CN110542943A - Polarizing film with adhesive layer, method for producing same, and image display device - Google Patents

Abstract

The invention provides a polarizing film with an adhesive layer, which sequentially comprises a polarizer, a tackifying coating layer containing polyvinyl alcohol resin and the adhesive layer, wherein even if the adhesive layer does not contain isocyanate crosslinking agent, the tackifying coating layer and the adhesive layer have good anchoring force. The polarizing film with an adhesive layer of the present invention comprises a polarizer, a tie coat layer and an adhesive layer in this order, wherein the tie coat layer is formed from an aqueous resin composition comprising an aqueous resin and a compound (a) having at least one primary alcohol capable of reacting with a hydroxyl group at a molecular end, and the adhesive layer is formed from an adhesive composition comprising: a base polymer having a hydroxyl group, and a mercapto group-containing silane coupling agent.

Description

Polarizing film with adhesive layer, method for producing same, and image display device

The present application is a divisional application of the present application entitled "polarizing film with adhesive layer, method for producing the same, and image display device" filed 2016, 27/9/2016 and under the name of 201680003216.0.

Technical Field

The present invention relates to a polarizing film with an adhesive layer and a method for manufacturing the same. The polarizing film with an adhesive layer can be used alone or as an optical film obtained by laminating the polarizing film with an adhesive layer to form an image display device such as a Liquid Crystal Display (LCD) or an organic EL display device.

Background

In a liquid crystal display device or the like, it is essential to dispose polarizing elements on both sides of a liquid crystal cell in view of an image forming method, and polarizing films are generally bonded thereto. When the polarizing film is attached to the liquid crystal cell, an adhesive is generally used. In order to reduce light loss, the polarizing film and the liquid crystal cell are generally bonded to each other with an adhesive. In such a case, a polarizing film with an adhesive layer, in which an adhesive is provided as an adhesive layer on one side of the polarizing film in advance, is generally used because of advantages such as no need for a drying process to fix the polarizing film. A release film is generally adhered to the adhesive layer of the polarizing film with the adhesive layer.

The pressure-sensitive adhesive layer is usually formed using a pressure-sensitive adhesive containing a base polymer and a crosslinking agent. As the base polymer, an acrylic polymer is preferably used, and as the crosslinking agent, an isocyanate-based crosslinking agent is preferably used.

in view of the reduction in thickness, a polarizing film with an adhesive layer using a one-side protective polarizing film having a protective film provided only on one surface of a polarizer has been proposed. However, the polarizing film with an adhesive layer using a one-side protective polarizing film has the following problems: in a severe environment such as thermal shock (for example, a 250-hour test at 95 ℃), excessive stress is generated inside the polarizer due to the difference between the shrinkage stress of the polarizer on the side where the protective film is provided and the shrinkage stress of the polarizer on the opposite side to the protective film, and various cracks including a minute crack of several hundred μm or a through crack penetrating the entire surface are easily generated in the absorption axis direction of the polarizer. That is, the one-side protective polarizing film with an adhesive layer has insufficient durability under the above severe environment.

from the viewpoint of suppressing the occurrence of the through crack, and making the thickness and weight of the polarizer thinner, it has been proposed to provide a protective layer made of a water-soluble film-forming composition (polyvinyl alcohol resin composition) on at least one surface of the polarizer (patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-043858

Disclosure of Invention

Problems to be solved by the invention

When a protective layer (anchor coat layer) made of a polyvinyl alcohol resin composition is provided as described above and an adhesive layer containing an isocyanate-based crosslinking agent is provided on the protective layer, the protective layer and the adhesive layer have a good anchoring force by the reaction of hydroxyl groups derived from the polyvinyl alcohol resin in the protective layer and isocyanate groups derived from the isocyanate-based crosslinking agent in the adhesive layer.

However, in order to provide the adhesive layer containing the isocyanate-based crosslinking agent with hardness corresponding to scratch resistance and workability and to ensure anchoring force, a predetermined aging time is required after the adhesive layer is formed and before shipment. In addition, the adhesive composition containing an isocyanate-based crosslinking agent has the following problems because it undergoes a self-crosslinking reaction: the adhesive composition has a pot life and is difficult to handle. On the other hand, an adhesive composition containing no isocyanate-based crosslinking agent cannot sufficiently satisfy the anchoring property with a anchor coat layer formed of a polyvinyl alcohol-based resin composition.

The purpose of the present invention is to provide a polarizing film with an adhesive layer, which comprises a polarizer, a tie coat layer containing an aqueous resin, and an adhesive layer in this order, and which has good anchoring force between the tie coat layer and the adhesive layer even if the adhesive layer does not contain an isocyanate-based crosslinking agent.

Another object of the present invention is to provide a method for producing the above polarizing film with an adhesive layer. Further, the present invention relates to an image display device having the above polarizing film with an adhesive layer.

Means for solving the problems

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following polarizing film with an adhesive layer, and the like, and have completed the present invention.

That is, the present invention relates to a polarizing film with an adhesive layer, comprising a polarizer, a tie coat layer and an adhesive layer in this order,

The anchor coat layer is formed from an aqueous resin composition containing an aqueous resin and a compound (a) having at least one primary alcohol capable of reacting with a hydroxyl group at the molecular terminal,

The adhesive layer is formed from an adhesive composition comprising: a base polymer having a hydroxyl group, and a mercapto group-containing silane coupling agent.

In the polarizing film with an adhesive layer, at least one selected from the group consisting of polyvinyl alcohol resins, polyurethane resins, and oxazoline group-containing polymers can be used as the aqueous resin. The water-based resin is preferably a polyvinyl alcohol resin. The polyvinyl alcohol resin preferably has a saponification degree of 96 mol% or more and an average polymerization degree of 2000 or more.

In the polarizing film with an adhesive layer, the aqueous resin composition preferably contains 0.2 to 20 parts by weight of the compound (a) per 100 parts by weight of the aqueous resin.

In the polarizing film with an adhesive layer, as the compound (a), methylolmelamine can be preferably used.

In the polarizing film with an adhesive layer, the thickness of the anchor coat layer is preferably 0.05 μm or more and 6 μm or less.

In the polarizing film with an adhesive layer, a (meth) acrylic polymer having a hydroxyl group may be used as the base polymer having a hydroxyl group.

In the polarizing film with an adhesive layer, the adhesive composition preferably contains 0.01 to 5 parts by weight of the mercapto group-containing silane coupling agent per 100 parts by weight of the hydroxyl group-containing base polymer.

In the polarizing film with an adhesive layer, the adhesive composition may contain a crosslinking agent. It is preferable to contain a crosslinking agent (b) which does not react with a hydroxyl group as the crosslinking agent. The crosslinking agent (b) which does not react with a hydroxyl group is preferably a peroxide.

In the polarizing film with an adhesive layer, the adhesive composition preferably contains 0.01 to 2 parts by weight of the crosslinking agent (b) which does not react with a hydroxyl group, based on 100 parts by weight of the base polymer having a hydroxyl group.

In the polarizing film with an adhesive layer, the thickness of the polarizer is preferably 15 μm or less.

In the polarizing film with an adhesive layer, the polarizer is preferably configured such that optical properties represented by a monomer transmittance T and a polarization degree P satisfy the following conditions,

P > - (100.929T-42.4-1). times.100 (wherein, T < 42.3), and

P is more than or equal to 99.9 (wherein, T is more than or equal to 42.3).

The polarizing film with an adhesive layer may have a protective film on at least one side of the polarizer.

In the polarizing film with an adhesive layer, a separator may be laminated on the adhesive layer.

The present invention also relates to a method for producing the above polarizing film with an adhesive layer, comprising the steps of:

A step of forming an anchor coat layer by applying an aqueous resin composition containing an aqueous resin and a compound (a) having at least one primary alcohol capable of reacting with a hydroxyl group at a molecular end, onto a polarizer and then drying the aqueous resin composition; and

and a step of forming a pressure-sensitive adhesive layer on the anchor coat layer from a pressure-sensitive adhesive composition containing: a base polymer having a hydroxyl group, and a mercapto group-containing silane coupling agent.

The present invention also relates to an image display device having the polarizing film with an adhesive layer.

ADVANTAGEOUS EFFECTS OF INVENTION

The polarizing film with an adhesive layer of the present invention comprises a polarizer, a tie coat layer containing an aqueous resin, and an adhesive layer in this order. The anchor coat layer contains a compound (a) having at least one primary alcohol capable of reacting with a hydroxyl group at the molecular end, such as methylolmelamine, and the adhesive layer contains a mercapto group-containing silane coupling agent. It is considered that the terminal primary alcohol of methylolmelamine or the like in the anchor coat layer reacts with the aqueous resin (for example, polyvinyl alcohol resin) of the anchor coat layer, and reacts with the silanol group of the mercapto group-containing silane coupling agent in the pressure-sensitive adhesive layer. In addition, when the anchor coat layer is provided directly on the polarizer, it is considered that a primary alcohol at the terminal of methylolmelamine or the like in the anchor coat layer reacts with a hydroxyl group derived from the polyvinyl alcohol-based resin in the polarizer. In addition, it is considered that the silanol group of the mercapto group-containing silane coupling agent reacts with the hydroxyl group derived from the base polymer in the adhesive layer. It is also considered that the mercapto group-containing silane coupling agent is self-condensed in the pressure-sensitive adhesive layer by the reaction between mercapto groups (-SH, thiol groups), thereby forming a thioether bond, and the crosslinking of the pressure-sensitive adhesive layer can be improved. Therefore, it is considered that the anchor coat layer and the adhesive layer have good anchoring properties even if the adhesive layer does not contain an isocyanate-based crosslinking agent because the materials in the anchor coat layer and the adhesive layer react and bond.

Drawings

FIG. 1 is an example of a schematic cross-sectional view of a polarizing film with an adhesive layer of the present invention.

FIG. 2 is an example of a schematic cross-sectional view of a polarizing film with an adhesive layer of the present invention.

FIG. 3 is an example of a schematic cross-sectional view of a polarizing film with an adhesive layer of the present invention.

Description of the symbols

1 polarizer

2 tackifying coating (polyvinyl alcohol resin as main component)

3 adhesive layer

4 diaphragm

5. 5' protective film

10 polarizing film with adhesive layer

11 polarizing film with adhesive layer

Detailed Description

Next, polarizing films 10, 11, and 12 with an adhesive layer according to the present invention will be described with reference to fig. 1 to 3. Polarizing films 10, 11, and 12 with an adhesive layer have a polarizer 1, a tie coat layer 2 containing an aqueous resin, and an adhesive layer 3 in this order. As shown in fig. 1 and 2, the polarizing films 10 and 11 with an adhesive layer of the present invention may be provided with a tie coat layer 2 directly on the polarizer 1, the tie coat layer 2 being formed of an aqueous resin composition containing an aqueous resin. As shown in fig. 2 and 3, protective films 5 and 5' may be provided on one side or both sides of the polarizer 1. Fig. 2 illustrates a case where the polarizing film 10 with an adhesive layer has a protective film 5 on the side opposite to the side of the polarizer 1 on which the anchor coat layer 2 is provided. Fig. 3 illustrates a polarizing film 10 with an adhesive layer having protective films 5 and 5 'on both sides of the polarizer 1 and a tie coat layer 2 on the protective film 5' side. Although not shown in fig. 2 and 3, the polarizer 1 and the protective film 5 are laminated with an interlayer such as an adhesive layer, and an undercoat layer (primer layer) interposed therebetween. Although not shown, an easy-adhesion layer may be provided on the protective films 5 and 5 ', or the protective films 5 and 5' may be subjected to activation treatment to laminate the easy-adhesion layer and the adhesive layer.

In the polarizing films 10 and 11 with an adhesive layer of the present invention, the separator 4 may be provided on the adhesive layer 3 as shown in fig. 1 to 3. In the case where the polarizing film 11 with an adhesive layer has the protective film 5 as shown in fig. 2 and 3, a surface protective film may be provided on the protective film 5.

< polarizer >

The polarizer is not particularly limited, and various polarizers can be used. Examples of the polarizer include films obtained by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene-vinyl acetate copolymer partially saponified films, and polyene oriented films such as dehydrated polyvinyl alcohol films and desalted polyvinyl chloride films, in which a dichroic substance such as iodine or a dichroic dye is adsorbed. Among these, a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine is preferable. The thickness of these polarizers is not particularly limited, but is usually 2 to 25 μm.

The polarizer obtained by uniaxially stretching a polyvinyl alcohol film dyed with iodine can be produced by, for example, dyeing a polyvinyl alcohol film by immersing the film in an aqueous iodine solution and stretching the film to 3 to 7 times the original length. If necessary, the substrate may be immersed in an aqueous solution of potassium iodide or the like optionally containing boric acid, zinc sulfate, zinc chloride or the like. If necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol film with water, it is possible to clean dirt and an anti-blocking agent on the surface of the polyvinyl alcohol film, and also possible to swell the polyvinyl alcohol film to prevent unevenness such as uneven dyeing. The stretching may be performed after the dyeing with iodine, or may be performed while dyeing, or may be performed after the stretching with iodine. Stretching may be performed in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

As the polarizer, a thin polarizer having a thickness of 15 μm or less can be used. From the viewpoint of reduction in thickness and resistance to cracks due to thermal shock, the thickness of the polarizer is preferably 12 μm, more preferably 10 μm or less, still more preferably 8 μm or less, still more preferably 7 μm or less, and still more preferably 6 μm or less. On the other hand, the thickness of the polarizer is preferably 2 μm or more, more preferably 3 μm or more. Such a thin polarizer has a small variation in thickness, is excellent in visibility, and has a small dimensional change, thereby having excellent durability against thermal shock.

Typical examples of the thin polarizer having a thickness of 15 μm or less include thin polarizing films (polarizers) described in japanese patent No. 4751486, japanese patent No. 4751481, japanese patent No. 4815544, japanese patent No. 5048120, japanese patent No. 5587517, international publication No. 2014/077599, international publication No. 2014/077636, and the like, and thin polarizing films (polarizers) obtained by the production method described in the above documents.

The polarizer is preferably configured such that optical characteristics represented by a monomer transmittance T and a polarization degree P satisfy the following conditions of P > - (100.929T-42.4-1). times.100 (where T < 42.3) and P.gtoreq.99.9 (where T.gtoreq.42.3). Mainly, a polarizing film configured to satisfy the above conditions has performance required as a display for a liquid crystal television using a large-sized display element. Specifically, the contrast ratio is 1000:1 or more and the maximum luminance is 500cd/m2 or more. For other applications, for example, the organic EL display device is attached to the visible side of the organic EL display device.

As the thin polarizing film, a thin polarizing film obtained by a production method including a step of stretching in an aqueous boric acid solution as described in japanese patent specification 4751486, japanese patent specification 4751481, and patent 4815544 is preferable, and a thin polarizing film obtained by a production method including a step of stretching in an auxiliary gas atmosphere before stretching in an aqueous boric acid solution as described in japanese patent specification 4751481 and patent 4815544 is particularly preferable, in view of improving polarizing performance by stretching at a high magnification also in a production method including a step of stretching in a laminated state and a step of dyeing. These thin polarizing films can be obtained by a production method including a step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as PVA-based resin) layer and a stretching resin base material in a state of a laminate, and a step of dyeing. According to this production method, even if the PVA-based resin layer is thin, it can be stretched without causing troubles such as breakage due to stretching, because it is supported by the resin base material for stretching.

< protective film >

As a material constituting the protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferable. Examples thereof include: polyester polymers such AS polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such AS cellulose diacetate and cellulose triacetate, acrylic polymers such AS polymethyl methacrylate, styrene polymers such AS polystyrene and acrylonitrile-styrene copolymer (AS resin), and polycarbonate polymers. Examples of the polymer for forming the protective film include polyolefin polymers such as polyethylene, polypropylene, ring-based or norbornene-based polyolefins, ethylene-propylene copolymers, vinyl chloride polymers, amides polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aromatic ester polymers, polyacetal polymers, epoxy polymers, and blends of the above polymers. These protective films are generally bonded to the polarizer with an adhesive layer. In addition, the protective film may be formed as follows: a thermosetting resin or an ultraviolet-curable resin such as a (meth) acrylic resin, a urethane resin, an acrylic urethane resin, an epoxy resin, or a silicone resin is applied to a polarizer and cured.

As the protective film, a retardation film can be used. Examples of the retardation film include a retardation film having a front retardation of 40nm or more and/or a thickness direction retardation of 80nm or more. The front phase difference is usually controlled within a range of 40 to 200nm, and the thickness direction phase difference is usually controlled within a range of 80 to 300 nm. When the retardation film is used as the protective film, the retardation film also functions as a polarizer protective film, and therefore, the thickness can be reduced.

examples of the retardation film include a birefringent film obtained by subjecting a thermoplastic resin film to a uniaxial stretching treatment or a biaxial stretching treatment. The temperature and stretch ratio of the stretching can be appropriately set depending on the retardation value, the material and thickness of the film.

The thickness of the protective film may be suitably determined, but is preferably 3 to 200 μm, more preferably 3 to 100 μm, in view of strength, workability such as handling, and thin layer property. Particularly, the thickness of the protective film (when the film is formed in advance) is preferably 10 to 60 μm, and more preferably 10 to 45 μm, from the viewpoint of transportability. On the other hand, the thickness of the protective film (formed by coating and curing) is preferably 3 to 25 μm, and more preferably 3 to 20 μm, from the viewpoint of transportability. The protective film may be used in a plurality of or a plurality of layers.

a functional layer such as a hard coat layer, an antireflection layer, an adhesion prevention layer, a diffusion layer, or an antiglare layer may be provided on the surface of the protective film to which the polarizer is not bonded. The functional layers such as the hard coat layer, the antireflection layer, the adhesion prevention layer, the diffusion layer, and the antiglare layer may be provided as a protective film itself, or may be provided separately from the transparent protective film.

< sandwiching layer >

The protective film and the polarizer may be laminated with an interlayer such as an adhesive layer, and an undercoat layer (primer layer) interposed therebetween. In this case, it is desirable to stack the two layers without an air gap by the interlayer.

The adhesive layer is formed by an adhesive. The type of the adhesive is not particularly limited, and various adhesives can be used. The adhesive layer is not particularly limited as long as it is optically transparent, and various types of adhesives such as water-based, solvent-based, hot-melt, and active energy ray-curable adhesives can be used as the adhesive, but a water-based adhesive or an active energy ray-curable adhesive is preferable.

Examples of the aqueous adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, and aqueous polyesters. The aqueous adhesive is usually used in the form of an aqueous adhesive, and usually contains 0.5 to 60% by weight of a solid content.

The active energy ray-curable adhesive is an adhesive that is cured by an active energy ray such as an electron beam or ultraviolet ray (radical-curable type or cation-curable type), and can be used in the form of, for example, an electron beam-curable type or an ultraviolet-curable type. As the active energy ray-curable adhesive, for example, a photo radical-curable adhesive can be used. When a photo radical curing active energy ray-curable adhesive is used as an ultraviolet curing adhesive, the adhesive contains a radical polymerizable compound and a photopolymerization initiator.

When an aqueous adhesive or the like is used for the application of the adhesive, the adhesive layer to be finally formed is preferably made to have a thickness of 30 to 300 nm. The thickness of the adhesive layer is more preferably 60 to 250 nm. On the other hand, when the active energy ray-curable adhesive is used, the thickness of the adhesive layer is preferably 0.1 to 200 μm, more preferably 0.5 to 50 μm, and still more preferably 0.5 to 10 μm.

When the polarizer and the protective film are laminated, an easy-adhesion layer may be provided between the protective film and the adhesive layer.

< adhesion promoting coating >

The tie coat layer contains a water-based resin. The anchor coat layer can be formed by, for example, applying an aqueous resin composition containing an aqueous resin to the polarizer. As the aqueous resin, for example, at least one selected from the group consisting of polyvinyl alcohol resins, polyurethane resins, and oxazoline group-containing polymers can be used. Among these, in the case where a tie coat layer is formed directly on the polarizer as shown in fig. 1 and 2, a polyvinyl alcohol-based resin is preferable as the aqueous resin from the viewpoint of suppressing the occurrence of through cracks. On the other hand, when a tie coat layer is formed on the protective film as shown in fig. 3, the aqueous resin is preferably a urethane resin or an oxazoline group-containing polymer from the viewpoint of film formability and wettability with respect to the protective film.

Examples of the polyvinyl alcohol resin include polyvinyl alcohol. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Examples of the polyvinyl alcohol resin include saponified copolymers of vinyl acetate and copolymerizable monomers. When the copolymerizable monomer is ethylene, an ethylene-vinyl alcohol copolymer can be obtained. Examples of the copolymerizable monomer include unsaturated carboxylic acids such as maleic acid (anhydride), fumaric acid, crotonic acid, itaconic acid, and (meth) acrylic acid, and esters thereof; α -olefins such as ethylene and propylene, (meth) acrylic acid (sodium) (monoalkyl maleate) sodium sulfonate, alkyl maleate disulfonic acid sodium, N-methylolacrylamide, alkali metal salts of acrylamide alkylsulfonic acid, N-vinylpyrrolidone derivatives, and the like. These polyvinyl alcohol resins may be used alone or in combination of two or more. From the viewpoint of controlling the crystal melting heat of the anchor coat layer to 30mj/mg or more so as to satisfy the moist heat resistance and the water resistance, polyvinyl alcohol obtained by saponifying polyvinyl acetate is preferable.

The polyvinyl alcohol resin may be used in a degree of saponification of, for example, 95 mol% or more, and from the viewpoint of satisfying the moist heat resistance and water resistance, the degree of saponification is preferably 96 mol% or more, more preferably 99 mol% or more, and still more preferably 99.5 mol% or more. The degree of saponification indicates the proportion of units which are actually saponified to vinyl alcohol units among the units which can be converted to vinyl alcohol units by saponification, and the residue is a vinyl ester unit. The degree of saponification can be determined in accordance with JIS K6726-.

The polyvinyl alcohol resin may have an average degree of polymerization of, for example, 500 or more, and from the viewpoint of satisfying the moist heat resistance and water resistance of the anchor coat layer, the average degree of polymerization is preferably 1000 or more, more preferably 1500 or more, and still more preferably 2000 or more. The average polymerization degree of the polyvinyl alcohol resin was measured in accordance with JIS-K6726.

As the polyvinyl alcohol resin, a modified polyvinyl alcohol resin having a hydrophilic functional group in a side chain of the polyvinyl alcohol or a copolymer thereof can be used. Examples of the hydrophilic functional group include an acetoacetyl group and a carbonyl group. Further, a modified polyvinyl alcohol obtained by acetalization, urethanization, etherification, grafting, phosphorylation or the like of a polyvinyl alcohol resin may be used.

As the polyurethane resin, an emulsion of the polyurethane resin may be used. As the resin emulsion of polyurethane, an emulsion obtained by self-emulsification without using an emulsifier can be used.

As the polyurethane resin, for example, a one-component type polyurethane resin obtained by a polyaddition reaction of a polymer polyol and an isocyanate compound can be used. As the one-component type polyurethane resin, for example, polyether polyurethane resin, polyester polyurethane resin, or the like can be used. The polyurethane resin is preferably a polyurethane resin having a hydroxyl group remaining therein. Specifically, for example, a lacquer type polyurethane resin can be mentioned. The polyurethane resin may be formed into a film by merely drying to remove the solvent or water.

The polyether polyurethane resin is generally obtained by addition polymerization of a polyether polyol and an isocyanate compound. The polyether polyol is obtained by addition of 1 or 2 or more kinds of polyols to alkylene oxide by ring-opening polymerization. The polyester-based polyurethane resin is generally obtained by a polyaddition reaction of a polyester polyol and an isocyanate compound. The polyester polyol is obtained by polycondensing a polyol with a polybasic acid. The polymer polyol such as polyether polyol or polyether polyol preferably has a number average molecular weight of 400 to 3000, more preferably 500 to 2000. The polymer polyol such as polyether polyol and polyester polyol may be used alone in 1 kind or may be a copolymer obtained by using 2 or more kinds.

as the isocyanate compound, aromatic, araliphatic, aliphatic, alicyclic or other isocyanates generally used in polyurethane can be suitably used. Further, as the isocyanate compound, an adduct, a dimer, a trimer, a polymer thereof, or the like of the above isocyanate compound can also be used. Further, as the isocyanate compound, a modified isocyanate obtained by urethanizing, uretdionizing, carbodiimidizing, or the like, a part of the above isocyanate may be used.

When the polyurethane resin is dispersed in water, a method of forcibly emulsifying and dispersing the resin using an emulsifier to adjust the dispersion is known. In addition, a self-emulsifying substance obtained by introducing an anionic group, a cationic group, or a nonionic group, which is a water-dispersible hydrophilic group, into the resin may be used. Further, an ionic polymer complex may be used.

examples of the resin emulsion of polyurethane include Adeka Bon-Tighter HUX series manufactured by Asahi Denka Co., Ltd, which is self-emulsified without using an emulsifier. Specific examples of the aqueous polyurethane resin include SUPERFLEX series manufactured by first Industrial pharmaceutical Co., Ltd, and TAKELAC W-6020 manufactured by Mitsui chemical polyurethane Co., Ltd.

As the epoxy resin, an emulsion of the epoxy resin may be used. When the epoxy resin is dispersed in water, a method of forcibly emulsifying and dispersing the resin using an emulsifier to adjust the dispersion is known. Examples of the epoxy Resin include Adeka Resin EM series manufactured by ADEKA, Celloxide 2021P manufactured by Dailk corporation, and the like.

Examples of the oxazoline group-containing polymer include a polymer having a main chain composed of an acrylic skeleton or a styrene skeleton and having an oxazoline group in a side chain of the main chain. Among the above, an oxazoline group-containing acrylic polymer which contains a main chain composed of an acrylic skeleton and has an oxazoline group in a side chain of the main chain is preferable.

Examples of the oxazoline group include a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group, and among these, a 2-oxazoline group is preferable. The 2-oxazolinyl group is generally represented by the following general formula (1).

[ chemical formula 1]

(wherein R1-R4 each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, a phenyl group or a substituted phenyl group.)

The oxazoline group-containing polymer may have a polyoxyalkylene group in addition to the oxazoline group.

The oxazoline group-containing polymer preferably has a number average molecular weight of 5,000 or more, more preferably 10,000 or more, and usually preferably 1,000,000 or less. When the number average molecular weight is less than 5,000, the anchor strength may not be improved because the anchor strength is not sufficiently high and the anchor strength may be broken due to cohesion. When the number average molecular weight is more than 1,000,000, workability may be deteriorated. The oxazoline group-containing polymer preferably has an oxazoline number of, for example, 1,500g of sol/eq.or less, more preferably 1,200g of sol/eq.or less. When the oxazoline value is more than 1,500g solid/eq, the amount of oxazoline groups contained in the molecule may be small, and the anchoring force may not be improved.

since the oxazoline group-containing polymer reacts with a hydroxyl group contained in the adhesive composition at a relatively low temperature, if the oxazoline group-containing polymer is contained in the anchor coat layer, it can react with a functional group or the like in the adhesive layer to strongly adhere thereto.

Specific examples of the oxazoline group-containing polymer include: oxazoline group-containing acrylic polymers such as EPOCROS WS-300, EPOCROS WS-500 and EPOCROS WS-700 manufactured by Nippon catalysts K-1000 series and EPOCROS K-2000 series manufactured by Nippon catalysts K-K, and the like, and they may be used alone in 1 kind or in combination of 2 or more kinds.

The anchor coat layer of the present invention is formed of the aqueous resin composition containing an aqueous resin as a main component, and the aqueous resin composition contains a compound (a) having at least one primary alcohol capable of reacting with a hydroxyl group at a molecular end. By introducing the compound (a) into the anchor coat layer, as described above, the reaction with the mercapto group-containing silane coupling agent and the hydroxyl group-containing base polymer in the adhesive composition for forming the adhesive layer proceeds, and the anchoring force between the anchor coat layer and the adhesive layer can be improved.

The aqueous resin preferably does not have a functional group reactive with the primary alcohol capable of reacting with a hydroxyl group of the compound (a), and among the aqueous resins exemplified above, a polyvinyl alcohol resin is preferred, and an unmodified polyvinyl alcohol resin is particularly preferred. Alternatively, when an unmodified polyvinyl alcohol resin is used, the hydrophilic functional group involved in the modification preferably has a reactivity with the primary alcohol capable of reacting with a hydroxyl group, which the compound (a) has, lower than the reactivity with the functional group (silanol group) of the mercapto group-containing silane coupling agent in the adhesive composition.

The compound (a) is preferably blended in a proportion of, for example, 0.2 to 20 parts by weight based on 100 parts by weight of the aqueous resin. From the viewpoint of improving the anchoring force, the proportion of the compound (a) is preferably 0.2 parts by weight or more. The proportion of the compound (a) is preferably 1 part by weight or more, more preferably 3 parts by weight or more. On the other hand, if the proportion of the compound (a) is increased, the water resistance and the appearance (appearance that is observed as unevenness in a polarizing film) are deteriorated, and therefore, the proportion of the compound (a) is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and still more preferably 7 parts by weight or less. The proportion of the above-mentioned compound (a) is determined by the kind of the hydroxyl group-containing base polymer and the mercapto group-containing silane coupling agent used in the adhesive composition.

The proportion of the aqueous resin in the anchor coat layer or the aqueous resin composition (solid content) is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight or more.

As the compound (a), a compound having at least one primary alcohol at the molecular end can be preferably used. Examples of the compound include: amino-formaldehyde resins such as methylol urea, methylol melamine, and condensates of alkylated methylol urea with formaldehyde, ethylene glycol, glycerin, 1, 6-hexanediol, 1, 8-octanediol, aliphatic alcohols, and polyethylene glycols. Of these, amino-formaldehyde resins having methylol groups are preferred, of which methylolmelamine is suitable.

In addition, a compound having a functional group capable of reacting with a hydroxyl group other than the compound (a) can be used. For example, a compound having an amino group at the molecular end is exemplified. Examples of the compound include: alkylene diamines having an alkylene group and 2 amino groups, such as ethylene diamine, triethylene diamine, and hexamethylene diamine; hydrazine; dicarboxylic acid dihydrazides such as adipic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, and itaconic acid dihydrazide; and water-soluble dihydrazides such as 1,2-dihydrazine (ethylene-1,2-dihydrazine), 1,3-dihydrazine (propylene-1,3-dihydrazine), and 1, 4-dihydrazinebutane (butylene-1, 4-dihydrazine). Of these, hydrazine is preferred. The compound having an amino group at the molecular end is suitable, for example, in the case where the base polymer of the adhesive composition has a hydroxyl group (in the case where the base polymer is a (meth) acrylic polymer, a monomer containing a hydroxyl group is contained as a monomer unit).

In addition, examples of the compound having a functional group capable of reacting with a hydroxyl group other than the compound (a) include: isocyanates such as tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane triisocyanate), isophorone isocyanate, and ketoxime blocked products or phenol blocked products thereof; epoxies such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether or glycerol triglycidyl ether, 1, 6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, and diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde and butyraldehyde; dialdehydes such as glyoxal, malondialdehyde, succindialdehyde, glutaraldehyde, maledialdehyde, and phthalaldehyde; amino-formaldehyde resins such as alkylated methylolated melamine, methyl guanamine, condensates of phenylguanamine and formaldehyde; and salts of divalent or trivalent metals such as sodium, potassium, magnesium, calcium, aluminum, iron, and nickel, and oxides thereof. Among these, amino-formaldehyde resins and water-soluble dihydrazines are preferable.

From the viewpoint of improving water resistance and controlling elastic modulus, a compound having a functional group capable of reacting with a hydroxyl group other than the compound (a) may be used in a proportion of 20 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less, relative to 100 parts by weight of the aqueous resin.

The aqueous resin composition may be prepared by dissolving the aqueous resin in a solvent to prepare a solution. Examples of the solvent include: water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide and N-methylpyrrolidone. These solvents may be used alone or in combination of two or more. Among these, an aqueous solution prepared using water as a solvent is preferred. The concentration of the aqueous resin in the aqueous resin composition (e.g., aqueous solution) is not particularly limited, and is 0.1 to 15% by weight, preferably 0.5 to 10% by weight, in consideration of coatability, stability in standing, and the like.

In addition, other than the compound (a), for example, a surfactant may be added to the aqueous resin composition (for example, an aqueous solution). Examples of the surfactant include nonionic surfactants. In addition, stabilizers such as various tackifiers, ultraviolet absorbers, antioxidants, heat stabilizers and hydrolysis stabilizers may be added.

the thickness of the anchor coat layer is preferably 0.05 μm or more, more preferably 0.2 μm or more, and the thickness of the anchor coat layer is preferably 0.5 μm or more, more preferably 0.7 μm or more. In particular, when a polyvinyl alcohol resin is used as the aqueous resin, the thickness of the anchor coat layer is preferably 0.2 μm or more, and the occurrence of cracks due to thermal shock can be suppressed by using the anchor coat layer having such a thickness. On the other hand, if the anchor coat layer is too thick, the optical reliability and water resistance are lowered, and therefore the thickness of the anchor coat layer is preferably 6 μm or less, more preferably 5 μm or less, still more preferably 3 μm or less, and still more preferably 2 μm or less.

The anchor coat layer can be formed by applying the aqueous resin composition to the other surface (surface having no protective film) of the polarizer and drying the resultant coating. The aqueous resin composition is applied in a thickness after drying (preferably 0.2 μm to 6 μm). The coating operation is not particularly limited, and any suitable method may be employed. Various methods such as roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and doctor blade coating (comma coating) can be used.

< adhesive layer >

the adhesive layer is formed from an adhesive composition containing a base polymer having hydroxyl groups and a mercapto group-containing silane coupling agent. In the formation of the pressure-sensitive adhesive layer, a suitable pressure-sensitive adhesive having a hydroxyl group can be used, and the kind thereof is not particularly limited. Examples of the pressure-sensitive adhesive include rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, polyvinyl alcohol-based pressure-sensitive adhesives, polyvinyl pyrrolidone-based pressure-sensitive adhesives, polyacrylamide-based pressure-sensitive adhesives, and cellulose-based pressure-sensitive adhesives. Various base polymers may be used depending on the binders.

In the pressure-sensitive adhesive layer or the pressure-sensitive adhesive composition (solid content), the proportion of the base polymer having a hydroxyl group is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight or more.

Among these pressure-sensitive adhesives, those excellent in optical transparency, exhibiting suitable adhesive properties such as wettability, cohesiveness and adhesiveness, and excellent in weather resistance, heat resistance and the like are preferably used. As the adhesive exhibiting such characteristics, an acrylic adhesive is preferably used. As the base polymer of the acrylic adhesive, a (meth) acrylic polymer can be used. The (meth) acrylic polymer generally contains a monomer unit having an alkyl (meth) acrylate as a main component. The term (meth) acrylate means acrylate and/or methacrylate, and the same meaning is applied to (meth) acrylate of the present invention.

Examples of the alkyl (meth) acrylate constituting the main skeleton of the (meth) acrylic polymer include linear or branched alkyl (meth) acrylates having an alkyl group of 1 to 18 carbon atoms. For example, as the above alkyl group, there may be exemplified a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group, a cyclohexyl group, a heptyl group, a 2-ethylhexyl group, an isooctyl group, a nonyl group, a decyl group, an isodecyl group, a dodecyl group, an isomyristyl group, a lauryl group, a tridecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group and the like, which may be used alone or in combination. The average number of carbon atoms of these alkyl groups is preferably 3 to 9.

The (meth) acrylic polymer used in the present invention preferably contains a hydroxyl group-containing monomer as a monomer unit. The hydroxyl group-containing monomer has a polymerizable functional group containing an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and has a hydroxyl group. Specific examples of the hydroxyl group-containing monomer include: hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methacrylate.

The (meth) acrylic polymer is composed mainly of an alkyl (meth) acrylate in terms of weight ratio in the total constituent monomers, and the proportion of the hydroxyl group-containing monomer in the (meth) acrylic polymer is preferably 0.01 to 15%, more preferably 0.03 to 10%, and still more preferably 0.05 to 7% in terms of weight ratio in the total constituent monomers.

In addition, in order to improve adhesiveness and heat resistance, 1 or more kinds of comonomers having a polymerizable functional group containing an unsaturated double bond such as a (meth) acryloyl group or a vinyl group may be introduced into the (meth) acrylic polymer by copolymerization.

Examples of the comonomer include: carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as styrenesulfonic acid, allylsulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxynaphthalenesulfonic acid; phosphoric acid group-containing monomers such as 2-hydroxyethyl acrylate phosphate, and the like.

Examples of the monomer for modification include: (N-substituted) amide monomers such as (meth) acrylamide, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide and N-methylol propane (meth) acrylamide; alkylaminoalkyl (meth) acrylate monomers such as aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; alkoxyalkyl (meth) acrylate monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; succinimide monomers such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexylene succinimide, N- (meth) acryloyl-8-oxyoctylene succinimide, and N-acryloylmorpholine; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide; and itaconimide monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexyl itaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide.

Further, as the modifying monomer, vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methyl vinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyl oxazole, vinyl morpholine, N-vinylcarboxamides, styrene, α -methylstyrene, and N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; glycol acrylate monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypropylene glycol (meth) acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluoro (meth) acrylate, silicone (meth) acrylate, and 2-methoxyethyl acrylate. Further, isoprene, butadiene, isobutylene, vinyl ether and the like can be mentioned.

Examples of the copolymerizable monomer other than those described above include silane-based monomers containing a silicon atom. Examples of the silane monomer include: 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloxydecyltrimethoxysilane, 10-acryloxydecyltrimethoxysilane, 10-methacryloxydecyltriethoxysilane, 10-acryloxydecyltriethoxysilane, and the like.

Polyfunctional monomers having 2 or more unsaturated double bonds such as (meth) acryloyl groups and vinyl groups, such as esters of (meth) acrylic acid with polyhydric alcohols, e.g., tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, bisphenol a glycidyl ether di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone-modified dipentaerythritol hexa (meth) acrylate; polyester (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates and the like obtained by adding 2 or more unsaturated double bonds such as a (meth) acryloyl group and a vinyl group, which are functional groups similar to those of the monomer component, to the backbone of polyester, epoxy, urethane and the like.

The proportion of the above-mentioned comonomer (excluding the hydroxyl group-containing monomer) in the (meth) acrylic polymer is not particularly limited, and is about 0 to 20% by weight, preferably about 0.1 to 15% by weight, and more preferably about 0.1 to 10% by weight of the total constituent monomers.

Among these comonomers (excluding hydroxyl group-containing monomers), carboxyl group-containing monomers are preferably used from the viewpoint of adhesion and durability. When the carboxyl group-containing monomer is contained as a comonomer, the proportion thereof is preferably 0.05 to 10% by weight, more preferably 0.1 to 8% by weight, and still more preferably 0.2 to 6% by weight.

The (meth) acrylic polymer of the present invention is usually a (meth) acrylic polymer having a weight average molecular weight in the range of 50 to 300 ten thousand. In view of durability, particularly heat resistance, the (meth) acrylic polymer having a weight average molecular weight of 70 to 270 ten thousand is preferably used, and the weight average molecular weight of 80 to 250 ten thousand is more preferably used. When the weight average molecular weight is less than 50 ten thousand, it is not preferable from the viewpoint of heat resistance. When the weight average molecular weight is more than 300 ten thousand, a large amount of a diluting solvent is required to adjust the viscosity for coating, which is not preferable because the cost increases. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

The known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations can be appropriately selected for the production of such a (meth) acrylic polymer. The (meth) acrylic polymer to be obtained may be in any form such as a random copolymer, a block copolymer, or a graft copolymer.

The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and may be appropriately selected and used. The weight average molecular weight of the (meth) acrylic polymer can be controlled by the amount of the polymerization initiator, the amount of the chain transfer agent used, and the reaction conditions, and the amount of the chain transfer agent used can be adjusted to an appropriate amount depending on the type of the (meth) acrylic polymer.

Further, the adhesive composition of the present invention contains a mercapto group-containing silane coupling agent in addition to the above-described base polymer having a hydroxyl group (e.g., (meth) acrylic polymer). Examples of the mercapto group-containing silane coupling agent include compounds having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldiethoxysilane, β -mercaptomethylphenylethyltrimethoxysilane, mercaptomethyltrimethoxysilane, 6-mercaptohexyltrimethoxysilane, and 10-mercaptodecyltrimethoxysilane.

The mercapto group-containing silane coupling agent is preferably an oligomer-type mercapto group-containing silane coupling agent having 2 or more alkoxysilyl groups in the molecule. Specific examples thereof include X-41-1805, X-41-1818 and X-41-1810 manufactured by shin-Etsu chemical Co. These mercapto group-containing silane coupling agents are preferred because they are less volatile and have a plurality of alkoxysilyl groups, thereby effectively improving durability. The oligomer type herein means a polymer of about 2 to less than 100 units of monomers, and the weight average molecular weight of the oligomer type silane coupling agent is preferably about 300 to 30000.

The number of alkoxysilyl groups of the oligomer-type mercapto group-containing silane coupling agent is not limited as long as it is 2 or more in the molecule. In the silane coupling agent, the amount of the alkoxy group in the oligomer-type mercapto group-containing silane coupling agent is preferably 10 to 60% by weight, more preferably 20 to 50% by weight, and still more preferably 20 to 40% by weight.

The kind of the alkoxy group is not limited, and examples thereof include: an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, or a hexyloxy group. Among these, methoxy group and ethoxy group are preferable, and methoxy group is more preferable. In addition, it is also preferable that both methoxy and ethoxy groups be contained in one molecule.

The content of the mercapto group in the mercapto group-containing silane coupling agent, for example, in the case of a mercapto group (-SH), is preferably 1000g/mol or less, more preferably 800g/mol or less, and still more preferably 500g/mol or less in terms of the mercapto group equivalent. The lower limit of the mercapto equivalent is not particularly limited, but is preferably 200g/mol or more, for example.

The mercapto group-containing silane coupling agent may be used alone or in combination of 2 or more, and the total content thereof is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, even more preferably 0.02 to 2 parts by weight, and particularly preferably 0.05 to 1 part by weight, based on 100 parts by weight of the hydroxyl group-containing base polymer (e.g., (meth) acrylic polymer).

Further, a silane coupling agent other than the mercapto group-containing silane coupling agent may be added to the pressure-sensitive adhesive composition of the present invention. Examples of other coupling agents include: amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1, 3-dimethylbutylidene) propylamine and N-phenyl-gamma-aminopropyltrimethoxysilane, (meth) acryloyl group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane, and isocyanato group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane.

The silane coupling agent other than the mercapto group-containing silane coupling agent may be added within a range not impairing the effects of the present invention, and the amount of the silane coupling agent used is not particularly limited, and for example, from the viewpoint of adhesion to an adherend, the silane coupling agent may be used within a range of 3 parts by weight or less, more preferably 2 parts by weight or less, and still more preferably 1 part by weight or less, relative to 100 parts by weight of the adhesive composition. By using a silane coupling agent other than mercapto groups, adhesion can be improved. However, since a silane coupling agent other than mercapto groups can also impart reworking (reworking) properties, if the amount of addition is large, adhesion tends to deteriorate.

In addition, the adhesive composition of the present invention may contain a crosslinking agent. The crosslinking agent can be used alone in 1, in addition to the mixture of more than 2. The content of the total crosslinking agent is preferably 2 parts by weight or less, more preferably 1.5 parts by weight or less, and further preferably 1 part by weight or less, based on 100 parts by weight of the hydroxyl group-containing base polymer.

In the adhesive composition of the present invention, it is preferable that the crosslinking agent (b) which does not react with a hydroxyl group is contained as the crosslinking agent. The crosslinking agent (b) which does not react with a hydroxyl group may be used in combination with an isocyanate-based crosslinking agent, but a mode in which the isocyanate-based crosslinking agent is not contained is preferable. In the absence of an isocyanate-based crosslinking agent, the adhesive composition of the present invention eliminates operational problems associated with pot life. The crosslinking agent (b) which does not react with a hydroxyl group can produce a hard adhesive layer having a gel fraction of 80% or more from the initial stage of forming the adhesive layer without aging particularly for achieving a given gel fraction after forming the adhesive layer. Further, since the pressure-sensitive adhesive layer is crosslinked by the crosslinking agent (b) which does not react with a hydroxyl group, it is considered that the hydroxyl group of the base polymer can effectively react with a silanol group of the mercapto group-containing silane coupling agent, and the gel fraction of the pressure-sensitive adhesive layer can be hardened to 80% or more in the initial stage.

The crosslinking agent (b) may be used alone in 1 kind, or may be used in a mixture of 2 or more kinds, and the total content of the crosslinking agent (b) is preferably 0.01 to 2 parts by weight, more preferably 0.04 to 1.5 parts by weight, further preferably 0.05 to 1 part by weight, and further preferably 0.4 to 0.6 part by weight, based on 100 parts by weight of the hydroxyl group-containing base polymer. For the purpose of adjusting processability, reworkability, crosslinking stability, peelability and the like, it can be appropriately selected within the above range.

As the crosslinking agent (b), a peroxide can be preferably used

The amount of peroxide decomposition remaining after the reaction treatment can be measured, for example, by HPLC (high performance liquid chromatography).

More specifically, for example, about 0.2g of each of the reaction-treated adhesive compositions was taken out, immersed in 10ml of ethyl acetate, extracted by shaking at 120rpm for 3 hours at 25 ℃ using a shaker, and then left to stand at room temperature for 3 days. Subsequently, 10ml of acetonitrile was added, the mixture was shaken at 120rpm for 30 minutes at 25 ℃ and filtered by a membrane filter (0.45 μm) to obtain an extract, and about 10 μ l of the obtained extract was injected into HPLC to analyze the mixture, whereby the amount of peroxide after the reaction treatment was obtained.

The peroxide may be suitably used as long as it is a peroxide which generates radical active species by heating or light irradiation to crosslink the base polymer of the pressure-sensitive adhesive composition, but in view of workability and stability, a peroxide having a 1-minute half-life temperature of 80 to 160 ℃ is preferably used, and a peroxide having a 1-minute half-life temperature of 90 to 140 ℃ is more preferably used.

Examples of peroxides that can be used include: di (2-ethylhexyl) peroxydicarbonate (1-minute half-life temperature: 90.6 ℃ C.), di (4-tert-butylcyclohexyl) peroxydicarbonate (1-minute half-life temperature: 92.1 ℃ C.), di-sec-butyl peroxydicarbonate (1-minute half-life temperature: 92.4 ℃ C.), tert-butyl peroxyneodecanoate (1-minute half-life temperature: 103.5 ℃ C.), tert-hexyl peroxypivalate (1-minute half-life temperature: 109.1 ℃ C.), tert-butyl peroxypivalate (1-minute half-life temperature: 110.3 ℃ C.), dilauroyl peroxide (1-minute half-life temperature: 116.4 ℃ C.), di-n-octanoyl peroxide (1-minute half-life temperature: 117.4 ℃ C.), 1,3, 3-tetramethylbutyl peroxy-2-ethylhexanoate (1-minute half-life temperature: 124.3 ℃ C.), di (4-methylbenzoyl) peroxide (1-minute half-life temperature: 128.2 ℃ C.), and, Dibenzoyl peroxide (1 minute half-life temperature: 130.0 ℃ C.), t-butyl peroxyisobutyrate (1 minute half-life temperature: 136.1 ℃ C.), 1-bis (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ℃ C.), and the like. Among them, bis (4-t-butylcyclohexyl) peroxydicarbonate (1-minute half-life temperature: 92.1 ℃ C.), dilauroyl peroxide (1-minute half-life temperature: 116.4 ℃ C.), dibenzoyl peroxide (1-minute half-life temperature: 130.0 ℃ C.) and the like are particularly preferably used from the viewpoint of excellent crosslinking reaction efficiency.

The half-life of the peroxide is an index indicating the decomposition rate of the peroxide, and means the time until the residual amount of the peroxide reaches half. The decomposition temperature for obtaining the half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in a product catalog of a manufacturer or the like, for example, in "catalog of organic peroxide products 9 th edition (5/2003) of japan grease corporation or the like.

As the crosslinking agent other than the crosslinking agent (b), an organic crosslinking agent or a polyfunctional metal chelate compound can be used. Examples of the organic crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. The polyfunctional metal chelate compound is a metal chelate compound in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of the polyvalent metal atom include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti and the like. Examples of the atom in the organic compound to be covalently or coordinately bonded include an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound.

The amount of the crosslinking agent other than the crosslinking agent (b) is preferably controlled so that a hard pressure-sensitive adhesive layer having a gel fraction of 80% or more from the initial stage of forming the pressure-sensitive adhesive layer can be produced. For example, the crosslinking agent other than the crosslinking agent (b) may be used in an amount of 2 parts by weight or less based on 100 parts by weight of the adhesive composition, and may be contained in an amount of 1 part by weight or less, more preferably 0.5 part by weight or less. In particular, when an isocyanate-based crosslinking agent is used as a crosslinking agent other than the crosslinking agent (b), the amount of the isocyanate-based crosslinking agent is controlled within a range in which curing is not necessary. An isocyanate-based crosslinking agent is preferable in terms of securing the anchoring force between the adherend and the film or the like, and an isocyanate-based crosslinking agent is also preferable in terms of hardening the adhesive layer and suppressing the dimensional change of the polarizing film. Further, since a stronger anchoring force can be obtained, it is particularly preferable to use an isocyanate-based crosslinking agent in combination with the crosslinking agent (b) which does not react with a hydroxyl group.

the pressure-sensitive adhesive composition of the present invention may contain an alkali metal salt, a polyether-modified organosilicon compound, and other known additives, and for example, a polyether compound such as a polyalkylene glycol such as polypropylene glycol, a colorant, a powder such as a pigment, a dye, a surfactant, a plasticizer, a thickener, a surface lubricant, a leveling agent, a softener, an antioxidant, a light stabilizer, an ultraviolet absorber, a polymerization inhibitor, an inorganic filler or an organic filler, a metal powder, a particulate material, a foil material, and the like may be appropriately added depending on the application. In addition, a redox system in which a reducing agent is added may be used within a controllable range.

The pressure-sensitive adhesive layer is formed by the pressure-sensitive adhesive composition, but when the pressure-sensitive adhesive layer is formed, it is preferable to adjust the amount of the entire crosslinking agent to be added and to sufficiently consider the influence of the crosslinking temperature and the crosslinking time.

The crosslinking temperature and the crosslinking time can be adjusted according to the crosslinking agent used. The crosslinking treatment temperature is preferably 170 ℃ or lower.

The crosslinking treatment may be performed at a temperature at the time of the drying step of the pressure-sensitive adhesive layer, or a crosslinking treatment step may be separately provided after the drying step.

The crosslinking treatment time may be set in consideration of productivity and workability, but is usually about 0.2 to 20 minutes, preferably about 0.5 to 10 minutes.

As a method of forming the adhesive layer, it can be produced by, for example: a method in which the pressure-sensitive adhesive composition is applied to a separator or the like subjected to a peeling treatment, and then a polymerization solvent or the like is dried to remove a pressure-sensitive adhesive layer, followed by transfer to a anchor coat layer in the embodiment of fig. 1 and 2; or a method of forming an adhesive layer on a polarizing film by applying the adhesive composition to a tie coat layer and drying to remove a polymerization solvent or the like in the embodiment of fig. 1 and 2; and so on. In the case of applying the adhesive, one or more solvents other than the polymerization solvent may be added newly as appropriate.

As the separator subjected to the peeling treatment, a silicone release liner is preferably used. In the step of forming the pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive composition of the present invention to such a liner and drying the applied pressure-sensitive adhesive composition, a suitable method can be appropriately employed as a method for drying the pressure-sensitive adhesive composition according to the purpose. A method of drying the coating film by heating is preferably used. The heating and drying temperature is preferably 40 to 200 ℃, more preferably 50 to 180 ℃, and particularly preferably 70 to 170 ℃. By setting the heating temperature in the above range, an adhesive layer having excellent adhesive properties can be obtained.

The drying time may be suitably selected from a suitable time, preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

as a method for forming the adhesive layer, various methods can be used. Specific examples thereof include: roll coating, roll-and-lick coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, blade coating, air knife coating, curtain coating, lip coating, extrusion coating using a die coater, and the like.

The thickness of the adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, preferably 2 to 50 μm, more preferably 2 to 40 μm, and further preferably 5 to 35 μm.

In the case where the adhesive layer is exposed, the adhesive layer may be protected with a sheet (separator) subjected to a peeling treatment before use.

Examples of the constituent material of the separator include: plastic films such as polyethylene, polypropylene, polyethylene terephthalate and polyester films, porous materials such as paper, cloth and nonwoven fabrics, and suitable sheets such as nets, foamed sheets, metal foils and laminates thereof are preferably used from the viewpoint of excellent surface smoothness.

The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer, and examples thereof include: polyethylene films, polypropylene films, polybutylene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, ethylene-vinyl acetate copolymer films, and the like.

The thickness of the separator is usually 5 to 200 μm, preferably about 5 to 100 μm. The separator may be subjected to mold release and antifouling treatment, or antistatic treatment such as coating type, mixing type, vapor deposition type, or the like, using a mold release agent of silicone type, fluorine-containing type, long chain alkyl type, or fatty acid amide type, silica powder, or the like, as necessary. In particular, by appropriately subjecting the surface of the separator to a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine-containing treatment, the releasability from the pressure-sensitive adhesive layer can be further improved.

The sheet subjected to the peeling treatment used in the production of the above-mentioned polarizing film with an adhesive layer can be used as it is as a separator for a polarizing film with an adhesive layer, and can be omitted from the viewpoint of the process.

< surface protective film >

A surface protective film may be disposed on the polarizing film with the adhesive layer. The surface protective film generally has a base film and an adhesive layer, and protects the polarizer by the adhesive layer.

The base film of the surface protective film may be selected from materials having isotropy or near isotropy from the viewpoint of inspection properties, manageability, and the like. Examples of the film material include transparent polymers such as polyester resins such as polyethylene terephthalate films, cellulose resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and acrylic resins. Of these, polyester-based resins are preferred. The substrate film may be a laminate of 1 or 2 or more kinds of film materials, or a stretched product of the above film. The thickness of the base film is usually 500 μm or less, preferably 10 to 200 μm.

As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer of the surface protective film, a pressure-sensitive adhesive containing a polymer such as a (meth) acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-containing polymer, or a rubber as a base polymer can be suitably selected. From the viewpoint of transparency, weather resistance, heat resistance and the like, an acrylic adhesive containing an acrylic polymer as a base polymer is preferred. The thickness (dry film thickness) of the pressure-sensitive adhesive layer is determined depending on the required adhesive strength, and is usually about 1 to 100 μm, preferably 5 to 50 μm.

In the surface protective film, a release treated layer may be provided on the surface of the base film opposite to the surface on which the pressure-sensitive adhesive layer is provided, using a low-adhesion material subjected to a silicone treatment, a long-chain alkyl treatment, a fluorine treatment, or the like.

< other optical layers >

The polarizing film with an adhesive layer of the present invention may be used in the form of an optical film formed by laminating it with another optical film in actual use. The optical layer is not particularly limited, and optical layers that are sometimes used in the formation of liquid crystal display devices and the like, such as 1-layer or 2-layer or more reflective plates, semi-transmissive plates, retardation plates (including 1/2 wave plates, 1/4 wave plates, and the like), and viewing angle compensation films, can be used. In particular, a reflective polarizing film or a semi-transmissive polarizing film obtained by further laminating a reflective plate or a semi-transmissive reflective plate on the polarizing film with an adhesive layer of the present invention, an elliptical polarizing film or a circular polarizing film obtained by further laminating a phase difference plate on the polarizing film, a wide-angle polarizing film obtained by further laminating a viewing angle compensation film on the polarizing film, or a polarizing film obtained by further laminating a brightness enhancement film on the polarizing film is preferable.

The optical film obtained by laminating the optical layer on the polarizing film with an adhesive layer can be formed by sequentially laminating the respective layers in the production process of a liquid crystal display device or the like, but when the optical film is prepared by laminating the layers in advance, the following advantages are obtained: the quality stability, the assembly operation and the like are excellent, and the manufacturing process of a liquid crystal display device and the like can be improved. The laminate may be bonded by a suitable bonding method such as an adhesive layer. In the case of bonding the above-described polarizing film with an adhesive layer and other optical films, the optical axes thereof may be arranged at an appropriate angle depending on the desired retardation characteristics and the like.

The polarizing film or optical film with an adhesive layer of the present invention can be preferably used for formation of various devices such as a liquid crystal display device. The liquid crystal display device can be formed in a conventional manner. That is, the liquid crystal display device can be generally formed by appropriately assembling a liquid crystal cell, a polarizing film or an optical film with an adhesive layer, and if necessary, a component such as an illumination system, and then incorporating a driving circuit, and the like. As the liquid crystal cell, any type of liquid crystal cell such as IPS type, VA type, or the like can be used.

A suitable liquid crystal display device such as a liquid crystal display device in which a polarizing film or an optical film with a pressure-sensitive adhesive layer is disposed on one side or both sides of a liquid crystal cell, or a device using a backlight or a reflector in a lighting system can be formed. In this case, the polarizing film or optical film with an adhesive layer of the present invention may be disposed on one side or both sides of the liquid crystal cell. In the case where the polarizing film or the optical film with an adhesive layer is provided on both sides, they may be the same or different. In forming a liquid crystal display device, appropriate members such as a diffuser plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffuser plate, and a backlight may be disposed in appropriate positions, for example, in 1 layer or 2 layers or more.

Examples

The present invention will be described below with reference to examples, but the present invention is not limited to the examples shown below. In each example, parts and% are on a weight basis. The following conditions of standing at room temperature, which are not particularly specified, are 23 ℃ and 65% RH.

< (meth) acrylic Polymer weight average molecular weight measurement

The weight average molecular weight of the (meth) acrylic polymer was measured by GPC (gel permeation chromatography).

An analysis device: HLC-8120GPC, manufactured by Tosoh corporation

Column: g7000HXL + GMHXL manufactured by Tosoh corporation

Column size: each column was 7.8 mm. phi. times.30 cm, total 90cm

Column temperature: 40 deg.C

Flow rate: 0.8ml/min

Injection amount: 100 μ l

Eluent: tetrahydrofuran (THF)

The detector: differential Refractometer (RI)

Standard sample: polystyrene

< making of polarizer >

A laminate was produced by subjecting one surface of a substrate to corona treatment, which was an amorphous film (thickness: 100 μm) of polyethylene isophthalate-co-terephthalate (IPA-co-PET) having a water absorption rate of 0.75% and a Tg of 75 ℃, to a corona treatment, applying an aqueous solution containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl-modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon synthetic chemical industries, Ltd., trade name "GOHSIMEFERZ 200") at a ratio of 9:1 to the corona treatment surface at 25 ℃ and drying the aqueous solution to form a PVA-based resin layer having a thickness of 11 μm.

The obtained laminate was subjected to free-end uniaxial stretching (auxiliary stretching treatment in a gas atmosphere) in an oven at 120 ℃ between rolls having different peripheral speeds to 2.0 times in the longitudinal direction (longitudinal direction).

Next, the laminate was immersed in an insolubilization bath (an aqueous boric acid solution prepared by adding 4 parts by weight of boric acid to 100 parts by weight of water) at a liquid temperature of 30 ℃ for 30 seconds (insolubilization treatment).

Then, the polarizing plate was immersed in a dyeing bath at a liquid temperature of 30 ℃ for a predetermined period of time while adjusting the iodine concentration, so that the polarizing plate had a predetermined transmittance. In this example, the substrate was immersed in an aqueous iodine solution containing 0.2 parts by weight of iodine and 1.0 part by weight of potassium iodide per 100 parts by weight of water for 60 seconds (dyeing treatment).

Next, the substrate was immersed in a crosslinking bath (aqueous boric acid solution prepared by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid to 100 parts by weight of water) at a liquid temperature of 30 ℃ for 30 seconds (crosslinking treatment).

Then, the laminate was immersed in an aqueous boric acid solution (an aqueous solution prepared by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide per 100 parts by weight of water) at a liquid temperature of 70 ℃.

Then, the laminate was immersed in a cleaning bath (aqueous solution containing 4 parts by weight of potassium iodide per 100 parts by weight of water) at a liquid temperature of 30 ℃ (cleaning treatment).

An optical film laminate including a polarizer having a thickness of 5 μm was obtained by the above-described procedure.

(preparation of protective film)

Protecting the film: the easily adhesive surface of a (meth) acrylate resin film having a lactone ring structure and having a thickness of 40 μm was subjected to corona treatment and used.

(preparation of adhesive for protective film)

An ultraviolet-curable adhesive was prepared by mixing 40 parts by weight of N-hydroxyethyl acrylamide (HEAA), 60 parts by weight of acryloyl morpholine (ACMO), and 3 parts by weight of a photoinitiator IRGACURE 819 (BASF corporation).

< production of Single-sided protective polarizing film >

The above-mentioned ultraviolet-curable adhesive was applied to the surface of the polarizing film of the optical film laminate so that the thickness of the cured adhesive layer was 0.5 μm, and the protective film was bonded thereto, and then the adhesive was cured by irradiation with ultraviolet rays as an active energy ray. The ultraviolet irradiation uses a gallium-sealed metal halide lamp, an irradiation device: lighthorn 10 manufactured by Fusion UV Systems, Inc, valve: v valve, peak illuminance: 1600mW/cm2, a cumulative dose of 1000/mJ/cm2 (wavelength 380-440 nm), and the illuminance of ultraviolet light were measured using Sola-Check system manufactured by Solatell corporation. Next, the amorphous PET substrate was peeled off, and a single-side protective polarizing film a using a thin polarizing film was produced. The optical properties of the resulting single-sided protective polarizing film were: the transmittance is 42.8 percent, and the polarization degree is 99.99 percent.

< tackifying coat-forming material: polyvinyl alcohol resin composition

An aqueous solution having a solid content of 4% by weight was prepared by dissolving 100 parts of a polyvinyl alcohol resin having a polymerization degree of 2500 and a saponification degree of 99.7 mol% and 5 parts of methylolmelamine (trade name "water sol: S-695", manufactured by DIC Co., Ltd.) in pure water.

< preparation of acrylic Polymer >

A4-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube and a cooler was charged with a monomer mixture containing 99 parts of butyl acrylate and 1 part of 2-hydroxyethyl acrylate. Further, 2' -azobisisobutyronitrile as a polymerization initiator was added together with ethyl acetate in an amount of 0.1 part per 100 parts of the monomer mixture (solid content), nitrogen substitution was performed by introducing nitrogen gas with slow stirring, and then polymerization was performed for 7 hours while maintaining the liquid temperature in the flask at about 60 ℃. Then, ethyl acetate was added to the obtained reaction solution to adjust the solid content concentration to 30%, thereby preparing a solution of an acrylic polymer having a weight average molecular weight of 140 ten thousand.

(preparation of adhesive composition)

An acrylic pressure-sensitive adhesive solution was prepared by mixing 0.2 part of an oligomer-type mercapto group-containing silane coupling agent (alkoxy group amount: 30% by weight, mercapto group equivalent: 450g/mol, X-41-1810 available from shin-Etsu chemical Co., Ltd.) and 0.42 part of dibenzoyl peroxide per 100 parts of the solid content of the acrylic polymer solution.

(formation of adhesive layer)

Subsequently, the acrylic pressure-sensitive adhesive solution was uniformly applied to the surface of a polyethylene terephthalate film (separator) treated with a silicone-based release agent, and the film was dried in an air-circulating oven at 155 ℃ for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 20 μm on the surface of the separator.

Example 1

< making a one-sided protective polarizing film with a tie coat >

The polyvinyl alcohol resin composition adjusted to 25 ℃ was applied to one surface (polarizing mirror surface not provided with a protective film) of the polarizing film (polarizing mirror) of the one-side protective polarizing film by a wire bar coater so that the thickness after drying was 1 μm, and then hot air drying was performed at 90 ℃ for 20 seconds to prepare a one-side protective polarizing film with a tie coat layer.

< production of polarizing film with adhesive layer >

Next, the pressure-sensitive adhesive layer formed on the release-treated surface of the release sheet (separator) was bonded to the anchor coat layer formed on the one-side protective polarizing film, thereby producing a polarizing film with a pressure-sensitive adhesive layer.

Examples 2 to 11 and comparative examples 1 to 6

A one-side protective polarizing film with a tie coat layer and a polarizing film with an adhesive layer were produced in the same manner as in example 1, except that the kind of the aqueous resin blended in the tie coat layer in example 1, the blending amount of methylolmelamine (the blending ratio is a value based on 100 parts of the aqueous resin), the kind of the silane coupling agent and the crosslinking agent in the adhesive composition, and the blending amount (the blending ratio is a value based on 100 parts of the acrylic polymer) were changed as shown in table 1.

The polarizing films with adhesive layers obtained in the above examples and comparative examples were evaluated as follows. The results are shown in Table 1.

< determination of initial gel fraction >

About 0.1g of the pressure-sensitive adhesive layer formed on the release-treated surface of the separator within 1 minute after the production was scraped off, and this was defined as sample 1. The above sample 1 was wrapped in a teflon (registered trademark) film (trade name "NTF 1122", manufactured by ritong electric corporation) having a diameter of 0.2 μm, and then bound with a string to obtain a sample 2. The weight of sample 2 before being subjected to the following test was measured and defined as weight a. The weight a is the total weight of sample 1 (adhesive layer), teflon (registered trademark) film, and string. The total weight of the teflon (registered trademark) film and the string was defined as weight B. Next, the sample 2 was placed in a 50ml container filled with ethyl acetate and allowed to stand at 23 ℃ for 1 week. Then, sample 2 was taken out of the container, dried in a dryer at 130 ℃ for 2 hours to remove ethyl acetate, and then the weight of sample 2 was measured. The weight of sample 2 supplied after the above test was measured and defined as weight C. Then, the gel fraction was calculated from the following formula.

Gel fraction (% by weight) — (C-B)/(a-B) × 100

The initial gel fraction of the adhesive layer is preferably 80% or more. The low gel fraction causes problems such as the coating mark easily remaining.

< anchoring force >

The polarizing films with adhesive layers obtained in examples and comparative examples were cut into 25mm × 150mm pieces, and the adhesive layer surfaces were bonded to the deposition surface of a vapor-deposited film formed by depositing indium-tin oxide on the surface of a polyethylene terephthalate film having a thickness of 50 μm. Then, the edge of the polyethylene terephthalate film was peeled off by hand, and after confirming that the pressure-sensitive adhesive layer was adhered to the polyethylene terephthalate film side, the stress (N/25mm) at the time of peeling in the 180 ℃ direction at a speed of 300 mm/min was measured using a tensile tester AG-1 manufactured by Shimadzu corporation.

When the anchoring force is 15N/25mm or more, there is no residual glue during the re-operation, and no glue shortage or glue falling off during the processing, which is a good condition. The failure state at the time of the above-mentioned peeling is represented by "cohesive failure (failure of the anchor coat layer or the pressure-sensitive adhesive layer)" or "interfacial peeling (peeling at the interface between the anchor coat layer and the pressure-sensitive adhesive layer)". In comparative example 7, the anchoring force was measured after 48 hours of aging because only an isocyanate-based crosslinking agent was used as the crosslinking agent of the pressure-sensitive adhesive layer. The examples and other comparative examples are values measured within 24 hours (for aging) after the production of the polarizing film with an adhesive layer.

In table 1, peroxides are under the trade name: nyper BMT 40SV, benzoyl peroxide, manufactured by Nippon oil and fat Co., Ltd.;

Isocyanates are trade names: takenate D110N, trimethylolpropane adduct of xylylenediisocyanate, manufactured by Mitsui chemical Co., Ltd.;

X-41-1810: oligomer type mercapto group-containing silane coupling agent, alkoxy group amount: 30% by weight, mercapto equivalent: 450g/mol, manufactured by shin-Etsu chemical industries, Ltd;

KBM-802: a monomeric mercapto group-containing silane coupling agent manufactured by shin-Etsu chemical industries, Ltd;

KBM-803: a monomeric mercapto group-containing silane coupling agent manufactured by shin-Etsu chemical industries, Ltd;

X-41-1056: oligomer-type epoxy group containing silane coupling agent, alkoxy group amount: 17% by weight, epoxy equivalent: 280g/mol, manufactured by shin Etsu chemical Co., Ltd.

The crosslinking agent of example 10 is a combination of an isocyanate-based crosslinking agent and a peroxide crosslinking agent.

Oxazoline group-containing polymer: EPOCROS WS-700 (manufactured by Nippon catalyst Co., Ltd.);

Polyurethane resin: TaKELAC W-6020 (available from Mitsui chemical polyurethane Co., Ltd.);

Epoxy resin: celloxide 2021P (manufactured by Daiiluo Co., Ltd.).

Claims (18)

1. A polarizing film with an adhesive layer, comprising a polarizer, an anchor coat layer and an adhesive layer in this order,

The anchor coat layer is formed from an aqueous resin composition containing an aqueous resin and a compound (a) having at least one primary alcohol capable of reacting with a hydroxyl group at the molecular terminal,

The adhesive layer is formed from an adhesive composition comprising: a base polymer having a hydroxyl group, and a mercapto group-containing silane coupling agent.

2. The polarizing film with an adhesive layer according to claim 1, wherein the aqueous resin is at least one selected from the group consisting of polyvinyl alcohol resins, polyurethane resins, epoxy resins, and oxazoline group-containing polymers.

3. The adhesive layer-equipped polarizing film according to claim 2, wherein the aqueous resin is a polyvinyl alcohol-based resin.

4. The polarizing film with an adhesive layer according to claim 3, wherein the polyvinyl alcohol-based resin has a saponification degree of 96 mol% or more and an average polymerization degree of 2000 or more.

5. The adhesive layer-equipped polarizing film according to claim 1, wherein the aqueous resin composition comprises 0.2 to 20 parts by weight of the compound (a) per 100 parts by weight of the aqueous resin.

6. The polarizing film with an adhesive layer according to claim 1, wherein the thickness of the anchor coat layer is 0.05 μm or more and 6 μm or less.

7. the adhesive layer-equipped polarizing film according to claim 1, wherein the base polymer having a hydroxyl group is a (meth) acrylic polymer having a hydroxyl group.

8. The polarizing film with an adhesive layer according to claim 1, wherein the adhesive composition comprises 0.01 to 5 parts by weight of the mercapto group-containing silane coupling agent with respect to 100 parts by weight of the base polymer having hydroxyl groups.

9. The adhesive layer-equipped polarizing film according to claim 1, wherein the adhesive composition contains a crosslinking agent.

10. The adhesive layer-equipped polarizing film according to claim 9, wherein the crosslinking agent contains a crosslinking agent (b) that does not react with a hydroxyl group.

11. The adhesive layer-equipped polarizing film according to claim 10, wherein the crosslinking agent (b) that does not react with a hydroxyl group is a peroxide.

12. The adhesive layer-equipped polarizing film according to claim 10, wherein the crosslinking agent (b) that does not react with a hydroxyl group is contained in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of the base polymer having a hydroxyl group.

13. The adhesive layer-equipped polarizing film according to claim 1, wherein the polarizer has a thickness of 15 μm or less.

14. The adhesive layer-equipped polarizing film according to claim 1, wherein the polarizer is configured such that optical properties represented by a monomer transmittance T and a polarization degree P satisfy the following conditions,

P > - (100.929T-42.4-1) x 100, wherein T < 42.3, and

P is more than or equal to 99.9, wherein T is more than or equal to 42.3.

15. The adhesive layer-attached polarizing film according to any one of claims 1 to 14, wherein the polarizer has a protective film on at least one side thereof.

16. The adhesive layer-equipped polarizing film according to claim 1, wherein a separator is laminated on the adhesive layer.

17. A method for producing a polarizing film with an adhesive layer according to any one of claims 1 to 16, comprising:

A step of forming an anchor coat layer by applying an aqueous resin composition containing an aqueous resin and a compound (a) having at least one primary alcohol capable of reacting with a hydroxyl group at a molecular end, onto a polarizer and then drying the aqueous resin composition; and

forming a pressure-sensitive adhesive layer on the anchor coat layer from a pressure-sensitive adhesive composition containing: a base polymer having a hydroxyl group, and a mercapto group-containing silane coupling agent.

18. An image display device having the adhesive layer-equipped polarizing film according to any one of claims 1 to 16.