JP2021028703A - Easy-adhesion film, manufacturing method thereof, polarization plate and picture display unit - Google Patents

Abstract

To provide an easy-adhesion film capable of exhibiting high adhesion to a film such as a polarizer, difficult to cause blocking, and excellent in homogeneity and durability .SOLUTION: An easy-adhesion film (1) includes an easy-adhesion layer (15) on a surface of a transparent film base material (11). The easy-adhesion layer (15) includes a binder resin and fine particles. Thickness of the easy-adhesion layer is preferably 120 to 260 nm. An average primary particle diameter of the fine particles is preferably 0.1 to 0.9 time the thickness of the easy-adhesion layer. An easy-adhesion layer can be formed through applying onto the transparent film base material and heating an easy-adhesion composition containing the binder resin or a precursor substance thereof, the fine particles, an alkaline component and solvent.SELECTED DRAWING: Figure 1

Description

The present invention relates to an easy-adhesive film provided with an easy-adhesive layer on the surface of a transparent film base material and a method for producing the same. Further, the present invention relates to a polarizing plate in which an easily adhesive film is bonded to the surface of a polarizing element, and an image display device including the polarizing plate.

Liquid crystal display devices and organic EL display devices are widely used as various image display devices such as mobile devices, car navigation devices, personal computer monitors, and televisions. Due to the display principle of the liquid crystal display device, a polarizing plate is arranged on the visible surface of the liquid crystal cell. In a transmissive liquid crystal display device, polarizing plates are arranged on both sides of the liquid crystal cell. In an organic EL display device, in order to prevent external light from being reflected by a metal electrode (cathode) and visually recognized as a mirror surface, a circularly polarizing plate (typically, a polarizing plate and 1 /) are formed on the viewing side surface. A laminated body of four wave plates) may be arranged.

Generally, the polarizing plate is provided with a transparent film (polarizer protective film) for the purpose of protecting the polarizing element on one side or both sides of the polarizer. As the polarizer, one in which iodine is adsorbed on a polyvinyl alcohol (PVA) -based film and the molecules are oriented by stretching or the like is widely used.

As the polarizer protective film to be attached to the surface of the polarizer, a cellulose-based film such as cellulose acetate is widely used because of its excellent adhesiveness to the PVA-based polarizer. As the transparent protective film, a film made of a resin material such as acrylic, polyester, polycarbonate, or cyclic polyolefin has also been used. Films made of these resin materials have lower moisture permeability than cellulosic films, and polarizing plates with a low moisture permeability resin film bonded to the surface of the polarizer are subject to long-term exposure to a high humidity environment. However, the change in optical characteristics is small, and it tends to be excellent in durability.

On the other hand, a film made of a resin material such as acrylic, polyester, polycarbonate, or cyclic polyolefin tends to have lower adhesiveness to a PVA-based polarizer than a cellulose-based film. Therefore, a method has been proposed in which an easy-adhesion layer is provided on the surface of a transparent film used as a polarizer protective film to improve the adhesiveness with a polarizer.

For example, in Patent Document 1, an easy-adhesive film provided with an easy-adhesive layer containing fine particles and a binder resin on the surface of an acrylic film has excellent adhesion to a polarizer and is used when the film is wound into a roll. It is described that blocking can be suppressed. In the example of Patent Document 1, an easy-adhesion film provided with a urethane easy-adhesion layer having an average thickness of 400 nm (thickness range of 300 to 500 nm) containing 1 to 7% by weight of silica particles having an average primary particle diameter of 35 nm on the surface of the acrylic film. Is shown as an example of using as a polarizer protective film. Patent Document 2 describes that the blocking resistance is improved when the average primary particle size of the fine particles contained in the easy-adhesion layer is larger than 200 nm.

Patent No. 5354733 Japanese Unexamined Patent Publication No. 2012-32768

As image display devices become larger and brighter, the polarizing plates that make up image display devices have small changes in optical characteristics even in harsher environments (for example, higher temperature and higher humidity conditions). It is now required. The polarizing plate using the easy-adhesion film described in Patent Document 1 and Patent Document 2 as the polarizer protective film has excellent adhesiveness between the polarizer and the polarizer protective film, and has high adhesive reliability. However, it has been newly found that the polarizing plate using these easy-adhesive films as a polarizer protective film may cause unevenness and deterioration of display characteristics when exposed to a high humidity environment for a long time.

In view of the above problems, the present invention has excellent adhesion to a polarizer or the like, blocking is unlikely to occur, and even when exposed to a high temperature and high humidity environment for a long time, optical defects such as unevenness are unlikely to occur. The purpose is to provide a film.

As a result of studies by the present inventors in view of the above problems, it is found that alkaline components such as ammonia and amines added to the easy-adhesion composition for the purpose of improving the dispersibility of fine particles remain in the easy-adhesion layer. It has been found that this is one of the causes of the decrease in durability in a humid environment, and that the above problem can be solved by setting the amount of residual alkali in the easy-adhesion layer within a predetermined range.

The present invention relates to an easy-adhesive film provided with an easy-adhesive layer on the surface of a transparent film base material and a method for producing the same. The easy-adhesion layer contains a binder resin and fine particles. The thickness of the easy-adhesion layer is preferably 120 to 260 nm. The average primary particle size of the fine particles contained in the easy-adhesion layer is preferably 0.1 to 0.9 times the thickness of the easy-adhesion layer. The average primary particle size of the fine particles is 10 nm or more, preferably 100 to 200 nm. The content of the alkaline component of the easy-adhesion layer is preferably 200 ppm or less, and the total content of amine and ammonia is preferably 200 ppm or less.

An acrylic film or the like is used as the transparent film base material. Urethane-based resin or the like is used as the binder resin for the easy-adhesion layer. The content of the fine particles in the easy-adhesion layer is preferably about 8 to 50% by weight. The fine particles of the easy-adhesion layer may be embedded in the transparent film base material.

The easy-adhesion layer is formed by applying the easy-adhesion composition to the surface of the transparent film base material and heating it. The easy-adhesion composition contains a binder resin or a precursor thereof, fine particles, an alkaline component and a solvent. Since the easy-adhesion composition contains an alkaline component, the dispersibility of the fine particles is improved, and an easy-adhesion film having excellent slipperiness can be obtained. The alkaline component can also act as a catalyst for promoting the reaction of the binder resin (precursor). From the viewpoint of promoting volatilization of the alkaline component by heating, the boiling point of the alkaline component is preferably 150 ° C. or lower. Examples of the alkaline component include amines and ammonia.

By raising the heating temperature after applying the easy-adhesion composition, volatilization of the alkaline component can be promoted, and an easy-adhesion layer having a small amount of residual alkaline component can be formed. For example, the easy-adhesion composition may be heated at a temperature higher than the glass transition temperature of the transparent film substrate by 10 ° C. or more. By increasing the heating temperature, a region in which fine particles of the easy-adhesion layer are embedded in the transparent film base material is likely to be formed, and the adhesion between the transparent film base material and the easy-adhesion layer tends to be improved.

After applying the easy-adhesion composition on the transparent film base material, stretching may be performed while heating the transparent film base material. In particular, by stretching the transparent film base material while heating the easy-adhesion composition at a temperature 10 ° C. or higher higher than the glass transition temperature of the transparent film base material, the adhesion between the transparent film base material and the easy-adhesion layer is improved. Tend to do.

The above-mentioned easy-adhesive film has excellent adhesiveness to other films, glass substrates, and the like. The easy-adhesive film can be used, for example, as a polarizer protective film. For example, a polarizing plate can be obtained by adhering an easy-adhesive film to the surface of a polyvinyl alcohol-based polarizing element via an adhesive layer. An image display device can be formed by arranging a polarizing plate on the surface of an image display cell such as a liquid crystal display cell or an organic EL cell.

The easy-adhesive film of the present invention is less likely to cause blocking and is less likely to cause optical defects even when exposed to a high temperature and high humidity environment for a long time. Therefore, it is suitably used as a film for a display device such as a polarizer protective film. Be done.

It is sectional drawing which shows the structural example of the easy-adhesion film. It is sectional drawing which shows the structural example of the polarizing plate.

FIG. 1 is a schematic cross-sectional view showing a configuration example of an easily adhesive film according to an embodiment of the present invention. The easy-adhesion film 1 is provided with an easy-adhesion layer 15 on at least one surface of the film base material 11. Easy-adhesion layers may be provided on both sides of the film substrate. The easy-adhesive film is used by being bonded to another film, a glass substrate, or the like.

As a form of use of the easy-adhesion film, a polarizer protective film can be mentioned. FIG. 2 is a cross-sectional view showing a configuration example of a polarizing plate including the easy-adhesion film 1 as a polarizer protective film. The polarizing plate 100 includes an easy-adhesion film 1 bonded to one surface (first main surface) of the polarizer 5 via an adhesive layer 6. In the polarizing plate 100 shown in FIG. 2, the easy-adhesion film 1 has an easy-adhesion layer 15 on the bonding surface of the film base material 11 with the polarizing element 5. An easy-adhesion layer may be provided on the surface to which the polarizer 5 is not bonded. In the polarizing plate 100 shown in FIG. 2, a transparent protective film 2 is attached to the other surface (second main surface) of the polarizer 5 via an adhesive layer 7.

[Easy adhesive film]
The easy-adhesion film 1 includes an easy-adhesion layer 15 on at least one surface of the film base material 11.

<Film base material>
A transparent film is preferable as the film base material 11. The total light transmittance of the transparent film substrate is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more. Examples of the resin material constituting the film base material 11 include acrylic resin, polyester resin, polycarbonate resin, polyolefin resin, cyclic polyolefin resin, polystyrene resin, polyamide resin, and polyimide resin. When the easy-adhesion film is used as an optically isotropic polarizing element protective film, an acrylic resin or a cyclic polyolefin resin is preferable as the resin material of the film base material 11 because the birefringence is small, and the acrylic resin is preferable. Especially preferable.

Examples of the cyclic polyolefin resin include polynorbornene. Examples of commercially available cyclic polyolefin resins include Zeonoa and Zeonex manufactured by Zeon Corporation, Arton manufactured by JSR, Appel manufactured by Mitsui Chemicals, and Topas manufactured by TOPAS ADVANCED POLYMERS. The cyclic polyolefin-based film preferably contains 50% by weight or more of the cyclic olefin-based resin.

Examples of the acrylic resin include poly (meth) acrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate- (meth) acrylic acid ester copolymers, and methyl methacrylate. -Acrylic acid ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having alicyclic hydrocarbon group (for example, methyl methacrylate-methacrylic acid) Cyclohexyl copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.) can be mentioned.

As used herein, the term "(meth) acrylic" means acrylic and / or methacrylic. Acrylic resins include those containing acrylic acid or a derivative thereof as a constituent monomer component, and those containing methacrylic acid or a derivative thereof as a constituent monomer component.

As the acrylic resin, the acrylic resin having a glutaric acid anhydride structure described in JP-A-2006-283013, JP-A-2006-335902, JP-A-2006-274118, etc .; and / or JP-A. Acrylic resins having a lactone ring structure described in JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, JP-A-2005-146804, etc. You may use it. Acrylic resins having a glutaric anhydride structure and acrylic resins having a lactone ring structure have high heat resistance, high transparency, and high mechanical strength, and thus have a high degree of polarization and excellent durability. Suitable for manufacturing.

When the film base material 11 is an acrylic film, the content of the acrylic resin in the film base material is preferably 50% by weight or more, more preferably 60 to 98% by weight, still more preferably 70 to 97% by weight. The acrylic film may contain a thermoplastic resin other than the acrylic resin. For example, by blending another thermoplastic resin, the birefringence of the acrylic resin is canceled and an acrylic film having excellent optical isotropic properties can be obtained. Further, a thermoplastic resin other than the acrylic resin may be blended for the purpose of improving the mechanical strength of the film.

Thermoplastic resins other than acrylic resins include olefin-based polymers, vinyl halide-based polymers, polystyrene, styrene and acrylic monomer and copolymers, polyester, polyamide, polyacetal, polycarbonate, polyphenylene oxide, polyphenylene sulfide, and poly. Examples thereof include ether ether ketone, polysulfone, polyethersulfone, polyoxybenzylene, polyamideimide, and rubber-based polymers.

The film substrate 11 may contain additives such as antioxidants, stabilizers, reinforcing materials, ultraviolet absorbers, flame retardants, antistatic agents, colorants, fillers, plasticizers, lubricants and fillers. The resin material and the additive or the like may be mixed to prepare a thermoplastic resin composition such as pellets in advance, and then filmed.

The thickness of the film base material 11 is about 5 to 200 μm. From the viewpoint of mechanical strength, transparency, handleability, and the like, the thickness of the film base material 11 is preferably 10 to 100 μm, more preferably 15 to 60 μm.

The glass transition temperature Tg of the film substrate 11 is preferably 100 ° C. or higher, more preferably 110 ° C. or higher. When the film base material 11 is an acrylic film, as described above, by using an acrylic resin having a glutaric acid anhydride structure or an acrylic resin having a lactone ring structure as the acrylic resin, the acrylic film can be obtained. Tg can be increased and heat resistance can be improved. The upper limit of Tg of the film base material 11 is not particularly limited, but is preferably 170 ° C. or lower from the viewpoint of moldability and the like.

Examples of the method for producing the film base material 11 include a solution casting method, a melt extrusion method, a calender method, and a compression molding method. The film base material 11 may be either an unstretched film or a stretched film. When the film base material 11 is an acrylic film, the acrylic film is preferably a stretched film stretched in at least one direction, and a biaxially stretched film is particularly preferable, from the viewpoint of improving mechanical strength. By blending another thermoplastic resin so as to cancel the birefringence of the acrylic resin, an acrylic film having a small retardation and excellent optical isotropic properties can be obtained even when stretched.

<Easy adhesive layer>
The easy-adhesion layer 15 provided on the surface of the film base material 11 contains a binder resin and fine particles. By providing the easy-adhesion layer 15, the adhesiveness to a film such as a polarizer, a glass substrate, or the like can be improved. Since the easy-adhesion layer 15 contains fine particles, fine irregularities are formed on the surface of the easy-adhesion layer 15, and the slipperiness of the film is improved. Therefore, it contributes to the reduction of scratches when the easy-adhesive film 1 is conveyed in a roll and the suppression of blocking when the film is wound into a roll.

(Binder resin)
As the binder resin, since it has excellent adhesion to a film base material such as an acrylic film, it has cross-linking properties such as polyurethane resin, epoxy resin, isocyanate resin, polyester resin, polymers containing an amino group in the molecule, and oxazoline group. A resin (polymer) having a reactive group such as an acrylic resin having a functional group is used. As the binder resin of the easy-adhesion layer 15, a polyurethane resin is particularly preferable. The easy-adhesion layer 15 containing the polyurethane resin binder has high adhesion to the film base material 11. Further, the easy-adhesive film 1 in which the easy-adhesive layer 15 contains a polyurethane resin binder tends to exhibit high adhesiveness when a film such as a polarizer is laminated via an adhesive layer.

Urethane resins are typically reaction products of polyols and polyisocyanates. As the polyol component, a polymer polyol such as a polyacrylic polyol, a polyester polyol, or a polyether polyol is preferably used.

The polyacrylic polyol is typically obtained by polymerizing a (meth) acrylic acid ester with a hydroxyl group-containing monomer. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate and the like. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and (meth). Hydroxyalkyl esters of (meth) acrylic acids such as 4-hydroxybutyl acrylate and 2-hydroxypentyl (meth) acrylate; (meth) acrylic acid monoesters of polyhydric alcohols such as glycerin and trimethylpropane; N-methylol Examples include (meth) acrylamide.

The polyacrylic polyol may contain a monomer component other than the above. Other monomer components include unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid and their anhydrides and diesters; unsaturated nitriles such as (meth) acrylonitrile; (meth). Unsaturated amides such as acrylamide and N-methylol (meth) acrylamide; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether; α-olefins such as ethylene and propylene; vinyl chloride and vinylidene chloride Halogenized α, β-unsaturated aliphatic monomers such as styrene, α-unsaturated aromatic monomers such as styrene and α-methylstyrene, and the like.

The polyester polyol is typically obtained by the reaction of a polybasic acid with the polyol. Examples of the polybasic acid include aromatics such as orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and tetrahydrophthalic acid. Dicarboxylic acid; oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decandicarboxylic acid, dodecandicarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkylsuccinic acid, linoleic acid , Maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid and other aliphatic dicarboxylic acids; hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and other alicyclics. The formula dicarboxylic acid; or a reactive derivative such as these acid anhydrides, alkyl esters, acid halides and the like can be mentioned.

Examples of the polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6-hexanediol, 1 , 8-octanediol, 1,10-decanediol, 1-methyl-1,3-butylene glycol, 2-methyl-1,3-butylene glycol, 1-methyl-1,4-pentylene glycol, 2-methyl -1,4-pentylene glycol, 1,2-dimethyl-neopentyl glycol, 2,3-dimethyl-neopentyl glycol, 1-methyl-1,5-pentylene glycol, 2-methyl-1,5-penti Lene glycol, 3-methyl-1,5-pentylene glycol, 1,2-dimethylbutylene glycol, 1,3-dimethylbutylene glycol, 2,3-dimethylbutylene glycol, 1,4-dimethylbutylene glycol, diethylene glycol, tri Examples thereof include ethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F.

The polyether polyol is typically obtained by ring-opening polymerization of an alkylene oxide on a polyhydric alcohol and adding it. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, and trimethylolpropane. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and tetrahydrofuran.

Examples of the polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate, 2. Aliphatic diisocyanates such as −methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate; isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4′-cyclohexylmethane diisocyanate, 1,4-cyclohexanediisocyanate , Methylcycloheximethylene diisocyanate, alicyclic diisocyanates such as 1,3-bis (isocyanatemethyl) cyclohexane; tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate , 4,4'-Diphenyldimethylmethane diisocyanate, 4,4'-dibenzyldiisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate and other aromatic diisocyanates Examples thereof include aromatic aliphatic diisocyanates such as dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethylxylylene diisocyanate.

The urethane resin constituting the easy-adhesion layer 15 preferably has a carboxy group. Since the urethane resin has a carboxy group, a crosslinked structure can be introduced, and the adhesive durability between the easy-adhesive film 1 and the polarizer or the like tends to be improved. A urethane resin having a carboxy group can be obtained, for example, by reacting a chain lengthing agent having a free carboxy group in addition to a polyol and a polyisocyanate. Examples of the chain length agent having a free carboxy group include dihydroxycarboxylic acid and dihydroxysuccinic acid. Examples of the dihydroxycarboxylic acid include dialkylol alkanoic acids such as dimethylol alkanoic acid (for example, dimethylol acetic acid, dimethylol butanoic acid, dimethylol propionic acid, dimethylol butyric acid, and dimethylol pentanoic acid).

The method for producing the urethane resin is not particularly limited, and either a one-shot method in which the monomer components are reacted at once or a multi-step method in which the monomer components are reacted stepwise may be used. When introducing a carboxy group into a urethane resin using a chain lengthing agent having a free carboxy group, a multi-step method is preferable. When producing the urethane resin, a urethane reaction catalyst may be used if necessary.

The number average molecular weight of the urethane resin is preferably 5,000 to 600,000, more preferably 10,000 to 400,000. The acid value of the urethane resin is preferably 10 to 50, more preferably 20 to 45.

The urethane resin may have a crosslinked structure. By introducing a crosslinked structure into the urethane resin, the adhesive durability between the easy-adhesive film 1 and the polarizer or the like tends to be improved. As the cross-linking agent, one capable of reacting with the cross-linking functional group of the urethane resin can be used without particular limitation. When the urethane resin has a carboxy group, a cross-linking agent containing an amino group, an oxazoline group, an epoxy group, a carbodiimide group and the like is used. Among these, a cross-linking agent having an oxazoline group is preferable. Since the oxazoline group has low reactivity with the carboxy group at room temperature, it has a long pot life when mixed with a urethane resin, and can flexibly respond to the lead time of the process.

The cross-linking agent may be a low molecular weight compound or a polymer. An acrylic polymer is preferable as the cross-linking agent because it has high solubility in an aqueous composition and excellent compatibility with urethane resin. In particular, when an acrylic polymer having an oxazoline group is used as the cross-linking agent, the adhesiveness between the easy-adhesive film 1 and a film such as a polarizer tends to be improved.

The amount of the cross-linking agent used is preferably 1 to 30 parts by weight, more preferably 3 to 20 parts by weight, based on 100 parts by weight of the urethane resin.

(Fine particles)
Since the easy-adhesion layer 15 contains fine particles, a fine uneven shape is formed on the surface of the easy-adhesion layer, the slipperiness of the easy-adhesion film 1 is improved, and blocking can be suppressed. From the viewpoint of forming irregularities that contribute to improving slipperiness and suppressing blocking, the particle size (average primary particle size) of the fine particles is preferably 0.1 times or more, more preferably 0.2 times or more the thickness of the easy-adhesion layer. , 0.3 times or more is more preferable. On the other hand, if the particle size of the fine particles is excessively large, the fine particles may fall off from the easy-adhesion layer, causing poor appearance or blocking. In addition, the fallen particles may adhere to the transport roll or the like and cause dents or scratches. Therefore, the average primary particle size of the fine particles is preferably 0.9 times or less, more preferably 0.8 times or less the thickness of the easy-adhesion layer.

The smaller the average particle size of the fine particles, the less visible light is scattered and the more the transparency tends to be improved. The haze of the easy-adhesion film is preferably less than 2%, preferably less than 1.5%. From the viewpoint of suppressing the increase in haze caused by the fine particles, the average particle size of the fine particles is preferably 250 nm or less, more preferably 200 nm or less. When the easy-adhesion layer having a small thickness is formed, the average particle size of the fine particles is preferably in the above range from the viewpoint of suppressing the fine particles from falling off from the surface of the easy-adhesion layer.

From the viewpoint of enhancing the dispersibility of the fine particles in the easy-adhesion layer and uniformly forming irregularities in the plane, the average particle size of the fine particles is preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more. In particular, since dispersibility can be ensured even with a low amount of alkali and the occurrence of unevenness on the polarizing plate due to residual alkali can be suppressed, the average particle size of the fine particles is preferably 50 nm or more, and particularly preferably larger than 100 nm. preferable.

The fine particles of the easy-adhesion layer 15 may be either inorganic fine particles or organic fine particles. Inorganic fine particles are preferable as the fine particles because they are excellent in dispersibility and uniformity of particle size. Examples of the inorganic fine particles include inorganic oxides such as titania, alumina and zirconia; calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate and the like. Of these, inorganic oxides are preferable. Examples of the organic fine particles include silicone-based resin, fluororesin, and acrylic-based resin. In order to suppress light scattering caused by fine particles, it is preferable that the difference in refractive index between the binder resin (generally about 1.5 refractive index) and the fine particles is small. Silica particles are preferable as the fine particles of the easy-adhesion layer 15 because the difference in refractive index from the binder resin is small and the dispersibility is excellent.

When the easy-adhesion layer 15 is formed from an aqueous composition, it is preferable to use fine particles having high water dispersibility. The aqueous dispersion of fine particles may be blended into the composition. In order to enhance the dispersibility of the fine particles, it is preferable to add an alkaline component such as amine or ammonia to make the easy-adhesion composition weakly alkaline.

Colloidal silica is preferably used as the water-dispersible silica particles. As colloidal silica, Quattron PL series manufactured by Fuso Chemical Industries, Ltd., Snowtex series manufactured by Nissan Chemical Industries, Ltd., AERODISP series and AEROSIL series manufactured by Nippon Aerosil Co., Ltd., and Seahorse Star manufactured by Nippon Shokubai Co., Ltd. Commercially available products such as the KE series may be used.

From the viewpoint of enhancing the slipperiness and blocking resistance of the easy-adhesion film 1 by forming irregularities on the surface of the easy-adhesion layer 15, the content of fine particles in the easy-adhesion layer 15 is preferably 3% by weight or more, preferably 4% by weight or more. Is more preferable. When the thickness of the easy-adhesion layer 15 is small (for example, when it is 260 nm or less), the content of the fine particles is increased to increase the amount of fine particles (number density) per unit area, or the particle size of the fine particles is increased individually. By increasing the size of the unevenness (protrusion) of the surface, the slipperiness and blocking resistance tend to be improved.

If the content of the fine particles in the easy-adhesion layer 15 is excessively large, the optical characteristics may be deteriorated due to the increase in light scattering at the interface between the binder resin and the fine particles. Further, if the content of the fine particles is increased, it may cause a poor appearance due to aggregation of the fine particles and a decrease in adhesiveness due to a decrease in the relative content of the binder resin. Therefore, the content of the fine particles in the easy-adhesion layer 15 is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 30% by weight or less. The content of the fine particles in the easy-adhesion layer 15 may be 20% by weight or less, 15% by weight or less, or 10% by weight or less.

(Residual alkali content)
When an alkaline component such as amine or ammonia is used to enhance the dispersibility of the fine particles, the alkaline component inevitably remains in the easy-adhesion layer. When the easy-adhesive film 1 is used as the polarizer protective film, if the residual alkali amount of the easy-adhesive layer is excessively large, the penetration of the adhesive into the easy-adhesive layer is promoted, and the adhesive layer is formed at the interface with the polarizer. Since it is difficult to form, the adhesive force between the polarizer and the easy-adhesive film may decrease. Further, when the residual alkaline component of the easy-adhesion layer 15 is eluted by moisture or the like, the polarizer may be deteriorated, the degree of polarization of the polarizing plate may be lowered, or optical defects such as unevenness may occur.

From the viewpoint of increasing the adhesive strength of the easy-adhesive film and improving the humidifying durability of the polarizing plate, the residual alkali amount of the easy-adhesive layer 15 is preferably 200 ppm or less, more preferably 150 ppm or less. In particular, from the viewpoint of improving the humidification durability of the polarizing plate, the smaller the residual alkali amount in the easy-adhesion layer 15, the more preferably, the residual alkali amount is preferably 100 ppm or less, and more preferably 75 ppm or less. The amount of residual alkali may be 70 ppm or less, 60 ppm or less, or 55 ppm or less.

On the other hand, if the amount of residual alkali in the easy-adhesion layer 15 is excessively small, the dispersibility of the fine particles is impaired, and appearance defects such as cloudiness due to aggregation of the fine particles may occur. Further, due to the aggregation of fine particles due to the decrease in dispersibility and the dropping of particles from the easy-adhesion layer, appropriate irregularities are not formed on the surface of the easy-adhesion layer, and the slipperiness of the easy-adhesion film tends to decrease. .. Therefore, the residual alkali amount of the easy-adhesion layer 15 is preferably 3 ppm or more, more preferably 5 ppm or more, and even more preferably 10 ppm or more. The amount of residual alkali may be 15 ppm or more, 20 ppm or more, or 25 ppm or more.

Specific examples of the residual alkaline component in the easy-adhesion layer include amines and ammonia, and it is preferable that the total content of amines and ammonia in the easy-adhesion layer is within the above range. The amount of alkali in the easy-adhesion layer can be quantified by liquid chromatography, ion chromatography, or the like, depending on the type of alkaline component. The alkaline component may be quantified by an analytical method (for example, LC / MS) that combines chromatography and mass spectrometry (MS). When a plurality of alkaline components are contained in the easy-adhesion layer, the total of each component is taken as the alkali component content (residual amount) of the easy-adhesion layer.

As described above, the slipperiness and blocking resistance of the easy-adhesion film can be improved by increasing the content of the fine particles or increasing the particle size of the fine particles within a range that does not impair the dispersibility of the fine particles. From the viewpoint of suppressing the aggregation of fine particles, a method of using fine particles having a large particle size is preferable within a range not exceeding 0.9 times or 0.8 times the thickness of the easy-adhesion layer. Even when the amount of particles with a small particle size is increased, the dispersibility can be maintained by increasing the amount of alkali added, but if the amount of alkali added is increased to improve the dispersibility of the fine particles, it remains. Alkali may cause deterioration of the polarizer. Further, if the heat treatment time is lengthened in order to reduce the amount of residual alkali, the productivity may decrease.

Fine particles having a particle size larger than 100 nm show good dispersibility even in a low alkali amount, and are advantageous from the viewpoint of achieving both improvement in slipperiness and blocking resistance and improvement in durability of the polarizing plate. From the viewpoint of maintaining the fixability of the fine particles to the easy-adhesion layer while ensuring the dispersibility of the fine particles, the average primary particle size of the fine particles contained in the easy-adhesion layer is particularly preferably larger than 100 nm and 200 nm or less. ..

<Formation of easy-adhesion layer>
The method for forming the easy-adhesion layer 15 on the surface of the film base material 11 is not particularly limited. Preferably, the easy-adhesion layer 15 is formed by applying an easy-adhesion composition (coating liquid) containing a binder resin and fine particles on the film base material 11 and heating the film base material 11.

(Easy adhesive composition)
The easy-adhesion composition is preferably an aqueous composition using water as a solvent (and a dispersion medium for fine particles). The concentration of the solid content (nonvolatile component) in the easy-adhesion composition is preferably 1 to 30% by weight, more preferably 2 to 20% by weight, still more preferably 3 to 15% by weight.

The water-based easy-adhesion composition contains water as a solvent (and a dispersion medium), a binder resin fat or a precursor thereof, and fine particles. The easy-adhesion composition preferably further contains an alkaline component. As described above, the alkaline component has an action of promoting the dispersion of fine particles.

On the other hand, if the alkali contained in the easy-adhesion composition remains in the easy-adhesion layer, it may cause a decrease in the moisture and heat resistance of the polarizing plate. In particular, a strong alkali such as caustic can cause deterioration of the polarizer even in a small amount. Therefore, as the alkaline component contained in the easy-adhesion composition, a weak alkaline component such as ammonia or amine is preferable. The pH of the easy-adhesion composition (coating liquid) is preferably about 7.5 to 9 from the viewpoint of improving the dispersibility of the fine particles and preventing the deterioration of the polarizer.

From the viewpoint of improving the dispersibility of the fine particles, the amount of the alkaline component contained in the easy-adhesion composition is preferably 100 ppm or more, more preferably 300 ppm or more, still more preferably 500 ppm or more, based on the solid content of the easy-adhesion composition. On the other hand, if the content of the alkaline component is excessively large, it may be difficult to reduce the residual alkaline amount. Therefore, the amount of the alkaline component contained in the easy-adhesion composition is determined by the solid content of the easy-adhesion composition. On the other hand, 50,000 ppm or less is preferable, 10,000 ppm or less is more preferable, and 5,000 ppm or less is further preferable. The amount of the alkaline component contained in the easy-adhesion composition may be 4000 ppm or less or 3500 ppm or less with respect to the solid content of the easy-adhesion composition. As described above, specific examples of the alkaline component contained in the easy-adhesion composition include amine and ammonia, and it is preferable that the total content of these alkaline components is within the above range.

The alkaline component contained in the easy-adhesion composition may have a catalytic action or the like in addition to improving the dispersibility of the fine particles. For example, when the binder resin is a urethane-based resin, a tertiary amine such as triethylamine may be contained in the easy-adhesion composition as a urethanization catalyst for a polyurethane precursor (polypoly, isocyanate, etc.).

By applying the easy-adhesion composition on the film substrate and then heating it, the alkaline component can be volatilized and removed, and the residual alkaline component of the easy-adhesion layer 15 can be reduced. From the viewpoint of promoting volatilization of the alkaline component by heating, the alkaline component contained in the easy-adhesion composition preferably has a boiling point of 150 ° C. or lower. The boiling point of the alkaline component is more preferably 130 ° C. or lower, further preferably 120 ° C. or lower, and particularly preferably 110 ° C. or lower. The boiling point of the alkaline component may be 100 ° C. or lower or 90 ° C. or lower. When the easy-adhesion composition contains a plurality of alkaline components, the boiling point of at least one alkaline component is preferably in the above range, and the boiling points of two or more alkaline components are preferably in the above range. It is preferable that the boiling point of the alkaline component of 50% by weight or more is in the above range with respect to the total amount of alkali contained in the easy-adhesion layer. Ideally, the boiling points of all alkaline components contained in the easy-adhesion composition are in the above range. For example, when the alkaline components are amine and ammonia, the boiling point of amine is preferably within the above range.

The easy-adhesion composition may contain a cross-linking agent in addition to the binder resin (or its precursor), fine particles and alkaline components. The easy-adhesion composition includes catalysts such as cross-linking accelerators, antioxidants, ultraviolet absorbers, leveling agents, blocking inhibitors, antistatic agents, dispersion stabilizers, defoamers, thickeners, dispersants, and surfactants. , Additives such as lubricants may be included.

(Formation of easy-adhesion layer on film substrate)
The surface treatment of the film substrate may be performed before the easy-adhesion composition is applied onto the film substrate 11. By performing the surface treatment, the wetting tension of the film base material can be adjusted and the adhesion to the easy-adhesion layer 15 can be improved. Examples of the surface treatment include corona treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, chemical treatment and the like. Among these, corona treatment or plasma treatment is preferable.

Examples of the method for applying the easy-adhesion composition include a bar coating method, a roll coating method, a gravure coating method, a rod coating method, a slot orifice coating method, a curtain coating method, and a fountain coating method. The easy-adhesion layer 15 is formed by heating the easy-adhesion composition after coating to remove the solvent. The precursor of the binder resin may be reacted and cured by heating. For example, when the easy-adhesion composition contains a cross-linking agent, the cross-linking reaction can be promoted by heating.

The heating temperature at the time of forming the easy-adhesion layer is, for example, about 50 to 200 ° C. The heating temperature is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, from the viewpoint of accelerating the curing reaction of the resin component in the easy-adhesion composition and efficiently volatilizing and removing the alkaline component contained in the easy-adhesion composition. 130 ° C. or higher is more preferable, and 135 ° C. or higher is particularly preferable. Further, the heating temperature is preferably higher than the boiling point of the alkaline component contained in the easy-adhesion composition.

The heating temperature at the time of forming the easy-adhesion layer is preferably higher than the glass transition temperature (Tg) of the film substrate. By heating at a high temperature, the curing reaction of the resin component in the easy-adhesion composition can be promoted, and the alkaline component contained in the easy-adhesion composition can be efficiently volatilized and removed. The heating temperature is preferably a temperature higher than Tg of the film substrate by 10 ° C. or more.

By heating at a temperature higher than Tg of the film base material, the efficiency of volatilization and removal of alkali in the easy-adhesion composition is enhanced, and the easy-adhesion composition easily permeates the surface of the film base material, so that the film base material 11 It is considered that the adhesion between the film and the easy-adhesion layer 15 is improved. From the viewpoint of improving the adhesion of the easy-adhesion layer, the heating temperature is preferably Tg + 10 ° C. or higher, more preferably Tg + 15 ° C. or higher, and even more preferably Tg + 20 ° C. or higher for the film substrate.

When the film substrate is heated at a temperature of Tg + 10 ° C. or higher, the film substrate changes from a glass state to a rubber state and the surface is easily deformed. Therefore, at the interface between the film substrate 11 and the easy-adhesion layer 15, the resin of the film substrate An interface layer in which the components and the constituent components of the easy-adhesion layer are mixed is likely to be formed. By forming the interface layer, the adhesion between the film base material 11 and the easy-adhesion layer 15 tends to be improved.

In particular, when the surface of the film base material 11 has a region in which the fine particles of the easy-adhesion layer 15 are embedded and embedded, an easy-adhesion film having high adhesion between the film base material 11 and the easy-adhesion layer 15 can be obtained. When the fine particles are embedded in the film substrate in a rubber state in which the film substrate is heated to a temperature higher than Tg, and then the film substrate returns to the glass state, the fine particles embedded in the surface of the film substrate and their surroundings are present. It is considered that the binder resin adheres to the surface of the film base material, so that the adhesion between the film base material 11 and the easy-adhesion layer 15 is improved.

An easy-adhesion layer may be formed in the process of manufacturing the film substrate. Further, the easy-adhesion layer may be formed by utilizing the heating at the time of forming the film base material. For example, when the film base material is a stretched film, the easy-adhesion composition is applied to the surface of the film before stretching or the film after longitudinal stretching, and heating during lateral stretching or simultaneous biaxial stretching by a tenter is used. Then, the solvent can be dried and the resin can be cured.

When the film base material is stretched after the easy-adhesion composition is applied, the draw ratio is preferably 5 times or less, more preferably 4 times or less, from the viewpoint of suppressing defects such as cracks in the easy-adhesion layer. It is more preferably times or less, and particularly preferably 2.5 times or less. The lower limit of the draw ratio is not particularly limited, but from the viewpoint of improving the film strength, the draw ratio is preferably 1.3 times or more, more preferably 1.5 times or more. When the film base material is an acrylic film, it is preferable to perform stretching at the above stretching ratios in each of the transport direction (MD) and the width direction (TD) from the viewpoint of improving the film strength.

When biaxial stretching of the film base material is performed, the biaxial stretching may be sequential biaxial stretching or simultaneous biaxial stretching. Moreover, you may perform diagonal stretching. In the case of sequential biaxial stretching, as described above, the film is stretched in one direction (MD) by roll stretching, then the easy-adhesion composition is applied onto the film, and the easy-adhesion composition is heated during stretching with a tenter. May be done.

As described above, the stretching temperature of the easy-adhesion layer is preferably higher than Tg of the film substrate, preferably Tg + 10 ° C. or higher, more preferably Tg + 15 ° C. or higher, and even more preferably Tg + 20 ° C. or higher. In particular, it is preferable to apply the easy-adhesion composition and then stretch it in at least one direction at the above temperature. When stretching is performed in a rubber state at a temperature higher than Tg of the film base material, a region in which fine particles in the easy-adhesion composition are embedded is likely to be formed on the surface of the film base material, and the film base material 11 and the easy-adhesion layer 15 are formed. Adhesion tends to improve. The reason why fine particles are easily embedded in the film base material by stretching at a high temperature is that when the film base material is stretched in a rubber state, the easy-adhesive composition easily wets and spreads when the film base material is deformed, and the surface irregularities formed at the time of deformation are formed. It can be mentioned that fine particles are likely to be fitted in the concave portion. Further, when cooling is performed while releasing stress after stretching, when the film base material shrinks, the particles fitted on the surface of the film base material are fixed, so that a region in which the fine particles are embedded is formed in the film base material. It is considered easy.

The thickness of the easy-adhesion layer 15 can be adjusted by adjusting the solid content concentration and the coating thickness of the easy-adhesion composition. When the film base material is stretched after the easy-adhesion composition is applied, the thickness of the easy-adhesion layer 15 can be adjusted by the stretching ratio.

The thickness of the easy-adhesion layer 15 is not particularly limited, but is preferably 260 nm or less, more preferably 250 nm or less, from the viewpoint of promoting the removal of the alkaline component by heating. The thickness of the easy-adhesion layer may be 240 nm or less, 230 nm or less, or 220 nm or less. When the easy-adhesion film 1 is used as a polarizer protective film, the smaller the thickness of the easy-adhesion layer 15, the better the humidification durability of the polarizing plate, and the less the occurrence of optical defects such as streaky unevenness tends to occur. There is. Further, the smaller the thickness of the easy-adhesion layer 15, the more the decrease in the degree of polarization tends to be suppressed when the polarizing plate is exposed to a humidified environment.

If the alkaline component is excessively removed during the heating and drying of the easy-adhesion composition, the dispersibility of the fine particles in the binder resin is lowered, and the fine particles are aggregated and the fine particles from the surface of the easy-adhesion layer are accompanied by this. Is likely to fall off. When the fine particles agglomerate or fall off, the slipperiness of the easy-adhesive film decreases, and damage during transportation and blocking during winding are likely to occur. In addition, the fallen particles may contaminate the process, and the particles adhering to the transport roll may cause scratches or dents. Therefore, the thickness of the easy-adhesion layer 15 is preferably 100 nm or more. Further, the thicker the easy-adhesion layer, the better the adhesiveness with a film such as a polarizer, glass, or the like. From the viewpoint of improving the adhesiveness, the thickness of the easy-adhesion layer 15 is preferably 120 nm or more. The thickness of the easy-adhesion layer may be 130 nm or more, 140 nm or more, 150 nm or more, or 160 nm or more.

[Polarizer]
The polarizing plate may be provided with a transparent protective film on only one surface of the polarizing element, or may be provided with a transparent protective film on both sides of the polarizing element 5 as shown in FIG. By laminating the above-mentioned easy-adhesive film as a polarizer protective film on one surface of the polarizer, a polarizing plate having a transparent protective film on only one surface of the polarizer is formed. A polarizing plate having a polarizing element protective film on both surfaces of the polarizing element may have the above-mentioned easy-adhesive film bonded to at least one surface of the polarizing element. The polarizing plate may be one in which the above-mentioned easy-adhesion film is bonded to both sides of the polarizing element. The polarizer 5 and the easy-adhesive film 1 are bonded to each other via the adhesive layer 6.

<Polarizer>
The polarizing element 5 is polyvinyl alcohol (PVA) in which a dichroic substance such as iodine or a dichroic dye is adsorbed on a polyvinyl alcohol-based film such as polyvinyl alcohol or partially formalized polyvinyl alcohol and oriented in one direction. A system polarizer is used. For example, a PVA-based polarizer can be obtained by subjecting a polyvinyl alcohol-based film to iodine dyeing and stretching.

In the manufacturing process of the polarizer 5, treatments such as washing with water, swelling, and crosslinking may be performed, if necessary. Stretching may be performed before or after iodine dyeing, or may be performed while dyeing. The stretching may be either stretching in the air (dry stretching) or stretching in water or an aqueous solution containing boric acid, potassium iodide and the like (wet stretching), and these may be used in combination. The film thickness of the polarizer 5 is not particularly limited, but is generally about 1 to 50 μm.

As the polarizer 5, a thin PVA-based polarizer having a thickness of 10 μm or less can also be used. Examples of the thin polarizing element are described in JP-A-51-069644, JP-A-2000-338329, WO2010 / 100917 Pamphlet, Patent No. 46910205, Patent No. 4751481 and the like. Examples of thin polarizers are available. These thin polarizers are obtained by a production method including a step of stretching a PVA-based resin layer and a drawing resin base material in a laminated state, and a step of iodine dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the resin base material for stretching.

<Adhesive>
The material of the adhesive layer 6 used for bonding the polarizer 5 and the easy-adhesion film 1 is not particularly limited as long as it is optically transparent, and is an epoxy resin, a silicone resin, an acrylic resin, or a polyurethane. , Polyamide, polyether, polyvinyl alcohol and the like. The thickness of the adhesive layer 6 is, for example, about 0.01 to 20 μm, and is appropriately set according to the type of adherend, the material of the adhesive, and the like. When a curable adhesive that exhibits adhesiveness by a cross-linking reaction after coating is used, the thickness of the adhesive layer 6 is preferably 0.01 to 5 μm, more preferably 0.03 to 3 μm.

As the adhesive, various forms such as a water-based adhesive, a solvent-based adhesive, a hot melt adhesive, and an active energy ray-curable adhesive are used. Among these, a water-based adhesive or an active energy ray-curable adhesive is preferable because the thickness of the adhesive layer can be reduced.

Examples of the polymer component of the water-based adhesive include vinyl polymer, gelatin, vinyl latex, polyurethane, polyester, epoxy and the like. Among these, a vinyl polymer is preferable, and a polyvinyl alcohol-based resin is particularly preferable, because the adhesiveness between the easy-adhesive film and the polarizer is excellent. Among the polyvinyl alcohol-based resins, an acetacetyl group-containing polyvinyl alcohol is preferable.

The average degree of polymerization of the polyvinyl alcohol-based resin is preferably about 100 to 5000, more preferably 1000 to 4000, from the viewpoint of adhesiveness. The average degree of saponification of the polyvinyl alcohol-based resin is preferably 85 mol% or more, more preferably 90 mol% or more.

The aqueous adhesive composition (solution) may contain a cross-linking agent in addition to a polymer such as a polyvinyl alcohol-based resin. As the cross-linking agent, a compound having at least two functional groups in one molecule having reactivity with the polymer constituting the adhesive is used. Examples of the cross-linking agent for the polyvinyl alcohol-based resin include alkylenediamines; isocyanates; epoxies; aldehydes; amino-formaldehydes such as methylol urea and methylol melamine. Among these, amino-formaldehyde is preferable. As the amino-formaldehyde resin, a compound having a methylol group is preferable, and methylol melamine is particularly preferable. The blending amount of the cross-linking agent in the adhesive composition is preferably about 10 to 60 parts by weight, more preferably 20 to 50 parts by weight, based on 100 parts by weight of the polyvinyl alcohol-based resin.

The active energy ray-curable adhesive is an adhesive capable of radical polymerization, cationic polymerization or anionic polymerization by irradiation with active energy rays such as electron beam and ultraviolet rays. Among them, a photoradical polymerizable adhesive, a photocationic polymerizable adhesive, or a hybrid type adhesive in which photocationic polymerization and photoradical polymerization are used in combination is preferable because it can be cured with low energy. ..

Examples of the monomer of the radically polymerizable adhesive include a compound having a (meth) acryloyl group and a compound having a vinyl group. Of these, compounds having a (meth) acryloyl group are preferable. Compounds having a (meth) acryloyl group include _{alkyl (meth) acrylates such as C 1-20} chain alkyl (meth) acrylate, alicyclic alkyl (meth) acrylate, and polycyclic alkyl (meth) acrylate; hydroxyl group. Containing (meth) acrylate; Examples thereof include epoxy group-containing (meth) acrylate such as glycidyl (meth) acrylate. Radical-polymerizable adhesives include hydroxyethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, (meth) acrylamide, and (meth) acryloylmorpholin. It may contain a nitrogen-containing monomer such as. The radically polymerizable adhesive contains tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecanedimethanol diacrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, and EO-modified diacrylate as cross-linking components. It may contain a polyfunctional monomer such as glycerin tetraacrylate.

Examples of the curable component of the cationically polymerizable adhesive include compounds having an epoxy group or an oxetanyl group. 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 generally known curable epoxy compounds are used. Preferred epoxy compounds include a compound having at least two epoxy groups and at least one aromatic ring in the molecule (aromatic epoxy compound), and at least one of them having at least two epoxy groups in the molecule. Examples thereof include a compound formed between two adjacent carbon atoms constituting an alicyclic ring (alicyclic epoxy compound). A hybrid adhesive can also be obtained by including a radically polymerizable compound such as a compound having a (meth) acryloyl group in the cationically polymerizable adhesive.

The photocurable adhesive preferably contains a photopolymerization initiator. The photopolymerization initiator may be appropriately selected depending on the reaction species. For example, it is preferable to add a photoradical generator that generates radicals by light irradiation to the radically polymerizable adhesive as a photopolymerization initiator. The cationically polymerizable adhesive is preferably blended with a photocationic polymerization initiator (photoacid generator) that generates a cationic species or Lewis acid by light irradiation as a photopolymerization initiator. It is preferable to add a photocationic polymerization initiator and a photoradical generator to the hybrid adhesive.

The content of the polymerization initiator is usually about 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the monomer. When the radically polymerizable adhesive is used as an electron beam curable type, a photopolymerization initiator is not particularly required. A photosensitizer can be added to the active energy ray-curable adhesive, if necessary, in order to increase the curing rate and sensitivity. The amount of the photosensitizer used is usually about 0.001 to 10 parts by weight, preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the monomer.

The adhesive may contain appropriate additives, if necessary. Examples of additives include silane coupling agents, coupling agents such as titanium coupling agents, adhesion promoters such as ethylene oxide, ultraviolet absorbers, deterioration inhibitors, dyes, processing aids, ion trap agents, and antioxidants. , Adhesive-imparting agent, filler, plasticizer, leveling agent, foaming inhibitor, antistatic agent, heat-resistant stabilizer, hydrolysis-resistant stabilizer and the like.

[Preparation of polarizing plate]
A polarizing plate is manufactured by adhering an easy-adhesion film 1 to one surface (first main surface) of the polarizer 5 via an adhesive layer 6. In the easy-adhesive film 1, the easy-adhesive layer forming surface may be bonded to the polarizer 5 via the adhesive layer, and the non-adhesive layer non-forming surface may be bonded to the polarizer 5 via the adhesive layer. May be. As shown in FIG. 2, by adhering the polarizer 5 to the easy-adhesive layer 15 forming surface of the easy-adhesive film 1 via the adhesive layer 6, the polarizer and the polarizer protective film (easy-adhesive film 1) are attached to each other. A polarizing plate having high adhesiveness and excellent mechanical strength and durability can be obtained. When the non-formed surface of the easy-adhesive layer is bonded to the polarizer 5 via the adhesive layer, the adhesiveness to other films, adhesive layers, glass substrates, etc. provided on the easy-adhesive film can be improved. ..

In the bonding of the polarizer 5 and the easy-adhesive film 1, after applying the adhesive composition to either or both of the polarizer 5 and the easy-adhesive film 1, the polarizer 5 and the easy-adhesive film 1 are attached. It is preferable to cure the adhesive by laminating with a roll laminator or the like. Examples of the method for applying the adhesive composition to the polarizer 5 and / or the easy-adhesive film 1 include a roll method, a spray method, and a dipping method. Before applying the adhesive composition to the surface of the polarizer 5 and / or the easy-adhesive film 1, surface treatment such as corona treatment, plasma treatment, or saponification treatment may be performed.

The adhesive layer 6 is formed by bonding the polarizer 5 and the easy-adhesive film 1 and then curing the adhesive according to the type of the adhesive. When a water-based adhesive is used, the adhesive is cured by heating and drying. When an active energy ray-curable adhesive is used, the adhesive is cured by irradiation with an active energy ray such as an electron beam or ultraviolet rays.

<Transparent protective film>
The transparent protective film 2 may be attached to the second main surface of the polarizer 5 via the adhesive layer 7. As the transparent protective film 2, any suitable transparent film can be adopted. The thickness of the transparent protective film 2 is about 5 to 200 μm. From the viewpoint of mechanical strength, transparency, handleability, etc., the thickness of the transparent protective film 2 is preferably 10 to 100 μm, more preferably 15 to 60 μm. The thicknesses of the easy-adhesion film 1 and the transparent protective film 2 may be the same or different.

Materials for forming the transparent protective film 2 include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose; polystyrene and acrylonitrile. -Styrene-based polymers such as styrene copolymers; cyclic polyolefins such as polynorbornene; polycarbonate and the like can be mentioned.

The transparent protective film 2 may be provided with an easy-adhesion layer (not shown) on the surface to be bonded to the polarizer 5. The transparent protective film 2 may be provided with an easy-adhesion layer similar to the easy-adhesion layer 15 of the easy-adhesion film 1.

The adhesive layer 7 used for bonding the polarizer 5 and the transparent protective film 2 has various forms such as a water-based adhesive, a solvent-based adhesive, a hot melt adhesive, and an active energy ray-curable adhesive. Is used. The same adhesive composition may be used for the adhesive layer 6 and the adhesive layer 7.

[Use of polarizing plate]
The polarizing plate may be provided with an adhesive layer for bonding to a liquid crystal cell, an organic EL cell, or the like. As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer, those using a polymer such as acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as a base polymer are appropriately selected and used. Can be done. In particular, an acrylic pressure-sensitive adhesive is preferable because it is excellent in optical transparency, exhibits appropriate wettability and cohesiveness, and is excellent in weather resistance, heat resistance, and the like.

The pressure-sensitive adhesive layer can be attached to the polarizing plate by an appropriate method. For example, a method in which a pressure-sensitive adhesive solution having a solid content concentration of about 10 to 40% by weight in which a base polymer or the like is dissolved or dispersed in a solvent such as toluene or ethyl acetate is prepared and attached onto a polarizing plate, or on an appropriate substrate. Examples thereof include a method of transferring the pressure-sensitive adhesive layer formed in the above onto a polarizing plate.

Adhesive layers may be provided on both sides of the polarizing plate. When the pressure-sensitive adhesive layers are provided on both sides of the polarizing plate, the composition and thickness of the pressure-sensitive adhesive layers on the front and back sides may be the same or different. The thickness of the pressure-sensitive adhesive layer is generally about 5 to 500 μm.

A separator may be temporarily attached to the surface of the pressure-sensitive adhesive layer for the purpose of preventing contamination of the pressure-sensitive adhesive layer. As the separator, one in which the surface of a plastic film is coated with a release agent such as a silicone-based release agent, a long-chain alkyl-based release agent, or a fluorine-based release agent is preferably used.

The polarizing plate may be a laminated polarizing plate laminated with another optical layer. Examples of the optical layer include a retardation plate, a viewing angle compensation film, and a brightness improving film.

An image display device can be formed by attaching a polarizing plate to the surface of an image display cell such as a liquid crystal cell or an organic EL cell. The liquid crystal display device is formed by appropriately assembling a liquid crystal cell, a polarizing plate, and, if necessary, components such as a lighting system, and incorporating a drive circuit. In an organic EL display device, a metal electrode or the like is formed by adhering a circular polarizing plate in which the polarizing plate of the present invention and a retardation film (typically a 1/4 wave plate) are attached to the surface of an organic EL cell. It is possible to improve the visibility by reducing the re-emission of the reflected light of the external light due to.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The description of "%" below is% by weight unless otherwise specified.

[Preparation of easy-adhesion composition]
<Easy Adhesive Composition A>
20.6 parts by weight of water-based polyurethane (“Superflex 210R” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) containing polyester urethane and isophorone diisocyanate as resin components, and further containing triethylamine as a curing catalyst and methyl ethyl ketone as a dispersion medium, with a solid content of 34%. 5.2 parts by weight of an oxazoline-containing polymer aqueous solution having a solid content of 25% (“Epocross WS-700” manufactured by Nippon Catalyst Co., Ltd.), 7.5 parts by weight of a 20% aqueous dispersion of colloidal silica having an average primary particle size of 35 nm, and 1% by weight. The easy-adhesion composition A was prepared by mixing 3.0 parts by weight of aqueous ammonia and 63.7 parts by weight of pure water. This easy-adhesive composition contains polyurethane and an oxazoline group-containing polymer (crosslinking agent) as a resin content in a weight ratio of 84.3: 15.7, and has a solid content (total of resin content and particles) of 100 parts by weight. On the other hand, it was an aqueous solution having a concentration of 10% containing 15.3 parts by weight of silica particles, and the ammonia concentration in the aqueous solution was 300 ppm (3000 ppm with respect to the solid content).

<Easy Adhesive Compositions B to G>
The type (particle size) and blending amount of the silica fine particles and the blending amount of the resin content (aqueous polyurethane resin and oxazoline-containing polymer as a cross-linking agent) were changed as shown in Table 1 to create an easy-adhesion composition having a concentration of 10%. The thing was prepared. In each composition, the amount of ammonia water added was adjusted so that the ammonia concentration in the solution was 300 ppm. The details of the silica particles are as follows.
PL-3: 20% aqueous dispersion of spherical silica with an average primary particle size of 35 nm (Fuso Chemical Industries, Ltd. "Quatron PL-3")
KE-W10: 15% aqueous dispersion of spherical silica with an average primary particle size of 110 nm (Nippon Shokubai "Sea Horse Star KE-W10")
Technochemical: Spherical silica particles with an average primary particle diameter of 150 nm (Technochemical "Silica Microsphere Plain 24320-15")
KE-W30: 20% aqueous dispersion of spherical silica with an average primary particle size of 280 nm (Nippon Shokubai "Sea Horster KE-W30")

Table 1 shows the compositions of the easy-adhesion compositions A to G (the content of each component with respect to 100 parts by weight of the total solid content and the concentration of ammonia in the composition (aqueous solution)).

[Making an easy-to-adhere film]
<Example 1>
An easy-adhesion film was produced using a film manufacturing apparatus equipped with a melt extrusion film forming apparatus, a gravure coater, a tenter type simultaneous biaxial stretching apparatus, and a winding apparatus. As the acrylic resin, pellets of the same imidized MS resin (glass transition temperature: 120 ° C.) as those used for producing the “transparent protective film 1A” described in Examples of Japanese Patent Application Laid-Open No. 2017-26939 were used. Acrylic resin is melt-extruded from a T-die to form a film with a thickness of 160 μm, and the above-mentioned easy-adhesive composition C is applied to one surface of the film with a gravure coater to a wet thickness of about 9 μm, and heated at a temperature of 140 ° C. Easy-adhesion with a 200 nm-thick easy-adhesive layer on one surface of an acrylic film with a thickness of 40 μm, which is stretched twice in the longitudinal direction (MD) and width direction (TD) by a simultaneous biaxial stretching tenter in the furnace. I got a film.

<Examples 2 to 13 and Comparative Examples 1 to 5>
An easy-adhesive film was obtained in the same manner as in Example 1 except that the type of easy-adhesive composition, the coating thickness and the stretching temperature were changed as shown in Table 3. The thickness of the easy-adhesion layer (after stretching) was as shown in Table 3.

<Comparative Example 6>
The acrylic resin was melt-extruded and simultaneously biaxially stretched in the same manner as in Example 1 except that the easy-adhesion composition was not applied to obtain an acrylic film having a thickness of 40 μm. The above-mentioned easy-adhesion composition D is applied to one surface of an acrylic film with a wet thickness of about 2 μm and dried at 140 ° C. for 30 seconds to form an easy-adhesion layer having a thickness of 200 nm on one surface of the acrylic film. The formed easy-adhesive film was obtained.

[Evaluation of easy-adhesive film]
The following evaluation was carried out on the easy-adhesion film produced above.

<Amount of residual alkali in the easy-adhesion layer>
The amount of triethylamine and ammonia remaining in the easy-adhesion layer was quantified. The residual amount of triethylamine was quantified by gas chromatography-mass spectrometry (GC / MS) method of the solution by weighing the powder obtained by scraping the easy-adhesion layer from the surface of the easy-adhesion film and dissolving it in methanol. The residual amount of ammonia was determined by immersing the easy-adhesion film in pure water at 25 ° C., heat-extracting it with a dryer at 120 ° C. for 60 minutes, and quantifying the ammonia eluted in water by ion chromatography. The sum of the amount of triethylamine and the amount of ammonia was taken as the residual alkali amount.

<Presence / absence of interface layer>
The cross section of the easy-adhesive film is observed with a transmission electron microscope (TEM), and at the interface between the acrylic film and the easy-adhesive layer, the region (interface layer) in which the particles in the easy-adhesive layer are embedded in the acrylic film. The presence was confirmed.

<Particle dispersibility>
The surface of the easy-adhesion film was visually observed, and the presence or absence of local turbidity (increased haze) due to aggregation of silica particles was evaluated according to the following criteria.
〇: No aggregation of silica particles and good in-plane uniformity Δ: Slight turbidity due to aggregation of silica particles was confirmed ×: Turbidity due to aggregation of silica particles was clearly confirmed

<Particle fixation>
The surface of the easy-adhesive film was visually observed, and the fixability of the particles was determined based on the following criteria based on the presence or absence of scratches and dents during roll transport due to the fallen particles. 〇: Scratches caused by the particles And no dents ×: Scratches and / or dents due to the dropped particles

<Haze of easy-adhesive film>
The haze of the easy-adhesion film was measured using a haze meter (“HM-150” manufactured by Murakami Color Technology Research Institute), and less than 1.5% was set as “〇” and 1.5% or more was set as “x”.

<Blocking resistance>
After the easy-adhesive film was wound into a roll, the film was unwound from the roll and the presence or absence of wrinkles due to blocking was evaluated. After being wound on a roll and stored at room temperature for 72 hours, the film was unwound from the roll again to evaluate the presence or absence of wrinkles due to blocking.
〇: No wrinkles were found when unwound from the roll immediately after winding or when unwound from the roll after storage for 72 hours. Δ: Wrinkles when unwound from the roll immediately after winding Was not confirmed, but wrinkles were confirmed when it was unwound from the roll after storage for 72 hours. ×: When it was unwound from the roll immediately after winding, or when it was unwound from the roll after storage for 72 hours. Wrinkles were also confirmed in

<Adhesion of easy adhesive layer>
Adhesive tape (“No. 31B” manufactured by Nitto Denko) was crimped onto the surface of the easy-adhesive film on which the easy-adhesive layer was formed at a linear pressure of 8 kg / m and a crimping speed of 0.3 m / min. The tip of the adhesive tape was gripped and a 180 ° peel test was performed at a tensile speed of 30 m / min, and the adhesion of the easy-adhesive layer was determined according to the following criteria.
〇: The easy-adhesive layer did not peel off from the acrylic film and peeled off at the interface between the adhesive tape and the easy-adhesive layer. ×: The easy-adhesive layer peeled off at the interface between the acrylic film and the easy-adhesive layer.

[Preparation of polarizing plate]
(Making a polarizer)
Table 2 shows a long roll of a polyvinyl alcohol (PVA) -based resin film (“PE4500” manufactured by Kuraray) having a thickness of 45 μm, which is uniaxially stretched in the longitudinal direction so as to be 5.9 times in the longitudinal direction by a roll stretching machine. The swelling bath, the dyeing bath, the cross-linking bath 1, the cross-linking bath 2, and the washing bath shown above were conveyed in this order and dried at 70 ° C. for 5 minutes to prepare a polarizer having a thickness of 18 μm. The iodine concentration and potassium iodide concentration in the dyeing bath were adjusted so that the single transmittance of the polarizer was 43.4%.

(Preparation of UV curable adhesive)
It contains 40 parts by weight of N-hydroxyethylacrylamide and 60 parts by weight of acryloylmorpholin as curable components, and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one (BASF) as a polymerization initiator. Manufactured by "Irgacure 819") An ultraviolet curable adhesive containing 3 parts by weight was prepared.

(Attachment of polarizer and polarizer protective film)
The easy-adhesive film of each example and comparative example is used as the polarizing element protective film on one side, and the biaxially stretched cyclic polyolefin film (“Zeonoa film ZF-14” manufactured by Nippon Zeon) is used as the polarizer protective film on the other side. There was. The above-mentioned ultraviolet curable adhesive is applied to the surface of the easy-adhesive film on which the easy-adhesive layer is formed and the surface of the Zeonoa film to a thickness of about 1 μm, and after being bonded to a polarizer with a roll laminator, the integrated light intensity is 1000 / mJ / cm. ^The adhesive was cured by irradiating the ultraviolet rays of No. 2 to obtain a polarizing plate having an acrylic film (easy-adhesive film) on one surface of the polarizing element and a Zeonoa film on the other surface.

[Evaluation of polarizing plate]
The following evaluation was carried out on the easy-adhesion film produced above.

<Measurement of adhesive strength>
Cut out the polarizing plate to a size of 200 mm parallel to the stretching direction of the polarizer (absorption axis direction) and 20 mm in the orthogonal direction (transmission axis direction), and make a cut with a cutter knife between the easy-adhesion film and the polarizer. , The polarizing plate was attached to the glass plate. A peeling test was carried out with a tensile compression tester (“TG-1kN” manufactured by Minebea) at a peeling angle of 90 ° and a peeling speed of 1000 mm / min, and the adhesive strength was measured. If the adhesive strength is 2.4N / 20mm or more, it is "○", if the adhesive strength is 1.6N / 20mm or more and less than 2.4N / 20mm, it is "△", and the adhesive strength is 1.6N / 20mm. Those that were less than were marked with "x".

<Humidification durability of polarizing plate>
The polarizing plate was cut out to a size of 320 mm × 240 mm, and the surface on the cyclic polyolefin film side was bonded onto the glass via an acrylic pressure-sensitive adhesive having a thickness of 20 μm. This sample was held in a constant temperature and humidity chamber at a temperature of 60 ° C. and a relative humidity of 90% for 500 hours to carry out a heating / humidification durability test. Another polarizing plate is placed on the polarizing plate after the durability test with cross Nicol, and visually observed to confirm the presence or absence of streak-like unevenness and the uniformity of the entire surface (presence or absence of surface-like unevenness). It was evaluated according to the following criteria.

(Sujimura)
〇: No streak-like unevenness was observed Δ: Slight streak-like unevenness was visually recognized ×: Streak-like unevenness was clearly visible

(Surface unevenness)
〇: In-plane is uniform and no unevenness is confirmed Δ: In-plane slight unevenness ×: In-plane unevenness

Preparation conditions for the easy-adhesive film of Examples and Comparative Examples (type of easy-adhesive composition, timing of stretching (whether stretching was performed before or after application of the easy-adhesive composition), stretching temperature, thickness of easy-adhesive layer) , Evaluation result of easy-adhesion film (residual amount of alkali, presence / absence of interface layer, dispersibility and fixability of particles, haze, blocking resistance, adhesion), and evaluation result of polarizing plate (adhesion of polarizer and easy-adhesion film) The force and the presence or absence of unevenness after the durability test) are shown in Table 3.

In Comparative Examples 1 to 3 in which the thickness of the easy-adhesion layer was 300 nm, streak-like unevenness was confirmed after the durability test of the polarizing plate. In Comparative Example 6 in which the easy-adhesion composition was applied to the stretched film to form an easy-adhesion layer, the amount of residual alkali was large, and the adhesive force between the easy-adhesion film and the polarizer was insufficient. Further, in Comparative Example 6, in addition to the streak-like unevenness being observed in the polarizing plate after the durability test, the unevenness was generated in the entire in-plane. It is considered that the decrease in the adhesive strength and the unevenness after the durability test in Comparative Example 6 are both caused by the residual alkaline component in the easy-adhesive layer.

In Comparative Example 4 in which particles having a particle size equivalent to the thickness of the easy-adhesion layer were used, dents having the same pitch as the peripheral length of the transport roll were confirmed on the easy-adhesion film. It is considered that this is due to process contamination by the fallen fine particles. In Comparative Example 5 using particles having a particle size larger than the thickness of the easy-adhesion layer, pitch dents were confirmed as in Comparative Example 4.

In Example 13 and Comparative Example 4 in which the thickness of the easy-adhesion layer was 150 nm, the adhesive force between the polarizer and the easy-adhesion film was smaller than in other examples. From these results, it can be seen that the larger the thickness of the easy-adhesion layer, the higher the adhesive strength tends to be.

None of the easy-adhesion films of Examples 1 to 12 showed a poor appearance due to falling off of particles. In addition, no unevenness was confirmed on the polarizing plate after the durability test, and the polarizing plate had a good appearance.

In Example 9 in which the easy-adhesion layer containing 5% by weight of particles having an average particle diameter of 35 nm was provided, the blocking resistance was lower than in other examples. On the other hand, Examples 2, 3, 11 and 13 containing 5% by weight of particles having an average particle size of 150 nm and Examples 5 and 6 containing 5% by weight of particles having an average particle size of 110 nm showed excellent blocking resistance. .. In addition, Examples 7 and 8 containing 15% by weight of particles having an average particle diameter of 35 nm also showed excellent blocking resistance. From these results, it can be seen that increasing the particle size of the particles in the easy-adhesion layer and increasing the content of the particles are useful for improving the blocking resistance.

In Example 8 containing 15% of particles having an average particle diameter of 35 nm, a decrease in particle dispersibility was observed. It is considered that this is because particles having a small particle size have low dispersibility and tend to aggregate as the content increases. In Example 7 in which the amount of residual alkali was increased by lowering the stretching temperature as compared with Example 8, the dispersibility of the particles was good. However, as described above, if the amount of residual alkali is large, there is a concern that it may cause deterioration of adhesiveness and appearance deterioration such as unevenness after the durability test. Further, it is necessary to keep the residual alkali amount at a predetermined value or more in order to secure the dispersibility of the particles, which may narrow the process window.

Examples 1 to 3 and 10 to 12 using particles having an average particle size of 150 nm, and Examples 4 to 6 using particles having an average particle size of 110 nm all have good particle dispersibility and blocking resistance. Met. From these results, it is possible to improve the blocking resistance even with a small amount of particles by using fine particles having a particle size larger than 100 nm, and the dispersibility of the particles in the easy-adhesion layer even when the amount of residual alkali is small. It can be seen that an excellent easy-adhesion film can be obtained.

1 Easy-adhesive film 11 Film base material 15 Easy-adhesive layer 2 Transparent film 5 Polarizer 6,7 Adhesive layer 100 Polarizing plate

Claims (14)

An easy-adhesive film having an easy-adhesive layer on the surface of a transparent film base material.
The easy-adhesion layer contains a binder resin and fine particles, and contains
The thickness of the easy-adhesion layer is 120 to 260 nm.
The average primary particle size of the fine particles is 0.1 to 0.9 times the thickness of the easy-adhesion layer.
An easy-adhesive film having an alkaline component content of 200 ppm or less in the easy-adhesive layer. The easy-adhesion film according to claim 1, wherein the average primary particle diameter of the fine particles is larger than 100 nm and 200 nm or less. The easy-adhesion film according to claim 1 or 2, wherein the content of the fine particles in the easy-adhesion layer is 3 to 50% by weight. The easily adhesive film according to any one of claims 1 to 3, wherein the transparent film base material is an acrylic film. The easy-adhesive film according to any one of claims 1 to 4, wherein the binder resin of the easy-adhesive layer is a urethane-based resin. The easy-adhesion film according to any one of claims 1 to 5, wherein a region in which the fine particles are embedded in the transparent film base material exists at an interface between the transparent film base material and the easy-adhesion layer. The method for producing an easily adhesive film according to any one of claims 1 to 6.
An easy-adhesion composition containing a binder resin or a precursor thereof, fine particles, an alkaline component and a solvent is applied to the surface of the transparent film base material.
A method for producing an easy-adhesive film, which comprises heating the easy-adhesion composition at a temperature higher than the glass transition temperature of the transparent film substrate by 10 ° C. or more to volatilize the solvent and the alkaline component. The method for producing an easy-adhesive film according to claim 7, wherein the easy-adhesive composition contains at least one selected from the group consisting of amines and ammonia as the alkaline component. The method for producing an easy-adhesive film according to claim 8, wherein the easy-adhesive composition contains an amine having a boiling point of 150 ° C. or lower as the alkaline component. The method for producing an easily adhesive film according to any one of claims 7 to 9, wherein the alkaline component has an action of promoting dispersion of the fine particles. The production of the easy-adhesion film according to any one of claims 7 to 10, wherein the easy-adhesion composition contains a polyurethane precursor as a precursor of the binder resin and contains a tertiary amine as the alkali component. Method. The claim that the transparent film base material coated with the easy-adhesion composition is stretched in at least one direction while heating the easy-adhesion composition at a temperature higher than the glass transition temperature of the transparent film base material by 10 ° C. or more. The method for producing an easily adhesive film according to any one of 7 to 11. A polyvinyl alcohol-based polarizer having a first main surface and a second main surface, and a transparent film bonded to the first main surface of the polarizer via an adhesive layer are provided.
A polarizing plate, wherein the transparent film is the easy-adhesion film according to any one of claims 1 to 6. An image display device having an image display cell and the polarizing plate according to claim 13.

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