electron beam or ultraviolet ray.
After the adhesive is cured, as shown in the enlarged view of fig. 2, an adhesive interface layer 61 is preferably formed at the interface between the easy-adhesion layer 15 and the adhesive layer 6. The adhesive interface layer 61 is a region (compatible layer) where the binder resin component of the easy-adhesive layer 15 and the resin component of the adhesive layer 6 (cured product of the adhesive composition) are compatible with each other (see fig. 6), and the adhesion between the polarizer 5 and the easy-adhesive film 1 tends to be improved by forming the compatible layer at the adhesive interface.
By forming the adhesive interface layer, the adhesiveness is improved, and the cutting workability of the polarizing plate tends to be improved. In general, when a polarizing plate is stretched at a high stretch ratio and cut to a size suitable for the screen size of a display device, microcracks are likely to occur in cut end faces perpendicular to the stretching direction (absorption axis direction). When the adhesive interface layer is formed at the interface between the easy-adhesive layer and the adhesive layer, the generation of micro-cracks during dicing tends to be suppressed, and this contributes to the improvement of the productivity and the improvement of the yield of the polarizing plate.
It is considered that the monomer component of the adhesive composition functions as a solvent to dissolve or swell the resin in the surface layer of the easy-adhesion layer, and the resin component of the easy-adhesion layer permeates into the adhesive composition to form an adhesive interface layer. If the adhesive composition contains a large amount of monomer components that dissolve or swell the binder resin of the easy-adhesion layer, permeation of the resin component of the easy-adhesion layer into the adhesive composition is promoted, and the adhesive interface layer is easily formed.
The temperature at the time of application of the adhesive and/or at the time of bonding the easy-to-bond film to the polarizer also becomes a factor affecting the formation of the adhesive interface layer. Since the permeation rate of the resin component increases as the temperature increases, the compatibility of the resin components of the adhesive layer and the adhesive layer is promoted, and the thickness of the adhesive interface layer tends to increase.
The bonding temperature for forming the adhesive interface layer 61 at the interface between the easy-adhesion layer 15 and the adhesive layer 6 varies depending on the composition of the easy-adhesion layer and the adhesive, but is preferably 5 ℃ or higher, and more preferably 10 ℃ or higher. The higher the bonding temperature, the larger the thickness of the adhesive interface layer 61 tends to be.
As the thickness of the adhesive interface layer 61 increases, the thickness of a region of the adhesive layer 6 where the adhesive interface layer 61 is not formed (the adhesive and the easy-to-adhere layer are incompatible, and the adhesive layer 60 alone in which the adhesive exists) tends to decrease. When the thickness of the adhesive layer 60 is too small (or when the adhesive layer is not present), the cutting processability of the polarizing plate may be reduced. From the viewpoint of forming an adhesive interface layer 61 resulting from compatibility of the easy-adhesion layer with the adhesive and leaving the adhesive-independent layer 60, the bonding temperature is preferably 50 ℃ or lower, and more preferably 40 ℃ or lower.
From the viewpoint of improving the adhesiveness at the interface with the easy-adhesion film 1 (polarizer protective film), the thickness of the adhesive interface layer is preferably 40nm or more, and more preferably 50nm or more. The thickness of the adhesive interface layer 61 may be 75nm or more, 100nm or more, 150nm or more, or 200nm or more. The larger the thickness of the adhesive interface layer, the more the adhesiveness tends to be improved, but as the thickness of the adhesive interface layer increases, the thickness of the adhesive layer alone becomes smaller, and the cutting workability may be lowered. The thickness of the adhesive-independent layer 60 is preferably 120nm or more, and more preferably 150nm or more, from the viewpoint of improving the adhesiveness to the interface with the polarizer 5 and ensuring the cutting processability of the polarizing plate.
From the viewpoint of setting the thicknesses of the adhesive-independent layer 60 and the adhesive interface layer 61 within the above ranges, the thickness of the adhesive layer 6 (the total thickness of the adhesive-independent layer 60 and the adhesive interface layer 61) is preferably 300nm or more, more preferably 400nm or more, and still more preferably 500nm or more. From the viewpoint of thinning the polarizing plate and from the viewpoint of setting the thickness ratio of the adhesive interface layer within an appropriate range, the thickness of the adhesive layer 6 is preferably 3 μm or less, more preferably 2.5 μm or less, and still more preferably 2 μm or less.
The thickness of the adhesive interface layer 61 is preferably 5 to 90%, more preferably 10 to 85%, of the total thickness of the adhesive layer 6 (the total thickness of the adhesive-independent layer 60 and the adhesive interface layer 61). The thickness of the adhesive interface layer 61 may be 15% or more, 20% or more, or 80% or less, or 75% or less, based on the total thickness of the adhesive layer 6. The presence or absence of the adhesive interface layer and the thicknesses of the adhesive interface layer and the adhesive independent layer were determined by Transmission Electron Microscope (TEM) observation of the cross section of the polarizing plate.
Even when the adhesive interface layer 61 is present at the interface of the easy-adhesive layer 15 on the adhesive layer 6 side, a substrate interface layer in which the resin component of the film substrate and the constituent component of the easy-adhesive layer are mixed may be formed at the interface of the easy-adhesive layer 15 on the film substrate 11 side. By forming the interface layer on both the adhesive layer 6 side and the film base material 11 side of the easy-adhesive layer 15, the base material film is firmly adhered to the polarizer, and delamination does not easily occur even in a high-temperature and high-humidity environment or the like.
< transparent protective film >
The transparent protective film 2 may be bonded to the second main surface of the polarizer 5 via an adhesive layer 7. As the transparent protective film 2, any suitable transparent film can be used. The thickness of the transparent protective film 2 is about 5 to 200 μm. The thickness of the transparent protective film 2 is preferably 10 to 100 μm, and more preferably 15 to 60 μm from the viewpoint of mechanical strength, transparency, handleability, and the like. The thickness of the easy-adhesion film 1 and the transparent protective film 2 may be the same or different.
Examples of the material for forming the transparent protective film 2 include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); cellulose polymers such as cellulose diacetate and cellulose triacetate; styrene polymers such as polystyrene and acrylonitrile-styrene copolymer; cyclic polyolefins such as polynorbornene; polycarbonates, and the like.
The transparent protective film 2 may have an easy-adhesion layer (not shown) on the surface to be bonded to the polarizer 5. The transparent protective film 2 may be provided with an easy-adhesion layer similar to the easy-adhesion layer 15 of the easy-adhesion film 1.
As the adhesive layer 7 for bonding the polarizer 5 and the transparent protective film 2, various types of adhesives such as an aqueous adhesive, a solvent adhesive, a hot-melt adhesive, and a radical polymerization curing adhesive can be used. The same adhesive composition can be used for the adhesive layer 6 and the adhesive layer 7.
[ use of polarizing plate ]
The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer can be selected from those based on acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based polymers, rubber-based polymers, and the like.
The polarizing plate may be provided with an adhesive layer in an appropriate manner. Examples thereof include: a method of preparing an adhesive solution having a solid content concentration of about 10 to 40 wt% in which a base polymer or the like is dissolved or dispersed in a solvent such as toluene or ethyl acetate, and attaching the adhesive solution to a polarizing plate; or a method of transferring an adhesive layer formed on an appropriate substrate to a polarizing plate.
An adhesive layer may be provided on both sides of the polarizing plate. When the adhesive layers are provided on both surfaces of the polarizing plate, the composition and thickness of the adhesive layers on the front and back surfaces may be the same or different. The thickness of the adhesive layer is generally about 5 to 500 μm.
On the surface of the adhesive layer, a separator may be temporarily affixed for the purpose of preventing contamination of the adhesive layer and the like. As the separator, a separator obtained by coating the surface of the plastic film with a release agent such as a silicone release agent, a long-chain alkyl release agent, or a fluorine release agent is preferably used.
The polarizing plate may be a laminated polarizing plate in which other optical layers are laminated. Examples of the optical layer include a retardation plate, a viewing angle compensating film, and a brightness enhancing film.
The organic E L display device is formed by attaching a circular polarizing plate in which the polarizing plate of the present invention and a retardation film (typically, a 1/4 wavelength plate) are combined to the surface of the organic E L cell, whereby re-emission of reflected light of external light due to a metal electrode or the like can be reduced and visibility can be improved.
Examples
The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. The "%" described below refers to% by weight unless otherwise specified.
[ production of polarizing element ]
< polarizing plate 1>
While a long roll of a polyvinyl alcohol (PVA) resin film (PE 4500, manufactured by L td.) having a thickness of 45 μm was uniaxially stretched in the longitudinal direction by a roll stretcher so that the longitudinal direction became 5.9 times, a polarizer having a thickness of 18 μm was produced by transporting the long roll in the order of the swelling bath, the dyeing bath, the crosslinking bath 1, the crosslinking bath 2, and the washing bath shown in table 1 and drying the long roll at 70 ℃ for 5 minutes, and the iodine concentration and the potassium iodide concentration in the dyeing bath were adjusted so that the single-sheet transmittance of the polarizer became 43.4%.
[ Table 1]
Composition of aqueous solution Temperature (. degree.C.) Draw ratio
Swelling bath Pure water 20 2.2
Dyeing bath Iodine and potassium iodide are 1: 7 (weight ratio) 30 1.4
Cross-linking bath 1 5.0% boric acid, 3.0% potassium iodide 40 1.2
Cross-linking bath 2 4.3% boric acid, 5.0% potassium iodide 65 1.6
Cleaning bath 2.6% Potassium iodide 20 -
< polarizer 2: thin polarizer
One side of an amorphous polyester film (polyethylene terephthalate/ethylene isophthalate; glass transition temperature 75 ℃) having a thickness of 100 μm was subjected to corona treatment, and the corona-treated side was coated with a coating of 9: 1 (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified polyvinyl alcohol (GOHSEFIMER Z200; polymerization degree 1200, acetoacetyl-modified degree 4.6%, saponification degree 99.0 mol% or more) in a weight ratio, and drying the aqueous solution to prepare a laminate having a PVA-based resin layer having a thickness of 11 μm provided on an amorphous polyester film substrate.
The laminate was uniaxially stretched to 2.0 times at the free end in the longitudinal direction by air-assisted stretching in an oven at 120 ℃ and then, while carrying the laminate in a roll, the laminate was immersed in a 4% boric acid aqueous solution at 30 ℃ for 30 seconds and a staining solution (0.2% iodine, 1.0% potassium iodide aqueous solution) at 30 ℃ for 60 seconds in this order. Then, while the laminate was being transported in a roll, the laminate was immersed in a 30 ℃ crosslinking solution (3% potassium iodide, 3% aqueous solution of boric acid) for 30 seconds to be crosslinked, and immersed in a 70 ℃ aqueous solution of 4% boric acid and 5% potassium iodide to be uniaxially stretched at the free ends in the longitudinal direction so that the total stretching ratio became 5.5 times. Thereafter, the laminate was immersed in a 30 ℃ cleaning solution (4% aqueous potassium iodide solution) to obtain a laminate in which a PVA-based polarizing material having a thickness of 5 μm was provided on an amorphous polyester film substrate.
[ production of easily bondable film ]
(preparation of easy-adhesion composition)
An easy-adhesion composition was prepared by mixing 20.6 parts by weight of an aqueous polyurethane (Super Flex 210R, first industrial pharmaceutical company) containing 34% of solid content, 20.2 parts by weight of an oxazoline-containing polymer aqueous solution (eporos WS-700, manufactured by japan catalyst corporation) containing 25% of solid content, 2.8 parts by weight of 1% by weight of aqueous ammonia, 7.5 parts by weight of a 20% aqueous dispersion of colloidal silica having an average primary particle diameter of 35nm (quartron. p L-3, manufactured by hibiscus chemical company), and 63.9 parts by weight of pure water, the easy-adhesion composition containing 15.3 parts by weight of silica particles with respect to 100 parts by weight of solid content and having a concentration of 9.8% in each of the following examples, and an easy-adhesion layer was formed using the easy-adhesion composition.
< easily adhesive film 1>
An easily-bondable film is produced using a film production apparatus provided with a melt-extrusion film-making apparatus, a gravure coater, a tenter-type simultaneous biaxial stretching apparatus, and a winding apparatus. As the acrylic resin, pellets of an imidized MS resin (glass transition temperature: 120 ℃) similar to that used for producing the "transparent protective film 1A" described in example Japanese unexamined patent publication No. 2017-26939 were used. An acrylic resin was melt-extruded from a T-die to form a film having a thickness of 160 μm, the easy-adhesion composition was applied to one surface of the film in a wet thickness of about 9 μm by a gravure coater, and the film was stretched 2-fold in the longitudinal direction (MD) and the width direction (TD) by a simultaneous biaxial stretching tenter in a heating furnace at a temperature of 140 ℃ to obtain an easy-adhesion film having an easy-adhesion layer having a thickness of 30nm on one surface of an acrylic film having a thickness of 40 μm.
< easily adhesive films 2 to 6>
An easy-adhesion film was obtained in the same manner as in the production of the easy-adhesion film 1, except that the application thickness of the easy-adhesion composition was changed. The thickness of the easy adhesion layer (after stretching) is shown in table 2.
< easy-to-adhere films 7 to 11>
The furnace temperature (stretching temperature) during tenter stretching was changed as shown in table 2. An easy-adhesion film was obtained in the same manner as in the production of the easy-adhesion film 1, except that the stretching temperature was changed.
< film 12>
An acrylic film having a thickness of 40 μm without an easy-adhesion layer was obtained without applying an easy-adhesion composition using a gravure coater.
[ preparation of ultraviolet-curable adhesive ]
< adhesive 1>
The following ultraviolet-curable adhesive was prepared: it comprises 17 parts by weight of N-hydroxyethylacrylamide (SP: 29.6), 50 parts by weight of acryloylmorpholine (SP: 22.9), 17 parts by weight of polypropylene glycol (n.apprxeq.3) diacrylate (ARONIX M-220, manufactured by Toyo Seiyu Co., Ltd., SP: 19.0), and 16 parts by weight of an acrylic plasticizer (ARUFON UP-1190, manufactured by Toyo Seiyu Co., Ltd.), as resin components, 0.5 part by weight of 2-methyl-1- (4-methylthiophenyl) -2-morpholino-1-propanone (IRGACURE 907, manufactured by BASF) and 0.2 part by weight of 2, 4-diethylthioxanthone (KAYACURE DETX-S, manufactured by Nippon Chemicals).
< adhesive 2>
The following ultraviolet-curable adhesive was prepared: comprises 17 parts by weight of N-hydroxyethyl acrylamide, 17 parts by weight of acryloyl morpholine, 50 parts by weight of polypropylene glycol (n.apprxl 3) diacrylate (ARONIXM-220, manufactured by Toyo Seiyu Co., Ltd.), and 16 parts by weight of an acrylic plasticizer (ARUFON UP-1190, manufactured by Toyo Seiyu Co., Ltd.), as resin components, 0.5 part by weight of 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone (IRGACURE 907, manufactured by BASF) and 0.2 part by weight of 2, 4-diethylthioxanthone (KAYACURE DETX-S, manufactured by Nippon chemical Co., Ltd.).
< adhesive 3>
The following ultraviolet-curable adhesive was prepared: it comprises 40 parts by weight of N-hydroxyethyl acrylamide and 60 parts by weight of acryloyl morpholine as a curable component, and further comprises 3 parts by weight of 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone ("Irgacure 907" manufactured by BASF Corporation) as a polymerization initiator.
[ production of polarizing plate 1]
The easy-adhesion films 1 to 11 and the film 12 were used as the polarizer protective film on one surface, and a biaxially stretched cyclic polyolefin (COP) film ("ZEONORFilm ZF-14" manufactured by Zeon corporation) was used as the polarizer protective film on the other surface. On the easy-adhesion layer forming surface of the easy-adhesion Film and the surface of the ZEONOR FilmThe adhesive 3 was applied to a thickness of 1 μm, and the resultant was bonded to a polarizer 1 by a roll laminator, and then the cumulative light amount was irradiated to each of both surfaces of the polarizer at 500/mJ/cm2The adhesive was cured by ultraviolet rays to obtain a polarizing plate having an acrylic Film (easy adhesive Film) bonded to one surface of the polarizer and a ZEONOR Film bonded to the other surface.
[ evaluation ]
< amount of alkali remaining in easily bondable layer >
The amounts of triethylamine and ammonia remaining in the easy-adhesion layer were quantified. The residual amount of triethylamine was quantified by the following method: the powder obtained by scraping the easy-adhesion layer from the surface of the easy-adhesion film was weighed, dissolved in methanol, and quantified by a gas chromatography-mass spectrometry (GC/MS) method of the solution. The residual amount of ammonia was quantified by the following method: the easily adhesive film was immersed in pure water at 25 ℃ and then heated and extracted in a drier at 120 ℃ for 60 minutes, and the amount of ammonia eluted in water was determined by ion chromatography. The total of the amount of triethylamine and the amount of ammonia was used as the amount of residual base.
< adhesion of easy adhesion layer >
An adhesive tape (No. 31B, manufactured by Nindon electric Co., Ltd.) was pressure-bonded to the easy-adhesion layer-forming surface of the easy-adhesion film at a line pressure of 8kg/m and a pressure-bonding speed of 0.3 m/min, and after the tape was stored at 50 ℃ for 48 hours, the tape was held at its tip and subjected to a 180 DEG peel test at a tensile speed of 30 m/min, and the adhesion of the easy-adhesion layer was determined according to the following criteria.
Good: the easy-adhesion layer is not peeled from the acrylic film, and is peeled at the interface between the adhesive tape and the easy-adhesion layer
× peeling at the interface between the acrylic film and the easy-adhesion layer
< visual evaluation >
The surface of the easy-adhesion film was visually observed to evaluate the presence or absence of local haze (increase in haze) due to aggregation of silica particles and the presence or absence of scratches on the surface on which the non-easy-adhesion layer was formed.
Good: no aggregation of silica particles, good in-plane uniformity, no damage
△ No turbidity due to aggregation of silica particles was observed, but damage of 1 μm or less depth was observed on the non-adhesive layer-forming surface
× it was confirmed that the particles of silica were turbid due to aggregation and the surface on which the non-adhesive layer was formed was damaged
< Presence or absence of interface layer on substrate >
The cross section of the easy adhesion layer was observed with a Transmission Electron Microscope (TEM), and it was confirmed whether or not there was a region (substrate interface layer) where the particles in the easy adhesion layer were embedded in the acrylic film at the interface between the acrylic film and the easy adhesion layer. Fig. 3 shows a TEM observation image of the polarizing plate (with the substrate interface layer) using the easy-adhesion film 4, and fig. 4 shows a TEM observation image of the polarizing plate (without the substrate interface layer) using the easy-adhesion film 8.
< humidification durability of polarizing plate >
The polarizing plate was cut to a size of 320mm × 240mm, and the surface on the side of the cyclic polyolefin film was bonded to glass with an acrylic adhesive having a thickness of 20 μm, and the sample was placed in a constant temperature and humidity cell having a temperature of 60 ℃ and a relative humidity of 90% (condition 1) or a constant temperature and humidity cell having a temperature of 85 ℃ and a relative humidity of 85% (condition 2), and held for 500 hours to carry out a heating/humidifying durability test.
Measurement of polarization degree P before durability test0And a polarization degree P after the durability test, and calculating a change amount Δ P of the polarization degree ═ P-P0L. Further, another polarizing plate was disposed on the polarizing plate after the durability test with crossed prisms, and the presence or absence of streaky unevenness was visually observed, and evaluated by the following criteria.
◎ No streaks were observed in any of the samples after the durability tests of Condition 1 and Condition 2
Good: no streaking was observed in the sample after the endurance test of condition 1, and slight streaking was recognized in the sample after the endurance test of condition 2
△ slight streaking was observed in the samples of both the conditions 1 and 2 after the endurance test
× stripe unevenness was clearly recognized in both of the samples after the endurance tests of condition 1 and condition 2
An observation photograph (taken by using a low-brightness unevenness measuring system I-system co., L td. "eye sca L E-4W") of the polarizing plate using the easy-adhesion film 2 and the polarizing plate using the easy-adhesion film 6 under crossed prisms before and after the durability test (60 ℃ c. 90% Rh 500 hours) is shown in fig. 5.
The conditions for producing the easy-adhesion films 1 to 11 (stretching temperature and thickness of the easy-adhesion layer after stretching), the evaluation results of the easy-adhesion films (visual observation, adhesion, presence of a base material interface layer), and the durability test results of the polarizing plate (presence or absence of stripe unevenness and amount of change Δ P in polarization degree) are shown in table 2.
[ Table 2]
Figure BDA0002524550130000291
In the polarizing plate using the acrylic film (film 12) in which the easy-adhesion layer was not formed, no streaks were observed even after the humidification durability test, the decrease in the polarization degree was small, and good optical characteristics were exhibited. However, the adhesion between the acrylic film and the polarizer was low, and peeling of the acrylic film from the polarizer was observed at the end of the polarizer after the humidification durability test.
The easy-adhesion film 6 having an easy-adhesion layer with a thickness of 350nm had good adhesion between the acrylic film and the easy-adhesion layer, and also had good appearance. However, the polarizing plate using the easy-adhesion film 6 as the polarizer protective film showed a large decrease in polarization degree after the humidification durability test, and significant streaky unevenness was observed. Similarly to the easy-adhesion film 5, the easy-adhesion films 7 to 9 having a stretching temperature (heating temperature at the time of forming the easy-adhesion layer) of 120 ℃ or lower exhibited a large decrease in polarization degree after the humidification durability test, and significant streaky unevenness was observed.
In the easy-adhesion films 2 to 5 in which the easy-adhesion layer of 50nm to 250nm is formed at the stretching temperature of 140 ℃, no cloudiness due to aggregation of fine particles is observed, and a good appearance is exhibited. Although fine scratches were observed on the non-adhesive layer-forming surface of the easy-to-bond film 2, the scratches were of a level that they were buried with an adhesive, a bonding agent, or the like and did not become optical defects when the easy-to-bond film was bonded to another member. In addition, the polarizing plates using the easy adhesion films 2 to 5 have better humidification durability and suppressed occurrence of stripe unevenness than the polarizing plate using the easy adhesion film 6.
The easy-adhesion film 1 having an easy-adhesion layer of 30nm in thickness had good humidification durability, but white turbidity due to aggregation of silica fine particles and damage to the surface on which the non-easy-adhesion layer was formed were observed, resulting in poor appearance. The occurrence of damage is considered to be caused by the decrease in dispersibility, the detachment of the silica fine particles from the surface of the easy-adhesion layer, and the decrease in slidability of the easy-adhesion film.
As is clear from comparison of the polarizing plates using the easy-adhesion films 2 to 5 with the polarizing plates using the easy-adhesion films 1 and 6, the smaller the thickness of the easy-adhesion layer and the smaller the residual alkali component, the more the occurrence of stripe unevenness after the humidification durability test is suppressed, and the more excellent the humidification durability is obtained. On the other hand, it is found that when the thickness of the adhesive layer is too small and the residual alkali component is too small, the dispersibility of the fine particles is lowered, and thus appearance defects and sliding properties are caused.
In the easy-adhesion films 10 and 11 in which the easy-adhesion layer having a thickness of 200nm is formed at a stretching temperature of 160 ℃ or 180 ℃, the easy-adhesion films are excellent in appearance and humidification durability of the polarizing plate, as in the easy-adhesion film 4. On the other hand, in the easy adhesion films 7 to 9 in which the easy adhesion layer having a thickness of 200nm was formed at a stretching temperature of 80 to 120 ℃, the residual alkali amount of the easy adhesion layer was large, and significant stripe unevenness was observed after the humidification durability test of the polarizing plate, similarly to the easy adhesion film 6.
From these results, it is understood that an easy-to-adhere film having excellent humidification durability of a polarizing plate when used as a polarizer protective film can be obtained by reducing the amount of residual alkali in the easy-to-adhere layer within a range in which the dispersibility of the inorganic fine particles is not reduced.
The easy-adhesion films 7 to 9 stretched at a low temperature have inferior adhesion to the easy-adhesion layer compared with other examples. In the easy-adhesion film 43 and the like, a base material interface layer (see fig. 3) in which particles are embedded in the acrylic film is formed at the interface between the acrylic film and the easy-adhesion layer, whereas no base material interface layer is formed in the easy-adhesion films 7 to 9 (see fig. 4). From these results, it is found that by increasing the heating temperature after the application of the easy-adhesion composition, the alkali component in the easy-adhesion composition can be effectively volatilized to reduce the amount of residual alkali, and in addition, the adhesion at the interface between the film base and the easy-adhesion layer can be improved.
[ production of polarizing plate 2]
< example 1>
The above-mentioned easy-adhesion film 3 was used as a polarizer protective film on one surface, and a biaxially stretched COP film ("ZEONOR film zf-14" manufactured by Zeon Corporation) was used as a polarizer protective film on the other surface. The above adhesive 1 was applied to the easy-adhesion layer-forming surface of the easy-adhesion film and the surface of the ZEONORFilm in a thickness of about 1 μm in an atmosphere at a temperature of 5.2 ℃, and was bonded to the polarizer 1 by a roll laminator. Then, at room temperature, the cumulative light quantity was irradiated to each of both surfaces at 500/mJ/cm2The adhesive was cured by the ultraviolet ray of (2) to obtain a polarizing plate having an acrylic Film (easy adhesive Film) laminated on one surface of the polarizer and a ZEONOR Film laminated on the other surface.
< examples 2 to 5 and comparative examples 1 and 2>
A polarizing plate was obtained in the same manner as in example 1, except that the temperature during the lamination was changed to that shown in table 3.
< comparative example 3>
A polarizing plate was obtained in the same manner as in example 1, except that the adhesive 2 was used instead of the adhesive 1 and the bonding temperature was set to 23.0 ℃.
< example 6>
The adhesive 1 was applied to the easy-adhesion layer-forming surface of the easy-adhesion film 3 in an atmosphere at a temperature of 23.5 ℃ to a thickness of about 1 μm, and the easy-adhesion film was bonded to the polarizer-side surface of the laminate of the polarizer 2 by a roll laminator, and then irradiated with a cumulative light amount of 500/mJ/cm from the easy-adhesion film side2Thereby curing the adhesive. Then, the amorphous polyester film substrate was peeled off from the laminate to obtain a laminateA polarizing plate having an acrylic film (easy-to-adhere film) bonded to one surface of an optical element and having no polarizer protective film provided on the other surface.
[ evaluation ]
< observation of adhesive layer Cross section >
The cross section of the easy-adhesion film was observed with a Transmission Electron Microscope (TEM), and the presence or absence of a compatible region (adhesion interface layer) at the interface between the adhesive layer and the easy-adhesion layer was confirmed. The thickness of the adhesive interface layer and the thickness of the region (individual layer) where the adhesive layer is present alone and is not compatible with the easy-adhesion layer were determined from the cross-sectional image.
< adhesion >
A polarizing plate was cut into a size of 200mm in the direction parallel to the stretching direction of a polarizer (absorption axis direction) and 20mm in the orthogonal direction (transmission axis direction), a cut was made between an acrylic transparent protective film and the polarizing plate with a cutter, and the polarizing plate was bonded to a glass plate.A peel test was performed at a peel angle of 90 DEG and a peel speed of 1000 mm/min using a tensile compression tester ("TG-1 kN" manufactured by Minebea Co., L td.) to measure the adhesive strength.A case where the adhesive strength was 1.0N/20mm or more was taken as "good, and a case where the adhesive strength was less than 1.0N/20mm was taken as ×.
< processability >
A hydraulic cutter (OP-23H, manufactured by EYE MACHINERY Co., Ltd.) equipped with a Tomson blade of 150mm × 50mm was used to cut out a sheet having a stroke of 26.4mm into a rectangular shape with the absorption axis direction of the polarizing plate as the long side, and all the end faces of 4 sides of the polarizing plate obtained by the cutting were observed with an optical microscope (MX 61L-F, manufactured by Olympus Corporation), and the one having the longest microcrack length of less than 1mm was regarded as good, and the one having a length of 1mm or more was regarded as ×.
The structures of the polarizing plates of examples and comparative examples (the type of the easy-adhesion film, the thickness of the polarizer, the type of the polarizer protective film laminated on the surface opposite to the easy-adhesion film, and the type of the adhesive), the bonding temperature at the time of bonding, the results of observing the cross section of the adhesive layer (the thickness of the adhesive interface layer and the adhesive agent single layer), and the evaluation results (adhesiveness and processability) of the polarizing plates are shown in table 3.
[ Table 3]
Figure BDA0002524550130000331
In comparative example 3 using the adhesive 2, no adhesive interface layer was formed, and the adhesiveness and the cutting processability between the easy-adhesion film and the polarizer were insufficient. In examples 1 to 6 and comparative examples 1 and 2 using the adhesive 1, an adhesive interface layer 61 as shown in fig. 6 was formed at the interface between the adhesive layer and the easy-adhesive layer. It is presumed that since the adhesive 1 contains a large amount of acryloylmorpholine (SP: 22.9), the urethane resin adhesive of the easy-adhesion layer has high compatibility with the adhesive, and the interface layer is formed by the compatibility.
The following tendency was confirmed in examples 1 to 6 and comparative example 1: the higher the temperature at which the easy-to-bond film and the polarizer are bonded, the greater the thickness of the bonding interface layer, and consequently the smaller the thickness of the individual layer of adhesive. This is presumably because the higher the temperature, the more the compatibility of the adhesive composition with the easy-adhesion layer is promoted.
The polarizing plates of examples 1 to 5 were excellent in both adhesiveness and cutting processability. The polarizing plate of example 6, which used a polarizer having a small thickness and had an easily adhesive film laminated only on one surface of the polarizer, was also excellent in both adhesiveness and cutting processability. In comparative examples 1 and 2, although the adhesiveness was good, the thickness of the adhesive layer alone was small (or no separate layer was confirmed), and the dicing processability was reduced. From these results, it can be seen that: the easy-adhesion layer and the adhesive are compatible with each other so that the adhesive layer alone remains, and when both the adhesive interface layer and the adhesive layer alone are present, a polarizing plate having excellent adhesiveness and excellent cutting processability can be obtained.
Description of the reference numerals
1 easily adhesive film
11 film base material
15 easy adhesive layer
18 interfacial layer of substrate
2 transparent film
5 polarizing element
6. 7 adhesive layer
60 separate layer of adhesive
61 bonding interface layer
100 polarizing plate

Claims (11)

1. A polarizing plate comprising: a polyvinyl alcohol-based polarizer having a first main surface and a second main surface, and an adhesive-prone film bonded to the first main surface of the polarizer via an adhesive layer,
the easy-adhesion film is provided with an easy-adhesion layer on the surface of a transparent film base material, the easy-adhesion layer is adhered to the polarizer,
the easy-bonding layer contains a binder resin and inorganic particles having an average primary particle diameter of 10 to 100nm,
the adhesive layer is a cured layer of an active energy ray-curable adhesive,
an adhesive interface layer in which a resin component of the easy-adhesive layer is compatible with a resin component of the adhesive layer and is present at an interface between the easy-adhesive layer and the adhesive layer,
the thickness of the adhesive interface layer is 40nm or more, and the thickness of the adhesive layer excluding the adhesive interface layer is 120nm or more.
2. The polarizing plate according to claim 1, wherein the thickness of the adhesive interface layer is 5 to 90% of the total thickness of the adhesive layer and the adhesive interface layer.
3. The polarizing plate according to claim 1 or 2, wherein the total thickness of the adhesive layer and the adhesive interface layer is 0.3 to 3 μm.
4. The polarizing plate according to any one of claims 1 to 3, wherein the transparent film substrate is an acrylic film.
5. The polarizing plate according to any one of claims 1 to 4, wherein the content of the inorganic fine particles in the easy-adhesion layer is 8 to 50 wt%.
6. The polarizing plate according to any one of claims 1 to 5, wherein the binder resin of the easy-adhesion layer is a urethane resin.
7. The polarizing plate according to any one of claims 1 to 6, wherein a region in which the inorganic fine particles are embedded in the transparent film substrate is present at an interface between the transparent film substrate and the easy-adhesion layer.
8. The polarizing plate according to any one of claims 1 to 7, wherein the easy-adhesion layer contains 5 to 75ppm of an alkali component.
9. The polarizing plate according to any one of claims 1 to 8, wherein the easy-adhesion layer has a thickness of 40 to 280 nm.
10. A method for manufacturing a polarizing plate according to any one of claims 1 to 9,
wherein a first main surface of a polyvinyl alcohol-based polarizer and an easy-adhesion layer-forming surface of an easy-adhesion film are bonded to each other with an active energy ray-curable adhesive composition,
the adhesive composition is cured by irradiation with actinic light, thereby forming an adhesive layer.
11. An image display device, comprising: an image display unit, and the polarizing plate according to any one of claims 1 to 9.
CN201980006231.4A 2018-07-25 2019-07-17 Polarizing plate, method for producing same, and image display device Pending CN111433025A (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP2018139850 2018-07-25
JP2018-139850 2018-07-25
JP2019-045270 2019-03-12
JP2019045270A JP6644927B1 (en) 2018-07-25 2019-03-12 Polarizing plate, method of manufacturing the same, and image display device
PCT/JP2019/028169 WO2020022164A1 (en) 2018-07-25 2019-07-17 Polarizing plate, method for producing same, and image display device

Publications (1)

Publication Number Publication Date
CN111433025A true CN111433025A (en) 2020-07-17

Family

ID=69412193

Family Applications (3)

Application Number Title Priority Date Filing Date
CN201980006231.4A Pending CN111433025A (en) 2018-07-25 2019-07-17 Polarizing plate, method for producing same, and image display device
CN202110949132.9A Pending CN113759455A (en) 2018-07-25 2019-07-22 Optical film, method for producing same, polarizing plate, and image display device
CN201980006223.XA Active CN111448246B (en) 2018-07-25 2019-07-22 Optical film, method for producing same, polarizing plate, and image display device

Family Applications After (2)

Application Number Title Priority Date Filing Date
CN202110949132.9A Pending CN113759455A (en) 2018-07-25 2019-07-22 Optical film, method for producing same, polarizing plate, and image display device
CN201980006223.XA Active CN111448246B (en) 2018-07-25 2019-07-22 Optical film, method for producing same, polarizing plate, and image display device

Country Status (4)

Country Link
JP (3) JP6644927B1 (en)
KR (3) KR20210037598A (en)
CN (3) CN111433025A (en)
TW (3) TWI763976B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113487965A (en) * 2021-06-22 2021-10-08 武汉华星光电半导体显示技术有限公司 Support member, manufacturing method thereof and display module

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2022080790A (en) 2020-11-18 2022-05-30 日東電工株式会社 Film manufacturing system and film manufacturing method
JP7097939B2 (en) 2020-11-20 2022-07-08 日東電工株式会社 Film roll manufacturing method
JP7249985B2 (en) 2020-11-20 2023-03-31 日東電工株式会社 Film manufacturing method
JP2022086829A (en) 2020-11-30 2022-06-09 日東電工株式会社 Film manufacturing system
JP7407694B2 (en) 2020-12-16 2024-01-04 日東電工株式会社 Film manufacturing method
KR20240004226A (en) * 2021-04-30 2024-01-11 닛토덴코 가부시키가이샤 Laminated Optical Film

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000044841A1 (en) * 1999-01-27 2000-08-03 Toyo Boseki Kabushiki Kaisha Surface-protective film
CN101932959A (en) * 2008-01-31 2010-12-29 日东电工株式会社 Polaroid protective film, polarization plates and image display device
CN102112899A (en) * 2008-07-29 2011-06-29 日东电工株式会社 Polarizer-protecting film, and polarizing plate and image display device each comprising polarizer-protecting film
CN103298897A (en) * 2010-12-24 2013-09-11 日东电工株式会社 Adhesive composition curable with actinic energy ray, polarizer, optical film, and image display device
CN105593719A (en) * 2013-09-30 2016-05-18 Lg化学株式会社 Optical film including functional coating layer and polarizing plate and image display device including same
CN105765423A (en) * 2013-09-30 2016-07-13 Lg化学株式会社 Optical film comprising primer layer containing polyester resin and polarizing plate using same
CN106019420A (en) * 2015-03-27 2016-10-12 日东电工株式会社 Optical laminate

Family Cites Families (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4204170B2 (en) * 2000-03-28 2009-01-07 富士フイルム株式会社 Antiglare antireflection film, polarizing plate and liquid crystal display device
JP2005315317A (en) 2004-04-28 2005-11-10 Mitsuboshi Belting Ltd Polyurethane-made belt
TW200712579A (en) * 2005-08-12 2007-04-01 Dainippon Printing Co Ltd Protective film for polarizing plate and polarizing plate
JP4236273B2 (en) * 2006-03-13 2009-03-11 日東電工株式会社 Adhesive optical film and image display device
JP2007268928A (en) 2006-03-31 2007-10-18 Mitsubishi Paper Mills Ltd Inkjet recording medium
WO2009001629A1 (en) * 2007-06-26 2008-12-31 Konica Minolta Opto, Inc. Clear hard coat film, and antireflection film, polarizing plates and displays, made by using the same
JP5779863B2 (en) * 2009-11-30 2015-09-16 大日本印刷株式会社 Manufacturing method of optical film, optical film, polarizing plate and display
KR20130119926A (en) * 2010-09-30 2013-11-01 다이니폰 인사츠 가부시키가이샤 Optical laminate, polarizing plate and image display device
TWI541534B (en) * 2011-10-17 2016-07-11 Dainippon Printing Co Ltd Optical film, polarizing plate and image display device
JP2014048347A (en) 2012-08-29 2014-03-17 Nippon Shokubai Co Ltd Optical film and use of the same
KR101443845B1 (en) * 2012-09-03 2014-09-23 주식회사 엘지화학 Polarizing plate comprising hard coating film
WO2016048016A1 (en) * 2014-09-22 2016-03-31 주식회사 엘지화학 Optical film having excellent water resistance and solvent resistance, and polarization plate comprising same
JP6424084B2 (en) 2014-12-17 2018-11-14 株式会社クラレ Film and film manufacturing method
JP6583956B2 (en) 2015-03-31 2019-10-02 三菱製紙株式会社 Light control sheet
JP2017003906A (en) * 2015-06-15 2017-01-05 日東電工株式会社 Polarization film with adhesive layer on both sides, and image formation apparatus
KR101951864B1 (en) * 2016-03-14 2019-02-25 주식회사 엘지화학 Anti-reflective film and display device
JP6434437B2 (en) * 2016-03-24 2018-12-05 藤森工業株式会社 Release film with excellent releasability
JPWO2017164045A1 (en) 2016-03-25 2019-01-31 日本ゼオン株式会社 Multilayer film manufacturing method and manufacturing apparatus
CN109689363A (en) 2016-09-23 2019-04-26 日本瑞翁株式会社 Multilayer film, polarizing film and liquid crystal display device
JP6683097B2 (en) 2016-09-30 2020-04-15 日本ゼオン株式会社 Method for producing multilayer film
JP6674371B2 (en) * 2016-12-14 2020-04-01 株式会社トッパンＴｏｍｏｅｇａｗａオプティカルフィルム Optical laminate, polarizing plate and display device
JP2018109660A (en) * 2016-12-28 2018-07-12 住友化学株式会社 Acrylic resin film and manufacturing method therefor
JP6568666B1 (en) * 2019-02-21 2019-08-28 日東電工株式会社 Easy-adhesive film and method for producing the same, polarizing plate, and image display device

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000044841A1 (en) * 1999-01-27 2000-08-03 Toyo Boseki Kabushiki Kaisha Surface-protective film
CN101932959A (en) * 2008-01-31 2010-12-29 日东电工株式会社 Polaroid protective film, polarization plates and image display device
CN102112899A (en) * 2008-07-29 2011-06-29 日东电工株式会社 Polarizer-protecting film, and polarizing plate and image display device each comprising polarizer-protecting film
CN103298897A (en) * 2010-12-24 2013-09-11 日东电工株式会社 Adhesive composition curable with actinic energy ray, polarizer, optical film, and image display device
CN105593719A (en) * 2013-09-30 2016-05-18 Lg化学株式会社 Optical film including functional coating layer and polarizing plate and image display device including same
CN105765423A (en) * 2013-09-30 2016-07-13 Lg化学株式会社 Optical film comprising primer layer containing polyester resin and polarizing plate using same
CN106019420A (en) * 2015-03-27 2016-10-12 日东电工株式会社 Optical laminate

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113487965A (en) * 2021-06-22 2021-10-08 武汉华星光电半导体显示技术有限公司 Support member, manufacturing method thereof and display module

Also Published As

Publication number Publication date
KR102452987B1 (en) 2022-10-12
TW202012979A (en) 2020-04-01
CN113759455A (en) 2021-12-07
JP6644927B1 (en) 2020-02-12
KR20200012754A (en) 2020-02-05
CN111448246A (en) 2020-07-24
KR20210037598A (en) 2021-04-06
TW202007743A (en) 2020-02-16
TWI764018B (en) 2022-05-11
TW202012166A (en) 2020-04-01
JP2020024367A (en) 2020-02-13
TWI763976B (en) 2022-05-11
JP2020023171A (en) 2020-02-13
KR102431158B1 (en) 2022-08-11
CN111448246B (en) 2021-08-31
JP2020023170A (en) 2020-02-13
TWI766174B (en) 2022-06-01
JP7014755B2 (en) 2022-02-01
KR20210039978A (en) 2021-04-12
JP6644932B1 (en) 2020-02-12

Similar Documents

Publication Publication Date Title
CN111448246B (en) Optical film, method for producing same, polarizing plate, and image display device
EP2535748A1 (en) Adhesive polarization plate, image display device and methods for manufacturing adhesive polarization plate and image display device
CN110497672B (en) Easy-to-adhere film, method for producing the same, polarizing plate, and image display device
KR102544911B1 (en) Polarizer and image display device
JP6568666B1 (en) Easy-adhesive film and method for producing the same, polarizing plate, and image display device
JP2023095953A (en) Easily adhesive film
CN113635632B (en) Optical film, method for producing the same, polarizing plate, and image display device
WO2019155791A1 (en) Polarizing plate and image display device
WO2020022164A1 (en) Polarizing plate, method for producing same, and image display device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination