TWI881140B - Polarizing plate with pressure-sensitive adhesive layer - Google Patents

Abstract

An object of the present invention is to provide a polarizing plate with a pressure-sensitive adhesive layer that suppresses iodine loss even in a high-temperature and high-humidity environment.

The polarizing plate with the pressure-sensitive adhesive layer, which comprises a polarizer, and a protective film arranged on one side of the polarizer via an adhesive layer, and comprises a second pressure-sensitive adhesive layer arranged on the other side of the polarizer, a functional layer, and a first pressure-sensitive adhesive layer in this order, wherein the functional layer is a single layer of the liquid crystal cured layer alone, or two or more layers selected from the group of the liquid crystal cured layer, the oriented layer and the bonded layer, the polarizer is a film in which iodine is adsorbed on a hydrophilic polymer film, the permeability of the first pressure-sensitive adhesive layer at 40 ℃, 90%R. H. relative humidity is 500 g / (m²．day) or less.

Description

Polarizing plate with adhesive layer

The present invention relates to a polarizing plate with a pressure sensitive adhesive layer, and more particularly to an image display device containing the polarizing plate with the pressure sensitive adhesive layer.

Patent document 1 has proposed a polarizing plate with an adhesive layer in which a polarizing protective film is laminated on one side of the polarizing element through a bonding agent layer, and an adhesive layer is laminated on the other side.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2012-247574

The purpose of the present invention is to provide a polarizing plate with an adhesive layer that can inhibit iodine release even in a high temperature and high humidity environment.

The present invention provides the following polarizing plate and image display with adhesive layer.

[1] A polarizing plate with an adhesive layer, comprising a polarizing element, a protective film disposed on one side of the polarizing element through an adhesive layer, and a second adhesive layer, a functional layer and a first adhesive layer in order from the polarizing element side on the other side of the polarizing element, wherein:

The aforementioned functional layer is a single layer of a single liquid crystal curing layer, or a plurality of layers of two or more selected from the group of a liquid crystal curing layer, an alignment layer, and a bonding layer.

The aforementioned polarizer is a film in which iodine is adsorbed in a hydrophilic polymer film.

The moisture permeability of the first adhesive layer is less than 500g/(m ² ·day) at a temperature of 40°C and a relative humidity of 90%RH.

[2] A polarizing plate with an adhesive layer as described in [1], wherein the first and second adhesive layers are adhesive layers formed of a rubber-based adhesive composition containing polyisobutylene and a dehydrogenation-type photopolymerization initiator.

[3] A polarizing plate with an adhesive layer as described in [1], wherein the first and second adhesive layers are adhesive layers containing a polyolefin resin.

[4] A polarizing plate with an adhesive layer as described in [3], wherein the polyolefin resin comprises an amorphous polypropylene resin.

[5] A polarizing plate with an adhesive layer as described in any one of [1] to [4], wherein the thickness of the first adhesive layer is greater than 10 μm.

[6] A polarizing plate with an adhesive layer as described in any one of [1] to [5], wherein the protective film is a film composed of a cyclic polyolefin resin.

[7] A polarizing plate with an adhesive layer as described in any one of [1] to [6], wherein the functional layer comprises a first liquid crystal curing layer and a second liquid crystal curing layer.

[8] A multilayer body for a flexible image display, comprising a polarizing plate with an adhesive layer as described in any one of [1] to [7], and a front panel or a touch sensor.

[9] An image display device having a polarizing plate with an adhesive layer as described in any one of [1] to [7].

The present invention can provide a polarizing plate with an adhesive layer that can inhibit iodine release even in a high temperature and high humidity environment.

10: Polarizer

11: Protective film

12: Next is the agent layer

13: 1st adhesive layer

14: Second adhesive layer

15: Functional layer

50: The end of the polarizing plate with adhesive layer attached

51: Iodine release area

52: Non-iodine release area

100: Polarizing plate with adhesive layer

T: penetration axis direction

FIG1 is a schematic diagram showing an example of a polarizing plate with an adhesive layer of the present invention.

Figure 2 is a schematic diagram showing the sample setting method for iodine release evaluation.

FIG3 is a diagram showing an optical microscope observation image of the polarizing plate with an adhesive layer obtained in Example 1.

FIG4 is a graph showing the observation image of the polarizing plate with an adhesive layer obtained in Example 1 converted into black and white 256-color data.

The following is a description of the implementation of the present invention with reference to the diagrams, but the present invention is not limited to the scope of the following implementation. In all the following diagrams, the proportions of the components are appropriately adjusted for easy understanding, and the proportions of the components shown in the diagrams are not necessarily consistent with the proportions of the actual components.

<Polarizing plate with adhesive layer>

The polarizing plate with adhesive layer has a polarizer, a protective film arranged on one side of the polarizer through an adhesive layer, and a second adhesive layer, a functional layer, and a first adhesive layer arranged in order from the polarizer side on the other side of the polarizer. An example of the layer structure of the polarizing plate with adhesive layer is shown in FIG1. FIG1 is a schematic cross-sectional view of an example of the polarizing plate with adhesive layer. The polarizing plate with adhesive layer 100 shown in FIG1 has a protective film 11, an adhesive layer 12, a polarizer 10, a second adhesive layer 14, a functional layer 15, and a first adhesive layer 13 in order.

The polarizing plate 100 with an adhesive layer is preferably composed of only a protective film 11, an adhesive layer 12, a polarizer 10, a second adhesive layer 14, a functional layer 15, and a first adhesive layer 13. The polarizing plate 100 with an adhesive layer is preferably laminated with the protective film 11 on one side of the polarizer 10 only through the adhesive layer 12. The polarizing plate 100 with an adhesive layer is preferably laminated with the second adhesive layer 14 directly on the side opposite to the adhesive layer 12 side of the polarizer 10.

The thickness of the polarizing plate 100 with an adhesive layer varies depending on the required function and the purpose of the polarizing plate 100 with an adhesive layer, and there is no particular limitation, but it can be, for example, 10 μm or more, or 20 μm or more, or 200 μm or less, or 150 μm or less, 120 μm or less, 100 μm or less, 80 μm or less, or 70 μm or less.

[Polarizer]

The polarizer 10 has the following properties: absorbing linear polarization with a vibration plane parallel to its absorption axis, and transmitting linear polarization with a vibration plane perpendicular to the absorption axis (and parallel to the transmission axis). The polarizer 10 is a film in which iodine is adsorbed in a hydrophilic polymer film. The polarizer 10 can be manufactured by, for example, the following steps: a step of uniaxially extending the hydrophilic polymer film, a step of dyeing the hydrophilic polymer film with iodine to adsorb the iodine, a step of treating the hydrophilic polymer film adsorbed with iodine with a boric acid aqueous solution, and a step of washing with water after the boric acid aqueous solution treatment.

Examples of hydrophilic polymer membranes include polyvinyl alcohol resin membranes. Polyvinyl alcohol resin membranes can be obtained by saponifying polyvinyl acetate resins. In addition to homopolymers of vinyl acetate, polyvinyl acetate can also use copolymers of vinyl acetate and other monomers that can be copolymerized with it. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated sulfonate compounds, and (meth)acrylamide compounds having an ammonium group. In this specification, "(meth)acrylic acid" refers to at least one selected from acrylic acid and methacrylic acid. The same applies to "(meth)acrylate" and the like.

The saponification degree of polyvinyl alcohol resin is usually about 85 mol% to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin can be modified, and polyvinyl formal, polyvinyl acetaldehyde, etc. modified with aldehydes can also be used. The polymerization degree of polyvinyl alcohol resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

The polarizer 10 is a structure in which iodine is adsorbed and oriented and the boron content is 5.5 mass% or less, preferably 5.0 mass% or less, and more preferably 4.5 mass% or less, thereby suppressing shrinkage caused by heating. The boron content is preferably 0.5 mass% or more, more preferably 1 mass% or more, and can also be 2 mass% or more. By having a boron content of 0.5 mass% or more, iodine can be stably maintained and color loss can be expected to be suppressed.

The thickness of the polarizer 10 is usually less than 30 μm, preferably less than 15 μm, more preferably less than 13 μm, and even more preferably less than 10 μm. The thickness of the polarizer 10 is usually more than 2 μm, preferably more than 3 μm, and can also be more than 5 μm, for example.

[Protective film]

The protective film 11 can be arranged on one side of the polarizer 10 and has the function of protecting the polarizer 10. The protective film 11 is an optically transparent thermoplastic resin and can be made into a coating layer or film composed of, for example, cyclic polyolefin resins; cellulose acetate resins including triacetyl cellulose, diacetyl cellulose and other resins; polyester resins formed by resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins; (meth) acrylic resins; polypropylene resins, and a mixture of one or more of these resins.

A hard coating layer may also be formed on the protective film 11. The hard coating layer may be formed on one side of the protective film 11 or on both sides. By providing the hard coating layer, a protective film 11 with improved hardness and scratch resistance may be made. The hard coating layer may be, for example, a hardening layer of an acrylic resin, a silicone resin, a polyester resin, a polyurethane resin, an amide resin, an epoxy resin, etc. The hard coating layer may also contain additives to increase strength.

The additives are not limited and can be listed as: inorganic microparticles, organic microparticles or mixtures thereof. The hard coating layer is, for example, a hardened layer of a UV-curing resin. UV-curing resins can be listed as: acrylic resins, silicone resins, polyester resins, polyurethane resins, amide resins, epoxy resins, etc.

The thickness of the protective film 11 is usually between 1 μm and 100 μm. From the perspective of strength and usability, it is preferably between 5 μm and 80 μm, more preferably between 8 μm and 60 μm, and even more preferably between 12 μm and 45 μm. It can also be less than 30 μm.

[Then the agent layer]

The adhesive layer 12 can exist between the protective film 11 and the polarizer 10 to bond the two. The adhesive forming the adhesive layer 12 can be listed as: water-based adhesive, active energy ray curing adhesive or thermosetting adhesive, preferably using water-based adhesive or active energy ray curing adhesive. The surfaces of the protective film 11 and the polarizer 10 bonded oppositely through the adhesive layer 12 can be pre-treated with corona treatment, plasma treatment, flame treatment, etc., and can also have a primer layer, etc.

In order to ensure the adhesion between the protective film 11 and the polarizer 10, the thickness of the adhesive layer 12 is usually greater than 0.01μm and usually less than 10μm.

[First adhesive layer]

The moisture permeability of the first adhesive layer 13 at a temperature of 40°C and a relative humidity of 90% RH (hereinafter referred to as "moisture permeability") is 500 g/(m ² ·day) or less. The moisture permeability can be measured by the measuring method described in the column of the embodiments described later.

Polarizing plates with adhesive layers can be bonded to organic EL display elements or liquid crystal units (usually inorganic glass surfaces) through their adhesive layers. When the polarizer is a hydrophilic resin film, it tends to have poor moisture and heat resistance after being bonded to an inorganic glass surface, and iodine release is likely to occur at the ends of the polarizer. First, in polarizing plates with adhesive layers, where a protective film is only arranged on one side of the polarizer through an adhesive layer, and an adhesive layer is directly arranged on the other side, iodine release is likely to occur. The polarizing plate 100 with adhesive layer has a tendency to suppress iodine release easily by making the moisture permeability of the first adhesive layer 13 less than 500 g/(m ² ·day). In addition, when protective films are laminated on both sides of the polarizer through adhesive layers (double-sided protective polarizing plate), such iodine release tends to be difficult to occur.

The moisture permeability of the first adhesive layer 13 is preferably 400 g/(m ² ·day) or less, more preferably 300 g/(m ² ·day) or less, and even more preferably 200 g/(m ² ·day) or less. There is no particular restriction on the lower limit of the moisture permeability, but it is ideal to prevent water vapor from completely passing through (i.e., 0 g/(m ² ·day)). The moisture permeability can be determined by the method described in the embodiment.

The composition of the adhesive forming the first adhesive layer 13 is not particularly limited, and a layer containing any appropriate adhesive may be used. The adhesive may include, for example, rubber adhesives, polyolefin adhesives, acrylic adhesives, silicone adhesives, polyurethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, cellulose adhesives, etc., but from the perspective of moisture permeability, rubber adhesives or polyolefin adhesives are preferred.

Rubber-based adhesives are only required to contain rubber-based polymers, and their composition is not particularly specified.

The rubber polymer used in the present invention is a polymer that exhibits rubber elasticity in a temperature range near room temperature. Specifically, styrene-based thermoplastic elastomers, isobutylene-based polymers, etc. can be listed. From the perspective of weather resistance, polyisobutylene (PIB), which is a single isobutylene polymer, is preferably used in the present invention. This is because polyisobutylene does not contain double bonds in the main chain, making it excellent in light resistance.

The aforementioned polyisobutylene may be a commercially available product such as OPPNOL manufactured by BASF.

The weight average molecular weight (Mw) of the polyisobutylene is preferably 100,000 or more, more preferably 300,000 or more, more preferably 600,000 or more, and particularly preferably 700,000 or more. Furthermore, there is no particular restriction on the upper limit of the weight average molecular weight, but it is preferably 5 million or less, more preferably 3 million or less, and even more preferably 2 million or less. By setting the weight average molecular weight of the polyisobutylene to 100,000 or more, a rubber-based adhesive with better durability during high temperature storage can be made.

The content of the aforementioned polyisobutylene is not particularly limited, but preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and particularly preferably 90% by mass or more in the total solid content of the rubber adhesive. The upper limit of the content of polyisobutylene is not particularly limited, but preferably 99% by mass or less, and even more preferably 98% by mass or less. By containing polyisobutylene within the aforementioned range, low moisture permeability can be excellent and preferred.

Furthermore, the rubber adhesive used in the present invention may contain polymers or elastomers other than the aforementioned polyisobutylene. Specifically, the copolymers of isobutylene and norbornene, the copolymers of isobutylene and isoprene (e.g., regular butyl rubber) and the like may be included. isobutylene polymers such as styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-propylene-styrene block copolymer (SEPS, hydrogenated products of SIS), styrene-ethylene-propylene copolymer (SEP, styrene-isoprene ...EP, styrene-isoprene-styrene block copolymer (SBS), styrene-ethylene-propylene-styrene block copolymer (SEPS, hydrogenated products of SIS), styrene-ethylene-propylene copolymer (SEP, styrene-isoprene-styrene block copolymer (SEP, styrene-isoprene-styrene block copolymer (SBS), styrene-ethylene-propylene-styrene block copolymer (SEPS, hydrogenated products of SIS), styrene-ethylene-propylene copolymer Styrene-based thermoplastic elastomers such as styrene-based block copolymers such as hydrogenated copolymers of styrene-isoprene-styrene block copolymers (SIBS) and styrene-butadiene rubber (SBR); butyl rubber (IIR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), EPR (binary ethylene-propylene rubber), EPT (ternary ethylene-propylene rubber), acrylic rubber, urethane rubber, polyurethane-based thermoplastic elastomers; polyester-based thermoplastic elastomers; mixed thermoplastic elastomers such as polymer mixtures of polypropylene and EPT (ternary ethylene-propylene rubber), etc. These polymers can be added within a range that does not impair the effects of the present invention, but preferably less than 10 parts by weight relative to 100 parts by weight of the aforementioned polyisobutylene. From the perspective of durability, it is better not to contain them.

Furthermore, the rubber-based adhesive used in the present invention preferably contains the aforementioned polyisobutylene and a dehydrogenation type (hydrogen abstraction type) photopolymerization initiator.

The aforementioned dehydrogenation type photopolymerization initiator refers to an initiator that does not cleave by irradiation with active energy rays, but can form a reaction point in the polyisobutylene by dehydrogenating from the aforementioned polyisobutylene. The crosslinking reaction of the polyisobutylene starts by the formation of the reaction point.

Regarding the photopolymerization initiator, in addition to the dehydrogenation-type photopolymerization initiator used in the present invention, there is also a cleavage-type photopolymerization initiator, which generates free radicals by cleavage and decomposition of the photopolymerization initiator itself under irradiation with active energy rays. However, when a cleavage-type photopolymerization initiator is used for the polyisobutylene used in the present invention, there is a concern that the main chain of the polyisobutylene may be cut by the photopolymerization initiator that generates free radicals, and crosslinking may not be performed. In the present invention, by using a dehydrogenation-type photopolymerization initiator, crosslinking of polyisobutylene as described above can be performed.

Examples of dehydrogenation type photopolymerization initiators include acetophenone, benzophenone, o-benzoylbenzoic acid methyl ester-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-dichlorobenzophenone, 4,4'-dimethylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylic benzophenone, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 3,3'-dimethyl-4-methoxybenzophenone and the like benzophenone compounds; 2- Thiathione compounds such as isopropylthione, 2,4-dimethylthione, 2,4-diethylthione, and 2,4-dichlorothione; aminobenzophenone compounds such as 4,4'-bis(dimethylamino)benzophenone and 4,4'-diethylaminobenzophenone; 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, camphorquinone, etc.; aromatic ketone compounds such as acetonaphthone and 1-hydroxycyclohexylphenyl ketone; aromatic aldehydes such as terephthalaldehyde, and quinone aromatic compounds such as methylanthraquinone. These compounds can be used alone or in combination of two or more. Among these compounds, benzophenone compounds are preferred in terms of reactivity, and benzophenone is more preferred.

Relative to 100 parts by mass of the aforementioned polyisobutylene, the content of the aforementioned dehydrogenation-type photopolymerization initiator is preferably 0.001 to 10 parts by mass, more preferably 0.005 to 10 parts by mass, and even more preferably 0.01 to 10 parts by mass. By containing the dehydrogenation-type photopolymerization initiator within the aforementioned range, the crosslinking reaction can be carried out to the target density, which is preferred.

Furthermore, within the scope of not impairing the effect of the present invention, although the present invention can use a cleavage-type photopolymerization initiator along with the aforementioned dehydrogenation-type photopolymerization initiator, it is better not to use it for the reasons mentioned above.

The rubber adhesive used in the present invention may further contain a multifunctional free radical polymerizable compound. In the present invention, the multifunctional free radical polymerizable compound functions as a crosslinking agent for polyisobutylene.

The aforementioned multifunctional free radical polymerizable compound is a compound having at least two free radical polymerizable functional groups having unsaturated double bonds such as (meth)acryl or vinyl groups. Specific examples of the multifunctional free radical polymerizable compound 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-butylpropylene glycol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A di-dehydroglyceryl ether di(meth)acrylate, and bisphenol A di-dehydroglyceryl ether di(meth)acrylate. )acrylate, neopentyl glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, dioxanediol di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, EO-modified diglycerol tetra(meth)acrylate and other (meth)acrylic acid and polyol esters, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene and the like. These compounds may be used alone or as a mixture of two or more. From the perspective of compatibility with polyisobutylene, among these compounds, the esters of (meth)acrylic acid and polyols are preferred, and bifunctional (meth)acrylates having two (meth)acryloyl groups and trifunctional (meth)acrylates having three or more (meth)acryloyl groups are more preferred, and tricyclodecanedimethanol di(meth)acrylate and trihydroxymethylpropane tri(meth)acrylate are particularly preferred.

The content of the multifunctional free radical polymerizable compound is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less relative to 100 parts by mass of the polyisobutylene. Furthermore, the lower limit of the content of the multifunctional free radical polymerizable compound is not particularly limited, but for example, it is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more relative to 100 parts by mass of the polyisobutylene. From the perspective of the durability of the obtained rubber-based adhesive layer, it is preferred that the content of the multifunctional free radical polymerizable compound is within the above range.

The molecular weight of the multifunctional free radical polymerizable compound is not particularly limited, but is preferably about 1,000 or less, and more preferably about 500 or less, for example.

The rubber adhesive used in the present invention may contain at least one adhesive selected from the group consisting of adhesives containing a terpene skeleton, adhesives containing a rosin skeleton, and hydrogenated products thereof. By containing an adhesive in the rubber adhesive, it can have high adhesion to various coatings, and a rubber adhesive layer with high durability can be formed even in a high temperature environment, so it is preferred.

Examples of the aforementioned adhesive agent containing a terpene skeleton include terpene polymers such as α-pinene polymers, β-pinene polymers, and dipentene polymers, or modified terpene resins obtained by modifying the aforementioned terpene polymers (phenol modification, styrene modification, aromatic modification, hydrogenation modification, hydrocarbon modification, etc.). Examples of the aforementioned modified terpene resins include terpene phenol resins, styrene modified terpene resins, aromatic modified terpene resins, hydrogenated modified terpene resins (hydrogenated terpene resins), etc. Examples of the hydrogenated terpene resins referred to herein include hydrogenated products of terpene polymers and other modified terpene resins and hydrogenated products of terpene phenol resins. Among these, hydrogenated terpene phenol resins are preferred from the perspective of compatibility with rubber adhesives or adhesive properties.

The aforementioned adhesive imparting agent containing a rosin skeleton can be listed as follows: rosin resin, polymerized rosin resin, hydrogenated rosin resin, rosin ester resin, hydrogenated rosin ester resin, rosin phenol resin, etc. Specifically, unmodified rosins (raw rosins) such as rubber rosin, wood rosin, tall oil rosin (or tall oil rosin) or modified rosins obtained by hydrogenating, non-homogenizing, polymerizing, or other chemically modifying such rosins, and their derivatives can be used.

The aforementioned adhesive imparting agent may be, for example, the Clearon series and Polyster series manufactured by Yasuhara Chemical Co., Ltd.; the Super Ester series, Pencel series, and Matsubara series manufactured by Arakawa Chemical Industries, Ltd., etc.

When the aforementioned adhesion imparting agent is a hydrogenated additive, the hydrogenation may be a partially hydrogenated additive or a fully hydrogenated additive in which all double bonds in the compound are hydrogenated. In the present invention, a fully hydrogenated additive is preferred from the perspective of adhesion properties, weather resistance or color.

From the perspective of adhesive properties, the aforementioned adhesive agent preferably contains a cyclohexanol skeleton. Although the detailed principle is not clear, it is believed that the cyclohexanol skeleton has a better compatibility with polyisobutylene, which is a base polymer, than the phenol skeleton. The adhesive agent containing the cyclohexanol skeleton is preferably a hydrogenated product of terpene phenol resin, rosin phenol resin, etc., and more preferably a completely hydrogenated product of terpene phenol resin, rosin phenol resin, etc.

The softening point (softening temperature) of the aforementioned adhesive agent is not particularly limited, but is preferably, for example, above about 80°C, and more preferably above about 100°C. The softening point of the adhesive agent is preferably above 80°C, because the adhesive agent does not soften even at high temperatures and maintains adhesive properties, which is preferred. There is no particular upper limit on the softening point of the adhesive agent, but when the softening point is too high, the molecular weight becomes higher, and there are cases where undesirable problems such as deterioration of compatibility and whitening occur, so it is preferably, for example, below about 200°C, and preferably below about 180°C. In addition, the softening point of the adhesive agent referred to here is defined as the value measured according to the softening point test method (globe method) specified in either JIS K5902 or JIS K2207.

The weight average molecular weight (Mw) of the aforementioned adhesive agent is not particularly limited, but preferably 50,000 or less, preferably 30,000 or less, more preferably 10,000 or less, more preferably 8,000 or less, and particularly preferably 5,000 or less. Furthermore, the lower limit of the weight average molecular weight of the aforementioned adhesive agent is not particularly limited, but preferably 500 or more, more preferably 1,000 or more, and even more preferably 2,000 or more. When the weight average molecular weight of the aforementioned adhesive agent is within the aforementioned range, it is preferred because the compatibility between it and polyisobutylene can be improved and undesirable problems such as whitening can not be generated.

The amount of the aforementioned adhesive agent added is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less relative to the aforementioned polyisobutylene 100 parts by mass. Furthermore, the lower limit of the amount of the adhesive agent added is not particularly limited, but is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more. It is preferred that the amount of the adhesive agent added is within the aforementioned range because the adhesiveness can be improved. Furthermore, if the amount of the adhesive agent used exceeds the aforementioned range and is added in large amounts, the cohesive force of the adhesive tends to decrease, which is not good.

Furthermore, the rubber-based adhesive used in the present invention may also contain an adhesive other than the adhesive containing the aforementioned terpene skeleton and the adhesive containing the rosin skeleton. The adhesive may be a petroleum resin-based adhesive. The petroleum-based adhesive may include, for example, aromatic petroleum resins, aliphatic petroleum resins, alicyclic petroleum resins (aliphatic cyclic petroleum resins), aliphatic/aromatic petroleum resins, aliphatic/alicyclic petroleum resins, hydrogenated petroleum resins, Kumaron-based resins, Kumaron-indene-based resins, etc.

The aforementioned petroleum resin-based adhesive can be used within the scope that does not impair the effect of the present invention, but for example, less than about 30 parts by mass can be used relative to 100 parts by mass of the aforementioned polyisobutylene.

An organic solvent may be added to the aforementioned rubber adhesive as a diluent. There is no particular limitation on the diluent, and examples thereof include toluene, xylene, n-heptane, dimethyl ether, etc. Such solvents may be used alone or in combination of two or more. Among such solvents, toluene is preferred.

There is no particular restriction on the amount of diluent added, but it is preferably about 50 to 95% by mass in the rubber adhesive, and more preferably about 70 to 90% by mass. From the perspective of coating properties on a support, etc., it is preferred that the amount of diluent added is within the aforementioned range.

Additives other than the above mentioned may be added to the rubber adhesive used in the present invention within the scope that does not impair the effect of the present invention. Specific examples of additives include: softeners, crosslinkers (e.g., polyisocyanates, epoxy compounds, alkyl etherified melamine compounds, etc.), fillers, anti-aging agents, ultraviolet absorbers, etc. The types, combinations, and amounts of additives that can be added to the rubber adhesive can be appropriately set according to the purpose. The content (total amount) of the above mentioned additives in the rubber adhesive is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

The rubber adhesive layer used in the present invention can be formed by the aforementioned rubber adhesive, and its manufacturing method is not particularly limited. The rubber adhesive can be applied to various supports, etc., and the adhesive layer can be formed by heating and drying or irradiating active energy rays.

When polyisobutylene is contained as the aforementioned rubber adhesive, it is preferred to crosslink the aforementioned polyisobutylene by irradiating the rubber adhesive with active energy rays. The irradiation with active energy rays is usually performed by applying the aforementioned rubber adhesive on various supports, etc., and irradiating the obtained coating layer. Furthermore, the irradiation with active energy rays can be performed directly on the coating layer (without adhering other components, etc.), or after attaching optical films such as isolation films or various components such as glass to the coating layer. When irradiating after attaching the aforementioned optical films or various components, the irradiation can be performed across the optical films or various components, or the optical films or various components can be peeled off and the active energy rays can be irradiated from the peeled surface.

The aforementioned rubber adhesive can be applied by various methods. Specifically, for example, roller coating, kiss roller coating, gravure coating, reverse coating, roller brush, spray coating, dip coating, rod coating, knife coating, air knife coating, curtain coating, lip coating, extrusion coating using a die coating machine, and other methods can be cited.

When the coating layer of the aforementioned rubber adhesive is heated and dried, the heating and drying temperature is preferably about 30°C to 200°C, more preferably about 40°C to 180°C, and even more preferably about 80°C to 150°C.

By setting the heating temperature to the above range, a rubber adhesive layer with excellent adhesive properties can be obtained. The drying time can be appropriate and suitable. The above drying time is preferably about 5 seconds to 20 minutes, more preferably about 30 seconds to 10 minutes, and even more preferably about 1 minute to 8 minutes.

Furthermore, when the coating layer of the aforementioned rubber adhesive is irradiated with active energy rays, if the aforementioned adhesive or adhesive contains an organic solvent as a diluent, it is also preferred to remove the solvent by heating and drying after coating and before irradiating with active energy rays.

There is no particular limitation on the aforementioned heating and drying temperature, but from the perspective of reducing residual solvents, it is preferably about 30°C to 90°C, and more preferably about 60°C to 80°C. The drying time can be an appropriate and suitable time. The aforementioned drying time is preferably about 5 seconds to 20 minutes, more preferably about 30 seconds to 10 minutes, and even more preferably about 1 minute to 8 minutes.

The aforementioned active energy rays include, for example, visible light, ultraviolet light, electron beam, etc. Among these rays, ultraviolet light is preferred.

The UV irradiation conditions are not particularly limited and can be set to any appropriate conditions according to the composition of the crosslinked rubber adhesive, but preferably the irradiation cumulative light dose is 100 mJ/cm ² to 2,000 mJ/cm ² .

The aforementioned support body may be, for example, a peeling-treated sheet (isolation film).

Although the constituent materials of the aforementioned isolation film can be listed as: plastic films such as polyethylene, polypropylene, polyethylene terephthalate, polyester film, porous materials such as paper, cloth, non-woven fabric, net, foam sheet, metal foil and suitable thin leaves such as laminates thereof, etc., it is better to use plastic film in terms of excellent surface smoothness.

The aforementioned plastic films include, for example, polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

The thickness of the aforementioned isolation film is usually 5 to 200 μm, preferably about 5 to 100 μm. The aforementioned isolation film can be subjected to release and antifouling treatment using release agents of polysiloxane, fluorine, long-chain alkyl or fatty acid amide, silicon oxide powder, etc., or antistatic treatment of coating, kneading, evaporation, etc. as needed. In particular, by appropriately performing release treatments such as polysiloxane treatment, long-chain alkyl treatment, fluorine treatment, etc. on the surface of the aforementioned isolation film, the releasability from the aforementioned adhesive layer can be further improved.

When the aforementioned rubber adhesive layer is formed on a peeling-treated sheet (isolation film), the rubber adhesive layer can be transferred to the functional layer to form the polarizing plate with an adhesive layer of the present invention.

Furthermore, the gel fraction of the rubber adhesive layer used in the present invention is not particularly limited, but is preferably about 10 to 98%, more preferably about 25 to 98%, and even more preferably about 45 to 90%. By making the gel fraction within the aforementioned range, both durability and adhesion can be achieved, which is better.

As long as the polyolefin adhesive contains a polyolefin resin, its composition is not particularly limited.

Specific examples of polyolefin resins include: low-density polyethylene, ultra-low-density polyethylene, low-crystalline polypropylene, amorphous propylene-(1-butene) copolymers, ionomer resins, ethylene-vinyl acetate copolymers, ethylene-(meth)acrylate copolymers, ethylene-(meth)acrylate-maleic anhydride copolymers, ethylene-methacrylate dehydrated glyceryl copolymers and other ethylene copolymers or polyolefin modified polymers, etc.

The adhesive layer containing a polyolefin resin (hereinafter also referred to as a polyolefin adhesive layer) preferably contains an amorphous polypropylene resin, and more preferably contains an amorphous propylene-(1-butene) copolymer. As long as it is such a polyolefin adhesive layer, an adhesive sheet with excellent step followability can be obtained. In addition, in this specification, "amorphous" refers to a property that does not have a clear melting point like a crystalline substance.

The content ratio of the amorphous propylene-(1-butene) copolymer contained in the polyolefin adhesive can be appropriately adjusted so that the elasticity value of the polyolefin adhesive layer is less than 0.7N/mm. The content ratio of the amorphous propylene-(1-butene) copolymer contained in the polyolefin adhesive is preferably 10% by mass to 100% by mass, and more preferably 10% by mass to 95% by mass.

The amorphous propylene-(1-butene) copolymer is preferably obtained by polymerizing propylene and 1-butene using a metallocene catalyst. More specifically, the amorphous propylene-(1-butene) copolymer can be obtained by performing the following steps: for example, a step of polymerizing propylene and 1-butene using a metallocene catalyst, a step of removing residual catalyst after the polymerization step, and a step of removing foreign matter. The amorphous propylene-(1-butene) copolymer can be obtained in a shape such as a powder or granules through such steps. Examples of metallocene catalysts include: metallocene homogeneous mixed catalysts containing metallocene compounds and aluminoxane, metallocene supported catalysts in which metallocene compounds are supported on a microparticle carrier, etc.

The amorphous propylene-(1-butene) copolymer polymerized using the metallocene catalyst exhibits a narrow molecular weight distribution. The molecular weight distribution (Mw/Mn) of the amorphous propylene-(1-butene) copolymer is preferably 3 or less, more preferably 2 or less, more preferably 1.1 to 2, and particularly preferably 1.2 to 1.9. The amorphous propylene-(1-butene) copolymer with a narrow molecular weight distribution has a small amount of low molecular weight components, so by using such an amorphous propylene-(1-butene) copolymer, a polyolefin adhesive layer that prevents the coating from being contaminated by the penetration of low molecular weight components can be obtained.

The content ratio of the constituent units derived from propylene in the above-mentioned amorphous propylene-(1-butene) copolymer is preferably 80 mol% to 99 mol%, more preferably 85 mol% to 99 mol%, and even more preferably 90 mol% to 99 mol%.

The content ratio of the constituent units derived from 1-butene in the above-mentioned amorphous propylene-(1-butene) copolymer is preferably 1 mol% to 20 mol%, more preferably 1 mol% to 15 mol%, and even more preferably 1 mol% to 10 mol%. As long as it is within this range, an adhesive layer with an excellent balance of toughness and softness can be obtained.

The above-mentioned amorphous propylene-(1-butene) copolymer may be a block copolymer or a random copolymer.

The weight average molecular weight (Mw) of the amorphous propylene-(1-butene) copolymer is preferably 200,000 or more, more preferably 200,00 to 500,00, and even more preferably 200,00 to 300,00. As long as the weight average molecular weight (Mw) of the amorphous propylene-(1-butene) copolymer is within this range, compared with general styrene-based thermoplastic resins and acrylic thermoplastic resins (Mw is 100,000 or less), an adhesive layer with less low molecular weight components can be obtained, which can prevent contamination of the coating.

The melt flow rate of the amorphous propylene-(1-butene) copolymer at 230°C and 2.16kgf is preferably 1g/10min to 50g/10min, more preferably 5g/10min to 30g/10min, and even more preferably 5g/10min to 20g/10min. As long as the melt flow rate of the amorphous propylene-(1-butene) copolymer is within such a range, an adhesive layer with uniform thickness and no processing defects can be formed by co-extrusion molding. The melt flow rate can be measured by the method according to JIS K 7210.

Without prejudice to the effects of the present invention, the amorphous propylene-(1-butene) copolymer further contains constituent units from other monomers. Other monomers include, for example, ethylene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, 3-methyl-1-pentene and other α-olefins.

The amorphous propylene-(1-butene) copolymer may contain constituent units from other monomers within the scope of not impairing the effects of the present invention. Other monomers include, for example, ethylene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, 3-methyl-1-pentene and other α-olefins.

The adhesive layer preferably contains a crystalline polypropylene resin. By containing a crystalline polypropylene resin, the elastic modulus E' of the adhesive layer at 70°C can be adjusted to a desired value. The content ratio of the crystalline polypropylene resin can be set to any appropriate ratio according to the required elastic modulus E'. The content ratio of the crystalline polypropylene resin relative to the total weight of the amorphous propylene-(1-butene) copolymer and the crystalline polypropylene resin is preferably 0 mass % to 90 mass %, and more preferably 5 mass % to 90 mass %.

The above-mentioned crystalline polypropylene resin can be a homogeneous polypropylene or a copolymer obtained by copolymerizing propylene and a monomer copolymerizable with propylene. Examples of monomers copolymerizable with propylene include ethylene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, 3-methyl-1-pentene and other α-olefins. When the above-mentioned crystalline polypropylene resin is a copolymer obtained by copolymerizing propylene and a monomer copolymerizable with propylene, it can be a random copolymer or a block copolymer.

The above-mentioned crystalline polypropylene resin is preferably obtained by using a metallocene catalyst, similarly to the above-mentioned amorphous propylene-(1-butene) copolymer. By using the crystalline polypropylene resin obtained in this way, the coating can be prevented from being contaminated by the leakage of low molecular weight components.

The crystallization degree of the above-mentioned crystalline polypropylene resin is preferably 10% or more, and more preferably 20% or more. The crystallization degree can be obtained by representative differential scanning calorimetry (DSC) or X-ray diffraction.

The polyolefin adhesive layer is preferably substantially free ^{of F-, Cl-, Br-, NO2-, NO3-, SO42- , Li +} _, ^Na ₊ ^, K ⁺ , ^{Mg2+ ,} Ca2 ^{+ ,} _{and NH4} ⁺ . This can prevent the coating from being contaminated by the ions. The polyolefin adhesive layer free of the ions can be obtained, for example, by solution polymerizing the amorphous propylene-(1-butene) copolymer contained in the polyolefin adhesive layer using the metallocene catalyst described above. In the solution polymerization using the metallocene catalyst, the amorphous propylene-(1-butene) copolymer is purified by repeatedly precipitating single ions (reprecipitation method) using a poor solvent different from the polymerization solvent, so that a polypropylene-based adhesive layer free of the above ions can be obtained. In addition, _in this specification, "substantially free ^{of F-, Cl-, Br-, NO2-, NO3-, SO42- , Li + ,} _{Na +} ^{, K + ,} Mg2 ⁺ , Ca2 ⁺ , _NH4 ⁺ " means that the content is below the detection limit in the analysis using a standard ion chromatography instrument (for example, ion chromatography analysis using the trade names "DX-320" and "DX-500" manufactured by Dionex Corporation). Specifically, it means that for 1 gram of the polyolefin-based adhesive layer, the contents of F ^- , Cl ^- , Br ^- , NO ₂ ^- , NO ₃ ^- , SO ₄ ^2- , and K ⁺ are respectively less than 0.49 μg, the contents of Li ⁺ and Na ⁺ are respectively less than 0.20 μg, the contents of Mg ²⁺ and Ca ²⁺ are respectively less than 0.97 μg, and the contents of NH ₄ ⁺ are respectively less than 0.5 μg.

The method for producing the polyolefin adhesive layer can be applied to the method for producing the rubber adhesive layer described above.

The first adhesive layer 13 may contain other additives within the scope of not impairing the effect of the present invention. The additives may include, for example, antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, antistatic agents, solvents, crosslinking catalysts, thickeners, plasticizers, softeners, pigments, inorganic fillers, organic fillers, etc. The type and amount of additives may be appropriately selected according to the purpose. These additives may be one type or a combination of two or more types.

The thickness of the first adhesive layer 13 is not particularly limited, and can be appropriately set according to its use, but can be, for example, less than 250 μm. From the perspective of thinning, it is preferably less than 100 μm, more preferably less than 50 μm, more preferably less than 40 μm, particularly preferably less than 30 μm, and particularly preferably less than 27 μm. There is no particular limit to the lower limit of the thickness of the first adhesive layer 13, but from the perspective of durability, it can be, for example, more than 1 μm, preferably more than 5 μm, more preferably more than 10 μm, more preferably more than 15 μm, and particularly preferably more than 20 μm.

[Second adhesive layer]

The second adhesive layer 14 may exist between the polarizer 10 and the functional layer 15 to bond the two. The second adhesive layer 14 may be composed of the same adhesive composition as the adhesive composition forming the first adhesive layer 13, or may be composed of an adhesive composition having a resin such as (meth) acrylic acid, rubber, polyurethane, ester, polysilicone, or polyvinyl ether as a main component. The second adhesive composition is preferably an adhesive composition having a (meth) acrylic resin having excellent transparency, weather resistance, heat resistance, etc. as a base polymer. The second adhesive composition may be an active energy ray curing type or a thermosetting type.

The thickness of the second adhesive layer 14 can be, for example, 2 μm to 30 μm, preferably 3 μm to 20 μm. It can be, for example, 10 μm or more, but in terms of thinness, it is 15 μm or less, preferably 10 μm or less, and particularly preferably 7 μm or less.

[Functional layer]

The functional layer 15 is a single layer of a liquid crystal curing layer, or a plurality of layers of two or more selected from the group of a liquid crystal curing layer, an alignment layer, and a bonding layer. The functional layer 15 preferably contains two layers of liquid crystal curing layers, and more preferably contains two layers of liquid crystal curing layers stacked through a bonding layer.

[Liquid crystal hardening layer]

The liquid crystal cured layer can be a phase difference layer formed by coating and aligning the polymerizable liquid crystal compound on a substrate to form a cured polymerizable liquid crystal compound that exhibits optical anisotropy. The phase difference layer of the cured polymerizable liquid crystal compound can be exemplified by the first to fifth types.

Type 1: The rod-shaped liquid crystal compound is a phase difference layer oriented in the horizontal direction relative to the supporting substrate

Second type: The rod-shaped liquid crystal compound is a phase difference layer oriented in a vertical direction relative to the supporting substrate

The third type: The rod-shaped liquid crystal compound is a phase difference layer whose orientation direction changes in a spiral shape within the plane.

The fourth type: the phase difference layer of the discotic liquid crystal compound is tilted

Fifth type: The disc-shaped liquid crystal compound is a phase difference layer oriented in a direction perpendicular to the supporting substrate

For example, the optical film used in the organic electroluminescent display can be applied to the first type, the second type, and the fifth type. Furthermore, these types of phase difference layers can also be stacked and used.

When the phase difference layer is a layer formed by a polymer in the alignment state of a polymerizable liquid crystal compound (hereinafter also referred to as an "optical anisotropic layer"), the phase difference layer preferably has reverse wavelength dispersion. Reverse wavelength dispersion refers to the optical property that the in-plane phase difference value of the liquid crystal alignment in a short wavelength is smaller than the in-plane phase difference value of the liquid crystal alignment in a long wavelength. It is preferred that the phase difference film satisfies the following formula (1) and formula (2). In addition, Re(λ) represents the in-plane phase difference value relative to light of wavelength λ nm.

Re(450)/Re(550)≦1 (1)

1≦Re(630)/Re(550) (2)

When the phase difference layer is of the first type and has reverse wavelength dispersion, it is better because the coloring of the black display in the display is reduced. In the above formula (1), it is better as long as 0.82≦Re(450)/Re(550)≦0.93. In addition, 120≦Re(550)≦150 is better.

The polymerizable liquid crystal compounds used to form the phase difference layer can be exemplified by "3.8.6 Liquid Crystal Handbook" (Edited by Liquid Crystal Handbook Editorial Committee, published by Maruzen Co., Ltd. on October 30, 2001). Network (Completely Cross-linked)", "6.5.1 Liquid Crystal Material b. Polymerizable Nematic Liquid Crystal Material", and compounds having polymerizable groups among the compounds described in Japanese Patent Publication No. 2010-31223, Japanese Patent Publication No. 2010-270108, Japanese Patent Publication No. 2011-6360, Japanese Patent Publication No. 2011-207765, Japanese Patent Publication No. 2011-162678, Japanese Patent Publication No. 2016-81035, International Publication No. 2017/043438 and Japanese Patent Table No. 2011-207765.

The method of manufacturing a phase difference layer from a polymer in an aligned state of a polymerizable liquid crystal compound can be exemplified by the method described in Japanese Patent Publication No. 2010-31223.

The thickness of the phase difference layer of the liquid crystal curing layer formed by curing the polymerizable liquid crystal compound is, for example, 0.1 μm to 10 μm, preferably 0.5 μm to 8 μm, and more preferably 1 μm to 6 μm.

The phase difference layer can be a λ/4 phase difference layer that gives a phase difference of 1/4 wavelength to the transmitted light, a λ/2 phase difference layer that gives a phase difference of 1/2 wavelength to the transmitted light, a positive A plate, and a positive C plate. The functional layer can contain two liquid crystal curing layers. When the functional layer contains the first liquid crystal curing layer and the second liquid crystal curing layer, the liquid crystal curing layer can be a combination of a λ/2 phase difference layer and a λ/4 phase difference layer, a combination of a λ/4 phase difference layer and a positive C layer, etc.

The polarizing plate 100 with an adhesive layer can also be configured as a circular polarizing plate with a λ/4 phase difference layer. The circular polarizing plate can be used as an anti-reflection polarizing plate.

[Orientation layer]

The alignment layer can be arranged between the above-mentioned substrate and the layer of the cured product of the polymerizable liquid crystal compound. The alignment layer can align the liquid crystal cured layer formed thereon in the desired direction and has alignment control power. The alignment layer can include an alignment polymer layer formed with an alignment polymer, a photoalignment polymer layer formed with a photoalignment polymer, and a groove alignment film having a concave-convex pattern or multiple grooves (grubs) on the surface of the layer. The thickness of the alignment layer can be, for example, more than 10nm and less than 500nm, preferably more than 10nm and less than 200nm.

The alignment polymer layer is formed by coating a composition in which an alignment polymer is dissolved in a solvent on a substrate, removing the solvent, and performing a wiping treatment as required. At this time, the alignment control force in the alignment polymer layer formed with the alignment polymer can be arbitrarily adjusted according to the surface state of the alignment polymer or the wiping conditions.

The photo-aligned polymer layer is formed by coating a composition containing a polymer or monomer with a photoreactive group and a solvent on a substrate layer and irradiating it with polarized light. At this time, the alignment control force in the photo-aligned polymer layer can be arbitrarily adjusted according to the polarized light irradiation conditions for the photo-aligned polymer.

The groove alignment film can be formed, for example, by the following methods: a method of forming a concave-convex pattern by exposing and developing the surface of a photosensitive polyimide film through an exposure mask with slits having a shaped pattern; a method of forming an uncured layer of an active energy ray-curable resin on a plate-shaped original plate having grooves on the surface, and transferring the layer to a substrate for curing; a method of forming an uncured layer of an active energy ray-curable resin on a substrate, and forming concave-convex by pressing a roller-shaped original plate having concave-convex on the layer, and curing it, etc.

[Lamination layer]

The bonding layer can be configured to bond two layers. The bonding layer can be composed of a bonding agent or an adhesive. When the functional layer 15 contains two layers of liquid crystal curing layers, the two layers of liquid crystal curing layers can be bonded by the bonding layer.

The adhesive layer may include a water-based adhesive, an active energy ray-hardening adhesive, or a thermosetting adhesive. From the perspective of ensuring adhesion, the thickness of the adhesive layer 12 is between 0.01 μm and 10 μm.

The adhesive may be composed of the same adhesive composition as the adhesive composition forming the first and second adhesive layers, or may be composed of an adhesive composition having a resin such as (meth) acrylic acid, rubber, polyurethane, ester, polysilicone, or polyvinyl ether as a main component (hereinafter also referred to as "the third adhesive composition"). The third adhesive composition is preferably an adhesive composition having a (meth) acrylic acid resin excellent in transparency, weather resistance, heat resistance, etc. as a base polymer. The third adhesive composition may be an active energy ray curing type or a heat curing type. The thickness of the third adhesive layer is usually 0.1 μm to 150 μm, for example 8 μm to 60 μm, preferably 30 μm or less, and more preferably 20 μm or less from the perspective of thinning. The thickness of the third adhesive layer may be, for example, 10 μm or more, but for thinner thickness, it is 15 μm or less, preferably 10 μm or less, and particularly preferably 7 μm or less.

[Other layers]

The polarizing plate 100 with an adhesive layer may contain a protective layer for protecting the surface (such as the surface of the protective film 11) or a separator film (hereinafter also referred to as a separator layer) laminated on the outside of the first adhesive layer 13 as other layers.

〔Protective film〕

After the polarizing plate is attached to an image display or other optical components, the entire adhesive layer with the protective film can be peeled off and removed.

The protective film may be composed of, for example, a base film and an adhesive layer laminated thereon. The above description may be cited for the adhesive layer.

The resin constituting the substrate film includes, for example, polyethylene resins such as polyethylene, polypropylene resins such as polypropylene, polyester resins such as polyethylene terephthalate or polyethylene naphthalate, and thermoplastic resins such as polycarbonate resins. Polyester resins such as polyethylene terephthalate are preferred.

[Isolation film]

The separator film may be a film formed of polyethylene resins such as polyethylene, polypropylene resins such as polypropylene, polyester resins such as polyethylene terephthalate, etc. Among them, the stretched film of polyethylene terephthalate is preferred. The separator film may be subjected to a peeling treatment on the surface.

[Manufacturing method of polarizing plate with adhesive layer]

The polarizing plate 100 with an adhesive layer can be manufactured, for example, as follows. First, the polarizing element 10 and the protective film 11 are laminated through the adhesive layer 12. The polarizing plate is prepared as a long strip component, and after the individual components are bonded together by roll to roll, they are cut into a predetermined shape and bonded together. After the protective film 1 is bonded to the polarizing element 10, a heating step or a humidification step can be set.

When the functional layer 15 is a phase difference layer, it can be manufactured, for example, as follows. An alignment film is formed on a substrate, and a coating liquid containing a polymerizable liquid crystal compound is applied on the alignment film. The polymerizable liquid crystal compound is irradiated with active energy rays in an aligned state to cure the polymerizable liquid crystal compound. The first adhesive layer 13 formed on the peeling film is deposited on the cured layer of the polymerizable liquid crystal compound. Then, the substrate and/or the alignment film is peeled off. Then, the second adhesive layer 14 formed on the peeling film is deposited on the polarizer 10. The phase difference layer is manufactured by preparing long strips of components, bonding the individual components together by roller-to-roller method, and then cutting them into a predetermined shape. Alternatively, the individual components can be cut into a predetermined shape and then bonded together.

Then, by peeling off the release film layered on the second adhesive layer 14 and laminating the functional layer 15 and the polarizer 10 through the second adhesive layer 14, the polarizing plate 100 with an adhesive layer can be manufactured.

<Image Display>

The polarizing plate 100 with an adhesive layer is arranged in front of the image display panel (viewing side) and can be used as a component of the image display. When the polarizing plate with an adhesive layer is a circular polarizing plate, it can be used as an anti-reflection polarizing plate for imparting anti-reflection function in the image display. There is no particular limitation on the image display, and examples thereof include organic electroluminescent (organic EL) displays, inorganic electroluminescent (inorganic EL) displays, liquid crystal displays, electroluminescent displays, and other image displays.

[Flexible image display]

The image display may be a flexible image display. The flexible image display is formed by a laminate for a flexible image display and an organic EL display described later. For an organic EL display panel, a flexible image display laminate is arranged on the viewing side to form a bendable structure.

<Multilayer body for flexible image display>

The laminate for a flexible image display has a polarizing plate with an adhesive layer of the present invention, and a front panel or a touch sensor. The lamination order of the polarizing plate with an adhesive layer of the present invention, the front panel, and the touch sensor can be, for example, the front panel, the polarizing plate with an adhesive layer of the present invention, and the touch sensor in order from the viewing side. The lamination order is preferably the front panel, the touch sensor, and the polarizing plate with an adhesive layer of the present invention. If the polarizing plate is closer to the viewing side than the touch sensor, it will be difficult to view the pattern of the touch sensor, and the visibility of the displayed image will be improved, which is preferred. Individual components can be laminated using adhesives, adhesives, etc. Furthermore, the laminate for the flexible image display can have a light-shielding pattern formed on at least one side of any layer of the front panel, polarizing plate, and touch sensor.

[Front panel]

A front panel may be disposed on the viewing side of the polarizing plate. The front panel may be laminated on the polarizing plate via a bonding layer. The bonding layer may include, for example, the aforementioned adhesive layer or bonding layer.

The front panel may be formed by including a hard coating layer on at least one side of glass or resin film. Glass may be, for example, high-transmittance glass or reinforced glass. In particular, when using thin transparent surface materials, chemically reinforced glass is preferred. The thickness of the glass may be, for example, 100 μm to 5 mm.

The front panel formed by having a hard coating layer on at least one side of the resin film is not as rigid as the existing glass and can have the property of being bendable. The thickness of the hard coating layer is not particularly limited and can be, for example, 5 to 100 μm.

The resin film may be a cycloolefin derivative having a monomer unit containing a cycloolefin such as norbornene or polycyclic norbornene, acetyl cellulose (diethyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, isobutyl cellulose, propylene cellulose, butyryl cellulose, acetylacetyl cellulose), ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, Films formed from polymers such as polyacrylic acid, polyimide, polyamide-imide, polyether sulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, and epoxy resin. The resin film may be unstretched, uniaxially stretched, or biaxially stretched. These polymers may be used alone or in combination of two or more. The resin film is preferably a polyamide imide film or polyimide film with excellent transparency and heat resistance, a uniaxial or biaxially stretched polyester film, a cycloolefin derivative film with excellent transparency and heat resistance and capable of being scaled up, a polymethyl methacrylate film, and a triacetyl cellulose film and an isobutyl cellulose film with excellent transparency and optical anisotropy. The thickness of the resin film is 5 to 200 μm, preferably 20 to 100 μm.

[Shading pattern]

The shading pattern (bezel) can be formed on at least one side of any of the front panel, polarizing plate, and touch sensor constituting the laminate for the flexible image display. For example, it can be formed on the display element side of the front panel. The shading pattern can be made to hide the wiring of the display and not be seen by the user. There is no special restriction on the color or material of the shading pattern, and it can be formed with a resin material with various colors such as black, white, and gold. In one embodiment, the thickness of the shading pattern can be 2μm to 50μm, preferably 4μm to 30μm, and more preferably in the range of 6μm to 15μm. Furthermore, in order to suppress the mixing of bubbles and the identification of the boundary part due to the difference between the shading pattern and the display part, a shape can be given to the shading pattern.

[Touch sensor]

The touch sensor can be used as an input device. There are various proposals for touch sensors, such as impedance film method, surface elastic wave method, infrared method, electromagnetic induction method, electrostatic capacitance method, etc. Any method can be used. Among them, the electrostatic capacitance method is preferred. The electrostatic capacitance method touch sensor can be divided into an active area and an inactive area outside the aforementioned active area. The active area corresponds to the area (display part) in the display panel that displays the screen and can sense the user's touch. The inactive area corresponds to the area (non-display part) in the display panel that does not display the screen. The touch sensor may include: a substrate with bendable characteristics, a sensing pattern formed in the active area of the aforementioned substrate, and each sensing line for a driving circuit formed in the inactive area of the aforementioned substrate and connected to the outside through the aforementioned sensing pattern and the pad portion. The substrate with bendable characteristics may use the same material as the transparent substrate of the aforementioned front panel. From the perspective of suppressing cracks that may be generated on the touch sensor, the toughness of the substrate of the touch sensor is preferably 2,000MPa% or more. A better toughness is 2,000MPa% to 30,000%. Here, toughness is defined as the area below the curve to the breaking point in the stress (MPa)-strain (%) curve (Stress-Strain Curve) obtained by the tensile test of the polymer material.

[Implementation example]

The present invention is described in more detail below by way of examples. "%" and "parts" in the examples refer to mass % and mass parts unless otherwise specified.

[Moisture permeability]

Test materials:

The test material is a support (layer) with a moisture permeability exceeding 70,000g/(m ² ‧day) and a first adhesive layer bonded to the surface alone.

Method for measuring moisture permeability:

Using a water vapor permeameter [Lyssy80-4000 manufactured by Systech Illinois (UK), in accordance with JIS K7129-1:2019 (humidity sensor method)], under the conditions of a measurement area of 0.07 to 51 ^cm2 , a temperature of the permeation unit of 40°C, and a relative humidity of 90%RH in the high humidity chamber, the measurement start threshold on the low humidity chamber side was set at a relative humidity of 9.7%RH and the measurement was started. The time required for the relative humidity of the low humidity chamber to change from 9.9%RH to 10.1%RH was measured, and the moisture permeability was calculated as the water vapor permeability.

[Evaluation of iodine release]

As shown in Figure 2, when the protective film A side (A side) of the polarizing plate with an adhesive layer is made into the upper side, the angle α of the long side L2 relative to the absorption axis T of the polarizer is made to be 45°, and it is cut into a rectangle of 120mm (L2) × 60mm (L1), and then attached to an alkali-free glass plate (Corning, trade name "Eagle-XG"), and placed in an environment of temperature 65°C and humidity 90%RH for 504 hours. Then, a polarizing plate is attached to the alkali-free glass surface opposite to the tested polarizing plate with an adhesive layer, forming a cross-Nicole's relationship, and observed with an optical microscope, and the observed image is saved. The optical microscope used was "VHX-500" manufactured by KEYENCE Co., Ltd. FIG3 shows an example of an observation image of the polarizing plate with an adhesive layer applied and observed using the optical microscope. This observation image is an observation image of the polarizing plate with an adhesive layer obtained by Example 1 described later.

In this Figure 3, when observing along the straight line indicated by the arrow from the end of the polarizing plate with the adhesive layer to the inner side (the straight line drawn in white from the end 50 in the vertical direction), it can be seen that there is an iodine release area 51 and an area where iodine is not released (non-iodine release area) 52.

[Measurement of iodine release by image processing]

The image observed under a microscope shown in FIG3 is a gray image converted into black and white 256-color gradation (0 to 255) using the image analysis software "Image J (free software)". The method of converting into black and white 256-color gradation (0 to 255) uses the method of obtaining the average of RGB values. FIG4 shows the appearance (contour) data of the color gradation plotted along the straight line drawn in white for the observation image converted into black and white 256-color gradation shown in FIG3. The middle point (middle of iodine release gradient) between the iodine release area 51 and the non-iodine release area 52 in the color scale appearance relative to the direction perpendicular to the end 50 of the polarizing plate with the adhesive layer (arrow in FIG. 4) is taken as the iodine release end of the polarizing plate with the adhesive layer (FIG. 4), and the distance (μm) from the iodine release end of the end 50 of the polarizing plate with the adhesive layer is measured as the iodine release distance. The iodine release distance of the polarizing plate with the adhesive layer is shown in Table 1. The smaller the iodine release distance, the narrower the range of iodine release, and the better the moisture and heat resistance.

[Single-sided protective polarizing plate]

(Production of polarizers)

A polyvinyl alcohol film with a thickness of 20 μm, a degree of polymerization of 2,400, and a saponification degree of more than 99% was uniaxially stretched to a stretching ratio of 4.1 times on a hot roller, and then kept in a tensioned state and immersed in a dye bath containing 0.05 mass parts of iodine and 5 mass parts of potassium iodide per 100 mass parts of water at 28°C for 60 seconds.

Next, immerse in a boric acid aqueous solution containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water at 64°C for 110 seconds. Next, immerse in a boric acid aqueous solution 2 containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water at 67°C for 30 seconds. Then, wash with pure water at 10°C and dry to obtain a polarizer. The thickness of the obtained polarizer is 8μm, and the boron content is 4.3% by weight.

(Preparation of water-based adhesive)

Dissolve 3 parts by mass of carboxyl-modified polyvinyl alcohol (Kuraray Co., Ltd., trade name "KL-318") in 100 parts by mass of water, add 1.5 parts by mass of a water-soluble epoxy resin polyamide epoxy additive (Taoka Chemical Industry Co., Ltd., trade name "Smilaise resin (registered trademark) 650 (30), a 30% by weight aqueous solution of solid content concentration) to the aqueous solution to prepare a water-based adhesive.

(Protective film A and peeling film B)

As the protective film A, a film having a hard coating layer with a thickness of 3 μm formed on a stretched film formed of a cyclic polyolefin resin with a thickness of 25 μm (manufactured by Nippon Paper Industries, Ltd., trade name "COP25ST-HC") was used.

As the peeling film B, a triacetyl cellulose film (manufactured by Fuji Film Co., Ltd., "TD80UL") was used. The thickness of the peeling film was 80 μm, and the moisture permeability was 502 g/m ² · 24 hours.

(Production of single-sided protected polarizing plate)

The manufactured polarizer is continuously transported, and the protective film A is continuously rolled out from the roll of the protective film A, and the release film B is also continuously rolled out from the roll of the release film B. The water-based adhesive is injected between the polarizer and the protective film A treated with corona, and pure water is injected between the polarizer and the release film B, and the rolls are laminated to obtain a laminated film consisting of the protective film A/water-based adhesive/polarizer/pure water/release film B. The laminated film is transported and heated in a drying oven at 80°C for 300 seconds to dry the aqueous adhesive and evaporate the pure water between the polarizer and the release film B to obtain a single-sided protected polarizing plate with a release film. The release film B is peeled off from the single-sided protected polarizing plate with a release film to obtain a single-sided protected polarizing plate.

[Production of phase difference multilayer]

(Preparation of the first phase difference layer)

As the first phase difference layer, a layer that can provide a phase difference of λ/4 is used, which is composed of a first liquid crystal layer of a nematic liquid crystal compound cured layer, an alignment film, and a transparent substrate. In addition, the total thickness of the nematic liquid crystal compound cured layer and the alignment layer is 2μm.

(Preparation of the second phase difference layer)

The composition for forming the alignment layer is prepared by dissolving 10.0 parts by mass of polyethylene glycol di(meth)acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-600), 10.0 parts by mass of trihydroxymethylpropane triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-TMPT), 10.0 parts by mass of 1,6-hexanediol di(meth)acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-HD-N), and 1.50 parts by mass of Irgacure 907 (manufactured by BASF, Irg-907) as a photopolymerization initiator in 70.0 parts by mass of methyl ethyl ketone as a solvent to prepare a coating liquid for forming the alignment layer.

As the base film, a 20μm thick long strip of cyclic polyolefin resin (COP) film (produced by ZEON Co., Ltd., Japan) was prepared, and the coating liquid for forming the alignment layer was applied on one side of the base film using a bar coater.

The coated layer was heat treated at 80°C for 60 seconds and then irradiated with ultraviolet rays (UVB) of 220 mJ/cm ² to polymerize and cure the alignment layer forming composition, thereby forming an alignment layer with a thickness of 2.3 μm on the base film.

The composition for forming the phase difference layer is prepared by dissolving 20.0 parts by mass of a photopolymerizable nematic liquid crystal compound (RMM28B manufactured by Merck) and 1.0 parts by mass of Irgacure 907 (Irg-907 manufactured by BASF) as a photopolymerization initiator in 80.0 parts by mass of a solvent, propylene glycol monomethyl ether acetate, to prepare a coating liquid for forming the phase difference layer.

A coating liquid for forming a phase difference layer was applied on the alignment layer obtained above, and a heat treatment was applied to the coating layer at a temperature of 80°C for 60 seconds. Then, ultraviolet rays (UVB) of 220mJ/ ^cm2 were irradiated to polymerize and cure the phase difference layer composition, thereby forming a second liquid crystal cured layer with a thickness of 0.7μm on the alignment layer. In this way, a second phase difference layer with a thickness of 3μm consisting of an alignment layer and a phase difference layer was obtained on the substrate film.

(Production of phase difference multilayer)

The first phase difference layer and the second phase difference layer are bonded together using a UV curable adhesive (thickness 1μm) so that each liquid crystal layer surface (and the surface on the opposite side of the substrate film) becomes a bonding surface. Then, the UV curable adhesive is cured by irradiating UV rays to produce a phase difference laminate containing two phase difference layers, the first phase difference layer and the second phase difference layer. The thickness of the phase difference laminate containing the first phase difference layer, the UV curable adhesive layer and the second phase difference layer is 6μm.

(1st adhesive layer)

Adhesive layer (1): Prepare one with a moisture permeability of 160g/(m ² ·day) and a thickness of 25μm.

Adhesive layer (2): Prepare a layer with a moisture permeability of 2,000 g/(m ² ·day) and a thickness of 25 μm.

(Second adhesive layer)

Prepare a moisture permeability of 4,000g/(m ² ‧day) and a thickness of 5μm.

<Implementation Example 1>

The second adhesive layer is bonded to the polarizer side of the manufactured single-sided protected polarizing plate, and the isolation layer is peeled off. The second adhesive layer is bonded to the first liquid crystal curing layer side of the phase difference layered body from which the transparent substrate has been removed through the surface from which the isolation film has been peeled off, and the substrate film of the second phase difference layer is peeled off. The adhesive layer (1) is bonded to the surface from which the substrate film has been peeled off. The polarizing plate with an adhesive layer of Example 1 has a structure as shown in FIG. 1. The results are shown in Table 1.

<Comparison Example 1>

Except that the adhesive layer (2) is used instead of the adhesive layer (1) in Example 1, the other operations are the same as Example 1 to produce a polarizing plate with an adhesive layer. The results are shown in Table 1.

10: Polarizer

11: Protective film

12: Next is the agent layer

13: 1st adhesive layer

14: Second adhesive layer

15: Functional layer

100: Polarizing plate with adhesive layer

Claims (9)

A polarizing plate with an adhesive layer includes a polarizer, a protective film disposed on one side of the polarizer through an adhesive layer, and a second adhesive layer, a functional layer, and a first adhesive layer in order from the polarizer side on the other side of the polarizer, wherein the functional layer is a single layer of a liquid crystal curing layer, or a plurality of layers of two or more selected from a group of a liquid crystal curing layer, an alignment layer, and a bonding layer, the polarizer is a film in which iodine is adsorbed in a hydrophilic polymer film, and the moisture permeability of the first adhesive layer at a temperature of 40°C and a relative humidity of 90%RH is 160 to 500g/( ^m2 ·day). The polarizing plate with adhesive layer as described in claim 1, wherein the first adhesive layer is an adhesive layer formed by a rubber-based adhesive composition containing polyisobutylene and a dehydrogenation-type photopolymerization initiator. The polarizing plate with an adhesive layer as described in claim 1, wherein the first adhesive layer is an adhesive layer containing a polyolefin resin. The polarizing plate with an adhesive layer as described in claim 3, wherein the polyolefin resin comprises an amorphous polypropylene resin. The polarizing plate with an adhesive layer as described in any one of claims 1 to 4, wherein the thickness of the first adhesive layer is greater than 10 μm. The polarizing plate with an adhesive layer as described in any one of claims 1 to 4, wherein the protective film is a film composed of a cyclic polyolefin resin. The polarizing plate with an adhesive layer as described in any one of claims 1 to 4, wherein the functional layer comprises a first liquid crystal curing layer and a second liquid crystal curing layer. A multilayer body for a flexible image display comprises a polarizing plate with an adhesive layer as described in any one of claims 1 to 7, and a front panel or a touch sensor. An image display is a polarizing plate having an adhesive layer as described in any one of claims 1 to 7.

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