Polarizing film with adhesive layer and image display device

Abstract

A polarizing film with an adhesive layer, wherein the polarizing film has a polarizing film and a first transparent protective film and has a first adhesive layer disposed on the first transparent protective film side of the polarizing film, the polarizing film has a thickness of 20 μm or less, the first adhesive layer is used to adhere to a front surface transparent member disposed on the recognition side of an image display device, and the difference ((A)-(B)) between the saturated moisture content (A) at 80°C and 85% RH and the saturated moisture content (B) at 25°C and 50% RH is 1.0 wt% or more. The polarizing film with an adhesive layer can suppress the decrease in the monomer transmittance of the polarizing film in a high temperature environment.

Description

Technical Field

[0001] The present invention relates to a polarizing film with an adhesive layer and an image display device. Background Art

[0002] Liquid crystal display devices and organic EL display devices are widely used as various image display devices such as mobile phones, smart phones, car navigation devices, computer monitors, and televisions. As polarizing films for these various image display devices, polyvinyl alcohol-based films that have been dyed (containing dichroic substances such as iodine and dichroic dyes) are used from the perspective of both high transmittance and high polarization. The aforementioned polarizing film is usually used in the form of a polarizing film (polarizing plate) with a protective film such as triacetyl cellulose bonded to one or both sides thereof using an adhesive.

[0003] In the above-mentioned various image display devices, in order to prevent the image display panel from being damaged due to impact from the external surface, a transparent front surface transparent plate (also called "cover window", "window layer", etc.) such as a transparent resin plate or a glass plate is sometimes provided on the recognition side of the image display panel. In addition, in recent years, devices having a touch panel on the recognition side of the image display panel have become popular.

[0004] In addition, as a method of configuring a front surface transparent plate, a touch panel or other front surface transparent components on the front surface of the image display panel, an "interlayer filling structure" is proposed in which the image display panel and the front surface transparent component are bonded together with an adhesive layer. Sometimes, an adhesive layer is also provided between the touch panel and the front surface transparent plate. In the interlayer filling structure, since the gaps between the components are filled with the adhesive layer, the refractive index difference at the interface is reduced, and the reduction in visibility caused by reflection and scattering is suppressed. In addition, in the interlayer filling structure, since the components are bonded and fixed by the adhesive layer, the front surface transparent component has the advantage that it is not easy to be peeled off due to impact such as falling, compared with the case where the front surface transparent component is only fixed to the shell.

[0005] On the other hand, among the various image display devices mentioned above, durability at high temperatures is particularly required for in-vehicle displays such as car navigation devices. For example, Patent Documents 1 to 3 state that when an image display device in which an image display unit and a transparent member on the front surface are interlayer-filled with an adhesive is subjected to a long-term high-temperature durability test required for an in-vehicle display, the monomer transmittance in the central part of the plane of the polarizing film constituting the image display panel decreases due to polyeneization of the polyvinyl alcohol constituting the polarizing film under a high-temperature environment. It is particularly pointed out that polyeneization is promoted by the moisture contained in the polarizing film, and there is a tendency that the decrease in monomer transmittance is more significant as the in-plane size of the polarizing film increases.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-75998

[0009] Patent Document 2: Japanese Patent Application Publication No. 2014-102353

[0010] Patent Document 3: Japanese Patent Application Publication No. 2018-101117 Summary of the invention

[0011] Problem that the invention aims to solve

[0012] In the above-mentioned patent document 1, by using an adhesive layer (adhesive sheet) having specific parameters for bonding a front surface transparent component arranged on the identification side of an image display device to a polarizing film, and in addition, in patent document 2, by using a transparent protective film having a specific saturated water absorption, or, in patent document 3, by using an adhesive layer (adhesive sheet) having a specific storage modulus for bonding a transparent resin plate arranged on the identification side of an image display device to a polarizing film, a polarizing film capable of suppressing the decrease in monomer transmittance under high temperature environment can be provided. Although the above disclosure has been made, the present inventors have found that this characteristic can be improved by means different from the above.

[0013] In view of the above circumstances, an object of the present invention is to provide a polarizing film with an adhesive layer capable of suppressing a decrease in the transmittance of the polarizing film alone under a high temperature environment, and an image display device using the polarizing film with an adhesive layer.

[0014] Solutions for solving problems

[0015] That is, the present invention relates to a polarizing film with an adhesive layer, wherein the polarizing film has a polarizing film and a first transparent protective film and has a first adhesive layer arranged on the first transparent protective film side of the polarizing film, the film thickness of the polarizing film is less than 20 μm, the first adhesive layer is used for bonding to a front surface transparent component arranged on the recognition side of an image display device, and the difference ((A)-(B)) between the saturated moisture content (A) at 80°C and 85%RH and the saturated moisture content (B) at 25°C and 50%RH is 1.0 wt% or more.

[0016] In addition, the present invention relates to a polarizing film with an adhesive layer, which comprises a first adhesive layer arranged on the first transparent protective film side of the polarizing film in a polarizing film having a polarizing film and a first transparent protective film, wherein the film thickness of the polarizing film is less than 20 μm, the first adhesive layer is used for bonding to a front surface transparent component arranged on the recognition side of an image display device, and the ratio ((A) / (B)) of the saturated moisture content (A) at 80°C and 85% RH to the saturated moisture content (B) at 25°C and 50% RH is less than 2.5.

[0017] The present invention also relates to an image display device including an image display unit and the front transparent member, wherein the polarizing film with an adhesive layer is bonded to the front transparent member.

[0018] Effects of the Invention

[0019] The details of the mechanism of action of the effect of the pressure-sensitive adhesive layer-attached polarizing film of the present invention are not yet clear, but are presumed as follows. However, the present invention should not be construed as being limited to this mechanism of action.

[0020] The polarizing film with an adhesive layer of the present invention has a first adhesive layer arranged on the first transparent protective film side of the polarizing film in a polarizing film having a polarizing film and a first transparent protective film, the film thickness of the polarizing film is less than 20 μm, the first adhesive layer is used for bonding to a front surface transparent component arranged on the recognition side of an image display device, and the difference ((A)-(B)) between the saturated moisture content (A) at 80°C and 85% RH and the saturated moisture content (B) at 25°C and 50% RH is 1.0 wt% or more. An adhesive layer in which the difference between the saturated moisture content (A) and the saturated moisture content (B) ((A) - (B)) is greater than a certain value, that is, an adhesive layer in which the difference between the saturated moisture content at high temperature and the saturated moisture content near normal temperature is greater than a certain value, can fully absorb moisture released from a polarizing film having a film thickness of less than 20 μm, etc., when the polarizing film with an adhesive layer in an image display device is exposed from near normal temperature to a high temperature environment, thereby preventing the diffusion of moisture in the image display device. It is therefore presumed that it can suppress the decrease in monomer transmittance caused by the polyeneization of the polarizing film in a high temperature environment.

[0021] In addition, the polarizing film with an adhesive layer of the present invention has a first adhesive layer arranged on the first transparent protective film side of the polarizing film in a polarizing film having a polarizing film and a first transparent protective film, the film thickness of the polarizing film is less than 20 μm, the first adhesive layer is used for bonding to a front surface transparent component arranged on the identification side of an image display device, and the ratio ((A) / (B)) of the saturated moisture content (A) at 80°C and 85% RH to the saturated moisture content (B) at 25°C and 50% RH can be less than 2.5. An adhesive layer whose ratio of saturated moisture content (A) to saturated moisture content (B) ((A) / (B)) is below a certain level, that is, an adhesive layer whose ratio of saturated moisture content at high temperature to saturated moisture content near normal temperature is below a certain level, can fully absorb moisture released from a polarizing film having a film thickness of less than 20 μm, etc. when the polarizing film with an adhesive layer in an image display device is exposed from near normal temperature to a high temperature environment, thereby preventing the diffusion of moisture in the image display device. It is therefore presumed that it can suppress the decrease in monomer transmittance caused by polyeneization of the polarizing film in a high temperature environment.

[0022] Although the above-mentioned Patent Documents 1 to 3 point out that the larger the in-plane size of the polarizing film is under high temperature environment, the more significantly the transmittance of the polarizing film decreases, but there is no proof that the transmittance of the polarizing film is reduced when the in-plane size is large (for example, the in-plane size is 300 cm 2 Furthermore, the above patent document does not pay attention to the fact that even when using such a polarizing film with a large in-plane size, in order to suppress polyene formation in a high temperature environment, the difference or ratio between the thickness of the polarizing film and the saturated moisture content in the above-mentioned first adhesive layer (identification side adhesive layer) is also important. On the other hand, the polarizing film with an adhesive layer of the present invention is useful because it can suppress the decrease in monomer transmittance caused by polyene formation of the polarizing film in a high temperature environment by using a polarizing film of less than 20 μm and the above-mentioned first adhesive layer, even when the in-plane size of the polarizing film is large. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic cross-sectional view showing a structural example of a polarizing film with an adhesive layer.

[0024] Figure 2 It is a schematic cross-sectional view showing a configuration example of an image display device using a polarizing film with an adhesive layer. DETAILED DESCRIPTION

[0025] Figure 1Schematic cross-sectional view showing a configuration example of a polarizing film with an adhesive layer of the present invention. The polarizing film 10 has at least a polarizing film 11 and a first transparent protective film 12, and the polarizing film 100 with an adhesive layer has a first adhesive layer 20 on the first transparent protective film 12 side of the polarizing film 10. In addition, the polarizing film 10 may have a second transparent protective film and a second adhesive layer 30 on the opposite side of the polarizing film 10 having the first transparent protective film 12. As required, a separator 45 and a separator 46 may be attached to the first adhesive layer 20 and the second adhesive layer 30 in a releasable manner, respectively.

[0026] Figure 2 Schematic cross-sectional view showing a configuration example of an image display device using a polarizing film with an adhesive layer of the present invention. In the image display device 110, a front surface transparent member 70 is bonded to a polarizing film 10 via a first adhesive layer 20, and an image display unit 90 is bonded to a polarizing film 10 via a second adhesive layer 30. It should be noted that the front surface transparent member 70 may have a printed step 72 at the peripheral portion of the front surface transparent plate 71.

[0027] The adhesive layer 20 is a so-called "interlayer filler" which, in addition to fixing the polarizing film 10 and the front surface transparent member 70, has the function of reducing the refractive index difference at the interface and suppressing the reduction in visibility caused by reflection and scattering of light. In addition, the interlayer filler also has the function of serving as a buffer layer to resist impact and compression from the external surface to the image display unit 90 such as the liquid crystal unit.

[0028] <Polarizing film with adhesive layer (single-sided protective polarizing film with adhesive layer)>

[0029] The pressure-sensitive adhesive layer-attached polarizing film (pressure-sensitive adhesive layer-attached single-sided protective polarizing film) of the present invention comprises a polarizing film and a first transparent protective film and includes a first pressure-sensitive adhesive layer provided on the first transparent protective film side of the polarizing film.

[0030] <Polarizing film>

[0031] The polarizing film of the present invention is an iodine-based polarizing film formed by adsorbing and orienting iodine in a polyvinyl alcohol-based film, and the film thickness is 20 μm or less. When the polarizing film of the present invention has a film thickness greater than 20 μm, the amount of water contained in the polarizing film tends to increase, and thus it is impossible to suppress the deterioration of the polarizing film having a large in-plane size (e.g., an in-plane size of 300 cm) under a high temperature environment (e.g., 95°C, 500 hours). 2 The above) polarizing film is not preferred because it reduces the transmittance of the polarizing film alone.

[0032] The polyvinyl alcohol-based film can be used without particular limitation as long as it is a film that is light-transmissive in the visible light region and disperses and adsorbs iodine. As the material of the polyvinyl alcohol-based film, polyvinyl alcohol or its derivatives can be listed. As the derivatives of the polyvinyl alcohol, for example, polyvinyl formal, polyvinyl acetal; olefins such as ethylene and propylene; products modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and their alkyl esters, acrylamide, etc. can be listed. The average degree of polymerization of the polyvinyl alcohol is preferably about 100 to 10,000, more preferably about 1,000 to 10,000, and further preferably about 1,500 to 4,500. In addition, the saponification degree of the polyvinyl alcohol is preferably about 80 to 100 mol%, more preferably about 95 mol% to 99.95 mol. It should be noted that the average degree of polymerization and the saponification degree can be obtained according to JIS K 6726.

[0033] The polarizing film can be manufactured by a known method, usually by dyeing a polyvinyl alcohol film with iodine and stretching it. In particular, the manufacture of a thin polarizing film with a thickness of 10 μm or less can be manufactured by a known method for manufacturing a thin polarizing film, which includes a step of stretching a polyvinyl alcohol resin layer and a stretching resin substrate in a laminated state, and a step of dyeing with iodine.

[0034] In the aforementioned polarizing film with an adhesive layer, the in-plane size of the polarizing film is not particularly limited. In the polarizing film with an adhesive layer of the present invention, from the perspective of suppressing the decrease in monomer transmittance caused by polyeneization under a high temperature environment even when the in-plane size of the polarizing film is large, the in-plane size of the polarizing film may be 150 cm 2 Above, can be 300cm 2 Above, can be 600cm 2 Above, or can be 900cm 2 It should be noted that the in-plane dimensions of the polarizing film are usually the same as the in-plane dimensions of the polarizing membrane.

[0035] <First transparent protective film>

[0036] The first transparent protective film of the present invention is not particularly limited, and various transparent protective films used for polarizing films can be used. As the material constituting the aforementioned first transparent protective film, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. can be used. As the aforementioned thermoplastic resin, for example, cellulose ester resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone resins, polysulfone resins, polycarbonate resins, nylon, polyamide resins such as aromatic polyamide, polyimide resins, polyethylene, polypropylene, ethylene / propylene copolymers and the like polyolefin resins, (meth) acrylic resins, cyclic polyolefin resins (norbornene resins) having a ring system or norbornene structure, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof can be cited. In addition, the first transparent protective film may be a cured layer formed of a thermosetting resin or ultraviolet curing resin such as a (meth) acrylic resin, a urethane resin, an acrylic urethane resin, an epoxy resin, or a silicone resin, among which cellulose ester resins, polycarbonate resins, (meth) acrylic resins, cyclic polyolefin resins, and polyester resins are preferred.

[0037] The thickness of the first transparent protective film can be appropriately determined, and is usually preferably about 1 to 500 μm, more preferably about 1 to 300 μm, and even more preferably about 5 to 100 μm from the viewpoints of strength, handling properties such as ease of handling, and thinness.

[0038] From the viewpoint of allowing the water in the polarizing film to diffuse out of the system and suppressing the decrease in the monomer transmittance of the polarizing film caused by polyeneization, the water vapor permeability of the first transparent protective film is preferably 100 g / m 2 24h or more, more preferably 200g / m 2 24h or more, more preferably 300g / m 2 ·24h or more, and from the perspective of improving the humidification durability of the polarizing film, the moisture permeability is preferably 1600g / m 2 24h or less, more preferably 1300g / m 2 Less than 24 hours. It should be noted that the moisture permeability can be calculated by placing a sample cut into a diameter of 60 mm in a moisture permeability cup containing about 15 g of calcium chloride and placing it in a constant temperature machine at a temperature of 40°C and a humidity of 90% RH according to the moisture permeability test (cup method) of JIS Z0208, and measuring the weight increase of calcium chloride before and after 24 hours.

[0039] The polarizing film and the first transparent protective film are usually bonded by means of an adhesive layer. As the adhesive forming the adhesive layer, various adhesives used for polarizing films can be applied, for example, isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex systems, water-based polyesters, etc. can be listed. These adhesives are usually used in the form of adhesives formed by aqueous solutions, containing 0.5 to 60% by weight of solid content. In addition, as the aforementioned adhesive, in addition to the above, active energy ray-curing adhesives such as ultraviolet curing adhesives and electron beam curing adhesives can be listed. As the aforementioned active energy ray-curing adhesive, for example, (meth) acrylate adhesives can be listed. As the curable component in the aforementioned (meth) acrylate adhesive, for example, compounds having (meth) acryloyl groups and compounds having vinyl groups can be listed. In addition, compounds having epoxy groups and oxetane groups can also be used as cationic polymerization curing adhesives. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various commonly known curable epoxy compounds can be used. The thickness of the adhesive layer is not particularly limited, and is preferably about 30 to 5000 nm, more preferably about 100 to 1000 nm, when using a water-based adhesive, etc., and is preferably about 0.1 to 100 μm, more preferably about 0.5 to 10 μm, when using an ultraviolet curing adhesive, an electron beam curing adhesive, etc.

[0040] <First adhesive layer (identification side adhesive layer)>

[0041] The first adhesive layer of the present invention is used for bonding to the front surface transparent component arranged on the identification side of the image display device, and the difference ((A)-(B)) between the saturated moisture content (A) at 80°C and 85% RH and the saturated moisture content (B) at 25°C and 50% RH is 1.0 wt% or more. Alternatively, the first adhesive layer of the present invention is used for bonding to the front surface transparent component arranged on the identification side of the image display device, and the ratio ((A) / (B)) between the saturated moisture content (A) at 80°C and 85% RH and the saturated moisture content (B) at 25°C and 50% RH is 2.5 or less. The aforementioned first adhesive layer is an adhesive sheet formed by an adhesive.

[0042] From the perspective of a front surface transparent component for bonding to the identification side of an image display device, the thickness of the first adhesive layer is usually more than 50 μm. From the perspective of preventing the occurrence of bubbles caused by foreign matter in a high temperature environment (e.g., 95°C, 500 hours), increasing the amount of moisture absorption, and step absorbability, the thickness is preferably more than 150 μm, more preferably more than 200 μm. From the perspective of productivity, etc., the thickness is preferably less than 600 μm, more preferably less than 500 μm, and further preferably less than 400 μm.

[0043] As the aforementioned front surface transparent member configured on the identification side of the image display device, for example, a front surface transparent plate (also called "cover window", "window layer", etc.), a touch panel, etc. can be listed. As the aforementioned front surface transparent plate, a transparent plate with appropriate mechanical strength and thickness can be used. As such a transparent plate, for example, a transparent resin plate or a glass plate such as an acrylic resin or a polycarbonate resin can be used. As the aforementioned touch panel, for example, various touch panels such as an impedance film type, a capacitive type, an optical type, an ultrasonic type, a glass plate with a touch sensing function, a transparent resin plate, etc. can be used. In the case of using a capacitive touch panel as the aforementioned front surface transparent member, it is preferred to set a front surface transparent plate formed of glass or a transparent resin plate closer to the identification side than the touch panel.

[0044] The difference ((A)-(B)) between the saturated moisture content (A) at 80°C and 85% RH and the saturated moisture content (B) at 25°C and 50% RH of the first adhesive layer is 1.0 wt% or more. When the difference ((A)-(B)) between the saturated moisture content (A) and the saturated moisture content (B) of the first adhesive layer is less than 1.0 wt%, it is not preferred because the decrease in the monomer transmittance of the polarizing film in a high temperature environment (e.g., 95°C and 500 hours) cannot be suppressed. The difference ((A)-(B)) between the saturated moisture content (A) and the saturated moisture content (B) of the first adhesive layer is preferably 1.1 wt% or more, more preferably 1.3 wt% or more, and from the perspective of the change in the dielectric constant under a humidified environment, it is preferably 5.0 wt% or less, more preferably 4.0 wt% or less. Alternatively, the ratio of the saturated moisture content (A) at 80°C and 85% RH to the saturated moisture content (B) at 25°C and 50% RH ((A) / (B)) of the first adhesive layer is 2.5 or less. When the ratio ((A) / (B)) of the saturated moisture content (A) to the saturated moisture content (B) of the first adhesive layer is greater than 2.5, it is not preferred because the decrease in the monomer transmittance of the polarizing film in a high temperature environment (e.g., 95°C and 500 hours) cannot be suppressed. From the perspective of humidified turbidity, the ratio ((A) / (B)) of the saturated moisture content (A) to the saturated moisture content (B) of the first adhesive layer is preferably greater than 1.0, more preferably greater than 2.0, and preferably less than 2.4. It should be noted that from the perspective that when the saturated moisture content is too low, moisture cannot be fully absorbed; and when the saturated moisture content is too high, the amount of moisture absorbed increases, and components in the adhesive layer seep out and have an adverse effect, the saturated moisture content (A) is preferably about 1.5 to 3.0% by weight, more preferably about 2.0 to 2.5% by weight, and the saturated moisture content (B) is preferably about 0 to 3.0% by weight, more preferably about 0.5 to 2.0% by weight.

[0045] The first adhesive layer preferably has high transparency. The first adhesive layer preferably has a haze value of 1% or less and a total light transmittance of 90% or more. The haze value and total light transmittance are measured using a haze meter in accordance with JIS K7136.

[0046] The adhesive (adhesive composition) forming the aforementioned first adhesive layer is not limited as long as it satisfies the above-mentioned difference in saturated moisture content. From the perspective of excellent optical transparency, moderate adhesive properties such as wettability, cohesion and adhesion, and excellent weather resistance, heat resistance, etc., an acrylic adhesive containing an acrylic polymer as a base polymer is preferred.

[0047] The acrylic polymer has a monomer unit of alkyl (meth)acrylate as the main skeleton. It should be noted that in this specification, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid. In the case where the base polymer is a copolymer, the arrangement of the constituent monomers can be random or block.

[0048] As the aforementioned alkyl (meth)acrylate, for example, there can be mentioned an alkyl (meth)acrylate having an alkyl group with a carbon number of 1 to 20. The aforementioned alkyl group may be a linear or branched alkyl group, or may be a cyclic cycloalkyl group. From the perspective of easily controlling the difference ((A)-(B)) between the saturated moisture content (A) and the saturated moisture content (B) in the adhesive layer to be 1.0 weight % or more, or from the perspective of easily controlling the ratio ((A) / (B)) of the saturated moisture content (A) to the saturated moisture content (B) to be 2.5 or less, the aforementioned alkyl (meth)acrylate preferably uses an alkyl (meth)acrylate having a linear or branched alkyl group with a carbon number of 8 or less, more preferably uses an alkyl (meth)acrylate having a linear or branched alkyl group with a carbon number of 6 or less, and more preferably uses an alkyl (meth)acrylate having a linear or branched alkyl group with a carbon number of 4 or less. The aforementioned alkyl (meth)acrylate may be used alone or in combination of two or more.

[0049] In addition, from the perspective of easily controlling the difference ((A)-(B)) between the saturated moisture content (A) and the saturated moisture content (B) in the adhesive layer to be 1.0% by weight or more, or from the perspective of easily controlling the ratio ((A) / (B)) between the saturated moisture content (A) and the saturated moisture content (B) to be 2.5 or less, the alkyl (meth)acrylate is preferably used in combination with an alkyl (meth)acrylate having a linear or branched alkyl group and an alkyl (meth)acrylate having a cyclic cycloalkyl group. In this case, the weight ratio of the alkyl (meth)acrylate having a linear or branched alkyl group to the alkyl (meth)acrylate having a cyclic cycloalkyl group (alkyl (meth)acrylate having a linear or branched alkyl group / alkyl (meth)acrylate having a cyclic cycloalkyl group) is preferably 70 / 30 to 95 / 5, and more preferably 80 / 20 to 92 / 8.

[0050] The proportion of the alkyl (meth)acrylate in the total amount of the monomer components constituting the acrylic polymer is preferably 40% by weight or more, more preferably 50% by weight or more, and even more preferably 60% by weight or more.

[0051] From the perspective of easily controlling the difference ((A) - (B)) between the saturated moisture content (A) and the saturated moisture content (B) in the adhesive layer to be greater than 1.0 wt % or easily controlling the ratio ((A) / (B)) of the saturated moisture content (A) to the saturated moisture content (B) to be less than 2.5, the acrylic polymer preferably contains a polar monomer in addition to the (meth)acrylic acid alkyl ester. As polar monomers, for example, nitrogen-containing monomers such as N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, (meth)acryloylmorpholine, N-vinylcarboxylic acid amides, and N-vinylcaprolactam can be listed; hydroxyl-containing monomers such as hydroxyl (meth) acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. In particular, as polar monomers, the aforementioned hydroxyl-containing monomers are preferably used. The aforementioned polar monomers can be used alone or in combination of two or more.

[0052] The proportion of the polar monomer in the total amount of the monomer components constituting the acrylic polymer is preferably 15 wt % or more, more preferably 20 wt % or more, further preferably 30 wt % or more, and is preferably 60 wt % or less, more preferably 50 wt % or less, further preferably 40 wt % or less.

[0053] As the monomer component constituting the acrylic polymer, in addition to the monomers exemplified above, other comonomers may be used within the range not impairing the effects of the present invention. Examples of the other comonomers include amino-containing monomers, epoxy-containing monomers, aromatic vinyl-based monomers, and the like.

[0054] The ratio of the total of the (meth)acrylate and the polar monomer to the total of the monomer components constituting the acrylic polymer is preferably 70 wt % or more, more preferably 80 wt % or more, further preferably 90 wt % or more, and even more preferably 95 wt % or more.

[0055] The acrylic polymer can be prepared by polymerizing the above-mentioned monomer components by a known polymerization method. Examples of the polymerization method of the acrylic polymer include solution polymerization, emulsion polymerization, bulk polymerization, polymerization by active energy ray irradiation (active energy ray polymerization), etc. In terms of transparency, water resistance, cost, etc., solution polymerization or active energy ray polymerization is preferred.

[0056] When preparing the acrylic polymer, a polymerization initiator such as a photopolymerization initiator or a thermal polymerization initiator may be used according to the type of polymerization reaction. The molecular weight of the acrylic polymer may be appropriately adjusted. In order to make the adhesive layer have appropriate viscoelasticity and adhesion, the polystyrene-equivalent weight average molecular weight of the acrylic polymer is preferably about 50,000 to 2,000,000, and more preferably about 100,000 to 1,500,000.

[0057] The ratio of the acrylic polymer in the solid content of the acrylic pressure-sensitive adhesive is preferably 70% by weight or more, more preferably 80% by weight or more, further preferably 90% by weight or more, and further preferably 95% by weight or more.

[0058] The aforementioned adhesive layer can have a cross-linked structure as required. The formation of the cross-linked structure can be, for example, by adding a cross-linking agent to the adhesive. As the aforementioned cross-linking agent, for example, commonly used cross-linking agents such as isocyanate cross-linking agents, epoxy cross-linking agents, oxazoline cross-linking agents, aziridine cross-linking agents, carbodiimide cross-linking agents, and metal chelate cross-linking agents can be used. From the perspective of the situation where the adhesion to the adherend decreases due to the decrease in the softness (fluidity) of the adhesive, the generation of bubbles mixed in or uneven display caused by the printing step of the front surface transparent component, relative to 100 parts by weight of the aforementioned acrylic polymer, the content of the aforementioned cross-linking agent is generally less than 10 parts by weight, preferably less than 5 parts by weight, and more preferably less than 3 parts by weight. The aforementioned cross-linking agent can be used alone or in combination of two or more.

[0059] In order to adjust the adhesive strength, a silane coupling agent may be added to the adhesive. When the silane coupling agent is used, the amount of the silane coupling agent is generally about 0.01 to 5 parts by weight, preferably about 0.03 to 2 parts by weight, relative to 100 parts by weight of the acrylic polymer. The silane coupling agent may be used alone or in combination of two or more.

[0060] From the perspective of controlling the difference ((A)-(B)) between the saturated moisture content (A) and the saturated moisture content (B) in the adhesive layer or the ratio ((A) / (B)) of the saturated moisture content (A) and the saturated moisture content (B), the adhesive may contain a hygroscopic substance. Examples of the hygroscopic substance include zeolite and the like.

[0061] A tackifier may be added to the adhesive as required. Examples of the tackifier include terpene tackifiers, styrene tackifiers, phenol tackifiers, rosin tackifiers, epoxy tackifiers, dicyclopentadiene tackifiers, polyamide tackifiers, ketone tackifiers, and elastic tackifiers.

[0062] The adhesive may contain additives such as a plasticizer, a softener, an anti-degradation agent, a filler, a colorant, an ultraviolet absorber, an antioxidant, a surfactant, and an antistatic agent within a range that does not impair the properties of the adhesive.

[0063] The aforementioned adhesive layer is formed by the aforementioned adhesive. The aforementioned adhesive may be an adhesive composition having any form, for example, an emulsion type, a solvent type (solution type), an active energy ray curing type, a hot melt type (hot melt type), etc. As the adhesive, preferably, a solvent type adhesive and an active energy ray curing type (photocuring type) adhesive may be listed. As the aforementioned solvent type adhesive, preferably, an adhesive containing the aforementioned (meth) acrylic polymer as an essential component may be listed. In addition, as the aforementioned active energy ray curing type adhesive, preferably, an adhesive containing a mixture (monomer mixture) of monomer components constituting the aforementioned (meth) acrylic polymer or a partial polymer thereof as an essential component may be listed. From the perspective of controlling the timing of curing, productivity, etc., the aforementioned adhesive is preferably an active energy ray curing type (photocuring type) adhesive.

[0064] The active energy ray-curable (photocurable) adhesive contains a photocurable component in addition to a mixture (monomer mixture) of monomer components constituting the aforementioned (meth) acrylic polymer or a partial polymer thereof. As a photocurable compound, for example, a polyfunctional polymerizable compound having two or more polymerizable functional groups in one molecule can be preferably used. As a polyfunctional polymerizable compound, for example, compounds having two or more C=C bonds in one molecule, compounds having one C=C bond and polymerizable functional groups such as epoxy, aziridine, oxazoline, hydrazine, hydroxymethyl, etc. can be listed. From the perspective of flexibility and adhesion, the mixing ratio of the aforementioned photocurable component is preferably 7 parts by weight or less, more preferably 5 parts by weight or less, and further preferably 3 parts by weight or less, relative to 100 parts by weight of the total monomer components constituting the acrylic polymer.

[0065] As methods for forming the aforementioned adhesive layer, for example, there can be listed a method of applying the aforementioned solvent-based adhesive to a release film, etc., and drying and removing the polymerization solvent, etc. to form an adhesive layer; a method of applying the aforementioned solvent-based adhesive to a polarizing film, etc., and drying and removing the polymerization solvent, etc. to form an adhesive layer on the polarizing film, etc.; a method of applying an active energy ray-curable adhesive to a release film, etc., and forming it by irradiating it with active energy rays, etc.

[0066] <Polarizing film with adhesive layer (double-sided protective polarizing film with adhesive layer)>

[0067] In the polarizing film with an adhesive layer (double-sided protective polarizing film with an adhesive layer) of the present invention, the polarizing film has a second transparent protective film provided on the side of the polarizing film opposite to the side having the first transparent protective film.

[0068] <Second transparent protective film>

[0069] The second transparent protective film of the present invention is not particularly limited, and an example thereof may be a film of the first transparent protective film. In view of the production efficiency of the drying process after laminating the polarizing film and the transparent protective film, the moisture permeability of the second transparent protective film is preferably 1 g / m 2 24h or more, more preferably 5g / m 2 24h or more, more preferably 10g / m 2 · 24 hours or more, and from the perspective of absorbing moisture in the polarizing film under high temperature environment into the first adhesive layer, the moisture permeability is preferably 200g / m 2 24h or less, more preferably 180g / m 2 24h or less, more preferably 150g / m 2 · 24 hours or less. It should be noted that the polarizing film and the second transparent protective film are usually bonded together via the adhesive layer.

[0070] The first transparent protective film and / or the second transparent protective film may use a phase difference plate having a front phase difference of 40 nm or more and / or a thickness direction phase difference of 80 nm or more. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. In the case of using a phase difference plate as the transparent protective film, since the phase difference plate also acts as a transparent protective film, thinning can be achieved.

[0071] As the aforementioned phase difference plate, for example, a birefringent film formed by unidirectional or bidirectional stretching of a polymer raw material, an oriented film of a liquid crystal polymer, a plate formed by supporting an oriented layer of a liquid crystal polymer with a film, etc. can be cited. The thickness of the phase difference plate is not particularly limited, and is usually about 20 to 150 μm. It should be noted that the aforementioned phase difference plate can be bonded to a transparent protective film without a phase difference for use.

[0072] The first transparent protective film and / or the second transparent protective film may contain any appropriate additives such as ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, antistatic agents, pigments, colorants, etc.

[0073] On the surface of the polarizing film not attached with the first transparent protective film and / or the second transparent protective film, a functional layer such as a hard coating layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer, an anti-glare layer, etc. may be provided. It should be noted that the functional layer such as the hard coating layer, the anti-reflection layer, the anti-adhesion layer, the diffusion layer, or the anti-glare layer may be provided as the protective film itself, or may be provided as other films different from the protective film.

[0074] The first transparent protective film and / or the second transparent protective film and the polarizing film, or the polarizing film and the functional layer may be laminated via intervening layers such as a surface modification layer, an adhesive layer, a barrier layer, and a refractive index adjustment layer.

[0075] Examples of the surface modification treatment for forming the surface modification layer include corona treatment, plasma treatment, primer treatment, and saponification treatment.

[0076] Examples of the easy-adhesive agent forming the easy-adhesive layer include materials formed from various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone skeleton, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like.

[0077] The barrier layer is a layer that has the function of preventing impurities such as oligomers and ions dissolved from the transparent protective film from migrating (invading) into the polarizing film. The barrier layer can be any layer as long as it has transparency and can prevent impurities dissolved from the transparent protective film. Examples of materials for forming the barrier layer include urethane prepolymer-based materials, cyanoacrylate-based materials, and epoxy-based materials.

[0078] The refractive index adjusting layer is a layer provided to suppress the decrease in transmittance due to reflection between layers with different refractive indices such as the transparent protective film and the polarizing film. As the refractive index adjusting material forming the refractive index adjusting layer, for example, materials including various resins and additives such as silica, acrylic, acrylic-styrene, and melamine can be cited.

[0079] <Second Adhesive Layer (Cell-Side Adhesive Layer)>

[0080] In the polarizing film with an adhesive layer (double-sided protective polarizing film with an adhesive layer) of the present invention, the polarizing film has a second adhesive layer, and the second adhesive layer is provided on the side of the polarizing film having the second transparent protective film.

[0081] As the adhesive (adhesive composition) forming the aforementioned second adhesive layer, various adhesives used for polarizing films can be applied, and an adhesive using acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy-based, fluorine-based, natural rubber, synthetic rubber and other rubber-based polymers as base polymers can be appropriately selected and used. In particular, acrylic adhesives containing acrylic polymers as base polymers can be preferably used from the perspective of excellent optical transparency, moderate adhesive properties such as wettability, cohesion and adhesion, and excellent weather resistance, heat resistance, etc.

[0082] The thickness of the second adhesive layer is not particularly limited, but is preferably about 3 μm to 35 μm, more preferably 5 μm to 32 μm, and even more preferably 10 μm to 30 μm from the viewpoint of adhesion and handling properties.

[0083] The first adhesive layer and / or the second adhesive layer preferably have a low content of organic acid monomers (free organic acid) such as (meth) acrylic acid. By reducing the organic acid monomer content of the first adhesive layer, the decrease in the monomer transmittance of the polarizing plate caused by polyeneization can be suppressed. The (meth) acrylic acid monomer content in the adhesive layer is preferably less than 100 ppm, more preferably less than 70 ppm, and further preferably less than 50 ppm. The organic acid monomer content of the adhesive layer is obtained by immersing the adhesive layer in pure water, heating at 100°C for 45 minutes, and quantifying the acid monomer extracted into the water by an ion chromatograph.

[0084] Usually, in the polymer of thermosetting type, light-curing type, there are unreacted residual monomers inevitably.Therefore, in order to reduce the acid monomer content in the adhesive layer, it is preferred to reduce the amount of organic acid monomer components such as (methyl) acrylic acid in the monomer component constituting the base polymer.The base polymer preferably does not contain organic acid monomer (carboxyl group-containing monomer) as monomer unit in fact.In the sum of the monomer component constituting the acrylic acid-based polymer, the carboxyl group-containing monomer is preferably below 0.5 wt %, more preferably below 0.1 wt %, further preferably below 0.05 wt %.

[0085] On the aforementioned first adhesive layer and / or the aforementioned second adhesive layer, a release film can be attached in a removable manner as needed. As the constituent material of the release film, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film can be suitably used. The substrate used in the formation of the adhesive layer (coating of the adhesive) can also be directly used as a release film for the adhesive layer. By appropriately applying a release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment to the surface of the release film, the peelability from the adhesive layer can be improved when it is used in practical applications.

[0086] <Image display device>

[0087] The image display device of the present invention comprises an image display unit and the front transparent member, and the polarizing film with an adhesive layer is bonded to the front transparent member.

[0088] As the aforementioned image display unit, for example, a liquid crystal unit, an organic EL unit, etc. can be listed. As the aforementioned liquid crystal unit, for example, any one of a reflective liquid crystal unit using external light, a transmissive liquid crystal unit using light from a light source such as a backlight, and a semi-transmissive and semi-reflective liquid crystal unit using both light from the outside and light from the light source can be used. In the case where the aforementioned liquid crystal unit uses light from a light source, the image display device (liquid crystal display device) is also provided with a polarizing film on the opposite side of the recognition side of the image display unit (liquid crystal unit), and further provided with a light source. The polarizing film on the light source side is preferably bonded to the liquid crystal unit by means of an appropriate adhesive layer. As the driving mode of the aforementioned liquid crystal unit, for example, any type such as VA mode, IPS mode, TN mode, STN mode, bent orientation (π type) can be used.

[0089] As the organic EL unit, for example, an organic EL unit in which a transparent electrode, an organic light-emitting layer and a metal electrode are sequentially stacked on a transparent substrate to form a light-emitting body (organic electroluminescent light-emitting body) can be suitably used. The organic light-emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer formed of a triphenylamine derivative or the like and a light-emitting layer formed of a fluorescent organic solid such as anthracene, a laminate of these light-emitting layers and an electron injection layer formed of a perylene derivative or the like, or a laminate of a hole injection layer, a light-emitting layer and an electron injection layer can be used.

[0090] The pressure-sensitive adhesive layer-attached polarizing film of the present invention has an excellent effect of suppressing a decrease in monomer transmittance due to polyeneization of the polarizing film under high temperature conditions and is therefore suitably used in vehicle-mounted image display devices such as car navigation devices and rear displays.

[0091] Example

[0092] The present invention is further described in detail with reference to the following examples, but the present invention is not limited to these examples.

[0093] <Preparation of first adhesive layer>

[0094] <Adhesive layer A>

[0095] A monomer mixture consisting of 60 parts by weight of butyl acrylate (BA), 6 parts by weight of cyclohexyl acrylate (CHA), 26 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 8 parts by weight of hydroxyethyl acrylate (HEA), as well as 0.09 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Co., Ltd.) and 0.09 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan Co., Ltd.) were placed in a four-necked flask and exposed to ultraviolet rays in a nitrogen atmosphere to cause partial photopolymerization, thereby obtaining a partial polymer (monomer syrup) with a polymerization rate of about 10%. To 100 parts by weight of the partial polymer, 0.12 parts by weight of dipentaerythritol hexaacrylate ("KAYARAD DPHA" manufactured by Nippon Kayaku Co., Ltd.) as a multifunctional polymerizable compound and 0.3 parts by weight of 3-glycidoxypropyltrimethoxysilane ("KBM-403" manufactured by Shin-Etsu Chemical) as a silane coupling agent were added and uniformly mixed to prepare an adhesive (adhesive composition). The obtained adhesive was applied to the release-treated surface of a release film (a type in which a release treatment was applied to one side of a polyethylene terephthalate film, with a thickness of 38 μm, trade name "MRF38", manufactured by Mitsubishi Resins Co., Ltd.) to form a coating layer, and a similar release film was also provided on the coating layer. Next, the film was irradiated with black light at an intensity of 5 mW / cm 2 The ultraviolet light is used to polymerize until the accumulated light reaches 3600mJ / cm 2 , a first adhesive layer with a release film on both sides was prepared. It should be noted that the thickness of the first adhesive layer was set to the thickness shown in Table 1 by adjusting the coating amount.

[0096] <Adhesive layer B>

[0097] A monomer mixture consisting of 67 parts by weight of 2-ethylhexyl acrylate (2EHA), 15 parts by weight of N-vinyl-2-pyrrolidone (NVP), 3 parts by weight of 2-hydroxyethyl acrylate (HEA), 15 parts by weight of 4-hydroxybutyl acrylate (4HBA), 0.035 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Co., Ltd.) and 0.035 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan Co., Ltd.) was placed in a four-necked flask and exposed to ultraviolet rays in a nitrogen atmosphere to cause partial photopolymerization, thereby obtaining a partial polymer (monomer syrup) with a polymerization rate of about 10%. To 100 parts by weight of the partial polymer, 0.3 parts by weight of 1,6-hexanediol diacrylate ("NK Ester A-HD-N" manufactured by Shin-Nakamura Chemical Co., Ltd.) as a multifunctional polymerizable compound and 0.3 parts by weight of 3-glycidoxypropyltrimethoxysilane ("KBM-403" manufactured by Shin-Etsu Chemical) as a silane coupling agent were added and uniformly mixed to prepare an adhesive (adhesive composition). The obtained adhesive was applied to the release-treated surface of a release film (a type in which a release treatment was applied to one side of a polyethylene terephthalate film, with a thickness of 38 μm, trade name "MRF38", manufactured by Mitsubishi Resins Co., Ltd.) to form a coating layer, and a similar release film was also provided on the coating layer. Next, the film was irradiated with black light at an intensity of 5 mW / cm 2 The ultraviolet light is used to polymerize until the accumulated light reaches 3600mJ / cm 2 , a first adhesive layer with a release film on both sides was prepared. It should be noted that the thickness of the first adhesive layer was set to the thickness shown in Table 1 by adjusting the coating amount.

[0098] <Adhesive layer C>

[0099] A monomer mixture consisting of 40 parts by weight of 2-ethylhexyl acrylate (2EHA), 40 parts by weight of isostearyl acrylate (ISTA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), 0.05 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Co., Ltd.), and 0.05 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan Co., Ltd.) was placed in a four-necked flask and exposed to ultraviolet rays in a nitrogen atmosphere to cause partial photopolymerization, thereby obtaining a partial polymer (monomer syrup) with a polymerization rate of about 10%. To 100 parts by weight of the partial polymer, 0.02 parts by weight of trimethylolpropane triacrylate ("TMP3A" manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a multifunctional polymerizable compound and 0.3 parts by weight of 3-glycidoxypropyltrimethoxysilane ("KBM-403" manufactured by Shin-Etsu Chemical) as a silane coupling agent were added and uniformly mixed to prepare an adhesive (adhesive composition). The obtained adhesive was applied to the release-treated surface of a release film (a type in which a release treatment was applied to one side of a polyethylene terephthalate film, with a thickness of 38 μm, trade name "MRF38", manufactured by Mitsubishi Resins Co., Ltd.) to form a coating layer, and a similar release film was also provided on the coating layer. Next, the film was irradiated with black light at an intensity of 5 mW / cm 2 The ultraviolet light is used to polymerize until the accumulated light reaches 3600mJ / cm 2 , a first adhesive layer with a release film on both sides was prepared. It should be noted that the thickness of the first adhesive layer was set to the thickness shown in Table 1 by adjusting the coating amount.

[0100] <Example 1>

[0101] <Preparation of polarizing film>

[0102] <Polarizing Film A>

[0103] A polyvinyl alcohol film having an average degree of polymerization of 2400, a saponification degree of 99.9 mol %, and a thickness of 45 μm was prepared. The polyvinyl alcohol film was immersed in a swelling bath (water bath) at 20° C. for 30 seconds between rollers with different peripheral speed ratios to swell while being stretched to 2.2 times in the conveying direction (swelling process), and then, while being immersed in a dyeing bath (an aqueous solution having an iodine concentration of 0.1 wt % and a potassium iodide concentration of 0.9 wt %) at 30° C. for dyeing, the film was stretched to 3.3 times in the conveying direction based on the original polyvinyl alcohol film (a polyvinyl alcohol film that was not stretched in the conveying direction at all) (dyeing process). Next, the dyed polyvinyl alcohol film was immersed in a crosslinking bath (an aqueous solution having a boric acid concentration of 3.0 wt % and a potassium iodide concentration of 3.0 wt %) at 40° C. for 28 seconds and stretched to 3.6 times in the conveying direction based on the original polyvinyl alcohol film (crosslinking process). Furthermore, the obtained polyvinyl alcohol film was immersed in a stretching bath (boric acid concentration of 4.0 wt % and potassium iodide concentration of 5.0 wt %) at 61°C for 60 seconds and stretched to 6.0 times along the conveying direction based on the original polyvinyl alcohol film (stretching process), and then immersed in a cleaning bath (potassium iodide concentration of 2.0 wt %) at 20°C for 10 seconds (cleaning process). The cleaned polyvinyl alcohol film was dried at 40°C for 30 seconds to prepare a polarizing film. The iodine content determined by the following measurement method was 2.8 wt %. In addition, the thickness of the polarizing film was 18 μm.

[0104] [Method for measuring iodine concentration (weight %) in polarizing film]

[0105] The diameter of the polarizing film was measured using a fluorescent X-ray analyzer (manufactured by Rigaku Corporation, trade name "ZSX-PRIMUSIV"): )The iodine concentration (weight %) is calculated by the following formula.

[0106] Iodine concentration (wt%) = 14.474 × (fluorescent X-ray intensity) / (thickness of film) (kcps / μm) It should be noted that the coefficient used in calculating the concentration varies depending on the measuring device, but the coefficient can be obtained using an appropriate calibration curve.

[0107] <Preparation of polarizing film with adhesive layer>

[0108] As an adhesive, an aqueous solution containing a polyvinyl alcohol resin containing an acetoacetyl group (average degree of polymerization of 1200, saponification degree of 98.5 mol%, and degree of acetoacetylation of 5 mol%) and methylol melamine in a weight ratio of 3:1 was used. Using this adhesive, a transparent protective film with a thickness of 30 μm (manufactured by Nippon Shokubai, with a moisture permeability of 125 g / (m 2 ·24h)) as the second transparent protective film, and on the other side (identification side) a triacetyl cellulose film (manufactured by Fuji Film, trade name "TJ40UL") was laminated with a transparent protective film having a thickness of 49 μm (moisture permeability of 300 g / (m 2 ·24h)) as the first transparent protective film, and then continue to heat and dry in an oven (temperature of 90°C, time of 10 minutes) to prepare a polarizing film with transparent protective films laminated on both sides of the polarizing film. The monomer transmittance of the polarizing film is 41.7%. Next, the isolation film with the first adhesive layer provided with isolation films on both sides obtained above is peeled off, and the adhesive layer is laminated to the first transparent protective film of the obtained polarizing film to prepare a polarizing film with an adhesive layer.

[0109] [Method for measuring saturated moisture content]

[0110] The first adhesive layer obtained above was cut into 1cm×1cm, the isolation film was peeled off, and it was pasted on the aluminum foil to make an evaluation sample. The weight (W1) of the first adhesive layer placed in an environment of 95°C and 0% RH was measured using a moisture adsorption and desorption measuring device (IGA-Sorp, manufactured by Hiden) until the weight change disappeared and the moisture was completely removed, and then the sample was placed in an environment of 80°C and 85% RH to observe the weight change. When the weight change of the sample disappeared (saturated state), its weight (W2) was measured. The saturated moisture content (saturated moisture content (A)) was measured by the following formula, and the saturated moisture content (B) at 25°C and 50% RH was measured according to the same steps, and their difference ((A)-(B)) was calculated. The results are shown in Table 1.

[0111]

[0112] [Evaluation of single-body transmittance in high-temperature environment (1)]

[0113] The polarizing film with an adhesive layer obtained above was cut into a size of 20×15 cm (with an in-plane size of 300 cm) so that the absorption axis of the polarizing film was the long side. 2), a glass plate (simulated image display unit) is bonded to the surface of the second transparent protective film of the polarizing film by means of an acrylic adhesive layer with a thickness of 20 μm as the second adhesive layer, and further, the first adhesive layer with the isolation film peeled off is bonded to another glass plate (front surface transparent component) to prepare a laminate (simulated image display device). The obtained laminate was placed in a hot air oven at a temperature of 95°C for 500 hours, and the monomer transmittance (ΔTs) before and after input (heating) was measured. The monomer transmittance was measured using a spectrophotometer (manufactured by Murakami Color Technology Research Institute Co., Ltd., product name "DOT-3") and evaluated according to the following criteria. The monomer transmittance is the Y value corrected for visibility using the 2-degree field of view (C light source) of JlS Z8701-1982. It should be noted that the measurement wavelength is 380 to 700 nm (every 10 nm). The results are shown in Table 1.

[0114] ΔTs(%)=Ts 500 -Ts0

[0115] Here, Ts0 is the transmittance of the laminated body before heating, and Ts 500 It is the single body transmittance of the laminated body after heating for 500 hours.

[0116] ◎: ΔTs (%) is 0% or more and within 5%.

[0117] ○: ΔTs (%) is greater than or equal to -1% and less than 0%.

[0118] Δ: ΔTs (%) is not less than -2% and less than -1%.

[0119] ×: ΔTs (%) is less than -2% or greater than 5%.

[0120] [Evaluation of single-body transmittance in high-temperature environment (2)]

[0121] In the above-mentioned [Evaluation of monomer transmittance in a high temperature environment (1)], the same operation as in the above-mentioned [Evaluation of monomer transmittance in a high temperature environment (1)] was performed, except that the sample was allowed to stand in a hot air oven at a temperature of 95°C for 1000 hours instead of standing in a hot air oven at a temperature of 95°C for 500 hours, and the monomer transmittance was evaluated according to the following criteria.

[0122] ΔTs(%)=Ts 1000 -Ts0

[0123] Here, Ts0 is the transmittance of the laminated body before heating, and Ts 1000 It is the single body transmittance of the laminated body after heating for 1000 hours.

[0124] ◎: ΔTs (%) is 0% or more and within 5%.

[0125] ○: ΔTs (%) is greater than or equal to -1% and less than 0%.

[0126] Δ: ΔTs (%) is not less than -2% and less than -1%.

[0127] ×: ΔTs (%) is less than -2% or greater than 5%.

[0128] [Evaluation of bubbles caused by foreign matter]

[0129] In the above-mentioned "Preparation of a polarizing film with an adhesive layer", a simulated foreign matter (glass) with an average particle size of 150 μm is mixed into the first transparent protective film of the obtained polarizing film and the first adhesive layer is attached to prepare a polarizing film with an adhesive layer. The obtained polarizing film with an adhesive layer is cut into a size of 20×15 cm (with an in-plane size of 300 cm) with the absorption axis of the polarizing film as the long side. 2 ), a glass plate (simulated image display unit) was bonded to the surface of the second transparent protective film of the polarizing film by means of an acrylic adhesive layer with a thickness of 20 μm as the second adhesive layer, and further, it was bonded to another glass plate (front surface transparent member) by means of the first adhesive layer from which the isolation film was peeled off, to prepare a laminate (simulated image display device). After the obtained laminate was left to stand in a hot air oven at a temperature of 95°C for 500 hours, the generation of bubbles due to foreign matter was evaluated according to the following criteria. The results are shown in Table 1.

[0130] ○: No bubbles were generated.

[0131] △: Bubbles are smaller than 100 μm.

[0132] ×: The bubbles grew to 100 μm or more.

[0133] [Determination of haze value]

[0134] The release films on both sides of the first adhesive layer prepared above with a release film on both sides were peeled off and attached to a glass slide (trade name: white polish No. 1, thickness: 0.8-1.0 mm, total light transmittance: 92%, haze: 0.2%, manufactured by Matsunami Glass Industries, Ltd.) to prepare a test piece with a layer structure of glass slide / adhesive layer / glass slide. The test piece was placed in an environment of 85°C and 85% RH for 1000 hours, and the haze value in the visible light region at the initial (X) and after placement (Y) was measured using a haze meter (device name: HM-150, manufactured by Murakami Color Research Institute, Ltd.). The results are shown in Table 1. It should be noted that the haze value of the first adhesive layer of the present invention before being placed in an environment of 85°C and 85% RH for 1000 hours (initial) is preferably less than 1.5, more preferably less than 1.0, and the haze value after being placed in an environment of 85°C and 85% RH for 1000 hours is preferably less than 3.0, more preferably less than 2.0, and the difference in haze value before and after being placed in an environment of 85°C and 85% RH for 1000 hours is preferably less than 1.5, more preferably less than 1.0.

[0135] <Examples 2 to 9 and Comparative Examples 1 to 4>

[0136] In Examples 2 to 9 and Comparative Examples 1 to 4, the same operation as in Example 1 was performed except that the type (thickness) of the polarizing film, the in-plane size of the polarizing film, and the type and thickness of the first adhesive layer were changed to the values ​​shown in Table 1, and the above evaluation was performed. The results are shown in Table 1. In-plane size of polarizing film 150 cm 2 15cm×10cm, internal dimension 600cm 2 30cm×20cm, inner dimension 900cm 2 The polarizing film B was 50 cm × 18 cm.

[0137] <Preparation of polarizing film>

[0138] <Polarizing Film B>

[0139] In the preparation of the polarizing film, a polyvinyl alcohol film having a thickness of 75 μm was stretched to 2.2 times in the conveying direction while being immersed in a swelling bath (water bath) at 35° C. for 30 seconds between rollers having different peripheral speed ratios (swelling process), and the iodine concentration of the dyeing bath was adjusted so that the iodine concentration of the polarizing film finally obtained was 2.5% by weight. The same operation as in Example 1 was performed to prepare the polarizing film and the polarizing film. The thickness of the obtained polarizing film was 28 μm. In addition, the monomer transmittance of the obtained polarizing film was 41.7%.

[0140] [Table 1]

[0141]

[0142] The polarizing films with adhesive layers of Examples 1 to 9 have a film thickness of 20 μm or less, the first adhesive layer is used for bonding to the front surface transparent member arranged on the recognition side of the image display device, and the difference ((A)-(B)) between the saturated moisture content (A) at 80°C and 85% RH and the saturated moisture content (B) at 25°C and 50% RH is 1.0 wt% or more, or the ratio ((A) / (B)) between the saturated moisture content (A) at 80°C and 85% RH and the saturated moisture content (B) at 25°C and 50% RH is 2.5 or less, so the results in the evaluation (1) of the single transmittance in the above-mentioned high temperature environment are ◎ or 0, and thus good results are shown. In particular, the polarizing films with adhesive layers of Examples 1 to 3 and 5 to 8 have a result of ◎ or 0 in the evaluation (2) of the single transmittance in the above-mentioned high temperature environment, and thus good results are shown.

[0143] On the other hand, the difference in the saturated moisture content ((A)-(B)) of the polarizing films with adhesive layers of Comparative Examples 1-2 was 0.8 wt %, and thus the result in the evaluation (1) of the single transmittance under the high temperature environment was △ or ×, showing a poor result. In addition, the film thickness of the polarizing film of the polarizing films with adhesive layers of Comparative Examples 3-4 was 28 μm, and thus the result in the evaluation (1) of the single transmittance under the high temperature environment was △ or ×, showing a poor result.

[0144] Description of Reference Numerals

[0145] 10: Polarizing film

[0146] 11: Polarizing film

[0147] 12: The first transparent protective film

[0148] 13: Second transparent protective film

[0149] 20: First adhesive layer

[0150] 30: Second adhesive layer

[0151] 45, 46: Isolation film

[0152] 70: Front surface transparent component

[0153] 71: Front surface transparent plate

[0154] 72: Printing steps

[0155] 90: Image display unit

[0156] 100: Polarizing film with adhesive layer

[0157] 110: Image display device

Claims

1. A polarizing film with an adhesive layer, characterized in that: The method comprises a polarizing film having a polarizing film and a first transparent protective film, and comprises a first adhesive layer disposed on the first transparent protective film side of the polarizing film. The polarizing film has a thickness of 20 μm or less. The first adhesive layer is used to adhere to the front surface transparent component arranged on the identification side of the image display device, and the difference AB between the saturated moisture content A at 80°C and 85% RH and the saturated moisture content B at 25°C and 50% RH is greater than 1.0 weight %, the ratio A / B of the saturated moisture content A at 80°C and 85% RH to the saturated moisture content B at 25°C and 50% RH is less than 2.5, and the thickness of the first adhesive layer is greater than 150 μm and less than 600 μm.

2. The polarizing film with an adhesive layer according to claim 1, wherein The moisture permeability of the first transparent protective film is 100 g / m 2 ·More than 24h.

3. The polarizing film with an adhesive layer according to claim 1 or 2, wherein The polarizing film has a second transparent protective film, The second transparent protective film is disposed on the side of the polarizing film opposite to the side having the first transparent protective film.

4. The polarizing film with an adhesive layer according to claim 3, wherein The polarizing film has a second adhesive layer, The second adhesive layer is disposed on the side of the polarizing film having the second transparent protective film.

5. The polarizing film with an adhesive layer according to claim 4, wherein The second adhesive layer has a thickness of 3 μm or more and 35 μm or less.

6. The polarizing film with an adhesive layer according to claim 1 or 2, wherein The in-plane size of the polarizing film is 300 cm 2 above.

7. An image display device comprising an image display unit and the front surface transparent member, The polarizing film with an adhesive layer according to any one of claims 1 to 6 is bonded to the front transparent member.

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