KR20100109433A - Process for producing a polarizing film - Google Patents

Abstract

PURPOSE: A polarizing film manufacturing method is provided to restrain the occurrence of the wrinkle or the abnormal material defect on a film. CONSTITUTION: A polyvinyl alcohol film is processed in the sequence of swelling, dyeing, boric, acid treatment, and cleansing. One axial extension is implemented before or during the process in the polyvinyl alcohol film. The residual rate of boron compound content in the film before and after the cleaning is set at 0.7 to 0.98.

Description

Manufacturing method of polarizing film {PROCESS FOR PRODUCING A POLARIZING FILM}

This invention relates to the manufacturing method of the polarizing film excellent in the external appearance.

As a polarizing film, the thing which carried out the adsorption orientation of the dichroic dye in the polyvinyl alcohol-type film is used conventionally. That is, the iodine type polarizing film which uses iodine as a dichroic dye, the dye type polarizing film which uses a dichroic dye as a dichroic dye, etc. are known. These polarizing films are usually a polarizing plate by bonding protective films, such as triacetyl cellulose, on at least one surface, preferably both surfaces, with an adhesive made of an aqueous solution of polyvinyl alcohol-based resin or the like.

As a manufacturing method of a polarizing film, a polyvinyl alcohol-type film is dyed with the said dichroic dye using a nip roll and a guide roll, it is extended | stretched, and then a polyvinyl alcohol-type film is boric-treated to fix iodine to a film, The method of drying after wash | cleaning processes, such as water washing and the like, is known.

However, in the said manufacturing method, in the said washing process, wrinkles generate | occur | produce in a film, or the boric acid compound resulting from a boric acid process precipitates on a film surface, and a foreign material defect arises, and a color unevenness, a foreign material defect, and a scar are obtained in the obtained polarizing film. (I) occurs and there is a problem that the appearance is lowered.

For example, in JP-3979688-B2, it is described as making the boron atom content in a film into a predetermined value as a manufacturing method of the polarizing film excellent in optical performance and dimensional stability. According to this document, it is described that the boron atom content in a polarizing film can be adjusted by the water washing process.

However, JP-3979688-B2 does not have a specific description of the boron compound content in the film before and after the washing treatment, and even if the method described in JP-3979688-B2 is used, the occurrence of wrinkles and foreign matter defects is sufficiently satisfied. It is a phenomenon that cannot be suppressed.

On the other hand, in P2003-240947-A and JPH08-327823-A, it is described as making into the predetermined value the film width before and behind boric acid treatment as a manufacturing method of the polarizer with high polarization degree. In addition, JPH08-327823-A describes a method for producing a polarizing film having excellent durability, which is uniaxially stretched during treatment with a boron compound, and sets the film width before and after the stretching to a predetermined value.

However, in P2003-240947-A and JPH08-327823-A, there is no specific description of the film width before and after a washing process, and it uses the method described in these P2003-240947-A and JPH08-327823-A. Moreover, it is a phenomenon that it cannot necessarily fully suppress generation | occurrence | production of a wrinkle and a foreign material defect, and development of the manufacturing method of the polarizing film which is more excellent in external appearance is calculated | required.

The subject of this invention is providing the manufacturing method of the polarizing film which has the outstanding external appearance.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve the said subject, the present inventor discovered the solution which consists of the following structures, and came to complete this invention.

(1) A method of producing a polarizing film in which a polyvinyl alcohol-based film is treated in the order of swelling treatment, dyeing treatment, boric acid treatment, and washing treatment, and uniaxially stretched before and / or during these treatments. When the boron compound content in the film of Y is Y and the boron compound content in the film after the washing treatment is X, the residual ratio (X / Y) of the boron compound content in the film before and after one washing treatment is 0.7 to 0.98. The manufacturing method of the polarizing film containing what is set as.

(2) The manufacturing method of the polarizing film as described in (1) which performs the said washing process twice or more.

(3) When the boron compound content in the film before the first washing treatment is Yp, and the boron compound content in the film after the last washing treatment is Xp, the residual boron compound content in the film before and after all the washing treatment. The manufacturing method of the polarizing film as described in (2) whose ratio (Xp / Yp) is 0.7-0.98.

(4) A method for producing a polarizing film in which a polyvinyl alcohol-based film is treated in the order of swelling treatment, dyeing treatment, boric acid treatment, and washing treatment, and uniaxially stretched before and / or during these treatments. When making the film width of A and the film width after washing process into B, the manufacturing method of the polarizing film containing A / B in before and after one washing process to be 0.97-1.03.

(5) The manufacturing method of the polarizing film as described in (4) which performs a washing process twice or more.

(6) The polarization described in (5) in which Ap / Bp before and after all cleaning treatments is 0.97 to 1.03 when the film width before initial cleaning treatment is Ap and the film width after treatment is Bp. Method for producing a film.

(7) When the boron compound content in the film before the washing treatment is Y and the boron compound content in the film after the washing treatment is X, the residual ratio (X) of the boron compound content in the film before and after one washing treatment is determined. / Y) manufacturing method of polarizing film as described in (4) or (5) which makes 0.7-0.98.

(8) Before and after all the washing treatments, the washing treatment is performed two or more times, when the boron compound content in the film before the first washing treatment is Yp and the boron compound content in the film after the last washing treatment is Xp. The manufacturing method of the polarizing film as described in (7) which makes residual rate (Xp / Yp) of boron compound content in the film in 0.7-0.98.

(9) The manufacturing method of the polarizing film in any one of said (1)-(8) whose washing | cleaning temperature in a washing process is 30 degrees C or less.

(10) The manufacturing method of the polarizing plate which bonds a protective film to at least one surface of the polarizing film obtained by the method in any one of (1)-(9).

According to the present invention, since the occurrence of wrinkles and foreign matter defects in the film can be suppressed in the washing treatment, there is an effect that a polarizing film having an excellent appearance without color unevenness, foreign matter defects, scratches, or the like can be obtained. .

<Method for Manufacturing Polarizing Film>

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of the manufacturing method of the polarizing film which concerns on this invention is described. As for the polyvinyl alcohol-type resin which forms the polyvinyl alcohol-type film in this embodiment, what saponified polyvinyl acetate type resin is illustrated normally. As saponification degree, it is about 85 mol% or more, Preferably it is about 90 mol% or more, More preferably, it is about 99-100 mol%. As polyvinyl acetate type resin, the copolymer of vinyl acetate and the other monomer copolymerizable with this besides the polyvinyl acetate which is a homopolymer of vinyl acetate, for example, an ethylene-vinyl acetate copolymer, etc. are mentioned. As another monomer copolymerizable, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, etc. are mentioned, for example. As polymerization degree of polyvinyl alcohol-type resin, it is about 1000-10000, Preferably it is about 1500-5000 degree.

These polyvinyl alcohol-based resins may be modified. For example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral and the like modified with aldehydes can also be used. Usually, as a starting material of polarizing film manufacture, the unstretched film of the polyvinyl alcohol-type resin film whose thickness is about 20 micrometers-100 micrometers, Preferably about 30 micrometers-80 micrometers is used. Industrially, the width of a film is practically about 1500 mm-4000 mm.

This unstretched film is processed in the order of swelling treatment, dyeing treatment, boric acid treatment, washing treatment, and finally, together with the drying treatment, before and / or during treatment of the swelling treatment, dyeing treatment, boric acid treatment, and washing treatment. The thickness of the polyvinyl alcohol polarizing film obtained by performing axial stretching is about 5 micrometers-about 50 micrometers, for example.

The polarizing film of this embodiment is a polyvinyl alcohol-type uniaxially stretched film which adsorbed and oriented a dichroic dye, and the manufacturing method is largely divided, and there are two manufacturing methods. One is a method of uniaxially stretching a polyvinyl alcohol-based film in air or an inert gas, followed by solution treatment in the order of swelling treatment, dyeing treatment, boric acid treatment and washing treatment, and finally drying. The other is a solution treatment of the unstretched polyvinyl alcohol-based film with an aqueous solution in the order of swelling treatment, dyeing treatment, boric acid treatment and washing treatment, and uniaxially stretching in a wet manner in the boric acid treatment and / or the preceding treatment. It is a method of drying.

In all the methods, uniaxial stretching may be performed by one process or may be performed by two or more processes, but it is preferable to perform by a plurality of processes. As a stretching method, a well-known method can be employ | adopted, For example, the inter-roll stretching which extends | stretches by changing a circumferential speed between two nip rolls conveying a film, the hot roll stretching method as described in JP2731813-B2, a tenter stretching method, etc. Can be mentioned. In addition, although the procedure of a process is basically as mentioned above, there is no restriction | limiting in the number of a process bath, a process condition, etc.

It goes without saying that it is also free to insert a process not described in the above process for other purposes. As an example of such a treatment, after boric acid treatment, immersion treatment with an aqueous solution of iodide that does not contain boric acid (iodide treatment), or immersion treatment with an aqueous solution containing zinc chloride or the like that does not contain boric acid (zinc treatment), or the like may be used. Can be mentioned.

The swelling treatment is performed for the purpose of removing foreign substances on the surface of the film, removing the plasticizer in the film, imparting ease of dyeing in the next treatment, plasticizing the film, and the like. The treatment conditions can be determined within a range in which these objects can be achieved, and in a range that does not cause problems such as extreme dissolution of the base film, loss of devitrification, and the like. When swelling the film previously stretched in gas, for example, the film is immersed in an aqueous solution of about 20 ° C to 70 ° C, preferably about 30 ° C to 60 ° C. The immersion time of the film is about 30 seconds to 300 seconds, preferably about 60 seconds to 240 seconds. When swelling an unstretched raw film from the beginning, the film is immersed in an aqueous solution of, for example, about 10 ° C to 50 ° C, preferably about 20 ° C to 40 ° C. Immersion time of a film is about 30 second-300 second, Preferably it is about 60 second-240 second.

In the swelling process, problems such as swelling of the film in the width direction and wrinkles easily occur in the film, so that a wide roll (expander roll), spiral roll, crown roll, cloth guider, bend It is preferable to convey a film, removing wrinkles of a film with well-known wide apparatuses, such as a bar and a tenter clip. In addition, for the purpose of stabilizing the conveyance of the film in the bath, the water flow in the swelling bath is controlled by an underwater shower, an EPC device (Edge Position Control device: a device that detects the end of the film and prevents meandering of the film), and the like. It is also useful to use together. In this process, since a film swells and expands also in the running direction of a film, in order to remove the looseness of the film of a conveyance direction, it is preferable to take means, such as controlling the speed of the conveyance roll before and behind a processing tank. In addition to water (pure), boric acid (described in JPH10-153709-A), chloride (described in JPH06-281816-A), inorganic acid, inorganic salt, water-soluble organic solvent, alcohols, etc. The aqueous solution added in the range of 0.01 to 10 weight% can also be used. Also in a swelling process, you may extend | stretch a film similarly to the dyeing process mentioned later.

The dyeing treatment by the dichroic dye is performed for the purpose of adsorbing and orienting the dichroic dye to the film. As processing conditions, it can determine in the range which can achieve these objectives, and also in the range which does not produce the problem of extreme dissolution, devitrification, etc. of a base film. When iodine is used as the dichroic dye, for example, at a temperature of about 10 ° C. to 45 ° C., preferably about 20 ° C. to 35 ° C., and in a weight ratio, iodide / potassium iodide / water = about 0.003 to 0.2 / about 0.1 to 10 Immersion treatment is performed at / 100 for about 30 seconds to 600 seconds, preferably about 60 seconds to 300 seconds. Instead of potassium iodide, other iodides such as zinc iodide may be used. In addition, you may use another iodide together with potassium iodide. In addition, compounds other than iodide, such as boric acid, zinc chloride, cobalt chloride, and the like may coexist. When boric acid is added, it is distinguished from the following boric acid treatment by the point containing iodine. If it contains about 0.003 parts by weight or more of iodine based on 100 parts by weight of water, it can be regarded as a dye bath.

In the case of using a water-soluble dichroic dye as the dichroic dye, for example, at a temperature of about 20 ° C to 80 ° C, preferably about 30 ° C to 70 ° C, and by weight ratio, dichroic dye / water = about 0.001 to 0.1 / 100 About 30 seconds to 600 seconds, preferably about 60 seconds to 300 seconds immersion treatment. The aqueous solution of the dichroic dye to be used may contain dyeing assistant, etc., for example, may contain inorganic salts, such as sodium sulfate, surfactant, etc. Dichroic dye may be individual and two or more types of dichroic dyes may be used simultaneously.

As described above, the film may be stretched in a dye bath. Stretching can be performed by a method such as varying the circumferential speed of the nip rolls before and after the dyeing tank. In addition, similar to the swelling treatment, a wide roll (expander roll), a spiral roll, a crown roll, a cloth guider, a bend bar, or the like may be provided inside the dye bath and / or in the bath entrance and exit.

The boric acid treatment is performed by immersing a polyvinyl alcohol-based film dyed with a dichroic dye in an aqueous solution containing boric acid at a ratio of about 1 to 10 parts by weight with respect to 100 parts by weight of water.

When the dichroic dye is iodine, it is preferable to contain the iodide in a ratio of about 1 to 30 parts by weight. Examples of the iodide include potassium iodide, zinc iodide, and the like. As compounds other than iodide, for example, zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate and the like may coexist.

This boric acid treatment is performed for color adjustment, such as water resistance by crosslinking, prevention of bluishness, and the like. In the case of water resistance by bridge | crosslinking, crosslinking agents, such as glyoxal and glutalaldehyde, can also be used as needed other than boric acid or with boric acid.

In addition, the boric acid treatment for water resistance may be called by names, such as water resistance treatment, a crosslinking treatment, and immobilization treatment. In addition, the boric acid treatment for color adjustment may be referred to by names such as complementary color treatment and redyeing treatment.

This boric acid treatment is performed by appropriately changing the concentration of boric acid and iodide and the temperature of the treatment bath according to the purpose. The boric acid treatment for water resistance and the boric acid treatment for color adjustment are not particularly distinguished, but can be carried out under the following conditions.

When swelling, dyeing and boric acid treatment of the raw film, when boric acid treatment is intended for the water-resistant by crosslinking, about 3 to 10 parts by weight of boric acid and about 1 to about iodide with respect to 100 parts by weight of water A boric acid treatment bath containing 20 parts by weight is used and is usually performed at a temperature of about 50 ° C to 70 ° C, preferably about 55 ° C to 65 ° C. Immersion time is about 30 to 600 second normally, Preferably it is about 60 to 420 second, More preferably, it is about 90 to 300 second. In addition, when dyeing and boric-acid-processing the film extended | stretched previously, the temperature of a boric-acid treatment bath is about 50 degreeC-85 degreeC normally, Preferably it is about 55 degreeC-80 degreeC.

After the boric acid treatment for water resistance, the boric acid treatment for color adjustment may be performed. For example, when the dichroic dye is iodine, for this purpose, a boric acid treatment bath containing about 1 to 5 parts by weight of boric acid and about 3 to 30 parts by weight of iodide is used for 100 parts by weight of water. It performs at the temperature of 45 degreeC-45 degreeC. Immersion time is about 3 to 300 second normally, Preferably it is about 10 to 240 second. The boric acid treatment for color adjustment is usually performed at a low boric acid concentration, a high iodide concentration, and a low temperature as compared to the boric acid treatment for water resistance.

These boric acid treatments may be performed a plurality of times, and are usually performed two to five times. In this case, the aqueous solution composition and temperature of each boric acid treatment tank to be used may be the same within said range, and may differ. The boric acid treatment for water resistance and the boric acid treatment for color adjustment may be performed a plurality of times. Also in a boric acid process, you may extend | stretch a film similarly to a dyeing process. The final integrated draw ratio is about 4.5 to 7 times, preferably about 5 to 6.5 times.

The boric acid treatment is followed by a washing treatment. This washing treatment is carried out by immersing the polyvinyl alcohol-based film treated with boric acid for washing in water and / or adjusting the color tone, for example, by spraying the washing liquid as a shower or by using dipping and spraying in combination. Also in a washing process, you may extend | stretch a film similarly to a dyeing process.

Here, in this embodiment, the residual ratio of the boron compound content in the film before and after one washing process is 0.7-0.98. Thus, by controlling content of the boron compound before and after a washing process to a specific value, generation | occurrence | production of a wrinkle and a foreign material defect in a film in a washing process can be suppressed. On the other hand, when the said residual ratio is less than 0.7, wrinkles will generate | occur | produce easily in a film in a washing process. As this reason, when the said residual ratio is less than 0.7, a boric acid process is likely to be nonuniform, and it is guessed that wrinkles generate | occur | produce in a part of film by a washing process for that reason. Moreover, when the said residual ratio exceeds 0.98, since the boron compound content in a film will become excessive, a foreign material defect will arise easily in a washing process.

The said residual ratio can be computed as follows. That is, first, the boron compound content in the film before and after a washing process is calculated. Specifically, after each film of predetermined amount before and after a washing process is immersed in a hot water of 95 degreeC for 60 minutes, and completely dissolved, each solution is neutralized and titrated, and each solution is neutralized and titrated from the weight and appropriate amount of a film. The boron compound content in a film is computed. Subsequently, each obtained value is applied to the following formula (I) to calculate the remaining ratio.

[Equation I]

Survival rate = X / Y

X: Boron compound content in the film after washing process

Y: Boron compound content in the film before washing process

As boron compound content in the film before a washing process, it is 2.5 to 5 weight%, Preferably it is about 3 to 4.7 weight%, As a boron compound content in the film after a washing process, 2 to 4.5 weight% is preferable. Preferably from 2.5 to 4.3% by weight. The weight percent is a value relative to the film weight before swelling treatment (ie, untreated).

The said residual ratio can be controlled to 0.7-0.98 by adjusting the washing temperature, composition of a washing | cleaning liquid, washing | cleaning time, etc. in one washing process.

In addition, the frequency | count of washing | cleaning is not limited to 1 time, It can select arbitrarily in the range of about 2-4 times.

When the frequency | count of washing | cleaning is performed in multiple times, when the boron compound content in the film before the first washing process is set to Yp, and the boron compound content in the film after the last washing process is set to Xp, the film before and after all the washing processes It is preferable to make the residual ratio of boron compound content in inside into 0.7-0.98.

As washing temperature, it is 30 degrees C or less, Preferably it is 3-30 degreeC. As the washing liquid, in addition to water, for example, an aqueous solution containing boric acid can be employed. It is preferable to contain boric acid in the ratio of about 0.01-0.5 weight part with respect to 100 weight part of water. When boric acid containing aqueous solution is used as a washing | cleaning liquid, it is preferable to make a small amount of iodide coexist in liquid. These illustrated cleaning liquids may be used alone or in combination of two or more thereof.

When water is used as a washing | cleaning liquid, it is preferable to set it as about 1 to 20 second, and, when employ | adopting boric-acid containing aqueous solution, it is preferable to set it as about 5 to 50 second.

In general, the residual ratio tends to be lowered by setting each condition within the above-mentioned range, for example, when the washing temperature is higher, the boric acid is not contained in the washing liquid, or the content is lower, the washing time is longer. . In order to control the residual ratio in the range of 0.7 to 0.98, a cleaning treatment is carried out by setting the cleaning temperature, the composition of the cleaning liquid, the cleaning time and the like at some point (for example, the cleaning temperature of 15 ° C, the cleaning liquid-water, the cleaning time of 10 seconds, etc.). And the residual rate is confirmed. As a result, in the case where the obtained residual ratio is out of this range, the conditions such as the cleaning temperature, the composition of the cleaning liquid, and the cleaning time described above are adjusted in consideration of the tendency of the residual ratio to appropriately adjust the conditions, and the cleaning treatment is performed again. By confirming a ratio and repeating it until it becomes the range of 0.7-0.98, each condition can be adjusted and determined.

The drying treatment after the washing treatment can be performed in a drying furnace at a temperature of about 40 ° C. to 100 ° C. for about 60 seconds to 600 seconds, whereby the polarizing film of the present embodiment can be obtained. In addition, in this embodiment, in each process after an extending | stretching process, it is good to perform tension control so that the tension of a film may become substantially constant, respectively. When extending | stretching is complete | finished by dyeing process, it is preferable to perform tension control by the subsequent boric acid treatment and washing process.

Next, other embodiment of the manufacturing method of the polarizing film which concerns on this invention is described. In this embodiment, when the film width before washing process is A (henceforth film width A), and the film width after washing process is B (henceforth film width B), it washes once A / B in the front and rear is set to 0.97 to 1.03. Thus, also by controlling the film width before and after one washing process to a specific value, it can suppress that wrinkles generate | occur | produce in a film in a washing process. On the other hand, when said (A / B) is smaller than 0.97 or larger than 1.03, since the change of the film width before and after a washing process becomes large, wrinkles will be easy to generate | occur | produce in a film in a washing process.

As film widths (A, B) before and after the washing treatment, desired values can be adopted depending on the width of the raw film, the degree of uniaxial stretching, the width of the polarizing film obtained, and the like. That is, A / B can adopt a desired value in the range of 0.97-1.03.

Said (A / B) can be controlled to 0.97-1.03 according to the washing | cleaning temperature in a washing | cleaning process, the composition of a washing | cleaning liquid, and washing | cleaning time similarly to said one Embodiment.

In general, the higher the cleaning temperature, the lower the content rate, the lower the content rate, the longer the cleaning time, or the like, the (A / B) tends to be lowered. In order to control (A / B) in the range of 0.7 to 0.98, a test temperature is set at a certain point (for example, cleaning temperature 15 ° C, cleaning liquid-water, cleaning time 10 seconds, etc.). A washing process is performed to check the value of (A / B). As a result, when the obtained value is out of this range, it washes again by adjusting each condition suitably in consideration of the tendency which the conditions, such as said washing temperature, composition of a washing | cleaning liquid, washing | cleaning time, have to the value of (A / B). By performing the process, confirming the value of (A / B), and repeating this until it becomes the range of 0.7 to 0.98, each condition can be adjusted and determined.

In addition, the frequency | count of washing | cleaning is not limited to 1 time, It can select arbitrarily in the range of about 2-4 times.

In the case of plural washing times, when the film width before the first cleaning treatment is set to Ap and the film width after the treatment is set to Bp, the Ap / Bp before and after all cleaning treatments is set to 0.97 to 1.03. desirable.

In addition, similarly to the above-mentioned one embodiment, when the boron compound content in the film before the cleaning treatment is Y and the boron compound content in the film after the cleaning treatment is X, the boron in the film before and after one cleaning treatment. It is preferable that the residual ratio (X / Y) of the compound content is 0.7 to 0.98. When the frequency | count of washing | cleaning is performed in multiple times, when the boron compound content in the film before the first washing process is set to Yp, and the boron compound content in the film after the last washing process is set to Xp, the film before and after all the washing processes It is preferable to make the residual ratio of boron compound content in inside into 0.7-0.98. Since the other structure is the same as that of one Embodiment mentioned above, description is abbreviate | omitted.

<Method of manufacturing polarizing plate>

The polarizing plate can be obtained by bonding a protective film to the at least one surface of the polarizing film manufactured as mentioned above with an adhesive agent. As the protective film, for example, a film made of acetyl cellulose resin such as triacetyl cellulose or diacetyl cellulose, a film made of polyester resin such as polyethylene terephthalate or polyethylene naphthalate, polybutylene terephthalate, polycarbonate resin The film which consists of a film, the film which consists of cycloolefin resin, etc. are mentioned. As a commercially available thermoplastic cycloolefin resin, for example, "Topas" (trademark registration) sold by Ticona, Germany, "Aton" (trademark registration) sold by JSR Co., Ltd., "Zeonoa" and "Xeonex" (both trademark registration) sold by Nihon Xeon Co., Ltd., "Apel" (trademark registration) sold by Mitsui Kagaku Co., etc. are mentioned. What formed these cycloolefin resin into a film can be employ | adopted as a protective film. A well-known method, such as a solvent casting method and a melt extrusion method, can be employ | adopted for film forming. The cycloolefin resin film formed into a film is marketed, for example, "S thinner" etc. which are sold by Sekisui Chemical Co., Ltd. are suitable.

As thickness of a protective film, although thin is preferable, when too thin, intensity | strength will fall and workability will be inferior. Moreover, when too thick, problems, such as transparency fall or the curing time required after lamination | stacking arise. Therefore, the suitable thickness of a protective film is about 5 micrometers-about 200 micrometers, for example, Preferably it is about 10 micrometers-150 micrometers, More preferably, it is about 20 micrometers-100 micrometers.

In order to improve the adhesiveness between the adhesive agent and the polarizing film and / or the protective film, the polarizing film and / or the protective film is subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet irradiation, primer coating treatment, saponification treatment, and the like. Also good.

The protective film may be subjected to surface treatment such as anti-glare treatment, anti-reflection treatment, hard coat treatment, antistatic treatment, antifouling treatment or the like alone or in combination. In addition, the protective film and / or protective film surface protective layer may have ultraviolet absorbers, such as a benzophenone type compound and a benzotriazole type compound, and plasticizers, such as a phenyl phosphate type compound and a phthalate ester compound. Such a protective film may be bonded to one side of a polarizing film, and may be bonded to both surfaces.

A polarizing film and a protective film are laminated | stacked using adhesive agents, such as an aqueous solvent adhesive, an organic solvent adhesive, a hot melt adhesive, and a solvent-free adhesive. Examples of the aqueous solvent adhesive include polyvinyl alcohol-based resin aqueous solution and aqueous two-component urethane emulsion adhesive. Examples of the organic solvent adhesive include two-component urethane adhesive, and the like. And urethane adhesives. When using the acetyl cellulose type film hydrophilized by the saponification process etc. as an adhesive surface with a polarizing film as a protective film, the polyvinyl alcohol-type resin aqueous solution is used suitably as an adhesive agent. In the polyvinyl alcohol-based resin used as an adhesive, in addition to the vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate, a vinyl alcohol system obtained by saponifying a copolymer of vinyl acetate with another monomer copolymerizable with it. The copolymer, Furthermore, the modified polyvinyl alcohol-type polymer etc. which modified these hydroxyl groups partially are mentioned. You may use a polyhydric aldehyde, a water-soluble epoxy compound, a melamine type compound, etc. as an additive for this adhesive agent.

The method of bonding a polarizing film and a protective film is not specifically limited, For example, the method of apply | coating an adhesive uniformly to the surface of a polarizing film or a protective film, laminating | stacking another film on an application surface, and bonding by a roll etc. is mentioned. Can be.

The adhesive agent is applied at a temperature of about 15 ° C to 40 ° C after preparation, and the bonding temperature is usually in a range of about 15 ° C to 30 ° C. After the bonding, a drying treatment is performed to remove a solvent such as water contained in the adhesive. The drying temperature at this time is usually in the range of about 30 ° C to 85 ° C, preferably about 40 ° C to 80 ° C. Thereafter, in the temperature environment of about 15 ° C. to 85 ° C., preferably about 20 ° C. to 50 ° C., and more preferably about 35 ° C. to 45 ° C., the curing process is usually performed for about 1 day to 90 days. good. Since the productivity will worsen when this curing period is long, the curing period is about 1 to 30 days, Preferably it is about 1 to 7 days.

In this way, the polarizing plate by which the protective film was bonded to one side or both sides of a polarizing film can be obtained through an adhesive bond layer.

In the present invention, the protective film may have optical functions such as a function as a retardation film, a function as a brightness enhancement film, a function as a reflective film, a function as a semi-transmissive reflective film, a function as a diffusion film, a function as an optical compensation film, and the like. have. In this case, for example, by laminating an optical functional film such as a retardation film, a brightness enhancement film, a reflection film, a semi-transmissive reflection film, a diffusion film, an optical compensation film, and the like on the surface of the protective film, Such a function can also be provided to the protective film itself. Moreover, you may make a protective film itself a some function like the diffusion film etc. which have a function of a brightness improving film.

For example, a function as a retardation film can be given to the said protective film by performing the extending | stretching process described in JP2841377-B2, JP3094113-B2, etc., or performing the process described in JP3168850-B2. In addition, by forming a fine hole in the above-described protective film by a method as described in JP2002-169025-A or JP2003-29030-A, and also by superimposing two or more layers of cholesteric liquid crystal layers having different center wavelengths of selective reflection. The function as a brightness improving film can be provided. By forming a metal thin film on said protective film by vapor deposition, sputtering, etc., the function as a reflective film or a semi-transmissive reflective film can be provided. By coating the resin solution containing microparticles | fine-particles on the said protective film, the function as a diffusion film can be provided. Moreover, the function as an optical compensation film can be provided by coating and orienting liquid crystal compounds, such as a discotic liquid crystalline compound, to the said protective film. Moreover, using suitable adhesives, brand name: brightness improvement film, such as DBEF [manufactured by 3M Co., Ltd.], viewing angle improvement films, such as brand name WV film (manufactured by Fuji Photo Film Co., Ltd.), brand name: Sumikalite (registered trademark) [ Commercially available optical functional films, such as retardation film, such as Sumitomo Chemical Co., Ltd.], may be directly bonded to a polarizing film.

Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. In addition, the measuring method and evaluation method of each physical property are as follows.

(Remaining rate of boron compound content)

First, the boron compound content in the film before and after one washing process was calculated. That is, 0.2 g of each film before and after the washing treatment was completely immersed in 100 ml of 95 ° C. hot water for 60 minutes and completely dissolved, and then neutralized and titrated in each solution. The boron compound content in each film was determined from the weight and the appropriate amount of the film. Calculated. Next, each obtained value was applied to the said Formula (I), and the residual ratio of the boron compound content in the film before and behind washing | cleaning was computed.

(Occurrence of wrinkles, foreign matter defects)

The film was observed by visual observation.

Example 1

A polyvinyl alcohol film (Kurarevinylone VF-PS # 7500, polymerization degree 2,400, saponification degree 99.9 mol% or more) of 450 mm in width and 75 micrometers in thickness was kept at 30 degreeC pure water, and the tension state was not kept loose. The film was swelled sufficiently by soaking for approximately 100 seconds.

Next, uniaxial stretching was performed while iodine / potassium iodide / water was immersed in an aqueous solution of 0.02 / 1.5 / 100 by weight ratio. Thereafter, while potassium iodide / boric acid / water is immersed in a 55 ° C. aqueous solution having a weight ratio of 12 / 4.4 / 100 and boric acid treatment (water-resistant treatment), until the accumulated draw ratio from the master becomes 5.5 times. After performing axial stretching, the potassium iodide / boric acid / water was immersed in 40 degreeC aqueous solution which is 9 / 2.9 / 100 by weight ratio.

Subsequently, it was immersed and washed for 8 seconds with pure water at 5 ° C. It dried for 3 minutes at 70 degreeC after this washing process, and obtained the polarizing film of 28 micrometers in thickness. At this time, the boron compound content in the film before the washing treatment was 4.25 wt%, and the boron compound content in the film after the washing treatment was 4.17 wt%. And the residual ratio of the boron compound content in the film before and after this washing | cleaning was 0.98, and generation | occurrence | production of a wrinkle was not seen in the film in a washing process. Moreover, the generation | occurrence | production of a foreign material defect was not seen, and the obtained polarizing film had the outstanding external appearance without a color unevenness, a foreign material defect, a scar, etc .. In addition, the said weight% is a value with respect to the film weight before swelling process (that is, untreated).

[Example 2]

Two washing tanks were installed and immersed and washed for 8 seconds in a 15 ° C. solution of potassium iodide / boric acid / water in a weight ratio of 0.3 / 0.15 / 100 by weight in the first washing step and pure water of 15 ° C. in the second washing step for 3 seconds. A polarizing film having a thickness of 28 µm was obtained in the same manner as in Example 1 except for the above.

At this time, the boron compound content in the film before the washing treatment of the first washing step was 4.25 wt%, and the boron compound content in the film after the washing treatment was 4.03 wt%. In addition, the boron compound content in the film before the washing | cleaning process of a 2nd washing | cleaning step was 4.03 weight%, and the boron compound content in the film after this washing process was 3.95 weight%. And the residual ratio of the 1st washing | cleaning step was 0.95, the residual ratio of the 2nd washing | cleaning step was 0.98, and generation | occurrence | production of a wrinkle was not seen in the film in each washing process. Moreover, the generation | occurrence | production of a foreign material defect was not seen, and the obtained polarizing film had the outstanding external appearance without color unevenness, a foreign material defect, a mark, etc ..

Example 3

A polarizing film having a thickness of 28 μm was obtained in the same manner as in Example 1 except that potassium iodide / boric acid / water was immersed and washed for 48 seconds in a 25 ° C. aqueous solution having a weight ratio of 0.6 / 0.3 / 100. At this time, the boron compound content in the film before the washing treatment was 4.25 wt%, and the boron compound content in the film after the washing treatment was 3.40 wt%. And the said residual ratio is 0.80, and generation | occurrence | production of a wrinkle was not seen in the film in a washing process. Moreover, the generation | occurrence | production of a foreign material defect was not seen, and the obtained polarizing film had the outstanding external appearance without color unevenness, a foreign material defect, a mark, etc ..

Comparative Example 1

A polarizing film having a thickness of 29 μm was obtained in the same manner as in Example 1, except that the product was immersed and washed for 48 seconds in 35 ° C. pure water. At this time, the boron compound content in the film before the washing treatment was 4.25 wt%, and the boron compound content in the film after the washing treatment was 2.76 wt%. And the said residual ratio is 0.65 and the wrinkle generate | occur | produced in the film in the washing process.

Comparative Example 2

A polarizing film having a thickness of 28 µm was obtained in the same manner as in Example 1, except that the substrate was immersed and cleaned in pure water at 2 ° C. for 1 second. At this time, the boron compound content in the film before the washing treatment was 4.25 wt%, and the boron compound content in the film after the washing treatment was 4.22 wt%. In addition, although the said residual ratio was 0.99, although the generation | occurrence | production of a wrinkle was not seen in the film in the washing | cleaning process, boric acid began to precipitate in a roll in a short time, and the foreign material defect generate | occur | produced in the film.

Table 1 shows the evaluation results of Examples 1 to 3, Comparative Example 1, and Comparative Example 2.

Example 4

A polyvinyl alcohol film (Kurarevinylone VF-PS # 7500, polymerization degree 2,400, saponification degree 99.9 mol% or more) of 450 mm in width and 75 micrometers in thickness was kept at 30 degreeC pure water, and the tension state was not kept loose. The film was swelled sufficiently by soaking for approximately 100 seconds.

Next, uniaxial stretching was performed while iodine / potassium iodide / water was immersed in an aqueous solution of 0.02 / 1.5 / 100 by weight ratio. Subsequently, uniaxial stretching was performed until the integrated draw ratio from the master was 5.5 times while potassium iodide / boric acid / water was immersed in a 55 ° C. aqueous solution having a weight ratio of 12 / 4.4 / 100 and subjected to boric acid treatment (water-resistant treatment). Thereafter, potassium iodide / boric acid / water was immersed in a 40 ° C. aqueous solution having a weight ratio of 9 / 2.9 / 100.

Subsequently, it was immersed and washed for 8 seconds with pure water at 5 ° C. It dried for 3 minutes at 70 degreeC after this washing process, and obtained the polarizing film of 28 micrometers in thickness. At this time, the boron compound content in the film before the washing treatment was 4.25% by weight, the boron compound content in the film after the washing treatment was 4.17% by weight, and the residual ratio of the boron compound content in the film before and after washing was 0.98. It was. In addition, the film width A before washing | cleaning is 270 mm and the film width B after washing | cleaning is 271 mm (A / B = 1.00), and generation | occurrence | production of a wrinkle is not seen in a film in a washing process, and the obtained polarizing film has a color unevenness and a foreign material defect It had an excellent appearance without scratches or scratches.

Example 5

Two washing tanks were installed and immersed and washed for 8 seconds with a 15 ° C aqueous solution in which potassium iodide / boric acid / water were 0.3 / 0.15 / 100 by weight in the first washing step and pure water at 15 ° C in the second washing step. A polarizing film having a thickness of 28 µm was obtained in the same manner as in Example 4 except for the above.

At this time, the boron compound content in the film before the washing treatment of the first washing step was 4.25 wt%, and the boron compound content in the film after the washing treatment was 4.03 wt%. In addition, the boron compound content in the film before the washing | cleaning process of a 2nd washing | cleaning step was 4.03 weight%, and the boron compound content in the film after this washing process was 3.95 weight%. The remaining ratio of the first washing step was 0.95, and the remaining rate of the second washing step was 0.98.

In addition, the film width A before washing in the first washing step is 270 mm, the film width B after washing is 273 mm (A / B = 0.99), and the film width A before washing in the second washing step is 273 mm, and the film width after washing B was 278 mm (A / B = 0.98), and generation | occurrence | production of a wrinkle was not seen in each washing | cleaning process, and the obtained polarizing film had the outstanding external appearance without a color unevenness, a foreign material defect, or a scar.

Example 6

A polarizing film having a thickness of 28 μm was obtained in the same manner as in Example 4, except that potassium iodide / boric acid / water was immersed and washed for 48 seconds in a 25 ° C. aqueous solution having a weight ratio of 0.6 / 0.3 / 100. At this time, the boron compound content in the film before the washing treatment was 4.25 wt%, the boron compound content in the film after the washing treatment was 3.40 wt%, and the residual ratio was 0.80. And the film width A before washing | cleaning is 270 mm, and the film width B after washing | cleaning is 278 mm (A / B = 0.97), and generation | occurrence | production of a wrinkle is not seen in a film in a washing process, and the obtained polarizing film has a color unevenness and a foreign material defect It had an excellent appearance without scratches or scratches.

Comparative Example 3

A polarizing film having a thickness of 29 μm was obtained in the same manner as in Example 4, except that the product was immersed and washed for 48 seconds in 35 ° C. pure water. At this time, the boron compound content in the film before the washing treatment was 4.25 wt%, the boron compound content in the film after the washing treatment was 2.76 wt%, and the residual ratio was 0.65. And the film width A before washing | cleaning was 270 mm, and the film width B after washing | cleaning was 282 mm (A / B = 0.96), and wrinkles generate | occur | produced in the film in a washing process.

[Comparative Example 4]

After stretching, potassium iodide / boric acid / water was immersed in a 55 ° C. aqueous solution having a weight ratio of 12 / 4.4 / 100, and then immersed and washed for 1 second with pure water at 2 ° C. in the same manner as in Example 4, and the thickness was 30 μm. A polarizing film was obtained. At this time, the boron compound content in the film before the washing treatment was 4.42 wt%, the boron compound content in the film after the washing treatment was 4.37 wt%, and the residual ratio was 0.99. And the film width A before washing | cleaning was 268 mm, and the film width B after washing | cleaning was 258 mm (A / B = 1.04), and wrinkles and a foreign material defect generate | occur | produced in the film in the washing process.

Table 2 shows the evaluation results of Examples 4 to 6, Comparative Example 3, and Comparative Example 4.

Claims (10)

The polyvinyl alcohol-based film is treated in the order of swelling treatment, dyeing treatment, boric acid treatment, and washing treatment,
As a manufacturing method of the polarizing film which uniaxially stretches before and / or during these processes,
When the boron compound content in the film before the cleaning treatment is Y and the boron compound content in the film after the cleaning treatment is X, the residual ratio (X / Y) of the boron compound content in the film before and after one cleaning treatment is determined. The manufacturing method of the polarizing film containing what is set as 0.7-0.98. The manufacturing method of the polarizing film of Claim 1 which performs the said washing process 2 or more times. The boron compound in the film before and after all the washing treatments according to claim 2, wherein when the boron compound content in the film before the first washing treatment is Yp and the boron compound content in the film after the last washing treatment is Xp. The manufacturing method of the polarizing film which makes a residual rate (Xp / Yp) of content into 0.7-0.98. The polyvinyl alcohol-based film is treated in the order of swelling treatment, dyeing treatment, boric acid treatment, and washing treatment,
As a manufacturing method of the polarizing film which uniaxially stretches before and / or during these processes,
The manufacturing method of the polarizing film containing A / B in one washing | cleaning process back and front being 0.97-1.03, when making the film width before washing process into A and the film width after washing process to B. The manufacturing method of the polarizing film of Claim 4 which performs a washing process twice or more. The manufacturing method of the polarizing film of Claim 5 which makes Ap / Bp 0.97-1.03 before and after all the washing processes, when making the film width before an initial washing process Ap and the film width after a process Bp. Way. The boron in the film according to claim 4 or 5, wherein when the boron compound content in the film before the cleaning treatment is Y and the boron compound content in the film after the cleaning treatment is X, the boron in the film before and after one cleaning treatment. The manufacturing method of the polarizing film which makes a residual rate (X / Y) of compound content into 0.7-0.98. The cleaning process according to claim 7, wherein the cleaning treatment is performed two or more times, and when the boron compound content in the film before the first cleaning treatment is Yp and the boron compound content in the film after the last cleaning treatment is Xp, all the cleaning is performed. The manufacturing method of the polarizing film which sets the residual ratio (Xp / Yp) of boron compound content in the film before and behind a process to 0.7-0.98. The manufacturing method of the polarizing film of any one of Claims 1-8 whose washing | cleaning temperature in a washing process is 30 degrees C or less. The manufacturing method of the polarizing plate which bonds a protective film to at least one surface of the polarizing film obtained by the method as described in any one of Claims 1-9.