KR20120058418A - Process for producing a polarizing plate - Google Patents

Abstract

PURPOSE: A method for manufacturing a polarizing plate is provided to control an erosion of cycloolefin resin, thereby improving an adhesive force between a polarizing film and cycloolefin resin film while maintaining high performance of a polarizing plate. CONSTITUTION: A haze value of a protective film comprising a cycloolefin resin contact does not exceed 0.5% by contacting with a mixed organic solvent. The protective film is bonded to a polarizing film using an adhesive. The mixed organic solvent is a mixture giving no substantive changes caused by a contact with the organic solvent to the cycloolefin resin.

Description

Polarizing plate manufacturing method {PROCESS FOR PRODUCING A POLARIZING PLATE}

This invention relates to the method of manufacturing a polarizing plate by bonding the protective film containing cycloolefin resin to the surface of the polarizing film which consists of polyvinyl alcohol-type resins through an adhesive agent.

The polarizing plate is obtained by laminating a transparent resin film, for example, a cellulose acetate-based film represented by triacetyl cellulose, through an adhesive on one or both surfaces of a polarizing film made of a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. It is made up. This is bonded to a liquid crystal cell with an adhesive via other optical films, such as an optical compensation film and a retardation film, as needed, and becomes a component part of a liquid crystal display device.

BACKGROUND ART Liquid crystal display devices are rapidly expanding in applications as thin display screens such as liquid crystal televisions, liquid crystal monitors, and personal computers (PCs). In particular, the market expansion of liquid crystal TVs is remarkable, and the demand for low cost is also very strong. Conventionally, in the polarizing plate for liquid crystal TV, what laminated | stacked the triacetyl cellulose film with the water-based adhesive on both surfaces of the polarizing film which consists of polyvinyl alcohol-type resins has become mainstream, and the retardation film was laminated | stacked on one surface of this polarizing plate through the adhesive. As the retardation film laminated to the polarizing plate, a stretched processed product of a polycarbonate resin film or a stretched processed product of a cycloolefin resin film is used, but for a liquid crystal TV, a phase difference made of a cycloolefin resin film with a very small phase difference unevenness at a high temperature is used. Films are used a lot. Improvements are being made to reduce the number of parts to be constructed or to simplify the manufacturing process for the improved product and the reduction of product cost for the bonded article formed of a polarizing plate and a stretched cycloolefin resin film. For example, JP H 08-43812-A discloses a laminated structure of a cycloolefin-based (norbornene-based) resin film / polarizing film / triacetylcellulose film having a phase difference function.

Further, JP 2005-70140-A, JP 2005-181817-A, and JP 2005-208456-A describe bonding a polyvinyl alcohol polarizing film and a cycloolefin resin film with a urethane-based water-based adhesive. On the other hand, JP 2004-245925-A describes the use of an active energy ray-curable adhesive containing an epoxy compound when bonding a low moisture-permeable protective film including a cycloolefin resin film to a polyvinyl alcohol polarizing film.

Furthermore, KR 2010-92265-A includes cyclohexanone, methyl isobutyl ketone, diethyl ether, ethylene oxide, tetrahydrofuran, tetrahydropyrane, n-heptane, n-hexane, cresol, toluene, xylene, phthalate dioxane A method of surface treatment by applying at least one solution selected from the group consisting of methyl and dimethylformamide, typically, an aqueous solution of a compound selected from these groups, to a cycloolefin resin film is disclosed. Moreover, the method of manufacturing the polarizing plate by bonding the cycloolefin resin film surface-treated in this way to a polyvinyl alcohol-type polarizing film via an adhesive agent is also disclosed.

When an aqueous adhesive is used for joining a polyvinyl alcohol polarizing film and a cycloolefin resin film, the adhesive force of both is not necessarily sufficient, For example, it could peel at the interface of a polarizing film and a cycloolefin resin film. . Therefore, when the polarizing plate is disposed on the liquid crystal cell and then the work (called rework) to be reattached due to the defect of the polarizing plate or the like is required, the inside of the laminated structure of the polarizing plate as compared to the adhesive force of the pressure-sensitive adhesive bonding the polarizing plate and the liquid crystal cell. Adhesive force (eg, adhesion between polarizing film and cycloolefin resin film) is relatively small and only cycloolefin resin remains on the glass cell from which the polarizing plate is removed so that the liquid crystal cell cannot be reused. There was.

According to the method disclosed in KR 2010-92265-A, although the adhesion of the cycloolefin resin film to the polyvinyl alcohol polarizing film can be increased, the surface treatment with an aqueous solution is enough to evaporate thereafter. A drying furnace maintained at a temperature of is required. On the other hand, it is also conceivable to apply a liquid (organic solvent) directly to the cycloolefin-based resin film at room temperature among the organic compounds specifically disclosed in the above literature, in which case the cycloolefin-based resin film can be excessively eroded. there was.

The objective of this invention is to improve the adhesive force of a polarizing film and a cycloolefin resin film in the polarizing plate by which the protective film containing cycloolefin resin is bonded to the polarizing film which consists of polyvinyl alcohol-type resin through an adhesive agent. Is in. Another object of the present invention is a polarizing film and a cycloolefin while maintaining a high performance as a polarizing plate by bonding to a polyvinyl alcohol polarizing film through an adhesive in a state in which the cycloolefin resin film is processed without excessively eroding. It is to raise adhesive force with a system resin film.

As a result, a mixture of an organic solvent that changes the cycloolefin resin when it is in contact with the cycloolefin resin film and an organic solvent that does not substantially change the cycloolefin resin when it is in contact with the cycloolefin resin film It has been found that it is effective to contact the cycloolefin resin film so that the haze value of the cycloolefin resin film does not exceed 0.5% using. In addition, if the alicyclic hydrocarbon is an organic solvent which changes the cycloolefin resin by contact, it is effective for the contact treatment to the cycloolefin resin film alone, and the cycloolefin resin is brought into contact with the alicyclic hydrocarbon. It has also been found that combinations of organic solvents that do not change are much more effective.

That is, this invention includes the following.

[1] A method of manufacturing a polarizing plate by bonding a protective film containing a cycloolefin resin to a polarizing film having a dichroic dye adsorbed on a polyvinyl alcohol resin, using an adhesive, wherein the cycloolefin resin is included. A mixed organic solvent that is substantially free of a solute in a mixture of an organic solvent that does not substantially change the cycloolefin resin by contacting the protective film with the organic solvent that changes the cycloolefin resin by contact. A method of manufacturing a polarizing plate comprising contacting the polarizing film through the adhesive after contacting so that the haze value of the protective film does not exceed 0.5%.

[2] a second protective film comprising a thermoplastic resin on the other side of the polarizing film and a first protective film containing a cycloolefin resin on one side of the polarizing film on which the dichroic dye is adsorbed and oriented to the polyvinyl alcohol resin. A method of manufacturing a polarizing plate by bonding films to each other using an adhesive, wherein the cycloolefin is contacted by contacting a first protective film containing the cycloolefin resin with an organic solvent that changes the cycloolefin resin by contact. The polarizing film through the adhesive after contacting the mixed organic solvent substantially free of solutes with a mixture of an organic solvent that does not substantially change the system resin so that the haze value of the first protective film does not exceed 0.5%. The polarizing plate manufacturing method containing bonding to a.

[3] A method of manufacturing a polarizing plate by bonding a protective film containing a cycloolefin resin to a polarizing film having a dichroic dye adsorbed on a polyvinyl alcohol resin, using an adhesive, wherein the cycloolefin resin is included. Manufacturing a polarizing plate comprising contacting a protective film with an organic solvent containing an alicyclic hydrocarbon and substantially free of solutes so that the haze value of the protective film does not exceed 0.5% and then bonding the polarizing film through the adhesive. Way.

[4] A second protective film comprising a thermoplastic resin on a second side of the polarizing film and a first protective film containing a cycloolefin resin on one side of the polarizing film on which the dichroic dye is adsorbed and oriented to the polyvinyl alcohol resin. A method of manufacturing a polarizing plate by bonding films to each other using an adhesive, wherein the first protective film containing the cycloolefin-based resin comprises an organic solvent containing an alicyclic hydrocarbon and substantially free of solutes, and the first protective film. A method of manufacturing a polarizing plate comprising bonding to the polarizing film through the adhesive after contacting so that the haze value does not exceed 0.5%.

[5] The production method described in [3] or [4], wherein the alicyclic hydrocarbon is a compound represented by the following Formula (I):

(I)

(I)

(In the above formula, m is an integer of 2 to 6, R is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)

[6] The production method according to any one of [3] to [5], wherein the organic solvent is a mixed solvent which further contains, in addition to the alicyclic hydrocarbon, an organic solvent which does not substantially change the cycloolefin resin by contact. .

[7] The production method according to [6], wherein the organic solvent which does not substantially change the cycloolefin resin is an alkyl ester of an organic acid.

[8] The production method according to [7], wherein the alkyl ester of the organic acid is an acetic acid ester.

[9] The production method according to [8], wherein the acetate ester is ethyl acetate, isopropyl acetate or propyl acetate.

[10] The protective film containing the cycloolefin-based resin has an in-plane retardation value of 30 nm or more before contact with the organic solvent, and the in-plane retardation value of the protective film after the contact exceeds 3 nm from the in-plane retardation value before the contact. The manufacturing method in any one of [1]-[9] which makes contact so that it may not fall below.

[11] The production method according to any one of [1] to [10], which simultaneously performs an operation of drying the organic solvent when the protective film containing the cycloolefin resin is brought into contact with the organic solvent.

[12] The production method according to any one of [1] to [11], wherein the adhesive is an aqueous adhesive.

[13] The production method according to [12], in which the adhesive contains a polyvinyl alcohol-based resin.

According to this invention, in the polarizing plate in which the protective film containing cycloolefin resin is bonded to the polarizing film which consists of polyvinyl alcohol-type resin through an adhesive agent, the adhesive force of a polarizing film and a cycloolefin resin film can be improved. . In particular, erosion of the cycloolefin-based resin film is suppressed and a polarizing plate having improved adhesion between the polarizing film and the cycloolefin-based resin film can be manufactured while maintaining high performance as a polarizing plate.

In this invention, the protective film containing cycloolefin resin is bonded to a polarizing film in which a dichroic dye is adsorbed-oriented to polyvinyl alcohol-type resin through an adhesive agent, and it is set as a polarizing plate. A cycloolefin resin film may be bonded to both surfaces of a polarizing film, and may be bonded to one surface. When a cycloolefin resin film is bonded to one surface of a polarizing film, it is preferable to bond together the protective film which consists of another thermoplastic resin on the opposite surface through an adhesive agent. Hereinafter, the protective film containing a cycloolefin resin can be called a "first protective film", and the protective film which consists of another thermoplastic resin can be called a "second protective film", respectively. First, each structural member of the polarizing plate manufactured by this invention is demonstrated.

[Polarizing Film]

In the polarizing film used for this invention, a dichroic dye is specifically, adsorbed-oriented to a polyvinyl alcohol-type resin film. The dichroic dye can be oriented in the stretching direction by uniaxially stretching the polyvinyl alcohol-based resin film before, during or after the adsorption of the dichroic dye. Polyvinyl alcohol-type resin is obtained by saponifying polyvinyl acetate type resin. As polyvinyl acetate type resin, besides polyvinyl acetate which is a homopolymer of vinyl acetate, the copolymer of vinyl acetate and the other monomer copolymerizable here, for example, ethylene-vinyl acetate copolymer, etc. are mentioned. As another monomer copolymerizable with vinyl acetate, unsaturated carboxylic acids, unsaturated sulfonic acids, olefins including the said ethylene, vinyl ether, acrylamide which has an ammonium group, etc. are mentioned, for example.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified. For example, polyvinyl formal, polyvinyl acetal, polyvinylbutylal, and the like modified with aldehydes may also be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is usually in the range of 1,000 to 10,000, preferably in the range of 1,500 to 5,000.

What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a conventionally known suitable method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 10-150 micrometers.

The polarizing film is usually a step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye (dyeing step), and a step of treating the polyvinyl alcohol-based resin film to which the dichroic dye is adsorbed with an aqueous solution of boric acid. It is manufactured through the process (water washing process) to wash after (boric acid treatment process) and this process with this boric acid aqueous solution.

In addition, the polyvinyl alcohol-based resin film is uniaxially stretched at the time of manufacturing the polarizing film, the uniaxial stretching may be performed before the dyeing treatment step, may be performed during the dyeing treatment step, may be carried out after the dyeing treatment step. When uniaxial stretching is performed after the dyeing treatment step, this uniaxial stretching may be performed before the boric acid treatment step or may be performed during the boric acid treatment step. Of course, it is also possible to perform uniaxial stretching in these plural steps. Uniaxial stretching may be performed by passing between spaced rolls with different circumferential speeds, or may be carried out by sandwiching a thermal roll. Moreover, it may be dry drawing which extends | stretches in air | atmosphere, or it may be wet drawing which extends | stretches in the state swollen with a solvent. The draw ratio is usually about 3 to 8 times.

Dyeing with a dichroic dye of a polyvinyl alcohol-type resin film is performed by immersing a polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye, for example. As a dichroic dye, iodine, a dichroic organic dye, etc. are specifically used. Dichroic organic dyes include dichroic direct dyes made of disazo compounds such as C.I.DIRECT RED 39, dichroic direct dyes made of compounds such as tris azo and tetrakis azo. In addition, it is preferable that the polyvinyl alcohol-based resin film be immersed in water before the dyeing treatment.

When iodine is used as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is employ | adopted normally. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. When iodine is used as a dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 ° C, and the immersion time (dyeing time) in the aqueous solution is usually 20 to 1,800 seconds.

On the other hand, when using a dichroic organic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic organic dye is employ | adopted normally. The content of the dichroic organic dye in this aqueous solution is usually 1 × 10 ⁻⁴ to 10 parts by weight, preferably 1 × 10 ⁻³ to 1 part by weight, more preferably 1 × 10 ⁻³ per 100 parts by weight of water. To 1 × 10 ⁻² parts by weight. This aqueous solution may contain inorganic salts, such as sodium sulfate, as a dyeing adjuvant. When using a dichroic organic dye as a dichroic dye, the temperature of the dye aqueous solution used for dyeing is 20-80 degreeC normally, and the immersion time (dyeing time) in this aqueous solution is 10 to 1,800 second normally.

A boric acid treatment process is performed by immersing the polyvinyl alcohol-type resin film dyed by the dichroic dye in boric-acid aqueous solution. The content of boric acid in the boric acid aqueous solution is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. In the case where iodine is used as the dichroic dye in the aforementioned dyeing step, the boric acid aqueous solution used in this step preferably contains potassium iodide. In this case, the content of potassium iodide in boric acid aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. Immersion time in boric acid aqueous solution is 60 to 1,200 second normally, Preferably it is 150 to 600 second, More preferably, it is 200 to 400 second. The temperature of boric-acid aqueous solution is 50 degreeC or more normally, Preferably it is 50-85 degreeC, More preferably, it is 60-80 degreeC.

In the following water washing process, the water washing process is performed by immersing the polyvinyl alcohol-type resin film after boric acid treatment mentioned above in water, for example. The temperature of water in a water washing process is 5-40 degreeC normally, and immersion time is 1-120 second normally. After the water washing treatment, a drying treatment is usually performed to obtain a polarizing film. Drying process can be performed using a hot air dryer, a far-infrared heater, etc., for example. The temperature of a drying process is 30-100 degreeC normally, Preferably it is 50-80 degreeC. The drying treatment time is usually 60 to 600 seconds, preferably 120 to 600 seconds.

The polarizing film by which the dichroic dye is adsorption-oriented to the uniaxially-stretched polyvinyl alcohol-type resin film as mentioned above can be produced. The thickness of this polarizing film can be about 5-40 micrometers.

[Cycloolefin resin film]

In this invention, the 1st protective film provided in at least one side of a polarizing film is comprised by a cycloolefin resin film, and this cycloolefin resin film is bonded to a polarizing film via an adhesive agent.

Cycloolefin resin is thermoplastic resin which has a unit of the monomer which consists of cyclic olefins (cycloolefin), such as a norbornene and a polycyclic norbornene monomer, and is also called thermoplastic cycloolefin resin. The cycloolefin-based resin may be a hydrogenated product of the ring-opening polymer of the cycloolefin or the ring-opening copolymer using two or more cycloolefins, or an aromatic compound having a polymerizable double bond such as a cycloolefin and a chain olefin or vinyl group. May be an addition polymer of. A polar group may be introduce | transduced into cycloolefin resin.

When a 1st protective film is comprised using the copolymer of a cycloolefin and the aromatic compound which has a chain | strand-shaped olefin and / or a vinyl group, ethylene, a propylene, etc. are mentioned as chain | strand olefin, Furthermore, aromatic having a vinyl group Examples of the compound include styrene, α-methyl styrene, nuclear alkyl substituted styrene, and the like. In such a copolymer, although the unit of the monomer which consists of cycloolefin may be 50 mol% or less, Preferably it is about 15-50 mol%. In particular, in the case of constituting the first protective film using a ternary copolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group, the unit of the monomer consisting of the cycloolefin can be made in a relatively small amount as described above. . In such a terpolymer, the unit of the monomer which consists of a chain type olefin is 5 to 80 mol% normally, and the unit of the monomer which consists of an aromatic compound which has a vinyl group is 5 to 80 mol% normally.

Cycloolefin-based resin films can be used commercially available products, such as "TOPAS" produced by TOPAS ADVANCED POLYMERS GnbH in Germany and sold by Polyplastics in Japan, "Aton" sold by JSR Corporation, "ZEONOR" and "ZEONEX" sold by Nihon Xeon, "Apel" sold by Mitsui Chemicals Co., Ltd. (all are brand names), etc. are mentioned here. In order to form such a cycloolefin resin into a film, well-known methods, such as a solvent casting method and a melt-extrusion method, are used suitably. In addition, "Essena" and "SCA40" sold by Sekisui Chemical Co., Ltd., "Zeonor film" sold by Nihon Xeon, "Aton film" sold by JSR Corporation, for example. The commercial item of the cycloolefin resin film forming film formed previously, such as (all are brand names), can also be used for a 1st protective film.

The cycloolefin resin film used for the first protective film may be uniaxially stretched or biaxially stretched. The draw ratio in this case is usually 1.1 to 5 times, preferably 1.1 to 3 times. By this extending | stretching, retardation can be provided and it can be set as retardation film. Although the in-plane phase difference value may be suitably set according to the kind of liquid crystal cell applied, it is preferable to set it as 30 nm or more generally. The upper limit of the in-plane retardation value is not particularly limited, but is preferably up to about 300 nm.

Although it is preferable that the cycloolefin resin film used for a 1st protective film is thin, when it is too thin, there exists a tendency for intensity | strength to fall and workability falls, and when too thick, there exists a tendency for transparency to fall or the weight of a polarizing plate becomes large. From such a viewpoint, the thickness of the protective film containing cycloolefin resin is 5 to 200 micrometers normally, Preferably it is 10 to 150 micrometers, More preferably, it is 20-100 micrometers.

The protective film containing a cycloolefin resin is adhere | attached to a polarizing film using the adhesive agent as demonstrated in detail below. In the adhesion of both, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment, etc. is appropriately applied to the adhesive surface of the polarizing film and / or the protective film bonded thereto in order to improve the adhesiveness. You can also carry out. Hereinafter, the adhesive agent used for adhesion | attachment of a polarizing film and a cycloolefin resin film is demonstrated.

[glue]

An adhesive agent is used for adhesion | attachment of a polarizing film and a cycloolefin resin film. The adhesive agent used for this purpose should just express adhesive force with respect to both, For example, the curable adhesive agent containing the water-based adhesive agent or the active energy ray curable compound which melt | dissolved or disperse | distributed the adhesive component in water is mentioned. Considering that the surface of the polarizing film is hydrophilic, an aqueous adhesive in which the adhesive component is dissolved or dispersed in water is preferable. An aqueous adhesive is also preferable from a viewpoint which can thin the adhesive bond layer after hardening. Examples of the adhesive component that is the main component of the water-based adhesive agent include polyvinyl alcohol resins and urethane resins.

When polyvinyl alcohol-type resin is used as a main component of an aqueous adhesive agent, this polyvinyl alcohol-type resin is obtained by saponifying polyvinyl acetate type resin. As polyvinyl acetate type resin, the copolymer etc. of vinyl acetate and the other monomer copolymerizable with it besides the polyvinyl acetate which is a homopolymer of vinyl acetate are illustrated. As another monomer copolymerized with vinyl acetate, unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamide which has an ammonium group, etc. are mentioned, for example. It is preferable that the polyvinyl alcohol-type resin used for an adhesive agent has a suitable degree of polymerization, for example, when it is set as the aqueous solution of 4 weight% concentration, the viscosity will be in the range of 4-50 mPa-sec, Furthermore, the range of 6-30 mPa-sec. It is more preferable to stay inside.

Although the saponification degree of the polyvinyl alcohol-type resin used for an adhesive agent is not specifically limited, Generally, it is preferable that it is 80 mol% or more, Furthermore, it is more preferable that it is 90 mol% or more. When the saponification degree of polyvinyl alcohol-type resin used for an adhesive agent is low, there exists a tendency for the water resistance of the adhesive bond layer obtained to be inadequate easily.

As the adhesive, a modified polyvinyl alcohol-based resin is preferably used. Preferred modified polyvinyl alcohol-based resins include acetacetyl-modified polyvinyl alcohol-based resins, anion-modified polyvinyl alcohol-based resins, and cation-modified polyvinyl alcohol-based resins. By using such modified polyvinyl alcohol-based resin, the effect of improving the water resistance of the adhesive layer can be easily obtained.

The acetacetyl group-modified polyvinyl alcohol-based resin has an acetacetyl group (CH ₃ COCH ₂ CO-) in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton, and may have other groups such as an acetyl group. This acetacetyl group exists in the state which the hydrogen atom of the hydroxyl group which comprises polyvinyl alcohol is substituted typically. The acetacetyl group-modified polyvinyl alcohol-based resin can be produced, for example, by a method of reacting polyvinyl alcohol with diketene. Acetacetyl group-modified polyvinyl alcohol-based resin is preferred for improving the durability of the adhesive layer because it has an acetacetyl group which is a highly reactive functional group.

There is no restriction | limiting in particular if content of acetacetyl group in acetacetyl group modified polyvinyl alcohol-type resin is 0.1 mol% or more. Content of acetacetyl group here is the value which expressed the mole fraction of the acetacetyl group with respect to the total amount of a hydroxyl group, an acetacetyl group, and other ester groups (acetyl group etc. in polyvinyl alcohol-type resin in%, "acetyl." Acetylation degree ". When the acetacetylation degree in the polyvinyl alcohol-based resin is less than 0.1 mol%, the effect of improving the water resistance of the adhesive layer is not necessarily sufficient. Acetic in the polyvinyl alcohol-based resin The degree of acetylation is about 0.1 to 40 mol%, more preferably 1 to 20 mol%, particularly preferably 2 to 7 mol% When the acetacetylation degree exceeds 40 mol%, the effect of improving water resistance becomes small.

The anion-modified polyvinyl alcohol-based resin contains an anionic group, typically a carboxyl group (-COOH) or a salt thereof, in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton, and may have other groups such as acetyl group. It may be. The anion-modified polyvinyl alcohol-based resin can be produced by, for example, copolymerizing an unsaturated monomer having an anionic group (typically a carboxyl group) with vinyl acetate and then saponifying. On the other hand, the cation-modified polyvinyl alcohol-based resin contains a cationic group, typically a tertiary amino group or a quaternary ammonium group, in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton, and has other groups such as acetyl group. There may be. The cation-modified polyvinyl alcohol-based resin can be produced by, for example, copolymerizing an unsaturated monomer having a cationic group (typically a tertiary amino group or a quaternary ammonium group) with vinyl acetate and then saponifying.

The adhesive used in the present invention may, of course, contain two or more of the above-described modified polyvinyl alcohol-based resins, and may also be unmodified polyvinyl alcohol-based resins (specifically, complete or partial saponified polyvinyl acetate). And it may include all of the above-mentioned modified polyvinyl alcohol-based resin.

The polyvinyl alcohol-based resin constituting the adhesive can be appropriately selected from commercially available products. Specifically, for example, "PVA-117H" sold by Kuraray Co., Ltd. and "Gosenol NH-20" sold by Nihon Synthetic Chemical Industry Co., Ltd. as polyvinyl alcohol having high saponification degree. , Acetacetyl group-modified polyvinyl alcohol, "GOHSEFIMER Z" series sold by Nihon Synthetic Chemical Industry Co., Ltd., anion-modified polyvinyl alcohol sold by Kuraray Co., Ltd. "KL-318" and "KM-118" or "Gosenal T-330" sold by Nihon Synthetic Chemical Industry Co., Ltd., "CM" modified polyvinyl alcohol, "CM sold by Kuraray Co., Ltd." "Kosepimer K-210" sold by Nippon Synthetic Chemical Industry Co., Ltd., etc. are mentioned.

Although the concentration of the polyvinyl alcohol-based resin in the adhesive is not particularly limited, it is preferably used so that the polyvinyl alcohol-based resin is in the range of 1 to 20 parts by weight with respect to 100 parts by weight of water. It is more preferable to be in the range of 1 to 15 parts by weight, more preferably 1 to 10 parts by weight, particularly preferably 2 to 10 parts by weight. When the concentration of the polyvinyl alcohol-based resin in the aqueous solution is too small, the adhesiveness tends to be lowered. On the other hand, when the concentration is too large, the optical characteristics of the polarizing plate obtained tend to be lowered. The water used for the adhesive may be pure water, ultrapure water, tap water, or the like, and is not particularly limited. Pure water or ultrapure water is preferred from the viewpoint of maintaining uniformity and transparency of the adhesive layer to be formed. Moreover, alcohol, such as methanol and ethanol, can also be added to aqueous adhesive solution.

A crosslinking agent can be contained in the aqueous adhesive which has polyvinyl alcohol-type resin as a main component. The crosslinking agent should just be a compound which has a functional group reactive with polyvinyl alcohol-type resin, and what is conventionally used with the polyvinyl alcohol-type adhesive agent can be used without a restriction | limiting. When the compound which can become a crosslinking agent is posted according to functional groups, Isocyanate compound which has at least 2 isocyanate group (-NCO) in a molecule | numerator; An epoxy compound having at least two epoxy groups (crosslinked -O-) in the molecule; Mono- or di-aldehydes; Organic titanium compounds; Inorganic salts of divalent or trivalent metals such as magnesium, calcium, iron, nickel, zinc and aluminum; Metal salts of glyoxylic acid; Methylolmelamine and the like.

Specific examples of the isocyanate compound serving as a crosslinking agent include tolylene diisocyanate, hydrogenated tolylene diisocyanate, adduct of trimethylolpropane and tolylene diisocyanate, diphenylmethane diocyanate, triphenylmethane tri Isocyanate, isophorone diisocyanate, these ketooxime block water, a phenol block water, etc. are mentioned.

Specific examples of the epoxy compound to be a crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, di- or tri-glycidyl ether of glycerine, 1,6-hexanediol Epichlorohydrin is reacted with polyamide polyamine, which is a reactant of diglycidyl ether, trimethylolpropanetriglycidyl ether, diglycidyl aniline, diglycidylamine, polyalkylenepolyamine and dicarboxylic acid The water-soluble polyamide epoxy resin etc. which are obtained by making it make it are mentioned.

Specific examples of the monoaldehydes used as crosslinking agents include formaldehyde, acetaldehyde, propionaldehyde, butylaldehyde, and the like. Aldehyde, male aldehyde, phthal dialdehyde, etc. are mentioned.

As for the organic titanium compound used as a crosslinking agent, various products are sold by Matsumoto refinery chemicals. Water-soluble organics suitably used in the present invention from the home page according to the company's organic titanium compound (Internet <URL: wvw.m-chem.co.jp/products/products1.html>, retrieved Nov. 18, 2010) If a titanium compound is posted in the order of its trial formula, the chemical name of the company, and the brand name of the company, there are the followings.

[(CH ₃ ) ₂ CHO] ₂ Ti [OCH ₂ CH ₂ N (CH ₂ CH ₂ OH) ₂ ] ₂ : The chemical name "Titandiisopropoxybis (triethanol aluminate)""OrganicsTC-400", (HO) ₂ Ti [OCH (CH ₃ ) COO-] ₂ (NH ₄ ⁺ ) ₂ : Chemical name of the company "Titanlactate ammonium salt, trade name of this company" Orgatics TC -300 ", (HO) ₂ Ti [OCH (CH ₃ ) COOH] ₂ : the chemical name" Titanlactate ", the company's trade names" Orgatics TC-310 "and" Orgatics " TC-315 ".

In addition, the metal salt of glyoxylic acid is preferably an alkali metal salt or an alkaline earth metal salt, and examples thereof include sodium glyoxylate, potassium glyoxylate, magnesium glyoxylate and calcium glyoxylate. .

Among these crosslinking agents, epoxy compounds including the above-mentioned water-soluble polyamide epoxy resins, aldehydes, methylolmelamine, alkali metal or alkaline earth metal salts of glyoxylic acid, and the like are suitably used.

The crosslinking agent is preferably dissolved in water together with the polyvinyl alcohol-based resin to form an adhesive. However, as stated below, since the amount of the crosslinking agent in the aqueous solution may be slightly, it can be used as the crosslinking agent as long as it has a solubility of at least about 0.1% by weight with respect to water, for example. Of course, a compound having a solubility in water of a degree generally called water soluble is suitable as a crosslinking agent for use in the present invention.

Although the compounding quantity of a crosslinking agent is designed suitably according to the kind etc. of polyvinyl alcohol-type resin, it is about 5 to 60 weight part normally with respect to 100 weight part of polyvinyl alcohol-type resin, Preferably it is 10-50 weight part. If a crosslinking agent is mix | blended in this range, favorable adhesiveness can be obtained. As described above, in order to improve the durability of the adhesive layer, acetacetyl-modified polyvinyl alcohol-based resin is preferably used. In this case, 5 to 60 parts by weight of a crosslinking agent based on 100 parts by weight of polyvinyl alcohol-based resin, Furthermore, it is preferable to mix | blend in the ratio of 10-50 weight part. If the amount of the crosslinking agent is too large, the reaction of the crosslinking agent proceeds in a short time, and the adhesive tends to gel prematurely. As a result, the pot life becomes extremely short, which makes industrial use difficult.

In the adhesive, a conventionally known suitable additive such as a silane coupling agent, a plasticizer, an antistatic agent, and fine particles may be blended within the range not impairing the effects of the present invention.

When using urethane resin as a main component of an aqueous adhesive agent, the mixture of the polyester-type ionomer type urethane resin and the compound which has glycidyloxy group is mentioned as an example of a suitable adhesive agent. The polyester ionomer-type urethane resin here is a urethane resin which has a polyester frame | skeleton, and a small amount of ionic component (hydrophilic component) is introduce | transduced in it. Such ionomer-type urethane resins are suitably used for water-based adhesives because they are emulsified directly in water without using an emulsifier. The use of polyester-based ionomer-type urethane resins for adhesives of polarizing films and protective films is known and described, for example, in JP 2005-070140-A, JP 2005-181817-A, and JP 2005-208456-A.

Curable adhesive containing an active energy ray curable compound can also be used for bonding a polarizing film and a cycloolefin resin film together. An "active energy ray curable compound" means the compound which can be hardened by irradiation of an active energy ray. The active energy ray curable compound may be cationic polymerizable or may be radical polymerizable. As an example of a cationic polymerizable compound, the epoxy compound which has at least 1 epoxy group in a molecule | numerator, the oxetane compound which has at least 1 oxetane ring in a molecule | numerator, etc. are mentioned. Moreover, as an example of a radically polymerizable compound, the (meth) acrylic-type compound etc. which have at least 1 (meth) acryloyloxy group in a molecule | numerator are mentioned. In addition, a "(meth) acryloyloxy group" means a methacryloxy group or acryloyloxy group.

Thus, it is preferable that the active energy ray curable compound used for sticking each other contains an epoxy compound at least, and, thereby, the adhesiveness between a polarizing film and a cycloolefin resin film is exhibited better.

It is preferable that an epoxy compound has an epoxy compound which does not contain an aromatic ring in a molecule | numerator as a main component from a viewpoint of weather resistance, a refractive index, cationic polymerizability, etc. As an epoxy compound which does not contain an aromatic ring in a molecule | numerator, the glycidyl ether of an polyol which has an alicyclic ring, an aliphatic epoxy compound, an alicyclic epoxy compound, etc. can be illustrated. Epoxy compounds suitably used for such curable adhesives are described in detail, for example, in JP 2004-245925-A, but the outline will be described here.

Glycidyl ether of the polyol having an alicyclic ring may be a glycidyl ether of the nuclear hydrogenated polyhydroxy compound obtained by selectively hydrogenating the aromatic polyol to the aromatic ring under pressure in the presence of a catalyst. Aromatic polyols include, for example, bisphenol type compounds such as bisphenol A, bisphenol F and bisphenol S; Novolak-type resins such as phenol novolak resin, cresol novolak resin and hydroxybenzaldehyde phenol novolak resin; And polyfunctional compounds such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone and polyvinylphenol. It can be set as glycidyl ether by making epichlorohydrin react with the alicyclic polyol obtained by performing a hydrogenation reaction to the aromatic ring of these aromatic polyols. Especially among the glycidyl ethers of the polyol which has such an alicyclic ring, the diglycidyl ether of hydrogenated bisphenol A is mentioned.

The aliphatic epoxy compound may be a polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. More specifically, diglycidyl ether of 1,4-butanediol; Diglycidyl ether of 1,6-hexanediol; Triglycidyl ether of glycerine; Triglycidyl ether of trimethylolpropane; Diglycidyl ether of polyethylene glycol; Diglycidyl ether of propylene glycol; Polyglycidyl ethers of polyether polyols obtained by adding one or two or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol or glycerine; Can be mentioned.

An alicyclic epoxy compound is a compound which has at least 1 epoxy group in a molecule | numerator bonded to an alicyclic ring. Here, "epoxy group couple | bonded with an alicyclic ring" means the oxygen atom -O- of bridge | crosslinking in the structure represented by following formula (II), and n is an integer of 2-5 in a following formula.

The compound in which the group of the form in which one or a plurality of hydrogen atoms in (CH ₂ ) _n in this formula (II) has been removed is bonded to another chemical structure can be an alicyclic epoxy compound. In addition, one or a plurality of hydrogen atoms in (CH ₂ ) _n forming an alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.

Among the epoxy compounds described above, an alicyclic epoxy compound, that is, a compound in which at least one of the epoxy groups is bonded to an alicyclic ring is preferable, and in particular, an oxabicyclohexane ring [where n = 3 in the formula (II)] or The epoxy compound which has an oxa bicyclo heptane ring [what is n = 4 in said Formula (II)] is used more preferably, since the elasticity modulus of hardened | cured material is high and it provides favorable adhesiveness between a polarizing film and a protective film. The specific example of an alicyclic epoxy compound is shown below. Here, first, the compound name is taken, and then, corresponding chemical formulas are shown, and the compound names and the corresponding chemical formulas are denoted by the same symbols.

A: 3, 4- epoxycyclohexylmethyl 3, 4- epoxycyclohexane carboxylate

B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,

C: ethylene bis (3,4-epoxycyclohexanecarboxylate),

D: bis (3,4-epoxycyclohexylmethyl) adipate,

E: bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,

F: diethylene glycol bis (3,4-epoxycyclohexylmethyl ether),

G: ethylene glycol bis (3,4-epoxycyclohexylmethyl ether)

H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispyro [5.2.2.5.2.2] Henicosan,

I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy-1,5-dioxaspiro [5.5] undecane,

J: 4-vinylcyclohexene dioxide,

K: limonene dioxide,

L: bis (2,3-epoxycyclopentyl) ether,

M: dicyclopentagene dioxide and the like.

In a curable adhesive agent, an epoxy compound may be used individually by 1 type, and may use 2 or more types together.

Moreover, curable adhesive agent may contain an oxetane compound other than the said epoxy compound. By adding an oxetane compound, the viscosity of a curable adhesive agent can be reduced and a cure rate can be speeded up.

An oxetane compound is a compound having at least one oxetane ring (four-membered ring ether) in a molecule, for example, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxeta Nil) methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyl Oxymethyl) oxetane, a phenol novolak oxetane, etc. are mentioned. These oxetane compounds can obtain a commercial item easily, For example, all are brand names sold by Toa Synthetic Co., Ltd., "Alonoxetane OXT-101", "Alonoxetane OXT-121", "Alonox" Cetane OXT-2U "," Alonoxetane OXT-221 "," Alonoxetane OXT-212 ", etc. are mentioned. Although the compounding quantity of an oxetane compound is not specifically limited, Usually, it is 50 weight% or less based on the whole active energy ray curable compound, Preferably it is 10-40 weight%.

When the curable adhesive contains a cation polymerizable compound such as an epoxy compound or an oxetane compound, the curable adhesive usually contains a photocationic polymerization initiator. When the photocationic polymerization initiator is used, it is possible to form the adhesive layer at room temperature, so that the distortion due to heat resistance and expansion of the polarizing film is reduced, and the polarizing film and the protective film can be adhered to each other in an adhesive manner. Moreover, since a photocationic polymerization initiator acts catalytically in light, even if it mixes with a curable adhesive, a curable adhesive is excellent in storage stability and workability.

The photocationic polymerization initiator is to generate a cationic species or Lewis acid by irradiation of active energy rays such as visible light, ultraviolet ray, X-ray or electron beam to initiate the polymerization reaction of the cationic polymerizable compound. The photocationic polymerization initiator may be any type, but specific examples thereof include aromatic diazonium salts; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-arene complexes;

As an aromatic diazonium salt, the following compounds are mentioned, for example.

Benzenediazonium hexafluoroantimonate,

Benzenediazonium hexafluorophosphate,

Benzenediazonium hexafluoroborate and the like.

As an aromatic iodonium salt, the following compounds are mentioned, for example.

Diphenyliodium tetrakis (pentafluorophenyl) borate,

Diphenyliodium hexafluorophosphate,

Diphenyliodium hexafluoroantimonate,

Di (4-nonylphenyl) iodium hexafluorophosphate and the like.

As an aromatic sulfonium salt, the following compounds are mentioned, for example.

Triphenylsulfonium hexafluorophosphate,

Triphenylsulfonium hexafluoroantimonate,

Triphenylsulfonium tetrakis (pentafluorophenyl) borate,

4,4'-bis [diphenylsulfonio] diphenylsulfide bishexafluorophosphate,

4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate,

4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluorophosphate,

7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,

7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,

4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfidehexafluorophosphate,

4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate,

4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenylsulfide tetrakis (pentafluorophenyl) borate and the like

In addition, examples of the iron-arene complex include the following compounds.

Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,

Cumene-cyclopentadienyl iron (II) hexafluorophosphate,

Xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide and the like.

These photocationic polymerization initiators can easily obtain a commercial item, for example, "KAYARAD PCI-220" and "KAYARAD PCI" sold by Nippon Gunpowder, respectively, as a brand name -620 "," UVI-6990 "sold by Union Carbide," UVACURE 1590 "sold by Daicel Scitec Co., Ltd.," ADEKAOPTOMER "SP- sold by ADEKA Co., Ltd. 150 "and" Adekaoptomer SP-170 "," CI-5102 "," CIT-1370 "," CIT-1682 "," CIP-1866S "," CIP-2048S "sold by Nippon Soda Co., Ltd. "And" CIP-2064S "," DPI-101 "," DPI-102 "," DPI-103 "," DPI-105 "," MPI-103 "," MPI- "sold by Midori Chemical Co., Ltd. 105 "," BBI-101 "," BBI-102 "," BBI-103 "," BBI-105 "," TPS-101, "TPS-102", "TPS-103", "TPS-105", "MDS-103", "MDS-105", "DTS-102" and "DTS-103", "PI-2074" sold by Rhodia, etc. are mentioned.

These photocationic polymerization initiators may be used independently, respectively and may be used in mixture of 2 or more types. Among these, aromatic sulfonium salts are particularly preferable because they have ultraviolet absorbing properties even in a wavelength range of 300 nm or more, which is excellent in curability and can provide a cured product having good mechanical strength and good adhesion between the polarizing film and the protective film. Is used.

The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to a total of 100 weight part of the cation polymeric compound containing an epoxy compound and an oxetane compound, Preferably it is 1-6 weight part. When there is little compounding quantity of a photocationic polymerization initiator, hardening becomes inadequate and there exists a tendency for the mechanical strength and adhesiveness between a polarizing film and a protective film to fall. On the other hand, when there are too many compounding quantities of a photocationic polymerization initiator, the ionic substance in hardened | cured material may increase and the hygroscopicity of hardened | cured material may become high and the durability performance of the adhesive bond layer obtained may fall.

In addition, a curable adhesive agent may contain the (meth) acrylic-type compound which is radically polymerizable with the said epoxy compound or with an epoxy compound and an oxetane compound. By using a (meth) acrylic compound together, the effect which raises the hardness and mechanical strength of an adhesive bond layer can be anticipated, Furthermore, adjustment of the viscosity, hardening rate, etc. of a curable adhesive agent can be performed much more easily.

As the (meth) acrylic compound, two or more kinds of (meth) acrylate monomers having at least one (meth) acryloyloxy group and a compound having a functional group can be obtained by reacting at least two (meth) acryl molecules in the molecule. (Meth) acrylate oligomer which has a) acryloyloxy group, etc. are mentioned. These may be used independently, respectively and may use 2 or more types together. When using 2 or more types together, 2 or more types of (meth) acrylate monomers may be sufficient, and 2 or more types of (meth) acrylate oligomers may be sufficient, Of course, 1 or more types of (meth) acrylate monomers and (meth) acryl You may use together 1 or more types of a late oligomer. In addition, "(meth) acrylate" means acrylate or methacrylate.

In the above-mentioned (meth) acrylate monomer, a monofunctional (meth) acrylate monomer having one (meth) acryloyloxy group in a molecule, and a bifunctional (meth) acryl having two (meth) acryloyloxy groups in a molecule There are polyfunctional (meth) acrylate monomers having three or more (meth) acryloyloxy groups in the rate monomer and in the molecule.

Specific examples of the monofunctional (meth) acrylate monomers include tetrahydroperferyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, 2- Hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylic Rate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, dicyclopentenyloxy Ethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, ethyl carbitol (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, phenoxy Li and the like can be mentioned ethylene glycol (meth) acrylate.

As a monofunctional (meth) acrylate monomer, the (meth) acrylate monomer containing a carboxyl group can also be used.

Monofunctional (meth) acrylate monomers containing a carboxyl group include 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylhexahydrophthalic acid, carboxyethyl (meth) acrylate, 2- (Meth) acryloyloxyethyl amber acid, N- (meth) acryloyloxy-N ', N'- dicarboxymethyl- p-phenylenediamine, 4- (meth) acryloyloxy ethyl trimellitic acid Etc. can be mentioned.

Examples of the difunctional (meth) acrylate monomers include alkylene glycol di (meth) acrylates, polyoxyalkylene glycol di (meth) acrylates, halogen substituted alkylene glycol die (meth) acrylates, Di (meth) acrylates of aliphatic polyols, di (meth) acrylates of hydrogenated dicyclopentadiene or tricyclodecanedialkanols, di (meth) acrylates of dioxane glycols or dioxane dialkanols And the di (meth) acrylates of the alkylene oxide adducts of bisphenol A or bisphenol F, epoxy di (meth) acrylates of bisphenol A or bisphenol F and the like.

More specific examples of the difunctional (meth) acrylate monomers include ethylene glycol di (meth) acrylate, 1,3-butanedioldi (meth) acrylate, 1,4-butanedioldi (meth) acrylate, 1,6-hexanedioldi (meth) acrylate, 1,9-nonanedioldi (meth) acrylate, neopentyl glycoldi (meth) acrylate, trimethylolpropanedi (meth) acrylate, Pentaerythritol di (meth) acrylate, ditrimethylolpropanedi (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol Di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol Di (meth) acrylate, 2,2-bis [4- (meth) acryloyloxy of di (meth) acrylate, silicone di (meth) acrylate, hydroxypivalic acid neopentyl glycol ester Methoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyldi (meth) acrylate, tricyclodecane dimethanol Di (meth) acrylate, 1,3-dioxine-2,5-diyldi (meth) acrylate [alias: dioxetine glycol di (meth) acrylate], hydroxy pivalaldehyde and trimethylol Di (meth) acrylate of acetal compound [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxine] with propane, Tris (hydroxyethyl) isocyanurate di (meth) acrylate and the like.

Examples of the trifunctional or higher polyfunctional (meth) acrylate monomer include glycerine tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, and ditrimethylol. Propane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol The poly (meth) acrylate of trifunctional or more than trifunctional aliphatic polyols, such as hexa (meth) acrylate, is typical, and the poly (meth) acrylate of the trifunctional or more than trifunctional halogen substituted polyol, and the alkylene oxide adduct of glycerin Tri (meth) of alkylene oxide adducts of meta) acrylate and trimethylolpropane Dimethacrylate, 1,1,1-tris [(meth) ethoxy with an oxy-acryloyl ethoxy] propane, tris (hydroxyethyl) isocyanurate tri (meth) acrylates.

On the other hand, a (meth) acrylate oligomer includes a urethane (meth) acrylate oligomer, a polyester (meth) acrylate oligomer, an epoxy (meth) acrylate oligomer and the like.

A urethane (meth) acrylate oligomer is a compound which has a urethane bond (-NHCOO-) and at least 2 (meth) acryloyloxy groups in a molecule | numerator. Specifically, a urethane-ized reaction product of a hydroxyl group-containing (meth) acrylate monomer and a polyisocyanate having at least one (meth) acryloyloxy group and at least one hydroxyl group, respectively, in a molecule, and a polyol is reacted with a polyisocyanate The urethane-ized reaction product of the terminal isocyanate group containing urethane compound obtained by making it, and the (meth) acrylate monomer which respectively has at least 1 (meth) acryloyloxy group and at least 1 hydroxyl group in a molecule | numerator can be used.

As a hydroxyl-containing (meth) acrylate monomer used for the said urethanation reaction, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate , 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycerine (meth) acrylate, trimethylolpropanedi (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol Penta (meth) acrylate etc. are mentioned.

As a polyisocyanate provided for the urethanation reaction with such a hydroxyl-containing (meth) acrylate monomer, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexyl methane diocyanate, tolylene diisocyanate, Diisocyanate (for example, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate etc.) obtained by hydrogenating xylene diisocyanate and aromatic isocyanate among these diisocyanate, triphenylmethane triisocyanate, dibenzylbenzene And polyisocyanates obtained by multiplying di- or tri-isocyanates such as triisocyanates and the above-mentioned diisocyanates.

Moreover, polyester polyol, polyether polyol, etc. can be used as polyols used in order to make terminal isocyanate group containing urethane compound by reaction with polyisocyanate, in addition to an aromatic, aliphatic, and alicyclic polyol. Aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, tri Methylolethane, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerol, hydrogenated bisphenol A, and the like. .

The polyester polyol is obtained by the dehydration condensation reaction of the above-mentioned polyols and polybasic carboxylic acid or its anhydride. When an example of a polybasic carboxylic acid or its anhydride is attached to "(anhydride)" which may be an anhydride, it is (anhydrous) pumpkin acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) Trimellitic acid, (anhydride) pyromellitic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, hexahydro (anhydride) phthalic acid, and the like.

The polyether polyol may be a polyoxyalkylene-modified polyol or the like obtained by the reaction of the above-described polyols or dihydroxybenzenes with alkylene oxide in addition to the polyalkylene glycol.

A polyester (meth) acrylate oligomer is a compound which has an ester bond and at least 2 (meth) acryloyloxy group in a molecule | numerator. Specifically, it can obtain by the dehydration condensation reaction using (meth) acrylic acid, polybasic carboxylic acid or its anhydride, and a polyol. Examples of the polybasic carboxylic acid or its anhydride used in the dehydration condensation reaction are denoted by "(anhydride)", which may be anhydride, (anhydrous) amber acid, adipic acid, (anhydrous) maleic acid, (anhydrous) Itaconic acid, trimellitic acid (anhydride), pyromellitic acid (anhydride), hexahydro (anhydride) phthalic acid, (anhydride) phthalic acid, isophthalic acid, terephthalic acid, and the like. In addition, as the polyol used in the dehydration condensation reaction, 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentylglycol Kohl, trimethylolethane, trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerine, hydrogenated bisphenol A and the like Can be mentioned.

An epoxy (meth) acrylate oligomer can be obtained by addition reaction of polyglycidyl ether and (meth) acrylic acid, and has at least two (meth) acryloyloxy groups in a molecule | numerator. Examples of the polyglycidyl ether used for the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, and 1,6-hexanediol di. Glycidyl ether, bisphenol A diglycidyl ether, etc. are mentioned.

When mix | blending a (meth) acrylic-type compound with a curable adhesive agent, it is preferable that the quantity shall be 20 weight% or less, More preferably, 10 weight% or less based on the quantity of the whole active energy ray curable compound. When the compounding quantity of a (meth) acrylic-type compound increases, there exists a tendency for the adhesiveness between a polarizing film and a protective film to fall.

When a curable adhesive contains radically polymerizable compounds, such as a (meth) acrylic-type compound as mentioned above, it is preferable that a radical photopolymerization initiator is mix | blended. As radical photopolymerization initiator, what is necessary is just to be able to start superposition | polymerization of radically polymerizable compounds, such as a (meth) acrylic-type compound by irradiation of an active energy ray, and a conventionally well-known thing can be used. Specific examples of the radical photopolymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, and 2- Acetophenone-based initiators such as methyl-1- [4- (methylthio) phenyl-2-morpholinopropane-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; Benzophenone series initiators such as benzophenone, 4-chlorobenzophenone and 4,4'-diaminobenzophenone; Benzoin ether type initiators, such as benzoin propyl ether and benzoin ethyl ether; Thioxanthone initiators such as 4-isopropyl thioxanthone; Others, xanthone, fluolenone, camphor quinone, benzaldehyde, anthraquinone and the like.

The compounding quantity of a radical photopolymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of radically polymerizable compounds, such as a (meth) acrylic-type compound, Preferably it is 1-6 weight part. When there is little quantity of radical photopolymerization initiator, hardening becomes inadequate and there exists a tendency for mechanical strength and adhesiveness of a polarizing film and a protective film to fall. In addition, when there is too much quantity of radical photopolymerization initiator, the active energy ray curable compound (radical polymerizable compounds, such as a cationic polymerizable curable compound containing an epoxy compound and a (meth) acrylic-type compound) in a curable adhesive agent becomes comparatively small, and is obtained There exists a possibility that the durability of an adhesive bond layer may fall.

Curable adhesive agent can contain a photosensitizer further as needed. By mix | blending a photosensitizer, the reactivity of cationic polymerization and / or radical polymerization becomes high, and the mechanical strength of an adhesive bond layer, and the adhesiveness between a polarizing film and a protective film can be improved. As a photosensitizer, a carbonyl compound, an organic sulfur compound, a persulfide, a redox type compound, an azo and diazo compound, a halogen compound, a photoreducing dye etc. are mentioned, for example. More specific examples of photosensitizers include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether and α, α-dimethoxy-α-phenylacetophenone; Benzophenones such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzate, 4,4'-bis (dimethylamino) benzophenone and 4,4'-bis (diethylamino) benzophenone derivative; Thioxanthone derivatives such as 2-chlorothioxanthone or 2-isopropylthioxanthone; Anthraquinone derivatives such as 2-chloroanthraquinone or 2-isopropylthioxanthone; Acridon derivatives such as N-methylacridone or N-butylacridone; Others include α, α-diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compounds, halogen compounds and the like. These photosensitizers may be used independently, respectively and may be used in mixture of 2 or more types. It is preferable to mix | blend a photosensitizer in the ratio of 0.1-20 weight part with 100 weight part of whole active energy ray curable compounds.

You may add the well-known polymer additive normally used for a polymer to curable adhesive agent. Examples thereof include primary antioxidants such as phenolic and amine based, sulfur secondary antioxidants, hindered amine based light stabilizers (HALS), benzophenone based, benzotriazole based or ultraviolet absorbents such as benzoate based.

Curable adhesive may further contain a solvent as needed. The solvent is appropriately selected in consideration of the solubility of the components constituting the curable adhesive. Examples of common solvents include aliphatic hydrocarbons such as n-hexane and cyclohexane; Aromatic hydrocarbons such as toluene and xylene; Alcohols such as methanol, ethanol, propanol, isopropanol and n-butanol; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; Esters such as methyl acetate, ethyl acetate and butyl acetate; Cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; Halogenated hydrocarbons such as methylene chloride and chloroform; The compounding ratio of a solvent is suitably determined from a viewpoint of viscosity adjustment by the objective on processing, such as film-forming property.

[Second protective film]

As described above, when the cycloolefin-based resin film is bonded to one side of the polarizing film, a second protective film containing another thermoplastic resin may be bonded to the opposite side of the polarizing film. The second protective film containing the thermoplastic resin is also bonded to the polarizing film through an adhesive. The 2nd protective film is suitable suitably widely used as a forming material of a protective film conventionally in this field, such as a cellulose acetate resin, a polyolefin resin, an acrylic resin, a polyimide resin, a polycarbonate resin, polyester resin, etc., for example. It can consist of a material. It is preferable to use a cellulose acetate resin film as a 2nd protective film among these from a viewpoint of mass productivity and adhesiveness. A cellulose acetate resin film is used suitably as a 2nd protective film also from a viewpoint of the ease of providing a surface treatment layer, and an optical characteristic.

An acetate cellulose resin film is a film which consists of a part of cellulose or a complete acetate ester, and a triacetyl cellulose film, a diacetyl cellulose film, etc. are mentioned, for example. As such a cellulose acetate resin film, a suitable commercial item, for example, "Fujitak TD80", "Fujitaek TD80UF" and "Fujitaek TD80UZ" sold by Fujifilm Co., Ltd., is sold by Konica Minolta Opto Co., Ltd. "KC8UX2M", "KC8UY", "KC4UEW", and the like (above, all trade names) can be used.

The adhesive used for bonding the second protective film and the polarizing film is not particularly limited, and various adhesives used as the adhesive used when pasting the polarizing film and the cycloolefin resin film can be used in the same manner. It is preferable to use the same thing as the adhesive agent used for a system resin film. When sticking these films using an adhesive agent, in order to improve adhesiveness, the surface treatment for adhesive improvement mentioned above may be suitably given to the adhesive surface of a 2nd protective film and / or a polarizing film bonded to it. When a 2nd protective film is comprised from a cellulose acetate resin film and sticks to a polarizing film using an aqueous adhesive agent, a saponification process is mentioned as one of the preferable surface treatments performed on this cellulose acetate resin film. The saponification treatment is carried out by immersing the film in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide.

Although it is preferable that a 2nd protective film is thin, when it is too thin, there exists a tendency for intensity | strength to fall and workability falls, and on the other hand, when it is too thick, transparency falls or a weight of a polarizing plate tends to become large. From this point of view, the thickness of the second protective film is usually 10 to 200 µm, preferably 20 to 150 µm, and more preferably 30 to 100 µm, when the thickness of the second protective film is composed of cellulose acetate-based resin.

Surface treatment, such as an anti-glare process, a hard-coating process, an antistatic process, an antireflective process, may be given to the surface on the opposite side to the surface affixed on a polarizing film.

[Polarizing Plate Manufacturing Method]

Next, the manufacturing method of the polarizing plate which concerns on this invention is demonstrated. As described above, in the present invention, a polarizing plate is manufactured by bonding a protective film containing a cycloolefin-based resin to a polarizing film through an adhesive. If desired, a first protective film comprising a cycloolefin-based resin is bonded to one side of the polarizing film, and a second protective film containing a separate thermoplastic resin is formed on the other side of the polarizing film through an adhesive. Can be bonded. And before joining to a polarizing film, the protective film containing cycloolefin resin is made to contact the organic solvent which does not contain a solute substantially in the range whose haze value of the cycloolefin resin film does not exceed 0.5%. . In this specification, the process which contacts this organic solvent can be called "solvent process."

In one aspect, the organic solvent used for the solvent treatment is an organic solvent that changes the cycloolefin-based resin when the cycloolefin-based resin constituting the first protective film described above is alone. Solvent) and an organic solvent (hereinafter, referred to as " poor solvent ") that does not substantially change the cycloolefin resin when contacted with the cycloolefin resin alone. .

Whether an organic solvent corresponds to a good solvent or a poor solvent with respect to a cycloolefin resin film can be determined by the following test. First, the cycloolefin resin film used as a protective film is cut out, about 1.0 g is taken, it is correctly weighed to three decimal places by gram unit, and the mass is called Fg. In addition, about 990 g of the organic solvent is accurately weighed to three digits after the decimal point in grams, and its mass is called Sg. The resin film weighed precisely and accurately from the above organic solvent is completely immersed and left to stand for 24 hours. After 24 hours, it is observed that there is no change in the shape and appearance of the immersed resin film. In addition, about 10.0 g of the supernatant liquid of the organic solvent in which the resin film was immersed is measured, and also it weighs precisely and correctly to three digits after the decimal point in gram unit, and the mass is called Lg. The organic solvent is dried and removed therefrom, the remaining solid content is weighed and its mass is referred to as Rg. The amount of melt | dissolution of a resin film is calculated | required from these values. When the resin film is completely dissolved, it becomes a solution of [F (= about 1g) / {F + S (= about 100g)} × 100% by weight] (= about 1% by weight), and after drying, the solid content is [L ( = About 10 g) × F (= about 1 g) / {F + S (= about 100 g)} g] (= about 0.1 g). Therefore, the dissolution rate of a resin film is computed from following formula (III).

Thus, when the resin film after immersing in the organic solvent for 24 hours does not cause a change in a shape and an external appearance, and a dissolution rate is less than 1 weight%, the organic solvent is called a poor solvent. In other cases, that is, when a change in shape or appearance is caused, or when the dissolution rate is 1% by weight or more, the organic solvent is referred to as a good solvent. Of course, a change in shape and appearance is caused, and even when the solubility is 1% by weight or more, the organic solvent becomes a good solvent. According to the experiment, in the state which did not melt | dissolve but brought about the change in the shape and appearance of a film, there existed a state in which a film swelled and cannot maintain a round shape, and a state in which the film whitened.

Representative data among experiments performed on a plurality of organic solvents using a stretched cycloolefin-based resin film (trade name "Zeonor Film", manufactured by Nihon Xeon Co., Ltd.) used in Examples described later as a sample are summarized in Table 1 below. It was shown. "%" Indicating solubility in the table is based on weight as can be seen in the above description. In addition, when the "dissolution rate" column is "-", it means that only the immersion experiment was performed and the appearance after 24 hours immersion was observed, but not until the measurement of the dissolution rate. In all, the solubility is estimated to be approximately zero from the results of appearance observation after 24 hours.

solvent Solubility Changes after immersion Good solvent
toluene
Xylene
Cyclohexane
Methylcyclohexane
Ethylcyclohexane
Hexane
Heptane
Pentane
Tetrahydrofuran
Diethyl ether
Dichloromethane
chloroform
6%
14%
98%
100%
99%
Less than 1%
Less than 1%
-
Less than 1%
-
Less than 1%
8%
swelling
swelling
Dissolution
Dissolution
Dissolution
all sorts of flowers
all sorts of flowers
all sorts of flowers
all sorts of flowers
all sorts of flowers
all sorts of flowers
swelling Poor solvent
Methyl ethyl ketone
Methyl Isobutyl Ketone
Cyclohexanone
Ethyl acetate
Isopropyl Acetate
Propyl acetate
Butyl acetate
Isopropanol
Butanol
Less than 1%
Less than 1%
Less than 1%
Less than 1%
Less than 1%
Less than 1%
Less than 1%
Less than 1%
Less than 1%
No change
No change
No change
No change
No change
No change
No change
No change
No change

According to these results and the present experiences of the present inventors, alicyclic hydrocarbons, such as cyclohexane, methylcyclohexane, and ethylcyclohexane, are classified as a good solvent because the dissolution rate of cycloolefin resin becomes near 100%. In addition, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane and chloroform, aliphatic ethers such as diethyl ether and tetrahydrofuran and aliphatic hydrocarbons such as pentane, hexane and heptane are cycloolefins. There are ones in which the dissolution rate of the resin is 1% or more and less than 1%, and since both change the shape and appearance, they are also classified as good solvents.

On the other hand, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, aliphatic alcohols such as isopropanol and butanol, and aliphatic esters such as ethyl acetate, propyl acetate, isopropyl acetate and butyl acetate are selected from cycloolefin resins. It is classified as a poor solvent because it has a solubility of less than 1% and does not cause a change in the shape or appearance of the film.

It was found that alicyclic hydrocarbons, which are classified as good solvents by dissolving cycloolefin resins in the above-mentioned organic solvents, are effective in increasing adhesion to the polarizing film without excessive erosion of the cycloolefin resin even when used alone. Therefore, in another aspect of the present invention, the organic solvent used in the solvent treatment described above contains an alicyclic hydrocarbon. The alicyclic hydrocarbon may typically be a compound represented by the formula (I) mentioned above. In the case of using an alicyclic hydrocarbon, it is advantageous to use a mixed solvent containing a poor solvent in addition to the alicyclic hydrocarbon. It is preferable that the poor solvent mixed with an alicyclic hydrocarbon is an alkyl ester of an organic acid, and also the acetic acid ester mentioned above.

In this invention, it is very important to process a solvent so that a cycloolefin resin film may not be excessively eroded, and the haze value of the cycloolefin resin film after a solvent process is employ | adopted as an index of not being excessively eroded. When erosion of the surface of the cycloolefin resin film proceeds, the adhesion to the polarizing film is improved, but the optical performance of the cycloolefin resin film is impaired. Therefore, a solvent process is carried out so that the haze value of the cycloolefin resin film after a process may not exceed 0.5%. It is much more preferable that the haze value at this time does not exceed 0.3% and further does not exceed 0.2%. The haze value is defined in JIS K 7136: 2000 "Calculation method of the haze of a plastic-transparent material", and is a value defined by (diffusion transmittance / total light transmittance) × 100 (%).

Moreover, when erosion advances by a solvent process, retardation of a film will cancel and there exists a tendency for in-plane retardation value to fall. Therefore, when a cycloolefin resin film is extended | stretched and the in-plane phase difference value is provided, it is also effective to make the amount of change of the in-plane phase difference value of the cycloolefin resin film by a solvent process into the index of not excessively eroding. Specifically, when the cycloolefin-based resin film has an in-plane retardation value of 30 nm or more before the solvent treatment, the in-plane retardation value after the solvent treatment does not exceed 3 nm more than the in-plane retardation value before the solvent treatment, in other words, the solvent treatment It is preferable to perform a solvent process so that the fall amount (in-plane retardation value before a solvent process-in-plane retardation value after a solvent process) of the in-plane retardation value after a solvent process with respect to an in-plane retardation value may be 3 nm or less. It is much more preferable that the amount of reduction of the in-plane retardation value after the solvent treatment to the in-plane retardation value before the solvent treatment is 2.5 nm or less, particularly 2 nm or less. When this fall amount is large, the possibility of affecting display characteristics arises when the obtained polarizing plate is applied to a liquid crystal display device. When the alicyclic hydrocarbon is used alone in the solvent treatment, the amount of decrease in the in-plane retardation value tends to be slightly increased, and it is preferable to use a poor solvent in addition to the alicyclic hydrocarbon in this respect.

In-plane retardation value (Re) of the film are the following expression to say that the in-plane refractive index in the slow axis direction of the film, n _x, the refractive index in the in-plane fast axis direction (direction perpendicular in the slow axis and the in-plane) n _y, the thickness d It is a value defined by (IV), and can measure using a commercially available various phase difference meter.

Re = (n _x -n _y ) × d (IV)

When using a mixed organic solvent, what is necessary is just to consider a haze value and an in-plane phase difference value of the cycloolefin resin film after a solvent process, and to determine a mixing ratio.

In this invention, a polarizing plate can be manufactured through the process of the following (i)-(iii). When bonding the 1st protective film containing cycloolefin resin to one side of a polarizing film, and bonding the 2nd protective film containing another thermoplastic resin to the other side of a polarizing film, the process of the following (iv) Hire more.

(i) a solvent treatment step of treating the surface of the cycloolefin resin film with the organic solvent substantially free of solutes described above;

(ii) a drying step of drying the organic solvent,

(iii) First bonding step of bonding the dried cycloolefin resin film treated with the organic solvent to the polarizing film through the adhesive such that the treated surface becomes the bonding surface.

(iv) 2nd bonding process of bonding the 2nd protective film which consists of a thermoplastic resin film to the surface on the opposite side to which the cycloolefin resin film of the said polarizing film was bonded through the adhesive agent.

In the solvent treatment step (i), the cycloolefin resin film is brought into contact with the organic solvent described above. Specifically, the method of apply | coating the organic solvent to the surface of a cycloolefin resin film is used preferably. The coating method used for this purpose can employ | adopt well-known methods, such as the casting method, the Meyer bar coating method, the gravure coating method, the comma coating method, the doctor blade method, the die coating method, the dip coating method, and the spray method. The surface to be treated may be either one surface or both surfaces of the cycloolefin resin film, but the surface bonded to the polarizing film is subjected to this treatment.

Next, in the drying step (ii), the organic solvent used to treat the surface of the cycloolefin resin film is dried. Although natural drying may be sufficient, when drying by applying heat, it is preferable to dry at the temperature below the glass transition point of a cycloolefin resin film from a viewpoint of preventing deformation of a film. This drying step (ii) may be carried out in parallel with the solvent treatment step (i), or may be performed in parallel as well, that is, drying the organic solvent when the cycloolefin resin film is treated with the organic solvent. It is desirable to carry out the operation simultaneously. Specifically, the method of apply | coating an organic solvent, etc. can be employ | adopted while blowing in a coated surface.

In said 1st bonding process (i), the cycloolefin resin film processed with the organic solvent is bonded to a polarizing film through an adhesive agent so that the process surface may become a bonding surface. The bonding method here is generally what is generally known, for example, a polarizing film and / or by a casting method, a Meyer bar coating method, a gravure coating method, a comma coating method, a doctor blade method, a die coating method, a dip coating method, a spraying method, or the like. The method of apply | coating an adhesive agent to the adhesive surface of the cycloolefin resin film joined thereon, and superimposing each other can be employ | adopted. In this case, the casting method is a method of spreading and applying the film to the surface while moving the film to be coated in a substantially vertical direction, a substantially horizontal direction, or both of them in an inclined direction. After apply | coating an adhesive agent, a polarizing film and a cycloolefin resin film are pinched and bonded together by a nip roll etc. In addition, when the adhesive is dropped between the films and then pressurized with a roll or the like to uniformly press and diffuse, the material of the roll to be used may be a metal or rubber, and the like may be used when passing between two rolls. Each roll may be the same material or different materials.

After bonding a cycloolefin resin film to a polarizing film through an adhesive agent, an adhesive layer is hardened by drying when an aqueous adhesive is used and irradiating an active energy ray when using a curable adhesive agent. The drying treatment can be performed, for example, by spraying hot air. The temperature is normally in the range of 40-100 degreeC, Preferably it exists in the range of 60-100 degreeC. Moreover, drying time is for 20 to 1,200 second normally. On the other hand, although the active energy ray used for active energy ray irradiation may be an ultraviolet-ray, an electron beam, an X-ray, a visible ray, etc., in general, an ultraviolet-ray is used preferably. The active energy ray may be irradiated with the strength and amount necessary to cure the adhesive layer.

When bonding the 2nd protective film containing a separate thermoplastic resin to the polarizing film surface on the opposite side to the surface to which a cycloolefin resin film is bonded, the said 2nd bonding process (iv) is further performed. In this step, the same method as in the above-described first joining step can be adopted. It is preferable that 2nd joining process (iv) is performed simultaneously with said 1st joining process (iii).

Although the thickness of the adhesive bond layer obtained after drying or hardening is about 0.01-5 micrometers normally, when an aqueous adhesive agent is used, it can be 1 micrometer or less. On the other hand, even when using a curable adhesive agent, it is preferable to set it as 2 micrometers or less. If the adhesive layer is too thin, the adhesion may be insufficient, while on the other hand, if the adhesive layer is too thick, there is a possibility of causing a poor appearance of the polarizing plate.

[Polarizing Plate]

The polarizing plate obtained in this way can improve the adhesive force between a polarizing film and a cycloolefin resin film. That is, the protective film containing a cycloolefin resin is bonded to the polarizing film in which a dichroic dye is adsorbed-oriented to polyvinyl alcohol-type resin through an adhesive agent, and the protective film containing the said cycloolefin resin has the haze value. A polarizing plate bonded to the polarizing film through the adhesive in the state of being treated with the organic solvent described above in the range not exceeding 0.5%, and having an adhesive force to the polarizing film through the adhesive being 0.5 N / 25 mm or more. Can be. Moreover, the 1st protective film which consists of cycloolefin resin in the one side surface of the polarizing film by which a dichroic dye is adsorbed-oriented in polyvinyl alcohol-type resin, and the 2nd protective film which contains a thermoplastic resin in the other side surface of a polarizing film Each of the first protective films, which are bonded through the adhesives and each of the cycloolefin-based resins, is treated with the aforementioned organic solvent in a range in which the haze value does not exceed 0.5%, and the polarized light through the adhesives. A polarizing plate bonded to the film and having an adhesive force to the polarizing film through the adhesive is 0.5 N / 25 mm or more can also be obtained. In any polarizing plate, the adhesive force of the first protective film containing the cycloolefin resin to the polarizing film through the adhesive is more preferably 0.7 N / 25 mm or more, more preferably 0.8 N / 25 mm or more.

Here, the adhesive force with respect to the polarizing film of a cycloolefin resin film is a value measured as follows. That is, as described so far, the first protective film containing the cycloolefin resin on one side of the polarizing film is made of a separate thermoplastic resin on the other side of the polarizing film, and is polarized than the cycloolefin resin film described above. A second protective film having a large adhesion to the film is bonded to each other through an adhesive, and if necessary, the adhesive is further dried or cured to produce a polarizing plate. An adhesive layer is provided in the cycloolefin resin film side. After cutting the test piece of width 25mm x length about 200mm from the polarizing plate provided with the adhesive obtained in this way, the adhesive surface was bonded to a glass plate, the adhesive force of the adhesive with respect to a glass plate is fully raised, and the longitudinal direction of a test piece was used using the tensile tester. Holding the second protective film and the polarizing film of one end (one side of 25 mm in width), the JIS K 6854-1: 1999 " A 90 ° peel test in accordance with Adhesive- Peel Adhesion Strength Test Method-Part 1: 90 Degree Peeling is performed. The average peel force (unit: N / 25mm) at this time is called adhesive force with respect to the polarizing film of a cycloolefin resin film.

When this adhesive force is too small, it peels off at the interface of a polarizing film and a cycloolefin resin film, and after attaching a polarizing plate to a liquid crystal cell as mentioned above, when only the rework arises, only a cycloolefin resin film is formed on a liquid crystal cell. Can be left on. On the other hand, although this adhesive force is so preferable that it is large, when it tries to make it large, the processing (erosion) of the cycloolefin resin film by an organic solvent will become excessive, and an optical characteristic will be impaired, such as raising the haze value of a cycloolefin resin film. Therefore, it is important to improve the adhesive force with respect to the polarizing film of a cycloolefin resin film by performing a solvent process, maintaining the optical characteristic including haze value of a cycloolefin resin film.

The polarizing plate obtained by this invention can provide an adhesive layer in the surface on the opposite side to the polarizing film of the cycloolefin resin film bonded to the polarizing film. This adhesive layer can be used for the bonding to the liquid crystal cell of this polarizing plate, the bonding to another functional film, such as a retardation film, and the bonding to another layer. As an adhesive, what used the base polymer as an acryl-type polymer, a silicone type polymer, polyester, a polyurethane, a polyether, etc. can be used. Among them, the acrylic adhesive has excellent optical transparency, maintains proper wettability and cohesion, and has excellent adhesiveness, and also has weather resistance and heat resistance, and does not cause peeling problems such as floating or peeling under conditions of heating or humidification. It is preferable to select and use the thing. In the acrylic pressure sensitive adhesive, a functional group-containing acrylic monomer composed of alkyl ester of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl group, ethyl group or butyl group, and (meth) acrylic acid, (meth) acrylic acid hydroxyethyl, etc. Is preferably 25 ° C. or lower, more preferably 0 ° C. or lower, and an acrylic copolymer having a weight average molecular weight of 100,000 or more is useful as the base polymer.

Formation of the pressure-sensitive adhesive layer, for example, by dissolving or dispersing the pressure-sensitive adhesive composition including the base polymer in an organic solvent such as toluene or ethyl acetate to prepare a solution of 10 to 40% by weight, and the pressure-sensitive adhesive layer is formed on the protective film It can carry out by the method etc. which form an adhesive layer by moving it on a polarizing plate. It is common to mix | blend a crosslinking agent in addition to the base polymer mentioned above for an adhesive. Moreover, when intending joining to a liquid crystal cell, it is also preferable to mix | blend a silane coupling agent. Although the thickness of an adhesive layer is determined according to the adhesive force etc., it is usually the range of 1-50 micrometers.

If necessary, a filler made of inorganic powder such as glass fiber, glass beads, resin beads, metal powder, or the like, a pigment, a colorant, an antioxidant, an ultraviolet absorber, or the like may be blended. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex salt compounds and the like.

Example

Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, parts and percentages indicating the amount to amount used are based on weight unless otherwise specified. In addition, the in-plane retardation value and the thickness direction retardation value of a film are the values measured by the rotational analyzer method with monochromatic light of wavelength 559nm using the retardation measuring apparatus "KOBRA-21ADH" of Oshi Measurement Instruments Co., Ltd. product.

Production Example 1 Preparation of Polarizing Film

After dipping a polyvinyl alcohol film having an average degree of polymerization of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm in pure water at 30 ° C., 30 ° C. in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.02 / 2/100 Dipped in and dyed. Thereafter, boric acid treatment was performed by immersion at 56.5 ° C. in an aqueous solution having a weight ratio of 12/5/100 of potassium iodide / boric acid / water. Subsequently, after wash | cleaning with the pure water at 8 degreeC, it dried at 65 degreeC and obtained the polarizing film of about 30 micrometers in thickness which iodine adsorption-aligned to polyvinyl alcohol. Stretching was mainly carried out in iodine staining and boric acid treatment, with a total draw ratio of 5.3 times.

Preparation Example 2 Preparation of Adhesive Composition

Acetacetyl-modified polyvinyl alcohol (trade name "Gosepamer Z-200", manufactured by Nihon Synthetic Chemical Industries, Ltd., viscosity of 4% aqueous solution = 12.4 mPasec, saponification degree: 99.1 mol%) was dissolved in pure water. A 10% aqueous solution was prepared. The aqueous acetacetyl-modified polyvinyl alcohol solution and sodium glyoxylate serving as a crosslinking agent are mixed so that the former: latter solid content ratio is 1: 0.1, and acetacetyl-modified polyvinyl alcohol is added 2.5 parts by weight to 100 parts of water. The adhesive composition was prepared by diluting with pure water as much as possible.

[Control]

(A) protective film

Corona treatment was performed on one side of a stretched cycloolefin resin film (trade name "Zeonor Film, manufactured by Nihon Xeon Co., Ltd., in-plane retardation value = 90 nm, thickness direction retardation value = 79 nm") having a thickness of 25 μm, and used as a protective film on one side. Haze value of this film was haze transmittance meter based on JIS K 7361-1: 1997 "Test method of the total light transmittance of a plastics-transparent material-Part 1: Single beam method" [Murakami Color Technology Research Institute make The result was measured using "HR-100"], and the result was shown in Table 2. In addition, the corona treatment was given to one surface of the 40-micrometer-thick cellulose acetate-based resin film (brand name "KC4UEW", Konica Minolta Opto Corporation). To another protective film.

(B) Preparation of Polarizing Plate

The adhesive composition prepared in Preparation Example 2 was applied to both surfaces of the polarizing film produced in Production Example 1 in an atmosphere of 23 ° C., and the stretched cycloolefin-based resin film treated with the corona treatment was applied to the adhesive coating surface on one side, and the adhesive coating surface on the other side was The corona-treated cellulose acetate-based resin film was bonded using an adhesive device ("LPA3301" manufactured by Fuji Plastics Co., Ltd.) so that each corona-treated surface became a bonding surface with a polarizing film. This was dried for 5 minutes at 80 degreeC, and the polarizing plate was produced.

(C) evaluation of adhesion

After performing the corona treatment on the cycloolefin resin film surface of the polarizing plate produced above, the acryl-type adhesive sheet was bonded to the corona treatment surface. Cutting a test piece of the obtained pressure-sensitive adhesive portion polarizing plate width 25mm, length of about 200mm, and performing after the adhesive surface is bonded to the soda glass, the pressing treatment for 20 minutes at a pressure of 5kgf / cm ^2, temperature 50 ℃ of the autoclave, and Again, it was left to stand in the atmosphere of temperature 23 degreeC, and 60% of a relative humidity for one day. In this state, the cellulose acetate-based resin film and the polarizing film of the longitudinal direction (one side of width 25mm) of the test piece were hold | maintained using the universal tensile tester ("AG-1" by Shimadzu Corporation), and the temperature was 23 degreeC. To 90 ° peel test (JIS K 6854-1: 1999 "Adhesive-peel adhesion strength test method-Part 1: 90 degree peeling" at 200mm / min crosshead speed (grip movement speed) under an atmosphere of 60% relative humidity) Standard), and the adhesive force between a cycloolefin resin film and a polarizing film was evaluated. The results are shown in Table 2.

Example 1

Toluene: methyl ethyl ketone = 1: 9 (volume ratio) using a coating machine (bar coater manufactured by Daiichi Rika Co., Ltd.) on one side of the stretched cycloolefin resin film used as the protective film on one side in the comparative example. The mixed organic solvent was coated. This potters performed wind blowers on the surface. The haze value of the cycloolefin resin film after a process was measured by the method shown to (A) of a comparative example, and the result was shown in Table 2.

Moreover, when the surface nonuniformity of the cycloolefin resin film after a solvent process was observed visually, although it was not seen clearly, it was a state which could confirm a nonuniformity when observed well. Similarly, the in-plane retardation value was measured for the cycloolefin resin film after the solvent treatment, and the change from the value before the treatment (90 nm) (minus the case where the retardation value was lower than before the treatment) was found. 0.3 nm. In the following Examples and Comparative Examples, the cycloolefin resin film after the solvent treatment was also subjected to the measurement of haze value, observation of surface unevenness and measurement of in-plane retardation value in the same manner as in the present example, and the haze value was defined as "haze" in Table 2. In the column of "value", the surface unevenness is evaluated in three steps as follows, and the results are evaluated in the "non-uniformity" column of Table 2, and the change of the in-plane retardation value from the film before the treatment in the column of "Re change" of Table 2, respectively. Indicated.

(Evaluation standard of the surface nonuniformity of the film after solvent processing)

None: no nonuniformity could be identified.

Weak: It is not clearly seen, but when observed well, the nonuniformity can be confirmed (state of Example 1).

Strong: Non-uniformity can be clearly confirmed.

In this way, the solvent-treated surface of the solvent-treated stretched cycloolefin resin film is subjected to corona treatment, and then used for bonding to one side of the polarizing film, and the other side of the polarizing film is corona-treated with the same corona treatment as the control example. The system resin film was bonded together, and the others produced the polarizing plate by the method similar to a comparative example. The adhesive force between the cycloolefin resin film and polarizing film of the obtained polarizing plate was evaluated by the method similar to (C) of a comparative example, and the result was shown in Table 2.

[Example 2]

A polarizing plate was produced and evaluated in the same manner as in Example 1 except that the mixed solvent was changed to toluene: methyl ethyl ketone = 2: 8 (volume ratio). The haze value of the cycloolefin resin film after a solvent process, the observation result of surface nonuniformity, the change of in-plane phase difference value, and the adhesive force between the cycloolefin resin film of a polarizing plate and a polarizing film were put together in Table 2, and were shown.

Comparative Example 1

The polarizing plate was produced and evaluated by the method similar to Example 1 except having changed the mixed solvent to toluene: methyl ethyl ketone = 3: 7 (volume ratio). The haze value of the cycloolefin resin film after a solvent process, the observation result of surface nonuniformity, the change of in-plane phase difference value, and the adhesive force between the cycloolefin resin film of a polarizing plate and a polarizing film were put together in Table 2, and were shown.

Example 3

Cyclohexane was coated on one side of the same stretched cycloolefin-based resin film used in Example 1 as the protective film in Example 1 using the same coating machine as in Example 1, and solvent treatment was performed. Here, since the cyclohexane had already evaporated and dried after completion of coating, it was not performed to blow the wind with the blower. The haze value of the cycloolefin resin film after a solvent process, the observation result of surface nonuniformity, and the change of the in-plane phase difference value were put together in Table 2, and were shown. In addition, after performing a corona treatment to the solvent process surface of the extending | stretching cycloolefin resin film processed by cyclohexane in this way, it is used for joining to one side of a polarizing film, except the polarizing plate by the method similar to Example 1 Made. The adhesive force between the cycloolefin resin film and polarizing film of the obtained polarizing plate was evaluated by the method similar to Example 1, and the result was shown in Table 2.

Example 4

Methylcyclohexane was applied to one side of the same stretched cycloolefin resin film as that used as the protective film on one side in Example 1 using the same coating machine as in Example 1 to carry out a solvent treatment. In this example, coating was carried out with a blower blown on the coating surface. The haze value of the cycloolefin resin film after a solvent process, the observation result of surface nonuniformity, and the change of the in-plane phase difference value were put together in Table 2, and were shown. In addition, after performing a corona treatment to the solvent process surface of the extending | stretching cycloolefin resin film processed with methylcyclohexane in this way, it is used for joining to one side of a polarizing film, except the polarizing plate by the method similar to Example 1 Made. The adhesive force between the cycloolefin resin film and polarizing film of the obtained polarizing plate was evaluated by the method similar to Example 1, and the result was shown in Table 2.

[Example 5]

The same experiment as in Example 4 was carried out except that the organic solvent was changed to ethylcyclohexane, and the results are summarized in Table 2.

[Examples 6 to 13]

The organic solvent is a mixed solvent of methylcyclohexane or ethylcyclohexane as a good solvent and ethyl acetate, isopropyl acetate, or propyl acetate as poor solvents, and the respective combinations and volume ratios are as shown in Table 2, and the others are the examples. The same experiment as in 4 was carried out, and the results are shown in Table 2.

EXAMPLE 14 AND 15

An organic solvent was used as a mixed solvent of heptane as a good solvent and methyl ethyl ketone as a poor solvent. The volume ratio of both was as shown in Table 2, and the same experiment as in Example 4 was conducted, and the results are summarized in Table 2. Indicated.

Comparative Example 2

The organic solvent was changed to heptane, and the others were carried out in the same experiment as in Example 4, and the results are shown in Table 2.

Yes No.
Treatment solution
(Volume in parentheses) Film after treatment
Adhesion

Haze value Heterogeneity Re change Control Example (Not processed) 0.1% - - 0.22N / 25mm Example 1
Example 2 Toluene: methyl ethyl ketone (1: 9)
Toluene: methyl ethyl ketone (2: 8) 0.1%
0.1% weakness
weakness -0.3nm
-0.5nm 0.82N / 25mm
1.91N / 25mm Comparative Example 1 Toluene: methyl ethyl ketone (3: 7) 0.6% Strong -1.2nm Non-peelable Example 3
Example 4
Example 5
Example 6
Example 7
Example 8

Example 9

Example 10

Example 11
Example 12
Example 13
Example 14
Example 15 Cyclohexane
Methylcyclohexane
Ethylcyclohexane
Methylcyclohexane: ethyl acetate (5: 5)
Ethylcyclohexane: ethyl acetate (2: 8)
Ethylcyclohexane: Isopropyl Acetate (1: 9)
Ethylcyclohexane: isopropyl acetate (2: 8)
Ethylcyclohexane: isopropyl acetate (3: 7)
Ethylcyclohexane: propyl acetate (2: 8)
Ethylcyclohexane: propyl acetate (3: 7)
Ethylcyclohexane: propyl acetate (4: 6)
Heptane: methyl ethyl ketone (8: 2)
Heptane: methyl ethyl ketone (9: 1) 0.1%
0.1%
0.1%
0.1%
0.1%
0.1%

0.1%

0.1%

0.1%
0.1%
0.1%
0.1%
0.3% none
none
none
none
none
none

none

none

none
none
none
weakness
weakness -2.2nm
-5.6nm
-9.1nm
-0.3nm
-0.8nm
-0.2nm

-0.4nm

-1.1 nm

-0.4nm
-1.2nm
-2.2nm
-0.3nm
-0.5nm 0.84N / 25mm
1.83N / 25mm
1.91N / 25mm
1.40N / 25mm
Non-peelable
0.61N / 25mm

2.92N / 25mm

Non-peelable

0.83N / 25mm
3.74N / 25mm
3.75N / 25mm
0.65N / 25mm
0.69N / 25mm Comparative Example 2 Heptane 0.5% Strong -0.8nm 0.77N / 25mm

As shown in Table 2, in the comparative example using the cycloolefin resin film which does not perform a solvent process, the adhesive force between a polarizing film and a cycloolefin resin film is low. On the other hand, in Comparative Example 1 in which the ratio of toluene in the toluene / methylethyl ketone mixed solvent used for the solvent treatment was increased to easily erode the cycloolefin resin film, the adhesive force between the polarizing film and the cycloolefin resin film was increased, The haze value of an olefin resin film increases to 0.6%, and cannot satisfy the optical characteristic at the time of polarizing plate. In contrast, in Examples 1 and 2 in which the ratio of toluene in the toluene / methylethyl ketone mixed solvent used for the solvent treatment was 10% by volume or 20% by volume, the haze value of the cycloolefin resin film was lower than 0.1%. The adhesive force between a polarizing film and a cycloolefin resin film can be improved, maintaining as it is.

In addition, in Examples 3 to 5 in which cyclohexane, methylcyclohexane, or ethylcyclohexane were used for the solvent treatment, the polarizing film and the cycloolefin system were maintained with the haze value of the cycloolefin resin film at a low value of 0.1%. The adhesive force between resin films can be raised. However, in these examples, especially Example 4 using methyl cyclohexane for solvent treatment, and Example 5 using ethyl cyclohexane, there exists a tendency for the fall of the in-plane phase difference value of a cycloolefin resin film to become slightly large by a solvent treatment. On the other hand, in Examples 6 to 13 in which acetic acid esters as poor solvents were mixed with these alicyclic hydrocarbons as good solvents, the polarizing film and the cycloolefin resin film were suppressed while the reduction of the in-plane retardation value of the cycloolefin resin film was reduced to 3 nm or less. Can increase the adhesion. In Examples 3 to 13 using alicyclic hydrocarbons, generation of nonuniformity after solvent treatment is suppressed compared to Examples 1 and 2 using toluene, and the polarizing film is maintained while maintaining the good appearance and visibility of the cycloolefin resin film. Adhesion can be increased.

In Comparative Example 2 in which the solvent was treated using a good solvent heptane, the adhesion between the polarizing film and the cycloolefin resin film is high, but the haze value of the cycloolefin resin film is increased to 0.5%, and surface unevenness is also observed after the treatment. The optical characteristics at the time of polarizing plate cannot be satisfied. In contrast, in Examples 14 and 15 in which heptane was mixed with methyl ethyl ketone as a poor solvent, surface unevenness was improved, and the polarization film and The adhesive force between cycloolefin resin films can be raised.

Claims (13)

As a method of manufacturing a polarizing plate by bonding a protective film containing a cycloolefin resin to a polarizing film having a dichroic dye adsorbed on a polyvinyl alcohol-based resin through an adhesive agent,
The protective film comprising the cycloolefin-based resin is substantially a mixture of an organic solvent that does not substantially change the cycloolefin-based resin by contact with an organic solvent that changes the cycloolefin-based resin by contact. The manufacturing method of the polarizing plate containing contacting to the said polarizing film through the said adhesive agent, after making contact with the mixed organic solvent which does not contain and the haze value of the said protective film not to exceed 0.5%. A first protective film containing a cycloolefin resin on one side of the polarizing film where dichroic dye is adsorbed and oriented to the polyvinyl alcohol resin, and a second protective film containing thermoplastic resin on the other side of the polarizing film, respectively. As a method of manufacturing a polarizing plate by bonding through an adhesive,
The first protective film containing the cycloolefin-based resin is substantially a mixture of an organic solvent that does not substantially change the cycloolefin-based resin by contact with an organic solvent that changes the cycloolefin-based resin by contact. A method of manufacturing a polarizing plate comprising contacting the mixed organic solvent containing no solute and the first protective film so that the haze value does not exceed 0.5%, and then bonding the polarizing film through the adhesive. As a method of manufacturing a polarizing plate by bonding a protective film containing a cycloolefin resin to a polarizing film having a dichroic dye adsorbed on a polyvinyl alcohol-based resin through an adhesive agent,
The protective film comprising the cycloolefin-based resin is contacted with an organic solvent containing an alicyclic hydrocarbon and substantially free of solutes such that the haze value of the protective film does not exceed 0.5%, and then the The manufacturing method of the polarizing plate containing bonding to a polarizing film. A first protective film containing a cycloolefin resin on one side of the polarizing film where dichroic dye is adsorbed and oriented to the polyvinyl alcohol resin, and a second protective film containing thermoplastic resin on the other side of the polarizing film, respectively. As a method of manufacturing a polarizing plate by bonding through an adhesive,
The first protective film containing the cycloolefin-based resin is contacted with an organic solvent containing an alicyclic hydrocarbon and substantially free of solutes such that the haze value of the first protective film does not exceed 0.5%. The manufacturing method of the polarizing plate containing bonding to the said polarizing film through an adhesive agent. The process according to claim 3 or 4, wherein the alicyclic hydrocarbon is represented by the following formula (I):

(I)
(Wherein m is an integer of 2 to 6 and R is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.) The method according to any one of claims 3 to 5, wherein the organic solvent is a mixed solvent further comprising an organic solvent which does not substantially change the cycloolefin resin by contact in addition to the alicyclic hydrocarbon. The production method according to claim 6, wherein the organic solvent which does not substantially change the cycloolefin resin is an alkyl ester of an organic acid. 8. The process according to claim 7, wherein the alkyl ester of the organic acid is acetic acid ester. The process according to claim 8, wherein the acetic acid ester is ethyl acetate, isopropyl acetate or propyl acetate. The protective film containing the cycloolefin resin has an in-plane retardation value of 30 nm or more before contact by the organic solvent, and the in-plane retardation of the protective film after the contact. And the contact is made so that the value does not fall more than 3 nm below the in-plane retardation value before the contact. The manufacturing method of any one of Claims 1-10 which simultaneously performs the operation of drying the organic solvent when contacting the protective film containing the said cycloolefin resin with the said organic solvent. The manufacturing method according to any one of claims 1 to 11, wherein the adhesive is an aqueous adhesive. The method according to claim 12, wherein the adhesive contains a polyvinyl alcohol-based resin.