KR20130089605A - Polarizer protection film, polarizing plate and liquid crystal display element - Google Patents

Abstract

PURPOSE: A polarizer protection film, a polarizing plate, and a liquid crystal display device are provided to suppress the change of a retardation value of the polarizer protection film. CONSTITUTION: A of the polarizer protection film (1) comprises a base layer (2), a first control layer (3), an adhesion convenience layer (4), and a second control layer (5). The base layer is formed of acrylic resin with a main component. The first control layer is laminated on one face side of the base layer and controls moisture permeability. The adhesion convenience layer is laminated on one face side of the first control layer. The second control layer is laminated on another face side of the base layer and controls the moisture permeability.

Description

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

This invention relates to a polarizer protective film, the polarizing plate provided with this polarizer protective film, and the liquid crystal display element provided with this polarizing plate.

Liquid crystal display (LCD) is widely used as a flat panel display utilizing features such as thin, light weight, low power consumption, and its use as an information display device such as mobile phones, PDAs, personal computers, and televisions. It is expanding year by year.

As shown in FIG. 5, the general liquid crystal display element 41 provided in the liquid crystal display device includes a liquid crystal cell 42 in which the liquid crystal layer 44 is sandwiched by double-sided transparent medium layer 43 (for example, glass). And the polarizing plate 45 bonded to both surfaces of the liquid crystal cell 42 by the adhesive layer 48. The polarizer protective film 46 is bonded to this polarizing plate 45 on both surfaces of the polarizer 47 which has polarizing ability, and is comprised. In this manner, the polarizer 47 is protected by the polarizer protective film 46 from the viewpoint of improving the strength and facilitating handling.

Generally as a raw material of a polarizer, the PVA film which consists of polyvinyl alcohol which is hydrophilic resin is used. A polarizer is formed by uniaxially stretching a PVA film, dyeing with iodine or a dichroic dye, or stretching after dyeing, and then crosslinking with a boron compound.

As a polarizer protective film, it is generally triacetyl cellulose (TAC) from the point which requires an optically transparent and small retardation value, the surface is smooth, and the adhesiveness with the polarizer which consists of PVA is excellent. What has a base material layer which consists of is used. The triacetyl cellulose is saponified by alkali (converted into a hydroxyl group in which the ester group is a hydrophilic group), and then adhered to the polarizer composed of polyvinyl alcohol, which is a hydrophilic resin, using a water-soluble adhesive. However, since triacetyl cellulose is expensive, development of inexpensive alternative materials having equivalent properties is required.

In view of such circumstances, the present applicant has devised a polarizer protective film having a base layer made of acrylic resin or the like (see JP 2010-181500 A). When the polarizer protective film of this Unexamined-Japanese-Patent No. 2010-181500 uses a water-soluble adhesive by arranging a primer layer in one surface of a base material layer, and arranging a hydrophilic resin layer in one surface of a primer layer. The adhesiveness with the polarizer of is improved. In addition, it is assumed that the polarizer protective film of the said publication is mainly arrange | positioned at the outer surface side (side away from a liquid crystal cell, ie, the uppermost layer and the lowest layer in FIG. 5) of a liquid crystal display element.

On the other hand, it is said that it is preferable that the polarizer protective film arrange | positioned at the inner surface side of a liquid crystal display element is lower than the polarizer protective film arranged at the outer surface side of a liquid crystal display element. That is, when the retardation value of a polarizer protective film is high, the light ray which passed the polarizer and became linearly polarized light becomes an elliptical polarization by a polarizer protective film, and enters a liquid crystal layer, or the linearly polarized light which passed the liquid crystal layer by a polarizer protective film By becoming elliptical polarization, there is a possibility that the light beam cannot be sufficiently used for display. For this reason, it is desired that the polarizer protective film arrange | positioned at the inner surface side of a liquid crystal display element has a low retardation value as mentioned above.

However, since the base layer made of the conventional triacetyl cellulose has high moisture permeability and water absorption, it is easy to cause a dimensional change in a high humidity environment, and therefore, another layer (for example, an adhesive layer) or the like incorporated in the base layer is also a base layer. A change in the dimensionality is caused by a change in the size of the layer, and a photoelastic effect (change in the retardation value due to deformation) due to the change in the size of the other layer and the base layer is generated, and as a result, the light of the light source is not sufficiently used for display. It may cause a situation.

In order to solve such a problem, it is thought that the change of retardation value is suppressed by reducing a water absorptivity and a photoelastic coefficient by employ | adopting means using acrylic resin, cycloolefin resin, etc. as a base material layer as described in the said publication. do. However, in the case of adopting such a means, if the absorbency of the polarizer protective film is made too small, the moisture permeability is too small, and when the polarizer protective film is adhered to the polarizer with a water-soluble adhesive, moisture contained in the water-soluble adhesive does not evaporate correctly. There is no fear. Moreover, even if only the photoelastic coefficient of a base material layer is small, if moisture permeability is too high, water absorption will also become high and there exists a possibility of generating the photoelastic effect mentioned above by the dimensional change by humidity.

Japanese Unexamined Patent Publication No. 2010-181500

This invention is made | formed in view of such a situation, The polarizer protective film which can carry out adhesion easily and reliably with a polarizer by a water-soluble adhesive, reducing the dimensional change by humidity, and suppressing the change of retardation value, This It aims at providing the polarizing plate using a polarizer protective film, and the liquid crystal display element using this polarizing plate.

The invention made to solve the above problems,

As a polarizer protective film adhere | attached on the polarizer of a liquid crystal display panel,

A base layer containing acrylic resin as a main component,

1st control layer laminated | stacked on one surface side of this base material layer, and for controlling moisture permeability,

The adhesion easy layer laminated | stacked on one surface side of a 1st control layer,

2nd control layer laminated | stacked on the other surface side of a base material layer, and for controlling moisture permeability

And,

A 1st control layer and a 2nd control layer contain the same resin as a main component, It is a polarizer protective film characterized by the above-mentioned.

Since the said adhesive layer is arrange | positioned at one surface side of the said polarizer protective film, this adhesive layer and a polarizer can be reliably adhere | attached by a water-soluble adhesive agent. Moreover, the said polarizer protective film is formed by being controlled by the 1st control layer and the 2nd control layer arrange | positioned on both surfaces of a base material layer to desired moisture permeability, and for this reason, the moisture of a water-soluble adhesive at the time of adhesion | attachment with the said water-soluble adhesive is precisely formed. It can evaporate and the said bonding process can be performed easily and reliably. Moreover, since the main component of the said polarizer protective film is an acrylic resin, the dimension change of the base material layer under high humidity is less than a triacetyl cellulose, and a photoelastic effect hardly arises. For this reason, the change of the retardation value of the said polarizer protective film is small. In particular, in the polarizer protective film, since the second control layer is arranged on the other surface side of the substrate layer and is controlled and formed with desired moisture permeability, the dimensional change of the substrate layer is further suppressed and the dimensional change of the substrate layer is made smaller. The change in retardation value is small.

As for the said polarizer protective film, the said 1st control layer should just be thickness substantially the same as a 2nd control layer. Thereby, generation | occurrence | production of the curl in the case of manufacture can be prevented.

As for the said polarizer protective film, the said 2nd control layer should just be substantially thicker than a 1st control layer. Thereby, the curl prevention function with respect to the force which tries to become round can be provided by making an adhesion | attachment easy layer side inside, and generation | occurrence | production of the curl of the said polarizer protective film whole can be prevented. As a result, the polarizer protective film can improve dimensional stability.

The photoelastic coefficient of the said acrylic resin should just be -5 * 10 <^-12> / Pa or more and 5 * 10 <^-12> / Pa or less of the said polarizer protective film. By making the photoelastic coefficient of acrylic resin into the said range, the said polarizer protective film can make small the change of the retardation value of the base material layer by this dimensional change, even if a dimensional change generate | occur | produces.

As for the said polarizer protective film, the said easily bonding layer should just contain cellulose ester-type resin as a main component. Thereby, it can improve remarkably with the adhesiveness using the water-soluble adhesive of the polarizer which consists of polyvinyl alcohol, and an easily bonding layer. That is, since the hydroxyl group which is a hydrophilic group generate | occur | produces by saponifying an adhesive easy layer which contains a cellulose-ester type resin as a main component with alkali, a water-soluble adhesive can easily and reliably adhere | attach a cellulose resin and polyvinyl alcohol which is a hydrophilic resin. have.

The number average molecular weight (Mn) of the cellulose-ester type resin which the said easily bonding layer contains as a main component of the said polarizer protective film should just be 40000-100000. This can prevent the cellulose-ester-based resin from whitening and lowering of transparency when the adhesive easy layer is saponified with alkali while increasing the coating property of the adhesive easy layer.

As for the said polarizer protective film, the said 1st control layer and the 2nd control layer should just contain acrylic modified polyester resin as a main component. Thus, the adhesiveness to the adhesive easy layer is modified by acrylic modification while utilizing the properties such as transparency, toughness, heat resistance, and adhesiveness to the acrylic resin contained as a main component of the base material layer. It can be given.

As for the said polarizer protective film, the said 1st control layer and the 2nd control layer should just contain the said acrylic modified polyester-type resin and urethane-type resin. Thus, the adhesiveness to the adhesive easy layer is modified by acrylic modification while utilizing the properties such as transparency, toughness, heat resistance, and adhesiveness to the acrylic resin contained as a main component of the base material layer. In addition, the urethane resin can be blended to further provide adhesion and flexibility to the substrate layer and the adhesive easy layer.

The polarizer protective film may have a water vapor transmission rate of 1 g / m ² · 24 h or more and 250 g / m ² · 24 h or less. Thereby, the water of the water-soluble adhesive can be evaporated more accurately at the time of adhesion with the water-soluble adhesive, and the bonding layer and the polarizer can be attached more easily and reliably. Moreover, the said polarizer protective film can suppress suitably the dimensional change of a base material layer, and can make the change of the retardation of a base material layer further smaller.

The retardation value Re of the said base material layer should just be -15 nm or more and 15 nm or less of the said polarizer protective film. Thereby, in addition to the high dimensional stability which the said polarizer protective film has, the influence of the said polarizer protective film can be suppressed with respect to the optimization and controllability of the polarization of a polarized light toward the transmission axis direction in addition to suppressing the conversion effect of a transmission light ray. have.

Moreover, the polarizing plate made in order to solve the said subject,

The polarizer protective film,

Polarizer adhere | attached by the water-soluble adhesive to the easily bonding layer of this polarizer protective film

It is a polarizing plate provided with.

The polarizing plate of the polarizer protective film is easily bonded to the bonding layer and the polarizer by a water-soluble adhesive. In addition, since the polarizer protective film is controlled and formed by the first control layer and the second control layer in desired moisture permeability, the water of the water-soluble adhesive can be evaporated accurately at the time of adhesion by the water-soluble adhesive, and thus the adhesion process can be performed. It can be performed easily and reliably. As a result, the said polarizing plate can reliably adhere | attach a polarizer protective film and a polarizer. Moreover, since the main component of the base material layer of the said polarizer protective film is acrylic resin, the dimensional change of the base material layer under high humidity is less than triacetyl cellulose, and a photoelastic effect hardly arises. For this reason, the change of the retardation value of the said polarizer protective film is small. In particular, in the polarizer protective film, since the second control layer is arranged on the other surface side of the base layer and is controlled and formed with desired moisture permeability, the dimensional change of the base layer can be further suppressed to make the dimensional change of the base layer smaller. Can be. Therefore, the said polarizing plate can make small change of the retardation value of the said polarizer protective film, and can exhibit desired optical characteristic.

Moreover, the liquid crystal display element made in order to solve the said subject,

With a liquid crystal cell,

The said polarizing plate laminated | stacked on one surface side of this liquid crystal cell

It is a liquid crystal display element provided with.

The liquid crystal display element is reliably adhere | attached with the water-soluble adhesive and the easily bonding layer of a polarizer protective film. In addition, since the polarizer protective film is controlled and formed by the first control layer and the second control layer in desired moisture permeability, the water of the water-soluble adhesive can be evaporated accurately at the time of adhesion by the water-soluble adhesive, and thus the adhesion process can be performed. It can be done easily and accurately. As a result, the said liquid crystal display element can reliably adhere | attach a polarizer protective film and a polarizer. Moreover, since the main component of the base material layer of the said polarizer protective film is acrylic resin, the dimensional change of the base material layer under high humidity is less than triacetyl cellulose, and a photoelastic effect hardly arises. For this reason, the change of the retardation value of the said polarizer protective film is small. In particular, in the polarizer protective film, since the second control layer is arranged on the other surface side of the base layer and is controlled and formed with desired moisture permeability, the dimensional change of the base layer can be further suppressed to make the dimensional change of the base layer smaller. Can be. Therefore, the said liquid crystal display element can make small the change of the retardation value of the said polarizer protective film, and can exhibit desired optical characteristic. Therefore, the said liquid crystal display element can perform accurate display using the light of a light source effectively.

In addition, in this invention, "the same resin" includes the thing of the same chemical species in which the monomers which comprise are different, the composition differs, and the thing of which a polymerization form differs. "Photoelastic coefficient" is a coefficient which shows the tendency of the change of the refractive index by external force to generate | occur | produce, and is a value calculated | required by _CR [Pa- ¹ ] = (DELTA) n / (sigma) _R. Here, sigma _R is elongation stress [Pa], Δn is the refractive index difference at the time of stress addition, Δn is defined by the following equation.

Δn = n ₁ -n ₂

(Wherein n ₁ is the refractive index in the direction parallel to the stretching stress and n ₂ is the refractive index in the direction perpendicular to the stretching direction.)

"Water vapor transmission rate" is the value which measured the number of g of water vapor which passes the sample of 1 m <^2> in 24 hours in the atmosphere of temperature 40 degreeC and 92% RH of humidity according to the moisture permeability test (Cup method) of JISZ0208. In addition, "retardation value (Re)" is the x-axis and y-direction, the thickness of the polarizer protective film in the x-direction and y-direction, the orthogonal axis direction and the slow-axis direction orthogonal among the crystallographic directions on the plane of the polarizer protective film surface, d, x direction and y The refractive index of the direction is set to nx and ny (nx ≠ ny), and the value calculated by Re = (ny-nx) d is said.

As explained above, the polarizer protective film of this invention, the polarizing plate using this polarizer protective film, and the liquid crystal display element using this polarizing plate make the dimensional change of the base material layer of the said polarizer protective film by humidity small, and the While suppressing the change of the retardation value, the adhesion between the polarizer protective film and the polarizer by the water-soluble adhesive can be easily and reliably performed.

BRIEF DESCRIPTION OF THE DRAWINGS It is typical sectional drawing which shows the polarizer protective film which concerns on one Embodiment of this invention.
It is typical sectional drawing which shows the polarizing plate provided with the polarizer protective film of FIG.
FIG. 3 is a schematic diagram illustrating an apparatus for manufacturing the polarizing plate of FIG. 2.
4 is a schematic cross-sectional view illustrating a liquid crystal display device including the polarizing plate of FIG. 2.
It is a schematic diagram which shows the structure of the conventional general liquid crystal display element.

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

[First Embodiment]

The polarizer protective film 1 of FIG. 1 has the base material layer 2 which has acrylic resin as a main component, the 1st control layer 3 for controlling moisture permeability, the easily bonding layer 4, and for controlling moisture permeability The second control layer 5 is provided. The polarizer protective film 1 is formed as a laminated body in which the second control layer 5, the base material layer 2, the first control layer 3, and the adhesive easy layer 4 are arranged in this order. The polarizer protective film 1 is adhered to the polarizer of the liquid crystal display element from the side of the adhesive layer 4, and is a protective film for improving the impact resistance and handleability of this polarizer.

(Base layer (2))

As a main component of the base material layer 2, acrylic resin which is a synthetic resin which maintains high transparency required as a polarizer protective film of a liquid crystal display element, and has a constant moisture permeability is used. Although the base material layer 2 may also contain another arbitrary component unless it impairs transparency and desired intensity | strength, Preferably it contains 90 mass% or more of acrylic 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 remover, an antibacterial agent, an antifungal agent, etc. are mentioned.

Acrylic resin used as a main component of the base material layer 2 is resin which has frame | skeleton derived from acrylic acid or methacrylic acid. Examples of the acrylic resin include, but are not limited to, poly (meth) acrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methacrylic acid methyl- (meth) (Meth) acrylic acid ester-methacrylic acid copolymer, a (meth) acrylic acid methyl-styrene copolymer, a polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methacrylic acid Methyl (meth) acrylate norbornyl copolymer). 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.

Although it does not specifically limit as a photoelastic coefficient of the said acrylic resin, It is preferable that they are -5 * 10 <^-12> / Pa or more and 5 * 10 <^-12> / Pa or less. The upper limit value of the photoelastic coefficient of the acrylic resin is 4 × 10 ^-12 / Pa is more preferred, and more preferably 3 × 10 ^-12 / Pa. On the other hand, the lower limit of the photoelastic coefficient of the acrylic resin is more preferably -4 x 10 ^-12 / Pa, and more preferably -3 x 10 ^-12 / Pa. When the photoelastic coefficient of the said acrylic resin is out of the said range, there exists a possibility that the change of the retardation value at the time of a dimensional change arises may become large.

Although it does not specifically limit as water absorption of the said acrylic resin, 1.0% or less is preferable, 0.7% or less is more preferable, 0.5% or less is further more preferable. When the absorptivity of the said acrylic resin exceeds the said range, there exists a possibility that a dimensional change will generate | occur | produce when containing moisture evaporates. In addition, water absorption is based on the value measured using the film-shaped sample of 50 mm in width and 100 micrometers in thickness based on JISK7209.

Although it does not specifically limit as thickness (average thickness) of the base material layer 2, 10 micrometers or more and 200 micrometers or less are preferable. 100 micrometers is more preferable and, as for the upper limit of the thickness of the base material layer 2, 80 micrometers is more preferable. On the other hand, 20 micrometers is more preferable and 40 micrometers of the lower limit of the thickness of the base material layer 2 is more preferable. When the thickness of the base material layer 2 exceeds the said upper limit, there exists a possibility that the line speed at the time of manufacture, productivity, and moisture permeability may fall, and it may be against the request of thickness reduction of a liquid crystal display device. On the contrary, when the thickness of the base material layer 2 is less than the said lower limit, intensity | strength and rigidity become small, and there exists a possibility that handling may become difficult in a manufacturing line.

Although it does not specifically limit as arithmetic mean surface roughness Ra of the base material layer 2, Usually, what is 0.02 or more and 0.06 or less can be used. Moreover, the mat process can be performed to the base material layer 2 as needed. 2 is preferable and, as for the upper limit of the arithmetic mean surface roughness Ra of the base material layer 2 which performed this mat process, 1 is more preferable. On the other hand, 0.07 is preferable and, as for the lower limit of the arithmetic mean surface roughness Ra of the base material layer 2 which performed the mat process, 0.1 is more preferable. By controlling the arithmetic mean surface roughness Ra of the base material layer 2 which has been subjected to the mat treatment in such a range, the occurrence of scratches in the treatment after film master fabrication is prevented and the handleability is improved. Moreover, generally, when winding up the produced film original fabric, it is preferable to prevent blocking by embossing (knurling process) the both ends of the width direction of a film. In the case where the film is knurled, the treated portions of both ends of the film cannot be used, so the part must be cut and discarded. Moreover, in the winding operation of a film, masking may be performed by a protective film in order to prevent a wound generation. However, by making the arithmetic mean surface roughness Ra of the base material layer 2 into the said range, blocking can be prevented without performing a knurling process, and a manufacturing process is simplified and both ends of a film width direction can also be used. In addition, it can wind up for a long time without generating the malfunction of a film. Moreover, since the base material layer 2 has a suitable surface roughness, the wound generation at the time of winding is suppressed effectively, and the above masking becomes unnecessary.

Although it does not specifically limit as retardation value Re of the base material layer 2, It is preferable that they are -15 nm or more and 15 nm or less. 10 nm is more preferable, and, as for the upper limit of the retardation value Re of the base material layer 2, 5 nm is still more preferable. On the other hand, as for the lower limit of the retardation value Re of the base material layer 2, -10 nm is more preferable, and -5 nm is still more preferable. When the retardation value Re of the base material layer 2 is out of the said range, there exists a possibility that optimization of the polarization to the transmission axis direction of a polarizer may not be attained by the conversion action of the polarization direction of a transmission light ray.

Although the manufacturing method of the base material layer 2 is not specifically limited, For example, additives, such as a flake raw material of acrylic 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 manufactured. can do. This thermoplastic resin composition is obtained by, for example, preblending with a mixer such as an omnimixer and then extrusion kneading the obtained mixture. In this case, the kneading machine used for extrusion kneading is not particularly limited, and for example, a conventionally known kneading machine such as an extruder such as a single screw extruder or a twin screw extruder or a pressure 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. At this time, the thermoplastic resin composition kneaded in advance may be used, and other additives such as a synthetic resin and a plasticizer are dissolved separately in a solvent to form a uniform mixed solution, and then 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-type solvents, such as chloroform and dichloromethane; Aromatic solvents, such as toluene, xylene, benzene, and these mixed solvents; Methanol, ethanol, isopropanol, alcohol solvents such as 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; And the like. These solvents may be used alone or in combination of two or more. 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. Preferably the shaping | molding temperature of the film at the time of melt extrusion is 150 degreeC or more and 350 degrees C or less, More preferably, they are 200 degreeC or more and 300 degrees C or less. When film-forming by the 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, the uniaxial stretching process can be also carried out by appropriately adjusting the temperature of the take-up roll and stretching in the extrusion direction. Moreover, it is also possible to add processes, such as sequential biaxial stretching and simultaneous biaxial stretching, by adding the process of extending | stretching a film to a direction perpendicular | vertical to an extrusion direction.

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. When using a biaxially stretched film, it may be simultaneous biaxially stretched, and may be a biaxially stretched one by one. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved.

As extending | stretching temperature in the case 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. When extending | stretching temperature exceeds the said upper limit, there exists a possibility that flow (flow) of resin may arise and it may become impossible to perform stable extending | stretching. On the contrary, when extending | stretching temperature is less than the said lower limit, there exists a possibility that sufficient draw ratio may not be obtained.

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 a draw ratio exceeds the said upper limit, there exists a possibility that the effect of raising draw ratio may not be confirmed. On the other hand, when the draw ratio is less than the said lower limit, there exists a possibility that it may not lead to the improvement of toughness by extending | stretching.

As a drawing speed (one direction), Preferably it is the range of 10-20000% / min, More preferably, it is the range of 100-10000% / min. When the stretching speed exceeds the above upper limit, breakage of the stretched film may occur. On the other hand, when the stretching speed is lower than the lower limit value, it takes time to obtain a sufficient stretching magnification, which may increase the manufacturing cost. In addition, in order to stabilize the optical isotropy and the dynamics characteristic of the base material layer 2, you may perform heat processing (annealing) etc. after an extending | stretching process.

Although it does not specifically limit as said 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, phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol plasticizers, glycolate plasticizers, citric acid ester plasticizers, and fatty acid ester compounds. A plasticizer, a carboxylic acid ester plasticizer, a polyester plasticizer, etc. are mentioned.

(First control layer 3)

The first control layer 3 is laminated on one surface side of the base material layer 2. As a main component of the 1st control layer 3, hydrophilic resin is used suitably. Although it does not specifically limit as this hydrophilic resin as long as it is resin which has chemical affinity with the base material layer 2 and the easily bonding layer 4, It is preferable that the side chain is modified by the group which has hydrophilicity. As a method of hydrophilic modification of hydrophilic resin, the monomer which has a hydrophilic functional group may be previously (co) polymerized, or after (co) polymerizing the monomer used as a main chain, the monomer which has a hydrophilic group may be graft-polymerized, and a side chain may be formed. do. Moreover, it is preferable that this hydrophilic resin is formed from what is chosen from the group which consists of polyester resin, acrylic resin, urethane resin, and epoxy resin. These resins may be a polymerization or a copolymerization of two or more kinds alone. As hydrophilic resin, what has a weight average molecular weight of 300 or more and 30000 or less can be used, for example.

The polyester resin contained as a main component of the first control layer 3 is produced by esterifying (ester exchange) and dicondensing dicarboxylic acid and diol according to a known method. Examples of the dicarboxylic acid include aromatic dicarboxylic acids or esters thereof such as terephthalic acid, isophthalic acid, phthalic acid and naphthalinic dicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, succinic acid, sebacic acid and dodecane diacid. Acids, hydroxycarboxylic acids such as hydroxybenzoic acid or esters thereof can be used. As the diol, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, bisphenols and the like can be used.

As said polyester-type resin, in addition to the dicarboxylic acid and diol mentioned above, it is preferable to copolymerize the component which has a hydrophilic group, and to give hydrophilicity. As an example of the component which has such a hydrophilic group, dicarboxylic acid components, such as 5-sodium sulfoisophthalic acid, and diol components, such as diethylene glycol, triethylene glycol, and polyethylene glycol, are mentioned. The component which has these hydrophilic groups can be used in the ratio of 2 mol% or more and 80 mol% or less with respect to the dicarboxylic acid or diol mentioned above, for example. The component which comprises these polyester-based resin can be used individually or in combination of multiple types.

Acrylic resin contained as a main component of the first control layer 3 can be synthesized by polymerizing a reactive polymer having a skeleton derived from acrylic acid or methacrylic acid. Examples of such reactive polymers include those having carboxyl groups such as acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, and carboxyphenyl acrylate, 2-hydroxyethyl (meth) acrylate, and 3-hydroxybutyl (meth) acrylic. Having hydroxyl groups, such as the rate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxypropyl (meth) acrylate, (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth ) Having amide groups, such as acrylamide, N, N-dimethyl (meth) acrylamide, and N-methylol (meth) acrylamide, Having glycidyl groups, such as glycidyl (meth) acrylate, 7- P-chlorostyrene, chloromethylstyrene, divinylbenzene, 4-vinylpyridine, in addition to having amino groups such as amino-3,7-dimethyloctyl (meth) acrylate and 2-dimethylaminoethyl (meth) acrylate; Vinyloxazoline, Number and the like can be mentioned maleic acid.

Examples of the copolymer components other than those constituting the acrylic resin include acrylic acid esters, methacrylic acid esters, propylene, vinyl chloride, cellulose, ethylene, ethyleneimine, vinyl alcohol, peptide, vinylpyridine, Although diene type, a fluorine type, an acrylonitrile type, etc. are mentioned, It is preferable to contain an acrylic ester type and a methacrylic acid ester type from a viewpoint of versatility, coating property, etc. The component which comprises these acrylic resin can be used individually or in combination of multiple types.

The urethane resin contained as a main component of the first control layer 3 can be synthesized from a low molecular weight chain extender containing at least two hydrogen atoms reacting with a polyhydroxyl compound, diisocyanate and diisocyanate by a known method. have. For example, after synthesizing a relatively high molecular weight polyurethane in a solvent, a small amount of water is added to the phase to emulsify, and a solvent is removed under reduced pressure, or a urethane prepolymer in which polyethylene glycol or a carboxyl group is introduced as a hydrophilic group in a polymer. After dissolving or dispersing in water, a chain extender is added and reacted.

Examples of the polyhydroxyl compound used in the production of the urethane-based resin include carboxylic acids such as phthalic acid, adipic acid, dimerized linoleic acid and maleic acid; glycols such as ethylene glycol, propylene glycol, butylene glycol, and diethylene glycol. Polyester polyols obtained by dehydration condensation from trimethylolpropane, hexanetriol, glycerin, trimethylolethane, pentaerythritol, and the like; polyoxypropylene glycol, polyoxybutylene glycol, polytetramethylene glycol, polyoxy Polyether polyols, such as polyoxypropylene polyol and polyoxypropylene polyoxyethylene polyol which used inorganic acids, such as propylene triol, polyoxyethylene polyoxypropylene triol, sorbitol, pentaerythritol, sucrose, starch, and phosphoric acid as an initiator, Acryl polyols, derivatives of castor oil, tall oil derivatives, other hydroxyl group compounds, and the like. The can. These polyhydroxyl compounds can be used individually or in combination of multiple types.

Examples of the diisocyanate used in the production of the urethane-based resins include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylenedi isocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate , Tetramethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, lidin diisocyanate, isophorone diisocyanate, trimethyl hexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4'-dicyclohexyl methane Diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate, 3,3'-dichloro-4,4'- Biphenylene diisocyanate, 1, 5- naphthalene diisocyanate, 1, 5- tetrahydro naphthalene diisocyanate, etc. are mentioned. These diisocyanate can be used individually or in combination of multiple types.

Examples of the chain extender used in the preparation of the urethane-based resin include ethylene glycol, 1,4-butanediol, trimethylolpropane, triisopropanolamine, N, N-bis (2-hydroxypropyl) aniline, hydroquinone-bis (β-hydride) Polyols such as oxyethyl) ether and resorcinol-bis (β-hydroxyethyl) ether, ethylenediamine, propylenediamine, hexamethylenediamine, phenylenediamine, tolylenediamine, diphenyldiamine, diaminodiphenylmethane And polyamines such as diaminodiphenylmethane, diaminodicyclohexylmethane, piperazine, isophoronediamine, diethylenetriamine and dipropylenetriamine, hydrazines and water. These chain extenders can be used individually or in combination of multiple types.

The synthesis reaction in the production of the urethane-based resin can be carried out in the presence of a catalyst such as an organic tin compound, organic bismuth, or an amine, and it is particularly preferable to carry out in the presence of an organic tin compound. Specific examples of the organic tin compound include first tin carboxylic acids such as first tin acetate, first tin octanoate, first tin laurate, and first tin oleate; dibutyltin acetate, dibutyltin dilaurate, and di Dialkyl tin salts of carboxylic acids such as butyltin maleate, dibutyltin di-2-ethylhexate, dilauryl tin diacetate, and dioctyl tin diacetate; trimethyl tin hydroxide, tributyl tin hydroxide and trioctyl hydroxide Trialkyl tin hydroxides such as tin; dialkyl tin oxides such as dibutyltin oxide, dioctyl tin oxide, and dilauryl tin oxide; dialkyl tin chlorides such as dibutyltin chloride and dioctyltin chloride; In addition, these may be used individually by 1 type and may use 2 or more types together.

The epoxy resin contained as a main component of the first control layer 3 can be synthesized by polymerizing a monomer having an epoxy group. Examples of such monomers include glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether. As the monomer copolymerizable with these monomers, vinyl esters, unsaturated carboxylic acid esters, unsaturated carboxylic acid amides, unsaturated nitriles, allyl compounds, unsaturated hydrocarbons or vinylsilane compounds are used. Specific examples thereof include vinyl propionate, vinyl chloride, vinyl bromide, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, butyl maleate, octyl maleate and butyl fumarate , Octyl fumarate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, ethylene glycol dimethacrylate ester, ethylene glycol diacrylate ester, polyethylene glycol dimethacrylate ester , Polyethylene glycol diacrylic acid ester, acrylamide, methacrylamide, methylol acrylamide, butoxymethylol acrylamide, unsaturated nitrile acrylonitrile, allyl acetate, allyl methacrylate, allyl acrylate, diallyl itaconic acid, ethylene , Propylene, hexane, octene, styrene, vinyltoluene, butadiene, dimethylvinylmethoxysilane, dimeth Ethyl and the like silane, methyl vinyl dimethoxy silane, methyl vinyl diethoxy silane, γ- methacryloxypropyltrimethoxysilane trimethoxysilane, γ- methacryloxypropyltrimethoxysilane methyl dimethoxysilane. The component which comprises these epoxy resin can be used individually or in combination of multiple types.

In hydrophilic modification of hydrophilic resin, when (co) polymerizing the monomer used as a main chain, and graft-polymerizing a hydrophilic monomer to form a hydrophilic side chain, it is preferable to graft-polymerize a hydrophilic radically polymerizable vinyl monomer. In this case, 10 mass parts or more and 500 mass parts or less of radically polymerizable vinyl monomers can be used with respect to a total of 100 mass parts of a main chain component.

Examples of such hydrophilic radical polymerizable vinyl monomers include -CH ₂ -CH (R) -OH (wherein -R is -H or -CH ₃ ), -COOX (wherein X is H, an alkali metal or 2). -O- (CH ₂ -CH (R) -O) _n- ( _wherein -R is -H or -CH ₃ , n is a positive integer), -YN (R ₁ ) (R ₂ ) (-Y- is -C (= O)-or -CH _2- , -R ₁ , -R ₂ is -H, or hydroxyl group, sulfonyl group, acyl group, amino group, alkali Is a lower alkyl group which may have a metal salt or a quaternary ammonium salt), -N ⁺ -(R ₃ ) (R ₄ ) (R ₅ ) (wherein -R ₃ , -R ₄ , -R ₅ is -CH ₃ Or those having a hydrophilic group such as -C ₂ H ₅ ) and -CH ₂ -CH (O) CH ₂ (O forms an epoxy ring with carbon on both sides).

Specific examples of the hydrophilic radical polymerizable vinyl monomers include hydroxyacrylic acid esters such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate, ethylene glycol acrylate and ethylene glycol methacryl. Glycol esters, such as the rate, polyethyleneglycol acrylate, and polyethyleneglycol methacrylate, acrylamide type compounds, such as acrylamide, methacrylamide, methylol acrylamide, and methoxymethylol acrylamide, glycidyl acrylate, methacrylic acid Glycidyl acrylate compounds such as glycidyl, vinyl-containing compounds such as vinylpyridine, vinylimidazole, vinylpyrrolidone, acrylic acid, methacrylic acid, maleic anhydride, itaconic acid and crotonic acid Unsaturated acids and salts thereof, aminoalkyl acrylates, aminoalkyl methacrylates and their And cationic monomers such as quaternary ammonium salts.

In hydrophilic modification of the said hydrophilic resin, in addition to these radically polymerizable vinyl monomers, you may copolymerize another vinyl monomer. Examples of other copolymerizable vinyl monomers include vinyl esters such as vinyl acetate and vinyl propionate; vinyl halides such as vinyl chloride and vinyl bromide; methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate. Unsaturated carboxylic acid esters; vinyl silanes such as dimethyl vinyl methoxysilane and γ-methacryloxypropyl trimethoxy silane; and olefins and diolefin compounds such as ethylene, propylene, styrene and butadiene.

When polyester-based resin is used as a main component of the first control layer 3, as the polyester-based resin, a radical polymerizable vinyl monomer derived from acrylic acid having a hydrophilic group (hereinafter referred to as an "acrylic radical polymerizable vinyl monomer") It is most preferable to use polyester-based resin (hereinafter, referred to as "acrylic-modified polyester-based resin") in which side chains are modified. By using an acrylic modified polyester resin as a main component of the first control layer 3, the transparency, toughness, heat resistance, and synthetic resin (for example, an acrylic system that is the main component of the base material layer 2) that the polyester resin originally has The adhesiveness to the adhesion bonding layer 4 can be provided by the said modifying machine, while utilizing characteristics, such as adhesiveness with respect to resin etc.). Moreover, as the 1st control layer 3, the composition containing a urethane resin with the said acrylic modified polyester resin contained as a main component is the most preferable. By using the composition containing acrylic modified polyester resin and urethane resin as a main component of the 1st control layer 3, characteristics, such as transparency, toughness, heat resistance, adhesiveness with respect to a synthetic resin, which a polyester resin originally has, etc. In addition to providing the adhesiveness to the adhesive layer 4 by the modifying group, the adhesive and flexibility of the base layer 2 and the adhesive layer 4 can be further improved by the blend of the urethane resin. It becomes possible to give.

The weight average molecular weight of the said acrylic radically polymerizable vinyl monomer and urethane type resin is typically 1000 or more and 15000 or less, Preferably it is 2000 or more and 10000 or less.

The mass of the urethane resin in the composition is preferably 10% or more and 70% or less, and more preferably 25% or more and 40% or less with respect to the mass of the acrylic modified polyester resin. By setting the mass ratio of the acrylic modified polyester resin and the urethane resin in such a range, the base material layer 2 and the adhesive easy layer (while maintaining the physical properties such as transparency, water resistance and heat resistance of the first control layer 3 satisfactorily) It becomes possible to optimize the adhesion for 4).

As a hydrophilic group which the acrylic radical polymerizable vinyl monomer which is a modified component of the said acrylic modified polyester resin has, the thing illustrated as a hydrophilic group of said hydrophilic radical polymerizable vinyl monomer can be used. That is, the representative hydrophilic groups of the acrylic radical polymerizable vinyl monomers include -CH ₂ -CH (R) -OH, -COOX, -O- (CH ₂ -CH (R) -O) _n- , and -YN (R ₁ ). (R ₂ ), -N ⁺ -(R ₃ ) (R ₄ ) (R ₅ ), -CH ₂ -CH (O) CH ₂ (definition is as described above).

As said acrylic radically polymerizable vinyl monomer, the acrylic monomer mentioned as a specific example of said hydrophilic radically polymerizable vinyl monomer can be used. That is, specific examples of the acrylic radical polymerizable vinyl monomer include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, ethylene glycol acrylate, ethylene glycol methacrylate, and polyethylene glycol acrylate. , Polyethylene glycol methacrylate, acrylamide, methacrylamide, methylol acrylamide, methoxymethylol acrylamide, glycidyl acrylate, glycidyl acrylate, acrylic acid, methacrylic acid, aminoalkyl acrylate, methacrylic Acid aminoalkyl ester etc. are mentioned. These acrylic radical polymerizable vinyl monomers may be used independently, or may be used in combination of multiple types.

Moreover, what copolymerized the above-mentioned other copolymerizable vinyl monomer in addition to an acryl-type radical polymerizable vinyl monomer can also be used for the said acrylic modified polyester resin. When copolymerizing another vinyl monomer, 1 mass part or more and 70 mass parts of other vinyl monomers can be used with respect to 100 mass parts of acrylic radical polymerizable vinyl monomers, for example.

In the said acrylic modified polyester resin, 50 mass parts or more and 150 mass parts or less of the mass ratio of the acrylic radical polymerizable vinyl monomer with respect to the polyester resin which forms a main chain are preferable with respect to 100 mass parts of polyester resins, It is more preferable to set it as 70 mass parts or more and 120 mass parts or less. By setting the mass ratio of the acrylic radical polymerizable vinyl monomer to the polyester resin in such a range, the chemical affinity for the base layer 2 of the first control layer 3 and the layer for bonding the first control layer 3 It is possible to improve the chemical affinity for (4) in a good balance.

The acrylic modified polyester resin is, for example, an aqueous solution containing a water-soluble or water-dispersible polyester resin copolymerized with a component having a hydrophilic group such as a dicarboxylic acid component such as 5-sodium sulfoisophthalic acid and a polyvinyl alcohol, or It can be prepared by preparing an aqueous dispersion and then copolymerizing an acrylic radical polymerizable vinyl monomer (and any other copolymerizable vinyl monomer).

In the manufacturing method of acryl-modified polyester-type resin using the said polyvinyl alcohol, For example, the ratio of 10 mass parts or more and 500 mass parts or less of polyvinyl alcohol with respect to 100 mass parts of water-soluble or water-dispersible polyester (solid content ratio) Reaction).

As a polymerization method for synthesizing the acrylic modified polyester resin, for example, a small amount of emulsifying dispersant may be used in an aqueous solution or an aqueous dispersion of the water-soluble or water-dispersible polyester and polyvinyl alcohol. A method of completing the polymerization reaction is added by gradually adding the acrylic radical polymerizable vinyl monomer while stirring and aging for several hours while maintaining the temperature at about 70 ° C.

As a polymerization initiator used for manufacture of the said acrylic modified polyester resin, a general radical polymerization initiator can be used. Examples of the polymerization initiator include water-soluble peroxides such as potassium persulfate, ammonium persulfate and hydrogen peroxide, oil-soluble peroxides such as benzoyl peroxide and t-butyl hydroperoxide, and azo compounds such as azodiisobutyronitrile.

Although it does not specifically limit as thickness (average thickness) of the 1st control layer 3, It is preferable that they are 0.01 micrometer or more and 5 micrometers or less. 4 micrometers is more preferable, and, as for the upper limit of the thickness of the 1st control layer 3, 3 micrometers is more preferable. On the other hand, 0.04 micrometer is more preferable and, as for the lower limit of the thickness of the 1st control layer 3, 1 micrometer is still more preferable. When the thickness of the 1st control layer 3 exceeds the said upper limit, the thickness of the polarizer protective film 1 may become thick and it may be against the request of thinning of a liquid crystal display device. On the contrary, when the thickness of the 1st control layer 3 is less than the said lower limit, there exists a possibility that formation of the 1st control layer 3 may become difficult.

The first is not particularly limited as the water vapor transmission rate of the control layer 3, preferably 1g / m ² · 24h or more 200g / m ² · 24h or less. As for the upper limit of the water vapor transmission rate of the 1st control layer 3, 130 g / m <^2> * 24h is more preferable, and 80 g / m <^2> * 24h is still more preferable. On the other hand, as for the lower limit of the water vapor transmission rate of the 1st control layer 3, 10 g / m <^2> * 24h is more preferable, and 20 g / m <^2> * 24h is still more preferable. When the water vapor transmission rate of the 1st control layer 3 exceeds the said upper limit, the ratio of the water which permeates from the outside becomes large, and there exists a possibility that the dimension change of the base material layer 2 etc. may arise. On the other hand, when the water vapor transmission rate of the 1st control layer 3 is less than the said lower limit, when the adhesive bonding layer 4 and a polarizer are adhere | attached with a water-soluble adhesive, it may need a long time to evaporate the water contained in this water-soluble adhesive. There is. In contrast, when the water vapor transmission rate of the first control layer 3 is within the above range, the moisture contained in the water-soluble adhesive is suitably evaporated to promote drying of the easy-adhesive layer 4, and In addition to improving the adhesiveness, the dimensional stability of the polarizer protective film 1 can be improved.

The 1st control layer 3 can be formed by apply | coating the aqueous emulsion or aqueous solution containing hydrophilic resin (henceforth "aqueous emulsion etc.") to the base material layer 2, and drying it. Solid content, such as aqueous emulsion, is 10 mass% or more and 50 mass% or less normally. Although water is used as main solvent, such as an aqueous emulsion, you may use a small amount of organic solvents miscible with water. Examples of such organic solvents include lower alcohols, polyhydric alcohols, alkyl ethers and alkyl esters thereof, and the like. Aqueous emulsion etc. are a base material layer (using the well-known dip coating method, the air knife coating method, the curtain coating method, the roller coating method, the wire bar coating method, the gravure coating method, the extrusion coating method (die coating method), etc. 2) can be applied. Next, the first control layer 3 can be formed by drying the applied aqueous emulsion or the like.

It is preferable to add a crosslinking agent as needed in an aqueous emulsion for forming the 1st control layer 3, etc. Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, active vinyl compounds, active halogen compounds, isoxazoles, dialdehyde starches, isocyanate compounds, and silane coupling agents. These crosslinking agents may be used independently or may use two or more types together. 0.1 mass% or more and 20 mass% or less are preferable with respect to hydrophilic resin whole quantity, and, as for the addition amount of a crosslinking agent, 0.5 mass% or more and 15 mass% or less are more preferable. The aqueous emulsion for forming the first control layer 3 may further contain other resin components such as amino group-containing resins, surfactants, lubricants, dyes, UV absorbers, matting agents, preservatives, thickeners, film preparations, and antistatic agents, if necessary. , Antioxidant and the like may be added.

(Easy Bonding Layer 4)

The easily bonding layer 4 is laminated on one surface side of the first control layer 3. The main component of the adhesive layer 4 is not particularly limited as long as it is a resin having chemical affinity with the hydrophilic resin included as the main component of the first control layer 3 and the polyvinyl alcohol constituting the polarizer. Resin is suitably used. When the adhesive easy layer 4 has cellulose ester type resin as a main component, the adhesiveness of the polarizer which consists of polyvinyl alcohol which is a hydrophilic resin, and the adhesive easy layer 4 improves remarkably. That is, by saponifying the easy-to-adhere layer (4) containing a cellulose ester-based resin as a main component with alkali, a hydrophilic group hydroxyl group is generated, whereby adhesion with polyvinyl alcohol as a hydrophilic resin is effectively improved. Therefore, the said polarizer protective film 1 can easily and reliably adhere | attach the easily bonding layer 4 and a polarizer using a water-soluble adhesive.

The cellulose ester-based resin included as the main component in the easy-to-adhesive layer 4 is not particularly limited as long as it is saponified with alkali to generate hydroxyl groups. However, 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 is increased, and can be reliably bonded.

Although it does not specifically limit as number average molecular weight (Mn) of the cellulose-ester type resin contained in the easily bonding layer 4 as a main component, It is preferable that it is 40000 or more and 100000 or less. 90000 are more preferable, and, as for the upper limit of the number average molecular weight (Mn) of the said cellulose ester-type resin, 80000 are still more preferable. On the other hand, 50000 is more preferable and, as for the lower limit of the number average molecular weight (Mn) of the said cellulose ester-type resin, 60000 are still more preferable. When the said number average molecular weight (Mn) exceeds the said upper limit, there exists a possibility that the coating property of the adhesion easily bonding layer 4 may fall. On the contrary, when the said number average molecular weight (Mn) is less than the said lower limit, when the adhesive easy layer 4 saponifies with alkali, a cellulose ester-type resin may whiten and transparency may fall.

Although it does not specifically limit as a value of ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose ester-type resin contained as a main component in the easily bonding layer 4, It is preferable that they are 1.4 or more and 3 or less. Do. As for the upper limit of the ratio (Mw / Mn) of the said weight average molecular weight (Mw) and number average molecular weight (Mn), 2.5 is more preferable and 2.1 is still more preferable. On the other hand, 1.6 is more preferable and, as for the lower limit of ratio (Mw / Mn) of the said weight average molecular weight (Mw) and number average molecular weight (Mn), 1.8 is still more preferable. When ratio (Mw / Mn) of the said weight average molecular weight (Mw) and number average molecular weight (Mn) exceeds the said upper limit, there exists a possibility that the dimensional stability of the easily bonding layer 4 may fall. On the contrary, when the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the said cellulose ester-type resin is less than the said minimum, there exists a possibility that manufacture of a desired cellulose ester may become difficult.

Although it does not specifically limit as thickness (average thickness) of the easily bonding layer 4, It is preferable that they are 0.01 micrometer or more and 5 micrometers or less. 4 micrometers is more preferable and, as for the upper limit of the thickness of the easily bonding layer 4, 3 micrometers is more preferable. On the other hand, 0.04 micrometer is more preferable and, as for the lower limit of the thickness of the easily bonding layer 4, 1 micrometer is still more preferable. When the thickness of the easily bonding layer 4 exceeds the said upper limit, the thickness of the polarizer protective film 1 may become thick and it may be against the request of thickness reduction of a liquid crystal display device. Moreover, when the thickness of the easily bonding layer 4 exceeds the said upper limit, there exists a possibility that the moisture permeability of the easily bonding layer 4 may fall. On the contrary, when the thickness of the easily bonding layer 4 is less than the said lower limit, there exists a possibility that the adhesiveness of the easily bonding layer 4 and the 1st resin layer 3 may fall. On the other hand, when the thickness of the easily bonding layer 4 is in the said range, the thickness of the polarizer protective film 1 can be kept thin, and the hydroxyl group which generate | occur | produced by saponifying the cellulose ester which comprises the easily bonding layer 4 is made. Bonding with the polyvinyl alcohol constituting the polarizer becomes more reliable.

Although the solvent of the coating liquid of cellulose ester for forming the easily bonding layer 4 will not be specifically limited if it is an organic solvent which melt | dissolves a cellulose ester sufficiently, For example, dioxane, acetone, methyl ethyl ketone, N, N-dimethyl Formamide, methyl acetate, ethyl acetate, trichloroethylene, methylene chloride, ethylene chloride, tetrachloroethane, trichloroethane, chloroform and the like are 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 easily bonding layer 4 as needed. In particular, a crosslinking agent is preferable in promoting 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 liquid of the cellulose ester for forming the easily bonding layer 4 can be apply | coated to the 1st control layer 3 using well-known methods, such as a gravure coater, a dip coater, a reverse roll coater, and an extrusion coater. 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. When the amount of residual solvent is large, bubbles may be generated at the adhesive interface in the drying process after laminating the polarizer protective film 1 to the polarizer, which is not preferable.

 (2nd control layer 5)

The second control layer 5 is laminated on the other surface side of the substrate layer 2. [ The second control layer 5 contains the same resin as the main component as the first control layer 3. The main component of the second control layer 5 is not particularly limited as long as it contains the same resin as the first control layer 3, but is preferably the same material as the main component of the first control layer 3. When the material for forming the main component of the second control layer 5 is the same as the material for forming the main component of the first control layer 3, the moisture permeability of the second control layer 5 and the first control layer 3 can be made closer. It is possible to control the moisture permeability of the whole polarizer protective film 1 more reliably. Moreover, when the formation material of the main component of the 2nd control layer 5 is the same as the formation material of the main component of the 1st control layer 3, the ease of manufacture of the said polarizer protective film 1 can be improved.

Moreover, although it does not specifically limit as thickness (average thickness) of the 2nd control layer 5, It is preferable that they are 0.01 micrometer or more and 5 micrometers or less. 4 micrometers is more preferable, and, as for the upper limit of the thickness of the 2nd control layer 5, 3 micrometers is more preferable. On the other hand, 0.04 micrometer is more preferable and, as for the lower limit of the thickness of the 2nd control layer 5, 1 micrometer is still more preferable. When the thickness of the 2nd control layer 5 exceeds the said upper limit, the thickness of the polarizer protective film 1 may become thick and it may be against the request of thickness reduction of a liquid crystal display device. On the contrary, when the thickness of the 2nd control layer 5 is less than the said lower limit, there exists a possibility that formation of the 2nd control layer 5 may become difficult.

The total thickness (average thickness) of the first control layer 3 and the second control layer 5 is not particularly limited, but is preferably 1.0 μm or more and 10 μm or less. As for the upper limit of the total thickness of the 1st control layer 3 and the 2nd control layer 5, 8 micrometers is more preferable and 6 micrometers is still more preferable. On the other hand, 2 micrometers is more preferable and, as for the lower limit of the total thickness of the 1st control layer 3 and the 2nd control layer 5, 3 micrometers is still more preferable. When the total thickness of the 1st control layer 3 and the 2nd control layer 5 exceeds the said upper limit, the thickness of the polarizer protective film 1 becomes thick, and it goes against the request of thinning of a liquid crystal display device, There is a risk that the moisture permeability decreases and a long time is required to evaporate the water contained in the water-soluble adhesive. On the contrary, when the total thickness of the 1st control layer 3 and the 2nd control layer 5 is less than the said lower limit, there exists a possibility that formation of the 1st control layer 3 and the 2nd control layer 5 may become difficult.

The thickness of the second control layer 5 is preferably substantially the same as the thickness of the first control layer 3. In the polarizer protective film 1, the thickness of the second control layer 5 is substantially the same as the thickness of the first control layer 3, whereby the first control layer 3 and the second control layer 5 are formed. The generation | occurrence | production of the curl in the state laminated | stacked on the base material layer 2 can be prevented, and also the ease of manufacture of the said polarizer protective film 1 can be improved.

The water vapor transmission rate of the second control layer 5 is not particularly limited, but is preferably 1 g / m ² · 24h or more and 200 g / m ² · 24h or less. As for the upper limit of the water vapor transmission rate of the 2nd control layer 5, 130 g / m <^2> * 24h is more preferable, and 80 g / m <^2> * 24h is still more preferable. On the other hand, the second lower limit of the water vapor transmission rate of the control layer 5 is 10g / m ² · 24h, and is more preferably, 20g / m ² · 24h is more preferred. When the water vapor transmission rate of the 2nd control layer 5 exceeds the said upper limit, the permeation rate of the moisture which exists outside becomes high, and there exists a possibility that the change of the dimension of the base material layer 2 etc. may arise. On the other hand, when the water vapor transmission rate of the 2nd control layer 5 is less than the said lower limit, the said polarizer protective film 1, such as water contained in this water-soluble adhesive, when the adhesive bond layer 4 and a polarizer are bonded by a water-soluble adhesive, etc. There is a possibility that a long time is required to evaporate the water contained therein.

The 2nd control layer 5 can be formed in the other surface side of the base material layer 2 by the method similar to the 1st control layer 3.

<Polarizer protective film 1>

As a water vapor transmission rate of the polarizer protective film 1, it is preferable that they are 1 g / m <^2> * 24h or more and 250 g / m <^2> * 24h or less. 150 g / m <^2> * 24h or less is more preferable, and, as for the upper limit of the water vapor transmission rate of the polarizer protective film 1, 100 g / m <^2> * 24h is still more preferable. On the other hand, as for the lower limit of the water vapor transmission rate of the polarizer protective film 1, 10 g / m <^2> * 24h is more preferable, and 20 g / m <^2> * 24h is still more preferable. When the water vapor transmission rate of the polarizer protective film 1 exceeds the said upper limit, the ratio of the water permeate | transmitted from the exterior will become high and there exists a possibility that the dimensional change of the base material layer 2, etc. may arise. On the contrary, when the water vapor transmission rate of the polarizer protective film 1 is less than the said lower limit, when the adhesive bonding layer 4 and a polarizer are adhere | attached with a water-soluble adhesive, there exists a possibility that it may require a long time to evaporate the water contained in this water-soluble adhesive. .

Since the adhesive layer 4 is arrange | positioned at one surface side of the said polarizer protective film 1, this adhesive layer 4 and a polarizer can be reliably adhere | attached by a water-soluble adhesive. Moreover, the said polarizer protective film 1 is controlled and formed in desired moisture permeability by the 1st control layer 3 and the 2nd control layer 5 arrange | positioned on both surfaces of the base material layer 2, For this reason, the said water-soluble At the time of adhesion by the adhesive, the water of the water-soluble adhesive can be evaporated accurately, and the above bonding process can be easily and reliably performed. In addition, since the main component of the polarizer protective film 1 is an acrylic resin, the dimensional change of the substrate layer 2 under high humidity is less than that of triacetyl cellulose, and a photoelastic effect is unlikely to occur. For this reason, the change of the retardation value of the said polarizer protective film 1 is small. In particular, since the 2nd control layer 5 is arrange | positioned at the other surface side of the base material layer 2, and the polarizer protective film 1 is controlled and formed by desired moisture permeability, the dimension change of the base material layer 2 is It is further suppressed and the dimensional change of the base material layer 2 can be made smaller, and the change of retardation value is small.

<Polarizing plate 11>

The polarizing plate 11 of FIG. 2 is equipped with the polarizer protective film 1 of FIG. 1 in one surface of the polarizer 12 which consists of polyvinyl alcohol, The cellulose ester conventionally used for the other surface of the polarizer 12 It has a structure provided with the polarizer protective film 13 which consists of. Between the polarizer 12 and the polarizer protective film 1, and between the polarizer 12 and the polarizer protective film 13, they are bonded by an adhesive agent (not shown).

The polarizer 12 is a uniaxially stretched polyvinyl alcohol resin film dyed with a dichroic substance (for example, iodine or dichroic dye). 500 or more are preferable and, as for the polymerization degree of the polyvinyl alcohol which comprises this polyvinyl alcohol resin film, 1000 or more are more preferable. 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 an organic solvent, the casting method, etc.). Although the thickness (average thickness) of the polarizer 12 differs according to the objective and the use of the liquid crystal display device in which the polarizing plate 11 is used, it is typically 5 micrometers or more and 100 micrometers or less. The polarizer 12 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 12, a series of manufacturing processes which consist of a swelling, dyeing, crosslinking, extending | stretching, water washing, and drying process of a polyvinyl alcohol resin film are employ | adopted. In each treatment 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 swelling, dyeing, crosslinking, stretching, washing with water, and the order of the treatments, the number of times, and the presence of drying can be appropriately set according to the purpose, the materials used and the conditions. For example, an extending | stretching process may be performed before dyeing process, and may be performed simultaneously with a 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 12 can be performed by immersing in a process bath which filled the polyvinyl alcohol resin film with water. Glycerine, potassium iodide, or the like may be appropriately added to the treatment bath. 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 treatment bath in the dyeing step is about 20 to 70 ° C., and the dipping time is about 1 to 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, glutaraldehyde, 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 processing 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 which performed various processes in the water washing bath. By this water washing process, unnecessary residue of a polyvinyl alcohol resin film can be washed away. The water washing bath may be pure 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. Typically, the immersion time is 1 second to 1 minute. The number of times of washing with water may be only once, and may be multiple times. As a drying process, natural drying, ventilation drying, heat drying can be employ | adopted, for example. Typically drying temperature is 20-80 degreeC, and drying time is 1-10 minutes. By performing each of the above steps, the polarizer 12 can be manufactured.

The polarizer protective film 13 melt | dissolves the flake raw material and plasticizer of a cellulose ester in methylene chloride, and makes it a viscous liquid, melt | dissolves a plasticizer in it, and dope it, and it casts on metal belts, such as stainless steel, which continuously rotates from a melt extruder And dried, stripped from the belt in a less dry state, dried and wound up. The cellulose ester is preferably selected from the group consisting of triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate, and triacetyl cellulose is particularly preferred.

Before the polarizer protective film 1 adheres to the polarizer 12, it is preferable to saponify the adhesive bonding layer 4 with an alkali. By this saponification, the ester group of a cellulose ester is converted into the hydroxyl group which is a hydrophilic group, and, thereby, chemical affinity with the polarizer protective film 1 and the polarizer 12 formed from polyvinyl alcohol which is a hydrophilic resin becomes high, and mutually The adhesiveness of is significantly improved.

As an 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 lower, the time required for the saponification treatment becomes long, which is not preferable. A saponification process is performed by immersing the polarizer protective film 1 in the above alkali aqueous solution bath over a suitable time.

The polarizer protective film 1 provided in the saponification process and the polarizer 12 which consists of polyvinyl alcohol are adhere | attached by the apparatus 21 shown typically in FIG. The apparatus 21 for bonding the plurality of films shown in FIG. 3 includes a nip 22 for supplying the polarizer 12, a nip 23 for supplying the polarizer protective film 1, and a means for supplying an adhesive ( 24 and the nip 25 for pressing and bonding the polarizer 12 and the polarizer protective film 1 through an adhesive agent are provided.

As an adhesive agent used for bonding together the easily bonding layer 4 of the polarizer protective film 1 and the polarizer 12 by the apparatus 21, polyvinyl alcohol-type adhesive agents, such as polyvinyl alcohol and polyvinyl butyral, for example. And vinyl latexes such as butyl acrylate. 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 preferably 0.1-15 mass%. 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 apparatus 21, the film-shaped polarizer 12 supplied from the nip 22 and the saponification-treated polarizer protective film 1 supplied from the nip 23 are sent out in the direction toward the nip 25. An appropriate amount of adhesive is supplied so as to be sandwiched between these films, followed by pressing with a nip 25, thereby adhering the adhesive layer 4 of the polarizer 12 and the polarizer protective film 1 to the polarizer 12. The structure by which the polarizer protective film 1 was laminated | stacked on one surface of is obtained. Next, the polarizing plate 11 is obtained by laminating | stacking the polarizer protective film 13 using the same means also to the surface of the polarizer 12 on which the polarizer protective film 1 is not laminated.

As for the said polarizing plate 11, the easily bonding layer 4 and the polarizer 12 of the polarizer protective film 1 are reliably adhere | attached by a water-soluble adhesive agent. Moreover, since the polarizer protective film 1 is controlled and formed by the 1st control layer 3 and the 2nd control layer 5 to a desired moisture permeability, the water of a water-soluble adhesive at the time of adhesion | attachment with the said water-soluble adhesive accurately evaporates. The bonding step can be easily and reliably performed. As a result, the said polarizing plate 11 can adhere | attach a polarizer protective film 1 and a polarizer reliably. Moreover, since the main component of the base material layer 2 of the said polarizer protective film 1 is acrylic resin, the dimension change of the base material layer 2 under high humidity is less than triacetyl cellulose, and a photoelastic effect hardly arises. For this reason, the change of the retardation value of the polarizer protective film 1 is small. In particular, since the 2nd control layer 5 is arrange | positioned at the other surface side of the base material layer 2, and the polarizer protective film 1 is controlled and formed by desired moisture permeability, the dimension change of the base material layer 2 is further made. By suppressing, the dimensional change of the base material layer 2 can be made smaller. Therefore, the polarizer protective film 1 of the said polarizing plate 11 can make small change of retardation value, and can exhibit desired optical characteristic.

<Liquid Crystal Display Element 31>

The liquid crystal display element 31 of FIG. 4 is viewed through the adhesive layer 35 with respect to both surfaces of the liquid crystal cell 32 in which the liquid crystal layer 34 is sandwiched by the transparent medium layer 33 (for example, glass). It is comprised by bonding the polarizing plate 11 of FIG. 2 which concerns on invention. The polarizer protective film 1 (substrate layer 2, the first control layer 3, the bonding layer 4, and the second control layer 5) according to the present invention has an outer surface side (liquid crystal) of the polarizer 12. On the inner surface side of the polarizer 12 (array mounting direction side of the liquid crystal cell 32), the polarizer protective film 13 which consists of the cellulose ester conventionally used arrange | positioned at the cell mounting direction opposite to the cell 32 is provided. Is placed. The material which comprises the liquid crystal layer 34, the transparent medium layer 33, and the adhesive bond layer 35 of the liquid crystal cell 32 is not specifically limited, A well-known thing can be used.

As for the said liquid crystal display element 31, the easily bonding layer 4 of the polarizer protective film 1 and the polarizer 12 are reliably adhere | attached with a water-soluble adhesive agent. Moreover, since the polarizer protective film 1 is controlled and formed by the 1st control layer 3 and the 2nd control layer 5 to a desired moisture permeability, the water of a water-soluble adhesive at the time of adhesion | attachment with the said water-soluble adhesive accurately evaporates. The adhesion step can be easily and accurately performed. As a result, the liquid crystal display element 31 can reliably adhere the polarizer protective film 1 and the polarizer 12. In addition, since the main component of the base material layer 2 of the polarizer protective film 1 is an acrylic resin, the dimensional change of the base material layer 2 under high humidity is less than that of triacetyl cellulose, and a photoelastic effect hardly occurs. For this reason, the change of the retardation value of the polarizer protective film 1 is small. In particular, since the 2nd control layer 5 is arrange | positioned at the other surface side of the base material layer 2, and the polarizer protective film 1 is controlled and formed by desired moisture permeability, the dimension change of the base material layer 2 is further made. By suppressing, the dimensional change of the base material layer 2 can be made smaller. Therefore, the said liquid crystal display element 31 can make small change of the retardation value of the polarizer protective film 1, and can exhibit desired optical characteristic. Therefore, the liquid crystal display element 31 can perform accurate display using the light of a light source effectively.

[Other Embodiments]

Moreover, the polarizer protective film, polarizing plate, and liquid crystal display element of this invention can be implemented in the aspect which implemented various changes and improvement other than the said aspect. For example, you may form so that a 2nd control layer of a polarizer protective film may become substantially thicker than a 1st control layer. As described above, the polarizer protective film can be substantially thicker than the first control layer, thereby imparting a curl prevention function against a force to be rounded to the inner side of the adhesive layer, and thus the polarizer protective film. It is possible to prevent the occurrence of overall curl. As a result, the polarizer protective film can improve dimensional stability.

The polarizer protective film may be arranged on both surfaces (inner surface side and outer surface side) of the polarizer. Thereby, the dimensional stability of the polarizer protective film arrange | positioned at the inner surface side and outer surface side of a polarizer can be improved. Moreover, the said polarizer protective film may be arrange | positioned at the inner surface side of a polarizer, and the other polarizer protective film may be arranged at the outer surface side of a polarizer.

On the other side of the second control layer (the side where the base layer is not laminated), another layer (antiglare layer, antireflection layer, antiglare layer, low refractive index layer or the like, antireflection layer, antistatic layer, hard coat layer ( Cured resin layer), an optical compensation layer, etc.) may be arranged. For example, by providing an anti-glare layer (anti-reflective layer) on the other surface side of a 2nd control layer, an anti-glare function can be exhibited in addition to the protection function to a polarizer. Moreover, the protection function with respect to a polarizer can be strengthened by providing a hard-coat layer in the other surface side of a 2nd control layer.

The said polarizing plate should just be laminated | stacked on any one surface side of a liquid crystal cell, and does not necessarily need to be laminated | stacked on both surfaces of a liquid crystal cell.

As mentioned above, the polarizer protective film of this invention, the polarizing plate using this polarizer protective film, and the liquid crystal display element using this polarizing plate make the dimensional change of the base material layer of the said polarizer protective film by humidity small, and the rita of the said polarizer protective film While suppressing the change of the value of the dilution, the polarizer protective film and the polarizer can be easily and reliably adhered with a water-soluble adhesive, and can be used for small products such as electronic calculators and watches, and for automobile meters, PC monitors, and televisions. It can be used in various fields ranging from large products.

One… Polarizer protective film
2… The substrate layer
3 ... First control layer
4… Adhesive layer
5 ... Second control layer
11 ... Polarizer
12... Polarizer
13 ... Polarizer protective film made of cellulose ester
21 ... Device for manufacturing polarizer
22... Nip
23 ... Nip
24 ... Glue supply means
25... Nip
31 ... Liquid crystal display device
32 ... Liquid crystal cell
33 ... Transparent media layer
34 ... Liquid crystal layer
35 ... Adhesive layer
41 ... Liquid crystal display device
42 ... Liquid crystal cell
43 ... Transparent media layer
44 ... Liquid crystal layer
45 ... Polarizer
46 ... Polarizer protective film
47 ... Polarizer
48 ... Adhesive layer

Claims (12)

As a polarizer protective film adhere | attached on the polarizer of a liquid crystal display panel,
A base layer containing acrylic resin as a main component,
1st control layer laminated | stacked on one surface side of this base material layer, and for controlling moisture permeability,
The adhesion easy layer laminated | stacked on one surface side of a 1st control layer,
2nd control layer laminated | stacked on the other surface side of a base material layer, and for controlling moisture permeability
And,
A 1st control layer and a 2nd control layer contain the same resin as a main component, The polarizer protective film characterized by the above-mentioned. The polarizer protective film of claim 1, wherein the first control layer is substantially the same thickness as the second control layer. The polarizer protective film of claim 1, wherein the second control layer is substantially thicker than the first control layer. The photoelastic coefficient of the said acrylic resin is -5 * 10 <^-12> / Pa or more and 5 * 10 <^-12> / Pa or less, The polarizer protective film of Claim 1 characterized by the above-mentioned. The polarizer protective film according to claim 1, wherein the easily bonding layer contains a cellulose ester-based resin as a main component. The number average molecular weight (Mn) of the said cellulose ester-type resin is 40000 or more and 100000 or less, The polarizer protective film of Claim 5 characterized by the above-mentioned. The polarizer protective film according to claim 1, wherein the first control layer and the second control layer contain an acrylic modified polyester resin as a main component. 8. The polarizer protective film according to claim 7, wherein the first control layer and the second control layer further contain a urethane resin. The polarizer protective film according to claim 1, wherein the water vapor transmission rate is 1 g / m ² · 24 h or more and 250 g / m ² · 24 h or less. The retardation value Re of the said base material layer is -15 nm or more and 15 nm or less, The polarizer protective film of Claim 1 characterized by the above-mentioned. The polarizer protective film of any one of Claims 1-10,
Polarizer adhere | attached by the water-soluble adhesive to the easily bonding layer of this polarizer protective film
It comprises a polarizing plate. With a liquid crystal cell,
The polarizing plate of Claim 11 laminated | stacked on one surface side of this liquid crystal cell
A liquid crystal display device comprising: a.

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