KR102452987B1 - Easy adhesion film and manufacturing method thereof, polarization plate, and image display device - Google Patents

Abstract

The easily adhesive film (1) is equipped with the easily adhesive layer (15) on the surface of the transparent film base material (11). The easily adhesive layer 15 contains binder resin and inorganic fine particles with an average primary particle diameter of 10 to 100 nm. Content of the alkali component of the easily bonding layer 15 is 5-75 ppm. An easily adhesive layer can be formed by apply|coating an easily adhesive composition containing a binder resin or its precursor, an inorganic fine particle, an alkali component, and a solvent on a transparent film base material, and heating.

Description

An easily adhesive film and its manufacturing method, a polarizing plate, and an image display apparatus TECHNICAL FIELD

The present invention relates to an easily adhesive film having an easily adhesive layer on the surface of a transparent film substrate and a method for manufacturing the same. Moreover, this invention relates to the polarizing plate by which the easily adhesive film was bonded by the surface of a polarizer, and the image display apparatus provided with the said polarizing plate.

BACKGROUND ART 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. In the liquid crystal display device, a polarizing plate is disposed on the surface of the viewing side of the liquid crystal cell from the display principle thereof. In a transmissive liquid crystal display device, a polarizing plate is arrange|positioned on both surfaces of a liquid crystal cell. In the organic EL display device, a circularly polarizing plate (typically a laminate of a polarizing plate and a quarter-wavelength plate) is disposed on the surface of the viewing side to prevent external light from being reflected by a metal electrode (cathode) and visually viewed as a mirror surface. there may be cases

A polarizing plate is generally provided with a transparent film (polarizer protective film) for the purpose of protection of a polarizer, etc. on one side or both surfaces of a polarizer. As the polarizer, a polyvinyl alcohol (PVA) film in which iodine is adsorbed and molecules are orientated by stretching or the like is widely used.

As a polarizer protective film bonded to the surface of a polarizer, since it is excellent in adhesiveness with a PVA system polarizer, cellulosic films, such as a cellulose acetate, are used widely. As the transparent protective film, a film made of a resin material such as acrylic, polyester, polycarbonate or cyclic polyolefin is also used. Films made of these resin materials have low moisture permeability compared to cellulosic films, and a polarizing plate with a low moisture permeability resin film bonded to the surface of the polarizer has little change in optical properties even when exposed to a high humidity environment for a long time, and tends to have excellent durability. have.

On the other hand, a film made of a resin material such as acrylic, polyester, polycarbonate, or cyclic polyolefin tends to have low adhesiveness with a PVA-based polarizer as compared with a cellulosic film. Therefore, the method of providing an easily bonding layer on the surface of the transparent film used as a polarizer protective film, and improving adhesiveness with a polarizer is proposed.

For example, in Patent Document 1, an easily adhesive film in which an easily adhesive layer containing fine particles and a binder resin is provided on the surface of an acrylic film is excellent in adhesion with a polarizer, and blocking when winding the film in a roll shape What can be suppressed has been described. In the Example of Patent Document 1, an easily adhesive film having a urethane easily adhesive layer having an average thickness of 400 nm (thickness range 300 to 500 nm) containing 1 to 7 wt% of silica fine particles on the surface of the acrylic film was used as a polarizer protective film. An example is shown.

Japanese Patent No. 5354733

While the size of the image display device and the increase in luminance are progressing, the polarizing plate constituting the image display device is required to have a small change in optical properties even in a harsher environment (eg, higher temperature and high humidity conditions). The polarizing plate using the easily adhesive film of patent document 1 as a polarizer protective film is excellent in the adhesiveness of a polarizer and a polarizer protective film, and adhesive reliability is also high. However, when the polarizing plate using the easily adhesive film disclosed in patent document 1 as a polarizer protective film is exposed to a high humidity environment for a long time, the subject that stripe-shaped nonuniformity arises and may cause the fall of a display characteristic newly became clear.

In view of the above problems, the present invention is an easily adhesive film that has excellent adhesion to a polarizer, etc., is difficult to cause blocking, and is also difficult to produce optical defects such as stripe-shaped unevenness even when exposed to a high temperature and high humidity environment for a long time. is intended to provide

As a result of examination by the present inventors in view of the above subject, it is that alkali components such as ammonia and amine added in the easily adhesive composition for the purpose of improving the dispersibility of fine particles remain in the easily adhesive layer, the durability in a humidified environment is reduced It is one cause of , and it discovered that the said subject was solvable by making the amount of residual alkali in an easily bonding layer into a predetermined range.

The present invention relates to an easily adhesive film having an easily adhesive layer on the surface of a transparent film substrate and a method for manufacturing the same. An easily adhesive layer contains binder resin and microparticles|fine-particles. As microparticles|fine-particles, inorganic microparticles|fine-particles are preferable. The average primary particle diameter of microparticles|fine-particles is 10-100 nm, for example. As for content of the alkali component of an easily bonding layer, 5-75 ppm is preferable, and it is preferable that the sum total of content of an amine and ammonia is 5-75 ppm. As for the thickness of an easily bonding layer, 40-280 nm is preferable.

As the transparent film substrate, an acrylic film or the like is used. A urethane-type resin etc. are used as binder resin of an easily bonding layer. Content of the microparticles|fine-particles in an easily bonding layer becomes like this. Preferably it is about 8 to 50 weight%. The microparticles|fine-particles of an easily bonding layer may be embedded in the transparent film base material.

An easily adhesive layer is formed by apply|coating and heating an easily adhesive composition to the surface of a transparent film base material. The easily adhesive composition contains a binder resin or a precursor thereof, fine particles, an alkali component, and a solvent. When an alkali component is contained in an easily adhesive composition, the dispersibility of microparticles|fine-particles improves and the easily adhesive film excellent in slidability is obtained. In addition, the alkali component can also act as a catalyst for accelerating the reaction of the binder resin (precursor). As for the boiling point of an alkali component from a viewpoint of promoting volatilization of the alkali component by heating, 150 degrees C or less is preferable. As an alkali component, an amine, ammonia, etc. are mentioned.

By raising the heating temperature after application|coating of an easily bonding composition, volatilization of an alkali component can be accelerated|stimulated and an easily bonding layer with few residual alkali components can be formed. For example, you may heat an easily bonding composition to temperature 10 degreeC or more higher than the glass transition temperature of a transparent film base material. By making heating temperature high, the area|region in which the microparticles|fine-particles of the easily adhesive layer were embedded in the transparent film base material is easy to form, and there exists a tendency for the adhesiveness of a transparent film base material and an easily adhesive layer to improve.

After apply|coating an easily adhesive composition on a transparent film base material, you may extend|stretch, heating a transparent film base material. In particular, by stretching the transparent film substrate while heating the easily adhesive composition at a temperature 10° C. or more higher than the glass transition temperature of the transparent film substrate, the adhesion between the transparent film substrate and the easily adhesive layer tends to be improved.

The easily adhesive film has excellent adhesion to other films or glass substrates. An easily adhesive film can be used as a polarizer protective film, for example. For example, a polarizing plate is obtained by bonding an easily adhesive film to the surface of a polyvinyl alcohol type polarizer through an adhesive bond layer. An image display apparatus can be formed by arrange|positioning a polarizing plate on the surface of image display cells, such as a liquid crystal display cell and an organic electroluminescent cell.

The easily-adhesive film of the present invention has excellent adhesion, is unlikely to cause blocking, and is difficult to cause optical defects even when exposed to a high temperature and high humidity environment for a long time, so it is suitable as a film for display devices such as a polarizer protective film. used

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the structural example of an easily adhesive film.
It is sectional drawing which shows the structural example of a polarizing plate.
It is a cross-sectional TEM observation image of the easily adhesive film in which the interface layer is formed in the interface of a film base material and an easily adhesive layer.
It is a cross-sectional TEM observation image of the easily adhesive film in which the interface layer is not formed in the interface of a film base material and an easily adhesive layer.
5 is an orthogonal Nicole observation photograph before and after the durability test of the polarizing plate.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows the structural example of the easily adhesive film which concerns on one Embodiment of this invention. As for the easily adhesive film 1, the easily adhesive layer 15 is provided in the at least one surface of the film base material 11. An easily adhesive layer may be provided in both surfaces of a film base material. An easily adhesive film is used by bonding to another film, a glass substrate, etc.

A polarizer protective film is mentioned as a usage form of an easily adhesive film. 2 : is sectional drawing which shows the structural example of a polarizing plate provided with the easily adhesive film 1 as a polarizer protective film. The polarizing plate 100 is equipped with the easily adhesive film 1 joined to one surface (1st main surface) of the polarizer 5 through the adhesive bond layer 6 . In the polarizing plate 100 shown in FIG. 2, the easily adhesive film 1 has the easily adhesive layer 15 in the bonding surface with the polarizer 5 of the film base material 11. As shown in FIG. An easily adhesive layer may be provided in the surface to which the polarizer 5 is not bonded. In the polarizing plate 100 shown in FIG. 2, the transparent protective film 2 is bonded to the other surface (2nd main surface) of the polarizer 5 via the adhesive bond layer 7 .

[Easy Adhesive Film]

The easily adhesive film 1 is equipped with the easily adhesive layer 15 in at least one surface of the film base material 11. As shown in FIG.

<Film substrate>

As the film base material 11, a transparent film is preferable. 80 % or more is preferable, as for the total light transmittance of a transparent film base material, 85 % or more is more preferable, and 90 % or more is still more preferable. Examples of the resin material constituting the film base material 11 include acrylic resins, polyester resins, polycarbonate resins, polyolefin resins, cyclic polyolefin resins, polystyrene resins, polyamide resins, polyimide resins, and the like. have. When an easily adhesive film is used as an optically isotropic polarizer protective film, since birefringence is small, as a resin material of the film base material 11, an acrylic resin or a cyclic polyolefin resin is preferable, and an acrylic resin is especially preferable.

As cyclic polyolefin resin, polynorbornene is mentioned, for example. As a commercial item of cyclic polyolefin resin, ZEONOR and ZEONEX by Zeon Corporation, ARTON by JSR, APEL by Mitsui Chemicals Inc., TOPAS by Topas Advanced Polymers Co., Ltd., etc. are mentioned. It is preferable that a cyclic polyolefin type film contains 50 weight% or more of cyclic olefin type resin.

Examples of the acrylic resin include poly(meth)acrylic acid esters such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylic acid ester copolymer, and methyl methacrylic acid-acrylic acid ester- (meth)acrylic acid copolymer, (meth)acrylic acid methyl-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group (e.g., methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate) -(meth)acrylic acid norbornyl copolymer etc.) are mentioned.

In this specification, "(meth)acryl" means acryl and/or methacryl. 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 an acrylic resin, the acrylic resin which has a glutaric anhydride structure as described in Unexamined-Japanese-Patent No. 2006-283013, Unexamined-Japanese-Patent No. 2006-335902, Unexamined-Japanese-Patent No. 2006-274118, etc.; and/or the lock described in Japanese Patent Application Laid-Open No. 2000-230016, Japanese Patent Application Laid-Open No. 2001-151814, Japanese Patent Application Laid-Open No. 2002-120326, Japanese Patent Application Laid-Open No. 2002-254544, and Japanese Patent Application Laid-Open No. 2005-146084 You may use the acrylic resin which has a tone ring structure. Since the acrylic resin having a glutaric anhydride structure and the acrylic resin having a lactone ring structure have high heat resistance, high transparency, and high mechanical strength, they are suitable for manufacturing a polarizing plate having a high degree of polarization and excellent durability.

When the film base material 11 is an acrylic film, 50 weight% or more is preferable, as for content of the acrylic resin in a film base material, 60 to 98 weight% is more preferable, and its 70 to 97 weight% is still more preferable. The acrylic film may contain a thermoplastic resin other than the acrylic resin. For example, by mix|blending another thermoplastic resin, the birefringence of an acrylic resin is canceled and the acrylic film excellent in optical isotropy is obtained. Moreover, you may mix|blend thermoplastic resins other than an acrylic resin for the purpose of the mechanical strength improvement of a film, etc.

Examples of the thermoplastic resin other than the acrylic resin include olefinic polymers, vinyl halide polymers, polystyrene, styrene and acrylic monomers and copolymers, polyesters, polyamides, polyacetals, polycarbonates, polyphenylene oxides, polyphenylene sulfides, and polyethers. Ether ketone, polysulfone, polyether sulfone, polyoxybenzylene, polyamideimide, rubber-type polymer, etc. are mentioned.

The film base material 11 may contain additives, such as antioxidant, a stabilizer, a reinforcing material, a ultraviolet absorber, a flame retardant, an antistatic agent, a coloring agent, a filler, a plasticizer, a lubricant, and a filler. After mixing a resin material, an additive, etc. and setting it as thermoplastic resin compositions, such as a pellet, in advance, you may form into a film.

The thickness of the film base material 11 is about 5-200 micrometers. From viewpoints of mechanical strength, transparency, handling property, etc., 10-100 micrometers is preferable and, as for the thickness of the film base material 11, 15-60 micrometers is more preferable.

100 degreeC or more is preferable and, as for the glass transition temperature Tg of the film base material 11, 110 degreeC or more is more preferable. When the film substrate 11 is an acrylic film, as described above, by using an acrylic resin having a glutaric anhydride structure or an acrylic resin having a lactone ring structure as the acrylic resin, the Tg of the acrylic film is increased, and heat resistance is improved. can do it Although the upper limit of Tg of the film base material 11 is not specifically limited, From a viewpoint, such as a moldability, 170 degrees C or less is preferable.

As a manufacturing method of the film base material 11, the solution casting method, the melt extrusion method, the calendering method, the compression molding method, etc. are mentioned. The film base material 11 may be either an unstretched film or a stretched film. When the film substrate 11 is an acrylic film, from the viewpoint of improving the mechanical strength, the acrylic film is preferably a stretched film stretched in at least one direction, and particularly preferably a biaxially stretched film. By blending another thermoplastic resin so as to offset the birefringence of the acrylic resin, an acrylic film having small retardation and excellent optical isotropy even when stretched can be obtained.

<Easy Adhesive Layer>

The easily adhesive layer 15 provided on the surface of the film substrate 11 includes a binder resin and fine particles. By providing the easily bonding layer 15, the adhesiveness with respect to films, such as a polarizer, a glass substrate, etc. can be improved. When the easily adhesive layer 15 contains microparticles|fine-particles, fine unevenness|corrugation is formed in the surface of the easily adhesive layer 15, and the slidability of a film improves. Therefore, it contributes to reduction of the damage at the time of roll conveyance of the easily adhesive film 1, and blocking suppression at the time of winding up in roll shape.

(binder resin)

As the binder resin, from the viewpoint of excellent adhesion to a film substrate such as an acrylic film, a polyurethane resin, an epoxy resin, an isocyanate resin, a polyester resin, a polymer containing an amino group in the molecule, a crosslinkable functional group such as an oxazoline group A resin (polymer) having a reactive group such as an acrylic resin is used. As binder resin of the easily bonding layer 15, a polyurethane resin is especially preferable. The easily adhesive layer 15 containing a polyurethane resin binder has high adhesiveness with the film base material 11. Moreover, when the easily adhesive film 1 in which the easily adhesive layer 15 contains a polyurethane resin binder laminates|stacks films, such as a polarizer, through an adhesive bond layer, there exists a tendency to show high adhesiveness.

A urethane resin is typically a reaction product of a polyol and a polyisocyanate. As the polyol component, a polymer polyol such as polyacryl polyol, polyester polyol, and polyether polyol is preferably used.

Polyacrylic polyol is typically obtained by polymerization of (meth)acrylic acid ester and a hydroxyl group-containing monomer. As (meth)acrylic acid ester, methyl (meth)acrylate, (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid cyclohexyl etc. are mentioned, for example. As the hydroxyl group-containing monomer, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 2-hydroxybutyl, (meth)acrylic acid 4- hydroxyalkyl esters of (meth)acrylic acid such as hydroxybutyl and 2-hydroxypentyl (meth)acrylic acid; (meth)acrylic acid monoesters of polyhydric alcohols such as glycerin and trimethylolpropane; N-methylol (meth)acrylamide etc. are mentioned.

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

Polyester polyols are typically obtained by reaction of polybasic acids with polyols. Examples of the polybasic acid include orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalene dicarboxylic acid, 2,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, and tetrahydrophthalic acid. aromatic dicarboxylic acids such as; Oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkyl aliphatic dicarboxylic acids such as succinic acid, linoleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, and itaconic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; or reactive derivatives such as acid anhydrides, alkyl esters and acid halides thereof.

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, and 1,8-octane. Diol, 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-pentylene glycol , 3-methyl-1,5-pentylene glycol, 1,2-dimethylbutylene glycol, 1,3-dimethylbutylene glycol, 2,3-dimethylbutylene glycol, 1,4-dimethylbutylene glycol, di Ethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, etc. can be heard

The polyether polyol is typically obtained by ring-opening polymerization of an alkylene oxide with a polyhydric alcohol and adding it. As polyhydric alcohol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, trimethylol propane etc. are mentioned, for example. 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, and 2,4,4-trimethylhexamethylene diisocyanate. aliphatic diisocyanates such as , lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, and 3-methylpentane-1,5-diisocyanate; Isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-cyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane alicyclic diisocyanates such as; tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, aromatic diisocyanates such as 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, and 1,4-phenylene diisocyanate; and aromatic diisocyanates such as dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate and α,α,α,α-tetramethylxylylene diisocyanate.

The urethane resin constituting the easily bonding layer 15 preferably has a carboxyl group. When a urethane resin has a carboxyl group, introduction of a crosslinked structure becomes possible, and there exists a tendency for adhesive durability, such as the easily adhesive film 1 and a polarizer, to improve. The urethane resin which has a carboxyl group is obtained by adding the polyol and polyisocyanate, for example, and making the chain lengthening agent which has a free carboxyl group react. Examples of the chain lengthening agent having a free carboxyl group include dihydroxycarboxylic acid and dihydroxysuccinic acid. As dihydroxycarboxylic acid, dialkylol alkanoic acids, such as dimethylol alkanoic acid (For example, dimethylol acetic acid, dimethylol butanoic acid, dimethylol propionic acid, dimethylol butyric acid, dimethylol pentanoic acid), etc. are mentioned.

The manufacturing method of a urethane resin is not specifically limited, Any of the one-shot method in which a monomer component is reacted at once, and the multistage method in which it reacts stepwise may be sufficient. In the case of introducing a carboxyl group into the urethane resin using a chain lengthening agent having a free carboxyl group, a multi-step method is preferable. In manufacture of a urethane resin, you may use a urethane reaction catalyst as needed.

5,000-600,000 are preferable and, as for the number average molecular weight of a urethane resin, 10,000-400,000 are more preferable. 10-50 are preferable and, as for the acid value of a urethane resin, 20-45 are more preferable.

The urethane resin may have a crosslinked structure. When a crosslinked structure is introduce|transduced into a urethane resin, there exists a tendency for adhesive durability of the easily adhesive film 1 and a polarizer, etc. to improve. As the crosslinking agent, those capable of reacting with the crosslinkable functional group of the urethane resin may be used without particular limitation. When the urethane resin has a carboxyl group, a crosslinking agent containing an amino group, an oxazoline group, an epoxy group, a carbodiimide group, and the like is used. Among these, the crosslinking agent which has an oxazoline group is preferable. Since the oxazoline group has low reactivity with a carboxyl group at normal temperature, the pot life when mixed with a urethane resin is long, and it can respond flexibly to the lead time of a process.

A low molecular weight compound may be sufficient as a crosslinking agent, and a polymer may be sufficient as it. Since the solubility to an aqueous composition is high and it is excellent also in compatibility with a urethane resin, an acryl-type polymer is preferable as a crosslinking agent. In particular, when an acrylic polymer having an oxazoline group is used as the crosslinking agent, the adhesiveness between the easily adhesive film 1 and films such as a polarizer tends to improve.

1-30 weight part is preferable with respect to 100 weight part of urethane resins, and, as for the usage-amount of a crosslinking agent, 3-20 weight part is more preferable.

(fine particles)

When microparticles|fine-particles are contained in the easily adhesive layer 15, a fine uneven|corrugated shape is formed on the surface of an easily adhesive layer, the slidability of the easily adhesive film 1 improves, and blocking can be suppressed. From a viewpoint of forming the unevenness|corrugation which contributes to sliding property improvement, 10 nm or more is preferable, as for the particle diameter (average primary particle diameter) of microparticles|fine-particles, 15 nm or more are more preferable, and 20 nm or more are still more preferable. It is preferable that the average primary particle diameter of microparticles|fine-particles is smaller than the thickness of an easily adhesive layer. When the particle diameter of microparticles|fine-particles is smaller than the thickness of an easily bonding layer, drop-off|omission of the microparticles|fine-particles from an easily bonding layer can be suppressed. 250 nm or less is preferable and, as for the particle diameter of microparticles|fine-particles, 200 nm or less is more preferable. Moreover, when the average primary particle diameter of microparticles|fine-particles is smaller than a visible light wavelength, scattering of visible light at the interface of binder resin and microparticles|fine-particles can be suppressed. From a viewpoint of transparency improvement, 100 nm or less is preferable, as for the particle diameter of microparticles|fine-particles, 80 nm or less is more preferable, 60 nm or less is still more preferable, 50 nm or less is especially preferable.

The microparticles|fine-particles of the easily bonding layer 15 may be either inorganic microparticles|fine-particles and organic microparticles|fine-particles. Since it is excellent in dispersibility and the uniformity of a particle diameter, as microparticles|fine-particles, inorganic microparticles|fine-particles are preferable. 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, etc. are mentioned. Among these, inorganic oxides are preferable. In order to suppress light scattering due to the fine particles, it is preferable that the refractive index difference between the binder resin (generally about 1.5 refractive index) and the fine particles is small. Since the refractive index difference with binder resin is small and it is excellent in dispersibility, as microparticles|fine-particles of the easily bonding layer 15, a silica particle is preferable.

When forming the easily adhesive layer 15 with an aqueous composition, it is preferable to use fine particles with high water dispersibility. You may mix|blend the aqueous dispersion of microparticles|fine-particles in a composition. In order to improve the dispersibility of microparticles|fine-particles, it is preferable to add alkali components, such as an amine and ammonia, to make an easily adhesive composition weakly alkaline.

As the water-dispersible silica particles, colloidal silica is preferably used. As colloidal silica, Quartron PL series from Fuso Chemical Co., Ltd., SNOWTEX series from Nissan Chemical Industries, Ltd., AERODISP series and AEROSIL series from Nippon Aerosil Co., Ltd., Nippon Shokubai Co. You may use commercial items, such as the SEAHOSTAR KE series manufactured by Ltd.

From a viewpoint of improving the slidability of the easily adhesive film 1 by the uneven|corrugated formation to the surface of the easily adhesive layer 15, as for content of the microparticles|fine-particles in the easily adhesive layer 15, 3 weight% or more is preferable, and 5 weight% The above is more preferable. In particular, when the thickness of the easily adhesive layer 15 is 280 nm or less, by increasing the content of the particles to increase the amount (number density) of the particles per unit area, it is preferable to uniformly form irregularities in the surface of the easily adhesive layer 15, 8 weight% or more is preferable, as for content of the microparticles|fine-particles of the easily bonding layer 15, 10 weight% or more is more preferable, 12 weight% or more is still more preferable. When content of the microparticles|fine-particles of the easily adhesive layer 15 is too large, the fall of the optical characteristic resulting from the increase of the light scattering in the interface of binder resin and microparticles|fine-particles may be caused. Moreover, since the relative content of binder resin becomes small with increase in microparticles|fine-particles content, the adhesiveness of an easily bonding layer may fall. Therefore, 50 weight% or less is preferable, as for content of the microparticles|fine-particles in the easily bonding layer 15, 40 weight% or less is more preferable, and its 30 weight% or less is still more preferable.

(Residual Alkali Amount)

In order to improve the dispersibility of microparticles|fine-particles, when alkali components, such as an amine and ammonia, are used, an alkali component will inevitably remain in an easily adhesive layer. When the easily adhesive film 1 is used as a polarizer protective film, when the residual alkali component of the easily adhesive layer 15 is eluted by moisture or the like, the polarizer is deteriorated to reduce the degree of polarization of the polarizing plate, Defects may occur.

From a viewpoint of improving the humidification durability of a polarizing plate, 75 ppm or less is preferable, as for the amount of residual alkali of the easily adhesive layer 15, 70 ppm or less is more preferable, 60 ppm or less is still more preferable, 55 ppm or less is especially preferable. From a viewpoint of the improvement of the humidification durability of a polarizing plate, it is so preferable that there are few residual alkali amounts in the easily bonding layer 15.

On the other hand, when the amount of residual alkali of the easily adhesive layer 15 is excessively small, the dispersibility of microparticles|fine-particles may be impaired, and appearance defects, such as cloudiness resulting from the aggregation of microparticles|fine-particles, may arise. Moreover, due to the aggregation of microparticles|fine-particles by the fall of a dispersibility, or fall-off|omission from an easily adhesive layer, appropriate unevenness|corrugation does not form on the surface of an easily adhesive layer, and there exists a tendency for the sliding property of an easily adhesive film to fall. Therefore, 5 ppm or more is preferable, as for the amount of residual alkali of the easily bonding layer 15, 10 ppm or more is more preferable, and 20 ppm or more is still more preferable.

An amine and ammonia are mentioned as a specific example of the residual alkali component in an easily bonding layer. Therefore, it is preferable that the sum total of content of the amine in an easily bonding layer and ammonia exists in the said range. The amount of alkali in an easily adhesive layer can be quantified by liquid chromatography, ion chromatography, etc. according to the kind of alkali component. You may quantify an alkali component by the analytical method (for example, LC/MS) which combined chromatography and mass spectrometry (MS). When a some alkali component is contained in an easily bonding layer, let the sum total of each component be alkali component content (residual amount) of an easily bonding layer.

<Formation of easily adhesive layer>

The formation method of the easily bonding layer 15 to the surface of the film base material 11 is not specifically limited. Preferably, the easily adhesive layer 15 is formed by apply|coating and heating the easily adhesive composition (coating liquid) containing a binder resin and microparticles|fine-particles on the film base material 11. FIG.

(Easily Adhesive Composition)

It is preferable that the easily adhesive composition is an aqueous composition which uses water as a solvent (and the dispersion medium with respect to microparticles|fine-particles). 1 to 30 weight% is preferable, as for the density|concentration of solid content (nonvolatile component) in an easily adhesive composition, 2 to 20 weight% is more preferable, 3 to 15 weight% is still more preferable.

A water-based easily adhesive composition contains water as a solvent (and dispersion medium), a binder resin or its precursor, and microparticles|fine-particles. It is preferable that an easily adhesive composition further contains an alkali component. As described above, the alkali component has an action of promoting dispersion of the fine particles. Therefore, when an easily adhesive composition contains an alkali component, the dispersibility of microparticles|fine-particles is improved, and the easily adhesive film excellent in an external appearance and sliding property is obtained.

On the other hand, when the alkali contained in the easily adhesive composition remains in the easily adhesive layer, it may cause deterioration of the heat-and-moisture resistance of the polarizing plate. In particular, even a small amount of strong alkali such as caustic may cause deterioration of the polarizer. Therefore, as an alkali component contained in an easily bonding composition, weak alkali components, such as ammonia and an amine, are preferable. As for the pH of an easily adhesive composition (coating liquid) from a viewpoint of making the dispersibility improvement of microparticles|fine-particles improvement, and deterioration prevention of a polarizer compatible, about 7.5-9 are preferable.

From a viewpoint of improving the dispersibility of microparticles|fine-particles, 300 ppm or more is preferable with respect to solid content of an easily adhesive composition, and, as for the quantity of the alkali component contained in an easily adhesive composition, 500 ppm or more is more preferable. On the other hand, since it may become difficult to reduce the amount of residual alkali when content of an alkali component is too large, 50000 ppm or less is preferable with respect to the solid content of an easily adhesive composition, as for the quantity of the alkali component contained in an easily adhesive composition, 10000 ppm or less. is more preferable, and 5000 ppm or less is still more preferable. As mentioned above, an amine and ammonia are mentioned as a specific example of the alkali component contained in an easily bonding composition, It is preferable that the sum total of content of these alkali components exists in the said range.

In addition to improving the dispersibility of microparticles|fine-particles, the alkali component contained in an easily bonding composition may have a catalytic action etc. For example, when the binder resin is a urethane resin, the easily adhesive composition may contain a tertiary amine such as triethylamine as a catalyst for urethanization of a polyurethane precursor (polyol, isocyanate, etc.).

By heating after apply|coating an easily bonding composition on a film base material, an alkali component can be volatilized and the residual alkali component of the easily bonding layer 15 can be reduced. It is preferable that the boiling point of the alkali component contained in an easily adhesive composition from a viewpoint of promoting volatilization of the alkali component by heating is 150 degrees C or less. As for the boiling point of an alkali component, 130 degrees C or less is more preferable, 120 degrees C or less is still more preferable, and 110 degrees C or less is especially preferable. The boiling point of the alkali component may be 100°C or less or 90°C or less. When a some alkali component is contained in an easily adhesive composition, it is preferable that the boiling point of at least 1 alkali component is the said range, and it is preferable that the boiling point of two or more alkali components is the said range. It is preferable that the boiling point of 50 weight% or more of alkali components is the said range with respect to the whole quantity of alkali contained in an easily bonding layer. It is ideal that the boiling points of all the alkali components contained in an easily adhesive composition are the said range.

The easily adhesive composition may contain a crosslinking agent in addition to binder resin (or its precursor), microparticles|fine-particles, and an alkali component. The easily adhesive composition may contain additives such as catalysts such as crosslinking accelerators, antioxidants, ultraviolet absorbers, leveling agents, antiblocking agents, antistatic agents, dispersion stabilizers, defoamers, thickeners, dispersants, surfactants, and lubricants.

(Formation of an easily adhesive layer on a film base material)

Before apply|coating an easily adhesive composition on the film base material 11, you may surface-treat a film base material. By surface-treating, the wetting tension of a film base material can be adjusted and adhesiveness with the easily bonding layer 15 can be improved. Examples of the surface treatment include corona treatment, plasma treatment, ozone blowing, ultraviolet irradiation, flame treatment, and chemical treatment. Among these, corona treatment or plasma treatment is preferable.

Examples of the method for applying the easily adhesive composition include a bar coat method, a roll coat method, a gravure coat method, a rod coat method, a slot orifice coat method, a curtain coat method, and a fountain coat method. The easily adhesive layer 15 is formed by heating the easily adhesive composition after application|coating and removing a solvent. You may make it harden by making the precursor of binder resin react by heating. For example, when an easily adhesive composition contains a crosslinking agent, a crosslinking reaction can be accelerated|stimulated by heating.

The heating temperature at the time of forming an easily bonding layer is about 50-200 degreeC, for example. While promoting the hardening reaction of the resin component in an easily bonding composition, from a viewpoint of volatilizing efficiently the alkali component contained in an easily bonding composition, 100 degreeC or more is preferable and, as for heating temperature, 120 degreeC or more is more preferable and 130°C or higher is more preferred, and 135°C or higher is particularly preferred. Moreover, it is preferable that heating temperature is higher than the boiling point of the alkali component contained in an easily bonding composition.

It is preferable that the heating temperature at the time of easily bonding layer formation is higher than the glass transition temperature (Tg) of a film base material. By heating at high temperature, while promoting the hardening reaction of the resin component in an easily bonding composition, the alkali component contained in an easily bonding composition can be volatilized and removed efficiently. It is preferable that a heating temperature is a temperature 10 degreeC or more higher than Tg of a film base material.

By heating at a higher temperature than Tg of the film base material, while improving the volatilization removal efficiency of alkali in the easily adhesive composition, the easily adhesive composition permeates easily on the surface of the film base material, and the film base material 11 and the easily adhesive layer 15 It is thought that adhesiveness improves. From a viewpoint of improving the adhesiveness of an easily bonding layer, Tg+10 degreeC or more of a film base material is preferable, as for heating temperature, Tg+15 degreeC or more is more preferable, and Tg+20 degreeC or more is still more preferable.

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 thereof is easily deformed. Therefore, at the interface between the film substrate 11 and the easily adhesive layer 15, The interfacial layer in which the resin component and the structural component of the easily bonding layer were mixed is easy to form. When the interface layer is formed, there exists a tendency for the adhesiveness of the film base material 11 and the easily bonding layer 15 to improve.

In particular, as shown in the cross-sectional observation of FIG. 3 , when there is a region buried by the fine particles of the easily adhesive layer 15 being sandwiched between the surface of the film substrate 11 , the film substrate 11 and the easily adhesive layer are present. An easily adhesive film with high adhesiveness of (15) is obtained. When the film substrate is heated to a higher temperature than Tg in a rubber state, the fine particles are embedded in the film substrate, and then the film substrate returns to the glass state, the fine particles embedded in the surface of the film substrate and the binder resin present around the film substrate Since it adheres to the surface of , it is thought that the adhesiveness of the film base material 11 and the easily bonding layer 15 improves.

You may form an easily bonding layer in the manufacturing process of a film base material. Moreover, you may form an easily bonding layer using the heating at the time of formation of a film base material. For example, when the film base material is a stretched film, the easily adhesive composition is applied to the surface of the film before stretching or the film after longitudinal stretching, and the solvent is dried using heating during lateral stretching or simultaneous biaxial stretching by a tenter. or resin can be cured.

When stretching the film substrate after applying the easily adhesive composition, from the viewpoint of suppressing defects such as cracks in the easily adhesive layer, the draw ratio is preferably 5 times or less, more preferably 4 times or less, 3 Times or less are more preferable, and 2.5 times or less are particularly preferable. Although the lower limit of a draw ratio is not specifically limited, From a viewpoint of a film strength improvement, 1.3 times or more are preferable, and, as for a draw ratio, 1.5 times or more is more preferable. When the film base material is an acrylic film, from the viewpoint of improving the film strength, it is preferable to perform stretching in each of the conveying direction (MD) and the width direction (TD) at the above draw ratios.

When performing biaxial stretching of a film base material, sequential biaxial stretching may be sufficient as biaxial stretching, and simultaneous biaxial stretching may be sufficient as it. Moreover, you may perform diagonal stretch. When performing sequential biaxial stretching, the film is stretched in one direction (MD) by roll stretching as described above, then the easily adhesive composition is applied on the film, and the easily adhesive composition is heated during stretching by a tenter. may do

As above-mentioned as a heating temperature of an easily adhesive layer, it is preferable that extending|stretching temperature is higher than Tg of a film base material, Tg+10 degreeC or more is preferable, Tg+15 degreeC or more is more preferable, Tg+20 degreeC or more is more preferable. more preferably. In particular, after applying the easily adhesive composition, it is preferable to perform stretching in at least one direction at the above temperature. When stretching is performed in a rubber state at a temperature higher than the Tg of the film substrate, a region in which the fine particles in the easily adhesive composition are embedded on the surface of the film substrate is easily formed, and the adhesion between the film substrate 11 and the easily adhesive layer 15 tends to improve There is this. As the reason that the fine particles are easily embedded in the film substrate by stretching at high temperature, if stretching is performed in a rubber state, the easily adhesive composition is easily wetted and diffused during deformation of the film substrate, so The thing which tends to the state in which microparticles|fine-particles were pinched|interposed is mentioned. In addition, if cooling is performed while releasing stress after stretching, since particles intercalated on the surface of the film substrate are fixed when the film substrate contracts, it is considered that a region in which the fine particles are embedded is likely to be formed in the film substrate.

The thickness of the easily bonding layer 15 can be adjusted by adjusting the solid content concentration and application|coating thickness of an easily bonding composition. When extending|stretching a film base material after apply|coating an easily bonding composition, the thickness of the easily bonding layer 15 can be adjusted also with a draw ratio.

Although the thickness of the easily bonding layer 15 is not specifically limited, From a viewpoint of promoting the removal of the alkali component by heating, 280 nm or less is preferable, 250 nm or less is more preferable, 230 nm or less is still more preferable. When the easily adhesive film 1 is used as a polarizer protective film, the smaller the thickness of the easily adhesive layer 15, the better the humidification durability of the polarizing plate, and the occurrence of optical defects such as stripe-shaped unevenness tends to decrease. . Moreover, there exists a tendency for the fall of the polarization degree when a polarizing plate to be exposed to a humidification environment to be suppressed, so that the thickness of the easily adhesive layer 15 is small.

When an alkali component is excessively removed at the time of heat drying of an easily adhesive composition, the dispersibility of the microparticles|fine-particles in binder resin will fall, and aggregation of microparticles|fine-particles, drop-off|omission of the microparticles|fine-particles from the surface of an easily adhesive layer accompanying this, etc. are easy to generate|occur|produce. When aggregation and drop-off|omission of microparticles|fine-particles generate|occur|produce, the slidability of an easily adhesive film will fall, and it will become easy to generate|occur|produce the wound at the time of conveyance, and the blocking at the time of winding up. Therefore, 40 nm or more is preferable, as for the thickness of the easily bonding layer 15, 50 nm or more is more preferable, 80 nm or more is still more preferable, and 100 nm or more is especially preferable. 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, or 150 nm or more may be sufficient as the thickness of an easily bonding layer. It is preferable that the thickness of the easily bonding layer 15 is the said range also from a viewpoint of expressing the adhesive improvement effect by the easily bonding layer 15 appropriately.

[Polarizer]

A polarizing plate may be equipped with a transparent protective film only on one surface of a polarizer, and may be equipped with a transparent protective film on both surfaces of the polarizer 5 as shown in FIG. By bonding the said easily adhesive film to one surface of a polarizer as a polarizer protective film, the polarizing plate which has a transparent protective film only in one surface of a polarizer is formed. As for the polarizing plate which has a polarizer protective film on both surfaces of a polarizer, the said easily adhesive film should just be bonded by at least one surface of a polarizer. As for a polarizing plate, what the said easily adhesive film was bonded together on both surfaces of a polarizer may be sufficient as it. The polarizer 5 and the easily adhesive film 1 are bonded through the adhesive bond layer 6 .

<Polarizer>

As the polarizer 5, a polyvinyl alcohol (PVA)-based film in which a dichroic substance such as iodine or a dichroic dye is adsorbed to a polyvinyl alcohol-based film such as polyvinyl alcohol or partially formalized polyvinyl alcohol and oriented in one direction A polarizer is used. For example, a PVA type polarizer is obtained by performing iodine dyeing and extending|stretching on a polyvinyl alcohol type film.

In the manufacturing process of the polarizer 5, processing, such as water washing, swelling, and bridge|crosslinking, may be performed as needed. Extending|stretching may be performed either before and after iodine dyeing, and extending|stretching may be performed, dyeing|staining. The stretching may be either stretching in the air (dry stretching) or stretching in water or an aqueous solution containing boric acid, potassium iodide or the like (wet stretching), or these may be used in combination. Although the film thickness in particular of the polarizer 5 is not restrict|limited, Generally, it is about 1-50 micrometers.

As the polarizer 5, a thin PVA-based polarizer having a thickness of 10 µm or less may be used. As a thin-shaped polarizer, it is described, for example in Japanese Unexamined-Japanese-Patent No. 51-069644, Unexamined-Japanese-Patent No. 2000-338329, WO2010/100917 pamphlet, Japanese Patent No. 4691205 specification, Japanese Patent No. 4751481 specification, etc., for example. A thin polarizer is mentioned. These thin polarizers are obtained by the manufacturing method including the process of extending|stretching a PVA-type resin layer and the resin base material for extending|stretching in the state of a laminated body, and the process of iodine dyeing. If it is this manufacturing method, even if the PVA-type resin layer is thin, since it is supported by the resin base material for extending|stretching, it becomes possible to extend|stretch without defects, such as a fracture|rupture by extending|stretching.

<Adhesive>

As long as the adhesive layer 6 used for bonding the polarizer 5 and the easily adhesive film 1 is optically transparent, the material is not particularly limited, and epoxy resin, silicone resin, acrylic resin, 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 the adherend, the adhesive material, and the like. When using the curable adhesive which shows adhesiveness by the crosslinking reaction after application|coating, 0.01-5 micrometers is preferable and, as for the thickness of the adhesive bond layer 6, 0.03-3 micrometers is more preferable.

As the adhesive, various types of adhesives such as water-based adhesives, solvent-based adhesives, hot-melt adhesives, and active energy ray-curable adhesives are used. Among these, since the thickness of an adhesive bond layer can be made small, a water-based adhesive agent or an active energy ray hardening-type adhesive agent is preferable.

Examples of the polymer component of the water-based adhesive include vinyl polymer, gelatin, vinyl latex, polyurethane, polyester, and epoxy. Among these, since it is excellent in the adhesiveness of an easily adhesive film and a polarizer, a vinyl polymer is preferable and polyvinyl alcohol-type resin is especially preferable. Among polyvinyl alcohol-based resins, acetacetyl group-containing polyvinyl alcohol is preferable.

From an adhesive point, about 100-5000 are preferable and, as for the average degree of polymerization of polyvinyl alcohol-type resin, 1000-4000 are more preferable. 85 mol% or more is preferable and, as for the average degree of saponification of polyvinyl alcohol-type resin, 90 mol% or more is more preferable.

The aqueous adhesive composition (solution) may contain a crosslinking agent in addition to the polymer such as polyvinyl alcohol-based resin. As the crosslinking agent, a compound having at least two functional groups per molecule having reactivity with the polymer constituting the adhesive is used. Examples of the crosslinking agent for polyvinyl alcohol-based resins include alkylene diamines; isocyanates; epoxies; aldehydes; and amino-formaldehyde such as methylol urea and methylolmelamine. Among these, amino-formaldehyde is preferable. As the amino-formaldehyde resin, a compound having a methylol group is preferable, and methylolmelamine is particularly preferable. About 10-60 weight part is preferable with respect to 100 weight part of polyvinyl alcohol-type resin, and, as for the compounding quantity of the crosslinking agent in an adhesive composition, 20-50 weight part is more preferable.

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 beams or ultraviolet rays. Especially, since it can be hardened|cured with low energy, the photo-radically polymerizable adhesive agent in which radical polymerization is started by ultraviolet irradiation is preferable.

As a monomer of a radically polymerizable adhesive agent, the compound which has a (meth)acryloyl group, and the compound which has a vinyl group are mentioned. Especially, the compound which has a (meth)acryloyl group is suitable. Examples of the compound 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; Epoxy group-containing (meth)acrylates, such as glycidyl (meth)acrylate, etc. are mentioned. The radically polymerizable adhesive is hydroxyethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, (meth)acrylamide Nitrogen-containing monomers such as amide and (meth)acryloylmorpholine may be included. The radically polymerizable adhesive is a crosslinking component, and includes tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, and dioxane glycol diacrylate. and polyfunctional monomers such as EO-modified diglycerin tetraacrylate.

It is preferable that photocurable adhesives, such as a photo-radically polymerizable adhesive agent, contain a photoinitiator. What is necessary is just to select a photoinitiator suitably according to the reactive species. For example, it is preferable to mix|blend the photoradical generator which produces|generates a radical by light irradiation as a photoinitiator with a radically polymerizable adhesive agent. Content of a photoradical generator is about 0.1-10 weight part normally with respect to 100 weight part of monomers, Preferably it is 0.5-3 weight part. In addition, when using a radically polymerizable adhesive agent as an electron beam curing type, a photoinitiator is not specifically required. A photosensitizer typified by a carbonyl compound or the like may be added to the radically polymerizable adhesive as needed. A photosensitizer is used in order to raise the curing rate and sensitivity by an electron beam. The usage-amount of a photosensitizer is about 0.001-10 weight part normally with respect to 100 weight part of monomers, Preferably it is 0.01-3 weight part.

The adhesive may contain a suitable additive as needed. 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 trapping agents, antioxidants, tackifiers, fillers, plasticizers, leveling agents agents, foaming inhibitors, antistatic agents, heat-resistant stabilizers, hydrolysis-resistant stabilizers, and the like.

[Production of Polarizer]

A polarizing plate is manufactured by bonding the easily adhesive film 1 to one surface (1st main surface) of the polarizer 5 through the adhesive bond layer 6 . As for the easily adhesive film 1, the easily bonding layer formation surface may bond with the polarizer 5 through an adhesive bond layer, and the easily bonding layer non-formation surface may bond it with the polarizer 5 through an adhesive bond layer. 2, by bonding the polarizer 5 to the easily adhesive layer 15 formation surface of the easily adhesive film 1 through the adhesive bond layer 6, a polarizer and a polarizer protective film (easy adhesive film 1) A polarizing plate having high adhesiveness and excellent mechanical strength and durability is obtained. When the easily adhesive layer non-formation surface is bonding with the polarizer 5 through an adhesive bond layer, adhesiveness with other films provided on an easily adhesive film, an adhesive layer, a glass substrate, etc. can be improved.

In bonding of the polarizer 5 and the easily adhesive film 1, after apply|coating an adhesive composition to either one or both of the polarizer 5 and the easily adhesive film 1, the polarizer 5 and the easily adhesive film (1) It is preferable to join by a roll laminator etc., and to harden an adhesive agent. As a coating method of the adhesive composition to the polarizer 5 and/or the easily adhesive film 1, the roll method, the spraying method, the immersion method, etc. are mentioned. Before apply|coating an adhesive composition to the surface of the polarizer 5 and/or the easily adhesive film 1, you may surface treatment, such as a corona treatment, a plasma treatment, and a saponification process.

After bonding the polarizer 5 and the easily adhesive film 1 together, the adhesive bond layer 6 is formed by hardening an adhesive agent according to the kind of adhesive agent. When a water-based adhesive is used, the adhesive is cured by heating and drying. When an active energy ray hardening-type adhesive agent is used, the adhesive agent is hardened by irradiation of active energy rays, such as an electron beam and an ultraviolet-ray.

<Transparent protective film>

The transparent protective film 2 may be bonded to the 2nd main surface of the polarizer 5 via the adhesive bond layer 7 . As the transparent protective film 2, any suitable transparent film can be employ|adopted. The thickness of the transparent protective film 2 is about 5-200 micrometers. From viewpoints of mechanical strength, transparency, handling property, etc., 10-100 micrometers is preferable and, as for the thickness of the transparent protective film 2, 15-60 micrometers is more preferable. The thickness of the easily adhesive film 1 and the transparent protective film 2 may be same or different.

Examples of the material for forming the transparent protective film 2 include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); Cellulose polymers, such as a diacetyl cellulose and a triacetyl cellulose; styrenic polymers such as polystyrene and acrylonitrile-styrene copolymer; Cyclic polyolefins, such as polynorbornene; Polycarbonate etc. are mentioned.

The transparent protective film 2 may be equipped with the easily bonding layer (not shown) on the bonding surface with the polarizer 5. An easily adhesive layer similar to the easily adhesive layer 15 of the easily adhesive film 1 may be provided in the transparent protective film 2 .

As the adhesive layer 7 used for bonding the polarizer 5 and the transparent protective film 2, various types of adhesives such as water-based adhesives, solvent-based adhesives, hot-melt adhesives, and active energy ray-curable adhesives are used. The same adhesive composition may be used for the adhesive bond layer 6 and the adhesive bond layer 7 .

[Use of Polarizer]

You may provide the adhesive layer for bonding to a liquid crystal cell, organic electroluminescent cell, etc. in a polarizing plate. As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer may be appropriately selected and used as the base polymer. In particular, since it is excellent in optical transparency, shows moderate wettability and cohesiveness, and is excellent in weather resistance, heat resistance, etc., an acrylic adhesive is preferable.

Laying of the pressure-sensitive adhesive layer to the polarizing plate can be performed in an appropriate manner. For example, a method of preparing an adhesive solution having a solid content concentration of about 10 to 40% by weight in which a base polymer is dissolved or dispersed in a solvent such as toluene or ethyl acetate, and laid on a polarizing plate, or an adhesive layer formed on a suitable substrate The method of transcribe|transferring on a polarizing plate, etc. are mentioned.

You may provide an adhesive layer on both surfaces of a polarizing plate. When providing an adhesive layer on both surfaces of a polarizing plate, the composition and thickness of the adhesive layer of the front and back may be same or different. The thickness of the pressure-sensitive adhesive layer is generally about 5 to 500 µm.

You may temporarily attach a separator to the surface of an adhesive layer for the purpose of contamination prevention of an adhesive layer, etc. As the separator, a material obtained by coating the surface of the plastic film 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. As an optical layer, a retardation plate, a visual compensation film, a brightness improving film, etc. are mentioned.

An image display apparatus can be formed by bonding a polarizing plate to the surface of image display cells, such as a liquid crystal cell and an organic electroluminescent cell. Formation of a liquid crystal display device is formed by suitably assembling components, such as a liquid crystal cell, a polarizing plate, and an illumination system, as needed, and assembling a drive circuit, etc. In an organic EL display device, by bonding to a circular polarizing plate in which the polarizing plate of the present invention and a retardation film (typically a quarter-wave plate) are bonded to the surface of an organic EL cell, re-emission of reflected light of external light by a metal electrode, etc. reduced, and visibility can be improved.

Example

Hereinafter, although an Example is shown and this invention is demonstrated more concretely, this invention is not limited to these Examples. The description of "%" below is % by weight unless otherwise stated.

[Preparation of easily adhesive composition]

An aqueous polyurethane having a solid content of 34% (“Superflex 210R” manufactured by DKS Co. Ltd.) containing polyester urethane and isophorone diisocyanate as a resin component, and triethylamine as a curing catalyst and methyl ethyl ketone as a dispersion medium 20.6 parts by weight, oxazoline-containing polymer aqueous solution with a solid content of 25% ("Epocros WS-700" manufactured by Nippon Shokubai Co., Ltd.) 5.2 parts by weight, 2.8 parts by weight of 1% by weight aqueous ammonia, colloids with an average primary particle diameter of 35 nm 7.5 parts by weight of a silica 20% aqueous dispersion ("Quartron PL-3" manufactured by Fuso Chemical Industry Co., Ltd.) and 63.9 parts by weight of pure water were mixed to prepare an easily adhesive composition. This easily adhesive composition was an aqueous solution with a concentration of 9.8% containing 15.3 parts by weight of silica particles with respect to 100 parts by weight of the solid content. In the following Examples and Comparative Examples, an easily adhesive layer was formed using this easily adhesive composition.

[Example 1]

The easily adhesive film was produced using the film manufacturing apparatus provided 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 imidized MS resin (glass transition temperature: 120° C.) similar to those used for production of “transparent protective film 1A” described in the examples of Japanese Patent Laid-Open No. 2017-26939 were used. An acrylic resin is melt-extruded from a T-die to form a film with a thickness of 160 µm, the easily adhesive composition is applied to one side of the film with a gravure coater to a wet thickness of about 9 µm, and simultaneously in a heating furnace at a temperature of 140 ° C. It was stretched twice in the longitudinal direction (MD) and the width direction (TD) by a biaxial stretching tenter, respectively, and an easily adhesive film having an easily adhesive layer having a thickness of 50 nm on one side of an acrylic film having a thickness of 40 μm was obtained.

[Examples 2 to 4 and Comparative Examples 1 and 2]

Except having changed the application|coating thickness of an easily bonding composition, it carried out similarly to Example 1, and obtained the easily bonding film. The thickness (after extending|stretching) of an easily bonding layer was as showing in Table 2.

[Examples 5 and 6 and Comparative Examples 3-5]

As shown in Table 2, the furnace temperature (stretching temperature) at the time of tenter extending|stretching was changed. Except having changed extending|stretching temperature, it carried out similarly to Example 1, and obtained the easily adhesive film.

[Comparative Example 6]

An acrylic film with a thickness of 40 µm which was not provided with an easily adhesive layer was obtained without applying the easily adhesive composition in a gravure coater.

[Production of Polarizer]

(Manufacture of polarizer)

A long roll of a 45 μm-thick polyvinyl alcohol (PVA)-based resin film (“PE4500” manufactured by Kuraray Co., Ltd.) was 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 crosslinking bath 1, the crosslinking bath 2, and the washing|cleaning bath shown were conveyed in order, and it was made to dry at 70 degreeC for 5 minutes, and the 18-micrometer-thick polarizer was produced. The iodine concentration and potassium iodide concentration in the dyeing bath were adjusted so that the single transmittance|permeability of a polarizer might be 43.4 %.

(Preparation of UV curing adhesive)

40 parts by weight of N-hydroxyethyl acrylamide and 60 parts by weight of acryloylmorpholine as a curable component, and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane- as a polymerization initiator An ultraviolet curing adhesive containing 3 parts by weight of 1-on ("IRGACURE 819" manufactured by BASF) was prepared.

(bonding of polarizer and polarizer protective film)

The easily adhesive film of each Example and a comparative example was used as a polarizer protective film of one side, and a biaxially stretched cyclic polyolefin film ("ZeonorFilm ZF-14" made by Zeon Corporation) was used as a polarizer protective film of the other surface. The UV curable adhesive is applied to a thickness of about 1 μm on the easily adhesive layer formation surface of the easily adhesive film and the surface of ZeonorFilm, and after bonding to the polarizer with a roll laminator, the adhesive is irradiated with ultraviolet rays with an accumulated light amount of 1000 / mJ / ㎠ was cured to obtain a polarizing plate having an acrylic film (easy-adhesive film) on one surface of the polarizer and ZeonorFilm on the other surface.

[evaluation]

<Amount of Residual Alkali in Easily Adhesive Layer>

The amounts of triethylamine and ammonia remaining in the easily adhesive layer were quantified. The residual amount of triethylamine measured the powder which shaved off the easily adhesive layer from the surface of the easily adhesive film, melt|dissolved in methanol, and quantified by the gas chromatography mass spectrometry (GC/MS) method of a solution. After immersing an easily adhesive film in 25 degreeC pure water, the residual amount of ammonia performed heat extraction for 60 minutes with a 120 degreeC dryer, and quantified the ammonia eluted in water by ion chromatography. The sum total of the quantity of triethylamine and the quantity of ammonia was made into the amount of residual alkali.

<Adhesiveness of the easily adhesive layer>

An adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation) was pressed on the easily adhesive layer-forming surface of the easily adhesive film at a linear pressure of 8 kg/m and a compression speed of 0.3 m/min, and stored at 50° C. for 48 hours. The tip was gripped, a 180° peeling test was performed at a tensile rate of 30 m/min, and the adhesiveness of the easily adhesive layer was determined according to the following criteria.

○: The easily adhesive layer did not peel from the acrylic film, but peeled off at the interface between the adhesive tape and the easily adhesive layer

x: What peeling occurred at the interface of an acrylic film and an easily adhesive layer

<Visual evaluation>

The surface of the easily adhesive film was visually observed, and the presence or absence of local haze (haze rise) by aggregation of a silica particle, and the presence or absence of the flaw in the easily adhesive layer non-formation surface were evaluated.

○: There is no aggregation of silica particles, uniformity in the plane is good, and scratches are not confirmed

Δ: Although turbidity due to aggregation of silica particles was not observed, a wound with a depth of 1 μm or less was confirmed on the non-forming surface of the easily adhesive layer.

×: Cloudiness due to aggregation of silica particles and scratches on the non-forming surface of the easily-adhesive layer were confirmed

<Presence or absence of interfacial layer>

The cross section of the easily adhesive film was observed with a transmission electron microscope (TEM), and the presence or absence of a region (interfacial layer) in which the particles in the easily adhesive layer were embedded in the acrylic film at the interface between the acrylic film and the easily adhesive layer was confirmed. The TEM observation image of Example 3 (with an interface layer) is shown in FIG. 3, and the TEM observation image of Comparative Example 4 (without an interface layer) is shown in FIG.

<Humidification durability of polarizer>

The polarizing plate was cut out to the size of 320 mm x 240 mm, and the surface by the side of a cyclic polyolefin film was bonded together on glass through the 20-micrometer-thick acrylic adhesive. This sample was placed in a constant temperature and humidity chamber at a temperature of 60°C and a relative humidity of 90% (Condition 1), or in a constant temperature and humidity chamber at a temperature of 85°C and a relative humidity of 85% (Condition 2), and held for 500 hours to conduct a heating and humidification endurance test. did.

The polarization degree (P ₀ ) before the endurance test and the polarization degree (P) after the endurance test were measured to calculate the change amount (ΔP)=|PP ₀ | of the polarization degree. Moreover, on the polarizing plate after an endurance test, another polarizing plate was arrange|positioned by orthogonal nicol, it observed visually, the presence or absence of stripe-shaped unevenness was confirmed, and the following criteria evaluated it.

(double-circle): No streaks were observed in the sample after any durability test of condition 1 and condition 2

○: No streaks were observed in the sample after the durability test of Condition 1, and slight streaks were observed in the sample after the durability test of Condition 2

(triangle|delta): In both samples after the endurance test of condition 1 and condition 2, slight streaks were visually recognized.

x: In both samples after the durability test of condition 1 and condition 2, the streaks are clearly visually recognized.

Observation photographs in orthogonal Nicols before and after the endurance test (60°C 90%Rh 500 hours) of the polarizing plates of Example 1 and Comparative Example 2 (taken with "EYESCALE-4W" manufactured by I System Corporation, a non-uniformity measurement system for low luminance) are shown. 5 is shown.

Production conditions of the easily adhesive film of Examples and Comparative Examples (stretching temperature and the thickness of the easily adhesive layer after stretching), evaluation results of the easily adhesive film (visuality, adhesion, presence or absence of an interfacial layer), and durability test results of the polarizing plate (streak of unevenness) Table 2 shows the presence or absence and the amount of change (ΔP) in the degree of polarization.

In the polarizing plate using the acrylic film of Comparative Example 6 in which an easily adhesive layer was not formed, streaks were not observed even after the humidification endurance test, and the decrease in the degree of polarization was small and good optical properties were exhibited. However, the adhesiveness between the acrylic film and the polarizer was low, and peeling of the acrylic film from the polarizer was observed at the end of the polarizing plate after the humidification endurance test.

The easily adhesive film of Comparative Example 2 provided with a 350 nm-thick easily adhesive layer had favorable adhesiveness of an acryl-type film and an easily adhesive layer, and the external appearance of the easily adhesive film was also favorable. However, as for the polarizing plate which used this easily adhesive film as a polarizer protective film, the fall of the polarization degree after a humidification endurance test was large, and the remarkable stripe-shaped nonuniformity was confirmed. Also in Comparative Examples 3-5 where the stretching temperature (heating temperature at the time of forming an easily adhesive layer) was 120° C. or less, similarly to Comparative Example 2, the decrease in the degree of polarization after the humidification endurance test was large, and remarkable stripe-like unevenness was confirmed.

The easily adhesive films of Examples 1-4 in which the easily adhesive layer of 50 nm to 250 nm was formed at the extending|stretching temperature of 140 degreeC did not show the cloudiness resulting from the aggregation of microparticles|fine-particles, but showed favorable external appearance. In addition, although the easily adhesive film of Example 1 showed a fine wound on the non-formed surface of the easily adhesive layer, it was buried by an adhesive or an adhesive at the time of bonding with another member, and it was a level wound which will not become an optical defect. Moreover, compared with the polarizing plate using the easily adhesive film of Comparative Example 2, the polarizing plate using the easily adhesive film of Examples 1-4 was excellent in humidification durability, and generation|occurrence|production of the stripe unevenness was suppressed.

The easily adhesive film of Comparative Example 1 in which an easily adhesive layer having a thickness of 30 nm was formed had good humidification durability of the polarizing plate, but cloudiness due to aggregation of silica particles and damage to the non-formed surface of the easily adhesive layer were observed, and the appearance was deteriorated. It is thought that generation|occurrence|production of a wound originates in the fall of a dispersibility, the silica microparticles|fine-particles fall off from the surface of an easily adhesive layer, and the slidability of an easily adhesive film fell.

From the comparison between Examples 1 to 4 and Comparative Examples 1 and 2, it can be seen that the smaller the thickness of the easily adhesive layer and the smaller the residual alkali component, the more the occurrence of streaks after the humidification endurance test is suppressed, and a polarizing plate excellent in humidification durability is obtained. can On the other hand, when the thickness of an easily adhesive layer is too small and the residual alkali component is too small, it originates in the fall of the dispersibility of microparticles|fine-particles, and it turns out that an appearance defect and the fall of sliding property generate|occur|produce.

In Examples 5 and 6, in which an easily adhesive layer having a thickness of 200 nm was formed at a stretching temperature of 160° C. or 180° C., as in Example 3, the appearance of the easily adhesive film and the humidification durability of the polarizing plate were excellent. On the other hand, in Comparative Examples 3-5 in which an easily adhesive layer having a thickness of 200 nm was formed at a stretching temperature of 80 to 120 ° C., the amount of residual alkali in the easily adhesive layer was large, and as in Comparative Example 2, significant streaks were observed after the humidity endurance test of the polarizing plate.

These results show that an easily adhesive film excellent in the humidification durability of a polarizing plate is obtained when it uses as a polarizer protective film by reducing the amount of residual alkali of an easily adhesive layer in the range which does not reduce the dispersibility of microparticles|fine-particles.

In Comparative Examples 3-5 which extended|stretched at low temperature, the adhesiveness of an acrylic film and an easily adhesive layer was inferior compared with the other example. In Example 3 and the like, at the interface between the acrylic film and the easily adhesive layer, an interface layer in a state in which particles were embedded in the acrylic film (see FIG. 3 ) was formed, whereas in Comparative Examples 3 to 5, an interface layer was not formed. not (see FIG. 4). From these results, by raising the heating temperature after apply|coating an easily bonding composition, in addition to being able to volatilize the alkali component in an easily bonding composition efficiently and being able to reduce the amount of residual alkali, the adhesiveness in the interface of a film base material and an easily bonding layer. can be seen to be improved.

1: easily adhesive film
11: Film substrate
15: easily adhesive layer
2: transparent film
5: Polarizer
6, 7: adhesive layer
100: polarizer

Claims (13)

As an easily adhesive film provided with an easily adhesive layer on the surface of a transparent film base material,
The easily adhesive layer contains a binder resin and colloidal silica having an average primary particle diameter of 10 to 100 nm,
The content of the colloidal silica in the easily adhesive layer is 10 to 50% by weight,
The thickness of the easily adhesive layer is 150 to 280 nm,
The easily adhesive film whose total content of the amine and ammonia of the said easily adhesive layer is 20-75 ppm. delete The method of claim 1,
The easily adhesive film whose content of the said colloidal silica in the said easily adhesive layer is 12 to 30 weight%. The method of claim 1,
An easily adhesive film wherein the transparent film substrate is an acrylic film. The method of claim 1,
The easily adhesive film wherein the binder resin of the easily adhesive layer is a urethane-based resin. The method of claim 1,
An easily adhesive film in which a region in which the colloidal silica is embedded in the transparent film substrate is present at the interface between the transparent film substrate and the easily adhesive layer. A method for producing the easily adhesive film according to any one of claims 1 and 3 to 6,
An easily adhesive composition containing a binder resin or a precursor thereof, colloidal silica having an average primary particle diameter of 10 to 100 nm, at least one alkali component selected from the group consisting of amines and ammonia, and a solvent on the surface of the transparent film substrate spread,
A method for producing an easily adhesive film in which the solvent and the alkali component are volatilized by heating the easily adhesive composition at a temperature 10° C. or more higher than the glass transition temperature of the transparent film substrate. 8. The method of claim 7,
The method for producing an easily adhesive film wherein the alkali component has a dispersion promoting action of the colloidal silica. 8. The method of claim 7,
The easily-adhesive composition contains a polyurethane precursor as a precursor of the binder resin, and a tertiary amine as the alkali component. 8. The method of claim 7,
The method for producing an easily adhesive film in which the easily adhesive composition contains an amine having a boiling point of 150° C. or less as the alkali component. 8. The method of claim 7,
A method for producing an easily adhesive film, wherein the transparent film substrate coated with the easily adhesive composition is stretched in at least one direction while the easily adhesive composition is heated at a temperature 10° C. or more higher than the glass transition temperature of the transparent film substrate. 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 through an adhesive layer;
The said transparent film is a polarizing plate whose easily adhesive film in any one of Claims 1 and 3-6. The image display device which has an image display cell and the polarizing plate of Claim 12.

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