KR20240026520A - Polarizers and laminates - Google Patents

Abstract

The present invention provides a polarizing plate capable of sufficiently curing the ultraviolet addition-curing silicone adhesive composition even when a polarizing plate having a hard coat layer on the surface and a transparent member are bonded and laminated using an ultraviolet addition-curing silicone adhesive composition. The purpose is to The present invention provides a polarizing plate comprising a polarizer and a hard coat layer, wherein the hard coat layer constitutes at least one outermost surface of the polarizing plate, and the hard coat layer has an absorbance of 4.5 or less at a wavelength of 300 nm. do.

Description

Polarizers and laminates

The present invention relates to a polarizing plate, and further relates to a laminate provided with a polarizing plate.

Image display devices such as liquid crystal displays and organic EL displays are widely used for mobile applications such as personal computers and mobile phones, and in-vehicle applications such as car navigation systems. Generally, in image display devices used for such purposes, a transparent member such as a glass plate or a transparent resin plate is disposed on the surface to protect the display panel.

Additionally, a polarizing plate is generally used in a liquid crystal display panel or an organic EL display panel in many cases, and in this case, the transparent member and the polarizing plate are laminated through a pressure-sensitive adhesive layer or adhesive layer.

In order to improve the visibility and mechanical strength of an image display device, an ultraviolet curable acrylic resin composition is sometimes used as an adhesive for laminating a transparent member and a polarizing plate. However, ultraviolet curing acrylic resin compositions may be inhibited from curing by oxygen in the air. Therefore, an ultraviolet addition curing type silicone adhesive composition that cures the resin composition using a hydrosilylation reaction using an ultraviolet-activated platinum catalyst has been proposed (Patent Document 1).

Patent Document 1: Japanese Patent Publication No. 2020-055945

Since the ultraviolet addition curing type silicone adhesive composition has the property of gradually curing after irradiation with ultraviolet rays, the order of the adhesive composition application process, ultraviolet ray irradiation and composition curing process, and bonding process between members can be arbitrarily set. It has merit and is widely used.

However, when manufacturing an image display panel by laminating a polarizing plate with a hard coat layer on the surface and a transparent member, curing of the ultraviolet addition curing type silicone adhesive composition sometimes becomes insufficient.

The present invention provides a polarizing plate that can sufficiently cure the ultraviolet addition-curing silicone adhesive composition within a certain period of time even when a polarizing plate having a hard coat layer on the surface and a transparent member are bonded and laminated using an ultraviolet addition-curing silicone adhesive composition. The purpose is to provide

The present invention provides a polarizing plate and a laminate exemplified below.

[1] A polarizing plate including a polarizer and a hard coat layer, wherein the hard coat layer constitutes at least one outermost surface of the polarizing plate, and the hard coat layer has an absorbance of 4.5 or less at a wavelength of 300 nm.

[2] The hard coat layer is made of a cured layer of a photocurable resin composition,

The polarizing plate according to [1], wherein the photocurable resin composition contains a radical polymerization initiator as a photopolymerization initiator.

[3] The polarizing plate according to [1] or [2], wherein the cured layer of the photocurable resin composition contains a cured product of (meth)acrylic resin.

[4] The polarizing plate according to [2], wherein the radical polymerization initiator is an α-hydroxyacetophenone-based photopolymerization initiator or an α-aminoacetophenone-based photopolymerization initiator.

[5] The polarizing plate according to any one of [1] to [4], wherein the hard coat layer has a thickness of 0.5 μm or more and 10 μm or less.

[6] The polarizing plate according to any one of [1] to [5],

Provided with a transparent member,

A laminate in which the hard coat layer and the transparent member are laminated through an ultraviolet addition-curing silicone adhesive layer.

[7] The laminate according to [6], wherein the ultraviolet addition-curable silicone adhesive layer has a thickness of 10 μm or more and 1000 μm or less.

[8] The laminate according to [6] or [7], wherein the ultraviolet addition-curing silicone adhesive layer is a cured layer of an ultraviolet addition-curing silicone adhesive composition.

[9] The laminate according to any one of [6] to [8], wherein the transparent member is a glass plate, a transparent resin plate, or a touch panel.

According to the present invention, even when a polarizing plate having a hard coat layer on the surface and a transparent member are bonded and laminated using an ultraviolet addition-curing silicone adhesive composition, the polarizing plate is capable of sufficiently curing the ultraviolet addition-curing silicone adhesive composition within a certain period of time. can be provided.

1 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate.
Figure 2 is a schematic cross-sectional view showing another example of the layer structure of the laminate.
Figure 3 is a conceptual diagram explaining the curing time of an ultraviolet addition-curable silicone adhesive composition.
Figure 4 is a schematic cross-sectional view illustrating a method of measuring the curing time of an ultraviolet addition-curable silicone adhesive composition.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all drawings below, the scale of each component is appropriately adjusted to make it easier to understand, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

<Polarizer>

The polarizing plate of this embodiment is provided with a polarizer and a hard coat layer, the hard coat layer constitutes at least one outermost surface of the polarizing plate, and the absorbance of the hard coat layer at a wavelength of 300 nm is 4.5 or less. The polarizing plate of this embodiment will be described below with reference to the drawings. The polarizing plate 10 shown in FIG. 1 includes a polarizer 11 and a hard coat layer 12. The polarizing plate 10 may further include layers other than the layers described above. Examples of other layers include thermoplastic resin films, bonding layers, optical function layers, and protective films. The polarizing plate 10 shown in FIG. 1 further includes a thermoplastic resin film 13 between the polarizer 11 and the hard coat layer 12. The polarizing plate may be a linear polarizing plate, or may be a circular polarizing plate in which a retardation layer, which will be described later, is laminated on a linear polarizing plate.

[Polarizer]

The polarizer 11 is formed by adsorbing and orienting a dichroic dye to a layer containing polyvinyl alcohol (hereinafter also referred to as “PVA”)-based resin (in this specification, also referred to as “PVA-based resin layer”). A polarizer can be used. Such a polarizer is formed by using a PVA-based resin film, dyeing the PVA-based resin film with a dichroic dye, and uniaxially stretching it, or a laminated film obtained by applying a coating liquid containing PVA-based resin onto a base film. Examples include those formed by dyeing the PVA-based resin layer, which is the application layer of this laminated film, with a dichroic dye and uniaxially stretching the laminated film.

The polarizer 11 is formed of PVA-based resin obtained by saponifying polyvinyl acetate-based resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable therewith. Other copolymerizable monomers include, for example, unsaturated carboxylic acids, olefins such as ethylene, vinyl ethers, and unsaturated sulfonic acids.

The saponification degree of the PVA-based resin is preferably 85 mol% or more, more preferably 90 mol% or more, and even more preferably 99 mol% to 100 mol%. The degree of polymerization of PVA-based resin is 1000 to 10000, preferably 1500 to 5000. This PVA-based resin may be modified, and may be, for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc. modified with aldehydes.

The thickness of the polarizer 11 is preferably 5 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and even more preferably 8 μm or more and 30 μm or less. When the thickness of the polarizer 11 is 50 μm or less, the influence of polyenization of the PVA-based resin in a high temperature environment on the deterioration of optical properties can be reduced, and by the thickness of the polarizer 11 is 5 μm or more. It becomes easier to achieve desired optical properties.

The water content of the polarizer 11 may be greater than or equal to the equilibrium water content of 20% relative humidity at a temperature of 20°C, and may be less than or equal to the equilibrium water content of 48% of relative humidity at a temperature of 20°C. The moisture content of the polarizer 11 is preferably equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 30%, and is equal to or lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 45%. The water content of the polarizer 11 is more preferably less than or equal to the equilibrium water content at a temperature of 20°C and a relative humidity of 42%, further preferably is less than or equal to the equilibrium water content of a temperature of 20°C and a relative humidity of 40%, and most preferably, the temperature is It is below the equilibrium moisture content of 38% relative humidity at 20℃. If the moisture content of the polarizer 11 is lower than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 20%, the handling properties of the polarizer 11 deteriorate and the polarizer 11 becomes fragile. When the water content of the polarizer 11 is below the equilibrium water content at a temperature of 20°C and a relative humidity of 48%, a laminate with excellent high-temperature durability can be provided. The water content of the polarizer 11 is the water content of the polarizer in the polarizing plate.

The manufacturing method of the polarizer 11 is not particularly limited, but is manufactured by sending out a polyvinyl alcohol-based resin film previously wound into a roll and performing stretching, dyeing, crosslinking, etc. (hereinafter referred to as “Manufacturing Method 1”). or a method comprising the step of applying a coating liquid containing a polyvinyl alcohol-based resin on a base film to form a polyvinyl alcohol-based resin layer as an application layer and stretching the obtained laminate (hereinafter referred to as “manufacturing method 2”) ) is typical.

Manufacturing method 1 is a process of uniaxially stretching a polyvinyl alcohol-based resin film, dyeing the polyvinyl alcohol-based resin film with a dichroic dye such as iodine, and adsorbing the dichroic dye, and forming a polyvinyl alcohol-based resin film with the dichroic dye adsorbed. It can be manufactured through a process of treating a vinyl alcohol-based resin film with an aqueous boric acid solution, and a process of washing with water after treatment with an aqueous boric acid solution.

The swelling process is a treatment process in which the polyvinyl alcohol-based resin film is immersed in a swelling bath, and dirt and blocking agents, etc. on the surface of the polyvinyl alcohol-based resin film can be removed, and the polyvinyl alcohol-based resin film can be Swelling can suppress dyeing stains. The swelling bath usually uses a medium containing water as a main ingredient, such as water, distilled water, or pure water. A surfactant, alcohol, etc. may be appropriately added to the swelling bath according to a conventional method.

The temperature of the swelling bath is preferably 10 to 60°C, more preferably 15 to 45°C, and even more preferably 18 to 30°C. In addition, the immersion time in the swelling bath cannot be uniformly determined because the degree of swelling of the polyvinyl alcohol-based resin film is affected by the temperature of the swelling bath, but is preferably 5 to 300 seconds, and 10 to 200 seconds. It is more preferable, and it is further more preferable that it is 20 to 100 seconds. The swelling process may be performed only once, or may be performed multiple times as needed.

The dyeing process is a treatment process in which the polyvinyl alcohol-based resin film is immersed in a dyeing bath (iodine solution), and dichroic substances such as iodine or dichroic dye can be adsorbed and oriented on the polyvinyl alcohol-based resin film. . The iodine solution is usually preferably an iodine aqueous solution and contains iodide as a dissolution aid. Additionally, examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Among these, potassium iodide is suitable from the viewpoint of controlling the potassium content in the polarizer.

The concentration of iodine in the dyeing bath is preferably 0.01 to 1% by mass, and more preferably 0.02 to 0.5% by mass. The concentration of iodide in the dyeing bath is preferably 0.01 to 10 mass%, more preferably 0.05 to 5 mass%, and even more preferably 0.1 to 3 mass%.

The temperature of the dyeing bath is preferably 10 to 50°C, more preferably 15 to 45°C, and even more preferably 18 to 30°C. In addition, the immersion time in the dyeing bath cannot be uniformly determined because the degree of dyeing of the polyvinyl alcohol-based resin film is affected by the temperature of the dyeing bath, but is preferably 10 to 300 seconds, and 20 to 240 seconds. It is more desirable. The dyeing process may be performed only once, or may be performed multiple times as needed.

The cross-linking process is a treatment process in which the polyvinyl alcohol-based resin film dyed in the dyeing process is immersed in a treatment bath (cross-linking bath) containing a boron compound. The polyvinyl alcohol-based resin film is cross-linked by the boron compound, and iodine is added to the polyvinyl alcohol-based resin film. Molecules or dye molecules may be adsorbed to the cross-linked structure. Examples of boron compounds include boric acid, borate, and borax. The crosslinking bath is generally an aqueous solution, but may be, for example, a mixed solution of water and an organic solvent miscible with water. Additionally, the crosslinking bath preferably contains potassium iodide from the viewpoint of controlling the potassium content in the polarizer.

The concentration of the boron compound in the crosslinking bath is preferably 1 to 15 mass%, more preferably 1.5 to 10 mass%, and more preferably 2 to 5 mass%. In addition, when potassium iodide is used in the cross-linking bath, the concentration of potassium iodide in the cross-linking bath is preferably 1 to 15% by mass, more preferably 1.5 to 10% by mass, and 2 to 5% by mass. It is more desirable.

The temperature of the crosslinking bath is preferably 20 to 70°C, and more preferably 30 to 60°C. In addition, the immersion time in the crosslinking bath cannot be uniformly determined because the degree of crosslinking of the polyvinyl alcohol-based resin film is affected by the temperature of the crosslinking bath, but is preferably 5 to 300 seconds, and 10 to 200 seconds. It is more desirable. The crosslinking process may be performed only once, or may be performed multiple times as needed.

The stretching process is a treatment process in which the polyvinyl alcohol-based resin film is stretched at a predetermined magnification in at least one direction. Generally, a polyvinyl alcohol-based resin film is uniaxially stretched in the conveyance direction (longitudinal direction). The stretching method is not particularly limited, and either a wet stretching method or a dry stretching method can be employed. The stretching process may be performed only once, or may be performed multiple times as needed. The stretching process may be performed at any stage in the manufacture of the polarizer.

The treatment bath (stretching bath) in the wet stretching method can usually use a solvent such as water or a mixed solution of water and an organic solvent miscible with water. The stretching bath preferably contains potassium iodide from the viewpoint of controlling the potassium content in the polarizer. When potassium iodide is used in a stretching bath, the concentration of potassium iodide in the stretching bath is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and more preferably 3 to 6% by mass. desirable. In addition, the treatment bath (stretching bath) may contain a boron compound from the viewpoint of suppressing film breakage during stretching. In this case, the concentration of the boron compound in the stretching bath is preferably 1 to 15% by mass. It is more preferable that it is 1.5 to 10 mass %, and it is more preferable that it is 2 to 5 mass %.

The temperature of the stretching bath is preferably 25 to 80°C, more preferably 40 to 75°C, and even more preferably 50 to 70°C. In addition, the immersion time in the stretching bath cannot be uniformly determined because the stretching degree of the polyvinyl alcohol-based resin film is affected by the temperature of the stretching bath, but is preferably 10 to 800 seconds, and 30 to 500 seconds. It is more desirable. In addition, the stretching treatment in the wet stretching method may be performed together with any one or more of the swelling process, dyeing process, crosslinking process, and washing process.

Examples of dry stretching methods include roll-to-roll stretching methods, heated roll stretching methods, and compression stretching methods. Additionally, the dry stretching method may be performed together with the drying process.

The total stretch ratio (cumulative stretch ratio) applied to the polyvinyl alcohol-based resin film can be set appropriately depending on the purpose, but is preferably 2 to 7 times, more preferably 3 to 6.8 times, and 3.5 to 6.5 times. It is more desirable.

The washing process is a treatment process in which the polyvinyl alcohol-based resin film is immersed in a washing bath, and foreign substances remaining on the surface of the polyvinyl alcohol-based resin film, etc. can be removed. As a washing bath, a medium containing water as a main component, such as water, distilled water, or pure water, is usually used. Additionally, from the viewpoint of controlling the potassium content in the polarizer, it is preferable to use potassium iodide in the washing bath. In this case, the concentration of potassium iodide in the washing bath is preferably 1 to 10% by mass, and 1.5 to 1.5% by mass. It is more preferable that it is 4 mass%, and it is still more preferable that it is 1.8-3.8 mass%.

The temperature of the washing bath is preferably 5 to 50°C, more preferably 10 to 40°C, and even more preferably 15 to 30°C. In addition, the immersion time in the washing bath cannot be uniformly determined because the degree of cleaning of the polyvinyl alcohol-based resin film is affected by the temperature of the washing bath, but is preferably 1 to 100 seconds, and 2 to 50 seconds. More preferably, it is further preferably 3 to 20 seconds. The cleaning process may be performed only once, or may be performed multiple times as needed.

The drying process is a process of obtaining a polarizer by drying the polyvinyl alcohol-based resin film washed in the washing process. Drying is performed by any appropriate method, and examples include natural drying, blow drying, and heat drying.

Manufacturing method 2 is a process of applying a coating liquid containing the polyvinyl alcohol-based resin onto a base film, a process of uniaxially stretching the obtained laminated film, and adding a dichroic dye to the polyvinyl alcohol-based resin layer of the uniaxially stretched laminated film. It can be manufactured through the following steps: a step of adsorbing the dichroic dye to form a polarizer by dyeing, a step of treating the film to which the dichroic dye has been adsorbed with an aqueous boric acid solution, and a step of washing with water after treatment with the aqueous boric acid solution. The base film used to form a polarizer may be used as a protective layer of the polarizer. If necessary, the base film may be peeled and removed from the polarizer.

[Hard coat layer]

The hard coat layer 12 may have a function of improving the scratch resistance of the polarizing plate 10. The hard coat layer 12 constitutes at least one outermost surface of the polarizing plate 10. When the polarizing plate has two or more hard coat layers, the hard coat layers may be arranged so as to constitute the outermost surfaces on both sides of the polarizing plate 10.

The hard coat layer 12 has an absorbance of 4.5 or less at a wavelength of 300 nm. As a result of research by the present inventor, if the absorbance of the hard coat layer 12 at a wavelength of 300 nm is 4.5 or less, even when the polarizing plate and the transparent member are bonded and laminated with an ultraviolet addition curing type silicone adhesive composition, ultraviolet rays are added. It has been discovered that a curable silicone adhesive composition can be sufficiently cured. As described later, when the type and content of the photopolymerization initiator in the hard coat layer forming composition is adjusted so that the absorbance of the hard coat layer at a wavelength of 300 nm is 4.5 or less, the photopolymerization initiator in the hard coat layer is exposed to ultraviolet rays. It is presumed that this is because it becomes difficult to react with the vinyl group contained in the curable silicone adhesive composition, and curing inhibition is easily suppressed.

The absorbance of the hard coat layer 12 at a wavelength of 300 nm is preferably 3.5 or less, more preferably 3.0 or less, from the viewpoint of making it easy to shorten the curing time of the ultraviolet curing silicone adhesive, and even more preferably It is 2.5 or less, particularly preferably 2.0 or less, more particularly preferably 1.5 or less, and even more particularly preferably 1.0 or less. The absorbance of the hard coat layer 12 at a wavelength of 300 nm is usually greater than 0, and may be, for example, 0.01 or more or 0.1 or more.

Methods for adjusting the absorbance of the hard coat layer 12 to 4.5 or less include, for example, a method of selecting the type of photopolymerization initiator used in the composition for forming a hard coat layer, a method of adjusting the content of the photopolymerization initiator in the composition for forming a hard coat layer, Methods for controlling the thickness of the hard coat layer, and combinations thereof, etc. are included.

The hard coat layer 12 is preferably composed of a cured layer of a photocurable resin composition (hereinafter also referred to as a composition for forming a hard coat layer). Examples of the photocurable resin include active energy ray curable resin. The composition for forming a hard coat layer contains a photocurable resin. The composition for forming the hard coat layer may be, for example, a radically curable composition. The composition for forming a hard coat layer may contain, for example, a polymerization initiator, additives, solvent, etc. in addition to the photocurable resin. Additives include, for example, plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments and dyes, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, surfactants, etc. .

Photocurable resins include polyester resins, (meth)acrylic resins, urethane resins, (meth)acrylic urethane resins, amide resins, silicone resins, silicate resins, epoxy resins, melamine resins, and oxetane resins. Various resins can be mentioned. These curable resins can be used alone or in combination of two or more, appropriately selected. In this specification, “(meth)acrylic” means acrylic and/or methacrylic, and also includes “(meth)” when referring to “(meth)acrylate,” “(meth)acryloyl,” etc. It has the same purpose.

Among these, (meth)acrylic resin, (meth)acrylic urethane resin, and epoxy resin are preferable because they have high hardness, can be cured with ultraviolet rays, and are excellent in productivity, and among them, (meth)acrylic resin is preferable. Ultraviolet curable resins include ultraviolet curable monomers, oligomers, polymers, etc. Preferably used ultraviolet curable resins include, for example, those having an ultraviolet polymerizable functional group, and those containing as a component an acrylic monomer or oligomer having two or more, especially three to six, functional groups. Such compounds include, for example, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, and triacrylate. Ethylene glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, EO modified pentaerythritol tetra(meth)acrylate, PO modified pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth) Acrylate, trimethylolpropane tri(meth)acrylate, EO modified trimethylolpropane tri(meth)acrylate, PO modified trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, ditrimethylol Propane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tricyclodecane dimethanol di(meth) Acrylates, etc. can be mentioned.

Among them, pentaerythritol tetra(meth)acrylate, EO modified pentaerythritol tetra(meth)acrylate, PO modified pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri. (meth)acrylate, EO modified trimethylolpropane tri(meth)acrylate, PO modified trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, tricyclodecane dimethanol di(meth) Acrylates are preferred.

These can be contained in combination of two or more types. Additionally, commercial products containing two or more types can also be used.

(Meth)acrylic resins can be used commercially, such as NK ester A-DCP, DCP, A-TMPT, TMPT, ATM-35E, A-TMMT manufactured by Shinnakamura Chemical Industry Co., Ltd., Osaka Yuki Chemical Industry Co., Ltd. Viscot (registered trademark) #195, Viscot (registered trademark) #300, Viscot (registered trademark) #360 manufactured by Daicel and Allnex Co., Ltd., acrylate monomer IRR 214-K, PETIA, manufactured by Daicel and Allnex Co., Ltd. PETRA, TMPTA, TMPEOTA, EBECRYL 135, OTA 480, EBERCRYL 40, Beam Set 710 and Beam Set 730 manufactured by Arakawa Kagaku Kogyo Co., Ltd.

The (meth)acrylic resin is preferably 10% by mass or more and 99% by mass or less, and more preferably 50% by mass or more and 99% by mass or less, in the solid content of the composition for forming a hard coat layer.

In order to provide the polarizing plate with anti-glare properties and anti-glare properties, it is preferable that the hard coat layer has anti-glare properties. Examples of the anti-glare hard coat layer include those in which fine particles are dispersed in a matrix resin containing the photocurable resin described above. The fine particles to be dispersed in the matrix resin include various metal oxide fine particles such as silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide, glass fine particles, polymethyl methacrylate, polystyrene, and polyurethane. , crosslinked or uncrosslinked organic fine particles including various transparent polymers such as acrylic-styrene copolymer, benzoguanamine, melamine, polycarbonate, silicone fine particles, etc. can be used without particular limitation. These fine particles can be used by appropriately selecting one type or two or more types. Among them, fine particles with a higher refractive index than the matrix resin are preferable, and, for example, organic fine particles with a refractive index of 1.5 or higher, such as styrene beads (refractive index 1.59), are preferable. The average particle diameter of the fine particles is preferably 1 to 10 μm, more preferably 2 to 5 μm. The proportion of fine particles is not particularly limited, but is preferably 6 to 20 parts by mass per 100 parts by mass of the matrix resin.

When the composition for forming a hard coat layer is a radically curable composition, a radical polymerization initiator can be used as the photopolymerization initiator. Examples of the radical polymerization initiator include α-hydroxyacetophenone-based photopolymerization initiators, α-aminoacetophenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, and intramolecular hydrogen abstraction type photopolymerization initiators. Among them, an α-hydroxyacetophenone-based photopolymerization initiator and an α-aminoacetophenone-based photopolymerization initiator are preferable from the viewpoint of making it easier to shorten the curing time of the ultraviolet curing silicone adhesive. The photopolymerization initiator can be a commercially available product.

Examples of commercially available α-hydroxyacetophenone photopolymerization initiators include Omnirad 2959, Omnirad 184, Omnirad 127D, and Omnirad 1173 (IGM Resins). Examples of commercially available α-aminoacetophenone photopolymerization initiators include Omnirad 907, Omnirad 369E (IGM Resins), and the like.

The content of the photopolymerization initiator in the composition for forming a hard coat layer may be, for example, 0.1 part by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the photocurable resin, and is preferable from the viewpoint of making it easier to shorten the curing time of the ultraviolet curing silicone adhesive. Preferably it is 1 part by mass or more and 10 parts by mass or less, more preferably 2 parts by mass or more and 8 parts by mass or less, and even more preferably 3 parts by mass or more and 6 parts by mass or less.

The cured layer of the composition for forming a hard coat can be formed by applying the composition for forming a hard coat layer on a polarizer or a thermoplastic resin film and curing it by light irradiation. The thermoplastic resin film provided with the hard coat layer 12 can be bonded to the polarizer 11 through a bonding layer.

The thickness of the hard coat layer 12 may be, for example, 10 μm or less, and is preferably 8 μm or less. The thickness of the hard coat layer is usually 0.5 μm or more.

[Thermoplastic resin film]

The thermoplastic resin film 13 may function as a protective film that protects the surface of the polarizer 11 and as a base film that supports the hard coat layer. The thermoplastic resin film 13 can be laminated on the polarizer only through the bonding layer.

The thermoplastic resin film 13 is not particularly limited, but may include a light-transmitting (preferably optically transparent) thermoplastic resin, such as chain polyolefin resin (polypropylene resin, etc.), cyclic polyolefin resin (norbornene resin, etc.) ), polyolefin-based resins such as; Cellulose-based resins such as triacetylcellulose and diacetylcellulose; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resins such as methyl methacrylate resins; polystyrene-based resin; polyvinyl chloride-based resin; Acrylonitrile, butadiene, and styrene-based resin; Acrylonitrile/styrene resin; polyvinyl acetate-based resin; polyvinylidene chloride-based resin; polyamide-based resin; polyacetal resin; Modified polyphenylene ether-based resin; polysulfone-based resin; polyethersulfone-based resin; polyarylate-based resin; polyamideimide-based resin; polyimide resin; It may be a film made of maleimide resin or the like. Among these, it is preferable to use a film containing at least one selected from the group consisting of cellulose resin, cyclic polyolefin resin, (meth)acrylic resin, polystyrene resin, and maleimide resin.

These resins can be used individually or in combination of two or more types. In addition, these resins can also be used after performing any appropriate polymer modification. The polymer modification includes, for example, copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reaction between heterogeneous polymers. Modifications such as mixing containing .

The cellulose resin may be an organic acid ester or mixed organic acid ester of cellulose in which some or all of the hydrogen atoms in the hydroxyl group of cellulose are replaced with an acetyl group, a propionyl group, and/or a butyryl group. For example, those containing acetic acid ester of cellulose, propionic acid ester, butyric acid ester, mixed esters thereof, etc. Among them, triacetylcellulose, diacetylcellulose, cellulose acetate propionate, cellulose acetate butyrate, etc. are preferable.

These resins may be blended with appropriate additives as long as transparency is not impaired. As additives, for example, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, anti-fog agents, anti-blocking agents, retardation reducers, stabilizers, processing aids, plasticizers, impact-resistant aids, matting agents, antibacterial agents, molds. Preventative agents, etc. can be mentioned. Multiple types of these additives may be used together.

The thickness of the thermoplastic resin film 13 is usually 1 μm or more and 100 μm or less, but from the viewpoint of strength, handling, etc., it is preferably 5 μm or more and 60 μm or less, more preferably 10 μm or more and 55 μm or less, and 15 μm or more. It is more preferable that it is 50 μm or less.

The thermoplastic resin film 13 may have different optical functions at the same time, and may be formed in a laminated structure in which a plurality of layers are laminated. It is preferable that the film thickness of the protective film or thermoplastic resin film is thin from the viewpoint of optical properties, but if it is too thin, the strength will decrease and processability will be poor. An appropriate film thickness is 5 μm or more and 100 μm or less, preferably 10 μm or more and 80 μm or less, and more preferably 15 μm or more and 70 μm or less.

In the configuration having thermoplastic resin films on both sides of the polarizer 11, when bonding using a water-based adhesive such as PVA adhesive, at least one thermoplastic resin film 13 is a cellulose acylate-based film or (from the viewpoint of moisture permeability). Any of the meth)acrylic resin films is preferable, and among them, a cellulose acylate film is preferable.

In the case of a structure having thermoplastic resin films on both surfaces of the polarizer 11, the types of thermoplastic resin films may be the same or different. When the polarizer 11 has a thermoplastic resin film on both sides, the thermoplastic resin film with a hard coat layer can be disposed so that the hard coat layer constitutes the outermost surfaces of both sides of the polarizer 10. The thermoplastic resin film may be provided with a surface treatment layer (coating layer) such as an antistatic layer on its outer surface (the surface opposite to the polarizer 11). In addition, the thickness of the thermoplastic resin film includes the thickness of the surface treatment layer.

The thermoplastic resin film 13 may have a phase difference function for purposes such as viewing angle compensation. In that case, the film itself may have a phase difference function, it may have a separate phase difference layer, or it may be a combination of both. Additionally, the film with a retardation function may be configured to be bonded to the polarizer 11 by means of an adhesive layer or an adhesive layer via another thermoplastic resin film bonded to the polarizer 11.

[Bonding layer]

In the polarizing plate 10, a bonding layer is used to bond each layer. Examples of the bonding layer include an adhesive layer or an adhesive layer. The polarizing plate 10 can also be made into a polarizing plate with an adhesive layer by laminating an adhesive layer to bond it to an image display cell, which will be described later.

(Adhesive layer)

The adhesive layer can be used for bonding the thermoplastic resin film 13 to the polarizer 11, for example. The adhesive constituting the adhesive layer can be any suitable adhesive. The adhesive may be a water-based adhesive, a solvent-based adhesive, or a photocurable adhesive, but it is preferable that it is a water-based adhesive.

The thickness when applying the adhesive can be set to any appropriate value. For example, after curing or heating (drying), it is set so that an adhesive layer with a desired thickness is obtained. The thickness of the adhesive layer is preferably 0.01 μm or more and 7 μm or less, more preferably 0.01 μm or more and 5 μm or less, further preferably 0.01 μm or more and 2 μm or less, and most preferably 0.01 μm or more and 1 μm. It is as follows.

(Water-based adhesive)

As the water-based adhesive, any suitable water-based adhesive may be employed. Among them, a water-based adhesive containing PVA-based resin (PVA-based adhesive) is preferably used. The average degree of polymerization of the PVA-based resin contained in the water-based adhesive is preferably 100 to 5,500, more preferably 1,000 to 4,500 from the viewpoint of adhesiveness. From the viewpoint of adhesiveness, the average degree of saponification is preferably 85 mol% to 100 mol%, and more preferably 90 mol% to 100 mol%.

As the PVA-based resin contained in the water-based adhesive, one containing an acetoacetyl group is preferable, because it is excellent in adhesion between the PVA-based resin layer and the protective film and is excellent in durability. PVA-based resin containing an acetoacetyl group is obtained, for example, by reacting PVA-based resin and diketene by an arbitrary method. The acetoacetyl group modification degree of the acetoacetyl group-containing PVA-based resin is typically 0.1 mol% or more, and is preferably 0.1 mol% to 20 mol%.

The resin concentration of the water-based adhesive is preferably 0.1 mass% or more and 15 mass% or less, and more preferably 0.5 mass% or more and 10 mass% or less.

A water-based adhesive may also contain a crosslinking agent. As a crosslinking agent, a known crosslinking agent can be used. Examples include water-soluble epoxy compounds, dialdehyde, and isocyanate.

When the PVA-based resin is a PVA-based resin containing an acetoacetyl group, the crosslinking agent is preferably any one of glyoxal, glyoxylate, and methylolmelamine, and is preferably any one of glyoxal and glyoxylate. It is particularly preferable that it is oxalate.

Water-based adhesives may contain organic solvents. The organic solvent is preferably alcohol because it is miscible with water, and among alcohols, methanol or ethanol is more preferable.

The methanol concentration of the water-based adhesive is preferably 10 mass% or more and 70 mass% or less, more preferably 15 mass% or more and 60 mass% or less, and even more preferably 20 mass% or more and 60 mass% or less. When the concentration of methanol is 10% by mass or more, it becomes easier to suppress polyenization in a high temperature environment. Additionally, when the methanol content is 70% by mass or less, color deterioration can be suppressed.

(Light-curing adhesive)

A photocurable adhesive is an adhesive that is cured by irradiating ultraviolet rays or the like, and includes, for example, an adhesive containing a polymerizable compound and a photopolymerizable initiator, an adhesive containing a photoreactive resin, an adhesive containing a binder resin and a photoreactive crosslinking agent, etc. You can. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from these monomers. Examples of the photopolymerization initiator include compounds containing a substance that generates active species such as neutral radicals, anion radicals, and cation radicals when irradiated with ultraviolet rays or the like.

(Adhesive layer)

The adhesive layer can be used, for example, for bonding the retardation film described later. The adhesive layer can be composed of an adhesive composition containing as a main component a resin such as (meth)acrylic resin, rubber-based resin, urethane-based resin, ester-based resin, silicone-based resin, and polyvinyl ether-based resin. Among them, an adhesive composition containing a (meth)acrylic resin excellent in transparency, weather resistance, heat resistance, etc. as a base polymer is suitable. The adhesive composition may be of a photocuring type or a thermosetting type. The thickness of the adhesive layer is usually 3 μm or more and 30 μm or less, and is preferably 3 μm or more and 25 μm or less.

Examples of the (meth)acrylic resin (base polymer) used in the adhesive composition include (meth)acrylic acid such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. A polymer or copolymer containing one or two or more types of ester as a monomer is suitably used. It is preferable to copolymerize a polar monomer with the base polymer. Polar monomers include, for example, (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl. Monomers having a carboxyl group, hydroxyl group, amide group, amino group, epoxy group, etc., such as (meth)acrylate, can be mentioned.

The pressure-sensitive adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. Examples of the crosslinking agent include metal ions of divalence or higher, which form a metal carboxylic acid salt between carboxyl groups; A polyamine compound that forms an amide bond between carboxyl groups; A polyepoxy compound or polyol that forms an ester bond between carboxyl groups; As a polyisocyanate compound, one that forms an amide bond between carboxyl groups is exemplified. Among them, polyisocyanate compounds are preferable.

The thickness of the adhesive layer is preferably 1 μm or more and 200 μm or less, more preferably 2 μm or more and 100 μm or less, more preferably 2 μm or more and 80 μm or less, and especially preferably 3 μm or more and 50 μm or less.

[Optical functional layer]

The optical functional layer may be, for example, a phase contrast layer. Examples of the phase difference layer include a layer that provides a phase difference of λ/2, a layer that provides a phase difference of λ/4 (positive A plate), and a positive C plate. The optical function layer may contain an alignment layer and a base material, and may have two or more liquid crystal layers, an orientation layer, and a base material. When the polarizing plate has a polarizing element and a film that provides a phase difference of λ/4, the polarizing plate may be a circularly polarizing plate.

The thermoplastic resin film 13 may also serve as a retardation layer, but the retardation layer may be laminated separately from these films. In the latter case, the retardation layer can be laminated on the polarizing plate through a pressure-sensitive adhesive layer or adhesive layer.

Examples of the retardation layer include a birefringent film composed of a stretched film of a translucent thermoplastic resin, the above-described liquid crystal layer formed on a base film, and the like. The base film is usually a film made of a thermoplastic resin, and an example of the thermoplastic resin is a cellulose ester-based resin such as triacetylcellulose.

Examples of other optical functional layers include a light collecting plate, a brightness enhancing film, a reflective layer (reflective film), a transflective reflective layer (transflective reflective film), a light diffusion layer (light diffusion film), and an anti-reflective film.

[Protect Film]

The polarizing plate 10 can be made into a polarizing plate with a protection film by laminating a protection film to protect its surface (typically the surface of a polarizer, a hard coat layer, or a thermoplastic resin film). For example, after the polarizing plate 10 is bonded to an image display element or another optical member, the protective film is peeled and removed together with the adhesive layer it has.

The protective film is comprised, for example, of a base film and an adhesive layer laminated thereon. For the adhesive layer, the above-described technology is cited.

Resins constituting the base film include, for example, polyethylene-based resins such as polyethylene; Polypropylene-based resins such as polypropylene; Polyester resins such as polyethylene terephthalate and polyethylene naphthalate; It may be a thermoplastic resin of polycarbonate-based resin. Preferably, it is a polyester resin such as polyethylene terephthalate.

The thickness of the protective film is not particularly limited, but is preferably in the range of 20 µm or more and 200 µm or less. When the thickness of the base material is 20 μm or more, strength tends to be easily imparted to the polarizing plate 10.

[Method of manufacturing polarizer]

The method of manufacturing the polarizing plate 10 is, for example, forming the hard coat layer 12 on the thermoplastic resin film 13, and then forming the hard coat layer 12 on the side of the thermoplastic resin film 13 opposite to the hard coat layer 12 side. This may be a method of obtaining a polarizing plate by bonding the polarizer 11 through a bonding layer.

<Laminate>

The laminate of this embodiment includes the above-described polarizing plate 10 and a transparent member, and the hard coat layer 12 and the transparent member are laminated through an ultraviolet addition curing type silicone adhesive layer. Referring to FIG. 2, the laminate of this embodiment will be described. The laminate 20 shown in FIG. 2 includes a polarizing plate 10, an ultraviolet addition-curable silicone adhesive layer 21, and a transparent member 22.

[UV addition-curable silicone adhesive layer]

The ultraviolet addition-curable silicone adhesive layer 21 may have the function of adhering the polarizing plate 10 and the transparent member 22. The ultraviolet addition-curable silicone adhesive layer 21 may have light transparency and is preferably optically transparent.

The thickness of the ultraviolet addition-curable silicone adhesive layer 21 may be, for example, 10 μm or more and 1000 μm or less, preferably 15 μm or more and 800 μm or less, more preferably 20 μm or more and 700 μm or less, and even more preferably 25 μm. It is less than or equal to 600 ㎛.

The ultraviolet addition-curing type silicone adhesive layer 21 can be formed from an ultraviolet addition-curing type silicone adhesive composition. The ultraviolet addition-curable silicone adhesive composition does not harden immediately after irradiation of ultraviolet rays, but the curing reaction begins gradually after irradiation of ultraviolet rays, so joining or fixing the members between irradiation of ultraviolet rays and until curing is performed. It tends to get easier. The ultraviolet addition curing type silicone adhesive composition may have light transparency before curing, and from the viewpoint of curing properties, it preferably has colorless transparency before curing, and more preferably has colorless transparency before and after curing.

The curing time of the ultraviolet addition-curable silicone adhesive composition may be, for example, 1 minute or more and 24 hours or less under an air atmosphere at a temperature of 20°C or higher and 80°C or lower. In this specification, the curing time of the ultraviolet curable silicone adhesive refers to irradiating the ultraviolet curable silicone adhesive with ultraviolet rays to initiate a curing reaction, performing dynamic viscoelasticity measurement while curing, and measuring the storage shear modulus and This refers to the time it takes for the loss shear modulus to become the same. When explaining the curing time with reference to FIG. 3, when G' represents the storage modulus and G'' represents the loss modulus, from the start point (A) of the dynamic viscoelasticity measurement, G' and G'' become the same. The time between the starting point (gelation point (31)) (B) is the curing time. Additionally, the time from irradiation of ultraviolet rays to the start of dynamic viscoelasticity measurement is usually 5 minutes.

The ultraviolet addition-curable silicone adhesive composition may be, for example, a composition containing a silicone polymer having an alkenyl group, a silicone polymer having an H group, and a photoactivation catalyst. It can be cured through a hydrosilylation reaction.

The alkenyl group preferably has 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms. Specifically, vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, etc. are exemplified, and vinyl group is especially preferable.

The silicone polymer having an alkenyl group may have at least one of a monovalent saturated hydrocarbon group and an aryl group in addition to the alkenyl group.

The monovalent saturated hydrocarbon group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms. Specifically, it may be linear, branched, or cyclic, and may be methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, Straight-chain or branched alkyl groups such as n-hexyl group and n-heptyl group; Cycloalkyl groups such as cyclohexyl groups; Examples include unsubstituted or substituted monovalent saturated hydrocarbon groups such as halogenated alkyl groups such as chloromethyl group, 3-chloropropyl group, and 3,3,3-trifluoropropyl group, and among them, methyl group is preferable in terms of heat resistance.

The aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 10 carbon atoms. Specifically, examples include phenyl group, naphthyl group, tolyl group, xylyl group, mesityl group, and halogen-substituted aryl groups such as chlorophenyl group, and phenyl group is preferred.

The H group may be a hydrogen atom bonded to a silicon atom (H group in a hydrosilyl group (Si-H group)). The silicone polymer having an H group may have a substituted or unsubstituted monovalent hydrocarbon group excluding an aliphatic unsaturated hydrocarbon group. The substituted or unsubstituted monovalent hydrocarbon group excluding the aliphatic unsaturated hydrocarbon group may have, for example, 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. The monovalent hydrocarbon group may be linear, branched, or cyclic. Specific examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, aliphatic saturated monovalent hydrocarbon groups such as straight-chain or branched alkyl groups such as n-hexyl group, and cycloalkyl groups such as cyclohexyl group; Aryl groups such as phenyl group and tolyl group; Aromatic or aromatic group-containing monovalent hydrocarbon groups such as aralkyl groups such as benzyl group and phenylethyl group; Examples include halogen-substituted monovalent hydrocarbon groups such as 3,3,3-trifluoropropyl group, and cyano-substituted monovalent hydrocarbon groups such as cyanoethyl group, and among these, methyl group is preferable.

The silicone polymer having an H group is preferably blended in an amount such that the molar ratio of hydrosilyl group to alkenyl group is, for example, hydrosilyl group/alkenyl group = 0.5 to 2, and especially is preferably blended in an amount such that it is 1 to 1.2. . Within this range, the curability of the composition and the hardness of the resulting cured product tend to be excellent.

Examples of the photoactivated catalyst include platinum group metal catalysts (hereinafter also referred to as platinum group metal catalysts for simplicity) that are activated by light with a wavelength of 200 to 500 nm. A platinum group metal catalyst is a catalyst that is inactive under light blocking and changes into an active platinum group metal catalyst at room temperature by irradiating light with a wavelength of 200 to 500 nm. The platinum group metal catalyst is a catalyst for promoting the hydrosilylation reaction between an alkenyl group in a silicone polymer having an alkenyl group and a hydrogen atom bonded to a silicon atom in a silicone polymer having an H group.

Specific examples of platinum group metal catalysts include (η5-cyclopentadienyl)trialiphatic platinum compounds and derivatives thereof. Among them, cyclopentadienyltrimethylplatinum, methylcyclopentadienyltrimethylplatinum and derivatives modified with these cyclopentadienyl groups are preferred. Bis(β-diketonato)platinum compounds can also be used, and preferably bis(acetylacetonato)platinum compounds and derivatives thereof modified with an acetylacetonato group.

The amount of the platinum group metal catalyst in the ultraviolet addition-curable silicone adhesive composition is not limited as long as it is an amount that promotes curing (hydrosilylation reaction) of the composition, and is about the total mass of the silicone polymer having an alkenyl group and the silicone polymer having an H group. In terms of mass, the platinum group metal atoms in the composition may be, for example, 0.01 ppm or more and 500 ppm or less, preferably 0.05 to 100 ppm, and more preferably 0.01 to 50 ppm.

The ultraviolet addition-curable silicone adhesive composition includes an adhesion aid, a reaction control agent, and a thixotropic control agent such as fumed silica; reinforcing agents such as crystalline silica; Antioxidants; light stabilizer; Heat resistance improvers such as metal oxides and metal hydroxides; Colorants such as titanium oxide; Fillers for imparting thermal conductivity such as alumina and crystalline silica; Viscosity modifiers such as non-reactive silicone oil without a reactive functional group; Conductivity imparting agents such as metal powders such as silver and gold; It may further contain pigments, dyes, etc. for coloring.

Examples of the adhesion aid include organic compounds containing at least one functional group group consisting of a (meth)acrylic group, a carbonyl group, an epoxy group, an alkoxysilyl group, and an amide group in one molecule. Specific examples of adhesive aids containing an alkoxysilyl group include γ-(glycidoxypropyl)trimethoxysilane (product name: KBM-403, manufactured by Shinetsu Chemical Co., Ltd.), γ-(methacryloxypropyl)trimethoxysilane (product name: KBM-403, manufactured by Shinetsu Chemical Co., Ltd.) Methoxysilane (brand name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.), hydrolyzed condensates thereof, and the like. In addition, specific examples of compounds containing at least one of the above functional group groups and an organosiloxane skeleton include those represented by the following structural formula.

[Formula 1]

(In the formula, Me refers to a methyl group.)

In addition, specific examples of adhesion aids that do not contain an organosiloxane skeleton include allyl glycidyl ether, vinylcyclohexene monooxide, diethyl 2-allyl malonate, allyl benzoate, diallyl phthalate, tetraallyl pyromellitate, and tri-allyl ester. Allyl isocyanurate, etc. can be mentioned.

Specific examples of reaction control agents include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 1-ethynylcyclo. Hexanol, ethynylmethyldecylcarbinol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy- 1-hexyne, 1-ethynyl-1-trimethylsiloxycyclohexane, bis(2,2-dimethyl-3-butynoxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5 , 7-tetravinylcyclotetrasiloxane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, etc., preferably 1-ethynylcyclohexanol and ethynylmethyldecylcar. Binol, 3-methyl-1-butyn-3-ol, etc.

As an ultraviolet addition curing type silicone adhesive composition, those described in, for example, Japanese Patent Application Laid-Open No. 2020-055945 and Japanese Patent Application Laid-Open No. 2020-117654 can be used. Additionally, a commercially available ultraviolet addition curable silicone adhesive composition can be used. Examples of commercially available ultraviolet addition-curable silicone adhesive compositions include KER-4550, KER-4410, KER-4510, KER-4690-A/B, KER-4691-A/B (manufactured by Shinetsu Chemical Co., Ltd.), etc. I can hear it.

[Transparent member]

Examples of the transparent member 22 include a front plate (window layer) and a touch panel. As the front plate, a front plate with appropriate mechanical strength and thickness is used. Examples of such a front plate include a transparent resin plate such as polyimide resin, acrylic resin, or polycarbonate resin, or a glass plate. A functional layer such as an anti-reflection layer may be laminated on the viewing side of the front plate. Additionally, when the front plate is a transparent resin plate, a hard coat layer may be laminated to increase physical strength or a low moisture permeability layer may be laminated to reduce moisture permeability.

As the touch panel, various touch panels such as resistive type, capacitive type, optical type, and ultrasonic type, as well as glass plates and transparent resin plates with a touch sensor function, are used. When a capacitive touch panel is used as a transparent member, it is preferable that a front plate made of glass or a transparent resin plate be installed closer to the viewing side than the touch panel.

[Method for manufacturing laminate]

The manufacturing method of the laminate includes an application process, an ultraviolet irradiation process, a curing process, and a bonding process, and each process can use, for example, the method shown below.

(A) Application process

In the application process, the ultraviolet addition curable silicone adhesive composition can be applied to one substrate. The application method is not particularly limited, and examples include application using a slit coat, DAM-Fill method, fishbone method, etc. In the DAM-Fill method, for the purpose of preventing the ultraviolet addition curing type silicone adhesive composition from spreading before curing, a dam material is installed to surround the periphery of the image display panel, a transparent member is placed on the dam material, and ultraviolet rays are added. This may be a method of injecting a curable silicone adhesive composition. After injection of the ultraviolet addition-curable silicone adhesive composition, alignment and defoaming are performed as necessary, and then curing is performed by irradiation with ultraviolet rays.

The amount of application of the ultraviolet addition-curable silicone adhesive composition to the substrate may be such that the thickness of the ultraviolet addition-curable silicone adhesive layer after curing is, for example, 10 μm or more and 1000 μm or less.

Before applying the ultraviolet addition-curable silicone adhesive composition, the joint surface may be activated by a known pretreatment process such as primer treatment, plasma treatment, or excimer light treatment.

(B) Ultraviolet irradiation process

In the ultraviolet irradiation process, ultraviolet rays can be irradiated to the ultraviolet addition-curable silicone adhesive composition. Examples of the ultraviolet ray irradiation method include a method of irradiating an appropriate amount of ultraviolet rays using a 365 nm UV-LED lamp, metal halide lamp, etc. as an ultraviolet light source.

For ultraviolet irradiation, light with a wavelength of preferably 200 to 500 nm, more preferably 200 to 380 nm, is used. At this time, from the viewpoint of curing speed and discoloration prevention, the irradiation temperature is preferably 20 to 80°C, the irradiation intensity is preferably 30 to 2000 mW/cm2, and the irradiation dose is preferably 150 to 10000 mJ/cm2.

(C) Curing process

In the curing process, the ultraviolet addition-curable silicone adhesive composition irradiated with ultraviolet rays can be cured. Examples of the curing method include a method of curing an ultraviolet addition-curing silicone adhesive composition irradiated with ultraviolet rays by leaving it still in a predetermined environment to form an ultraviolet addition-curing silicone adhesive layer. The curing temperature of the ultraviolet addition-curable silicone adhesive composition is not particularly limited, but is preferably cured at 20 to 80° C. for 1 minute to 1 day in an air atmosphere.

(D) Bonding process

In the bonding process, the other substrate is laminated on the ultraviolet addition-curable silicone adhesive composition or the ultraviolet addition-curable silicone adhesive layer to form a laminate in which the two substrates are joined through the adhesive composition or the ultraviolet addition-curable silicone adhesive layer. As a bonding method, an ultraviolet addition-curable silicone adhesive layer-based laminate that has gone through a coating process, an ultraviolet irradiation process, and a curing process into a liquid or semi-solid state, an adhesive composition after an application process, or an ultraviolet addition-curable silicone adhesive composition after an application process and an ultraviolet irradiation process. The silicone adhesive composition-substrate laminate is placed in a vacuum or atmospheric pressure bonding device, and the other substrate is laminated and bonded on the ultraviolet addition-curing silicone adhesive composition or the ultraviolet addition-curing silicone adhesive layer, in the case of the ultraviolet addition-curing silicone adhesive composition. Examples include a method of performing the remaining processes and curing to form a laminate.

The ultraviolet addition curing type silicone adhesive composition is not inhibited by curing by oxygen and the curing time after irradiation with ultraviolet rays can be changed depending on the design of the adhesive composition or the heating temperature, so it can be used in flat displays, curved displays, etc. The order of the coating process, ultraviolet irradiation process, curing process, and bonding process can be freely selected and changed according to the structure of the device being manufactured.

The manufacturing method of the laminated body will be explained by taking the manufacturing method of the laminated body including the above-described polarizing plate and the front plate as a specific example. First, an ultraviolet addition-curable silicone adhesive composition is applied on the hard coat layer of the polarizing plate. Afterwards, using a UV-LED lamp whose maximum intensity is around a wavelength of 365 nm, an irradiation intensity of 30 to 2,000 mW/cm2 (e.g., 100 mW/cm2) and a dose of 150 to 10,000 mJ/ are applied, using 365 nm light as an indicator. The ultraviolet addition-curable silicone adhesive composition is irradiated with ultraviolet rays at 20 to 80°C (e.g., 23°C) for 1 second to 1 hour (e.g., 30 seconds) to obtain a concentration of cm2 (e.g., 3000 mJ/cm2). Subsequently, the ultraviolet addition-curable silicone adhesive composition is cured by leaving it in an environment of 20 to 80°C (e.g., 23°C) for 1 minute to 1 day (e.g., 30 minutes) to form an ultraviolet addition-curable silicone adhesive layer. Thereafter, by laminating the front plate on the ultraviolet addition-curing silicone adhesive layer using a vacuum bonding device, a laminate in which the polarizer and the front plate are bonded through the ultraviolet addition-curing silicone adhesive layer can be obtained. In addition, after the ultraviolet irradiation process, the front plate is laminated on the ultraviolet addition-curing silicone adhesive composition using a vacuum bonding device, thereby bonding the polarizer and the front plate through the ultraviolet addition-curing silicone adhesive composition, and continuing at 20 to 100°C ( For example, the ultraviolet addition-curable silicone adhesive composition may be cured by leaving it in an environment at 60°C for 1 minute to 1 day (eg, 30 minutes). When the front plate is transparent, vacuum bonding may be performed after the application process, and then ultraviolet rays may be irradiated over the front plate for curing. Alternatively, an ultraviolet addition-curable silicone adhesive composition previously irradiated with ultraviolet rays may be applied to the image display panel, vacuum bonded to the cover panel, and cured.

[Use of laminate]

The laminate 20 is used in various image display devices such as liquid crystal display devices and organic EL display devices. An example of an image display device is a configuration having an image display cell, an adhesive layer laminated on the viewer-side surface of the image display cell, and a polarizing plate laminated on the viewer-side surface of the adhesive layer. This image display device may further include an ultraviolet addition-curing silicone adhesive layer laminated on the viewing side surface of the polarizing plate, and a transparent member laminated on the surface of the ultraviolet addition-curing silicone adhesive layer. In particular, in the laminate of the present embodiment, a transparent member is disposed on the viewing side of the image display device, the polarizing plate and the image display cell are bonded to each other by an adhesive layer, and the polarizing plate and the transparent member are bonded to each other by an ultraviolet addition curing type silicone adhesive layer. It is suitably used in an image display device having an interlayer filling configuration. In addition, the member used for bonding the polarizing plate and the image display cell is not limited to the adhesive layer, and may be an adhesive layer.

[Image display cell]

Examples of image display cells include liquid crystal cells and organic EL cells. As the liquid crystal cell, any of a reflective liquid crystal cell using external light, a transmissive liquid crystal cell using light from a light source such as a backlight, or a transflective semi-reflective liquid crystal cell using both light from the outside and light from the light source may be used. When the liquid crystal cell uses light from a light source, the image display device (liquid crystal display device) has a polarizing plate disposed on the side opposite to the viewing side of the image display cell (liquid crystal cell), and a light source is also disposed. It is preferable that the polarizing plate on the light source side and the liquid crystal cell are bonded through an appropriate adhesive layer. As a driving method for the liquid crystal cell, for example, any type such as VA mode, IPS mode, TN mode, STN mode, or bend orientation (π type) can be used.

As an organic EL cell, one in which a transparent electrode, an organic light-emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescence light emitter) is suitably used. The organic light-emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer containing a triphenylamine derivative, etc., and a light-emitting layer containing a fluorescent organic solid such as anthracene, or a laminate of these light-emitting layers and a perylene derivative, etc. Various layer configurations may be employed, such as a laminate of an electron injection layer including a hole injection layer, a light emitting layer, and an electron injection layer.

[Conjugation of image display cell and polarizer]

An adhesive layer (adhesive sheet) is suitably used to bond an image display cell and a polarizing plate. Among them, the method of bonding the above-described polarizing plate with an adhesive layer to an image display cell is preferable from the viewpoint of workability and the like. An organic solvent dilution of the adhesive composition may be applied on an image display cell to form an adhesive layer, which may then be bonded to a polarizing plate.

Example

Hereinafter, the present invention will be described in detail based on examples. Materials, reagents, amounts of substances, ratios, operations, etc. shown in the examples below can be appropriately changed as long as they do not deviate from the spirit of the present invention. Accordingly, the present invention is not limited to the following examples. “%” and “part” in the examples are mass% and mass part, unless otherwise specified.

[Measurement of curing time of ultraviolet addition-curable silicone adhesive composition]

Referring to FIG. 4, the procedure for measuring the curing time of the ultraviolet addition-curable silicone adhesive composition will be described. The polarizing plate 44 obtained in the examples and comparative examples was molded to a diameter of 11 mm, and an ultraviolet addition-curing silicone adhesive composition (“KER-4550” manufactured by Shinetsu Chemical Co., Ltd.) was applied on the hard coat layer. In the drawing, the adhesive (40)) was added dropwise to the ultraviolet addition curable silicone adhesive composition, and a polarizer sample was produced by irradiating ultraviolet rays to a light quantity of 3000 mJ/cm2 using a 365 nm UV-LED [Figure 4] (a)].

After that, disk-shaped jigs 1 to 3 (symbols 41 to 43) with a diameter of 11 mm for setting the polarizing plate sample in a dynamic viscoelasticity measuring device (“DMA/SDTA861” manufactured by METTLER TOLEDO) were prepared. The polarizer sample is fixed to the protrusions (not shown) of jig 1 and jig 3 so that the polarizer side of the polarizer sample is on the jig 1 and jig 3 sides, respectively, and the adhesive layer side of the polarizer sample fixed on jig 1 and jig 3 is jig 2. Jig 2 was inserted into contact with the jig 1 and jig 3, and the thickness of the adhesive layer was adjusted to 500 ㎛ by adjusting the jig spacing adjustment screw (not shown) provided in jig 1 and jig 3 [FIG. 4(b)].

Jig 1, polarizer sample, jig 2, polarizer sample, and jig 3 were stacked in that order and set in a dynamic viscoelasticity measuring device, and the curing time of the ultraviolet addition-curable silicone adhesive composition was measured under the following measurement conditions. In addition, the time from irradiating ultraviolet rays to setting the polarizing plate and starting to measure the curing time was commonly set to 5 minutes in each Example and Comparative Example. This time is not included in the curing time in Table 2. The definition of curing time is as described above.

frequency : 1㎐

amount of deformation : 4%

temperature : 80℃

[Measurement of absorbance of hard coat layer]

Absorbance at a wavelength of 300 nm and 365 nm was measured using a spectrophotometer U-2500PC manufactured by Hitachi Seisakusho Co., Ltd. Additionally, the absorbance of the hard coat layer is expressed by the following equation:

Absorbance of hard coat layer = (absorbance of hard coat film) - (absorbance of transparent film substrate)

It was calculated using .

[Preparation of composition for forming hard coat layer]

The components shown in Table 1 were mixed and stirred in the ratio shown in Table 1 to obtain compositions HC-1 to HC-4 for forming a hard coat layer.

Unit: parts by mass

Photocurable resin: Beamset 710 (pentaerythritol polyacrylate), manufactured by Arakawa Kagaku Kogyo Co., Ltd.

Photopolymerization initiator A: Omnirad2959, manufactured by IGM Resins

Photopolymerization initiator B: Omnirad369E, manufactured by IGM Resins

Photopolymerization initiator C: Omnirad907, manufactured by IGM Resin

Solvent: Methyl ethyl ketone

[Production of hard coat film (11)]

On a transparent film substrate (triacetylcellulose-based resin film, thickness 40 μm), the composition HC-1 for forming a hard coat layer was applied by a bar coating method so that the film thickness after drying was about 6 μm. The coating film was dried in an oven at 60°C for 150 seconds. Using an electrodeless lamp H bulb manufactured by Fusion, ultraviolet rays with an illumination intensity of 400 mW/cm2 and a light quantity of 300 mJ/cm2 were irradiated to the coating film to form a hard coat layer, thereby obtaining a hard coat film (11). The absorbance of the hard coat layer of the hard coat film 11 was measured.

[Production of hard coat films 12 to 14]

In the production of the hard coat film 11, the same procedure as in the production of the hard coat film 11 was carried out, except that the composition HC-1 for forming the hard coat layer was changed to the composition HC-2 to HC-4 for forming the hard coat layer. Thus, hard coat films 12 to 14 were produced. The absorbance of the hard coat layer of the obtained hard coat film was measured.

<Example 1>

[Saponification treatment of film]

The hard coat film 11 and the transparent film substrate were immersed in a 1.5 mol/L NaOH aqueous solution (saponification solution) maintained at 55°C for 2 minutes, and then the film was washed with water. Afterwards, the film was immersed in a 0.05 mol/L sulfuric acid aqueous solution at 25°C for 30 seconds, and then passed through a water washing bath under running water for 30 seconds to bring the film into a neutral state. Then, water removal using an air knife was repeated three times to drop the water, and then the water was left in a drying zone at 70°C for 15 seconds to dry, and a saponification treatment was performed.

[Production of polarizer]

A saponified hard coat film (11) and a saponified transparent film substrate were laminated on both sides of the iodine-PVA-based polarizer via a PVA-based adhesive. In addition, the surface of the hard coat film 11 after saponification on which the hard coat layer was not formed was made to be the bonding surface with the iodine-PVA-based polarizer. It was heated and dried to obtain the polarizing plate of Example 1. The results are shown in Table 2.

<Examples 2, 3 and Comparative Example 1>

A polarizing plate was produced in the same manner as in Example 1 except that the hard coat film shown in Table 1 was used instead of the hard coat film 11 in Example 1. The results are shown in Table 2.

From the results in Table 2, in the polarizing plates of Examples 1 to 3 in which the hard coat layer had an absorbance of 4.5 or less at a wavelength of 300 nm, the ultraviolet addition-curable silicone adhesive composition could be cured in a relatively short time. In contrast, in the polarizing plate of Comparative Example 1 in which the hard coat layer had an absorbance of more than 4.5 at a wavelength of 300 nm, the ultraviolet addition-curable silicone adhesive composition could not be cured within 60 minutes. According to the present invention, it can be seen that a polarizing plate is provided that can sufficiently cure an ultraviolet addition-curable silicone adhesive composition within a certain period of time.

10: Polarizer
11: Polarizer
12: Hard coat layer
13: Thermoplastic resin film
20: Laminate
21: UV addition curing silicone adhesive layer
22: Transparent member
A: Starting point of dynamic viscoelasticity measurement
B: The point at which G' and G'' become equal.
30: UV irradiation
31: Gelation point
40: Adhesive
41: Jig 1
42: Jig 2
43: Jig 3
44: Polarizer

Claims (9)

A polarizing plate comprising a polarizer and a hard coat layer, wherein the hard coat layer constitutes at least one outermost surface of the polarizing plate, and the hard coat layer has an absorbance of 4.5 or less at a wavelength of 300 nm. The method of claim 1, wherein the hard coat layer is made of a cured layer of a photocurable resin composition,
The photocurable resin composition is a polarizing plate containing a radical polymerization initiator as a photopolymerization initiator. The polarizing plate according to claim 1 or 2, wherein the cured layer of the photocurable resin composition includes a cured product of a (meth)acrylic resin. The polarizing plate of claim 2, wherein the radical polymerization initiator is an α-hydroxyacetophenone-based photopolymerization initiator or an α-aminoacetophenone-based photopolymerization initiator. The polarizing plate according to any one of claims 1 to 4, wherein the hard coat layer has a thickness of 0.5 μm or more and 10 μm or less. The polarizing plate according to any one of claims 1 to 5,
Provided with a transparent member,
A laminate in which the hard coat layer and the transparent member are laminated through an ultraviolet addition-curing silicone adhesive layer. The laminate according to claim 6, wherein the ultraviolet addition curable silicone adhesive layer has a thickness of 10 ㎛ or more and 1000 ㎛ or less. The laminate according to claim 6 or 7, wherein the ultraviolet addition-curing silicone adhesive layer is a cured layer of an ultraviolet addition-curing silicone adhesive composition. The laminate according to any one of claims 6 to 8, wherein the transparent member is a glass plate, a transparent resin plate, or a touch panel.