CN110997310A

CN110997310A - Conductive film for transfer

Info

Publication number: CN110997310A
Application number: CN201880051261.2A
Authority: CN
Inventors: 中岛一裕; 菅原英男; 安藤豪彦; 武田健太郎
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2017-08-09
Filing date: 2018-07-10
Publication date: 2020-04-10
Also published as: KR20200018689A; WO2019031138A1; TW201931386A; JP2019031040A

Abstract

Provided is a conductive film for transfer, which is provided with a conductive layer and can produce an optical laminate having excellent bending resistance. The conductive film for transfer printing of the present invention comprises in order: a temporary support, a liquid crystal layer provided so as to be peelable from the temporary support, and a conductive layer. In 1 embodiment, the conductive layer is directly laminated on the liquid crystal layer. In 1 embodiment, the refractive index characteristic of the liquid crystal layer is expressed by nz > nx ≧ ny.

Description

Conductive film for transfer

Technical Field

The present invention relates to a conductive film for transfer.

Background

Conventionally, as electrodes, electromagnetic wave shields, and the like of touch sensors used in mobile devices and the like, transparent conductive films in which a metal oxide layer (conductive layer) such as an indium-tin composite oxide layer (ITO layer) is formed on a substrate such as a transparent resin film (for example, a PET film, a cycloolefin film) have been used in many cases.

On the other hand, in recent years, with the advent of wearable devices, foldable devices, and the like, transparent conductive films having more flexibility and high bending resistance, more specifically, transparent conductive films whose conductive layers are less likely to be damaged even when bent, have been demanded. As a method of improving the bending resistance, a method of reducing stress applied to the conductive layer by thinning the substrate is considered. However, from the viewpoint of handling and the like, the transparent resin film constituting the substrate has a limit, and the limit thickness of the transparent resin film is an obstacle to improvement of the bending resistance. As another method for improving the bending resistance, the use of a transparent conductive thin film having a conductive layer made of a conductive polymer, a metal nanowire, or the like instead of a metal oxide layer which is likely to cause cracks has been studied, but the film has problems in conductivity and transparency, and cannot be introduced into a substrate in a true manner.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4893867

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a conductive film for transfer, which is provided with a conductive layer and can produce an optical laminate having excellent bending resistance.

Means for solving the problems

The conductive film for transfer printing of the present invention comprises in order: a temporary support, a liquid crystal layer provided so as to be peelable from the temporary support, and a conductive layer.

In 1 embodiment, the conductive layer is directly laminated on the liquid crystal layer.

In 1 embodiment, the refractive index characteristic of the liquid crystal layer is expressed by nz > nx ≧ ny.

In 1 embodiment, the thickness of the liquid crystal layer is 0.1 to 10 μm.

In one embodiment, the conductive layer is made of a metal oxide.

In one embodiment, the conductive layer is patterned.

According to yet another aspect of the present invention, an optical stack is provided. The optical laminate comprises, in order: an optical member, an adhesive layer, the conductive layer, and the liquid crystal layer, wherein the conductive layer is directly laminated on the liquid crystal layer.

In 1 embodiment, the optical member is a polarizing plate.

In one embodiment, the optical member is a circularly polarizing plate including: and a retardation layer functioning as a λ/4 plate, wherein the polarizer is disposed on a side of the retardation layer opposite to the conductive layer.

In 1 embodiment, the optical laminate further includes another optical member on a side of the liquid crystal layer opposite to the conductive layer.

In one embodiment, the other optical member is a circularly polarizing plate including: and a retardation layer functioning as a λ/4 plate, the polarizer being disposed on a side of the retardation layer opposite to the liquid crystal layer.

According to still another aspect of the present invention, a touch device is provided. The touch device includes the optical laminate.

According to still another aspect of the present invention, a method of manufacturing an optical laminate is provided. The manufacturing method comprises the following steps: and transferring the laminate including the liquid crystal layer and the conductive layer from the transfer conductive film to an optical member.

ADVANTAGEOUS EFFECTS OF INVENTION

The conductive film for transfer printing of the present invention comprises in order: a temporary support, a liquid crystal layer, and a conductive layer. When the conductive film for transfer having such a structure is used, a laminate including the liquid crystal layer and the conductive layer can be transferred to another optical member to form an optical laminate. The optical laminate obtained has excellent bending resistance because it does not have a rigid substrate (a substrate required for forming the conductive layer). In addition, since the conductive layer is made of a metal oxide, the conductive film for transfer of the present invention has excellent conductivity and light transmittance.

Drawings

Fig. 1 is a schematic cross-sectional view of a conductive thin film for transfer according to 1 embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of an optical stack according to 1 embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view of an optical stack according to yet another embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view of an optical stack according to yet another embodiment of the present invention.

Fig. 5 is a graph showing the results of the bending resistance test in example 1, comparative example 1, and comparative example 2.

Detailed Description

(definition of wording and symbols)

The terms and symbols in the present specification are defined as follows.

(1) Refractive index (nx, ny, nz)

"nx" is a refractive index in a direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is a refractive index in a direction orthogonal to the slow axis in the plane (i.e., the fast axis direction), and "nz" is a refractive index in the thickness direction.

(2) In-plane retardation (Re)

"Re (550)" is an in-plane retardation measured at 23 ℃ with light having a wavelength of 550 nm. For Re (550), assuming that the thickness of the layer (film) is d (nm), the following formula is used: re ═ x-ny) × d. "Re (450)" represents an in-plane retardation measured at 23 ℃ with light having a wavelength of 450 nm.

(3) Retardation in thickness direction (Rth)

"Rth (550)" is a phase difference in the thickness direction measured at 23 ℃ with light having a wavelength of 550 nm. With respect to Rth (550), when the thickness of the layer (film) is d (nm), the following equation is used: and Rth ═ x-nz) × d. "Rth (450)" is a phase difference in the thickness direction measured at 23 ℃ with light having a wavelength of 450 nm.

(4) Coefficient of Nz

The Nz coefficient is obtained by Nz ═ Rth/Re.

A. Integral structure of conductive film for transfer printing

Fig. 1 is a schematic cross-sectional view of a conductive thin film for transfer according to 1 embodiment of the present invention. The transfer conductive film 10 includes, in order: a temporary support 11, a liquid crystal layer 12 provided so as to be peelable from the temporary support 11, and a conductive layer 13. The conductive layer 13 is preferably laminated directly (i.e., without the aid of an adhesive layer or the like) to the liquid crystal layer 12.

The transfer conductive film 10 can be used when a conductive layer is provided to an optical laminate. More specifically, the conductive layer can be provided to the optical laminate by attaching one surface on the conductive layer 13 side to another optical member (for example, an image element (for example, a liquid crystal panel, an organic EL panel), an optical film (for example, a retardation film), a polarizing plate, or the like), and then peeling off the temporary support 11 to transfer the laminate a composed of the liquid crystal layer 12 and the conductive layer 13. In the conventional art, the conductive layer is provided on the optical laminate including the substrate in a state of being formed on the substrate, but when the conductive film for transfer of the present invention is used, an optical laminate including no substrate necessary for forming the conductive layer can be formed. In general, the substrate is rigid because it functions as a support, but an optical laminate including no such substrate is excellent in bendability. In addition, the optical laminate not including the substrate exerts less load on the conductive layer when bent, and the conductive layer is less likely to be damaged.

Further, when the transfer conductive film of the present invention is used, an optical laminate including an optical member which is easily damaged in a process (for example, a heat treatment) for forming a conductive layer can also exclude a rigid substrate. For example, although a polarizing plate is damaged when a film including the polarizing plate is directly subjected to a treatment such as sputtering, an optical laminate can be formed without damaging the polarizing plate when the conductive film for transfer of the present invention is used.

A-1. conductive layer

In 1 embodiment, the conductive layer can function as an electrode of a touch device.

Preferably, the conductive layer is made of a metal oxide. Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, indium-zinc composite oxide, and the like. Among them, indium-tin composite oxide (ITO) is preferable. The conductive layer may be a layer containing a conductive polymer, a conductive filler, metal nanowires, and/or a metal mesh.

The conductive layer preferably has light-transmitting properties. The total light transmittance of the conductive layer is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. By forming the conductive layer with the metal oxide, a conductive layer with high light transmittance can be formed.

The surface resistance value of the conductive layer is preferably 0.1 Ω/□ to 1000 Ω/□, more preferably 0.5 Ω/□ to 500 Ω/□, and particularly preferably 1 Ω/□ to 250 Ω/□.

In 1 embodiment, the conductive layer is formed directly on the liquid crystal layer. Specific examples of the present embodiment include a method in which a metal oxide layer is formed on the liquid crystal layer by any suitable film formation method (for example, a vacuum deposition method, a sputtering method, a CVD method, an ion plating method, a spraying method, or the like) to obtain a conductive layer. The metal oxide layer may be used as a conductive layer as it is, or may be further heated to crystallize the metal oxide. The temperature during the heating is, for example, 120 to 200 ℃.

The thickness of the conductive layer is preferably 50nm or less, and more preferably 40nm or less. In the case where the amount is within such a range, a conductive layer having excellent light transmittance can be obtained. The lower limit of the thickness of the conductive layer is preferably 1nm, and more preferably 5 nm.

The conductive layer may be patterned. As the method of patterning, any appropriate method may be adopted depending on the form of the conductive layer. For example, patterning can be performed by an etching method, a laser method, or the like. The shape of the pattern of the conductive layer may be any suitable shape according to the application. Examples of the pattern include those described in Japanese patent publication Nos. 2011-511357, 2010-164938, 2008-310550, 2003-511799 and 2010-541109.

A-2. liquid crystal layer

The liquid crystal layer comprises any suitable liquid crystal compound. The transfer conductive film of the present invention is configured such that a conductive layer is formed on a liquid crystal layer, and the liquid crystal layer is disposed between the conductive layer and a temporary support, whereby a laminate a composed of the conductive layer and the liquid crystal layer can be transferred to another optical member. It is one of the achievements of the present invention that both the liquid crystal layer and the conductive layer having predetermined functions can be introduced into the optical laminate by excluding the rigid substrate.

In 1 embodiment, the refractive index characteristic of the liquid crystal layer is expressed by nz > nx ≧ ny. By providing such a liquid crystal layer, the laminate a can be produced as a laminate having an optical function.

The retardation Rth (550) in the thickness direction of the liquid crystal layer is preferably-260 nm to-10 nm, more preferably-230 nm to-15 nm, and still more preferably-215 nm to-20 nm.

In 1 embodiment, the refractive index of the liquid crystal layer is expressed by nx ═ ny. Here, "nx ═ ny" includes not only a case where nx and ny are exactly equal but also a case where nx and ny are substantially equal. Specifically, it means that Re (550) is less than 10 nm. In another embodiment, the liquid crystal layer has a refractive index exhibiting a relationship of nx > ny. In this case, the in-plane retardation Re (550) of the liquid crystal layer is preferably 10nm to 150nm, more preferably 10nm to 80 nm.

The liquid crystal layer is fixed in a vertical orientation. The liquid crystal material (liquid crystal compound) capable of vertical alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the liquid crystal layer include the liquid crystal compounds and the methods for forming the same described in [0020] to [0042] of Japanese patent laid-open publication No. 2002-333642.

The thickness of the liquid crystal layer is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and still more preferably 0.2 to 3 μm. Within such a range, a desired optical laminate can be obtained, and a transfer conductive film having excellent releasability of the laminate a can be obtained.

The total light transmittance of the liquid crystal layer is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more.

A-3. temporary support

As the resin constituting the temporary support, any suitable resin may be used as long as the effects of the present invention can be obtained. Examples of the resin constituting the temporary support include a cycloolefin resin, a polyimide resin, a polyvinylidene chloride resin, a polyvinyl chloride resin, a polyethylene terephthalate resin, and a polyethylene naphthalate resin.

The thickness of the temporary support is preferably 8 to 500. mu.m, more preferably 50 to 250. mu.m.

The adhesion strength of the temporary support to the liquid crystal layer at 23 ℃ is preferably 0.01N/25mm to 1N/25mm, more preferably 0.01N/25mm to 0.7N/25 mm. Within such a range, a transfer conductive thin film that can be easily transferred to the laminate a can be obtained. The adhesion was determined by the method according to JIS Z0237: the term "2000" as measured means the adhesive force measured by peeling the temporary support from the produced conductive transfer film at a tensile rate of 300 mm/min and a peel angle of 180 °.

The temporary support may be subjected to various surface treatments as required. For the surface treatment, any appropriate method may be employed depending on the purpose. In the 1 embodiment, a release layer may be provided on one surface of the temporary support on the liquid crystal layer side in order to facilitate peeling from the liquid crystal layer. The release layer may be formed of any appropriate material as long as the above adhesive force is exhibited, and may be formed by a known release treatment (for example, coating of a silicone release agent). In addition, an alignment layer may be provided in order to improve alignment of the liquid crystal layer.

B. Optical laminate

The optical laminate of the present invention includes a laminate a (a laminate including a liquid crystal layer and a conductive layer) transferred from the transfer conductive film. In one embodiment, a touch device including the optical layered body is provided. In the touch device, the conductive layer functions as an electrode. The touch device is also useful in that it has excellent flexibility and the conductive layer is not easily damaged even when bent.

Fig. 2 is a schematic cross-sectional view of an optical stack according to 1 embodiment of the present invention. The optical laminate 100 includes, in order: an optical member 20, a conductive layer 13, and a liquid crystal layer 12. In embodiment 1, the optical member 20 and the conductive layer 13 are laminated via the adhesive layer 30, and the adhesive layer 30 is in contact with the optical member 20 and the conductive layer 13.

In the optical laminate 100, the laminate a composed of the conductive layer 13 and the liquid crystal layer 12 is a laminate transferred from the transfer conductive film. The conductive layer 13 is laminated directly (i.e., without an adhesive layer or the like) to the liquid crystal layer 12.

Fig. 3 is a schematic cross-sectional view of an optical stack according to yet another embodiment of the present invention. The optical laminate 200 includes, in order: an optical member 20, a conductive layer 13, a liquid crystal layer 12, and another optical member 40. In 1 embodiment, the optical member 20 and the conductive layer 13 are laminated via the adhesive layer 30, and the adhesive layer 30 is in contact with the optical member 20 and the conductive layer 13. In addition, in 1 embodiment, the liquid crystal layer 12 and the other optical member 40 are laminated via the adhesive layer 30, and the adhesive layer 30 is in contact with the liquid crystal layer 12 and the other optical member 40.

Examples of the optical member 20 and the other optical member 40 include a picture element (e.g., a liquid crystal panel and an organic EL panel), an optical film (e.g., a retardation film), a polarizing plate, and a circularly polarizing plate.

In 1 embodiment, a polarizing plate or a circularly polarizing plate is used as the optical member 20. According to another embodiment, as the other optical member 40, a polarizing plate or a circular polarizing plate is used. When the optical laminate is applied to an image display device (for example, a touch device), the conductive layer may be disposed so as to be on the visible side with respect to the polarizing plate or the circularly polarizing plate, or the conductive layer may be disposed so as to be on the inner side (on the opposite side to the visible side) with respect to the polarizing plate or the circularly polarizing plate.

B-1. polarizing plate

In 1 embodiment, an optical laminate using a polarizing plate as an optical member or another optical member, that is, an optical laminate comprising a polarizing plate, a conductive layer, and a liquid crystal layer in this order; or an optical laminate comprising a conductive layer, a liquid crystal layer, and a polarizing plate in this order. Conventionally, when a conductive layer is formed directly on a film including a polarizing plate by a conductive layer applying treatment such as sputtering, a problem such as damage to the polarizing plate occurs in the conductive layer applying treatment, and when the conductive film for transfer of the present invention is used, an optical laminate can be formed without causing damage to the polarizing plate. An example of the polarizing plate used in the optical laminate will be described below.

The polarizing plate includes a polarizer. The polarizing plate preferably further includes a protective film on one side or both sides of the polarizer.

The thickness of the polarizer is not particularly limited, and an appropriate thickness may be used according to the purpose. The thickness is typically about 1 μm to 80 μm. In 1 embodiment, a thin polarizer is used, and the thickness of the polarizer is preferably 20 μm or less, more preferably 15 μm or less, further preferably 10 μm or less, and particularly preferably 6 μm or less. By using such a thin polarizer, a thin optical laminate can be obtained.

The polarizing element preferably exhibits dichroism of absorption at any wavelength of 380nm to 780 nm. The monomer transmittance of the polarizer is preferably 40.0% or more, more preferably 41.0% or more, further preferably 42.0% or more, and particularly preferably 43.0% or more. The degree of polarization of the polarizer is preferably 99.8% or more, more preferably 99.9% or more, and still more preferably 99.95% or more.

Preferably, the polarizer is an iodine-based polarizer. More specifically, the polarizer may be formed of a polyvinyl alcohol resin film containing iodine (hereinafter referred to as "PVA resin").

As the PVA resin forming the PVA resin film, any suitable resin may be used. For example, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are listed. 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 resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The degree of saponification can be determined in accordance with JIS K6726-. By using the PVA-based resin having such a saponification degree, a polarizing plate having excellent durability can be obtained. If the degree of saponification is too high, gelation may occur.

The average polymerization degree of the PVA-based resin can be appropriately selected according to the purpose. The average polymerization degree is usually 1000 to 10000, preferably 1200 to 5000, and more preferably 1500 to 4500. The average degree of polymerization can be determined in accordance with JIS K6726-.

Examples of the method for producing the polarizer include a method (I) in which a PVA-based resin film is stretched and dyed alone; and (II) a method of stretching and dyeing the laminate (i) having the resin base material and the polyvinyl alcohol resin layer. The method (I) is a method known in the art, and therefore, a detailed description thereof will be omitted. The production method (II) preferably includes the steps of: and (ii) stretching and dyeing a laminate (i) comprising a resin base and a polyvinyl alcohol resin layer formed on one side of the resin base to produce a polarizing plate on the resin base. The laminate (i) can be formed by applying a coating solution containing a polyvinyl alcohol resin on a resin base material and drying the coating solution. The laminate (i) may be formed by transferring a polyvinyl alcohol resin film onto a resin substrate. Details of the above-mentioned production process (II) are described in, for example, Japanese patent laid-open No. 2012 and 73580, which are incorporated herein by reference.

As the protective film, any appropriate resin film can be used. Examples of the material for forming the protective film include polyester resins such as polyethylene terephthalate (PET), cellulose resins such as Triacetylcellulose (TAC), cycloolefin resins such as norbornene resins, olefin resins such as polyethylene and polypropylene, and (meth) acrylic resins. Among them, polyethylene terephthalate (PET) is preferable.

In 1 embodiment, a (meth) acrylic resin having a glutarimide structure is used as the (meth) acrylic resin.

The protective film and the polarizer are laminated via an arbitrary appropriate adhesive layer. The resin substrate used for producing the polarizer may be peeled off before or after the protective film and the polarizer are laminated.

The thickness of the protective film is preferably 5 to 55 μm, more preferably 10 to 50 μm, and still more preferably 15 to 45 μm.

B-2. circular polarizing plate

Fig. 4 is a schematic cross-sectional view of an optical stack according to 1 embodiment of the present invention. The optical laminate 110 includes a circularly polarizing plate 21 as an optical member. The circularly polarizing plate 21 includes a polarizer 1 and a retardation layer 2. In the 1 embodiment, the polarizer 1 is preferably disposed on the side of the retardation layer 2 opposite to the laminate a (i.e., conductive layer). The circularly polarizing plate 21 and the laminate a are laminated via the adhesive layer 30, and the adhesive layer 30 is in contact with the retardation layer 2 and the conductive layer 13. In another embodiment, a circularly polarizing plate is used as the other optical member, and an optical laminate is provided which includes the optical member, a conductive layer, a liquid crystal layer, and a circularly polarizing plate (retardation layer/polarizer) in this order. In this embodiment, the polarizing material is also preferably disposed on the side of the retardation layer opposite to the laminate a (i.e., the liquid crystal layer).

In 1 embodiment, the circularly polarizing plate further includes a protective film (not shown) on the surface opposite to the retardation layer of the polarizer. The circularly polarizing plate may further include another protective film (also referred to as an inner protective film: not shown) between the polarizer and the retardation layer. As the polarizer and the protective film, the polarizer and the protective film described in the above item B-1 can be used.

The retardation layer can function as a λ/4 plate. The in-plane retardation Re (550) of such a retardation layer is preferably 120nm to 160nm, more preferably 135nm to 155 nm. The phase difference layer typically has a refractive index ellipsoid having nx > ny ≧ nz.

The Rth (550) of the retardation layer is preferably 120nm to 300nm, more preferably 135nm to 260 nm.

The Nz coefficient of the retardation layer is, for example, 0.9 to 2, preferably 1 to 1.8, and more preferably 1 to 1.7.

The polarizer and the retardation layer are laminated such that the absorption axis of the polarizer and the slow axis of the retardation layer form a predetermined angle. The angle formed by the absorption axis of the polarizer and the slow axis of the retardation layer is preferably 35 ° to 55 °, more preferably 38 ° to 52 °, still more preferably 40 ° to 50 °, still more preferably 42 ° to 48 °, and particularly preferably 44 ° to 46 °. When the angle is within such a range, a desired circular polarization function can be realized. In the present specification, when an angle is referred to, the angle includes both clockwise and counterclockwise angles unless otherwise specified.

The thickness of the retardation layer can be set so as to function optimally as a λ/4 plate. In other words, the thickness may be set so as to obtain a desired in-plane retardation. Specifically, the thickness of the retardation layer is preferably 10 to 80 μm, more preferably 10 to 60 μm, and most preferably 30 to 50 μm.

The phase difference layer may exhibit reverse dispersion wavelength characteristics in which the phase difference value increases according to the wavelength of the measurement light, may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases according to the wavelength of the measurement light, and may also exhibit flat wavelength dispersion characteristics in which the phase difference value hardly changes according to the wavelength of the measurement light.

The λ/4 plate is preferably a stretched film of a polymer film. Specifically, by appropriately selecting the type of polymer and the stretching treatment (for example, stretching method, stretching temperature, stretching ratio, and stretching direction), a λ/4 plate can be obtained.

As the resin for forming the polymer film, any appropriate resin is used. Specific examples thereof include resins constituting a positive birefringent film, such as cycloolefin resins such as polynorbornene, polycarbonate resins, cellulose resins, polyvinyl alcohol resins, and polysulfone resins. Among them, norbornene-based resins and polycarbonate-based resins are preferable. The details of the resin for forming a polymer film are described in, for example, jp 2014-010291 a. This description is incorporated herein by reference.

Various products are commercially available as the above polynorbornene. Specific examples thereof include trade names "ZEONEX" and "ZEONOR" manufactured by zeon corporation, JSR, TICONA, TOPAS, and adel, mitsui chemical co.

Examples of the stretching method include transverse uniaxial stretching, fixed-end biaxial stretching, and sequential biaxial stretching. Specific examples of the fixed-end biaxial stretching include a method in which a polymer film is stretched in the short-side direction (transverse direction) while being moved in the longitudinal direction. The process may be apparently transverse uniaxial stretching. In addition, oblique stretching may also be employed. By oblique stretching, a stretched film in the form of a strip having an orientation axis (slow axis) at a predetermined angle with respect to the width direction can be obtained.

The thickness of the stretched film is typically 5 to 80 μm, preferably 15 to 60 μm, and more preferably 25 to 45 μm.

B-3 adhesive layer

The adhesive layer is formed of any suitable adhesive. In 1 embodiment, the adhesive contains an adhesive resin, and examples of the resin include acrylic resins, acrylic urethane resins, silicone resins, and the like. Among them, acrylic adhesives containing acrylic resins are preferable.

The adhesive may further contain any suitable additive as required. Examples of the additives include a crosslinking agent, an adhesion imparting agent, a plasticizer, a pigment, a dye, a filler, an anti-aging agent, a conductive material, an ultraviolet absorber, a light stabilizer, a release controlling agent, a softening agent, a surfactant, a flame retardant, and an antioxidant. Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, peroxide-based crosslinking agents, melamine-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents.

The thickness of the pressure-sensitive adhesive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm.

B-4. other layers

The optical laminate may be provided with any appropriate other layer as needed. Examples of the other layer include a hard coat layer, an antiglare layer, an antireflection layer, and a color filter layer.

C. Method for manufacturing optical laminate

The method for producing an optical laminate of the present invention includes transferring a laminate a including a liquid crystal layer and a conductive layer from the transfer conductive film to an optical member. In one embodiment, in the manufacturing method, the conductive layer and the optical member are laminated via an adhesive layer. The conductive film for transfer, the optical member and the pressure-sensitive adhesive layer described in the above items a and B can be used as the conductive film for transfer, the optical member and the pressure-sensitive adhesive layer.

After the laminate a is transferred to the optical member, another optical member may be laminated on the liquid crystal layer of the laminate a via an adhesive layer.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples at all. The thickness was measured using a digital Cordless (digital core Type) "DG-205" of a PEACOCK precision measuring instrument manufactured by kawasaki corporation.

[ example 1]

A liquid crystal layer was formed on a polyethylene terephthalate film (PANAC CO., LTD., product name "PANA-PEEL", thickness: 38 μm) subjected to a peeling treatment as a temporary support by the following method.

A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side chain type liquid crystal polymer represented by the following chemical formula (I) (in the formula, numerals 65 and 35 represent the mol% of a monomer unit, and for convenience are represented by a block polymer, weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (product name: Paliocol LC242 manufactured by BASF Co., Ltd.), and 5 parts by weight of a photopolymerization initiator (product name: Irgacure 907 manufactured by Ciba specialty Chemicals Inc.) in 200 parts by weight of cyclopentanone. Then, the coating liquid was applied to a release-treated surface of a PET film (temporary support) by a bar coater, and then heated and dried at 80 ℃ for 4 minutes to align the liquid crystal. The liquid crystal layer was irradiated with ultraviolet rays and cured, thereby forming a cured liquid crystal layer (thickness: 0.58 μm) on the PET film (temporary support). The in-plane retardation Re (550) of the liquid crystal layer was 0nm, and the retardation Rth (550) in the thickness direction was-71 nm (nx: 1.5326, ny: 1.5326, nz: 1.6550), and the liquid crystal layer exhibited refractive index characteristics of nz > nx ═ ny.

Next, the laminate composed of the temporary support and the liquid crystal layer was put into a sputtering apparatus, and an amorphous indium-tin oxide layer having a thickness of 30nm was formed on the surface of the liquid crystal layer. Then, the indium-tin oxide was converted from amorphous to crystalline by a heat treatment at 130 ℃ for 90 minutes, thereby obtaining a conductive thin film for transfer (conductive layer/liquid crystal layer/temporary support).

Using the obtained transfer conductive film, a laminate a composed of a conductive layer and a liquid crystal layer was transferred from a temporary support to a PET film (thickness: 23 μm) via a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive, and the temporary support was peeled off to obtain a sample for evaluation of bending resistance (liquid crystal layer/conductive layer/pressure-sensitive adhesive layer/PET substrate).

Comparative example 1

A transparent dielectric layer having a thickness of 35nm (refractive index: 1.54) was formed by applying a thermosetting resin containing a melamine resin, an alkyd resin, and an organosilane condensate (melamine resin: alkyd resin: organosilane condensate (weight ratio): 2: 1) on one surface of a polyethylene terephthalate (PET) film (manufactured by mitsubishi chemical corporation, trade name "diafil", thickness: 23 μm) and curing the resin.

Thereafter, the PET film with the transparent dielectric layer was fed into a take-up sputtering apparatus, and an indium-tin oxide layer (thickness: 30nm) was formed as a conductive layer on the surface of the transparent dielectric layer. For the sputtering treatment, in an atmosphere of 0.4Pa containing 98% of argon and 2% of oxygen, a sintered body containing 97% by weight of indium oxide to 3% by weight of tin oxide was used.

The laminate obtained as described above was bonded to a PET film (thickness: 23 μm) via an adhesive layer containing an acrylic adhesive to obtain a sample for evaluation of bending resistance (PET substrate/dielectric layer/conductive layer/adhesive layer/PET substrate).

Comparative example 2

A coating composition A was prepared which contained 0.16 parts by weight of a plurality of monodisperse particles having an average particle diameter of 1.8 μm (trade name "MX 180-TAN" manufactured by Soken chemical Co., Ltd., refractive index: 1.495), 100 parts by weight of a binder resin (trade name "UNIDIC" manufactured by DIC Co., Ltd., refractive index: 1.51), and a solvent (ethyl acetate). Then, the coating composition a was applied to a strip-shaped substrate film (product name "ZEONOR", thickness manufactured by zeon corporation, japan) using a gravure coater so that the thickness of the flat portion after drying became 1.0 μmDegree: 40 μm) was heated at 80 ℃ to dry the coating film. Thereafter, the accumulated light amount was irradiated with 250mJ/cm by a high-pressure mercury lamp²Thereby forming an anti-blocking layer.

Next, a coating composition B was prepared by diluting a binder resin (product name "unicic" manufactured by DIC corporation, refractive index 1.51) with ethyl acetate. The coating composition B was applied to the surface of the strip-like base film opposite to the antiblocking layer using a gravure coater so that the thickness of the flat portion after drying became 1.0 μm, and the coating film was dried by heating at 80 ℃. Thereafter, the accumulated light amount was irradiated with 250mJ/cm by a high-pressure mercury lamp²Thereby forming a hard coating layer.

Next, a refractive index adjuster (product name "opstar z 7412" manufactured by JSR corporation, an organic-inorganic composite material containing zirconium oxide particles having a median particle diameter of 40nm as an inorganic component and having a refractive index of 1.62) was applied to the surface of the hard coat layer using a gravure coater, and the resultant was heated at 60 ℃. Thereafter, the accumulated light amount was irradiated with 250mJ/cm by a high-pressure mercury lamp²By curing the cured layer with ultraviolet rays, an optical adjustment layer having a thickness of 115nm and a refractive index of 1.62 was formed.

Thereafter, the strip-shaped substrate film having the anti-blocking layer, the hard coat layer, and the optical adjustment layer laminate was put into a take-up sputtering apparatus, and an indium-tin oxide layer (thickness: 30nm) was formed as a conductive layer on the surface of the COP substrate. For the sputtering treatment, in an atmosphere of 0.4Pa containing 98% of argon and 2% of oxygen, a sintered body containing 97% by weight of indium oxide to 3% by weight of tin oxide was used.

The laminate obtained as described above was bonded to a PET film (thickness: 23 μm) via an adhesive layer containing an acrylic adhesive to obtain a sample for evaluation of bending resistance (COP substrate/stripe-shaped substrate film with an optical adjustment layer/conductive layer/adhesive layer/PET substrate).

< evaluation 1>

(bending resistance test)

The evaluation samples obtained in example 1, comparative example 1, and comparative example 2 were subjected to a bending resistance test. The results are shown in Table 1. The bending resistance test method is as follows.

The resistance value change after the bending test of each sample for evaluation was measured using an automatic bending tester and a resistance value tester manufactured by YUASA SYSTEM co.

For the bending test, the test diameter is defined as the diameter

The bending is performed so that the PET substrate side bonded via the adhesive becomes the outer curved surface side.

As a result of the above test, in example 1, no change in the resistance value was observed even after 20 ten thousand times of bending, whereas in comparative examples 1 and 2, it was confirmed that the resistance value was greatly changed by bending less than the number of times. The results are graphically shown in fig. 5.

[ example 2]

(preparation of polarizing Member)

After dyeing a polyvinyl alcohol film in a form of a strip in an aqueous solution containing iodine, it was uniaxially stretched 6 times between rolls having different speed ratios in an aqueous solution containing boric acid to obtain a polarizer in a form of a strip having an absorption axis in the longitudinal direction (thickness: 12 μm). The strip-shaped polarizer is stretched and then wound to form a wound body.

(preparation of protective film)

As the protective film, a strip-shaped cellulose triacetate film (thickness 40 μm, manufactured by KONICA MINOLTA, INC., trade name: KC4UYW) was used. The protective film is prepared in the form of a roll. The in-plane retardation Re (550) of the protective film was 5nm, and the retardation Rth (550) in the thickness direction was 45 nm.

(preparation of retardation film)

A commercially available retardation film (product name "PURE-ACE WR" manufactured by Diko K.K.; thickness: 51 μm) showing wavelength dependence of inverse dispersion was used. The retardation film had an in-plane retardation Re (550) of 147nm and an Re (450)/Re (550) of 0.89.

(production of circular polarizing plate)

The polarizing plate, the protective film and the retardation film were cut into pieces of 200mm × 300 mm. The polarizer and the protective film are bonded to each other with a polyvinyl alcohol adhesive. A circularly polarizing plate (thickness: 105 μm) having a structure of a protective film/polarizer/retardation layer was produced by laminating a polarizer/protective film laminate and a retardation film via an acrylic pressure-sensitive adhesive layer so that the polarizer and the retardation film were adjacent to each other. The retardation film was disposed so that the slow axis of the retardation film and the absorption axis of the polarizer formed an angle of 45 ° at the time of lamination.

(production of optical layered body)

A conductive thin film for transfer was obtained in the same manner as in example 1. Using this transfer conductive film, a laminate a composed of a conductive layer and a liquid crystal layer was transferred from a temporary support to the retardation film side of the circularly polarizing plate via a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive, to obtain an optical laminate (circularly polarizing plate (protective film/polarizing material/retardation layer)/pressure-sensitive adhesive layer/conductive layer/liquid crystal layer). The total thickness of the optical laminate was 110 μm, and the optical laminate was thin and bendable without damaging the respective layers.

Further, the liquid crystal layer side of the optical laminate was attached to an organic EL panel, and the optical characteristics of the optical laminate when the panel was not lit were confirmed. In this configuration, it was confirmed that the conductive layer laminated on the liquid crystal layer can enjoy the antireflection effect of the circularly polarizing plate, and can realize an excellent black tone.

Comparative example 3

A laminate comprising a PET substrate, a dielectric layer, and a conductive layer in this order was obtained in the same manner as in comparative example 1. The PET substrate side of the laminate was attached to the same protective film for a circularly polarizing plate as in example 2 via an adhesive layer containing an acrylic adhesive. Further, the liquid crystal coating solution prepared in example 1 was applied to the retardation film side of the circularly polarizing plate in the same manner as in example 1 to form a liquid crystal layer, thereby obtaining an optical laminate (conductive layer/dielectric layer/PET substrate/circularly polarizing plate (protective film/polarizer/retardation layer)/liquid crystal layer). The total thickness of the optical laminate was 135. mu.m.

Further, the liquid crystal layer side of the optical laminate was attached to an organic EL panel, and the antireflection ability of the optical laminate was confirmed. The optical laminate was remarkably confirmed to reflect light by the conductive layer.

[ reference example 1]

In the same manner as in comparative example 2, a laminate was obtained which successively included a COP substrate, a stripe-shaped substrate film with an optical adjustment layer, and a conductive layer.

The liquid crystal coating liquid prepared in example 1 was applied to the retardation film side of the circularly polarizing plate similar to example 2 in the same manner as in example 1 to form a liquid crystal layer.

Next, the conductive layer side of the laminate was attached to the liquid crystal layer via an adhesive layer containing an acrylic adhesive, to obtain an optical laminate (circularly polarizing plate (protective film/polarizing plate/retardation layer)/liquid crystal layer/conductive layer/stripe substrate film with optical adjustment layer/COP substrate). The total thickness of the optical laminate was 150. mu.m.

The liquid crystal layer side of the optical laminate was attached to an organic EL panel, and the antireflection ability of the optical laminate was confirmed. The optical laminate exhibits antireflection performance.

Description of the reference numerals

10 transfer conductive film

11 temporary support

12 liquid crystal layer

13 conductive layer

20 optical member

Claims

1. A conductive film for transfer printing, comprising in order: a temporary support, a liquid crystal layer provided so as to be peelable from the temporary support, and a conductive layer.

2. The transfer conductive film according to claim 1, wherein the conductive layer is directly laminated on the liquid crystal layer.

3. The transfer conductive film according to claim 1, wherein the refractive index characteristic of the liquid crystal layer shows a relationship of nz > nx ≧ ny.

4. The transfer conductive film according to claim 1, wherein the liquid crystal layer has a thickness of 0.1 to 10 μm.

5. The transfer conductive film according to claim 1, wherein the conductive layer is formed of a metal oxide.

6. The transfer conductive film according to claim 1, wherein the conductive layer is patterned.

7. An optical laminate comprising, in order: an optical member; an adhesive layer; the conductive layer of claim 1, 5 or 6; and a liquid crystal layer according to claim 1, 3 or 4,

the conductive layer is directly laminated on the liquid crystal layer.

8. The optical stack of claim 7, wherein the optical member is a polarizer.

9. The optical stack according to claim 7, wherein the optical member is a circularly polarizing plate,

the circularly polarizing plate includes: a polarizing element, and a retardation layer functioning as a lambda/4 plate,

the polarizer is disposed on the opposite side of the retardation layer from the conductive layer.

10. The optical laminate according to claim 7, further comprising another optical member on a side of the liquid crystal layer opposite to the conductive layer.

11. The optical stack according to claim 10, wherein the further optical component is a circular polarizer,

the polarizer is disposed on a side of the retardation layer opposite to the liquid crystal layer.

12. A touch device comprising the optical laminate according to claim 7.

13. A method of manufacturing an optical stack, comprising: transferring the laminate A comprising the liquid crystal layer and the conductive layer from the transfer conductive film according to claim 1 to an optical member.