KR20100089779A - Polarizer outside protection film, polarizing plate and liquid crystal display element - Google Patents

Abstract

PURPOSE: A polarized light device exterior protection film, a polarizer and a liquid crystal display device are provided to improve intensity and the handling of a polarizing plate by comprising a polarized light device exterior protection film. CONSTITUTION: A polarized light device exterior protection film(1) has a base layer(2) of transparent plastics, and a cellulose esterification surface processing layer(3). The base material layer is comprised with transparent plastics. The cellulose esterification surface processing layer is formed in the inside of the base material layer. The cellulose esterification surface processing layer is formed by contacting the surface treating agent containing cellulose ester and solvent in the inner surface of the base material layer. A primer layer is formed between the base material layer and the cellulose esterification surface processing layer.

Description

POLARIZER OUTSIDE PROTECTION FILM, POLARIZING PLATE AND LIQUID CRYSTAL DISPLAY ELEMENT}

The present invention relates to a polarizing plate having a polarizer outer protective film, a polarizer outer protective film, and a liquid crystal display device having a polarizing plate.

In recent years, liquid crystal displays (LCDs) have been widely used in place of CRT because they are thin, lightweight, and have low power consumption. Background Art [0002] The field of use of liquid crystal display devices has been extended from small products such as conventional electronic calculators and watches to large products such as automobile instruments, PC monitors, and televisions.

As illustrated in FIG. 6, a general liquid crystal display element 21 disposed in a liquid crystal display device includes a liquid crystal cell in which a liquid crystal layer 27 is sandwiched by a double-sided transparent medium layer 26 (for example, glass). 25 and a polarizing plate 22 having a protective film 23 for a polarizing plate attached to both surfaces of a polarizer 24 having polarizing ability, and the liquid crystal cell 25 is a polarizing plate 22 through an adhesive layer 28. It has a structure pinched from above and below. In this manner, the polarizer 24 is protected by the polarizer protective film 23 from the viewpoint of improving the strength and facilitating handling.

Generally as a material of a polarizer, polyvinyl alcohol (PVA) which is a hydrophilic resin can be used, The uniaxial stretching of a PVA film, dyeing with iodine or a dichroic dye, or extending | stretching after extending, and then boron compound is carried out. The polarizer is formed by crosslinking with. Moreover, as a polarizer protective film, triacetyl cellulose (TAC) is generally required from the point which optically transparent and small birefringence, smooth surface, excellent adhesiveness with the polarizer which consists of PVA, etc. are calculated | required. ) Is used. Triacetylcellulose is adhered to a polarizer composed of polyvinyl alcohol which is a hydrophilic resin after saponification treatment (the ester group is converted to a hydroxyl group which is a hydrophilic group) by alkali. As a technique for improving the various required characteristics of the above-described triacetyl cellulose, for example, formation of a predetermined resin layer into the triacetyl cellulose layer (Japanese Patent Laid-Open No. 9-113728, Japanese Patent Laid-Open No. 9-281333) ) Is proposed. By the way, since triacetyl cellulose is expensive, the development of an inexpensive alternative material having the same properties is required.

As the polarizer protective film disposed on the inner surface side of the liquid crystal display element (near from the liquid crystal cell), since it is particularly required to have a small birefringence (which is non-orientated), a suitable substitute material for developing triacetylcellulose is Inconspicuous On the other hand, as a required characteristic of the polarizer protective film which is arrange | positioned at the outer surface side (the position of the uppermost layer and the lowermost layer 23 in FIG. 6) away from a liquid crystal cell, a position where transparency is more important than presence or absence of birefringence. Since it is given, development of alternative materials other than triacetyl cellulose is expected.

Examples of general-purpose resin materials having high transparency that can be substituted for triacetyl cellulose include acrylic resins, polycarbonate resins, polypropylene resins, cycloolefin resins, polyethylene terephthalate resins, and the like. However, since these resins do not have a hydrophilic group, there is a problem that the adhesiveness with polyvinyl alcohol, which is a hydrophilic resin constituting the polarizer, is excellent, and thus they cannot be used as a substitute material of triacetyl cellulose as it is. Therefore, development of the novel polarizer outer surface protective film for arrange | positioning on the outer surface side of the liquid crystal display element which has high transparency and became easy to adhere with the polarizer which consists of polyvinyl alcohol is desired.

Japanese Patent Application Laid-Open No. 9-113728 Japanese Patent Application Laid-Open No. 9-281333

This invention is made | formed in view of these problems, The novel polarizer outer surface protective film which has high transparency and is arrange | positioned at the outer surface side of the liquid crystal display element by which the easy adhesion process was performed to the polarizer which consists of polyvinyl alcohol, and It aims at providing to the polarizing plate provided with such a polarizer outer surface protective film, and a liquid crystal display element.

The invention made in order to solve the said subject,

As a polarizer outer surface protective film arrange | positioned at the outer surface side of a liquid crystal display element,

Base material layer made of transparent synthetic resin,

It is a polarizer outer surface protective film provided with the cellulose-esterified surface treatment layer formed in the inner surface side of this base material layer.

According to the said polarizer outer surface protective film, the high transparency requested | required as a film which protects the polarizer located in the outer surface side of a liquid crystal display element is obtained by using transparent synthetic resin as a constituent material of a base material layer. Moreover, the said polarizer outer surface protective film is laminated | stacked the cellulose-esterification surface treatment layer on the inner surface side of a base material layer so that adhesion | attachment with the polarizer which consists of polyvinyl alcohols, and with the polarizer which consists of polyvinyl alcohol which is hydrophilic resin Adhesion is dramatically improved. That is, by saponifying the cellulose-esterified surface treatment layer formed by such an easy adhesion process with alkali, the hydroxyl group which is hydrophilic arises, and adhesiveness with polyvinyl alcohol which is a hydrophilic resin improves effectively by this. In addition, in this specification, the "inner surface" means the liquid crystal cell side of a center in the liquid crystal display element which clamps a liquid crystal cell between a pair of polarizing plates, and the "outer surface" means the opposite side. In addition, a "cellulose esterification surface treatment layer" means the layer which has a cellulose ester in at least one part of surface by surface treatment, such as application | coating.

The cellulose-esterified surface treatment layer in the said polarizer outer surface protective film can be formed by making the inner surface of a base material layer contact the surface treating agent containing a cellulose ester and a solvent. By using the polarizer outer surface protective film provided with the cellulose-esterified surface treatment layer formed in this way, a polarizer and the base material layer made of transparent synthetic resin are strongly bonded through the cellulose-esterified surface treatment layer, and the peeling resistance between these layers is carried out. This is improved.

The synthetic resin which comprises a base material layer in the said polarizer outer surface protective film may be at least 1 sort (s) chosen from the group which consists of acrylic resin, polycarbonate resin, polypropylene resin, cycloolefin resin, and polyethylene terephthalate resin. By using these synthetic resins, while having high transparency, in order to protect a polarizer, the polarizer outer surface protective film which has moderate intensity | strength is obtained.

The cellulose ester used for the surface treatment of the base material layer made of transparent synthetic resin may be one or two or more selected from the group consisting of triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate. Each of these cellulose esters generates a hydroxyl group which is a hydrophilic group by saponifying with alkali, whereby the cellulose ester can be firmly adhered to a polarizer made of polyvinyl alcohol which is a hydrophilic resin.

It is preferable that the thickness of the surface treatment layer of the cellulose ester formed in the inner surface side of the base material layer made of transparent synthetic resin is 0.01 micrometer or more and 3 micrometers or less. By making the thickness of the surface treatment layer of cellulose ester more than 0.01 micrometer, the ease of adhesiveness of the polarizer which consists of polyvinyl alcohol is accelerated | stimulated. On the other hand, by making thickness of this surface treatment layer into 3 micrometers or less, a sufficiently thin polarizer outer surface protective film can be obtained and the increase of the thickness of a polarizing plate can be suppressed.

It is preferable that the said polarizer outer surface protective film further has a primer layer between a base material layer and a cellulose-esterified surface treatment layer.

It is preferable that the primer layer of a polarizer outer surface protective film is formed from aqueous latex. Since the primer layer formed from such an aqueous latex has chemical affinity with both the base material layer made of a transparent synthetic resin, and the cellulose-esterified surface treatment layer, it bonds between these layers stably, and peeling of a cellulose-esterified surface treatment layer is carried out. Is effectively prevented, and furthermore, easy adhesion treatment to the polarizer of the base material layer can be reliably performed.

When the primer layer of the said polarizer outer surface protective film is formed from aqueous latex, as this aqueous latex, (meth) acrylic acid, (meth) acrylic acid derivative, (meth) acrylamide, (meth) acrylamide derivative, vinyl ester, Polymers obtained from at least one unsaturated monomer selected from the group consisting of olefins, styrenes, crotonic acid esters, itaconic acid esters, fumaric acid esters, vinyl ketones, heterocyclic vinyl monomers and unsaturated nitriles Can be used. By using a primer layer formed from an aqueous latex containing these polymers, the bonding between the substrate layer and the cellulose esterified surface treatment layer through the primer layer is made stronger, and the peeling of the cellulose esterified surface treatment layer is reliably prevented. .

In the said polarizer outer surface protective film, it is preferable that the sum total thickness of a primer layer and a cellulose-esterified surface treatment layer is 0.02 micrometer or more and 4 micrometers or less. By making the total thickness of a primer layer and a cellulose-esterification surface treatment layer into 0.02 micrometer or more, the ease of adhesiveness of the polarizer which consists of polyvinyl alcohol is accelerated | stimulated. On the other hand, by making the total thickness of a primer layer and a cellulose-esterification surface treatment layer into 4 micrometers or less, a sufficiently thin polarizer outer surface protective film can be obtained and the increase of the thickness of a polarizing plate can be suppressed.

The said polarizer outer surface protective film may be equipped with the antireflection layer (for example, what is called an antiglare layer, an antireflection layer, and a low refractive index layer) laminated | stacked on the outer surface side of a base material layer, or a hard-coat layer. Moreover, when the polarizer outer surface protective film provided with an antireflection layer is arrange | positioned at the display surface side of a liquid crystal display element, it can exhibit antireflection function with protection of a polarizer. Moreover, when a polarizer outer surface protective film further includes a hard coat layer, it becomes possible to strengthen the protective function of a polarizer.

A polarizing plate can be comprised by laminating | stacking the said polarizer outer surface protective film on the outer surface side of the polarizer which consists of polyvinyl alcohol, and laminating | stacking a polarizer inner surface protective film on the inner surface side of this polarizer. In such a polarizing plate, the polarizer outer protective film provided with the base material layer which the easy adhesion process with respect to polyvinyl alcohol was given to the outer surface side of a polarizer is used, and the adhesiveness of a polarizer and a polarizer outer protective film and durability of adhesion are improved. It can raise, and also the intensity | strength and handleability of a polarizing plate improve. Moreover, when using the polarizer inner surface protective film which consists of cellulose ester conventionally used for the inner surface side of a polarizer, since it has small birefringence, it can exhibit a protective function without affecting the performance of a liquid crystal molecule.

A liquid crystal display element can be comprised by laminating | stacking the said polarizing plate on at least one surface side of a liquid crystal cell. In such a liquid crystal display element, since the adhesiveness and adhesive durability of a polarizer and a polarizer outer surface protective film are high, and the intensity | strength and handling property of a polarizing plate are excellent, the various characteristics which a liquid crystal display element has are exhibited stably over a long period of time, and are reliable. This is improved.

As explained above, the polarizer outer surface protective film of this invention is equipped with the transparent synthetic resin base material layer whose inner surface side is surface-treated by the cellulose ester so that adhesion | attachment with the polarizer which consists of polyvinyl alcohol is easy, Therefore, while high transparency is obtained, the adhesiveness with the polarizer which consists of polyvinyl alcohol which is a hydrophilic resin improves remarkably. Moreover, the strength and handleability of such a polarizing plate improve when a polarizing plate is equipped with the said polarizer outer surface protective film. Moreover, when a liquid crystal display element is equipped with the said polarizing plate, a desired characteristic is exhibited stably over a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS It is typical sectional drawing of the polarizer outer surface protective film by this invention.
It is typical sectional drawing of the polarizer outer protective film different from the polarizer outer protective film of FIG.
It is typical sectional drawing of the polarizing plate provided with the polarizer outer surface protective film by this invention of FIG.
It is a schematic diagram which shows the apparatus for manufacturing the polarizing plate by this invention of FIG.
FIG. 5 is a schematic cross-sectional view of a liquid crystal display device having a polarizing plate according to the present invention of FIG. 3.
6 is a schematic diagram showing the structure of a general liquid crystal display element according to the prior art.

(Form to carry out invention)

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail, referring drawings suitably.

The polarizer outer surface protective film 1 of FIG. 1 has the base material layer 2 made of a transparent synthetic resin, and the cellulose-esterified surface treatment layer 3. The polarizer outer protective film 1 can be used as a protective film of a polarizer for improving resistance to impact and handling, and is disposed on the outer surface side (shown in the A direction side) of the liquid crystal display element.

Resin which comprises the base material layer 2 made of transparent synthetic resin is not specifically limited as long as it has the high transparency requested | required as a polarizer outer surface protective film of a liquid crystal display element, Typically, acrylic resin, polycarbonate resin, poly It is selected from the group which consists of a propylene resin, cycloolefin resin, and a polyethylene terephthalate resin. Since these synthetic resins have excellent optical transparency and impact resistance, they can be disposed on the outer surface side of the liquid crystal display element in place of triacetyl cellulose. Among the above synthetic resins, acrylic resins are particularly preferable from the viewpoint of chemical affinity with cellulose esters. Although the base material layer 2 may also contain another arbitrary component, as long as it does not impair transparency and desired intensity | strength, Preferably it contains 90 mass% or more of said synthetic resin, More preferably, it contains 98 mass% or more. As an example of arbitrary components here, a ultraviolet absorber, a stabilizer, a lubricating agent, a processing aid, a plasticizer, an impact resistant agent, a phase difference reducing agent, a gloss removing agent, an antibacterial agent, an antifungal agent, etc. are mentioned.

Acrylic resin used for the base material layer 2 is resin which has frame | skeleton derived from acrylic acid or methacrylic acid. Although it does not specifically limit as an example of acrylic resin, Poly (meth) acrylic acid ester, such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, meta Methyl methacrylate- (meth) acrylic acid copolymer, methyl (meth) acrylate-styrene copolymer, polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl copolymer, methacrylic) Methyl acid- (meth) acrylic acid norbornyl copolymer), and the like. Among these acrylic resins, poly (meth) acrylic acid C1-6 alkyl such as methyl poly (meth) acrylate is preferable, and methyl methacrylate resin is more preferable.

Polycarbonate resin used for the base material layer 2 is resin comprised from the compound called poly-4,4'-isopropylidene diphenyl carbonate. This polycarbonate resin is produced from bisphenol A and carbonyl chloride in the interfacial polycondensation method and from bisphenol A and diphenyl carbonate in the transesterification method.

Polypropylene resin used for the base material layer 2 is resin which has frame | skeleton derived from propylene. Examples of the polypropylene resin include, but are not particularly limited to, a homopolymer of propylene or a copolymer of propylene with at least one monomer selected from the group consisting of ethylene and an alpha -olefin having 4 to 12 carbon atoms. have.

Cycloolefin resin used for the base material layer 2 is resin which has frame | skeleton derived from cycloolefin. Examples of cycloolefin-based resins are not particularly limited, but hydrogenated resins and norbornene-based monomers may be used after the ring-opening (co) polymers of norbornene-based monomers have undergone polymer modification such as maleic acid addition and cyclopentadiene addition as necessary. And resins obtained by addition polymerization of addition-polymerized resins, norbornene-based monomers and olefinic monomers such as ethylene and α-olefins.

As a norbornene-type monomer used in order to obtain the ring-opening (co) polymer of a norbornene-type monomer, For example, norbornene, 2-norbornene, 5-methyl-2-norbornene, 5,5-dimethyl 2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methoxycarbonyl-2-norbornene , 5-cyano-2-norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene, 5-phenyl-5-methyl-norbornene Etc. can be mentioned. As a polymerization catalyst used for this ring-opening polymerization, a tungsten, molybdenum, chromium-based catalyst called a metathesis polymerization catalyst is preferably used.

Polyethylene terephthalate resin used for the base material layer 2 is a polymer obtained by reaction of terephthalic acid and ethylene glycol. The polyethylene terephthalate-based resin may contain other comonomers, but the repeating unit of the polyethylene terephthalate is preferably 80 mol% or more. The polyethylene terephthalate is, for example, by introducing dimethyl terephthalate and ethylene glycol into the reactor, performing a transesterification reaction while gradually raising the internal temperature, transferring the reaction product to the polymerization reactor, and performing a polymerization reaction under high temperature vacuum. Can be generated.

The thickness of the base material layer 2 becomes like this. Preferably they are 10 micrometers or more and 200 micrometers or less, More preferably, they are 20 micrometers or more and 100 micrometers or less. When the thickness of the base material layer 2 is 10 micrometers or more, moderate intensity | strength and rigidity are obtained, it becomes possible to carry out film manufacture stably and easily, and when forming the cellulose-esterified surface treatment layer 3 The handleability of is also good. On the other hand, the line speed, productivity, controllability, etc. at the time of manufacture can be improved by making thickness of the base material layer 2 200 micrometers or less.

As the base material layer 2, an arithmetic mean surface roughness (Ra) of 0.02 or more and 0.06 or less can be used normally. Moreover, the mat (matte) process can be given to the base material layer 2 as needed. The arithmetic mean surface roughness (Ra) of the base material layer subjected to such a mat treatment is preferably 0.07 or more and 2 or less, and more preferably 0.1 or more and 1 or less. By controlling the surface roughness of the base material layer in this range, the occurrence of scratches in the treatment after the film raw material sheet production is prevented, and the handleability is improved. In addition, when the substrate layer is located on the uppermost surface (display surface side) of the liquid crystal display element, high antireflection performance is obtained, and when located on the lowermost layer, sticking with other layers is effectively prevented. Moreover, generally, when winding up the manufactured film raw material sheet, it is necessary to emboss (knurling) both ends of the width direction of a film, and to prevent blocking. When the knurling treatment is performed on the film, the treated portions at both ends of the film cannot be used, so the portion must be cut and discarded. Moreover, in the winding operation of a film, masking may be performed by the protective film in order to prevent a wound. However, by setting the arithmetic mean surface roughness of the base material layer to a predetermined range as described above, blocking can be prevented without performing the knurling treatment, thereby simplifying the manufacturing process and enabling both end portions in the film width direction to be used. It can wind up over a long length, without causing a malfunction of a film. In addition, since the base layer has a suitable surface roughness, the occurrence of wounds during winding is effectively suppressed, and the above masking is also unnecessary.

The retardation value Re of the base layer 2 is preferably -15 nm or more and 15 nm or less, more preferably -5 nm or more and 5 nm or less. The substrate layer has such a small retardation, thereby suppressing the conversion action of the polarized light direction of the transmitted light by the polarizer outer surface protective film provided with the substrate layer, and optimizing and controlling the polarization of the polarizer in the transmission axis direction. The influence which a polarizer outer surface protective film exerts can be suppressed. Here, the "retardation value (Re)" means the x- and y-directions and the thickness of the base layer in the fast-axis and slow-axis directions that are orthogonal to each other in the crystal axis directions on the plane of the base layer. Is a value calculated as d, and the refractive indexes in the x and y directions are nx and ny (nx ≠ ny), and Re = (ny-nx) d.

Although the manufacturing method of the base material layer 2 is not specifically limited, For example, additives, such as a flake raw material of a synthetic resin, a plasticizer, are mixed by a conventionally well-known mixing method, and it is made into a thermoplastic resin composition previously, and an optical film is made into It can manufacture. This thermoplastic resin composition is obtained by, for example, pre-blending with a mixer such as an omni mixer and then extruding and kneading the obtained mixture. In this case, the kneader used for extrusion kneading is not particularly limited, and for example, a conventionally known kneader such as an extruder such as a single screw extruder or a twin screw extruder or a pressurized kneader can be used.

As a film shaping | molding method of the base material layer 2, well-known methods, such as the solution casting method (solution flexible method), the melt extrusion method, the calender method, the compression molding method, are mentioned, for example. Among these, the solution casting method (solution softening method) and the melt extrusion method are preferable. Under the present circumstances, you may use the thermoplastic resin composition extruded and kneaded previously, and after melt | dissolving a synthetic resin and other additives, such as a plasticizer, in a solvent and making it a uniform liquid mixture, respectively, of the solution casting method (solution softening method) or the melt-extrusion method You may provide to a film forming process.

As a solvent used for the solution casting method (solution flexible method), For example, Chlorine solvents, such as chloroform and dichloromethane; Aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; Alcohol solvents such as methanol, ethanol, isopropanol, n-butanol and 2-butanol; Methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, diethyl ether; Etc. can be mentioned. 1 type of these solvents may be used and may use 2 or more types together. As an apparatus for performing the solution casting method (solution softening method), a drum type casting machine, a band type casting machine, a spin coater, etc. are mentioned, for example.

Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature of the film at the time of melt extrusion becomes like this. Preferably it is 150 degreeC or more and 350 degrees C or less, More preferably, it is 200 degreeC or more and 300 degrees C or less. When film-forming by T-die method, T-die is attached to the front-end | tip of a well-known single screw extruder or a twin screw extruder, the film extruded in film shape can be wound up, and a roll-shaped film can be obtained. At this time, it is also possible to set it as the uniaxial stretching process by adjusting the temperature of a winding roll suitably, and extending | stretching in an extrusion direction. Moreover, by adding the process of extending | stretching a film to the direction perpendicular | vertical to an extrusion direction, it is also possible to add processes, such as sequential biaxial stretching and simultaneous biaxial stretching.

The base layer 2 may be an unstretched film or a stretched film. When extending | stretching, a uniaxial stretched film may be sufficient and a biaxially stretched film may be sufficient. In the case of using a biaxially stretched film, simultaneous biaxial stretching may be performed, or successive biaxial stretching may be performed. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved.

As extending | stretching temperature at the time of performing an extending process, it is preferable to carry out in the vicinity of the glass transition temperature of the thermoplastic resin composition of a film raw material, and it is preferable to carry out at (glass transition temperature -30) degreeC-(glass transition temperature +100) degreeC specifically ,. More preferably, it is (glass transition temperature-20) degreeC-(glass transition temperature +80) degreeC. If the stretching temperature is lower than (glass transition temperature -30) 占 폚, since a sufficient stretching ratio cannot be obtained, it is not preferable. If the stretching temperature is higher than (glass transition temperature + 100) ° C, it is not preferable because a flow (flow) of the resin occurs and stable stretching cannot be performed.

The draw ratio defined by the area ratio is preferably 1.1 times or more and 25 times or less, and more preferably 1.3 times or more and 10 times or less. When the draw ratio is smaller than 1.1 times, since it does not lead to the improvement of toughness accompanying extending | stretching, it is unpreferable. When the draw ratio is larger than 25 times, the effect of raising the draw ratio is not confirmed.

The stretching speed (one direction) is preferably in the range of 10 to 20000% / minute, more preferably in the range of 100 to 10000% / minute. If it is slower than 10% / min, it is not preferable because it takes time to obtain a sufficient draw ratio and the manufacturing cost increases. If it is faster than 20000% / min, the breakage of the stretched film may occur, which is not preferable. In addition, in order to stabilize the optical isotropy and the mechanical characteristics of the base material layer 2, heat treatment (annealing) or the like may be performed after the stretching treatment.

Although it does not specifically limit as a plasticizer, It is preferable to have a functional group which can interact with a synthetic resin and a hydrogen bond etc. so that a haze may not generate | occur | produce in the base material layer 2 or it does not bleed out or volatilizes from the base material layer 2. Do. Examples of such plasticizers include, but are not particularly limited to, phosphoric acid ester plasticizers, phthalic acid ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol plasticizers, glycolate plasticizers, citric acid ester plasticizers, and fatty acid esters. A plasticizer, a carboxylic ester plasticizer, a polyester plasticizer, etc. are mentioned.

The cellulose ester constituting the cellulose esterified surface treatment layer 3 is not particularly limited as long as it is saponified with alkali to generate hydroxyl groups, but is not limited to triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate. It is preferable to select from the group which consists of. These cellulose esters generate a hydroxyl group which is a hydrophilic group by saponifying with alkali, whereby affinity with a polarizer made of polyvinyl alcohol, which is a hydrophilic resin, becomes high and can be reliably bonded.

The thickness of the cellulose-esterified surface treatment layer 3 becomes like this. Preferably it is 0.01 micrometer or more and 3 micrometers or less, More preferably, it is 0.03 micrometer or more and 1.5 micrometer or less, Most preferably, it is 0.04 micrometer or more and 1 micrometer or less. By making the thickness of the cellulose-esterified surface treatment layer 3 into 0.01 micrometer or more, adhesion | attachment with the hydroxyl group produced by saponifying this cellulose ester and the polyvinyl alcohol which comprises a polarizer is assured. Moreover, by making thickness of the cellulose-esterification surface treatment layer 3 into 3 micrometers or less, the thickness of the polarizer outer surface protective film 1 can be kept thin enough, and the thickness of the whole polarizing plate which included the polarizer outer surface protective film 1 was included. The increase of can be suppressed.

The solvent of the cellulose ester coating liquid for forming the cellulose-esterified surface treatment layer 3 is not particularly limited as long as it is an organic solvent that sufficiently dissolves the cellulose ester. For example, dioxane, acetone, methyl ethyl ketone, N, N-dimethylformamide, methyl acetate, ethyl acetate, trichloroethylene, methylene chloride, ethylene chloride, tetrachloroethane, trichloroethane, chloroform and the like can be used. Moreover, you may add a ultraviolet absorber, a lubricating agent, a mat agent, an antistatic agent, a crosslinking agent, an activator etc. to the coating liquid of the cellulose ester for forming the cellulose-esterification surface treatment layer 3 as needed. In particular, a crosslinking agent is preferable at the point which promotes adhesion | attachment with the polyvinyl alcohol which comprises a polarizer. As an example of such a crosslinking agent, a polyvalent epoxy compound, an aziridine compound, an isocyanate compound, an alum, a boron compound, etc. are mentioned, for example.

The coating solution of cellulose ester for forming the cellulose-esterified surface treatment layer 3 can be applied to the substrate layer 2 using a known method such as a gravure coater, a dip coater, a reverse roll coater, an extrusion coater, or the like. . Although it does not specifically limit as a method of drying after apply | coating such a coating liquid, Although well-known means can be used, it is preferable to make the residual solvent amount after drying into 5 mass% or less. If the amount of residual solvent is large, bubbles may be generated in the adhesive interface in the drying process after laminating the polarizer outer protective film to the polarizer, which is not preferable.

In the polarizer outer protective film 1, the surface of the base material layer 2 on the side not surface-treated with cellulose ester is optionally various functional layers, for example, an antiglare layer, an antireflection layer, an antiglare layer, a low refractive index. It may be covered by an antireflection layer such as a layer, an antistatic layer, a hard coat layer (curable resin layer), an optical compensation layer, or the like. For example, when a polarizer outer surface protective film is further equipped with an anti-glare layer (antireflection layer), an anti-glare function can be exhibited in addition to the protective function with respect to a polarizer. Moreover, the protective function with respect to a polarizer is reinforced by the polarizer outer surface protective film further providing a hard-coat layer.

As such an anti-glare layer, for example, a technique of forming an uneven structure on the surface of the film by an embossing method or a coating liquid in which particles are mixed in the binder matrix forming material is applied to the surface of the film, and the unevenness is dispersed by dispersing the particles in the binder matrix. Techniques for forming the structure can be used. Moreover, as a hard coat layer, what was formed from active-line cured resin can be used, for example. Examples of such active ray cured resins include urethane acrylate resins, polyester acrylate resins, epoxy acrylate resins, polyol acrylate resins, epoxy resins, and the like.

As described above, according to the polarizer outer surface protective film according to the present invention, the inner surface side is provided with a base layer surface-treated with a cellulose ester so as to facilitate adhesion with the polarizer made of polyvinyl alcohol. By generating a hydroxyl group through the saponification process by alkali mentioned later, affinity and adhesiveness with polyvinyl alcohol which is a hydrophilic resin which comprises a polarizer are improved effectively.

The polarizer outer surface protective film 31 of FIG. 2 has the base material layer 2 made of a transparent synthetic resin, the primer layer 32, and the cellulose-esterification surface treatment layer 3. As shown in FIG. Since the base material layer 2 and the cellulose-esterified surface treatment layer 3 are the same as that of the polarizer outer surface protective film 1 of FIG. 1, they attach | subject the same number and abbreviate | omit description.

The primer layer 32 is not particularly limited as long as the primer layer 32 includes a chemical species having chemical affinity with both the substrate layer 2 and the cellulose esterified surface treatment layer 3, but is formed from an aqueous latex. desirable. The aqueous latex is composed of a component exhibiting lipophilic composition consisting of a polymer of a monounsaturated monomer or a copolymer of two or more unsaturated monomers. As aqueous latex, what is synthesize | combined by a general emulsion polymerization method may be used, and a commercial latex may be used. Although water is used as the main solvent of the aqueous latex, a small amount of an organic solvent miscible with water may be used. You may add arbitrary components, such as an antistatic agent, surfactant, a thickener, a stabilizer, a crosslinking agent, a curing catalyst, to aqueous latex suitably. Solid content of aqueous latex is typically 20% or more and 50% or less. It is preferable that the particle diameter of the polymer particle which comprises aqueous latex is 0.005 micrometer or more and 0.5 micrometer from a viewpoint of dispersion stability.

As a specific example of the said unsaturated monomer, acrylic acid, methacrylic acid, a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, an amyl group, a hexyl group, 2-ethylhexyl group, jade as a substituent Methyl, tert-octyl, dodecyl, 2-chloroethyl, 2-bromoethyl, 4-chlorobutyl, cyanoethyl, 2-acetoxyethyl, dimethylaminoethyl, benzyl, methoxybenzyl, 2 -Chlorocyclohexyl group, cyclohexyl group, furfuryl group, tetrahydrofurfuryl group, phenyl group, 5-hydroxypentyl group, 2,2-dimethyl-3-hydroxypropyl group, 2-methoxyethyl group, glycy Dyl group, acetoacetoxyethyl group, 3-methoxybutyl group, 2-ethoxyethyl group, 2-iso-propoxy group, 2-butoxyethyl group, 2- (2-methoxyethoxy) ethyl group, 2- (2 -Butoxyethoxy) ethyl group, ω-methoxy oligooxyethylene group, ω-hydroxy oligooxyethylene group, 1-bromo-2-methoxyethyl group, or 1,1-dichloro-2-ethoxy Acrylic acid derivatives and methacrylic acid derivatives having an ethyl group;

Acrylamide, methacrylamide, methyl group, ethyl group, n-propyl group, n-butyl group, tert-butyl group, n-octyl group, dodecyl group, cyclohexyl group, benzyl group, hydroxymethyl group, methoxyethyl group as substituents , Acrylamide derivative, methacrylamide derivative, N, N-dimethyl group or N, N-diethyl group which is N-mono substituted derivative having dimethylaminopropyl group, phenyl group, acetacetoxy propyl group or cyanoethyl group Amide derivatives, methacrylamide derivatives;

Vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caprate, vinyl chloroacetate, vinyl methoxy acetate, vinyl phenyl acetate, vinyl benzoate and vinyl salicylate; Olefins such as dicyclopentadiene, ethylene, propylene, 1-butene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene and 2,3-dimethylbutadiene; Styrenes such as styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromostyrene, and vinyl benzoate methyl ester; Crotonic acid esters such as butyl crotonate and hexyl crotonate; Itaconic acid ester, such as itaconic acid monomethyl ester, itaconic acid dimethyl, itaconic acid monobutyl ester, itaconic acid diethyl, and itaconic acid dibutyl; Fumaric acid esters such as diethyl fumarate, dimethyl fumarate and dibutyl fumarate; Vinyl ketones such as methyl vinyl ketone, phenyl vinyl ketone and methoxy ethyl vinyl ketone; Heterocyclic containing vinyl monomers, such as N-vinylpyridine and 2- and 4-vinylpyridine, vinylimidazole, vinyloxazole, vinyltriazole, and N-vinyl-2-pyrrolidone; Unsaturated nitriles, such as an acrylonitrile and methacrylonitrile, are mentioned.

The aqueous latex is a substrate layer (2) using a known dip coating method, air knife coating method, curtain coating method, roller coating method, wire bar coating method, gravure coating method, extrusion coating method (die coating method), or the like. ) Can be applied. Subsequently, the primer layer 32 can be formed by drying the applied aqueous latex. Preferably the thickness of the primer layer 32 is 0.01 micrometer or more and 1 micrometer or less, More preferably, they are 0.05 micrometer or more and 0.1 micrometer or less.

As total thickness of the primer layer 32 and the cellulose-esterification surface treatment layer 3 in the polarizer outer surface protective film 31, Preferably they are 0.02 micrometer or more and 4 micrometers or less, More preferably, they are 0.05 micrometer or more and 2 micrometers or less. to be. By making the total thickness of the primer layer 32 and the cellulose-esterified surface treatment layer 3 into 0.02 micrometer or more, adhesion | attachment with the hydroxyl group produced by saponification of this cellulose ester, and the polyvinyl alcohol which comprises a polarizer is assured. Moreover, by making the total thickness of the primer layer 32 and the cellulose-esterification surface treatment layer 4 into 4 micrometers or less, the thickness of the polarizer outer side protective film 31 can be kept thin enough, and the polarizer outer side protective film 1 Increase of the thickness of the whole polarizing plate containing this can be suppressed.

In the polarizer outer protective film 31, the surface of the base material layer 2 on the side not surface-treated with cellulose ester via the primer layer 32 is optionally a variety of functional layers, for example, an antiglare layer, It may be covered with an antireflection layer such as an antireflection layer, an antiglare layer, a low refractive index layer, an antistatic layer, a hard coat layer (curable resin layer), an optical compensation layer, or the like. For example, when a polarizer outer surface protective film is further equipped with an anti-glare layer (antireflection layer), an anti-glare function can be exhibited in addition to the protective function with respect to a polarizer. Moreover, when the polarizer outer surface protective film 31 further includes a hard coat layer, the protective function for the polarizer is enhanced.

As such an anti-glare layer, for example, a technique of forming an uneven structure on the surface of the film by an embossing method or a coating liquid in which particles are mixed in the binder matrix forming material is applied to the surface of the film, and the unevenness is dispersed by dispersing the particles in the binder matrix. Techniques for forming the structure can be used. Moreover, as a hard coat layer, what was formed from active-line cured resin can be used, for example. Examples of such active ray cured resins include urethane acrylate resins, polyester acrylate resins, epoxy acrylate resins, polyol acrylate resins, epoxy resins, and the like.

As mentioned above, according to the polarizer outer surface protective film 31, the inner surface side is equipped with the base material layer surface-treated by the cellulose ester through the primer layer so that adhesion | attachment with the polarizer which consists of polyvinyl alcohol is easy, As this cellulose ester generates a hydroxyl group through saponification treatment with alkali similarly to the polarizer outer surface protective film 1, the affinity and adhesiveness with polyvinyl alcohol which is the hydrophilic resin which comprises a polarizer improves effectively.

The polarizing plate 4 of FIG. 3 is provided with the polarizer outer surface protective film 1 of FIG. 1 in the outer surface side (shown A direction side) of the polarizer 6 which consists of polyvinyl alcohol, and the inner surface side of the polarizer 6 Has a structure provided with the polarizer inner surface protective film 5 which consists of cellulose esters conventionally used. An adhesive agent (not shown) is bonded between the polarizer 6 and the polarizer outer protective film 1, and between the polarizer 6 and the polarizer inner protective film 5.

The polarizer 6 is obtained by dyeing a polyvinyl alcohol resin film with a dichroic substance (for example, iodine or a dichroic dye) and uniaxially stretching the polyvinyl alcohol resin film. Preferably the polymerization degree of the polyvinyl alcohol which comprises this polyvinyl alcohol resin film is 100 or more and 5000 or less, More preferably, it is 1400 or more and 4000 or less. A polyvinyl alcohol resin film can be shape | molded by a well-known method (for example, the casting method which casts the solution which melt | dissolved resin in water or the organic solvent, the casting method, etc.). Although the thickness of the polarizer 6 changes with the objective and use of the LCD which can use the polarizing plate 4, they are 5 micrometers or more and 100 micrometers or less typically. The polarizer 6 may contain arbitrary components other than a polyvinyl alcohol resin and a dichroic substance, unless the polarizing function and optical transparency are impaired.

As a typical manufacturing method of the polarizer 6, the series of manufacturing processes which a polyvinyl alcohol resin film consists of a swelling, dyeing, crosslinking, extending | stretching, water washing, and a drying process are employ | adopted. In each processing process except a drying process, a process is performed by immersing a polyvinyl alcohol resin film in the bath of the solution used for each process. The order, recovery and execution of each treatment of swelling, dyeing, crosslinking, stretching, washing with water and drying can be appropriately set depending on the purpose, materials used and conditions. For example, an extending | stretching process may be performed before dyeing process, and may be performed simultaneously with swelling process etc. Moreover, it is preferable to perform crosslinking process before and behind an extending | stretching process.

The swelling process in a series of manufacturing processes of the polarizer 6 can be performed by immersing a polyvinyl alcohol resin film in the process bath filled with water. Glycerine, potassium iodide, etc. can be added to this treatment bath suitably. Typically, the temperature of the treatment bath in the swelling step is about 20 to 60 ° C, and the immersion time in the treatment bath is about 0.1 to 10 minutes. A dyeing process can be performed by immersing a polyvinyl alcohol resin film in the process bath containing dichroic substances, such as iodine. As a solvent used for the solution of this process bath, water is generally used. A dichroic substance is used in the ratio of 0.1-1.0 mass part with respect to 100 mass parts of solvents. Typically, the temperature of the process bath of a dyeing process is about 20-70 degreeC, and immersion time is about 1-20 minutes.

A crosslinking process can be performed by immersing the dyed polyvinyl alcohol-type resin film in the process bath containing a crosslinking agent. Examples of the crosslinking agent include boron compounds such as boric acid, glyoxal, glutaaldehyde and the like. As a solvent used for the solution of this process bath, water is generally used. Typically, the temperature of the process bath of a crosslinking process is about 20-70 degreeC, and immersion time is about 1 second-about 15 minutes. The stretching step may be performed at any stage. It is preferable to make draw ratio of a polyvinyl alcohol resin film into 5 times or more. As the stretching method, for example, a wet stretching method can be adopted. As a solution of the process bath in this case, the solution which added the compound of various metal salts, iodine, boron, or zinc in water or an organic solvent is preferable.

A water washing process can be performed by immersing the polyvinyl alcohol resin film in which the various processes were performed in the water washing bath. By this water washing process, unnecessary residue of a polyvinyl alcohol resin film can be wash | cleaned. The water washing bath may be pure water or an aqueous solution of iodide (potassium iodide, sodium iodide, etc.) may be used. The temperature of the water washing bath is preferably 10 to 60 ° C. Immersion time is typically 1 second-1 minute. The number of times of washing with water may be only once or multiple times. As a drying process, natural drying, ventilation drying, heat drying can be employ | adopted, for example. Typically, the drying temperature is 20 to 80 ° C., and the drying time is 1 to 10 minutes. The polarizer 6 can be manufactured by performing each said process.

The polarizer inner surface protective film 5 which consists of cellulose esters conventionally used melt | dissolves the flake raw material and a plasticizer of cellulose ester in methylene chloride, and makes it a viscous liquid, and it melt | dissolves a plasticizer in this and dopes it continuously from a melt-extruder, It is manufactured by casting on a metal belt such as stainless steel, which is rotated in a flexible manner, drying, peeling off the belt in a less dry state, and then drying and winding up. The cellulose ester is preferably selected from the group consisting of triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate, with triacetyl cellulose being particularly preferred.

Before the polarizer outer surface protective film 1 adheres to the polarizer 6, it is necessary to saponify the cellulose-esterified surface treatment layer 3 with alkali. By this saponification, the ester group of a cellulose ester is converted into the hydroxyl group which is a hydrophilic group, and by this, chemical affinity with the polarizer outer surface protective film 1 and the polarizer 6 formed from polyvinyl alcohol which is a hydrophilic resin becomes high, The mutual adhesion is remarkably improved.

As aqueous alkali solution used for saponification treatment, sodium hydroxide, potassium hydroxide, calcium hydroxide, the aqueous solution of lithium hydroxide, etc. can be used, for example. The concentration of these metal hydroxides is generally 5% by mass or more and 40% by mass or less. Moreover, it is preferable that the temperature of a saponification process is 10 degreeC or more and 80 degrees C or less. When the concentration of the metal hydroxide is 5% by mass or less, or when the temperature of the saponification treatment is 10 ° C or less, the time required for the saponification treatment becomes long, which is not preferable. A saponification process is performed by immersing the polarizer outer surface protective film 1 in the above alkali aqueous solution bath over a suitable time.

The polarizer outer surface protective film 1 provided in the saponification process, and the polarizer 6 which consists of polyvinyl alcohol are attached by the apparatus 7 typically shown in FIG. The apparatus 7 for attaching the plurality of films shown in FIG. 4 includes a polarizer film roll 8 in which a film-shaped polarizer 6 is wound in a roll shape, and a polarizer outer protective film 1 wound in a roll shape. The polarizer outer side protective film roll 9, the means 10 for supplying an adhesive agent, and the nip 11 for pressurizing and bonding the polarizer 6 and the polarizer outer side protective film 1 through an adhesive agent are provided. .

As an adhesive used in order to adhere the cellulose-esterified surface treatment layer 3 of the polarizer outer surface protective film 1 and the polarizer 6 by the apparatus 7, for example, polyvinyl alcohol, polyvinyl butyral, etc. Polyvinyl alcohol adhesives, vinyl latexes such as butyl acrylate, and the like. Usually, these adhesive agents are used as aqueous solution. As solid content concentration in the resin solution of an adhesive agent, when coating property, anti-rust stability, etc. are considered, it is 0.1-15 mass% preferably. Moreover, as a viscosity of the resin solution of an adhesive agent, the range of 1-50 mPa * s is preferable, for example.

In the device 7, the film-shaped polarizer 6 supplied from the polarizer film roll 8 and the saponified polarizer outer protective film 1 supplied from the polarizer outer protective film roll 9 are nips 11. The cellulose esterified surface treatment layer of the polarizer 6 and the polarizer outer protective film 1 was fed by an appropriate amount of adhesive so as to be fed in the direction toward and sandwiched between these films, and then pressurized with the nip 11. 3) is affixed and the structure by which the polarizer outer surface protective film 1 was laminated | stacked on the single side | surface of the polarizer 6 is obtained. Next, the polarizing plate 4 is obtained by laminating the polarizer inner surface protective film 5 using the same means on the surface of the polarizer 6 on which the polarizer outer surface protective film 1 is not laminated. The thickness of the polarizing plate 4 is 10 micrometers or more and 100 micrometers or less typically.

As mentioned above, according to the polarizing plate which has the polarizer outer surface protective film by this invention, since the easily bonding process is given to the base material layer made of synthetic resin arrange | positioned at the outer surface side of the polarizer which consists of polyvinyl alcohol, polyvinyl alcohol The adhesiveness and peeling durability of the polarizer which consists of these, and a polarizer outer surface protective film become high, and the intensity | strength and handleability of a polarizing plate improve by this. Further, by disposing a polarizer inner surface protective film made of a cellulose ester having a small birefringence (i.e., no orientation) on the inner surface side of the polarizer, the protective function of the polarizer can be imparted without affecting the performance of the liquid crystal molecules. .

In the liquid crystal display element 12 of FIG. 5, the adhesive layer 16 is formed on both surfaces of the liquid crystal cell 13 in which the liquid crystal layer 15 is sandwiched by the transparent medium layer 14 (for example, glass). It consists of attaching the polarizing plate 4 (the base material layer 2, the cellulose-esterification surface treatment layer 3, the polarizer inner surface protective film 5 and the polarizer 6) of FIG. 3 by this invention. The polarizer outer surface protective film (base material layer 2 and the cellulose-esterification surface treatment layer 3) which concerns on this invention is arrange | positioned only at the outer surface side of the polarizer 6, The polarizer inner surface protective film which consists of cellulose esters conventionally used. 5 is disposed on the inner surface side of the polarizer 6 (the A-direction side shown is the outer surface side). The material which comprises the liquid crystal layer 15, the transparent medium layer 14, and the adhesive bond layer 16 of the liquid crystal cell 213 is not specifically limited, A well-known thing can be used. Moreover, in the liquid crystal display element, you may use the polarizing plate 4 (polarizing plate by this invention) of FIG. 3 on one surface side of a liquid crystal cell, and may use the other polarizing plate by a prior art on the other surface side of a liquid crystal cell.

The liquid crystal display element provided with the polarizing plate in which the polarizer outer surface protective film by this invention was arrange | positioned has the adhesiveness of the polarizer outer surface protective film, and the adhesiveness of a polarizer and a polarizer outer surface protective film is excellent in durability to peeling. It is high and is excellent in the strength and handleability of a polarizing plate. Therefore, various characteristics of the liquid crystal display element are exhibited continuously and stably over a long period of time, thereby increasing the reliability of the entire apparatus.

(Example)

Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not interpreted limitedly based on description of this Example.

[Formation of Base Layer Made of Acrylic Resin]

100 parts by mass of methyl methacrylate / methyl acrylate copolymer (molar ratio 9: 1), 1 part by mass of [2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole], 400 mass parts of methylene chloride and 100 mass parts of methanol were thrown into the airtight container, and it melt | dissolved under pressure at 80 degreeC, and obtained the dope composition. After filtering and cooling this dope composition, the solvent was evaporated until it was uniformly flexible on the endless stainless steel band, and peeling was possible, and it peeled from an endless stainless steel band, and also it dried and dried, and a film thickness of 30 micrometers An acrylic resin film (base material layer made of transparent synthetic resin) was obtained. This acrylic resin film is referred to as Sample A1.

[Formation of Base Material Layer Made of Polyethylene Terephthalate Resin]

The ethylene glycol slurry to which the columnar silica was added was prepared, this ethylene glycol slurry was heat-treated at 190 degreeC for 2 hours, and then this was transesterified with dimethyl terephthalate, and then it polycondensed and produced the ethylene terephthalate pellet. Next, after drying the resin obtained from this pellet under reduced pressure at 180 degreeC for 3 hours, it supplied to the extruder and melted by heating at 310 degreeC. Then, the unstretched film was produced by extruding melted resin from the extruder to sheet form, and cooling and solidifying on the casting drum of surface temperature of 30 degreeC. Next, the unstretched film was stretched 4 times in the longitudinal direction at 100 ° C. by roll stretching, and stretched 4 times in the width direction at 110 ° C. using a tenter. Subsequently, this biaxially stretched film was heat-treated at 235 ° C. (crystallization temperature) for 5 seconds to crystallize, thereby producing a polyethylene terephthalate resin film having a thickness of 40 μm. This polyethylene terephthalate resin film is referred to as Sample A2.

[Formation of Cellulose Esterized Surface Treatment Layer]

Using a dip coater, triethyl cellulose methyl ethyl ketone solution (20% by mass) was applied to one surface of the acrylic resin film of Sample A1, and triethyl cellulose surface treatment layer (thickness) was dried. A polarizer protective film having 0.05 μm) was obtained. The saponification process was performed at 40 degreeC using the sodium hydroxide aqueous solution (concentration 20 mass%) with respect to the triacetyl cellulose surface treatment layer. This saponified polarizer protective film is referred to as Sample B1.

[Formation of primer layer and cellulose esterified surface treatment layer]

As a water-based latex, the water dispersion latex (mass ratio 30/20/25/25) of the butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl acrylate copolymer of 30 mass% of solid content was used, And apply | coated on the surface of the polyethylene terephthalate resin film of sample A2, and it dried and formed the primer layer of thickness 0.5micrometer. Subsequently, using a dip coater, a methylethyl ketone solution of triacetyl cellulose (20% by mass) is applied to this primer layer, and methyl ethyl ketone is dried to form a triacetylcellulose surface treatment layer, and a primer layer and a tree The polarizer protective film whose total thickness of the acetylcellulose surface treatment layer was 2.0 micrometers was obtained. In addition, the saponification process was performed at 40 degreeC using the sodium hydroxide aqueous solution (concentration 20 mass%) with respect to the triacetyl cellulose surface treatment layer. This saponified polarizer protective film is referred to as Sample B2.

[Formation of polarizer]

The polyvinyl alcohol film with a film thickness of 200 micrometers was uniaxially stretched (temperature 110 degreeC, draw ratio 5 times), and the film with a film thickness of 40 micrometers was obtained. The film was immersed in an aqueous solution containing 0.15 g of iodine and 10 g of potassium iodide for 60 seconds, and then immersed in an aqueous solution at 68 ° C. containing 12 g of potassium iodide and 7.5 g of boric acid. This was washed with water and dried to obtain a polarizer.

Example 1

The saponified polarizer protective film of Sample B1 and the polarizer were cut to a size of 18 cm x 5 cm, and the solid content concentration was superimposed on them through an adhesive of 2 mass% polyvinyl alcohol aqueous solution. It was attached while removing. The laminate 1 was obtained by inserting this into a laminator pressurized at ² kg / cm ² and drying at 80 ° C. In this adhesion | attachment, the triacetylcellulose surface treatment layer of sample B1 and the said polarizer were made to adhere | attach.

[Example 2]

The saponified polarizer protective film of sample B2 and the polarizer were attached by the same means as in Example 1, to obtain a laminate 2. In this adhesion | attachment, the triacetyl cellulose-ized surface treatment layer of sample B2 and the said polarizer were made to adhere | attach.

Comparative Example 1

The acrylic resin film of the sample A1 and the said polarizer were affixed by the same means as the said Example 1, and the laminated body 3 was obtained.

Comparative Example 2

The polyethylene terephthalate resin film of sample A2 and the said polarizer were affixed by the same means as the said Example 1, and the laminated body 4 was obtained.

About the laminated bodies 1-4 obtained above, the characteristic evaluation regarding initial stage adhesiveness and durability was performed by the following method.

(1) initial adhesiveness

Two layers of the laminate were peeled off by hand, and evaluated in the following three steps according to the degree of occurrence of material destruction.

Good: Material breakdown occurs.

Somewhat bad: Some material breakdown occurs, but the peeling area between the sample and the polarizer is large.

Poor: The sample is completely peeled off between the polarizer.

(2) durability

The laminate was left to stand at 75 ° C. for 90 hours under conditions of 90% RH to observe changes in appearance and to measure the width of peeling from the ends. Evaluation criteria were as follows.

Good: within 0.5mm

Somewhat poor: 0.5 mm or more and 1.5 mm or less

Poor: 1.5mm or more

When the initial adhesion tests were carried out on the laminates 1 and 2 of Examples 1 and 2, material destruction occurred, and it was found that the initial adhesion was good. Moreover, when the durability test was done about the laminated body 1, peeling was 0.2 mm and it was also excellent in peeling durability under strict conditions. When the durability test was done about the laminated body 2, peeling was 0.3 mm and it was also excellent in peeling durability under strict conditions.

On the other hand, when the initial adhesion test was done about the laminated bodies 3 and 4 of the comparative examples 1 and 2, it turned out that the sample A1 or A2 peels from a polarizer without applying a large force and it is inferior to initial adhesiveness. Moreover, when the durability test was done about the laminated body 3, peeling was 1.8 mm and inferior to peeling durability. When the durability test was done about the laminated body 4, peeling was 2.0 mm and peeling durability was inferior.

Thus, since the protective film for polarizer outer surfaces by this invention is equipped with the base material layer in which one surface is surface-treated with a cellulose ester, compared with the film which consists of a base material layer in which such surface treatment is not performed. The adhesion to polyvinyl alcohol and the peeling durability were remarkably improved.

In the liquid crystal display element using the polarizing plate provided with the polarizer outer surface protective film by this invention, since adhesion | attachment between the polarizer outer surface protective film and a polarizer was performed reliably, the reliability of a liquid crystal display element and the whole electronic device provided with this increases. Therefore, such a liquid crystal display element can be used in various fields from small products, such as an electronic calculator and a clock, to large products, such as an automobile instrument, a PC monitor, and a television.

1 polarizer outer protective film 2 base material layer
3 Cellulose esterification surface treatment layer 4 Polarizing plate
5 polarizer inner protective film 6 polarizer
7 Apparatus for manufacturing polarizing plate 8 Polarizer film roll
9 polarizer outer protective film roll 10 glue supply means
11 Nip 12 Liquid Crystal Display Element
13 Liquid Crystal Cell 14 Transparent Media Layer
15 Liquid Crystal Layer 16 Adhesive Layer
31 Polarizer outer protective film 32 Primer layer

Claims (12)

As a polarizer outer surface protective film arrange | positioned at the outer surface side of a liquid crystal display element,
Base material layer made of transparent synthetic resin,
The cellulose-esterified surface treatment layer formed in the inner surface side of this base material layer is provided, The polarizer outer surface protective film characterized by the above-mentioned. The polarizer outer protective film according to claim 1, wherein the cellulose esterified surface treatment layer is formed by contacting a surface treatment agent containing a cellulose ester and a solvent with an inner surface of the substrate layer. The resin constituting the base layer is at least one member selected from the group consisting of acrylic resins, polycarbonate resins, polypropylene resins, cycloolefin resins and polyethylene terephthalate resins. Polarizer outer protective film. The polarizer outer protective film according to claim 2, wherein the cellulose ester is one or two or more selected from the group consisting of triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate. The thickness of the said cellulose-esterified surface treatment layer is 0.01 micrometer or more and 3 micrometers or less, The polarizer outer surface protective film of Claim 1 characterized by the above-mentioned. The polarizer outer protective film according to claim 1, further comprising a primer layer between the substrate layer and the cellulosic esterification surface treatment layer. The polarizer outer protective film according to claim 6, wherein the primer layer is formed from an aqueous latex. The method of claim 7, wherein the aqueous latex is (meth) acrylic acid, (meth) acrylic acid derivatives, (meth) acrylamides, (meth) acrylamide derivatives, vinyl esters, olefins, styrenes, crotonic acid esters, eta A polarizer outer protective film comprising a polymer obtained from at least one unsaturated monomer selected from the group consisting of cholic acid esters, fumaric acid esters, vinyl ketones, heterocyclic vinyl monomers and unsaturated nitriles. The total thickness of the said primer layer and the cellulose-esterified surface treatment layer is 0.02 micrometer or more and 4 micrometers or less, The polarizer outer surface protective film of Claim 6 characterized by the above-mentioned. The polarizer outer protective film according to claim 1, further comprising an antireflection layer or a hard coat layer laminated on an outer surface side of the base material layer. A polarizer made of polyvinyl alcohol,
The polarizer outer surface protective film of Claim 1 laminated | stacked on the outer surface of this polarizer,
A polarizer inner surface protective film laminated | stacked on the inner surface of a polarizer, The polarizing plate characterized by the above-mentioned. With a liquid crystal cell,
The polarizing plate of Claim 11 laminated | stacked on at least one surface side of this liquid crystal cell is provided, The liquid crystal display element characterized by the above-mentioned.

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