CN117242378A - Polarizing film and image display device - Google Patents

Polarizing film and image display device Download PDF

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Publication number
CN117242378A
CN117242378A CN202280032367.4A CN202280032367A CN117242378A CN 117242378 A CN117242378 A CN 117242378A CN 202280032367 A CN202280032367 A CN 202280032367A CN 117242378 A CN117242378 A CN 117242378A
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China
Prior art keywords
meth
polarizer
film
acrylate
polarizing
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CN202280032367.4A
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Chinese (zh)
Inventor
座间优人
山崎达也
春田裕宗
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Nitto Denko Corp
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Nitto Denko Corp
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    • 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
    • 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
    • B32B7/022—Mechanical 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
    • 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
    • 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
    • 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
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • 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

Abstract

The present invention relates to a polarizing film, wherein a 1 st transparent protective film is laminated on one surface of a polarizer via a 1 st adhesive layer, and a non-polarizing portion is formed on at least a part of the polarizer, wherein when the press-in elastic modulus (25 ℃) of the 1 st adhesive layer is E1 (25) (GPa), the press-in elastic modulus (25 ℃) of the non-polarizing portion is E2 (25) (GPa), and the press-in elastic modulus (25 ℃) of the 1 st transparent protective film is E3 (25) (GPa), the polarizing film satisfies the following formula (1); (E1 (25). Times.E3 (25)) (1/2). Gtoreq.0.2XE2 (25) (1).

Description

Polarizing film and image display device
Technical Field
The present invention relates to a polarizing film in which a 1 st transparent protective film is laminated on at least one surface of a polarizer with a 1 st adhesive interposed therebetween. The polarizing film may be used to form an image display device such as a mobile phone, a car navigation device, a monitor for a computer, or a television, or an image display device such as a mobile phone, a car navigation device, a monitor for a computer, or a television, in the form of an optical film in which the polarizing film is laminated.
Background
Internal electronic components such as a camera are mounted on an image display device such as a mobile phone or a notebook Personal Computer (PC). In recent years, with the rapid spread of smart phones and touch panel type information processing apparatuses, further improvement in camera performance and the like has been desired. In addition, in order to cope with diversification and high functionalization of the shape of the image display device, a polarizing film having a polarizing performance in part is required. In order to cope with these demands, a polarizer having a non-polarizing portion formed by chemical treatment at a predetermined portion has been proposed (for example, patent documents 1 and 2).
Prior art literature
Patent literature
Patent document 1: japanese patent application laid-open No. 2018-017925
Disclosure of Invention
Problems to be solved by the invention
In recent years, polarizing films for use in image display devices such as mobile phones and PCs, particularly mobile phones and image display devices such as PCs having flexible displays, and in-vehicle applications have been used under either low temperature or high temperature conditions, and therefore, it has been demanded that cracks (through cracks) not occur in the entire absorption axis direction of a polarizer due to changes in shrinkage stress of the polarizer even in severe environments in which thermal shocks (for example, thermal shock tests in which temperature conditions of-40 ℃ and 85 ℃ are repeated) are used. In general, since the non-polarizing portion of the polarizer has a lower press-in elastic modulus than other portions (polarizing portions) of the polarizer, a difference between the press-in elastic moduli of the non-polarizing portion and the polarizing portion becomes large in the polarizer, and thus, deformation behavior is likely to be different in the portion of the polarizer particularly at high temperatures. As a result, stress applied near the boundary between the unpolarized portion and the polarized portion increases, and cracks may occur near the boundary.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a polarizing film and an image display device which have a polarizer having a non-polarizing portion and are excellent in crack resistance even in a severe temperature environment.
Means for solving the problems
The above problems can be solved by the following constitution. That is, the present invention relates to a polarizing film (1) in which a 1 st transparent protective film is laminated on one surface of a polarizer via a 1 st adhesive layer, wherein the polarizer has a non-polarizing portion formed on at least a part thereof, and wherein when the press-in elastic modulus (25 ℃) of the 1 st adhesive layer is E1 (25) (GPa), the press-in elastic modulus (25 ℃) of the non-polarizing portion is E2 (25) (GPa), and the press-in elastic modulus (25 ℃) of the 1 st transparent protective film is E3 (25) (GPa), the following formula (1) is satisfied:
(E1(25)×E3(25)) (1/2) ≥0.2×E2(25) (1)
preferably, a polarizing film (2) is formed by laminating a 2 nd transparent protective film on the other surface of the polarizer through a 2 nd adhesive layer in the polarizing film (1), wherein when the press-in hardness (25 ℃) of the 2 nd transparent protective film is H5 (25) (GPa) and the press-in hardness (25 ℃) of the 1 st transparent protective film is H3 (25) (GPa),
H3(25)＞H5(25)。
preferably, the polarizing film (3) is one in which, in the polarizing film (2), the press-in elastic modulus (25 ℃) of the 2 nd transparent protective film is E5 (25) (GPa), and the thickness of the 2 nd transparent protective film is d5 (μm),
E5(25)×d5＜200。
preferably, the polarizing film (4) is one in which, in the polarizing film (2) or (3), the press-in elastic modulus (25 ℃) of the 2 nd adhesive layer is E4 (25) (GPa) and the thickness is d4 (μm),
E4(25)×d4＜10。
Preferably, the polarizing film (5) is one of the polarizing films (1) to (4) wherein, when the press-in elastic modulus (80 ℃) of the 1 st adhesive layer is E1 (80) (GPa),
E1(80)/E1(25)＞0.5。
preferably, a polarizing film (6) is provided, wherein in any one of the polarizing films (1) to (5), when the thickness of an adhesive layer between a portion of the polarizer other than the non-polarizing portion and the 1 st transparent protective film is d1 (μm),
d1＜2。
the present invention also relates to an image display device including any one of polarizing films (1) to (6), wherein the non-polarizing portion of the polarizing film is disposed at a position corresponding to a sensor portion.
ADVANTAGEOUS EFFECTS OF INVENTION
In recent years, polarizing films used in severe temperature environments have many applications, and as described above, it is important to ensure durability of the polarizing film, particularly crack resistance of a polarizing lens provided in the polarizing film, even in severe temperature environments. The polarizing film of the present invention has a polarizer having a non-polarizing portion, but the polarizer is excellent in crack resistance even in a severe temperature environment. The reason why such effects can be obtained can be estimated as follows.
The polarizing film of the present invention is designed to: when the press-in elastic modulus (25 ℃) of the 1 st adhesive layer is E1 (25) (GPa), the press-in elastic modulus (25 ℃) of the unpolarized portion is E2 (25) (GPa), and the press-in elastic modulus (25 ℃) of the 1 st transparent protective film is E3 (25) (GPa), the following formula (1) is satisfied;
(E1(25)×E3(25)) (1/2) ≥0.2×E2(25) (1)。
As a result, even in the case of a polarizing film including a polarizer having a non-polarizing portion, the polarizer has excellent crack resistance in a severe temperature environment.
In the present invention, the above-mentioned effects are obtained because the following relational expression is satisfied
(E1(25)×E3(25)) (1/2) ≥0.2×E2(25) (1)。
With respect to formula (1), the product of the press-in elastic modulus of the 1 st adhesive layer and the press-in elastic modulus of the 1 st transparent protective film averages the press-in elastic modulus, that is, (E1 (25). Times.E3 (25)) (1/2) When the relation between the press-fit elastic modulus of the non-polarizing portion is larger than a predetermined relation, stress applied near the boundary between the non-polarizing portion and the polarizing portion of the polarizer is reduced even in a severe temperature environment. As a result ofThe polarizing film of the present invention is excellent in crack resistance of the polarizer even in a severe temperature environment.
As a result of intensive studies by the present inventors, the present invention has for the first time obtained the following findings: when E1, E2, and E3 satisfy the above-described relational expression, the durability of the polarizing film including the polarizing plate having the non-polarizing portion is improved, and in particular, the crack resistance of the polarizing plate can be improved.
Drawings
Fig. 1 is an example of a schematic cross-sectional view of a polarizing film according to an embodiment of the present invention.
Fig. 2 is a schematic illustration of a sample of the adhesive layer-carrying polarizing film after a thermal shock test.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The ratio of the thickness and the like in the drawings is merely an example, and is not limited thereto.
Fig. 1 shows an example of a schematic cross-sectional view of a polarizing film according to an embodiment of the present invention. The polarizing film 10 of this embodiment is formed by laminating a 1 st transparent protective film 3 on one surface of a polarizer 2 via a 1 st adhesive layer 1.
A non-polarizing portion 2A is formed in at least a part of the polarizer 2. The method for forming the non-polarized portion of the polarizer will be described later. In the case where the polarizer is formed with a non-polarized portion, the processing surface of the non-polarized portion is more likely to be recessed in structure than other portions (polarized portions) of the polarizer due to the processing method thereof. The embodiment shown in fig. 1 shows an example in which the concave portion 2h is formed in the processing surface of the polarizer 2. Although the embodiment shown in fig. 1 shows an example in which the concave portion 2h is provided only on the processing surface (upper side in the drawing) and there is no concave portion on the lower side in the drawing, there are cases in which the polarizing mirror surface on the opposite side to the concave portion 2h is somewhat concave depending on the method and conditions for forming the non-polarizing portion. In this case, in the present invention, a portion having a large recess depth (typically, a recess on one surface side to be processed for forming a non-polarizing portion in a polarizer) is used as the recess 2h.
The polarizing film 10 shown in fig. 1 is designed to: when the press-in elastic modulus (25 ℃) of the 1 st adhesive layer 1 is E1 (25) (GPa), the press-in elastic modulus (25 ℃) of the unpolarized section 2A is E2 (25) (GPa), and the press-in elastic modulus (25 ℃) of the 1 st transparent protective film 3 is E3 (25) (GPa), the following formula (1) is satisfied:
(E1(25)×E3(25)) (1/2) ≥0.2×E2(25) (1)。
therefore, even the polarizing film 10 including the polarizer 2 having the non-polarizing portion 2A is excellent in crack resistance of the polarizer 2 in a severe temperature environment. The measurement methods of the press-in elastic moduli E1 (25), E2 (25) and E3 (25) measured at 25 ℃ will be described later. In the present invention, "measurement at 25 ℃ allows measurement in a range of 25±1℃.
In the present invention, in order to further improve the crack resistance of the polarizer in a severe temperature environment, the following formula (1A) is preferably satisfied:
(E1(25)×E3(25)) (1/2) ≥0.3×E2(25)(1A)，
it is further preferable that the following formula (1B) is satisfied:
(E1(25)×E3(25)) (1/2) ≥0.4×E2(25)(1B)。
the polarizing film 10 shown in fig. 1 is designed to: when the 2 nd transparent protective film 5 is laminated on the other surface of the polarizer 2 via the 2 nd adhesive layer 4, the following formula (2) is satisfied when the press-in hardness (25 ℃) of the 2 nd transparent protective film 5 is H5 (25) (GPa) and the press-in hardness (25 ℃) of the 1 st transparent protective film 3 is H3 (25) (GPa):
H3(25)＞H5(25) (2)。
In the image display device, when the polarizing film 10 is disposed so that the 1 st transparent protective film 3 side is the visible side, even when an article having a sharp tip such as a touch pen is touched, the impact transmitted to the polarizer 2 can be reduced, and the stress applied near the boundary between the non-polarizing portion 2A and the polarizing portion of the polarizer 2 can be kept at a small level. In particular, when the non-polarizing portion 2A has the concave portion 2h, a height difference occurs in the surface of the polarizer 2 due to the concave portion 2h, and therefore, cracks are also likely to occur in the polarizer 2 physically, but since the 1 st transparent protective film 3 having a large press-in hardness is disposed on the concave portion 2h side, dimensional changes in the vicinity of the concave portion 2h of the polarizer 2 can be suppressed. As a result, the polarizing film 10 has excellent crack resistance of the polarizer even in a severe temperature environment. The method for measuring the press-in hardness H3 (25) and H5 (25) measured at 25 ℃ will be described later.
In the polarizing film 10 shown in fig. 1, the following formula (3) is satisfied when the press-in elastic modulus (25 ℃) of the 2 nd transparent protective film 5 is E5 (25) (GPa) and the thickness of the 2 nd transparent protective film 5 is d5 (μm):
E5(25)×d5＜200 (3)，
Even when stress is applied to bend the polarizing film 10, the stress on the polarizer 2 can be relaxed. As a result, the polarizing film 10 has excellent crack resistance of the polarizer even in a severe temperature environment. The method for measuring the indentation elastic modulus E5 (25) and the thickness d5 measured at 25 ℃ will be described later.
In the present invention, in order to further improve the crack resistance of the polarizer in a severe temperature environment, the following formula (3A) is preferably satisfied:
E5(25)×d5＜150(3A)
it is further preferable that the following formula (3B) is satisfied:
E5(25)×d5＜100(3B)。
in the polarizing film 10 shown in fig. 1, when the press-in elastic modulus (25 ℃) of the 2 nd adhesive layer 4 is E4 (25) (GPa) and the thickness is d4 (μm), the following expression (4) is satisfied,
E4(25)×d4＜10 (4)
the 2 nd adhesive layer 4 becomes soft and/or the thickness of the 2 nd adhesive layer 4 becomes thin, so even if the 2 nd transparent protective film 5 thermally expands, the transmission of stress caused by thermal expansion to the polarizer 2 can be suppressed. As a result, the polarizing film 10 is excellent in crack resistance of the polarizer even in a severe temperature environment. The method for measuring the indentation elastic modulus E4 (25) and the thickness d4 measured at 25 ℃ will be described later.
In the present invention, in order to further improve the crack resistance of the polarizer in a severe temperature environment, the following formula (4A) is preferably satisfied:
E4(25)×d4＜9.5(4A)，
more preferably, the following formula (4B) is satisfied:
E4(25)×d4＜9.0(4B)，
it is further preferable that the following formula (4C) is satisfied:
E4(25)×d4＜8.5)(4C)。
in the polarizing film 10 shown in fig. 1, when the press-in elastic modulus of the 1 st adhesive layer 1 measured at 80 ℃ is set to E1 (80) (GPa) and the following expression (5) is satisfied, the relaxation of the orientation of the polarizer 2 in a severe temperature environment is easily suppressed, and the decrease in the polarization characteristics of the polarizer 2 can be suppressed.
E1(80)/E1(25)＞0.5 (5)
In the present invention, in order to further improve the crack resistance of the polarizer in a severe temperature environment, the following formula (5A) is preferably satisfied:
E1(80)/E1(25)＞0.6(5A)，
more preferably, the following formula (5B) is satisfied:
E1(80)/E1(25)＞0.7(5B)，
it is further preferable that the following formula (5C) is satisfied:
E1(80)/E1(25)＞0.8(5C)，
still more preferably, the following formula (5D) is satisfied:
E1(80)/E1(25)＞0.9(5D)。
in the polarizing film 10 shown in fig. 1, d1 < 2 is satisfied when the thickness of the adhesive layer between the portion of the polarizer other than the polarizing portion and the 1 st transparent protective film is d1 (μm), and the crack resistance of the polarizer is also excellent in a severe temperature environment. The method for measuring the depth d1 will be described later.
Hereinafter, each member constituting the polarizing film of the present invention will be described.
[ polarizer ]
The polarizing film includes a polarizer made of a resin film containing a dichroic material, and a non-polarizing portion is formed in the polarizer. Typically, the unpolarized portion is a portion (low concentration portion) of the polarizer where the content of the dichroic substance is lower than that of the portion other than the unpolarized portion. However, the non-polarizing portion in the present invention may be a layer obtained by extracting the dichroic material from the polarizer, or may be another layer containing no dichroic material, but is not limited thereto. According to such a configuration, compared with the case where the through hole is formed mechanically (for example, by mechanically peeling off the through hole by using a graver, plotter, water jet, or the like), quality problems such as cracking, delamination (interlayer peeling), and paste overflow can be avoided.
Examples of the method of introducing the unpolarized portion into the polarizer include a method of forming the unpolarized portion by decoloring by chemical treatment, and a method of forming the unpolarized portion by decomposition of a dichroic substance such as laser light. Among these methods, a method of forming a non-polarized portion by decoloring with a chemical treatment is preferable because the content of the dichroic substance itself in the non-polarized portion can be adjusted to a low level and the transparency of the non-polarized portion can be maintained better than a method of forming a non-polarized portion by decomposition of a dichroic substance with a laser or the like.
In the polarizing film, the number, arrangement, shape, size, and the like of the non-polarizing portions can be appropriately designed. For example, the design may be made according to the position, shape, size, and the like of the camera unit of the mounted image display device. Specifically, the non-polarizing portion may be designed so as not to correspond to a portion of the image display device other than the camera (for example, an image display portion).
The transmittance of the unpolarized portion (for example, the transmittance measured at 23 ℃ with light having a wavelength of 550 nm) is preferably 50% or more, more preferably 60% or more, still more preferably 75% or more, and particularly preferably 90% or more. If the transmittance is such, a desired transparency can be ensured. For example, when the unpolarized section is associated with a camera section of the image display apparatus, adverse effects on the imaging performance of the camera can be prevented.
The polarizer preferably exhibits absorption dichroism in the wavelength range of 380nm to 780 nm. The single transmittance (Ts) of the polarizing portion of the polarizer (a portion of the polarizer other than the polarizing portion) is preferably 39% or more, more preferably 39.5% or more, still more preferably 40% or more, and particularly preferably 40.5% or more. The theoretical upper limit of the transmittance of the monomer was 50%, and the practical upper limit was 46%. The monomer transmittance (Ts) is a Y value obtained by measuring a 2-degree field of view (C light source) of JIS Z8701 and correcting for visibility, and may be measured, for example, using an ultraviolet-visible spectrophotometer (product name: V7100, manufactured by japan spectroscopy). The polarization degree of the polarization portion of the polarizer is preferably 99.8% or more, more preferably 99.9% or more, and still more preferably 99.95% or more.
The thickness of the polarizer (resin film) may be set to any appropriate value. The thickness of the polarizer is typically 0.5 μm to 80 μm. The thickness is preferably 30 μm or less, more preferably 25 μm or less, further preferably 18 μm or less, particularly preferably 12 μm or less, further particularly preferably less than 8 μm. The thickness is preferably 1 μm or more. The thinner the thickness of the resin film to be a polarizer, the shorter the time it takes for the dichroic material to be contained in the resin film to come into contact with an alkaline solution to be described later.
In one embodiment, the thickness of the polarizer is preferably 10 μm or more. When an alkaline solution is brought into contact with a resin film having a thickness of 10 μm or more, wrinkles tend to occur easily in a portion (non-polarized portion) where the alkaline solution is brought into contact, and this tendency becomes remarkable after humidification. Wrinkles generated in the resin film may impair not only the appearance but also the function of the resulting polarizer. The polarizer of the present invention can effectively prevent the occurrence of wrinkles even when the thickness is 10 μm or more. Since the resin film having a thickness of less than 10 μm does not wrinkle, a polarizer having an excellent appearance can be provided.
Examples of the dichroic material include iodine and organic dyes, and two or more of them may be used singly or in combination, and iodine is preferably used. This is because the unpolarized portion can be formed well by contact with an alkaline solution described later.
The content of the dichroic material in the non-polarizing portion is preferably 1.0 wt% or less, more preferably 0.5 wt% or less, and still more preferably 0.2 wt% or less. If the content of the dichroic material in the unpolarized portion is within such a range, the desired transparency can be sufficiently imparted to the unpolarized portion. Therefore, for example, when the unpolarized section is associated with the camera section of the image display apparatus, it is possible to realize extremely excellent imaging performance from the viewpoints of both brightness and color tone. On the other hand, the lower limit value of the content of the dichroic material in the non-polarizing portion is usually equal to or less than the detection limit value. In the case of using iodine as the dichroic material, the iodine content can be obtained from, for example, an X-ray intensity measured by fluorescent X-ray analysis and a calibration curve prepared in advance using a standard sample.
The difference between the content of the dichroic material in the other portion and the content of the dichroic material in the non-polarizing portion is preferably 0.5 wt% or more, and more preferably 1 wt% or more.
As a resin for forming the resin film, any suitable resin may be used, and a polyvinyl alcohol resin (hereinafter referred to as "PVA-based resin") is preferably used. Examples of the PVA-based resin include: polyvinyl alcohol, ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be determined in accordance with JIS K6726-1994. By using the PVA-based resin having such a saponification degree, a polarizer excellent in durability can be obtained. If the saponification degree is too high, gelation may occur.
The average degree of polymerization of the PVA-based resin may be appropriately selected depending on the purpose, and is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300. The average polymerization degree can be determined in accordance with JIS K6726-1994.
A polarizer having a non-polarizing portion can be manufactured by bringing a treatment liquid, for example, an alkaline solution, into contact with a resin film containing a dichroic substance. In the case of using iodine as the dichroic substance, the iodine content of the contact portion can be easily reduced by contacting the alkaline solution with a desired portion of the resin film. Specifically, the alkaline solution can penetrate into the resin film by contact. The iodine complex contained in the resin film is reduced by the alkali contained in the alkaline solution to become iodide ions. By reducing the iodine complex to iodide ions, the transmittance of the contact portion can be improved. Further, iodine, which becomes iodide ions, moves from the resin film into the solvent of the alkaline solution. The unpolarized portion thus obtained can maintain its transparency satisfactorily. Specifically, when the transmittance is improved by breaking the iodine complex, the iodine remaining in the resin film is reformed into the iodine complex with the use of the polarizer, and the transmittance is reduced.
Any suitable method may be used as the method of contacting the alkaline solution, and examples thereof include a method of dropping, coating, and spraying the alkaline solution onto the resin film; a method of immersing the resin film in an alkaline solution.
When the alkali solution is contacted, the resin film may be protected with any suitable protecting material so that the alkali solution does not contact a site other than a desired site (the content of the dichroic substance is not made low). Specifically, examples of the protective material for the resin film include a protective film and a surface protective film. The protective film may be used directly as a protective film for the polarizer. The surface protective film is temporarily used when manufacturing the polarizer, and is typically bonded to the resin film via an adhesive layer because the surface protective film is removed from the resin film at any appropriate timing. As other specific examples of the protective material, a photoresist and the like are given.
As the above basic compound, any suitable basic compound can be used. Examples of the basic compound include: alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, inorganic alkali metal salts such as sodium carbonate, organic alkali metal salts such as sodium acetate, ammonia water and the like. Among these, alkali metal and/or alkaline earth metal hydroxides are preferably used, and sodium hydroxide, potassium hydroxide and lithium hydroxide are more preferably used. This is because they can ionize a dichroic substance with good efficiency, and thus can form a non-polarized portion more simply. These basic compounds may be used alone or in combination of two or more.
As the solvent of the alkaline solution, any suitable solvent may be used, and specific examples thereof include: alcohols such as water, ethanol and methanol, diethyl ether, benzene, chloroform and a mixed solvent thereof. Among these, water and alcohol are preferable in that the ionized dichroic material can be satisfactorily moved to the solvent.
The concentration of the alkaline solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, and more preferably 0.1N to 2.5N. If the concentration is in such a range, a desired unpolarized portion can be formed well.
The liquid temperature of the alkaline solution is, for example, 20℃to 50 ℃. The contact time of the alkaline solution is set, for example, according to the thickness of the resin film, the kind and concentration of the alkaline compound contained in the alkaline solution. The contact time is, for example, 5 seconds to 30 minutes, preferably 5 seconds to 5 minutes.
In one embodiment, the resin film surface is covered with the surface protective film such that at least a part of the resin film surface is exposed when the resin film surface is contacted with an alkaline solution. For example, the surface protective film having small circular through holes formed therein can be formed by attaching the surface protective film to a polarizer (resin film) and bringing an alkaline solution into contact with the polarizer. In this case, the other side of the resin film (the side where the surface protective film is not disposed) is preferably also protected.
The resin film may be elongated. When the resin film is long, it is preferable that the resin film and the protective material are stacked in a roll-to-roll manner. Here, "roll-to-roll" refers to stacking films in a roll form while conveying the films in a roll form, with the films aligned in the longitudinal direction. The elongated surface protective film has through holes formed at predetermined intervals along its longitudinal direction and/or width direction, for example. The production method of a polarizer using the above-mentioned long resin film and the surface protective film used for producing the long resin film are described in Japanese patent application laid-open No. 2016-027135, japanese patent application laid-open No. 2016-027136, japanese patent application laid-open No. 2016-027137, japanese patent application laid-open No. 2016-027138, and Japanese patent application laid-open No. 2016-027139, and these descriptions are incorporated by reference.
When the alkaline solution is brought into contact, the resin film is preferably made into a state that can be used as a polarizer. Specifically, it is preferable to perform various treatments such as swelling treatment, stretching treatment, dyeing treatment using the above-mentioned dichroic substance, crosslinking treatment, washing treatment, drying treatment, and the like. In the case of performing various treatments, the resin film may be a resin layer formed on the substrate. The laminate of the substrate and the resin layer can be obtained, for example, by a method of applying a coating liquid containing the above-described resin film-forming material to the substrate, a method of laminating a resin film on the substrate, or the like.
The dyeing treatment is typically performed by adsorbing a dichroic substance. Examples of the adsorption method include: a method of immersing the resin film in a dyeing liquid containing a dichroic substance, a method of coating the dyeing liquid on the resin film, a method of spraying the dyeing liquid onto the resin film, or the like is preferable because the dichroic substance can be adsorbed well.
When iodine is used as the dichroic material, an aqueous iodine solution is preferably used as the dyeing liquid. The amount of iodine to be blended is preferably 0.04 to 5.0 parts by weight based on 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add iodide to the aqueous iodine solution. As iodide, potassium iodide is preferably used. The amount of iodide to be blended is preferably 0.3 to 15 parts by weight based on 100 parts by weight of water.
In the stretching treatment described above, the resin film is typically uniaxially stretched to 3 to 7 times. The stretching direction may correspond to the absorption axis direction of the obtained polarizer.
In the case of forming the unpolarized portion of the polarizer by decoloring with a chemical treatment, the contact surface (unpolarized portion) of the alkaline solution is recessed as compared with other polarized portions, thereby forming a concave portion in the unpolarized portion. The maximum depth dh of the concave portion is preferably changed depending on the thickness of the polarizer and the contact condition (temperature/time, etc.) with the alkaline solution, since it is easy to improve visibility of the polarizing film at high temperature and high humidity when the depth is 0.1 to 2.0 (μm), particularly 0.1 to 1.0 (μm).
In the present invention, any appropriate process may be further included as needed in manufacturing the polarizer to be used. Examples thereof include a step of reducing alkali metal and/or alkaline earth metal, a step of removing the alkaline solution, and the like. These steps may be performed at any appropriate stage of the above-described production method.
By bringing the alkaline solution into contact with the resin film, an alkali metal hydroxide and/or an alkaline earth metal hydroxide can remain in the contact portion. In addition, by bringing the alkaline solution into contact with the resin film, metal salts of alkali metal and/or alkaline earth metal can be formed at the contact portion, and these can generate hydroxide ions, and the generated hydroxide ions act (decompose/reduce) with a dichroic substance (for example, an iodine complex) present around the contact portion, thereby expanding a non-polarized region (low concentration region). Therefore, by reducing the alkali metal and/or alkaline earth metal, the non-polarized region can be suppressed from expanding with time, and the desired non-polarized portion shape can be maintained. Details of the step of reducing the alkali metal and/or alkaline earth metal are described in, for example, japanese patent application laid-open No. 2015-215609, japanese patent application laid-open No. 2015-215610 and Japanese patent application laid-open No. 2015-215611, and these descriptions are incorporated herein by reference.
Specific examples of the method for removing the alkaline solution and/or the post-crosslinking solution include washing, wiping with a rag or the like, suction removal, natural drying, heat drying, air-blow drying, and drying under reduced pressure. Examples of the cleaning liquid used for cleaning include water (pure water), alcohols such as methanol and ethanol, and a mixture thereof, and water is preferably used. The number of times of washing is not particularly limited, and may be multiple times. In the case of removal by drying, the drying temperature is, for example, 20℃to 100 ℃.
[ transparent protective film ]
The polarizing film of the present invention is formed by laminating a transparent protective film on at least one surface of a polarizer via an adhesive. In the polarizing film of the present invention, for example, the same or different transparent protective film may be further provided on a surface of the polarizer opposite to the surface on which the transparent protective film is laminated via an adhesive layer.
As a material constituting the 1 st transparent protective film and/or the 2 nd transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like can be used. Specific examples of such thermoplastic resins include cellulose resins such as cellulose triacetate, polyester resins, polyether sulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film may contain 1 or more of any appropriate additive. Examples of the additive include: ultraviolet light absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the transparent protective film is 50 wt% or less, there is a concern that the thermoplastic resin may not exhibit sufficiently high transparency or the like inherent in the thermoplastic resin.
The material for forming the transparent protective film is preferably a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like, and particularly preferably has a moisture permeability of 150g/m 2 Preferably less than/24 h, particularly preferably 140g/m 2 Preferably less than 24 hours, more preferably 120g/m 2 And/or 24h or less.
The transparent protective film may be provided with a functional layer such as a hard coat layer, an antireflection layer, an anti-blocking layer, a diffusion layer, or an antiglare layer on one surface thereof which is not bonded to the polarizer. The functional layers such as the hard coat layer, the antireflection layer, the anti-blocking layer, the diffusion layer, and the antiglare layer may be provided as a layer different from the transparent protective film, in addition to the transparent protective film itself.
The thickness of the transparent protective film can be appropriately determined, and is generally about 1 to 500 μm, preferably 1 to 300 μm, more preferably 5 to 200 μm, still more preferably 10 to 200 μm, still more preferably 20 to 80 μm, from the viewpoints of handling properties such as strength and handling properties, and thin layer properties.
As the transparent protective film, a retardation film having a retardation in the front direction of 40nm or more and/or a retardation in the thickness direction of 80nm or more can be used. The front phase difference is usually controlled to a range of 40 to 200nm, and the thickness direction phase difference is usually controlled to a range of 80 to 300 nm. When a retardation film is used as the transparent protective film, the retardation film also functions as the transparent protective film, and thus can be thinned. In the polarizing film of the present invention, for example, a retardation film may be further provided on a surface of the polarizer opposite to the surface on which the transparent protective film is laminated, with an adhesive layer interposed therebetween.
As the retardation film, there may be mentioned: a birefringent film obtained by subjecting a polymer material to unidirectional or bidirectional stretching treatment, an alignment film of a liquid crystal polymer, and a retardation film obtained by supporting an alignment layer of a liquid crystal polymer with a film. The thickness of the retardation film is not particularly limited, and is generally about 20 to 150. Mu.m.
As the retardation film, a retardation film of inverse wavelength dispersion type satisfying the following formulas (1) to (3) can be used:
0.70＜Re[450]/Re[550]＜0.97···(1)
1.5×10 -3 ＜Δn＜6×10 -3 ···(2)
1.13＜NZ＜1.50···(3)
(wherein Re 450 and Re 550 are in-plane phase difference values of the retardation film measured at 23 ℃ by light having wavelengths of 450nm and 550nm, respectively, deltan is in-plane birefringence which is nx-ny when refractive indexes in the slow axis direction and the fast axis direction of the retardation film are nx and ny, respectively, and NZ is a ratio of nx-NZ to nx-ny when NZ is a refractive index in the thickness direction of the retardation film, wherein nx-NZ is thickness-direction birefringence and nx-ny is in-plane birefringence).
A retardation layer may be provided in the polarizing film of the present invention. The retardation layer may be a single layer or a single layer, or may double as a protective layer for a polarizer. In the polarizing film of the present invention, for example, a retardation layer may be provided on a surface of the polarizer opposite to the surface on which the transparent protective film is laminated, with an adhesive layer interposed therebetween. The kind, number, combination, arrangement position, and characteristics of the retardation layers can be appropriately set according to the purpose.
The retardation layer is preferably formed using a liquid crystalline compound, and a solvent containing the liquid crystalline compound can be applied using, for example, a bar, a gap coater, a comma coater, a gravure coater, a slit die, or the like. In this case, the applied liquid crystal solution may be naturally dried or may be heated and dried. The liquid crystalline solution is preferably applied in a concentration lower than the isotropic phase-liquid crystal phase transition concentration, that is, in an isotropic phase state. In this case, it can be stably oriented by a rubbing treatment, photo-orientation, or the like.
[ adhesive layer ]
The polarizing film of the present invention comprises a 1 st transparent protective film laminated on one surface of a polarizer via a 1 st adhesive layer. A 2 nd transparent protective film may be laminated on the other surface of the polarizer with a 2 nd adhesive interposed therebetween. The thickness of the 1 st adhesive layer (corresponding to d1 in the polarizing film 10 shown in fig. 1) is preferably 2 μm or less, more preferably 1.8 μm or less, and particularly preferably 1.6 μm or less. The thickness of the 2 nd adhesive layer (d 4 in the polarizing film 10 shown in fig. 1) is preferably 2 μm or less, more preferably 1.8 μm or less, and particularly preferably 1.6 μm or less. The lower limit of the thickness of the 1 st adhesive layer and the 2 nd adhesive layer is exemplified by a thickness capable of securing a degree of adhesive force, for example, about 0.5 μm. The 1 st adhesive layer and/or the 2 nd adhesive layer may be formed by, for example, a cured product layer of the curable resin composition.
The invention is characterized by the following design: when the press-in elastic modulus (25 ℃) of the 1 st adhesive layer is E1 (25) (GPa), the press-in elastic modulus (25 ℃) of the non-polarized portion formed on the polarizer is E2 (25) (GPa), and the press-in elastic modulus (25 ℃) of the 1 st transparent protective film is E3 (25) (GPa), the following formula (1) is satisfied:
(E1(25)×E3(25))(1/2)≥0.2×E2(25) (1)。
the material constituting the adhesive layer so as to satisfy the above formula (1) may be only a curable resin composition described later, or an easily adhesive composition may be used in combination with the curable resin composition.
The curable resin composition can be classified into a radical polymerization curable resin composition and a cationic polymerization curable resin composition. In the present invention, active energy rays having a wavelength in the range of 10nm to less than 380nm are denoted by ultraviolet rays, and active energy rays having a wavelength in the range of 380nm to 800nm are denoted by visible rays.
Examples of the monomer component constituting the radical polymerizable curable resin composition include compounds having a radical polymerizable functional group having a carbon-carbon double bond such as a (meth) acryloyl group and a vinyl group. The monomer component may be any monofunctional radical polymerizable compound or polyfunctional radical polymerizable compound having 2 or more polymerizable functional groups. In addition, these radically polymerizable compounds may be used singly or in combination of 1 or more than 2. As these radical polymerizable compounds, for example, compounds having a (meth) acryloyl group are preferable. In the present invention, (meth) acryl means acryl and/or methacryl, and "(meth)" means the same as follows.
Examples of the monofunctional radical polymerizable compound include (meth) acrylamide derivatives having a (meth) acrylamide group. The (meth) acrylamide derivative is preferable in terms of ensuring adhesion to a polarizer and various transparent protective films, and in terms of high polymerization rate and excellent productivity. Specific examples of the (meth) acrylamide derivative include: n-alkyl (meth) acrylamide derivatives such as N-methyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-hexyl (meth) acrylamide; n-hydroxyalkyl (meth) acrylamide derivatives such as N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, and N-methylol-N-propyl (meth) acrylamide; n-aminoalkyl-containing (meth) acrylamide derivatives such as aminomethyl (meth) acrylamide and aminoethyl (meth) acrylamide; n-alkoxy (meth) acrylamide derivatives such as N-methoxymethacrylamide and N-ethoxymethacrylamide; n-mercaptoalkyl (meth) acrylamide derivatives such as mercaptomethyl (meth) acrylamide and mercaptoethyl (meth) acrylamide; etc. Examples of the heterocyclic ring-containing (meth) acrylamide derivative in which a heterocyclic ring is formed on the nitrogen atom of the (meth) acrylamide group include: n-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like.
Among the above (meth) acrylamide derivatives, N-hydroxyalkyl (meth) acrylamide derivatives are preferable in terms of adhesion to a polarizer and various transparent protective films, and examples of monofunctional radical polymerizable compounds include various (meth) acrylic derivatives having a (meth) acryloyloxy group. Specific examples include: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, n-octadecyl (meth) acrylate, and the like (meth) acrylic acid (carbon number 1-20) alkyl esters.
Examples of the (meth) acrylic acid derivative include: cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and cyclopentyl (meth) acrylate; aralkyl (meth) acrylates such as benzyl (meth) acrylate; polycyclic (meth) acrylates such as 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norbornene-2-ylmethyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and dicyclopentanyl (meth) acrylate; alkoxy-or phenoxy-containing (meth) acrylates such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, alkylphenoxypolyethylene glycol (meth) acrylate, and the like; etc.
Further, examples of the (meth) acrylic acid derivative include: hydroxy (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and the like, and hydroxy (meth) acrylates such as 4- (hydroxymethyl) cyclohexyl methyl acrylate, cyclohexanedimethanol mono (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate and glycidyl 4-hydroxybutyl (meth) acrylate; halogen-containing (meth) acrylates such as 2, 2-trifluoroethyl (meth) acrylate, 2-trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, and 3-chloro-2-hydroxypropyl (meth) acrylate; alkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate; oxetanyl (meth) acrylates such as 3-oxetanyl methyl (meth) acrylate, 3-methyloxybutyl methyl (meth) acrylate, 3-ethyloxetanyl methyl (meth) acrylate, 3-butyloxetanyl methyl (meth) acrylate, 3-hexyloxetanyl methyl (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, butyrolactone (meth) acrylate and other (meth) acrylates having a heterocyclic ring, hydroxypivalic acid neopentyl glycol (meth) acrylic acid adducts, p-phenylphenol (meth) acrylates and the like.
Further, examples of the monofunctional radical polymerizable compound include: carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.
Examples of the monofunctional radical polymerizable compound include: lactam vinyl monomers such as N-vinyl pyrrolidone, N-vinyl-epsilon-caprolactam, methyl vinyl pyrrolidone, and the like; vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinylAnd vinyl monomers having nitrogen-containing heterocyclic rings such as oxazole and vinyl morpholine.
Further, as the monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. The radical polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth) acryloyl group at a terminal or in a molecule thereof, and having an active methylene group. Examples of the active methylene group include: acetoacetyl, alkoxymalonyl, or cyanoacetyl groups, and the like. The active methylene group is preferably an acetoacetyl group. Specific examples of the radical polymerizable compound having an active methylene group include: acetoacetoxyethyl (meth) acrylates such as 2-acetoacetoxyethyl (meth) acrylate, 2-acetoacetoxyethyl propyl (meth) acrylate, and 2-acetoacetoxyethyl-1-methylethyl (meth) acrylate; 2-ethoxymalonacyloxyethyl (meth) acrylate, 2-cyanoacetoxyethyl (meth) acrylate, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetoxybutyl) acrylamide, N- (4-acetoacetoxyethylmethylbenzyl) acrylamide, N- (2-acetoacetylamino ethyl) acrylamide, and the like. The radical polymerizable compound having an active methylene group is preferably acetoacetoxyethyl alkyl (meth) acrylate.
Examples of the polyfunctional radical polymerizable compound having 2 or more polymerizable functional groups include: tripropylene glycol di (meth) Acrylate, tetraethylene glycol di (meth) Acrylate, 1, 6-hexanediol di (meth) Acrylate, 1, 9-nonanediol di (meth) Acrylate, 1, 10-decanediol di (meth) Acrylate, 2-ethyl-2-butylpropanediol di (meth) Acrylate, bisphenol A ethylene oxide adduct di (meth) Acrylate, bisphenol A propylene oxide adduct di (meth) Acrylate, bisphenol A diglycidyl ether di (meth) Acrylate, neopentyl glycol di (meth) Acrylate, tricyclodecanedimethanol di (meth) Acrylate, cyclic trimethylolpropane methylal (meth) Acrylate (Cyclic Trimethylolpropane formal (meth) Acrylate), di (meth) AcrylateEsters of (meth) acrylic acid with polyhydric alcohols such as alkylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, EO-modified diglycerol tetra (meth) acrylate, and 9, 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl group ]Fluorene. Specific examples thereof include ARONIX M-220 (manufactured by Toyama Co., ltd.), LIGHT ACRYLATE 1,9ND-A (manufactured by Kyowa Co., ltd.), LIGHT ACRYLATE DGE-4A (manufactured by Kyowa Co., ltd.), LIGHT ACRYLATE DCP-A (manufactured by Kyowa Co., ltd.), SR-531 (manufactured by Sartomer Co., ltd.), CD-536 (manufactured by Sartomer Co., ltd.). Further, as needed, there may be mentioned: various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) propenesAcid esters, various (meth) acrylate monomers, and the like.
In the present invention, the curable resin composition may contain an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer in addition to the radical polymerizable compound. By including the acrylic oligomer in the adhesive composition, the curing shrinkage of the composition when the composition is cured by irradiation with active energy rays can be reduced, and the interface stress between the adhesive layer and an adherend such as a polarizer or an optical film can be reduced. As a result, the adhesive layer and the adherend can be prevented from being reduced in adhesion.
In view of workability and uniformity at the time of application, the curable resin composition is preferably low in viscosity, and therefore the acrylic oligomer obtained by polymerizing the (meth) acrylic monomer is also preferably low in viscosity. The weight average molecular weight (Mw) of the low-viscosity acrylic oligomer capable of preventing curing shrinkage of the adhesive layer is preferably 15000 or less, more preferably 10000 or less, particularly preferably 5000 or less. On the other hand, in order to sufficiently suppress curing shrinkage of the cured product layer (adhesive layer), the weight average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1000 or more, particularly preferably 1500 or more. Specific examples of the (meth) acrylic monomer constituting the acrylic oligomer include: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, n-octadecyl (meth) acrylate and the like (meth) acrylic acid (having 1 to 20 carbon atoms), and, for example: cycloalkyl (meth) acrylates (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, and the like), aralkyl (meth) acrylates (e.g., benzyl (meth) acrylate, and the like), polycyclic (meth) acrylates (e.g., 2-isobornyl (meth) acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornene-2-ylmethyl (meth) acrylate, 3-methyl-2-norbornylmethyl (meth) acrylate, and the like), hydroxy-containing (meth) acrylates (e.g., hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 3-dihydroxypropyl methyl butyl (meth) acrylate, and the like), alkoxy-containing or phenoxy (meth) acrylates (e.g., 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and the like), epoxy-containing (meth) acrylates (e.g., glycidyl (meth) acrylate, and the like), halogen-containing (meth) acrylates (e.g., 2-trifluoroethyl (meth) acrylate, 2-trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.), alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate, etc.), and the like. These (meth) acrylates may be used singly or in combination of 2 or more. Specific examples of the acrylic oligomer (E) include "ARUFON" manufactured by eastern synthetic corporation, "ACTFLOW" manufactured by holly research chemical corporation, and "joncyl" manufactured by BASF Japan ltd.
The blending amount of the acrylic oligomer is usually preferably 15 parts by weight or less relative to 100 parts by weight of the total amount of the monomer components in the curable resin composition. When the content of the acrylic oligomer in the composition is too large, the reaction rate when the composition is irradiated with active energy rays may be drastically reduced, resulting in poor curing. On the other hand, in order to sufficiently suppress curing shrinkage of the adhesive layer, it is preferable that 3 parts by weight or more of the acrylic oligomer is contained in the composition.
The curable resin composition preferably contains a photopolymerization initiator. The photopolymerization initiator may be appropriately selected according to active energy rays. In the case of curing by ultraviolet rays or visible light, a photopolymerization initiator which is cleaved by ultraviolet rays or visible light is used. Examples of the photopolymerization initiator include: benzophenone compounds such as dibenzoyl, benzophenone, benzoyl benzoic acid, and 3,3' -dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α -hydroxy- α, α' -dimethyl acetophenone, 2-methyl-2-hydroxy propiophenone, and α -hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone, and 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropane-1-one; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, anisoin methyl ether, and the like; aromatic ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oximes such as 1-phenyl-1, 1-propanedione-2- (O-ethoxycarbonyl) oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, 2, 4-diisopropylthioxanthone and dodecylthioxanthone; camphorquinone; halogenated ketones; acyl phosphine oxides; acyl phosphonates and the like.
The amount of the photopolymerization initiator is 20 parts by weight or less based on 100 parts by weight of the total amount of the polymerizable compound A. The amount of the photopolymerization initiator is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, and still more preferably 0.1 to 5 parts by weight.
In the case of using the curable resin composition in the form of a visible light curable resin composition, it is particularly preferable to use a photopolymerization initiator having high sensitivity to light of 380nm or more. The photopolymerization initiator having high sensitivity to light of 380nm or more will be described later.
As the photopolymerization initiator, a compound represented by the following general formula (1) is preferably used alone; or a combination of a compound represented by the general formula (1) and a photopolymerization initiator having a high sensitivity to light of 380nm or more, which will be described later.
[ chemical formula 1]
(wherein R is 1 R is R 2 represents-H, -CH 2 CH 3 -iPr or Cl, R 1 R is R 2 May be the same or different). When the compound represented by the general formula (1) is used, the adhesion is superior to the case of using a photopolymerization initiator having a high sensitivity to light of 380nm or more alone. Among the compounds of the general formula (1), R is particularly preferable 1 R is R 2 is-CH 2 CH 3 Diethyl thioxanthone of (a). The composition ratio of the compound represented by the general formula (1) in the curable resin composition is preferably 0.1 to 5% by weight, more preferably 0.5 to 4% by weight, and even more preferably 0.9 to 3% by weight, relative to the total amount of the curable resin composition.
In addition, a polymerization initiator is preferably added as needed. Examples of the polymerization initiator include: triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate and the like, and ethyl 4-dimethylaminobenzoate is particularly preferred. When the polymerization initiator is used, the amount of the polymerization initiator to be added is usually 0 to 5% by weight, preferably 0 to 4% by weight, and most preferably 0 to 3% by weight, based on the total amount of the curable resin composition.
In addition, a known photopolymerization initiator may be used in combination, as required. Since the transparent protective film having UV absorbing ability does not transmit light of 380nm or less, it is preferable to use a photopolymerization initiator having high sensitivity to light of 380nm or more as the photopolymerization initiator. Specific examples include: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholino) phenyl ] -1-butanone, 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, bis (. Eta.5-2, 4-cyclopentadien-1-yl) bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium, and the like.
The curable resin composition preferably contains a silane coupling agent. Specific examples of the silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane and the like, which are active energy ray-curable compounds.
Preferably 2- (3, 4 epoxycyclohexyl) ethyltrimethoxysilane, 3-epoxypropoxypropyl trimethoxysilane, 3-epoxypropoxypropyl methyldiethoxysilane, 3-epoxypropoxypropyl triethoxysilane.
The amount of the silane coupling agent to be blended is preferably in the range of 0.01 to 20% by mass, more preferably 0.05 to 15% by mass, and still more preferably 0.1 to 10% by mass, relative to the total amount of the adhesive composition. This is because the storage stability of the adhesive composition deteriorates when the amount exceeds 20 mass%, and the adhesive water resistance effect cannot be sufficiently exhibited when the amount is less than 0.1 mass%.
Specific examples of the non-active energy ray-curable silane coupling agent other than the above include: 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, imidazole silane, and the like.
The curable resin composition may further contain a compound represented by the following general formula (3) in the adhesive composition, if necessary,
[ chemical formula 2]
(wherein X is a functional group containing a reactive group, R 6 R is R 7 Each independently represents a hydrogen atom, an aliphatic hydrocarbon group optionally having a substituent, an aryl group, or a heterocyclic group),
preferably a compound represented by the following general formula (3'),
[ chemical formula 3]
(wherein Y is an organic group, X' is a reactive group contained in X, R 6 R is R 7 The same meaning as described above),
further preferred are compounds represented by the following general formulae (3 a) to (3 d).
[ chemical formula 4]
When these compounds are blended in the adhesive composition, adhesion to a polarizer or a transparent protective film may be improved, which is preferable. The content of the compound represented by the general formula (3) in the curable water-dispersible composition is preferably 0.001 to 50% by mass, more preferably 0.1 to 30% by mass, and most preferably 1 to 10% by mass, from the viewpoint of improving the adhesion between the polarizer and the transparent protective film and the water resistance.
In the general formula (3), the aliphatic hydrocarbon group may be a linear or branched alkyl group optionally having a substituent of 1 to 20 carbon atoms, a cyclic alkyl group optionally having a substituent of 3 to 20 carbon atoms, or an alkenyl group of 2 to 20 carbon atoms, and the aryl group may be a phenyl group optionally having a substituent of 6 to 20 carbon atoms, a naphthyl group optionally having a substituent of 10 to 20 carbon atoms, or the like, and the heterocyclic group may be a heterocyclic group,examples thereof include a 5-or 6-membered ring group containing at least one hetero atom and optionally having a substituent, and these groups are optionally linked to each other to form a ring. In the general formula (3), R is 6 R is R 7 Preferably a hydrogen atom, a linear or branched alkyl group having 1 to 3 carbon atoms, and most preferably a hydrogen atom.
The compound represented by the general formula (3) has X which is a functional group containing a reactive group and is a functional group capable of reacting with a curable component constituting the adhesive layer, and examples of the reactive group contained in X include: hydroxy, amino, aldehyde, carboxyl, vinyl, (meth) acryl, styryl, (meth) acrylamido, vinyl ether, epoxy, oxetanyl, α, β -unsaturated carbonyl, mercapto, halogen groups, and the like. When the curable resin composition constituting the adhesive layer is active energy ray-curable, the reactive group contained in X is preferably at least 1 reactive group selected from the group consisting of vinyl, (meth) acryl, styryl, (meth) acrylamide, vinyl ether, epoxy, oxetane and mercapto groups, and particularly when the adhesive composition constituting the adhesive layer is free radical-polymerizable, the reactive group contained in X is preferably at least 1 reactive group selected from the group consisting of (meth) acryl, styryl and (meth) acrylamide groups, and when the compound represented by the general formula (1) has a (meth) acrylamide group, the reactivity is high, and the copolymerization ratio with the active energy ray-curable resin composition is improved, and thus is more preferred. Further, the (meth) acrylamide group is highly polar and excellent in adhesion, and is therefore preferable in terms of efficiently obtaining the effect of the present invention. In the case where the curable resin composition constituting the adhesive layer is cationically polymerizable, the reactive group contained in X preferably has at least 1 functional group selected from the group consisting of a hydroxyl group, an amino group, an aldehyde group, a carboxyl group, a vinyl ether group, an epoxy group, an oxetanyl group, and a mercapto group, and particularly in the case where the curable resin layer has an epoxy group, the obtained curable resin layer is excellent in adhesion to an adherend, and in the case where the curable resin composition has a vinyl ether group, the curable resin composition is excellent in curability, and therefore preferred.
In the present invention, the compound represented by the general formula (3) may be a compound in which a reactive group is directly bonded to a boron atom, but as in the above specific example, the compound represented by the general formula (3) is preferably a compound in which a reactive group is bonded to a boron atom via an organic group, that is, a compound represented by the general formula (3'). In the case where the compound represented by the general formula (3) is a compound bonded to a reactive group via an oxygen atom bonded to a boron atom, for example, the adhesion water resistance of the polarizing film tends to be deteriorated. On the other hand, the compound represented by the general formula (3) has no boron-oxygen bond but has a boron-carbon bond by bonding a boron atom to an organic group, and in the case of containing a reactive group (in the case of the general formula (3'), the adhesion water resistance of the polarizing film is improved, and thus is preferable. The organic group specifically refers to an organic group having 1 to 20 carbon atoms which may have a substituent, and more specifically, examples thereof include: a linear or branched alkylene group optionally having a substituent of 1 to 20 carbon atoms, a cyclic alkylene group optionally having a substituent of 3 to 20 carbon atoms, a phenylene group optionally having a substituent of 6 to 20 carbon atoms, a naphthylene group optionally having a substituent of 10 to 20 carbon atoms, and the like.
Examples of the compound represented by the general formula (3) include, in addition to the above-mentioned compounds, esters of (meth) acrylic acid esters and boric acid, such as esters of hydroxyethyl acrylamide and boric acid, esters of hydroxyethyl acrylate and boric acid, and esters of hydroxybutyl acrylate and boric acid.
The cationically polymerizable compounds used in the cationically polymerizable curable resin composition may be classified into monofunctional cationically polymerizable compounds having 1 cationically polymerizable functional group in the molecule and polyfunctional cationically polymerizable compounds having 2 or more cationically polymerizable functional groups in the molecule. Since the monofunctional cationically polymerizable compound has a low liquid viscosity, the liquid viscosity can be reduced by incorporating the monofunctional cationically polymerizable compound in the cationically polymerizable curable resin composition. In addition, the monofunctional cationically polymerizable compound often has a functional group exhibiting various functions, and by including the monofunctional cationically polymerizable compound in the cationically polymerizable curable resin composition, various functions can be exhibited in the cationically polymerizable curable resin composition and/or the cured product of the cationically polymerizable curable resin composition. The polyfunctional cationically polymerizable compound can crosslink the cured product of the cationically polymerizable curable resin composition in 3 dimensions, and therefore, it is preferable to contain the polyfunctional cationically polymerizable compound in the cationically polymerizable curable resin composition. The ratio of the monofunctional cationically polymerizable compound to the polyfunctional cationically polymerizable compound is preferably in the range of 10 to 1000 parts by weight relative to 100 parts by weight of the monofunctional cationically polymerizable compound. Examples of the cationically polymerizable functional group include an epoxy group, an oxetanyl group, and a vinyl ether group. Examples of the compound having an epoxy group include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds, and particularly, alicyclic epoxy compounds are preferably contained as the cationically polymerizable adhesive composition of the present invention because of excellent curability and adhesiveness. Examples of the alicyclic epoxy compound include 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, caprolactone-modified 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, trimethylcaprolactone-modified valerolactone-modified product, and the like, and specifically include CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2083, CELLOXIDE 2085 (manufactured by the company of the large celluloid chemical industry, ltd., above), cyracure UVR-6105, cyracure UVR-6107, cyracure 30, R-6110 (manufactured by the company Dow Chemical Japan ltd, above), and the like. The compound having an oxetanyl group is preferably contained because of the effect of improving the curability of the cationically polymerizable curable adhesive composition and reducing the liquid viscosity of the composition. Examples of the oxetanyl group-containing compound include 3-ethyl-3-hydroxymethyloxetane, 1, 4-bis [ (3-ethyl-3-oxetanyl) methoxymethyl ] benzene, 3-ethyl-3- (phenoxymethyl) OXETANE, bis [ (3-ethyl-3-oxetanyl) methyl ] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) OXETANE, novolak OXETANE and the like, and ARON OXETANE OXT-101, ARON OXETANE OXT-121, ARON OXETANE OXT-211, ARON OXETANE OXT-221, ARON OXETANE OXT-212 (manufactured by Toyama Co., ltd.) and the like are commercially available. The compound having a vinyl ether group is preferably contained because of the effect of improving the curability of the cationically polymerizable adhesive composition and reducing the liquid viscosity of the composition. Examples of the compound having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, pentaerythritol-type tetravinyl ether, and the like.
The cationic polymerization curable resin composition contains, as a curable component, at least 1 compound selected from the group consisting of the epoxy group-containing compound, the oxetanyl group-containing compound, and the vinyl ether group-containing compound described above, which are all cured by cationic polymerization, and therefore a photo-cationic polymerization initiator is blended. The photo cation polymerization initiator generates cation species or Lewis acid by irradiation of active energy rays such as visible light, ultraviolet rays, X rays, electron beams and the like, thereby initiating polymerization reaction of epoxy groups and oxetane groups. As the photo cation polymerization initiator, a photo acid generator described later can be suitably used. In addition, when the cationically polymerizable adhesive composition is used as the visible light curability, it is particularly preferable to use a photo-cationic polymerization initiator having high sensitivity to light of 380nm or more, but since the photo-cationic polymerization initiator is a compound that normally exhibits a great absorption in a wavelength region around 300nm or shorter than 300nm, the generation of a cationic species or acid from the photo-cationic polymerization initiator can be promoted by blending a photosensitizer that exhibits a great absorption in a wavelength region longer than it, specifically in a wavelength longer than 380nm, and light of a wavelength in the vicinity thereof can be induced. Examples of the photosensitizer include: the anthracene compound, pyrene compound, carbonyl compound, organic sulfur compound, polysulfide, redox compound, azo and diazo compound, halogen compound, photoreductive pigment, etc., and may be used in combination of 2 or more kinds. In particular, anthracene compounds are excellent in photosensitizing effect, and thus are preferable, and specific examples thereof include Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki chemical Co., ltd.). The content of the photosensitizer is preferably 0.1 to 5 wt%, more preferably 0.5 to 3 wt%.
The polarizing film of the present invention can be produced, for example, by a method for producing a polarizing film comprising:
a polarizer manufacturing step of manufacturing a polarizer having a non-polarizing portion formed in at least a part thereof by treating a predetermined position on one surface of the polarizer with a treatment liquid; a 1 st coating step of coating a curable resin composition on the surface of the polarizer, the surface being treated with the treatment liquid; a 1 st bonding step of bonding a 1 st transparent protective film to the surface of the polarizer coated with the curable resin composition; a 2 nd coating step of coating a curable resin composition on a surface of the polarizer opposite to the surface treated with the treatment liquid; a 2 nd bonding step of bonding a 2 nd transparent protective film to the surface of the polarizer coated with the curable resin composition; and a bonding step of bonding the polarizer and the transparent protective film together through an adhesive layer obtained by irradiating the curable resin composition with active energy rays from the 1 st transparent protective film surface side and/or the 2 nd transparent protective film surface side. The polarizer manufacturing process may further include: a step 1 of temporarily bonding a surface protective film having a through hole to one surface of the polarizer to form a polarizing film laminate; a step 2 of treating a predetermined position on one surface of the polarizer with a treatment liquid through the through-hole of the surface protective film to form a non-polarizing portion having a concave portion on one surface; and a 3 rd step of removing the surface protective film from the polarizer.
As a method of applying the curable resin composition to the surface of the polarizer treated with the treatment liquid, it is preferable to use a post-measurement application method from the viewpoints of foreign matter removal and application property on the surface of the polarizer, since the composition viscosity and the target thickness can be appropriately selected. Specific examples of the post-measurement coating method include a gravure roll coating method, a forward roll coating method, an air knife coating method, and a bar/stick coating method. Among these, the gravure roll coating method is particularly preferable from the viewpoints of foreign matter removal and coatability on the surface of the transparent protective film.
The easy-to-adhere composition may be applied to the coated surface of the adhesive composition of the polarizer before the above-mentioned coating step. As a method of applying the adhesive composition to the bonding surface of the polarizer, a post-application measurement application method is preferable in terms of exerting the same effects as those of the application step described above. In the case where the easy-to-adhere composition contains the compound represented by the general formula (3), the adhesion between the polarizer and the transparent protective film is preferably improved.
In the gravure roll coating method, various patterns may be formed on the surface of the gravure roll, for example, a honeycomb net pattern, a trapezoidal pattern, a lattice pattern, a tapered pattern, a diagonal pattern, or the like may be formed. In order to effectively prevent the appearance defect of the finally obtained polarizing film, the pattern formed on the surface of the gravure roll is preferably a honeycomb net pattern. In the case of the honeycomb net pattern, the cell volume is preferably 1 to 5cm in order to improve the surface accuracy of the coated surface after the application of the easy-to-adhere composition 3 /m 2 More preferably 2 to 3cm 3 /m 2 . Similarly, in order to improve the surface accuracy of the coated surface after the application of the adhesive composition, the number of unit lines per 1 inch of roller is preferably 200 to 3000 lines/inch. The rotation speed ratio of the gravure roll is preferably 100 to 300% relative to the traveling speed of the polarizer.
The polarizer and the transparent protective film are bonded via the curable resin composition applied as described above. The lamination of the polarizer and the transparent protective film can be performed by a roll laminator or the like.
After the polarizer and the transparent protective film are bonded, active energy rays (e.g., electron beam, ultraviolet ray, visible light, etc.) are irradiated to cure the curable resin composition, thereby forming an adhesive layer. The irradiation direction of the active energy rays (electron beam, ultraviolet ray, visible light, etc.) may be irradiated from any appropriate direction, and is preferably irradiated from the transparent protective film side. If the light is irradiated from the polarizer side, there is a concern that the polarizer is deteriorated by active energy rays (electron beam, ultraviolet ray, visible light, etc.).
The irradiation conditions for the irradiation of the electron beam may be any conditions as long as the curable resin composition can be cured. For example, the acceleration voltage of electron beam irradiation is preferably 5kV to 300kV, more preferably 10kV to 250kV. If the acceleration voltage is less than 5kV, there is a concern that the electron beam cannot reach the adhesive and curing is insufficient, and if the acceleration voltage is more than 300kV, there is a concern that the penetration force through the sample is too strong, and the transparent protective film and the polarizer may be damaged. The irradiation dose is 5 to 100kGy, more preferably 10 to 75kGy. When the irradiation dose is less than 5kGy, the curing of the adhesive is insufficient, and when the irradiation dose is more than 100kGy, the transparent protective film and the polarizer are damaged, the mechanical strength is lowered, and yellowing occurs, so that the given optical characteristics cannot be obtained.
The electron beam irradiation is usually performed in an inert gas, and may be performed in the atmosphere with a small amount of oxygen introduced as needed. According to the material of the transparent protective film, oxygen is appropriately introduced to cause oxygen inhibition on the surface of the transparent protective film irradiated with the electron beam, so that damage to the transparent protective film can be prevented, and the electron beam can be efficiently irradiated only to the adhesive.
In the above-mentioned method for producing a polarizing film, it is preferable to use an active energy ray containing visible light having a wavelength of 380nm to 450nm, in particular, an active energy ray having the maximum irradiation amount of visible light having a wavelength of 380nm to 450nm as an active energy ray. When ultraviolet light or visible light is used, the use of a transparent protective film (ultraviolet-opaque transparent protective film) having ultraviolet absorption capability absorbs light having a wavelength shorter than 380nm, and therefore, light having a wavelength shorter than 380nm does not reach the adhesive composition, and does not contribute to polymerization reaction. The light having a wavelength shorter than 380nm absorbed by the transparent protective film is converted into heat, and the transparent protective film itself generates heat, which causes defects such as curling and wrinkling of the polarizing film. Therefore, in the present invention, when ultraviolet light or visible light is used, a device that does not emit light having a wavelength shorter than 380nm is preferably used as the active energy ray generation device, and more specifically, the ratio of the cumulative illuminance in the wavelength range of 380 to 440nm to the cumulative illuminance in the wavelength range of 250 to 370nm is preferably 100:0 to 100:50, and more preferably 100:0 to 100:40. In the method for producing a polarizing film of the present invention, a metal halide lamp in which gallium is enclosed, an LED light source that emits light in the wavelength range of 380 to 440nm, or a light source including ultraviolet light and visible light such as a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, an incandescent lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a metal halide lamp, a fluorescent lamp, a tungsten lamp, a gallium lamp, an excimer laser, or sunlight may be used as the active energy ray, and ultraviolet light having a wavelength shorter than 380nm may be blocked by a band-pass filter. In order to improve the adhesion performance of the adhesive layer between the polarizer and the transparent protective film and to prevent curling of the polarizing film, it is preferable to use a metal halide lamp in which gallium is enclosed, and to use active energy rays obtained by a band-pass filter capable of blocking light having a wavelength shorter than 380nm, or active energy rays having a wavelength of 405nm obtained by an LED light source.
The adhesive composition is preferably heated before irradiation with ultraviolet light or visible light (heating before irradiation), in which case it is preferably heated to 40 ℃ or higher, more preferably 50 ℃ or higher. The active energy ray-curable adhesive composition is preferably heated after irradiation with ultraviolet light or visible light (post-irradiation heating), and in this case, it is preferably heated to 40 ℃ or higher, more preferably 50 ℃ or higher.
The polarizing film of the present invention can be used in practice as an optical film laminated with other optical layers. The optical layer is not particularly limited, and for example, 1 or 2 or more layers of reflective plates, semi-transmissive plates, phase difference plates (including 1/2 wave plates, 1/4 wave plates, and the like), viewing angle compensation films, and the like may be used in some cases in the formation of image display devices and the like. Particularly preferred are a reflective polarizing film or a semi-transmissive polarizing film in which a reflective plate or a semi-transmissive reflective plate is further laminated on the polarizing film of the present invention, an elliptical polarizing film or a circular polarizing film in which a phase difference plate is further laminated on the polarizing film, a wide viewing angle polarizing film in which a viewing angle compensation film is further laminated on the polarizing film, and a polarizing film in which a brightness enhancement film is further laminated on the polarizing film.
The optical film formed by laminating the optical layers on the polarizing film may be formed by laminating the optical layers one by one in the process of manufacturing an image display device or the like, but the optical film formed by laminating the optical layers in advance has the advantage of excellent quality stability, assembly operation or the like, and thus the process of manufacturing the image display device or the like can be improved. An appropriate bonding method such as an adhesive layer may be used for lamination. In the case of bonding the polarizing film and the other optical film, the optical axes thereof may be arranged at an appropriate angle according to the target phase difference characteristic or the like.
An adhesive layer for adhesion to other members such as a liquid crystal cell may be provided on the polarizing film or the optical film in which at least 1 polarizing film is laminated. The binder for forming the adhesive layer is not particularly limited, and for example, an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, a rubber-based polymer, or the like can be appropriately selected and used as the binder for the base polymer. An adhesive such as an acrylic adhesive having excellent optical transparency and having suitable adhesive properties such as wettability, cohesiveness and adhesiveness and excellent weather resistance and heat resistance can be particularly preferably used.
The adhesive layer may be provided on one side or both sides of the polarizing film, the optical film in the form of a laminate of layers of different compositions, kinds, or the like. In the case of providing the polarizing film and the optical film on both surfaces, adhesive layers having different compositions, types, thicknesses, and the like may be formed on the front surface and the back surface of the polarizing film and the optical film. The thickness of the adhesive layer may be appropriately determined depending on the purpose of use, adhesive strength, etc., and is usually 1 to 100. Mu.m, preferably 5 to 30. Mu.m, particularly preferably 10 to 20. Mu.m.
The exposed surface of the adhesive layer is temporarily bonded to and covers the separator for the purpose of preventing contamination or the like until it is put to practical use. This can prevent contact with the adhesive layer in a normal processing state. As the separator, a separator which is obtained by coating a suitable thin layer body such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, a net, a foam sheet, a metal foil, or a laminate thereof with a suitable release agent such as silicone, long-chain alkyl, fluorine, or molybdenum sulfide, if necessary, in addition to the above thickness conditions, may be used.
[ image display device ]
The polarizing film of the present invention can be preferably used for formation of various devices such as an image display device. The image display device can be formed according to the conventional method. That is, the image display device is generally formed by appropriately assembling a liquid crystal cell, a polarizing film or an optical film, and, if necessary, components such as an illumination system, and incorporating a driving circuit, etc., and in the present invention, the polarizing film or the optical film of the present invention is not particularly limited, and may be carried out according to a conventional method. As the liquid crystal cell, any type of liquid crystal cell such as a TN type, an STN type, a pi type, or the like can be used.
An image display device in which a polarizing film or an optical film is disposed on one side or both sides of a liquid crystal cell, a liquid crystal display device in which a backlight or a reflective plate is used in an illumination system, or the like can be suitably formed. In this case, the polarizing film or the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. In the case where polarizing films or optical films are provided on both sides, they may be the same or different. Further, in the formation of the image display device, appropriate members such as a diffusion plate, an antiglare layer, an antireflection film, a protection plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight may be disposed at appropriate positions for 1 layer or 2 layers or more. Further, examples of the image display device of the present invention include: organic EL (electroluminescence) display devices, PDPs (plasma display panels), electronic papers, and the like are particularly preferably used in organic EL using a high-transmittance polarizer. Further, the image display device is preferably used for a foldable display device or a vehicle-mounted display device, which requires a member having durability against a high humidity and heat environment.
Since the polarizing film of the present invention has the non-polarizing portion formed on the polarizer, the polarizing film can be applied particularly to an image display device having a sensor function, and in this case, the non-polarizing portion of the polarizing film is disposed at a position corresponding to the camera portion.
Examples
Examples of the present invention are described below, but the embodiments of the present invention are not limited to these.
< polarizing film manufacture >)
Examples 1 to 2
As a resin base material, an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a long shape, a water absorption of 0.75% and a Tg of 75℃was used. A laminate was produced by applying a corona treatment to one surface of a substrate, and applying an aqueous solution containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl-modification ratio 4.6%, saponification degree 99.0 mol% or more, manufactured by japan chemical industry co., ltd., trade name "gossamer Z200") at a ratio of 9:1 to the corona-treated surface at 25 ℃ and drying the aqueous solution to form a PVA-based resin layer having a thickness of 13 μm.
The obtained laminate was subjected to free-end unidirectional stretching (auxiliary stretching in a gas atmosphere) in an oven at 120 ℃ between rolls having different peripheral speeds, the stretching being performed to 2.4 times in the longitudinal direction (longitudinal direction). Next, the laminate was immersed in an insolubilization bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30 ℃ for 30 seconds (insolubilization treatment). Next, in a dyeing bath having a liquid temperature of 30 ℃, the iodine concentration and the dipping time were adjusted and dipping was performed so that the polarizer reached a given transmittance. In this example, an aqueous iodine solution obtained by adding 0.2 part by weight of iodine to 100 parts by weight of water and 1.5 parts by weight of potassium iodide was immersed for 60 seconds (dyeing treatment). Then, the resultant solution was immersed in a crosslinking bath (aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide with 100 parts by weight of water and 3 parts by weight of boric acid) at a liquid temperature of 30℃for 30 seconds (crosslinking treatment). Then, the laminate was immersed in an aqueous boric acid solution (aqueous solution obtained by mixing 3 parts by weight of boric acid with 5 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 70 ℃ and uniaxially stretched (stretched in aqueous solution) between rolls having different peripheral speeds along the longitudinal direction (longitudinal direction) so that the total stretching ratio became 5.5 times. Then, the laminate was immersed in a washing bath (aqueous solution obtained by mixing 100 parts by weight of water with 4 parts by weight of potassium iodide) at a liquid temperature of 30 ℃ (washing treatment).
Next, in example 1, an easy-to-adhere composition 2 (coating thickness 1 μm) was coated on the surface of the PVA-based resin layer of the laminate using a gravure roll coating method having a gravure roll, and the laminate was air-dried at 25 ℃ for 1 minute (thickness 0.5 μm after drying).
Next, in examples 1 and 2, an adhesive composition 2 or 3 was applied to the surface of the laminate of PVA-based resin layer (the surface of the laminate of PVA-based resin layer having a thickness of 17 μm) of ZEONOR-based resin film (thickness of 17 μm) manufactured by the company re Weng Zhushi, which constitutes the 2 nd transparent protective film, and the following ultraviolet rays were irradiated from the ZEONOR-based resin film side to cure the adhesive. The thickness of the cured adhesive layer is shown in table 2. In the present invention, the thickness between the polarizer and the transparent protective film is defined as the adhesive layer thickness, regardless of whether the adhesive layer is composed of an adhesive alone or an adhesive layer composed of an adhesive and an adhesive composition that is easy to adhere. The method for measuring the thickness of the adhesive layer will be described later. The compositions of the adhesive compositions 1 to 3 and the easy-to-adhere compositions 1 to 2 are shown in Table 1.
Then, the base material was peeled off from the PVA-based resin layer to obtain a polarizing film (polarizer/2 nd transparent protective film) in a long form having a width of about 1300 mm. The thickness of the polarizer was 5. Mu.m, and the transmittance of the monomer was 40.8%.
The constituent materials shown in table 1 are as follows.
ACMO (acryloylmorpholine); trade names "ACMO", manufactured by KJ chemical Co., ltd
1,9-NDA (1, 9-nonanediol diacrylate), trade names "LIGHT ACRYLATE, 9ND-A", manufactured by Kagaku chemical Co., ltd.)
P2H-a (phenoxy diethylene glycol acrylate); trade name "LIGHT ACRYLATE P H-A", manufactured by Kagaku Co., ltd
HEAA (hydroxyethyl acrylamide); trade name "HEAA", from Xinghu Co., ltd
BYK UV3505 (UV curable surface conditioner); trade name "BYK UV3505", manufactured by BYK Japan Co., ltd
Or907 (2-methyl-1- [4- (methylthio) phenyl ] -2-morpholino-1-propanone); trade name "Omnirad907", manufactured by IGMresins Co
DETX (diethylthioxanthone); trade name "KAYACURE DETX-S", manufactured by Japanese Kagaku Kogyo Co., ltd
UP-1190 (acrylic oligomer obtained by polymerizing (meth) acrylic monomer); trade name "ARUFON UP1190", manufactured by Toyo Kagaku Co., ltd
Or819 (bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide); trade name "Omnirad 819", IGM
VPBA (4-vinylphenylboronic acid); trade name "4-vinylphenylboronic acid", manufactured by tokyo chemical industry Co., ltd
HPAA (hydroxypivalic acid diacrylate); trade name "LIGHT ACRYLATE HPPA", manufactured by co-Rong chemical Co., ltd
M5700 (2-hydroxy-3-phenoxypropyl acrylate); trade name "ARONIX M5700", manufactured by Toyama Synthesis Co., ltd
DEAA (diethyl acrylamide); trade name "DEAA", manufactured by KJ chemical Co., ltd
EXP4200 (leveling agent); trade name "Olfine EXP.4200", manufactured by Nissan chemical industry Co., ltd. (ultraviolet ray)
As the active energy rays, an ultraviolet (gallium-enclosed metal halide lamp) irradiation device was used: fusion UVSystems, inc. Light HAMMER10, valve: v valve, peak illuminance: 1600mW/cm 2 Cumulative exposure of 1000/mJ/cm 2 (wavelength 380-440 nm). The illuminance of ultraviolet light was measured using a Sola-Check system manufactured by Solatell corporation.
An adhesive (acrylic adhesive) was applied to one side of an ester resin film (thickness 38 μm) having a width of about 1300mm so that the thickness was 5 μm. Through holes having a diameter of 2.8mm were formed in the adhesive resin film at intervals of 250mm in the longitudinal direction and 400mm in the width direction using a sharp knife.
The adhesive-equipped ester resin film was bonded to the polarizer side of the obtained polarizing film in a roll-to-roll manner, immersed in 1mol/L (1N) aqueous sodium hydroxide solution for 30 seconds, and then immersed in 1mol/L (1N) hydrochloric acid for 10 seconds. Then, the polarizing plate was dried at 60℃to form a non-polarizing portion on the polarizing plate. The unpolarized portion is a thin portion having a recess with a maximum depth dh of 0.5 μm on the ester resin film side.
The ester resin film was peeled off from the laminate obtained above. Next, in example 1, an easy-to-adhere composition 1 (coating thickness 1 μm) was applied to the release surface by using a gravure roll coating method having a gravure roll, and air-dried at 25 ℃ for 1 minute (thickness 0.7 μm after drying). Next, an acrylic resin film (thickness 40 μm) manufactured by eastern Steel sheet Co., ltd., transparent protective film 1 was coated with an adhesive composition 1 or 3, and the coated surface of the laminate was bonded to the easily bondable composition 1 in example 1, and the peeled surface of the ester resin film of the laminate was bonded to example 2, and the adhesive was cured by irradiation of ultraviolet rays similar to those described above. The thickness of the cured adhesive layer is shown in table 2.
Thus, a polarizing film having a structure of 1 st transparent protective film/polarizer/2 nd transparent protective film was produced. The 1 st transparent protective film corresponds to the transparent protective film 3 constituting the polarizing film 10 shown in fig. 1, the polarizer corresponds to the polarizer 2 constituting the polarizing film 10 shown in fig. 1, and the adhesive layer bonding the 1 st transparent protective film and the polarizer corresponds to the adhesive layer 1 constituting the polarizing film 10 shown in fig. 1. The 2 nd transparent protective film corresponds to the transparent protective film 5 constituting the polarizing film 10 shown in fig. 1, and the adhesive layer for bonding the 2 nd transparent protective film and the polarizer corresponds to the adhesive layer 4 constituting the polarizing film 10 shown in fig. 1. The measurement results of the thickness and physical properties of the obtained polarizing film are shown in table 2.
In table 2, the thickness d1 (μm) of the 1 st adhesive layer, the thickness d2 (μm) of the non-polarizing portion of the polarizer, and the thickness d4 (μm) of the 2 nd adhesive layer were measured using a scanning electron microscope (manufactured by ZYGO corporation, product name "New View 7300"). The thickness d3 (μm) of the 1 st transparent protective film and the thickness d5 (μm) of the 2 nd transparent protective film were measured using a digital micrometer (product name "KC-351C", manufactured by Anritsu Co., ltd.).
In Table 2, the indentation elastic moduli E1 (25) to E5 (25) measured at 25℃were measured by the following methods.
The slope (S) of a tangent line of a load release curve at the time of releasing a load and the area (contact projection area) (A) of the indenter for use in the test portion were measured by using a nanoindenter (manufactured by Bruker Japan Co., ltd., triboindeter TI-950) to press the indenter (model TI-0039; manufactured by Bruker Japan Co., ltd., triboindeter TI-950) into the center portion of each portion of the polarizing film to be measured (for example, the center portion in the thickness direction of the 1 st adhesive layer in the case of measuring the press-in elastic modulus E1 of the 1 st adhesive layer) by using a nanoindenter (model TI-0039; manufactured by Bercovici type diamond indenter, front opening angle 142.3 ℃) and then the press-in elastic modulus (GPa) was calculated based on the following formula.
(indentation elastic modulus (GPa))= (vpi/2) × (S/a)
For measurement of the press-in elastic modulus E2 of the polarizer, a cross section of the polarizer parallel to the TD direction was prepared, and the press head was pressed in the MD direction, thereby calculating the press-in elastic modulus (GPa).
In table 2, press-in hardness H3 (25) and H5 (25) measured at 25 ℃ were measured by the following methods.
The maximum load (Pmax) and the area (contact projection area) (a) of the indenter (Bercovici type TI-950, manufactured by Bruker Japan, ltd.) were measured by pressing a indenter (model TI-0039; bercovici type diamond indenter, tip opening angle 142.3 °) into the center portion of each portion of the polarizing film to be measured (for example, the center portion in the thickness direction of the 1 st transparent protective film when the press-in hardness H3 of the 1 st transparent protective film was measured) by using a nanoindenter (bercovicter TI-950, manufactured by Bruker Japan, ltd.) at 50nm, and the hardness (GPa) was calculated based on the following.
(hardness (GPa)) = (Pmax)/(a)
In order to evaluate crack resistance of the polarizer in a severe temperature environment, a thermal shock test shown below was performed.
< thermal shock test >)
An adhesive layer was provided on the transparent protective film side of the polarizing films of examples 1-2, and a polarizing film with an adhesive layer was prepared. Using CO 2 As shown in FIG. 2, a polarizing film (sample size: 5 cm. Times.5 cm) with an adhesive layer, in which a non-polarizing portion 1A was formed at a position 1cm from the center end, was cut out by Laser (product name: laser Pro-SPIRIT, manufactured by COMNET Co., ltd.) and bonded to alkali-free glass having a thickness of 0.5mm, to prepare a sample. After the sample was subjected to thermal shock at-40 to 85 ℃ for 30 minutes×100 times, the presence or absence of occurrence of cracks at the boundary portion between the non-polarizing portion 1A and the polarizing portion was confirmed, and this test was referred to as "thermal shock test 1". After the sample was put into an environment where thermal shock was performed at-40 to 85 ℃ for 30 minutes×200 times, the presence or absence of occurrence of cracks at the boundary portion between the non-polarizing portion 1A and the polarizing portion was confirmed, and this test was referred to as "thermal shock test 2". "thermal shock test 2" is a more severe test than "thermal shock test 1". These tests were performed 5 times, and the crack resistance of the polarizer was evaluated based on the number of samples in which cracks were generated among the number of samples charged. CO 2 The irradiation conditions of the laser light are as follows.
(irradiation conditions)
Wavelength: 10.6 μm
Laser output power: 30W
Oscillation mode: pulse oscillation
Diameter of laser: 70 μm
Laser irradiation surface: protective film side
As is clear from the description in table 2, in any of examples 1 to 2, no crack was generated at the boundary portion between the unpolarized section 1A and the polarized section after the thermal shock test, and the polarizer was excellent in crack resistance even in a severe temperature environment.
< polarizing film manufacture >)
Examples 3, 4, 6, comparative example 1
As a resin base material, an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a long shape, a water absorption of 0.75% and a Tg of 75℃was used. A laminate was produced by applying a corona treatment to one surface of a substrate, and applying an aqueous solution containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl-modification ratio 4.6%, saponification degree 99.0 mol% or more, manufactured by japan chemical industry co., ltd., trade name "gossamer Z200") at a ratio of 9:1 to the corona-treated surface at 25 ℃ and drying the aqueous solution to form a PVA-based resin layer having a thickness of 13 μm.
The obtained laminate was subjected to free-end unidirectional stretching (auxiliary stretching in a gas atmosphere) in an oven at 120 ℃ between rolls having different peripheral speeds, the stretching being performed to 2.4 times in the longitudinal direction (longitudinal direction). Next, the laminate was immersed in an insolubilization bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30 ℃ for 30 seconds (insolubilization treatment). Next, the polarizer was immersed in a dyeing bath at a liquid temperature of 30 ℃ with the iodine concentration and immersion time adjusted so that the polarizer reached a predetermined transmittance. In this example, an aqueous iodine solution obtained by adding 0.2 part by weight of iodine to 100 parts by weight of water and 1.5 parts by weight of potassium iodide was immersed for 60 seconds (dyeing treatment). Then, the resultant solution was immersed in a crosslinking bath (aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide with 100 parts by weight of water and 3 parts by weight of boric acid) at a liquid temperature of 30℃for 30 seconds (crosslinking treatment). Then, the laminate was immersed in an aqueous boric acid solution (aqueous solution obtained by mixing 3 parts by weight of boric acid with 5 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 70 ℃ and uniaxially stretched (stretched in aqueous solution) between rolls having different peripheral speeds along the longitudinal direction (longitudinal direction) so that the total stretching ratio became 5.5 times. Then, the laminate was immersed in a washing bath (aqueous solution obtained by mixing 100 parts by weight of water with 4 parts by weight of potassium iodide) at a liquid temperature of 30 ℃ (washing treatment).
In example 3, the surface of the PVA-based resin layer of the laminate was coated with an easy-to-adhere composition 2 (coating thickness 1 μm) by using a gravure roll coating method having a gravure roll before the surface of the PVA-based resin layer of the laminate was bonded to the 2 nd transparent protective film, and then air-dried at 25℃for 1 minute (thickness 0.5 μm after drying). Next, an adhesive composition constituting the 2 nd adhesive layer was applied to the film (2) (acrylic resin film (thickness 40 μm) manufactured by eastern steel plate corporation) or the film (3) (cellulose triacetate resin film (thickness 25 μm) manufactured by fuji film corporation), the PVA resin layer surface of the laminate was bonded to the adhesive coated surface of the 2 nd transparent protective film in examples 4, 6 and comparative example 1, and the coated surface of the easily bonded composition 2 was bonded to the adhesive coated surface of the 2 nd transparent protective film in example 3, and the following ultraviolet rays were irradiated from the 2 nd transparent protective film side to cure the adhesive. The thickness of the cured adhesive layer is shown in table 4. The composition of the adhesive composition as the raw materials for the 1 st adhesive layer and the 2 nd adhesive layer is shown in table 3.
Then, the base material was peeled off from the PVA-based resin layer to obtain a polarizing film (polarizer/2 nd transparent protective film) in a long form having a width of about 1300 mm. The thickness of the polarizer was 5. Mu.m, and the transmittance of the monomer was 40.8%.
Of the constituent materials shown in table 3, materials other than the constituent materials shown in table 1 are as follows.
FA1DDM (unsaturated fatty acid hydroxyalkyl ester modified epsilon-caprolactone (monomer component with hydroxyl group)); trade name "PLACCEL FA DDM", manufactured by Daxie Kagaku Co., ltd
9EGA (PEG 400# Diacrylate); ext> tradeext> nameext> "ext> LIGHText> ACRYLATEext> EGext> -ext> Aext>"ext>,ext> manufacturedext> byext> Kagakuext> Coext>.ext>,ext> Ltdext>
(ultraviolet ray)
As the active energy rays, an ultraviolet (gallium-enclosed metal halide lamp) irradiation device was used: fusion UVSystems, inc. Light HAMMER10, valve: v valve, peak illuminance: 1600mW/cm 2 Cumulative exposure of 1000/mJ/cm 2 (wavelength 380-440 nm). The illuminance of ultraviolet light was measured using a Sola-Check system manufactured by Solatell corporation.
An adhesive (acrylic adhesive) was applied to one side of an ester resin film (thickness 38 μm) having a width of about 1300mm so that the thickness was 5 μm. Through holes having a diameter of 2.8mm were formed in the adhesive resin film at intervals of 250mm in the longitudinal direction and 400mm in the width direction using a sharp knife.
The adhesive-equipped ester resin film was bonded to the polarizer side of the obtained polarizing film in a roll-to-roll manner, immersed in 1mol/L (1N) aqueous sodium hydroxide solution for 30 seconds, and then immersed in 1mol/L (1N) hydrochloric acid for 10 seconds. Then, the polarizing plate was dried at 60℃to form a non-polarizing portion on the polarizing plate. The unpolarized portion is a thin portion having a recess with a maximum depth dh of 0.5 μm on the ester resin film side.
The ester resin film was peeled off from the laminate obtained above. Next, in examples 4 and 6, an easy-to-adhere composition 1 (coating thickness 1 μm) was applied to the release surface by using a gravure roll coating method having a gravure roll, and the film was air-dried at 25 ℃ for 1 minute (thickness 0.7 μm after drying). Next, the adhesive composition constituting the 1 st adhesive layer was applied to the 1 st transparent protective film (1) (ZEONOR resin film (17 μm thick) manufactured by rex Weng Zhushi), the film (2) (acrylic resin film (40 μm thick) manufactured by eastern steel sheet corporation) or the film (3) (cellulose triacetate resin film (25 μm thick) manufactured by fuji film corporation), and was bonded to the application surface of the laminate of the easy-to-adhere composition 1 in examples 4 and 6, and was bonded to the release surface of the laminate of the ester resin film in example 3 and comparative example 1, and the same ultraviolet rays as described above were irradiated from the 1 st transparent protective film side, whereby the adhesive was cured. The thickness of the cured adhesive layer is shown in table 4.
Thus, a polarizing film having a structure of 1 st transparent protective film/polarizer/2 nd transparent protective film was produced. The 1 st transparent protective film corresponds to the transparent protective film 3 constituting the polarizing film 10 shown in fig. 1, the polarizer corresponds to the polarizer 2 constituting the polarizing film 10 shown in fig. 1, and the adhesive layer bonding the 1 st transparent protective film and the polarizer corresponds to the adhesive layer 1 constituting the polarizing film 10 shown in fig. 1. The 2 nd transparent protective film corresponds to the transparent protective film 5 constituting the polarizing film 10 shown in fig. 1, and the adhesive layer for bonding the 2 nd transparent protective film and the polarizer corresponds to the adhesive layer 4 constituting the polarizing film 10 shown in fig. 1. The measurement results of the thickness and physical properties of the obtained polarizing film are shown in table 4.
Example 5
First, instead of producing a polarizer/2 nd transparent protective film through the 2 nd adhesive layer, an easy-to-adhere composition 1 (coating thickness 1 μm) was coated on the surface of the PVA-based resin layer of the laminate by using a gravure roll coating method having a gravure roll, and then the layer was air-dried at 25 ℃ for 1 minute (thickness 0.7 μm after drying), and the easy-to-adhere composition 1-forming surface and the 1 st transparent protective film were laminated with the 1 st adhesive layer interposed therebetween, thereby producing a polarizer/1 st transparent protective film, and then a polarizing film having a 1 st transparent protective film/2 nd transparent protective film was produced in the same manner as in examples 3, 4, 6, and 1 by using a method of producing a polarizing film in which an unpolarized portion was formed on the polarizer, an easy-to-adhere composition 2 (coating thickness 1 μm) was coated on the unpolarized portion-forming surface of the polarizer by using a gravure roll coating method having a gravure roll, and then the easy-to-adhere composition 2 forming surface and the layer was laminated with the 2 nd transparent protective film interposed by air-drying at 25 ℃ for 1 minute (thickness 0.5 μm after drying).
In table 4, the thickness d1 (μm) of the 1 st adhesive layer, the thickness d2 (μm) of the non-polarizing portion of the polarizer, and the thickness d4 (μm) of the 2 nd adhesive layer, the press-in elastic moduli E1 (25) to E5 (25) measured at 25 ℃, the press-in elastic modulus E2 of the polarizer, the press-in hardness H3 (25) and H5 (25) measured at 25 ℃, and the thermal shock test method were measured and evaluated by the same methods as in examples 1 to 2.
As is clear from the description in table 4, in any of examples 3 to 6, cracks were not generated at the boundary portion between the unpolarized section 1A and the polarized section after the thermal shock test, and the crack resistance of the polarizer was excellent even in a severe temperature environment, as compared with comparative example 1.

Claims (7)

1. A polarizing film comprising a 1 st transparent protective film laminated on one surface of a polarizer via a 1 st adhesive layer,
the polarizer is formed with a non-polarizing portion at least a portion thereof,
the following formula (1) is satisfied when the press-in elastic modulus (25 ℃) of the 1 st adhesive layer is E1 (25) (GPa), the press-in elastic modulus (25 ℃) of the unpolarized portion is E2 (25) (GPa), and the press-in elastic modulus (25 ℃) of the 1 st transparent protective film is E3 (25) (GPa):
(E1(25)×E3(25)) (1/2) ≥0.2×E2(25) (1)。
2. the polarizing film of claim 1, wherein,
a 2 nd transparent protective film is laminated on the other surface of the polarizer through a 2 nd adhesive layer,
when the press-in hardness (25 ℃) of the 2 nd transparent protective film is H5 (25) (GPa) and the press-in hardness (25 ℃) of the 1 st transparent protective film is H3 (25) (GPa),
H3(25)＞H5(25)。
3. the polarizing film according to claim 2, wherein,
when the press-in elastic modulus (25 ℃) of the 2 nd transparent protective film is E5 (25) (GPa) and the thickness of the 2 nd transparent protective film is d5 (μm),
E5(25)×d5＜200。
4. The polarizing film according to claim 2, wherein,
when the press-in elastic modulus (25 ℃) of the 2 nd adhesive layer is E4 (25) (GPa) and the thickness is d4 (μm),
E4(25)×d4＜10。
5. the polarizing film of claim 1, wherein,
when the press-in elastic modulus (80 ℃) of the 1 st adhesive layer is E1 (80) (GPa),
E1(80)/E1(25)＞0.5。
6. the polarizing film of claim 1, wherein,
when the thickness of the adhesive layer between the portion of the polarizer other than the non-polarizing portion and the 1 st transparent protective film is d1 (μm),
d1＜2。
7. an image display device comprising the polarizing film according to claim 1, wherein the unpolarized portion of the polarizing film is disposed at a position corresponding to the sensor portion.
CN202280032367.4A 2021-06-30 2022-06-27 Polarizing film and image display device Pending CN117242378A (en)

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