KR20060041803A - A method for producing a polarizing film, a polarizer and an optical laminate - Google Patents

Abstract

This invention provides the manufacturing method of a polarizing film with less scars and wrinkles, and there is no bending.

In the method of processing a PVA system film and manufacturing a polarizing film, using the wide roll in a process liquid, the maximum wide width (beta) of the wide roll calculated | required by Formula (1) can be calculated | required by Formula (2). It is characterized by arranging a wide roll at a position exceeding the expansion amount γ in the width direction of the film, or using a wide roll having a shape that exceeds.

β = B ₁ × α × r / R

γ = 0.2055 × B ₁ × {exp (-0.0273 × θ ₁ ) -exp) (-0.0273 × θ)}

Where B ₁ is the film width in contact with the roll, α is the contact angle, r is the radius of the roll, R is the radius of curvature of the roll, θ is the running time in the liquid until the film leaves the roll, θ ₁ is the film roll The running time in the liquid until it touches is indicated.

Polarizing film, PVA, wide roll, wide width

Description

A manufacturing method of a polarizing film, a polarizing plate, and an optical laminated body {A METHOD FOR PRODUCING A POLARIZING FILM, A POLARIZER AND AN OPTICAL LAMINATE}

1: is explanatory drawing of the wide roll, (A) is a top view, (B) is sectional drawing.

It is a top view which shows the wide situation of a film.

It is a schematic cross section which shows the example which arrange | positioned the wide roll to the processing tank.

<Explanation of symbols for the main parts of the drawings>

H height

R radius of curvature

r radius

α contact angle

Film width in contact with B ₁ wide roll

Wide film width with B ₂ wide roll

1 guide roll

2 wide rolls

3 wide rolls

4 guide rolls

5 treatment tanks

6 treatment liquid

This invention is a polarizing plate which laminated | stacked the protective film on one or more surfaces of the manufacturing method of a polarizing film which has less a wound | wound and a wrinkle more, and is not broken, the polarizing film obtained, and also a retardation film, a brightness improving film, a viewing angle improvement film, and a semi-transmissive reflective film Either one or a plurality of optical laminates are bonded together.

As a polarizing film, what adsorbed and oriented the dichroic dye to 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. Such a polarizing film is usually a polarizing plate by bonding a protective film such as triacetyl cellulose to one or more surfaces thereof, preferably through an adhesive containing an aqueous solution of polyvinyl alcohol-based resin on both surfaces thereof.

In order to produce a polarizing film using a nip roll and a guide roll, the polyvinyl alcohol-based film was immersed in water to swell, and then dyed with the dichroic dye, stretched, and subsequently to fix the iodine to the film. A method is known in which a polyvinyl alcohol-based film is subjected to boric acid treatment, washed with water, and then dried (see Patent Document 1, for example). At this time, the nip roll before and behind a process bath is given the circumferential speed difference, and a film is stretched, the conveyance direction of a film is changed with a guide roll, and the film is introduce | transduced and extracted in a process liquid.

As the guide roll, a flat rubber roll or a spiral rubber roll whose surface contains a rubber layer is used (see Patent Document 2, for example).

In recent years, along with the high quality of the liquid crystal display device in which a polarizing film is used, there are fewer scratches and wrinkles than the polarizing film obtained by the conventional method, and the polarizing film which does not bend is desired.

<Patent Document 1>

Japanese Patent Laid-Open No. 10-153709

<Patent Document 2>

Japanese Patent Laid-Open No. 2000-147252

The main problem to be solved by the present invention is to provide a method for producing a polarizing film having less scratches or wrinkles and no bending.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to manufacture a polarizing film with few scars and wrinkles, the present inventors used a wide roll as a guide roll, and the film of the largest width | variety amount (beta) which a wide roll has in contact with a wide roll By placing the wide roll at a position exceeding the expansion amount γ in the width direction of the width direction or by using a wide roll having a shape that exceeds the width, the swelling treatment liquid can be made to have fewer wounds and wrinkles, and to avoid bending, in particular, a wide roll made of sponge rubber. When arrange | positioned in the inside, it discovered that the effect of reducing a wound | wrinkle and wrinkles, and being free of bending was large, and came to complete this invention.

That is, in the manufacturing method of the polarizing film of this invention, the polyvinyl alcohol-type film is processed in order of a swelling process, a dyeing process, a boric acid treatment, and a water washing process, and the polarization which carries out uniaxial stretching in a boric acid treatment process and / or the process before it. In the method for producing a film, the maximum width? Of the wide roll obtained by the following formula (1) and the film obtained by the following formula (2) are obtained by using the wide roll as at least one guide roll in the processing liquid. The relationship between the amount of expansion γ in the width direction of the film in contact between (a) is arranged at a position where β> γ is used and / or (b) using a wide roll having a shape of β> γ. It is a manufacturing method of the polarizing film characterized by the above-mentioned.

β = B ₁ × α × r / R

In the formula, B ₁ represents a film width in contact with the wide roll, α represents a contact angle of the wide roll, r represents a radius of the wide roll, and R represents a radius of curvature of the wide roll.

γ = 0.2055 × B ₁ × {exp (-0.0273 × θ ₁ ) -exp (-0.0273 × θ)}

In the formula, B ₁ is as defined above and, θ is the running time of the solution of the film to leave the wide roll, θ ₁ represents the running time of the liquid until the film comes into contact with the wide roll.

The wide roll is a sponge rubber roll, and the hardness of the sponge is 20 to 60 degrees on a JIS Shore C scale, the density is 0.4 to 0.6 g / cm ³ and the surface roughness is 10 to 30S.

Moreover, it is characterized by arrange | positioning the wide roll in a swelling process liquid.

In addition, the polarizing plate of this invention bonds a protective film to one or more surfaces of the polarizing film obtained as mentioned above. This protective film may be equipped with the function of any one of retardation film, a brightness improving film, a viewing angle improvement film, and a semi-transmissive reflective film. Or the optical laminated body which bonded together 1 or more types chosen from the retardation plate, a brightness improving film, a viewing angle improvement film, and a semi-transmissive reflecting plate to the said polarizing plate which bonded the protective film on one or more surfaces.

Best Mode for Carrying Out the Invention

Hereinafter, the present invention will be described in detail.

In the present invention, a polyvinyl alcohol-based resin forming a polyvinyl alcohol (PVA) -based film is usually exemplified by saponifying a polyvinyl acetate-based resin. As saponification degree, it is about 85 mol% or more, Preferably it is about 90 mol% or more, More preferably, it is about 99 mol%-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 which can be copolymerized, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, etc. are mentioned, for example. The degree of polymerization of the polyvinyl alcohol-based resin is about 1000 to 10000, preferably about 1500 to 5000.

Such polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral and the like modified with aldehydes may 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 the film is practically about 1500 mm to 4000 mm.

The thickness of the polyvinyl alcohol polarizing film obtained by processing this unstretched film in order of a swelling process, a dyeing process, a boric acid process, and a water washing process, and finally drying is about 5-50 micrometers, for example.

Although the polarizing film of this invention is the polyvinyl alcohol-type uniaxially stretched film which adsorbed and oriented a dichroic dye, there are two manufacturing methods largely divided as the manufacturing method. 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 water washing treatment, and finally drying. Secondly, the unstretched polyvinyl alcohol-based film is subjected to a solution treatment in the order of swelling treatment, dyeing treatment, boric acid treatment and water washing treatment with an aqueous solution, and uniaxially stretching by wet in the boric acid treatment step and / or the preceding step. It is a method of drying.

In either method, uniaxial stretching may be performed in one step or two or more steps, but it is preferable to perform in a plurality of steps. As a stretching method, a well-known method can be employ | adopted, for example, between the rolls which extend by placing a circumferential speed difference between two nip rolls conveying a film, and the hot roll stretching method as described in patent 2731813, tenter Extending method. In addition, although the order of a process is basically the same as the above, there is no restriction | limiting in the number of process baths, process conditions, etc. In addition, of course, it is also free to insert the process which does not have description in the said process for a separate purpose. As an example of this process, an immersion treatment (iodide treatment) with an aqueous solution of iodide not containing boric acid after boric acid treatment or an immersion treatment (zinc treatment) with an aqueous solution containing zinc chloride or the like which does not contain boric acid may be used. Can be mentioned.

The swelling step is performed for the purpose of removing foreign substances on the surface of the film, removing the plasticizer in the film, imparting reverse dyeing in the next step, plasticizing the film, and the like. The treatment conditions are determined in such a range that such an object can be achieved and in a range in which defects such as extreme dissolution of the base film, loss of transparency, and the like do not occur. 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, more preferably about 60 seconds to 240 seconds. When swelling the 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. The immersion time of the film is about 30 seconds to 300 seconds, more preferably about 60 seconds to 240 seconds.

In the swelling treatment step, problems such as swelling of the film in the width direction and wrinkles in the film are likely to occur, so that a wide roll (expander roll), a spiral roll, a crown roll, a cross guider, a band bar, a tenter clip, and the like will be described later. It is preferable to arrange | position to the specific position to carry out, and to convey a film, taking the wrinkle of a film. It is also useful to control the flow of water in the swelling bath with an underwater shower for the purpose of stabilizing the conveyance of the film in the bath, or to use an EPC device (Edge Position Control device, which detects the end of the film and prevents meandering of the film). Do. In this process, since a film swells and expands also in the traveling direction of a film, in order to remove the looseness of the film of a conveyance direction, it is preferable to take means, for example, to control the speed of the conveyance roll before and behind a processing tank. In addition to the pure water, the swelling treatment bath used may include boric acid (described in Japanese Patent Application Laid-Open No. 10-153709), chloride (described in Japanese Patent Application Laid-Open No. 06-281816), an inorganic acid, an inorganic salt, a water-soluble organic solvent, and alcohols. An aqueous solution added in the range of about 0.01% by weight to 10% by weight can also be used.

The dyeing process by a dichroic dye is performed for the purpose of adsorbing and orienting a dichroic dye to a film. The treatment conditions are determined within the range in which these objects can be achieved, and in the range in which defects such as extreme dissolution of the base film, loss of transparency, and the like do not occur. 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 weight ratio, iodine / KI / water = about 0.003 to 0.2 / about 0.1 to 10 Immersion treatment is performed at a concentration of / 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. Moreover, another iodide can also be used together with potassium iodide. Moreover, compounds other than iodide, for example, boric acid, zinc chloride, cobalt chloride, etc. can also coexist. When boric acid is added, it is distinguished from the following boric acid treatment in that it contains iodine. If it contains about 0.003 weight part or more of iodine with respect to 100 weight part of water, it can be considered as a dyeing tank.

When using a water-soluble dichroic dye as a 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 Immersion treatment is performed at a concentration of about 30 seconds to 600 seconds, preferably about 60 seconds to 300 seconds. The aqueous solution of the dichroic dye to be used may have a dyeing assistant etc., for example, may contain inorganic salts, such as sodium sulfate, surfactant, etc. The dichroic dyes may be used alone or in combination of two or more kinds of dichroic dyes.

As described above, the film may be stretched with a dye bath. Stretching is performed by placing a peripheral speed difference on the nip rolls before and after the dyeing tank. In addition, a wide roll (expander roll), a spiral roll, a crown roll, a cross guider, a band bar, or the like may be provided in the dye bath and / or at the bath entrance as in the swelling step.

The boric acid treatment is performed by immersing a polyvinyl alcohol-based film dyed with a dichroic dye in an aqueous solution containing about 1 to 10 parts by weight of boric acid based on 100 parts by weight of water. When the dichroic dye is iodine, it is preferable to contain about 1 to 30 parts by weight of iodide.

As iodide, potassium iodide, zinc iodide, etc. are mentioned. Moreover, compounds other than iodide, for example, zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate, etc. can also coexist.

This boric acid treatment is performed for water resistance by crosslinking, color adjustment (preventing bluish, etc.). In the case of water resistance by bridge | crosslinking, a crosslinking agent, such as glyoxal and glutaraldehyde, can also be used besides boric acid as needed, or with boric acid.

In addition, the boric acid treatment for water resistance may be called by names, such as a water treatment process, a crosslinking process, and an immobilization process. In addition, the boric acid treatment for color adjustment may be referred to by names such as complementary color treatment, re-dyeing treatment and the like.

This boric acid treatment is performed by suitably changing the concentration of boric acid and iodide, and the temperature of a treatment bath according to the objective.

Boric acid treatment for water resistance and boric acid treatment for color adjustment are not particularly distinguished, but are carried out under the following conditions.

When boric acid treatment is intended for water resistance by crosslinking in the case of swelling, dyeing and boric acid treatment of the raw film, about 3 to 10 parts by weight of boric acid and about 1 to 20 parts by weight of iodide with respect to 100 parts by weight of water The boric acid treatment bath containing 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 usually about 30 to 600 seconds, preferably about 60 to 420 seconds, more preferably about 90 to 300 seconds.

In addition, when dyeing and boric acid treatment of the previously stretched film, the temperature of a boric acid treatment bath is about 50 degreeC-85 degreeC normally, Preferably it is 55 degreeC-80 degreeC.

The boric acid treatment for color adjustment may be performed after the boric acid treatment for water resistance. For example, when the dichroic dye is iodine, 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 for this purpose. It is performed at a temperature of 10 ° C to 45 ° C. Immersion time is usually about 3 to 300 seconds, preferably about 10 to 240 seconds.

Boric acid treatment for color adjustment is usually carried out at low boric acid concentration, high iodide concentration and low temperature as compared to boric acid treatment for water resistance.

These boric acid treatments can be carried out in a plurality of steps, and are usually carried out in a step of 2 to 5 in many cases. In this case, the aqueous solution composition and temperature of each boric acid treatment tank to be used may be the same or different within the said range. The boric acid treatment for water resistance and the boric acid treatment for color adjustment may be performed in a plurality of processes, respectively.

Also in a boric acid treatment process, a film can be extended like a dyeing process. The final integrated draw ratio is about 4.5 to 7.0 times, preferably about 5.0 to 6.5 times.

After the boric acid treatment, it is washed with water. For example, water washing treatment is performed by immersing a polyvinyl alcohol-based film treated with boric acid in water for water resistance and / or color adjustment, spraying water as a shower, or using dipping and spraying in combination. In the water washing treatment, the water temperature is usually about 2 to 40 ° C., and the immersion time is preferably about 2 to 120 seconds. The drying after washing with water is performed in a drying furnace at a temperature of about 40 to 100 ° C. for about 60 to 600 seconds.

In each process after an extending | stretching process, tension control may be performed so that tension of a film may become substantially constant, respectively.

When extending | stretching is complete | finished in a dyeing process, tension control is performed in the subsequent boric acid treatment process and a water washing process process. When extending | stretching is complete | finished by the process before a dyeing process, tension control is performed in the process after the dyeing process and a boric acid process.

When the boric acid treatment step includes a plurality of boric acid treatment steps, the boric acid treatment step following the boric acid treatment step in which the film is stretched and stretched in the first or first to second stages of boric acid treatment step to the water washing step Tension control is performed in each step, or the film is stretched in the first to third boric acid treatment steps, and tension control is performed in each step from the next boric acid treatment step to the washing step of the boric acid treatment step in which the stretching treatment is performed. Although it is preferable to carry out, industrially, the tension control is carried out in each process from the boric acid treatment process following the boric acid treatment process which extended | stretched the said film, and performed the extending | stretching process in the boric acid treatment process from the beginning or the beginning to the 2nd stage. It is more preferable to perform.

In the case of performing the above iodide treatment or zinc treatment after boric acid treatment, tension control is also performed for such a step.

The tension in each process may be the same or different.

In the tension control, the tension to the film is not particularly limited and is appropriately set within the range of about 150 N / m to 2000 N / m, preferably about 600 N / m to 1500 N / m per unit width. . If the tension is less than about 150 N / m, wrinkles or the like tend to be formed on the film. On the other hand, when the tension exceeds about 2000 N / m, problems such as breakage of the film and low life due to wear of the bearing occur. In addition, the tension per unit width is calculated from the film width near the inlet of the step and the tension value of the tension detector.

In addition, when tension control is performed, it may inevitably be slightly stretched and contracted, but in the present invention, this is not included in the stretching treatment.

In the present invention, a wider roll using the wider roll as at least one guide roll in the processing liquid, and the film obtained by the following formula (2) in contact with the wider roll is obtained. The width roll of the shape in which the relationship with the expansion amount (gamma) of the width direction of the film between (a) (beta)> (gamma) is arrange | positioned, and (b) (beta)> (gamma) is used.

<Equation 1>

β = B ₁ × α × r / R

In the formula, B ₁ represents a film width in contact with the wide roll, α represents a contact angle of the wide roll, r represents a radius of the wide roll, and R represents a radius of curvature of the wide roll.

<Equation 2>

γ = 0.2055 × B ₁ × {exp (-0.0273 × θ ₁ ) -exp (-0.0273 × θ)}

In the formula, B ₁ is as defined above and, θ is the running time of the solution of the film to leave the wide roll, θ ₁ represents the running time of the liquid until the film comes into contact with the wide roll.

Explanatory drawing of the wide roll is shown in FIG. (A) is a top view, (B) is sectional drawing.

The wide roll has a substantially arcuate shape, the radius of curvature is indicated by R, and the arc height is indicated by H. The radius of the wide roll is indicated by r, the contact angle of the surface on which the film is in contact with the wide roll is represented by α, and the length of the contacted surface is represented by α · r.

2 is a plan view showing the state of the wide film, the width of the film in contact with the wide roll ₁ B, the wide rolls in a contact portion, a wide width film is represented by B _2.

It is a schematic cross section which shows the example which arrange | positioned the wide roll to the processing tank. A film is conveyed through the wide rolls 2 and 3 arrange | positioned in the process liquid 6 of the guide roll 1, 4, and the processing tank 5 in a machine, and is processed by a process liquid. The film enters the processing liquid at point A, contacts the wide roll 2 at point B, falls off at point C, contacts the wide roll 3 at point D, and is separated from point E and exits from the processing liquid at point F. The travel time θ in the liquid until the film leaves the wide roll with respect to the wide roll 2 is the travel time between A and C, and the travel time θ ₁ in the liquid until the film contacts the wide roll is between A and B. Is the driving time. The travel time θ in the liquid until the film leaves the wide roll with respect to the wide roll 3 is the travel time between A and E, and the travel time θ ₁ in the liquid until the film contacts the wide roll is between A and D. Is the driving time.

β changes depending on the shape and position of the wide roll, and γ changes according to the shape, position of the wide roll and the conveyance speed of the film. The conveyance speed of a film is set in other processing conditions in many cases, and it does not change the conveyance speed in order to make it into (beta)> (gamma). Usually, the width roll of an expected shape is selected and the position to arrange | position is adjusted, and when this is insufficient, this is repeated and the optimal position and / or shape of the width roll which satisfy (beta)> (gamma) is determined.

The wide roll is preferably a wide roll made of sponge rubber (sponge rubber wide roll), and the hardness of the sponge is about 20 to 60 degrees on the JIS Shore C scale measured by the test method of JIS K 6301, preferably about 25 to 40 degrees, density is about 0.4 to 0.6 g / cm ³ , preferably about 0.42 to 0.57 g / cm ³ , and the surface roughness is expressed by the average interval S of the local calculations of the roughness curve of JIS B 0601 (surface roughness) It is preferred that it is about 10-30S, preferably about 15-25S.

It is preferable to use a wide roll especially in a swelling process process, and it is preferable to use a sponge rubber wide roll at that time. In the swelling treatment step, the polyvinyl alcohol-based film swells in both length and width directions by absorbing the bath solution, but wrinkles and breaks occur on the rolls when tension is applied, particularly, without swelling in the width direction. The use of a sponge rubber wide roll can greatly reduce the tension applied to the film due to its light weight, and at the same time, the film holding force is high due to its high surface roughness, so that even a low tension can exhibit sufficient wide force. One function, the meandering prevention function, is also maximized, which reduces wrinkles and eliminates breaks.

The use of the wide roll is not limited to the swelling treatment, and can also be used in other treatments.

A protective film is bonded by an adhesive agent on at least one surface of the polarizing film thus produced, and a polarizing plate is obtained.

As the protective film, for example, a film containing an acetyl cellulose resin such as triacetyl cellulose or diacetyl cellulose, a film containing a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, polybutylene terephthalate, poly The film containing a carbonate resin and the film containing cycloolefin resin 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" (all are trademark registration) sold from Nihon Xeon, and "Apel" (trademark registration) sold from Mitsui Kagaku. A film formed of such a cycloolefin resin is used as a protective film, but a known method such as a solvent casting method or a melt extrusion method is suitably used for the film formation. The cycloolefin resin film formed into a film is also marketed, for example, "Esshina", "SCA40", etc. which are sold from Sekisui Kagaku Kogyo Co., Ltd. are mentioned.

Although it is preferable that the thickness of a protective film is thin, when too thin, intensity | strength will fall and workability will fall, while too thick will cause problems, such as transparency falling or the curing time required after lamination | stacking may become long. Thus, the suitable thickness of the protective film is, for example, about 5 to 200 mu m, preferably about 10 to 150 mu m, more preferably about 20 to 100 mu m.

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 are subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet irradiation, primer coating treatment and saponification treatment. May be performed.

The protective film may be subjected to surface treatment such as anti-glare treatment, anti-reflection treatment, hard coating 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 phthalic acid ester compound.

Such a protective film may be bonded to one side of the polarizing film, or may be bonded to both sides.

A polarizing film and a protective film are laminated | stacked using adhesive agents, such as a water-soluble adhesive, an organic solvent adhesive, a hot melt adhesive, and a solvent-free adhesive. As an aqueous solvent adhesive, For example, polyvinyl alcohol-type resin aqueous solution, an aqueous two-component urethane emulsion adhesive, etc., As an organic solvent adhesive, For example, a two-component urethane adhesive etc., As a solvent-free adhesive, For example, a one-component urethane adhesive etc. Each can be mentioned. When using the acetyl cellulose type film hydrophilized by a 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 polymer of vinyl acetate and other monomers copolymerizable therewith. Copolymers, and modified polyvinyl alcohol polymers in which these hydroxyl groups are partially modified. A polyhydric aldehyde, a water-soluble epoxy compound, a melamine type compound, etc. can also be used for this adhesive agent as an additive.

The method of bonding a polarizing film and a protective film is not specifically limited, For example, an adhesive is apply | coated uniformly to the surface of a polarizing film or a protective film, the film of one side is further laminated | stacked on an application surface, and it bonds by a roll etc. and drys The method etc. are mentioned.

Typically, the adhesive is applied at a temperature of about 15 to 40 ° C. after manufacture, and the bonding temperature is usually in the range of about 15 to 30 ° C. After the bonding, the drying treatment is performed to remove a solvent such as water contained in the adhesive, but the drying temperature at this time is usually in the range of about 30 to 85 ° C, preferably about 40 to 80 ° C. Thereafter, the adhesive may be cured by curing about 1 to 90 days in a temperature environment of about 15 to 85 ° C, preferably about 20 to 50 ° C, more preferably about 35 to 45 ° C. The longer the curing period is, the lower the productivity is. The curing period is about 1 to 30 days, preferably 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 through an adhesive bond layer is obtained.

In the present invention, the protective film may be provided with 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. Further, the protective film itself may be provided with a plurality of functions, such as a diffusion film having a function of the brightness enhancement film.

For example, a function as a retardation film can be given to the said protective film by giving the extending | stretching process of patent 2841377, the patent 3031113, etc., or performing the process of patent 3168850. In addition, by forming a fine hole in the protective film in the same manner as described in Japanese Patent Application Laid-Open No. 2002-169025 or Japanese Patent Application Laid-Open No. 2003-29030, two or more layers of cholesteric in which the central wavelength of selective reflection is also different. By superimposing a liquid crystal layer, 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 above-mentioned protective film with the resin solution containing microparticles | fine-particles, 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, a brand name: brightness improvement films, such as DBEF (made by 3M Corporation), a brand name: viewing angle improvement films, such as a WV film (made by Fuji Shashin Film Co., Ltd.), a brand name: Sumikalite (trademark registration) Commercially available optical functional films, such as retardation film, such as (Sumitomo Chemical Industries, Ltd.), can also be directly bonded to a polarizing film.

Example

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further more concretely, this invention is not limited to these examples.

<Example 1>

A swelling tank, a dyeing tank, a first boric acid treatment tank, a second boric acid treatment tank, as described below, for carrying out a polyvinyl alcohol film having a thickness of 75 µm (Kurarevinylone VF-PS # 7500, polymerization degree 2,400, saponification degree 99.9 mol% or more). , It washed in the order of a washing tank, and manufactured the polarizing film.

As shown in FIG. 3, as two guide rolls in a processing liquid using a swelling tank, the radius r: 37.5 mm, the hardness of the sponge was 25 degrees on the JIS Shore C scale, the density was 0.42 g / cm ³ , and the surface roughness. A sponge rubber wide roll of 20 S was used. Among other groups, a roll made of NBR rubber having a radius of 35 mm, a surface roughness of 0.6 S, and a rubber hardness (JIS Shore A scale) of 80 degrees was used as a guide roll in another treatment liquid.

The first wide roll (2 in Fig. 3) has a radius of curvature R: 1303 mm and the arc height H: 35 mm, and the second wide roll (3 in Fig. 3) has a radius of curvature R: 1813 mm and an arc height H: 25 All were set to mm, and the contact angle (alpha) was arrange | positioned in the position which becomes 1.5 rad.

The conveying speed of the polyvinyl alcohol film is about 0.34 m / min, and the traveling time θ in the liquid until the film leaves the first wide roll at this time is 20 seconds, and the traveling in the liquid until the first wide roll is in contact with the film. The time θ ₁ is 11 seconds, and the running time θ in the liquid until the film leaves the second wide roll is 66 seconds, and the running time θ ₁ in the liquid until it comes in contact with the second wide roll is 57 seconds.

The treatment liquid of the swelling tank was pure water at about 30 ° C., and the polyvinyl alcohol film was conveyed while being kept in a tension state so as not to loosen and sufficiently swollen. Immersion time is about 80 seconds.

At this time, the film width B ₁ in contact with the first wide roll was 369 mm, and the film width B ₁ in contact with the second wide roll was 407 mm.

When the maximum width? Of the wide roll is obtained from Equation 1, the first wide roll is 15.9 mm, the second wide roll is 12.6 mm, and the amount of expansion in the width direction of the film between the films in contact with the respective wide rolls. When gamma is calculated | required from Formula (2), a 1st wide roll is 12.2 mm and a 2nd wide roll is 3.8 mm, and both extension rolls are (beta)> (gamma).

When the running and surface conditions of the film were observed, there was no generation of wrinkles, breaks or scratches, and the stretch running state of the film was very stable.

Next, uniaxial stretching (stretching ratio: 4.0 times) was performed, while iodine / potassium iodide / water was immersed in the aqueous solution of 0.02 / 1.5 / 100 by weight ratio, and dyed. Then, uniaxial stretching was performed until the integrated draw ratio from the master became 5.9 times while potassium iodide / boric acid / water was immersed in an aqueous solution of about 60 ° C. having a weight ratio of 10/5/100 by boric acid treatment. In addition, extending | stretching was performed by having a circumferential speed difference in the nip roll arrange | positioned before and behind a processing tank.

Further, a second boric acid treatment was performed by immersing the potassium iodide / boric acid / water in a weight ratio of 10/3/100 for about 30 seconds at about 40 ° C. After the second boric acid treatment, water washing was performed for 10 seconds with pure water of about 10 ° C. After washing with water, the mixture was dried at 60 ° C. for 2 minutes to obtain an iodine polarizing film having a thickness of about 28 μm.

No wound or wrinkle was seen in the obtained polarizing film.

Polyvinyl alcohol adhesive agent is apply | coated to both surfaces of the obtained polarizing film, and a protective film (triacetylcellulose film which saponified to the surface, "Fuji-Tech (trademark registration) T80 UNL", a Fuji Film Co., Ltd. product, 80 micrometers in thickness) ) Was bonded to both surfaces, and dried at about 60 ° C. for about 5 minutes to obtain a polarizing plate.

A polarizing plate without scratches or wrinkles was obtained.

Comparative Example 1

As the first wide roll, the radius r: 28 mm, the radius of curvature R: 3008 mm, the arc height H: 15 mm, the hardness of the sponge is 25 degrees on the JIS Shore C scale, the density is 0.42 g / cm ³ , and the surface roughness A polarizing film was produced in the same manner as in Example 1 except that the contact angle α was placed at a position at which the contact angle α became 1.1 rad using a 20 S sponge rubber wide roll.

The running time θ in the liquid until the film leaves the first wide roll at this time is 9 seconds, and the running time θ ₁ in the liquid until it contacts the first wide roll is 6 seconds, and the film leaves the second wide roll. The running time θ in the liquid up to is 34 seconds, and the running time θ ₁ in the liquid up to the second wide roll is 30 seconds.

The film width B ₁ in contact with the first wide roll was 360 mm, and the film width B ₁ in contact with the second wide roll was 390 mm.

When the maximum width? Of the wide roll is obtained from Equation 1, the first wide roll is 3.7 mm and the second wide roll is 12.1 mm, and the expansion amount γ in the width direction of the film between the wide rolls is determined. When calculated | required from Formula (2), a 1st wide roll is 4.9 mm and a 2nd wide roll is 3.7 mm, and it is (beta) <(gamma) in a 1st wide roll and (beta)> (gamma) in a 2nd expansion roll.

When the running and surface conditions of the film were observed, wrinkles and breaks of the film were generated from the first wide rolls, and the breaks once generated were not eliminated as the second wide rolls.

Wrinkles and bending were seen in the obtained polarizing film.

Compared with the conventional method, a polarizing film with less scratches and wrinkles and no breakage is obtained.

In particular, by disposing the sponge rubber wide roll and disposing the wide roll in the expansion treatment liquid, the effect of reducing the scratches and wrinkles and eliminating the kink is large.

By using the polarizing plate and optical laminated body of this invention for a liquid crystal display device, a thin and high quality liquid crystal display can be obtained.

Claims (6)

The width direction of the film between the width | variety between the width | variety which the width | variety width (beta) which the width | variety roll obtained by the following formula (1) and the film obtained by the following formula (2) contact | connect a wide roll using a wide roll as one or more guide rolls of a process liquid. A polyvinyl alcohol-based film, characterized in that a wide roll is placed at a position at which the expansion amount γ of (a) becomes β> γ and / or (b) a wide roll having a shape of β> γ is used. The manufacturing method of the polarizing film which carries out uniaxial stretching in the process of a swelling process, a dyeing process, a boric acid process, and a water washing process, and a boric acid process and / or the process before it. <Equation 1> β = B ₁ × α × r / R In the formula, B ₁ represents a film width in contact with the wide roll, α represents a contact angle of the wide roll, r represents a radius of the wide roll, and R represents a radius of curvature of the wide roll. <Equation 2> γ = 0.2055 × B ₁ × {exp (-0.0273 × θ ₁ ) -exp (-0.0273 × θ)} In the formula, B ₁ is as defined above and, θ is the running time of the solution of the film to leave the wide roll, θ ₁ represents the running time of the liquid until the film comes into contact with the wide roll. The polarizing film according to claim 1, wherein the wide roll is a sponge rubber roll, and the sponge has a hardness of 20 to 60 degrees on a JIS Shore C scale, a density of 0.4 to 0.6 g / cm ³ , and a surface roughness of 10 to 30 S. Method of preparation. The manufacturing method of the polarizing film of Claim 1 which arrange | positions a wide roll in a swelling process liquid. The polarizing plate by which the protective film is bonded by one or more surfaces of the polarizing film manufactured by the method of Claims 1-3. The polarizing plate of Claim 4 in which the said protective film is equipped with the function of any one of retardation film, a brightness improving film, a viewing angle improvement film, and a transflective film. The optical laminated body by which the polarizing plate of Claim 4 and 1 or more types chosen from retardation film, a brightness improving film, a viewing angle improvement film, and a semi-transmissive reflective film are bonded together.

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