TW201638170A - Method for manufacturing polyvinyl alcohol polymer film - Google Patents

Abstract

The problem of the present invention is to provide polyvinyl alcohol polymer film which may manufacture polarizing film and even polarizer having few defects with good yield, and to provide film roll which may manufacture polarizing film and even polarizer wherein the difference of the surface property from the start winding part to the stop winding part is little and the quality is stable. The solution of the present invention is a film roll which is made by continuously winding lengthy polyvinyl alcohol polymer film having the number of defect of 0.25/m2 or less, wherein the defect sinks from the surface of the film, and the area is 400 [mu]m2 or more and the depth is 0.3 [mu]m or more. Regarding the defect sinking from the surface of the film, and the area of 400 [mu]m2 or more and the depth of 0.3 [mu]m or more, the number of the defect at the start winding part relative to the number of the defect at the stop winding part is 1.4 times or less.

Description

Method for producing polyvinyl alcohol polymer film

The present invention relates to a polyvinyl alcohol-based polymer film which can be used as a film roll or the like in the production of a polarizing film (hereinafter, "polyvinyl alcohol" may be simply referred to as "PVA"), and the polyvinyl alcohol system may be used. A method for producing a polarizing film of a polymer film, a film roll in which a polarizing film or a PVA polymer film is continuously wound, and a method for producing a PVA polymer film.

The PVA-based polymer film is used in various applications utilizing the unique properties of transparency, optical properties, mechanical strength, water solubility, etc., and in particular, recently, the use of the excellent optical properties has been expanded to constitute a liquid crystal display (LCD). The use of the raw material (film roll) of the polarizing film of the polarizing plate of the basic constituent elements. Although the large screen is rapidly promoted in the field of liquid crystal monitors and liquid crystal televisions, if the polarizing plate is defective, it cannot be incorporated into the product, and the yield (product yield) is lowered. Therefore, the polarizing plate and the polarized light which are more defect-free than the current one are required. film.

However, various optical technologies including a protective film and a retardation film in addition to the polarizing film have been known. For example, heating a thermoplastic resin of polyester, polyamide or polyolefin to above the melting point When a molten polymer is formed and extruded by a nozzle and cooled, when a film used for optical use or the like is produced, an oligomer (oligomer) present in the polymer is deposited on the surface of the film and adhered thereto. The casting drum or the surface of the roll becomes a problem of the surface of the film, and the method known to solve the problem is to use a film manufacturing apparatus which uses a peripheral surface having a surface roughness of 1 S or less and a surface having a surface relative to chromium. A roll or roll for producing a film of a chromium-plated film having a carbon atom number of 0.5 to 5% (see Patent Document 1). Patent Document 1 specifically discloses that polyethylene terephthalate is melted at 275 ° C, extruded through a T die, and rapidly cooled in a casting drum cooled to 25 ° C to form a non-wafer, and then placed in a ratio of casting to casting. When a plurality of metal rolls on the downstream side of the cylinder are heated or cooled, a part of the plurality of metal rolls is a roll having a specific chrome film.

Further, it is known that when a polymer resin solution is cast on a support to form a film by solution film formation, transparency and surface usable for optical use are obtained in order to eliminate the surface defect (the defect that the surface of the film has a convexity floating). In the polymer resin film having excellent flatness, the number of defects per unit area of the specific size of the surface of the support to be used is not more than a specific value (see Patent Document 2). Patent Document 2 specifically describes an aromatic polycarbonate film which is obtained by dissolving an aromatic polycarbonate resin in a mixed solvent of ethanol and dichloromethane and a support having specific surface characteristics (by A mirror-polished plate made of SUS-316 is prepared by adjusting the temperature of any of the above to about 15 ° C, and applying the solution to a support by a hand-made mold and drying it.

Moreover, it is known that the film is melt-extruded by an extruder. When a thermoplastic resin (a polymer containing an alicyclic structure or a cellulose ester) is produced by a melt casting method using a cooling drum to produce an optical film, it is used as a method for releasing the strong adhesion of dirt or foreign matter to the cooling drum. In order to solve the problem of appearance defects such as "crushing", the organic solvent is attached to the surface of the cooling drum, and then the surface of the cooling drum is wiped by a wiping method, and the dirt on the surface of the cooling drum is removed together with the organic solvent, and then wiped. Then, the surface of the rotating drum is cooled, and the film-shaped thermoplastic resin melt-extruded by the extruder is adhered and cooled, whereby an optical film is produced (see Patent Document 3). Patent Document 3 discloses that a mixture containing a hydride of a norbornene-based ring-opening polymer and cellulose acetate propionate is melt-extruded, and a film-form resin melt is adhered to a cooling coil provided with a specific cleaning device. A cylinder (having a surface of a hardened chrome-plated film having a Vickers hardness of 800 or an amorphous chrome-plated surface having a Vickers hardness of 1200) is cooled and solidified to form a resin sheet while being conveyed.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 9-207210

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2000-84960

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2006-82261

[Patent Document 4] Japanese Patent Publication No. 1-19477

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2005-238833

[Patent Document 6] Japanese Patent Laid-Open No. 9-1568

[Patent Document 7] Japanese Patent Laid-Open Publication No. 2001-315138

However, it is difficult to manufacture a polarizing film or a polarizing plate having few defects at a level required in recent years by simply adopting the above-described conventional technique. That is, in Patent Document 1, it is necessary to heat a thermoplastic resin to a melting point or higher to form a molten polymer. However, in addition to a special modified PVA-based polymer, a PVA-based polymer is not a thermoplastic resin, and it is difficult to form such a film. The method is used in the production of a PVA-based polymer film, and for example, a film excellent in surface characteristics cannot be obtained even if it can be used. Further, as a method for producing a PVA-based polymer film, a film-forming stock solution obtained by dissolving a PVA-based polymer in a liquid medium or a film-forming stock solution containing a PVA-based polymer and a liquid medium and melting the PVA-based polymer is known. a method of casting the solution onto a support and drying it to form a film, but the method and the method of cooling the film on a casting drum substantially without a molten polymer containing the liquid medium as described in Patent Document 1. In the case of using the film forming raw material described in Patent Document 1, the above-mentioned film forming stock solution is used, and this is produced by casting on the film manufacturing drum and drying it. When a PVA-based polymer film is formed into a film, the fineness of fine cracks existing on the surface of the chrome-plated film of the film manufacturing drum can not be sufficiently controlled, and the polarized light produced by using the obtained PVA-based polymer film can be used. The plate or polarizing film cannot fully achieve the quality level required in recent years.

On the other hand, Patent Document 2 relates to a film forming method in which a solution containing a polymer resin and a solvent as a main component is cast on a support to be dried and then the solvent is removed, for example, by simply using a patent document. 2 method can eliminate the disadvantage of the surface of the film floating convex Further, the disadvantage of the surface depression of the film cannot be sufficiently controlled, and the polarizing plate or the polarizing film produced by using the obtained PVA-based polymer film cannot sufficiently achieve the quality level required in recent years.

Further, the method of Patent Document 3 is the same as the method of Patent Document 1, and the melt of the thermoplastic resin is cooled by the cooling drum, so that it is difficult to apply the method of Patent Document 3 to the production of the PVA-based polymer film, for example, even if It is also impossible to obtain a film having excellent surface characteristics. In addition, a film forming stock solution obtained by dissolving a PVA-based polymer in a liquid medium or a film forming stock solution containing a PVA-based polymer and a liquid medium and melting the PVA-based polymer is used simply by using the wiping means described in Patent Document 3. This flow is cast on a metal support and dried to form a PVA-based polymer film, and the disadvantage of the concave shape cannot be sufficiently controlled. Instead, the surface of the metal support is contacted with the wiping means in the metal support. The surface is cracked or the like, and the surface properties of the obtained PVA-based polymer film are deteriorated.

In view of the above, an object of the present invention is to provide a PVA-based polymer film which can produce a polarizing film and a polarizing plate having few defects in a good yield. Further, an object of the present invention is to provide a film roll in which an elongated PVA-based polymer film is continuously wound, and to provide a surface property from the winding start portion to the winding end portion of the PVA-based polymer film. A film roll of a polarizing film and a polarizing plate which are small in difference and stable in quality.

Further, the PVA-based polymer film is often in the form of a film roll in which a long PVA-based polymer film is continuously wound, because it is easy to store and transport, and can be used continuously. In the roll, wrinkles are likely to occur on the film due to poor slippage between the films, and the wrinkles are likely to cause deterioration in the quality of the produced polarizing film. On the other hand, in the polarizing film, the above defects are also required to reduce the unevenness of the dyeing. Here, another object of the present invention is to provide a PVA-based polymer film which is less likely to cause wrinkles in a film roll and which can easily produce a polarizing film which reduces uneven dyeing, and a film roll continuously wound therefrom .

In the case of producing a polarizing film using a PVA-based polymer film as a film roll, it is usually subjected to dyeing, uniaxial stretching, and fixing treatment with respect to the PVA-based polymer film, but when uniaxially stretching is performed in a dry manner, In the dyeing step and the fixing treatment step, and in the uniaxial stretching in a wet manner, in addition to the steps, in the swelling step and the uniaxial stretching step before the uniaxial stretching, the treatment bath is used. A part of the PVA-based polymer is eluted in the middle, and the eluted PVA-based polymer precipitates in the treatment bath and adheres to the film or precipitates on the film, and remains as a foreign substance in the obtained polarizing film, and the quality and yield are lowered. Accordingly, an object of the present invention is to provide a method for producing a polarizing film for producing a polarizing film having such a small amount of foreign matter, and a polarizing film having a small amount of foreign matter produced thereby.

Furthermore, an object of the present invention is to provide a method for producing a PVA-based polymer film which is capable of easily producing the above PVA-based polymer film and film roll.

The inventors of the present invention have concentrated on the results of repeated review in order to achieve the above object, and have found that the PVA system in a solution state or a molten state is polymerized. When the slurry is cast on the surface of the metal support of the drum or the belt and dried to produce a PVA-based polymer film, a small portion of the numerous cracks present on the surface of the metal support adheres to the resin deposit. The foreign matter is transferred to the film or the like in a convex shape, and the PVA-based polymer film having a large number of defects in the surface of the film, and the PVA-based polymer film thus produced are a polarizing film and a polarizing plate. The number of defects is increased, and the quality level required in recent years cannot be sufficiently achieved, or the yield of the polarizing film and the polarizing plate is lowered.

Further, when a metal support having a chrome-plated surface and a surface hardness in a specific range is used, a general treatment performed on the surface of the metal support before the start of film formation such as buffing or the like can be easily reduced. The number of cracks on the surface of the metal support can be reduced as compared with the conventional one, and the number of defects of the surface of the obtained PVA-based polymer film can be reduced. When such a PVA-based polymer film is used as a film roll for producing a polarizing film, it is found A polarizing film and a polarizing plate which have few defects and can satisfy the quality grade required in recent years are produced in good yield.

In addition, in addition to the above knowledge, it has been found that when a metal support having a chrome-plated surface and a surface hardness in a specific range is used, the PVA-based polymer film can be dented by the surface of the film even if it is continuously formed over a long period of time. The fluctuation is maintained at a lower level than usual. For example, when a film roll in which an elongated PVA-based polymer film is continuously wound is produced, the winding portion from the PVA-based polymer film to the winding end portion can be obtained. The difference in surface characteristics is small, and a film roll of a polarizing film and a polarizing plate which can produce a stable quality can be easily obtained.

Moreover, the surface of the use has a chrome layer and the surface hardness is In the case of the metal support of a specific range, it has been found that a PVA-based polymer film having a surface characteristic of both surfaces of the film in a specific range can be easily obtained, and the PVA-based polymer film is hardly wrinkled in the film roll continuously wound to suppress polarization. The film quality is lowered, and a polarizing film having a reduced dyeing unevenness can be easily obtained according to the PVA-based polymer film, and when a polarizing film is produced by a specific method using the PVA-based polymer film, foreign matter can be easily obtained. Polarized film.

The present inventors have further reviewed the present invention based on such knowledge, and have completed the present invention.

That is, the present invention relates to the following:

[1] A PVA-based polymer film having a defect area of 400 μm ² or more and a depth of 0.3 μm or more on the surface of the film is 0.25/m ² or less (hereinafter, the PVA-based polymer film is also used). It is called "PVA-based polymer film (1)");

[2] The PVA-based polymer film according to [1] above, wherein the number of the above disadvantages is 0.15 / m ² or less;

[3] The PVA-based polymer film according to the above [1] or [2], wherein a degree of polymerization of the PVA-based polymer contained in the PVA-based polymer film is 3,000 or more and 10,000 or less;

[4] The PVA-based polymer film according to any one of [1] to [3] above, which is a long-shaped polyvinyl alcohol-based polymer film;

[5] The PVA-based polymer film according to [4] above, which has a length of 6,000 m or more;

[6] The PVA-based polymer film according to [4] or [5] above, wherein the above disadvantages are contained in the longitudinal direction of the film at substantially constant intervals. a disadvantage of the same position in the width direction of the film;

[7] A film roll in which a long PVA-based polymer film is continuously wound, and has a disadvantage that the recessed area of the film surface is 400 μm ² or more and the depth is 0.3 μm or more, relative to the PVA-based polymer film. The number of defects in the winding start portion is 1.4 times or less in the winding end portion of the PVA-based polymer film (hereinafter, the film roll is also referred to as "film roll (1)");

[8] The film roll of the above [7], wherein the number of the above disadvantages is 0.25 / m ² or less;

[9] The film roll of the above [7], wherein the number of the above disadvantages is 0.15 / m ² or less;

[10] The film roll of any one of [7] to [9], wherein a degree of polymerization of the PVA-based polymer contained in the PVA-based polymer film is 3,000 or more and 10,000 or less;

[11] The film roll of any one of the above [7] to [10] wherein the polyvinyl alcohol polymer film has a length of 6,000 m or more;

[12] The film roll according to any one of [7] to [11] wherein the above disadvantages include the disadvantage that substantially the same position in the width direction of the film is present at substantially constant intervals in the longitudinal direction of the film;

[13] A PVA-based polymer film in which the root mean square roughness is measured on both sides of the film, and the difference in root mean square roughness between the two groups is 0.3 nm or more and 10 nm or less, and the root mean square roughness is small. The degree is 10 nm or less (hereinafter, the PVA-based polymer film is also referred to as "PVA-based polymer film (2)");

[14] A PVA-based polymer film according to [13] above, wherein a larger one is The square root roughness is 1 nm or more and 20 nm or less;

[15] The PVA-based polymer film according to [13] or [14] above, which is an elongated PVA-based polymer film;

[16] A film roll obtained by continuously winding a PVA-based polymer film of the above [15] (hereinafter, the film roll is also referred to as "film roll (2)").

[17] A method for producing a polarizing film, wherein the PVA-based polymer film according to any one of [13] to [15] is used as a film roll, which has a dyeing step, a uniaxial stretching step, and a fixing treatment. The step and the drying step are carried out in the last treatment bath before entering the drying step, the angle between the liquid surface of the treatment bath and the film surface is 30° or more and 85° or less, and the upper side of the film is coated with polyvinyl alcohol. a surface having a small root mean square roughness in a polymer film;

[18] A polarizing film produced by the production method of [17] above;

[19] A method for producing a PVA-based polymer film, comprising: a chrome-plated layer having a surface hardness of 550 HV or more and less than 900 HV, and a surface temperature of 50 ° C or more and 115 ° C or less; a process in which a PVA-based polymer in a solution state or a molten state is cast and dried to form a film, and an area in a surface of the metal support before the start of the flow molding of the polyvinyl alcohol-based polymer in a solution state or a molten state ( The product of the maximum width and the distance between the maximum end portions) having a crack number of 200 μm ² or more is 0.7/mm ² or less;

[20] The production method according to the above [19], wherein the PVA-based polymer in a solution state or a molten state comprises a film-forming stock solution of a PVA-based polymer and water. Shape;

[21] The production method according to the above [19] or [20] wherein the degree of polymerization of the PVA-based polymer is 3,000 or more and 10,000 or less;

[22] The method according to any one of [19] to [21] wherein the surface hardness of the metal support has a Vickers hardness of 600 HV or more and less than 800 HV;

[23] The method of any one of the above [19] to [22] wherein the surface temperature of the metal support having a surface hardness of 550 HV or more and less than 900 HV is 0.5 ° C. The temperature change rate of /hour or more is set to be 50 ° C or more and 115 ° C or less;

[24] The method for producing a PVA-based polymer film according to any one of the above [1] to [6] and [13] to [15], wherein the method of producing a PVA-based polymer film according to any one of the above [1] to [6] and [13] to [15] .

According to the present invention, it is possible to provide a PVA-based polymer film which is capable of producing a polarizing film having a small defect and a polarizing plate in a good yield. Further, according to the present invention, it is possible to provide a film roll in which an elongated PVA-based polymer film is continuously wound, which can produce surface characteristics from the winding start portion to the winding end portion of the PVA-based polymer film. Polarized film and polarizing plate with small difference and stable quality.

According to the present invention, it is possible to provide a PVA-based polymer film which is less likely to wrinkle in a film roll and which can easily produce a polarizing film which reduces uneven dyeing, and a film roll which is continuously wound; and a foreign matter for manufacturing A method for producing a polarizing film having a small number of polarizing films and a polarizing film having less foreign matter.

According to the present invention, a method for producing a PVA-based polymer film which can easily produce the PVA-based polymer film and the film roll can be provided.

[Formation of the Invention]

Hereinafter, the present invention will be described in further detail.

[PVA polymer film (1)]

The PVA-based polymer film (PVA-based polymer film (1)) of the present invention has a disadvantage that the recessed area on the surface of the film is 400 μm ² or more and the depth is 0.3 μm or more (hereinafter, this disadvantage is also referred to as "flaw A". The case) is 0.25/m ² or less. The disadvantages of the plastic film include, for example, voids (bubbles) in the film; so-called fisheyes due to the incorporation of foreign matter; the scars generated during the operation of the film (mostly groove-like recesses); The inventors of the present invention have found that the excellent effect of producing a polarizing film and a polarizing plate having a small defect in a good yield can be achieved by controlling the number of the above-mentioned disadvantages A in particular by controlling the number of the above-mentioned disadvantages A. . This disadvantage A is considered to be one of the causes of the convex shape transfer on the above-mentioned film forming apparatus. In particular, as described later, when a PVA-based polymer film is produced using a metal support of a drum or a belt, it is considered to be attached. One of the causes of the foreign matter of the resin deposit on the metal support to transfer the convex shape to the film. For this reason, when the elongated PVA-based polymer film produces the defect A, at least part of the defect A is plural at substantially constant intervals in the longitudinal direction of the film and substantially at the same position in the width direction of the film (for example) 3 or more) tendency to arrange. Wherein, the above-mentioned substantially fixed interval is typically one-minute length (full circumference) corresponding to the metal support of the drum or belt, and depending on the case, there may be a case corresponding to an integral multiple of the length of one minute. Further, since the convex shape of the foreign matter can be formed in a plurality of metal supports, a plurality of groups of the defects A as in the above arrangement may be present.

In the PVA-based polymer film (1) of the present invention described above, the number of defects A must be 0.25/m ² or less. When the number of the disadvantages A exceeds 0.25/m ² , the defects in the polarizing film or the polarizing plate produced thereby increase, and the quality level required in recent years cannot be sufficiently achieved, and the polarizing film or the polarizing plate having many defects is discarded. This results in a decrease in the yield of these products. From such a viewpoint, the number of the defects A is preferably 0.20 / m ² or less, more preferably 0.15 / m ² or less, even more preferably 0.10 / m ² or less, and particularly preferably 0.075 / m ² or less. good.

Further, the lower limit of the number of the defects A is not particularly limited. However, in order to make the number of the defects A extremely small, there is a concern that the cost for installing the film forming apparatus is extremely high, and therefore, the number of the defects A is 0.001. Preferably, it is /m ² or more, more preferably 0.003 / m ² or more, and even more preferably 0.005 / m ² or more.

Disadvantage A is a disadvantage of the surface depression of the film, which is disadvantageous in that the recessed area of the film surface is 400 μm ² or more and the depth is 0.3 μm or more. Here, the defect A is that at least one of the two faces of the film faces the inside of the film. Generally, most of the defect A is recessed toward the inside of the film in contact with the metal support body used in the film formation. Further, the area of the defect A means the area of the opening of the defect A. Further, the depth of the defect A means the depth from the opening of the defect A to the direction perpendicular to the film surface, and the depth of the deepest position.

The number of the defects A (unit: m/m ² ) was found to be the defect A by the end of the PVA-based polymer film to be the target, and the area (unit of the PVA-based polymer film examined by the ten defects A was found. It is determined by dividing m ² ) by 10 (pieces), and specifically, it can be obtained by the following method in the examples. Among them, the judgment of whether each of the disadvantages is the defect A can be performed using a non-contact surface profiler.

The shape of the PVA-based polymer film (1) is not particularly limited, and when the PVA-based polymer film (1) is used as a film roll for producing a polarizing film, the polarizing film can be continuously produced with excellent yield. A long PVA polymer film is preferred.

The length of the long PVA-based polymer film is not particularly limited, and may be appropriately set depending on the use of the PVA-based polymer film (1), and specifically, the length is preferably 1,000 m or more, and 4,000. More preferably m or more, more preferably 6,000 m or more, and particularly preferably 7,000 m or more, and more preferably 8,000 m or more. In particular, according to the method for producing a PVA-based polymer film described below, in addition to the number of defects A of the PVA-based polymer film, and the continuous production of the PVA-based polymer film over a long period of time, the defect A can also be used. Since the fluctuation of the number is maintained at a low level, even when the length is longer (for example, 6,000 m or more), the PVA-based polymer film having a reduced number of defects A can be easily obtained. Further, in the case of a PVA-based polymer film having such a long length, when the polarizing film is continuously produced, the yield can be stably stabilized over a long period of time, the manufacturing defects are small, and the quality level required in recent years can be satisfied, and the replacement can be reduced. The cumbersome and time lost of the film roll. The upper limit of the length of the elongated PVA-based polymer film is not particularly limited, but when it is too long, the weight is made when the film roll is formed. The length of the film is too large, and the operability is lowered to make storage and transportation difficult. Therefore, the length is preferably 30,000 m or less, more preferably 25,000 m or less, and still more preferably 20,000 m or less.

The width of the elongated PVA-based polymer film is not particularly limited, and may be, for example, 0.5 m or more. However, in recent years, a wide polarizing film is required. Therefore, it is preferably 1 m or more, more preferably 2 m or more, and 4 m or more. good. The upper limit of the width of the elongated PVA-based polymer film is not particularly limited. However, when the width is too wide, uniform stretching tends to be difficult when a polarizing film is produced by a practical device, and thus PVA polymerization is performed. The width of the film is preferably 7 m or less.

The thickness of the PVA-based polymer film (1) is not particularly limited, and may be appropriately set depending on the use of the PVA-based polymer film or the like. Specifically, the thickness is preferably 300 μm or less, more preferably 150 μm or less, and 100 μm. The following is even better. Further, in recent years, a thin polarizing film is required. From such a viewpoint, the thickness of the PVA-based polymer film (1) is preferably 45 μm or less, more preferably 35 μm or less, and still more preferably 25 μm or less. The lower limit of the thickness of the PVA-based polymer film (1) is not particularly limited, but a polarizing film or the like can be produced more smoothly, and the thickness is preferably 3 μm or more, more preferably 5 μm or more.

The PVA-based polymer constituting the PVA-based polymer film (1) can be produced by saponification using a vinyl ester-based polymer obtained by polymerizing a vinyl ester-based monomer. Examples of the vinyl ester-based monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, and trimethyl vinyl acetate. Ester, vinyl versatate, etc., etc. Among them, vinyl acetate is preferred.

The vinyl ester-based polymer is preferably one or two or more vinyl ester-based monomers as a monomer, and only one of the vinyl ester-based monomers as a monomer is used. More preferably, a copolymer of one or more vinyl ester monomers and other monomers copolymerizable therewith may be used.

Examples of the other monomer copolymerizable with the vinyl ester monomer may, for example, be ethylene; olefins having a carbon number of 3 to 30 such as propylene, 1-butene or isobutylene; acrylic acid or a salt thereof; methyl acrylate or acrylic acid B. Ester, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, etc.; Acrylic acid or a salt thereof; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid Trimethacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, etc.; acrylamide, N-methyl acrylamide, N-ethyl propylene Indoleamine, N,N-dimethylpropenylamine, diacetone acrylamide, acrylamide sulfonic acid or its salt, acrylamidopropyl dimethylamine or its salt, N-methylol acrylamide a acrylamide derivative such as a derivative thereof; methacrylamide, N-methylmethyl propyl Guanamine, N-ethylmethacrylamide, methacrylamide or its salt, methacrylamide propylamine or its salt, N-methylol methacrylamide or a methacrylamide derivative such as a derivative thereof; N-vinyl decylamine such as N-vinylformamide, N-vinylacetamide or N-vinylpyrrolidone; methyl vinyl ether; Ethyl vinyl ether, positive Propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, etc. Vinyl ether; acrylonitrile such as acrylonitrile or methacrylonitrile; vinyl halide such as vinyl chloride, dichloroethylene, vinyl fluoride or difluoroethylene; propylene-based compound such as propylene acetate or chloropropene; maleic acid or a salt, an ester or an acid anhydride thereof; itaconic acid or a salt thereof, an ester or an acid anhydride thereof; an ethylene decane compound such as ethylene trimethoxyoxane; an isopropenyl acetate or the like. The vinyl ester polymer may have one or two or more structural units derived from the other monomers.

The proportion of the structural unit derived from the above other monomer in the vinyl ester polymer is not particularly limited, and is 15 mol% or less based on the number of moles of all the structural units constituting the vinyl ester polymer. Good, with 5 mol% or less is better.

The degree of polymerization of the PVA-based polymer is not necessarily limited, but the film strength tends to decrease as the degree of polymerization decreases. Therefore, it is preferably 200 or more, more preferably 300 or more, and even more preferably 400 or more, especially 500. The above is especially good. Further, when the degree of polymerization is too high, the viscosity of the aqueous solution or the molten PVA-based polymer is increased, and the film tends to be difficult to form. Therefore, it is preferably 10,000 or less, more preferably 9,000 or less, even more preferably 8,000 or less, and more preferably 7,000. The following is especially good. Here, the degree of polymerization of the PVA-based polymer refers to the average degree of polymerization measured according to the description of JIS K6726-1994, and the PVA-based polymer is further saponified and refined, and the ultimate viscosity [η] measured in water at 30 ° C ( Unit; dl / g), from which the ultimate viscosity [η] is obtained by the following formula.

Degree of polymerization = ([η] × 10 ^{3 /} 8.29) ^(1/0.62)

Also, the degree of polymerization is 3,000 or more and 10,000 or less. When a PVA-based polymer film is produced by the following method, a PVA-based polymer film having a very small number of defects A can be obtained, and a PVA-based polymer film can be continuously formed over a long period of time. It is better to maintain the change in the number of defects A at a lower level. From such a viewpoint, the degree of polymerization of the PVA-based polymer is preferably 4,000 or more, more preferably 5,000 or more. Further, the reason why the above effect is achieved by using a PVA-based polymer having a polymerization degree of 3,000 or more and 10,000 or less is not necessarily clear, but the number of defects A in the PVA-based polymer film is considered to be in a solution state. The case where the PVA-based polymer in a molten state easily penetrates into the crack existing on the surface of the metal support increases, and it is inferred that the penetration of the PVA-based polymer having the above polymerization degree can be suppressed.

The degree of saponification of the PVA-based polymer is not particularly limited. For example, a PVA-based polymer of 60 mol% or more can be used, but a PVA-based polymer film, particularly a polarizing film, is used as a film material for optical film production. The saponification degree of the PVA-based polymer is preferably 95% by mole or more, more preferably 98% by mole or more, and even more preferably 99% by mole or more. Here, the degree of saponification of the PVA-based polymer means a total of a structural unit (usually a vinyl ester monomer unit) and a vinyl alcohol unit which are converted into a vinyl alcohol unit by saponification of a PVA-based polymer. The number of ears, the proportion of the number of moles of the vinyl alcohol unit (% by mole). The degree of saponification of the PVA-based polymer can be measured in accordance with the description in JIS K6726-1994.

When the PVA-based polymer film (1) is produced, one type of PVA-based polymer may be used alone, or one or two or more of the degree of polymerization, the degree of saponification, and the degree of modification may be different from each other. Two or more types of PVA-based polymers are used in combination. Content of PVA-based polymer in PVA-based polymer film (1) The ratio is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 85% by mass or more.

The PVA-based polymer film (1) preferably contains a plasticizer. The PVA-based polymer film (1) can prevent the occurrence of wrinkles when the film roll is formed by including the plasticizer, and improve the passability of the step in the secondary processing. The plasticizer is preferably a polyhydric alcohol, and specific examples thereof include ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylol. Propane, etc. These plasticizers may be used singly or in combination of two or more. Among these plasticizers, ethylene glycol or glycerin is preferred from the viewpoints of compatibility with the PVA-based polymer and availability.

The content of the plasticizer in the PVA-based polymer film (1) is preferably from 1 to 30 parts by mass, more preferably from 3 to 25 parts by mass, per 100 parts by mass of the PVA-based polymer. It is more preferably in the range of 5 to 20 parts by mass.

The PVA-based polymer film (1) preferably contains a surfactant from the viewpoint of improving the releasability of the metal support used in the production of the PVA-based polymer film and improving the handleability of the PVA-based polymer film. The kind of the surfactant is not particularly limited, and an anionic or non-anionic surfactant can be applied.

Examples of the anionic surfactant include a carboxylic acid type such as potassium laurate, a sulfate type such as octyl sulfate, and a sulfonic acid type such as a dodecylbenzenesulfonate type.

Examples of the non-anionic surfactant include alkyl ether type such as polyoxyethyl ether oleyl ether; alkyl phenyl ether type such as polyoxyethyl octyl phenyl ether; Alkyl ester type of lauric acid ester or the like; polyoxygen extension An alkylamine type such as ethyl laurylamine ether; a polyalkylene amine type such as polyoxymethylene ethyl laurate; a polypropylene glycol ether type such as polyoxyethylidene propyl ether; lauric acid An alkanolamine type such as diethanolamine or oleic acid diethanolamine; an allylphenyl ether such as polyoxyalkylene allylic phenyl ether or the like.

These surfactants may be used alone or in combination of two or more.

The content of the surfactant in the PVA-based polymer film (1) is from 0.01 to 100 parts by mass of the PVA-based polymer from the viewpoint of the releasability from the metal support and the handleability of the PVA-based polymer film. It is preferably in the range of 1 part by mass, more preferably in the range of 0.02 to 0.5 part by mass, still more preferably in the range of 0.05 to 0.3 part by mass.

In the PVA-based polymer film (1), other components other than the PVA-based polymer, the plasticizer, and the surfactant may be further contained as necessary. Examples of such other components include water, an antioxidant, an ultraviolet absorber, a lubricant, a colorant, a filler (inorganic particles, starch, etc.), a preservative, an antifungal agent, and other polymers other than the above components. Compounds, etc.

[film roll (1)]

The film roll (film roll (1)) of the present invention is a film roll in which a long PVA-based polymer film is continuously wound, and a winding start portion (a PVA-based polymer film as a film roll) with respect to a PVA-based polymer film. The number of the above-mentioned disadvantages A in the film portion at the start of winding, and the above-mentioned disadvantage A in the winding end portion of the PVA-based polymer film (the film portion at the end of winding of the PVA-based polymer film as a film roll) The number is 1.4 times or less. In such a film roll, due to the winding from the PVA-based polymer film Since the difference in surface characteristics between the initial portion and the end portion of the winding is small, a polarizing film of a stable quality and a polarizing plate can be produced from the film roll. From such a viewpoint, the number of the above-mentioned disadvantages A in the winding end portion of the PVA-based polymer film is preferably 1.3 times or less with respect to the number of the above-mentioned disadvantages A in the winding start portion of the PVA-based polymer film. 1.2 times or less is better, especially 1.1 times or less. Further, in the film formation of the elongated PVA-based polymer film, the number of the defects A tends to increase over time, so that the number of the above-mentioned disadvantages A in the winding start portion of the PVA-based polymer film is The number of the above-mentioned disadvantages A in the winding end portion of the PVA-based polymer film is generally 0.6 times or more, and is wound with respect to the PVA-based polymer film from the viewpoint of producing a polarizing film of stable quality and a polarizing plate. The number of the above-mentioned disadvantages A in the initial portion is preferably 0.7 times or more, more preferably 0.75 times or more, and even more preferably 0.8 times or more, in the winding end portion of the PVA-based polymer film. It is especially good at 0.9 times or more.

In the PVA-based polymer film of the film roll (1) of the present invention, the number of defects A per unit area is not particularly limited, but is satisfied as the number of defects A in the PVA-based polymer film (1) of the present invention. The above number, that is, the number of the defects A is 0.25 pieces/m ² or less (for the upper limit, it is preferably 0.20 pieces/m ² or less, more preferably 0.15 pieces/m ² or less, and 0.10 pieces/m ² or less). More preferably, it is particularly preferably 0.075 pieces/m ² or less; for the lower limit, it is preferably 0.001 / m ² or more, more preferably 0.003 / m ² or more, and even more preferably 0.005 / m ² or more) In the case of continuously producing a polarizing film, it is preferable to stably produce a small defect in a good yield over a long period of time and to satisfy the quality level required in recent years. With respect to the above-mentioned number of defects A per unit area, in the case where both the winding start portion and the winding end portion of the PVA-based polymer film satisfy the above-mentioned number, it is considered that the number satisfies the PVA-based polymer. The entire film.

The length (winding length) of the PVA-based polymer film used in the film roll (1) of the present invention is not particularly limited, and may be appropriately set depending on the use of the PVA-based polymer film or the like. Specifically, the length may be Made more than 1,000m. However, in recent years, in the manufacture of a polarizing film, in order to reduce the cumbersome and time-consuming waste of the film roll, there is a case where a PVA-based polymer film having a length longer than about 4,000 m is required. Even when such a longer PVA-based polymer film is used and the polarizing film is continuously produced over a long period of time, the quality of the product can be stabilized. Therefore, the length of the PVA-based polymer film is preferably 6,000 m or more, and more preferably 7,000 m or more. More preferably, especially more than 8,000m. The upper limit of the length of the long PVA-based polymer film is not particularly limited. However, when the film roll is formed, the workability is lowered due to excessive weight and film roll diameter, and storage and transportation are difficult. Further, since it is difficult to produce a film roll which satisfies the requirements of the present invention, the length is preferably 30,000 m or less, more preferably 25,000 m or less, and still more preferably 20,000 m or less. Further, when the length is 14,000 m or less, particularly 10,000 m or less, it is easier to manufacture a film roll which satisfies the requirements of the present invention.

In the other configuration of the PVA-based polymer film used in the film roll (1) of the present invention, the description of the PVA-based polymer film (1) of the present invention can be made in the same manner as described above, and therefore is omitted here. Repeat the instructions.

The film roll (1) of the present invention is obtained by continuously winding a long PVA polymer film, for example, by continuously winding a long PVA polymer film around a cylindrical core. When a cylindrical core is used, it is preferable that both ends of the core protrude from the end surface of the film roll to form a projection.

The type of the cylindrical core is not particularly limited, and examples thereof include metal products, plastic products, paper products, and wood products. Further, it is also possible to use a core of a composite form using both a metal and a plastic, a metal and a paper, and a plastic and paper. Among these, in consideration of strength, durability, and low dustiness, a core made of metal and/or plastic is preferable, and even if it is repeatedly used, it is not affected by abrasion or the like, so that a metal core is more preferable. Examples of the metal include iron, stainless steel, and aluminum. These may be used alone or in combination of two or more. Further, examples of the plastics include, for example, polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate, polyamide, epoxy resin, polyurethane, polyurea, polyoxyl resin, and the like. One type of these may be used alone or two or more types may be used in combination. Further, the plastic may be a fiber reinforced plastic (FRP) such as carbon fiber reinforced plastic from the viewpoint of strength and the like.

[PVA polymer film (2)]

In the PVA-based polymer film (2) of the present invention, when the root-mean-square roughness is measured on both sides of the film, the root mean square roughness of the two is obtained. The difference is 0.3 nm or more and 10 nm or less, and the smaller one has a root mean square roughness of 10 nm or less. In the conventional film roll in which the PVA-based polymer film is continuously wound, it is easy to cause wrinkles in the film due to poor lubricity between the film rolls. However, the occurrence of the wrinkles can be reduced by using the PVA-based polymer film (2) of the present invention. Further, the wrinkles of the polymer film are those in which the PVA-based polymer film is produced during winding, and the stress remaining in the PVA-based polymer film when the film is wound in a warehouse or the like after being formed into a film roll. In the case where the winding is too tight, and the poor lubricity between the films occurs, the PVA-based polymer film (2) of the present invention can effectively reduce the occurrence of wrinkles of the former, and can also be Reduce the occurrence of wrinkles in the latter. Further, by using the PVA-based polymer film (2) of the present invention, it is possible to easily produce a polarizing film having a reduced uneven dyeing unevenness as described above.

The root mean square roughness of the present invention refers to the root mean square roughness (Rq) according to JIS BO601:2001, and the roughness curve obtained from the surface of the film can be obtained by the average line to the roughness curve. The square of the deviation is averaged and obtained. The root mean square roughness of each of both sides of the PVA-based polymer film can be measured in the following manner in the following manner.

In the PVA-based polymer film (2) of the present invention, when the root mean square roughness is measured on both surfaces of the film, the difference between the two root mean square roughness obtained is required to be 0.3 nm or more and 10 nm or less. When the difference between the two is 0.3 nm or more, the occurrence of wrinkles in the film roll can be effectively reduced. On the other hand, when the difference between the two is 10 nm or less, the uneven dyeing in the polarizing film can be effectively reduced. From such a viewpoint, the difference between the two is preferably 0.5 nm or more, more preferably 0.8 nm or more, more preferably 1.2 nm or more, particularly preferably 1.5 nm or more, and most preferably 2 nm or more, and 7 nm or less. Preferably, it is preferably 5 nm or less.

In the PVA-based polymer film (2) of the present invention, the smaller ones are The square root roughness must be 10 nm or less. When the smaller root mean square roughness is 10 nm or less, the uneven dyeing in the polarizing film can be effectively reduced. From this point of view, the smaller root mean square roughness is preferably 8 nm or less, more preferably 6 nm or less, and still more preferably 4 nm or less. Further, in order to extremely reduce the root mean square roughness and perform special processing, the production cost of the PVA-based polymer film is easily increased. Therefore, the smaller root mean square roughness is preferably 0.3 nm or more, and 0.6. It is more preferably nm or more, more preferably 0.9 nm or more, and particularly preferably 1.2 nm or more.

In the PVA-based polymer film (2), a large root mean square roughness is preferably 1 nm or more and 20 nm or less. When the larger root mean square roughness is above 1 nm, the occurrence of wrinkles in the film roll can be effectively reduced. On the other hand, when the large root mean square roughness is 20 nm or less, the uneven dyeing in the polarizing film can be effectively reduced. From such a viewpoint, a larger root mean square roughness is preferably 2 nm or more, more preferably 4 nm or more, more preferably 15 nm or less, particularly preferably 11 nm or less, and particularly preferably 8 nm or less, and 6 nm or less. For the best.

The shape of the PVA-based polymer film (2) is not particularly limited, and the PVA-based polymer film (2) is used as a film roll for producing a polarizing film, and the polarizing film or the like is continuously produced because of good productivity. A long PVA polymer film is preferred.

The length of the elongated PVA-based polymer film is not particularly limited, and may be appropriately set depending on the use of the PVA-based polymer film (2), and specifically, the length is preferably 1,000 m or more, and 4,000 m. More preferably, it is more preferably 6,000 m or more, more preferably 7,000 m or more, and most preferably 8,000 m or more. If such a longer PVA polymer film is used, ie It can reduce the cumbersome and time waste caused by the replacement of the film roll. The upper limit of the length of the long PVA-based polymer film is not particularly limited. However, when the film roll is too long, the weight and the winding diameter are too large, and the handling property is lowered, which makes it difficult to store and transport the film. The length is preferably 30,000 m or less, more preferably 25,000 m or less, and even more preferably 20,000 m or less. Further, one of the causes of wrinkles in the storage of the film roll is, for example, a stress that remains in the PVA-based polymer film, which causes the winding to be too tight, but the winding is too tight and tends to be longer and wider in the PVA system. The polymer film is strongly present, so that the effect of the present invention can be more significantly achieved in a longer PVA-based polymer film.

The width of the elongated PVA-based polymer film is not particularly limited, and may be, for example, 0.5 m or more. However, in recent years, a polarizing film having a wide width has been sought. Therefore, it is preferably 1 m or more, more preferably 2 m or more, and 4 m or more. good. The upper limit of the width of the elongated PVA-based polymer film is not particularly limited. However, when the width is too wide, when a polarizing film or the like is produced by a practical device, the uniform stretching tends to be difficult, so the PVA polymerization is performed. The width of the film is preferably 7 m or less. In addition, as described for the length of the PVA-based polymer film, the over-tightening tends to occur remarkably in the longer and wider PVA-based polymer film, so that it is more remarkable in the wider PVA-based polymer film. The effect of the present invention is achieved.

The thickness of the PVA-based polymer film (2) is not particularly limited, and may be appropriately set depending on the use of the PVA-based polymer film or the like. Specifically, the thickness is preferably 300 μm or less, more preferably 150 μm or less, and 100 μm or less. Better yet. Further, in recent years, a thinner polarizing film has also been demanded, and from such a viewpoint, the thickness of the PVA-based polymer film (2) is It is preferably 45 μm or less, more preferably 35 μm or less, and even more preferably 25 μm or less. The lower limit of the thickness of the PVA-based polymer film (2) is not particularly limited, and a polarizing film or the like can be produced smoothly, and the thickness is preferably 3 μm or more, more preferably 5 μm or more. Further, since the wrinkle-based PVA-based polymer film in the film roll is thinner and thinner, the effect of the present invention can be more significantly achieved in a thinner PVA-based polymer film.

The other configuration of the PVA-based polymer film (2) of the present invention can be made the same as that of the PVA-based polymer film (1) of the present invention, and thus the description thereof will not be repeated.

The production method of the PVA-based polymer film (2) is not particularly limited. For example, according to the method for producing a PVA-based polymer film of the present invention, the intended PVA-based polymer film (2) can be easily produced. good. At this time, the side to which the surface of the metal support is joined is likely to be a surface having a large root mean square roughness. In addition to the production method, it is considered that there are also methods for passing a PVA-based polymer film formed by forming a metal roll having different surface roughness, and a method for producing a PVA-based polymer film. The foreign matter in the film stock solution (deteriorated resin or contamination from the outside) is removed by a filter or the like, and the ultrafine particles of the inorganic substance are added to the film forming stock solution to form a film on the smooth surface, and the root mean square roughness of both surfaces is adjusted.

[film roll (2)]

The film roll (film roll (2)) of the present invention is a PVA polymer film (2) as described above, which is formed by continuously winding an elongated PVA polymer film, for example, a PVA in a cylindrical core. The elongated PVA-based polymer film of the polymer film (2) is continuously wound. When using a cylindrical core It is preferable that both end portions of the core have a protruding portion that protrudes from the end surface of the film roll. The core described above can be used as described in the film roll (1). Repeated descriptions may be omitted herein.

The other constitution of the film roll (2) of the present invention may be the same as that of the film roll (1) of the present invention, and thus the overlapping description will be omitted.

In the film roll (2) of the present invention, wrinkles which are likely to occur in the conventional film roll during storage can be reduced. When the temperature of the film roll is too high, the PVA-based polymer film is likely to wrinkle due to deformation, and therefore it is preferably 40 ° C or lower, more preferably 35 ° C or lower, and even more preferably 30 ° C or lower. Further, the lower limit of the temperature at the time of storing the film roll is not particularly limited, but the temperature is preferably -10 ° C or more, more preferably -5 ° C or more, and still more preferably 0 ° C or more.

[Method for Producing PVA-Based Polymer Film]

The manufacturing method of the present invention for producing a PVA-based polymer film has a chrome-plated layer on the surface, a Vickers hardness of 550 HV or more and a surface hardness of less than 900 HV, and a surface temperature of 50 ° C or more and 115 ° C or less. A step of forming a film by casting and drying a polyvinyl alcohol-based polymer in a solution state or a molten state. Further, before the PVA-based polymer in a solution state or a molten state is started to be casted, the number of cracks in the area (the product of the maximum width and the maximum end distance) in the surface of the metal support of 200 μm ² or more is 0.7/ Below mm ² . According to the production method, the PVA-based polymer film (PVA-based polymer film (1) and (2)) of the present invention can be easily produced, and the film roll (film roll (1) and (2) of the present invention can be easily produced. )) An elongated PVA-based polymer film continuously wound.

The metal support used in the present invention may, for example, be a drum or a belt having a chrome plating layer on the surface, wherein the surface of the metal support means a surface of a PVA-based polymer cast in a solution state or a molten state (film formation) When the metal support is a drum, the chrome-plated layer may be provided on the outer surface of the drum, and if it is a belt, the chrome-plated layer may be provided on the outer side of the continuous surface of the belt.

The thickness of the chrome plating layer is not particularly limited, but the corrosion of the surface of the metal support can be more effectively prevented, and the number of cracks described below can be easily reduced. Therefore, it is preferably in the range of 10 μm or more and 500 μm or less. Moreover, the chrome plating layer may be formed once, or may be formed into a plurality of times. For example, when the chrome plating layer is formed into a plurality of times, after the chrome plating layer is formed, the surface unevenness is removed by grinding, and further chrome plating is formed thereon. The layer can be. When this is done, the pinholes of the chrome layer can be reduced. Further, as described in Patent Document 4 or the like, if a nickel plating layer is provided under the chrome plating layer, the crack in the chrome plating layer can be further reduced.

In the above metal support having a chrome plating layer on the surface, the Vickers hardness of the surface hardness needs to be 550 HV or more and less than 900 HV. A metal support having a chrome plating layer is generally known (for example, refer to Patent Documents 4 to 7, etc.), and when a metal support having a specific surface hardness of the present invention is used, although the reason is unknown, it is polished by, for example, polishing. Before the film formation is started, the surface of the metal support can be easily treated to reduce the number of cracks present on the surface of the metal support, and the above disadvantages can be further reduced in the PVA polymer film obtained. In addition, even if the PVA-based polymer film is continuously formed over a long period of time, it is ensured that the variation of the above-mentioned disadvantage A is lower than the usual level. Moreover, two of the films can be The root mean square roughness of the face is adjusted to the required range. When the Vickers hardness of the surface hardness is 900 HV or more, it is difficult to reduce the number of cracks present on the surface of the metal support, and when the PVA-based polymer film is continuously formed over a long period of time, the number of the above-mentioned disadvantages A is The increase is increased. In addition, the root mean square roughness of both sides of the film is not easily within the required range. From the above viewpoint, the Vickers hardness of the surface hardness is preferably less than 800 HV, more preferably less than 780 HV. Further, when the Vickers hardness of the surface hardness is less than 550 HV, problems such as scratches are likely to occur during continuous film formation and when cleaning the surface of the metal support, and the PVA-based polymer film is also formed continuously over a long period of time. The variation in the number of the above disadvantages A is increased. In addition, the root mean square roughness of both sides of the film is not easily within the required range. From such a viewpoint, the Vickers hardness of the surface hardness is preferably 600 HV or more, more preferably 650 HV or more, and still more preferably 700 HV or more.

The surface hardness of the metal support is determined by using a durometer or the like, and the Vickers hardness of the surface of the chrome plating layer is measured at a plurality of points, and can be obtained by averaging these. Further, the surface hardness (Vickers hardness) can be measured by casting a surface of a PVA-based polymer in a molten state or a molten state (film-forming surface), but the flaw generated during the measurement causes the obtained PVA-based polymer film. The quality is lowered, and therefore, even in the vicinity of the surface (film-forming surface) of the PVA-based polymer in which a solution state or a molten state is formed in a portion where a chrome layer is formed in the end portion of the drum or the belt, or in a cast molding The surface (film-forming surface) of the PVA-based polymer in a solution state or a molten state is measured, and the surface hardness is measured on the surface of the film portion which is removed by trimming or the like after the film formation, and the value thereof can be regarded as the present invention. The specified surface hardness. Metal support The surface hardness, specifically, can be obtained in the examples by the following method.

The adjustment of the surface hardness of the metal support having a chrome plating layer on the surface can be easily carried out according to a conventional method, and can be specifically carried out by adjusting the temperature of the chrome plating bath used in the chrome plating treatment to a specific range. Method; method for adjusting the current density during chrome plating to a specific range; adjusting the composition of the chrome bath; after chrome treatment, the adsorption in the chrome layer can be adjusted by heat treatment (annealing) or hydrogen exposure Method of hydrogen concentration, etc. Among these, since the operation is simple, etc., it is preferable to adjust the temperature of the chrome plating bath to a specific range, to adjust the current density during chrome plating to a specific range, and to adjust the adsorption after chrome plating. The method of adjusting the hydrogen concentration in the chrome plating layer is preferably carried out by adjusting the temperature of the chrome plating bath to a specific range. Regarding the above method, a chromic acid-sulfuric acid aqueous solution of a general chrome plating bath is used, for example, the temperature of the chrome plating bath is in the range of 40 ° C or more and 70 ° C or less, and the current density is chrome plating in the range of 60 A/dm ² or less. At the time of treatment, the higher the temperature of the chrome bath and the lower the current density, the tendency of the surface hardness to be substantially lower. Further, regarding the concentration of hydrogen adsorbed in the chromium plating layer, the temperature of the heat treatment is increased, the treatment time is increased, and the concentration is lowered, and the surface hardness tends to be substantially lower.

The method for forming the chrome plating layer is not particularly limited as long as it can be a metal support having a surface hardness satisfying the above range, but a conventional method can be employed, and representative methods thereof can be exemplified as follows: First, a metal support is used. The surface is polished by polishing or grinding, etc., and the surface irregularities are removed as much as possible, and then preliminary treatment such as immersion degreasing, electrolytic degreasing, aqueous hydrochloric acid immersion, etc., and then a chrome plating bath is used. A method of performing chrome treatment and further heat treatment. The chrome bath is represented by the Sargent bath and can be used as appropriate. Examples of the composition of the Sargent bath and the conditions of the chrome treatment are as follows.

<Composition of the Sargent Bath>

Chromic anhydride: 100 to 300 g / L (concentration using the drug standard)

Sulfuric acid: 1/50 to 1/150 (mass ratio) of the chromic anhydride used

<The conditions of chrome plating>

Current density 10 to 60 A/dm ²

The temperature of the chrome bath is greatly affected by the surface hardness of the metal support obtained as described above. The specific temperature of the chrome bath varies depending on other conditions used in the chrome plating treatment or the heat treatment conditions after the chrome treatment, but preferably 50° C. or higher, more preferably 53° C. or higher, and particularly preferably 54° C. or higher. . When the temperature of the chrome plating bath is too low, the surface hardness of the obtained metal support tends to become excessively high. Further, the temperature of the chrome plating bath is preferably 66 ° C or less, more preferably 63 ° C or less, particularly preferably 61 ° C or less, and particularly preferably 58 ° C or less. When the temperature of the chrome plating bath is too high, the surface hardness of the obtained metal support tends to be too low.

It is preferred to perform heat treatment (annealing) after chrome plating. When the heat treatment is performed at a high temperature, the required time can be shortened. However, when the temperature is too high, cracks are likely to occur in the chrome plating layer. Therefore, the heat treatment temperature is preferably 130 ° C or less, more preferably 120 ° C or less. On the other hand, when heat treatment is performed at a low temperature, the risk of cracking is lowered, but it is necessary to lengthen the time required for the heat treatment, so the heat treatment temperature is preferably 70 ° C or more, more preferably 90 ° C or more. The heat treatment time varies depending on the conditions of the chrome treatment and the temperature of the heat treatment, but can be set within the range of 24 to 120 hours.

The PVA-based polymer in a solution state or a molten state may, for example, be a film-forming stock solution in which a PVA-based polymer is dissolved in a liquid medium, or a film-forming stock solution containing a PVA-based polymer and a liquid medium and a PVA-based polymer melted. The form of the film forming stock solution containing the PVA polymer and the liquid medium. The film forming stock solution may further contain a plasticizer, a surfactant, and other components as described above as needed.

Examples of the above liquid medium in the film forming solution may be, for example, water, dimethyl hydrazine, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, or propylene. One or two or more of these may be used as the alcohol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine or diethylenetriamine. Among them, water is preferred from the viewpoint of environmental load and recycling. In other words, a preferred example of the PVA-based polymer in a solution state or a molten state is a form including a film-forming stock solution of a PVA-based polymer and water.

The volatilization ratio of the film-forming stock solution (the content of the film-forming stock solution in which the volatile component such as the liquid medium is removed by volatilization or evaporation at the time of film formation) varies depending on the film forming method, the film forming conditions, and the like. It is preferably in the range of 50 to 90% by mass, more preferably in the range of 55 to 80% by mass. When the volatilization ratio of the film forming stock solution is 50% by mass or more, the viscosity of the film forming raw liquid is not excessively high, and the filtration and defoaming at the time of preparing the film forming raw liquid are smoothly performed, whereby foreign matter can be easily produced and the defects are few. PVA polymer film. In addition, the PVA-based polymer film for industrial use can be easily produced by making the concentration of the film-forming stock solution 90% by mass or less and the concentration of the film-forming stock solution is not too low.

The preparation method of the above film forming stock solution is not particularly limited, but For example, a method in which a PVA-based polymer is dissolved in a liquid medium such as water, and at least one of a plasticizer, a surfactant, and other components may be added as needed, and A method in which a PVA-based polymer containing a liquid medium such as water is melt-kneaded in an extruder, and at this time, it can be melt-kneaded together with at least one of a plasticizer, a surfactant, and other components as needed. Wait.

In the production method of the present invention for producing a PVA-based polymer film, the PVA-based polymer in the solution state or the molten state is cast on the surface of the metal support having a surface temperature of 50 ° C or more and 115 ° C or less. It is a step of drying to form a film. When the surface temperature of the metal support exceeds 115 ° C, the number of defects A in the obtained PVA-based polymer film increases. Moreover, the root mean square roughness of both sides of the film is likely to exceed the required range. From this point of view, the surface temperature of the metal support is preferably 105 ° C or lower, more preferably 102 ° C or lower, more preferably 99 ° C or lower, and particularly preferably 96 ° C or lower, and more preferably 95 ° C or lower. On the other hand, when the surface temperature of the metal support is less than 50 ° C, it is difficult for the film to be peeled off from the metal support or to easily cause problems such as the transparency of the film. From such a viewpoint, the surface temperature of the metal support is preferably 60 ° C or more, more preferably 70 ° C or more, and still more preferably 80 ° C or more. Further, the surface temperature of the metal support may be an average value (average temperature) of the surface temperatures of any of a plurality of places (for example, 10 or more) on the surface of the metal support.

Before the film formation starts, the method of setting the surface temperature of the metal support within the above range is not particularly limited. For example, when the drum is used as a metal support, heat of water, oil, water vapor, or the like may be used inside the drum. The medium is heated by an induction heater disposed inside the drum, or A method of heating an infrared heater or a hot air heating device provided to face the surface of the drum.

Before the film formation, the temperature change rate when the surface temperature of the metal support is within the above range, for example, as described in Patent Document 5, may be set to 3 ° C / hour or less, but has a chrome plating layer on the use surface, and has In the method for producing a metal support having the above surface hardness, although it is not known, it is found that the increase in the number of cracks existing on the surface of the metal support can be suppressed even if the temperature change rate is increased, even if the temperature adjustment time is cut off. When the productivity is improved, the number of the above-mentioned disadvantages A in the obtained PVA-based polymer film can be suppressed to be controlled at a low level. From this point of view, the temperature change rate when the surface temperature of the metal support is set within the above range before the film formation is preferably 0.5 ° C / hour or more, more preferably 1 ° C / hour or more, or 3.5 ° C / More than hours, 4 ° C / hour or more, 4.5 ° C / hour or more, and 5 ° C / hour or more. Further, the temperature change rate is preferably 10 ° C /hr or less, and more preferably 7 ° C /hr or less from the viewpoint of reducing the number of cracks.

When the surface temperature of the metal support is set within the above range before the film formation is started, the temperature difference in the width direction of the metal support is reduced, and it is preferable from the viewpoint of reducing the number of cracks, specifically, metal support. The surface temperature of the body is continuously measured in the width direction. When the temperature distribution data is obtained as a horizontal axis and the temperature is a vertical axis, the maximum value of the absolute value of the slope is 10 ° C / m or less. Preferably, it is preferably 5 ° C / m or less, more preferably 4 ° C / m or less, and more preferably 3 ° C / m or less.

Further, in the production method of the present invention for producing a PVA-based polymer film, the polyvinyl alcohol-based polymer in a solution state or a molten state has a crack in an area of 200 μm ² or more on the surface of the metal support before starting the casting. The number is below 0.7/mm ² . The crack area here refers to the product of the maximum width of the crack and the distance between the largest ends. Usually, cracks such as cracks in the chrome plating layer are present on the surface of the metal support before the film formation starts. In the film formation, a foreign matter which is considered to be a resin deposit is gradually adhered to the crack, and a convex shape is formed, which is considered to be a defect A in which the convex shape is transferred to the film to form a film. In particular, when the PVA polymer is compared with other polymers, it has high hydrophilicity and good affinity with metals. Therefore, it is considered that cracks on the surface of the metal support are likely to adhere to the resin deposit, and it is considered to be When the dried film is peeled off from the metal support, it is easy to form a convex shape and increase it. For this reason, in order to reduce the number of defects A, it is preferable to reduce the number of cracks present on the surface of the metal support as much as possible, but as described above, the metal support having the chrome-plated layer on the surface and having the above surface hardness is used. In the case of a body, although the general treatment performed on the surface of the metal support before the film formation such as polishing or polishing is started, the number of cracks existing on the surface of the metal support can be easily reduced, and the obtained PVA system can be lowered as usual. The number of the above-mentioned disadvantages A in the polymer film, and the PVA-based polymer film can ensure that the fluctuation of the number of the above-mentioned defects A is lower than usual even if the film is continuously formed over a long period of time. When the number of cracks on the surface of the metal support exceeds 0.7/mm ² , the number of the above-mentioned disadvantages A in the obtained PVA-based polymer film increases. From the viewpoint of reducing the number of defects A in the obtained PVA-based polymer film, etc., the number of cracks on the surface of the metal support before the start of casting of the PVA-based polymer in a solution state or a molten state is 0.3/mm ² or less. Preferably, it is preferably 0.15 pieces/mm ² or less. On the other hand, the number of cracks is extremely reduced above the surface of the metal solid support is complicated, and the effect also reaches the peak of the tendency, so that the number of cracks at 0.005 / mm ² or more preferably, to 0.01 / mm ² or more Better.

Surface area of the metallic support 200μm ² over a predetermined coefficient crack 25 at the surface of the metal support of each of them, using a microscope, specifying the range of 2mm × 2mm (4mm ²⁾ the sum of "the area of 200μm ² or more The number of cracks was determined by counting the number of "cracks having an area of 200 μm ² or more" in the range of 4 mm ² × 25, and calculating the number per 1 mm ² . Wherein, the area of the crack refers to the product of the maximum width and the maximum end distance among the cracks, and the distance between the maximum ends refers to the distance between the ends when the end of the crack is only two. (straight line distance), as in the plural, the maximum distance between the ends of the complex number. The number of cracks in the surface of the metal support having an area of 200 μm ² or more can be specifically determined by the method described in the examples.

The width of the metal support can be appropriately set in accordance with the width of the intended PVA-based polymer film. The specific width of the metal support is also different depending on the width of the intended PVA-based polymer film, for example, 0.5 m or more, and from the viewpoint of efficiently producing a PVA-based polymer film which can be made into a wide polarizing film width. It is preferably 4.5 m or more, more preferably 5.0 m or more, and even more preferably 5.5 m or more. Further, in consideration of the cost of the metal support and the ease of maintenance, the width of the metal support is preferably 7.5 m or less, more preferably 7.0 m or less, and even more preferably 6.5 m or less.

The method of casting the PVA-based polymer in a solution state or a molten state on the surface of the metal support is not particularly limited, and a T-type narrow can be used. The slit die, the feed hopper plate, the I die, and the lip coater die are subjected to conventional methods. Further, the temperature of the PVA-based polymer in a molten state or a solution state is preferably in the range of 50 ° C or more and 105 ° C or less.

Drying after casting can be carried out by a conventional method, dried by heat imparted by a metal support, or dried by blowing hot air. Further, the desired PVA-based polymer film can be produced only by drying on the surface of the metal support, but is partially dried on the surface of the metal support by a conventional method or the like, and then disposed on the metal support. Further, one or two or more drying rolls or hot air dryers in which the metal support and the rotating shaft are parallel to each other are further dried, and a desired PVA-based polymer film can be produced.

The PVA-based polymer film obtained in this manner may be subjected to heat treatment as necessary or may be cut at both end portions (side portions) in the width direction. Further, a continuously wound film roll can also be produced as described above.

[use]

The PVA-based polymer film of the present invention (PVA-based polymer films (1) and (2)) and the PVA-based polymer film which is obtained by the film roll (film roll (1) and (2)) of the present invention are Use: The number of defects A is small, the quality is stable; the advantages of wrinkles and the like are less likely to occur, and it is used in various applications, but the effect of the present invention can be more significantly achieved to use an optical film as a polarizing film or a retardation film. A film roll for production is preferred, and it is more preferable to use a film roll for use as a polarizing film.

The method of using the PVA-based polymer film as a film roll and producing a polarizing film is not particularly limited, and a conventional method can be employed. For example, the PVA-based polymer film can be used for dyeing and uniaxial drawing. Stretching, fixing treatment and drying, and further cleaning and heat treatment according to the needs. Here, the order of each treatment such as dyeing, uniaxial stretching, and fixing treatment is not particularly limited, and one or two or more kinds of treatments may be simultaneously performed. Further, one or two or more treatments may be carried out two or more times, and for example, uniaxial stretching may be carried out two or more times. The boring treatment may be performed as necessary before performing various processes such as dyeing, uniaxial stretching, and fixing treatment.

The dyeing can be carried out at any stage before uniaxial stretching, uniaxial stretching, or after uniaxial stretching. The dye used for dyeing can be used: iodine-potassium iodide; direct black 17, 19, 154; direct brown 44, 106, 195, 210, 223; direct red 2, 23, 28, 31, 37, 39, 79, 81, 240, 242, 247; direct blue 1, 15, 22, 78, 90, 98, 151, 168, 202, 236, 249, 270; direct purple 9, 12, 51, 98; direct green 1, 85; direct yellow 8, 12, 44, 86, 87; one or two or more of the dichroic dyes such as oranges 26, 39, 106, and 107. The dyeing system can be carried out by immersing the PVA-based polymer film in a solution (dyeing bath) containing the above dye. Further, when the PVA-based polymer film is produced, the above dye may be contained in advance.

The uniaxial stretching may be carried out by any one of a wet stretching method or a dry heat stretching method, and may be carried out in warm water (including the above dye bath and a fixed treatment bath described below), or a PVA polymer after water absorption may be used. The film is carried out in air.

The temperature at the time of uniaxial stretching is not particularly limited, but when the PVA-based polymer film is uniaxially stretched (wet-stretched) in warm water, it is preferably in the range of 30° C. or more and 90° C. or less. When dry hot stretching, at 50 ° C It is preferably in the range of 180 ° C or less.

The stretching ratio of the uniaxial stretching (the total of the stretching ratio at the time of uniaxial stretching in the multi-stage stretching) is preferably 4 times or more from the viewpoint of the polarizing performance, and more preferably 5 times or more. The upper limit of the stretching ratio is not particularly limited, but it is preferably 8 times or less and can be stably and easily uniaxially stretched. The thickness of the film after the uniaxial stretching varies depending on the thickness of the PVA-based polymer film to be used, and is preferably in the range of 3 μm or more and 75 μm or less, and more preferably in the range of 5 μm or more and 50 μm or less.

For the purpose of strongly adsorbing the above dye to the PVA-based polymer film, many of them are subjected to a fixing treatment. One or two or more aqueous solutions containing a boron compound such as boric acid or borax may be used as the fixed treatment bath used in the fixing treatment. In the fixed treatment bath, an iodine compound may be added as necessary.

After the respective treatments such as dyeing, uniaxial stretching, and fixing treatment, it is preferred to perform cleaning in order to remove the treatment bath and foreign matter attached to each surface of the film before drying. Pure water can be used for the cleaning liquid used for washing, and water for adding a small amount of these chemicals can be used to suppress the outflow of the dye and the boron compound during washing. The cleaning liquid may be sprayed or the like to spray the surface of each treated film, or the treated film may be immersed in the cleaning bath.

The drying and the heat treatment are preferably carried out in the range of 30 ° C or more and 150 ° C or less, and more preferably in the range of 50 ° C or more and 150 ° C or less.

A PVA-based polymer film (2) and a PVA-based polymer film wound from a film roll (2) are used as a film material for producing a polarizing film. Rolling, and manufacturing the polarizing film through the steps of the dyeing step, the uniaxial stretching step, the fixing treatment step, and the drying step, in the final treatment bath (for example, a fixed treatment bath or a cleaning bath, etc.) before entering the drying step When taken out, the angle between the liquid surface of the treatment bath and the film surface (the angle on the acute angle side) is 30° or more and 85° or less, and the surface on the upper side of the film is used as a PVA-based polymer film for the film roll. In the case of a surface having a smaller root mean square roughness, a polarizing film having less foreign matter can be easily obtained, and thus it is preferable.

The reason for achieving the above effects is not clear. However, it is considered that the polarizing film is produced as described above, and the PVA-based polymer deposited in each treatment bath and the treatment liquid used in each treatment are reduced. When it is taken out in the last treatment bath before the drying step, the angle between the liquid surface of the treatment bath and the film surface is too large or too small, and the deposited PVA polymer and the treatment liquid are easily adhered to ‧ The angle is preferably 35° or more, more preferably 40° or more, still more preferably 50° or more, and most preferably 80° or less, more preferably 75° or less, and still more preferably 70° or less.

The polarizing film obtained by the above operation is generally used as a polarizing plate by bonding the two surfaces or one surface with an optically transparent protective film having mechanical strength. As the protective film, a cellulose triacetate (TAC) film, a cellulose acetate butyrate (CAB) film, an acrylic film, a polyester film, or the like can be used. Further, examples of the adhesive to be bonded include a PVA-based adhesive and an urethane-based adhesive. Among them, a PVA-based adhesive is preferred.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the invention is not limited thereto. Further, the respective measurement or evaluation methods used in the following preparation examples, examples, reference examples, and comparative examples are as follows.

[Determination of Surface Hardness of Roller for Film Making]

In the surface (peripheral surface) of the film forming drum, each of the two sides enters a line of 5 mm inside from the both ends, and the entire circumference of the film forming drum is divided into four equal parts, and each end is fixed at 4 points and 8 points in total. . Further, in each point, the UCI type hardness meter MIC10 (manufactured by GE Sensing & Inspection Technologys Co., Ltd.; probe system using MIC-2101-A) measures the Vickers hardness of the surface of the chrome plating layer, and the average value of these is made. The surface hardness of the film drum.

[Measurement of the number of cracks in the surface of the film forming drum of 200 μm ² or more]

The surface of the film-making drum (peripheral surface) was arbitrarily designated at 25 places, and each of them was photographed at a magnification of 1000 times in a range of 2 mm × 2 mm (4 mm ² ) using Digital video microscopy VHX-900 (manufactured by Keyence). A photo of a crack (a crack on a chrome layer). Moreover, the maximum width of each crack and the distance between the maximum ends can be seen in the photograph (when the end is only 2, it refers to the distance between the ends of the cracks, and if it is plural, it refers to the plurality of ends) The maximum distance between the inter-part distances is obtained by calculating the product in μm, and the product having a thickness of 200 μm ² or more is "crack having an area of 200 μm ² or more". In this way, the number of "cracks having an area of 200 μm ² or more" was obtained in the range of 4 mm from the above-mentioned range of 4 mm ² , and the number per 1 mm ² was calculated therefrom.

[Determination of surface temperature of film forming drum]

It is determined that the first straight line in the width direction of any one point on the surface (peripheral surface) of the film forming drum and the one straight line parallel to the one line are divided into three other straight lines of four equal parts (that is, The film forming drum was placed on the same straight line every 1/4 of a week, and the temperature distribution in the four straight lines was measured using a heat trace TH9100MR (manufactured by NEC Avio Infrared Technology Co., Ltd.). Next, from the obtained temperature distribution data, the temperature of each of the three points (the total of 12 points) at the center portion in the width direction and the position from the both end portions toward the center portion of 20 cm was obtained for each straight line, and the average temperature of the 12 points was averaged. The value is the surface temperature of the film forming drum at this time. Further, the temperature distribution data of each of the obtained straight lines is formed into four curves having the horizontal axis position in the width direction and the vertical axis as the temperature, and the maximum value of the absolute value of the slope is obtained, and this is taken as the time. The maximum temperature gradient of the film forming drum.

[Determination of the number of defects of PVA film]

When the film roll was taken up, the distortion of the fluorescent lamp image when the fluorescent lamp placed behind it was seen through the film, the defect of the film was found, and the oily magic pen circle was circled around it. Then, the defects found were observed by a non-contact surface profiler "NewView" 6300 (manufactured by Zygo Co., Ltd.), and it was judged whether the defect of the surface of the film was such that the area (opening area) was 400 μm ² or more and the depth was 0.3 μm. The above shortcomings (disadvantage A). The above operation was started from the winding end portion of the produced film roll (and the portion from the end portion in the longitudinal direction of the film to 10 m in order to reduce the error), and the PVA film having the number of defects A was determined to be 10 pieces. The area (the length from the start of the operation to the tenth defect A × the width of the film; the unit is m ² ), and the area is divided by 10 (pieces), and the number of defects A in the winding end portion is obtained ( The unit is /m ² ). Further, in the ten disadvantages A, the position in the longitudinal direction of the film is substantially the same, and the interval between the longitudinal direction of the film and the integral value of the entire circumference of the entire film forming drum used are in agreement with each other. The above disadvantages (hereinafter also referred to as "rotation cycle defects"), and such disadvantages include portions other than the portion to be measured, which is considered to be substantially fixed in the longitudinal direction of the film (film transfer) The number of times (inclusive of three or more) of the entire circumference of the cylinder is divided by the above-mentioned area (unit: m ² ), and the number of defects of the rotation period in the winding end portion is determined (unit: m/m ² ).

Next, after the remaining film roll was used and a polarizing film (a polarizing film made of a PVA film on the winding end portion side) was produced as follows, a PVA film was wound up from a residual film of a majority of the PVA film in an unused state. And rewinding into a new film roll, whereby the winding start portion of the original film roll is located outside the new film roll. Using the new film roll, the same operation as described above was carried out, and the defect A in the winding start portion of the original film roll and the number of defects in the rotation cycle (each unit is /m ² ) were obtained, and the residual film roll was used. A polarizing film (a polarizing film manufactured from a PVA film on the winding start portion side) as described below was produced.

[Evaluation of wrinkles in film rolls]

The film roll was observed with the naked eye, and the wrinkles were evaluated on the following basis.

A: No wrinkles were observed

B: There are only some slight wrinkles, but it is a level of no problem in use.

C: There is a wrinkle that becomes a level of use.

[Determination of Root Mean Square Roughness of PVA Film]

The root mean square roughness of any ten of the surface of the PVA film was measured using a white interference microscope NV6300 (manufactured by Zygo Co., Ltd.), and the flatness was measured. The mean is the root mean square roughness of its face. Next, the same operation was performed on the other side of the PVA film to obtain a root mean square roughness.

[Evaluation of Polarized Film (20 Tests)]

The PVA film obtained by winding the film roll was continuously treated to form a polarizing film in the order of preliminary swelling, dyeing, uniaxial stretching, fixing treatment, drying, and heat treatment.

That is, the PVA film was immersed in water at 30 ° C for 30 seconds of preliminary swelling, and then immersed in an aqueous solution (dyeing bath) having an iodine concentration of 0.4 g/L and a potassium iodide concentration of 40 g/L at 35 ° C for 3 minutes for dyeing. Next, uniaxial stretching was carried out in an aqueous solution (stretching bath) having a boric acid concentration of 4% at 50 ° C in a longitudinal direction at a draw ratio of 5 times, further at a potassium iodide concentration of 40 g/L, a boric acid concentration of 40 g/L, and zinc chloride. The aqueous solution (fixed treatment bath) having a concentration of 10 g/L at 30 ° C was immersed for 5 minutes for fixation treatment. Then, the film was subjected to hot air drying at 40 ° C, and further heat treatment was performed at 100 ° C for 5 minutes.

A test piece having a length of 50 cm and a width of 25 cm was obtained from any position of the obtained polarizing film. In addition, a polarizing plate of 50 cm × 50 cm having a small defect was prepared, and the above test pieces were stacked on the polarizing plate such that the orientation axis was perpendicular thereto, and this was placed on an X-ray film illumination box for X-ray photograph observation to confirm Defects in each test piece. Further, when there is no defect in the test piece, the overlapping polarizing plate/test piece appears completely black, and when a defect occurs in the test piece, a point-like significant defect can be recognized by the portion of the light leakage. It was observed that two or more test pieces of the obvious defects were unacceptable, and the yield of the test pieces of 20 pieces was determined.

[Evaluation of polarized film (100 pieces of test)]

Except that the number of test pieces was changed from 20 pieces to 100 pieces, except for the test pieces in which one or more obvious defects were observed to be unsatisfactory, the above 20 pieces of test pieces were subjected to the same operation, and the pass rate in 100 pieces of test pieces was determined. .

[Immunity of polarized film and evaluation of foreign matter]

A test piece having a length of 50 cm and a width of 25 cm was obtained from any position of the obtained polarizing film. Further, a polarizing plate of 50 cm × 50 cm in which uneven dyeing and foreign matter are small is prepared, and the test piece is stacked on the polarizing plate such that the orientation axis is perpendicular, and this is placed in an X-ray film illumination box for X-ray photograph observation. In the above, the unevenness of the dye and the foreign matter in the test piece were evaluated on the basis of the following criteria.

‧ uneven dyeing

Grade A: No uneven dyeing was observed

Grade B: Only some micro-staining is uneven, but it is a level of no problem in use.

Grade C: There is uneven dyeing that becomes a problem in use.

‧foreign matter

Grade A: No foreign matter observed

B grade: only a few foreign objects, but the level of no problem

Class C: A foreign object that has become a problem in use.

[Modulation Example 1]

"Modulation of the drum 1"

After the surface of the drum (peripheral surface) of the drum made of carbon steel having a width of 1.0 m is subjected to preliminary treatment such as buffing and degreasing treatment, a chrome plating bath is used on the surface of the drum, and chrome plating is performed under the following conditions. . Moreover, it is made to be 200 g/L of chromic anhydride and sulfuric acid at a concentration based on the use of a drug. In the form of 2 g/L, these drugs are dissolved in distilled water to form a chrome plating bath.

‧ chrome bath temperature: 55 ° C

‧ Current density: 20A/dm ²

‧ chrome layer thickness (after grinding): 50μm

Then, after the chrome plating treatment was completed, the film forming drum was heat-treated at 102 ° C for 50 hours and allowed to cool.

The film forming drum for forming a chromium plating layer on the surface (peripheral surface) by the above-described chrome plating treatment and heat treatment was 760 HV as measured by the above method. Hereinafter, the film forming drum is referred to as "drum 1".

[Modulation Example 2]

"Modulation of the drum 2"

A chrome-plating treatment and a heat treatment were carried out in the same manner as in Preparation Example 1 except that the chrome plating bath temperature was changed to 52 ° C, and a film forming rotor for forming a chrome plating layer on the surface (circumferential surface) was prepared. With respect to the film forming drum, the surface hardness was measured by the above method to be 840 HV. Hereinafter, the film forming drum is referred to as "drum 2".

[Modulation Example 3]

"Modulation of the drum 3"

In the same manner as in Preparation Example 1, except for changing the temperature of the chrome plating bath to 48 ° C, chrome plating treatment and heat treatment were carried out to prepare a film forming drum for forming a chromium plating layer on the surface (peripheral surface). The surface hardness of the roll for film formation was 950 HV as measured by the above method. Hereinafter, the film forming drum is referred to as "drum 3".

[Modulation Example 4]

"Modulation of the drum 4"

In the same manner as in Preparation Example 1, except for changing the temperature of the chrome plating bath to 67 ° C, chrome plating treatment and heat treatment were carried out to prepare a film forming drum for forming a chromium plating layer on the surface (peripheral surface). The surface hardness of the roll for film formation was 525 HV as measured by the above method. Hereinafter, the film forming drum is referred to as "drum 4".

[Example 1]

The drum 1 is installed in a casting film forming apparatus and connected to a warm water circulation device. Next, the circumferential surface of the drum 1 is polished. The number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.10 / mm ² as measured by the above method. Thereafter, the surface temperature of the drum 1 was raised by a warm water circulation device at a temperature change rate of 1 ° C / hour, and the surface temperature was maintained at 90 ° C. The maximum temperature gradient at this time is 3.8 ° C / m.

Further, 100 parts by mass of a PVA having a degree of saponification of 99.9 mol% and a degree of polymerization of 2,400 (a saponified product of a homopolymer of vinyl acetate) was immersed in 2,500 parts by mass of distilled water at 35 ° C for 24 hours, and then subjected to centrifugal dehydration. PVA water-containing tablets. The volatile matter content in the PVA aqueous pellet was 70% by mass. 333 parts by mass of the PVA water-containing pellets (100 parts by mass in terms of PVA in a dry state), and 12 parts by mass of glycerin and 0.3 parts by mass of a surfactant (containing 95% by mass of lauric acid diethanolamine) are added, and then fully mixed. The mixture was heated and melted at a maximum temperature of 130 ° C in a vented two-axis extruder. The obtained PVA in a molten state was cooled to 100 ° C by a heat exchanger, and then extruded on a drum 1 having a surface temperature of 90 ° C by a hanger mold of 900 mm width, and further dried in a hot air drying furnace. Drying, by cutting both ends (side portions) in the width direction, an elongated PVA film having a width of 0.7 m was continuously produced. Moreover, the film forming speed was 8 m/min. The film-formed PVA film (thickness: 60 μm, length: 8,000 m) was a continuous roll of a cylindrical core made of aluminum having a diameter of 6 Å to form a film roll.

Using the obtained film roll, after the measurement of the number of defects of the PVA film and the evaluation of the polarizing film (20 pieces of test) by the above method, the number of defects A in the winding start portion was 0.102 / m ² (wherein the rotation period) The disadvantage is 0.031 / m ² ), the pass rate of the polarizing film produced by the PVA film on the winding start side is 100%, and the number of defects A in the winding end is 0.098 / m. ² (in which the rotation cycle defect was 0.029 pieces/m ² ), and the pass rate of the polarizing film produced by the PVA film on the winding start portion side was 100%. The number of the defects A in the winding end portion was calculated to be 0.96 times with respect to the number of the defects A in the winding start portion.

[Embodiment 2]

A PVA film was continuously produced into a film roll in the same manner as in Example 1 except that the length of the PVA film was changed from 8,000 m to 3,000 m. Further, the number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.11 / mm ² as measured by the above method.

Using the obtained film roll, after the measurement of the number of defects of the PVA film and the evaluation of the polarizing film (20 pieces of test) by the above method, the number of defects A in the winding start portion was 0.110 / m ² (wherein the rotation period) The disadvantage is 0.044 / m ² ), the pass rate of the polarizing film produced by the PVA film on the winding start side is 100%, and the number of defects A in the winding end is 0.121 / m. ² (in which the rotation cycle defect was 0.036 / m ² ), and the pass rate of the polarizing film produced by the PVA film on the winding start portion side was 100%. The number of the defects A in the winding end portion was calculated to be 1.10 times with respect to the number of the defects A in the winding start portion.

[Reference Example 1]

A PVA film was continuously produced into a film roll in the same manner as in Example 1 except that the length of the PVA film was changed from 8,000 m to 15,000 m. Further, the number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.10 / mm ² as measured by the above method.

After the obtained film roll was used, the number of defects A of the PVA film was measured by the above method, and the number of defects A in the winding start portion was 0.108 pieces/m ² (wherein the rotation cycle defect was 0.032 pieces/m ² ), and the roll was used. The number of defects A in the winding end portion is 0.160 pieces/m ² (wherein the rotation period defect is 0.096 pieces/m ² ), and the number of defects A in the winding start portion is the disadvantage A in the winding end portion. The number is calculated to be 1.48 times.

[Example 3]

A PVA film was continuously produced into a film roll in the same manner as in Example 1 except that the degree of polymerization of PVA was changed from 2,400 to 3,300, and the length of the PVA film was changed from 8,000 m to 15,000 m. Further, the number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.10 / mm ² as measured by the above method.

Using the obtained film roll, after measuring the number of defects of the PVA film and the evaluation of the polarizing film (100 pieces of test) by the above method, the number of defects A in the winding start portion was 0.088 / m ² (wherein the rotation period) The disadvantage is 0.018 pieces/m ² ), the pass rate of the polarizing film produced from the PVA film on the winding start side is 98%, and the number of defects A in the winding end is 0.118 / m. ² (in which the rotation cycle defect was 0.024 / m ² ), and the pass rate of the polarizing film produced by the PVA film on the winding start portion side was 95%. The number of the defects A in the winding end portion was calculated to be 1.34 times with respect to the number of the defects A in the winding start portion.

[Example 4]

A PVA film was continuously produced into a film roll in the same manner as in Example 1 except that the degree of polymerization of PVA was changed from 2,400 to 6,000, and the length of the PVA film was changed from 8,000 m to 15,000 m. Further, the number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.13 / mm ² as measured by the above method.

Using the obtained film roll, after measuring the number of defects of the PVA film and the evaluation of the polarizing film (100 pieces of test) by the above method, the number of defects A in the winding start portion was 0.067 / m ² (wherein, the rotation period) The disadvantage is 0.007/m ² ), the pass rate of the polarizing film produced from the PVA film on the winding start side is 99%, and the number of defects A in the winding end is 0.074/m. ² (in which the rotation cycle defect was 0.007 / m ² ), and the pass rate of the polarizing film produced by the PVA film on the winding start portion side was 99%. The number of the defects A in the winding end portion was calculated to be 1.10 times with respect to the number of the defects A in the winding start portion.

[Example 5]

A PVA film was continuously produced into a film roll in the same manner as in Example 1, except that the drum 2 was used instead of the drum 1, and the length of the PVA film was changed from 8,000 m to 3,000 m. Further, the number of cracks in the surface (peripheral surface) of the drum 2 after polishing and polishing of 200 μm ² or more was 0.39 pieces/mm ² as measured by the above method.

Using the obtained film roll, after the measurement of the number of defects of the PVA film and the evaluation of the polarizing film (20 pieces of test) by the above method, the number of defects A in the winding start portion was 0.172 / m ² (wherein the rotation period) The disadvantage is 0.052 pieces/m ² ), the pass rate of the polarizing film produced from the PVA film on the winding start side is 90%, and the number of defects A in the winding end is 0.224 / m. ² (in which the rotation cycle defect was 0.134 / m ² ), and the yield of the polarizing film produced by the PVA film on the winding start portion side was 85%. The number of the defects A in the winding end portion was calculated to be 1.30 times with respect to the number of the defects A in the winding start portion.

[Embodiment 6]

The PVA film was continuously produced into a film roll in the same manner as in Example 1 except that the surface temperature of the drum 1 was changed from 90 ° C to 110 ° C and the length of the PVA film was changed from 8,000 m to 3,000 m. Further, the number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.13 / mm ² as measured by the above method.

Using the obtained film roll, after measuring the number of defects of the PVA film and the evaluation of the polarizing film (20 pieces of test) by the above method, the number of defects A in the winding start portion was 0.132 / m ² (wherein the rotation period) The disadvantage is 0.053 pieces/m ² ), the pass rate of the polarizing film produced from the PVA film on the winding start side is 95%, and the number of defects A in the winding end is 0.180 / m. ² (in which the rotation cycle defect was 0.090 pieces/m ² ), and the pass rate of the polarizing film produced by the PVA film on the winding start portion side was 90%. The number of the defects A in the winding end portion was calculated to be 1.36 times with respect to the number of the defects A in the winding start portion.

[Embodiment 7]

A PVA film was continuously produced into a film roll in the same manner as in Example 1 except that the temperature change rate was changed from 1 ° C / hour to 5 ° C / hour. Further, the number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.10 / mm ² as measured by the above method.

After the obtained film roll was used, the number of defects of the PVA film was measured by the above method, and the number of defects A in the winding start portion was 0.110 / m ² (wherein the rotation cycle defect was 0.044 / m ² ), and the roll was used. The number of defects A in the winding end portion was 0.122 / m ² (wherein the rotation period defect was 0.049 / m ² ). The number of the defects A in the winding end portion was calculated to be 1.11 times with respect to the number of the defects A in the winding start portion.

[Comparative Example 1]

A PVA film was continuously produced to form a film roll in the same manner as in Example 1, except that the drum 3 was used instead of the drum 1. Further, the number of cracks in the surface (peripheral surface) of the drum 3 after polishing and polishing of 200 μm ² or more was 0.73 pieces/mm ² as measured by the above method.

Using the obtained film roll, the number of defects of the PVA film and the evaluation of the polarizing film (20 pieces of test) were carried out by the above method, and the number of defects A in the winding start portion was 0.291 / m ² (wherein the rotation period) The disadvantage is 0.175/m ² ), the pass rate of the polarizing film produced by the PVA film on the winding start side is 80%, and the number of defects A in the winding end is 0.938 / m. ² (in which the rotation cycle defect was 0.750 pieces/m ² ), and the pass rate of the polarizing film produced by the PVA film on the winding start portion side was 50%. The number of the defects A in the winding end portion was calculated to be 3.22 times with respect to the number of the defects A in the winding start portion.

[Comparative Example 2]

A PVA film was continuously produced into a film roll in the same manner as in Example 1 except that the surface temperature of the drum 1 was changed from 90 ° C to 120 ° C and the length of the PVA film was changed from 8,000 m to 3,000 m. Further, the number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.11 / mm ² as measured by the above method.

Using the obtained film roll, the number of defects of the PVA film and the evaluation of the polarizing film (20 pieces of test) were carried out by the above method, and the number of defects A in the winding start portion was 0.252 / m ² (wherein the rotation period) The disadvantage is 0.101 / m ² ), the pass rate of the polarizing film produced by the PVA film on the winding start side is 80%, and the number of defects A in the winding end is 0.358 / m ² (in which the rotation cycle defect was 0.251 / m ² ), and the yield of the polarizing film produced by the PVA film on the winding start portion side was 65%. The number of the defects A in the winding end portion was calculated to be 1.42 times with respect to the number of the defects A in the winding start portion.

[Comparative Example 3]

In the first embodiment, although the surface temperature of the drum 1 was changed from 90 ° C to 40 ° C to produce a PVA film, it was difficult to dry on the drum. The film was peeled off from the drum, and thus each evaluation could not be performed.

[Comparative Example 4]

A PVA film was continuously produced into a film roll in the same manner as in Comparative Example 1, except that the temperature change rate was changed from 1 ° C / hour to 5 ° C / hour. Further, the number of cracks in the surface (peripheral surface) of the drum 3 after polishing and polishing of 200 μm ² or more was 0.73 pieces/mm ² as measured by the above method.

Using the obtained film roll, after measuring the number of defects of the PVA film by the above method, the number of defects A in the winding start portion was 0.332 / m ² (wherein the rotation cycle defect was 0.166 / m ² ), The number of defects A in the winding end portion was 1.349 pieces/m ² (wherein the rotation period defect was 1.214 pieces/m ² ). The number of the defects A in the winding end portion was calculated to be 4.06 times with respect to the number of the defects A in the winding start portion.

[Embodiment 8]

The drum 1 is installed in a casting film forming apparatus and connected to a warm water circulation device. Next, the circumferential surface of the drum 1 is polished. The number of cracks in the surface (peripheral surface) of the drum 1 after polishing and polishing of 200 μm ² or more was 0.10 / mm ² as measured by the above method. Thereafter, the surface temperature of the drum 1 was raised by the warm water circulation device, and the surface temperature was maintained at 90 °C.

Further, 100 parts by mass of a PVA having a degree of saponification of 99.9 mol% and a degree of polymerization of 2,400 (a saponified product of a homopolymer of vinyl acetate) was immersed in 2,500 parts by mass of distilled water at 35 ° C for 24 hours, and then subjected to centrifugal dehydration. PVA water-containing tablets. The volatile matter content in the PVA aqueous pellet was 70% by mass. 333 parts by mass of the PVA water-containing pellets (100 parts by mass in terms of dry state PVA), and after adding 12 parts by mass of glycerin and 0.3 parts by mass of a surfactant (containing 95% by mass of lauric acid diethanolamine), they are sufficiently mixed. For the mixture, this was heated and melted at a maximum temperature of 130 ° C in a vented two-axis extruder. The obtained PVA in a molten state was cooled to 100 ° C by a heat exchanger, and then extruded on a drum 1 having a surface temperature of 90 ° C by a hanger mold of 900 mm width, and further dried in a hot air drying oven. An elongated PVA film having a width of 0.7 m was continuously produced by trimming both end portions (side portions) in the width direction. Moreover, the film forming speed was 8 m/min. The PVA film (thickness: 60 μm, length: 12,000 m) after film stabilization was a continuous winding of a cylindrical core made of aluminum having a diameter of 6 Å to form a film roll.

The wrinkles of the obtained film roll (wrinkles generated when the PVA film was wound) were rated as A when evaluated by the above method. Further, when the root mean square roughness of the PVA film was measured by the above method using the PVA film rolled up from the obtained film roll, the root mean square roughness in the surface on the side where the surface of the drum 1 was in contact was 4.1 nm. The root mean square roughness in the other side was 1.9 nm. The difference between the two is calculated to be 2.2 nm.

The PVA film which was taken up by the film roll was sequentially subjected to preliminary swelling, dyeing, ‧ fixed treatment, uniaxial stretching, cleaning, and drying to carry out continuous treatment to prepare a polarizing film. That is, the PVA film was immersed in water at 30 ° C for 60 seconds to prepare for swelling, and then immersed in an aqueous solution (dyeing bath) having an iodine concentration of 0.4 g/L and a potassium iodide concentration of 40 g/L at 35 ° C for 110 seconds for dyeing. Subsequently, it was immersed in an aqueous solution (fixed treatment bath) having a boric acid concentration of 30 g/L at 30 ° C for 90 seconds for fixation treatment, and further stretched in the longitudinal direction in an aqueous solution (stretching bath) having a boric acid concentration of 4% at 50 ° C. Uniaxial stretching was performed at a magnification of 5 times. Then, it was immersed in an aqueous solution (cleaning bath) having a boric acid concentration of 15 g/L at 30 ° C for 10 seconds, washed, and dried by hot air at 55 ° C to prepare a polarizing film. Moreover, in the final treatment bath before entering the drying step, The angle between the liquid surface of the cleaning bath and the film surface when taken out from the cleaning bath is set to 60° by changing the position of the guide roller, and the upper side of the film at this time is used as the PVA. A face having a smaller root mean square roughness in the film.

When the dyeing unevenness of the obtained polarizing film was evaluated by the above method, it was A grade. Further, when the foreign matter of the obtained polarizing film was evaluated by the above method, it was Grade A.

[Embodiment 9]

A PVA film was continuously produced in the same manner as in Example 8 except that the drum 2 was used instead of the drum 1, and a film roll was produced. Further, the number of cracks in the surface (peripheral surface) of the drum 2 after polishing and polishing of 200 μm ² or more was 0.37 / mm ² as measured by the above method.

The wrinkles of the obtained film roll (wrinkles generated when the PVA film was wound) were rated B as described above. Further, when the root mean square roughness of the PVA film was measured by the above method using the PVA film rolled up from the obtained film roll, the root mean square roughness in the surface on the side where the surface of the drum 2 was in contact was 6.7 nm. The root mean square roughness in the other side was 2.0 nm. The difference between the two is calculated to be 4.7 nm.

A polarizing film was produced in the same manner as in Example 8 with respect to the PVA film wound up from the film roll. When the uneven dyeing of the obtained polarizing film was evaluated by the above method, it was B grade. Further, when the foreign matter of the obtained polarizing film was evaluated by the above method, it was B grade.

[Comparative Example 5]

A PVA film was continuously produced in the same manner as in Example 8 except that the drum 3 was used instead of the drum 1, and a film roll was produced. Further, the number of cracks in the surface (peripheral surface) of the drum 3 after polishing and polishing of 200 μm ² or more was 0.73 pieces/mm ² as measured by the above method.

The wrinkles of the obtained film roll (wrinkles generated when the PVA film was wound) were rated as A when evaluated by the above method. Further, when the root mean square roughness of the PVA film was measured by the above method using the PVA film rolled up from the obtained film roll, the root mean square roughness in the surface on the side where the surface of the drum 3 was in contact was 28.3 nm. The root mean square roughness in the other side was 2.6 nm. The difference between the two is calculated to be 25.7 nm.

A polarizing film was produced in the same manner as in Example 8 with respect to the PVA film wound up from the film roll. When the uneven dyeing of the obtained polarizing film was evaluated by the above method, it was C grade. Further, when the foreign matter of the obtained polarizing film was evaluated by the above method, it was C grade.

[Comparative Example 6]

A PVA film was continuously produced in the same manner as in Example 8 except that the drum 4 was used instead of the drum 1, and a film roll was produced. Further, the number of cracks in the surface (peripheral surface) of the drum 4 after polishing and polishing of 200 μm ² or more was 0.15 pieces/mm ² as measured by the above method.

The wrinkles of the obtained film roll (wrinkles generated when the PVA film was wound) were evaluated as C grade according to the above method. Further, when the root mean square roughness of the PVA film was measured by the above method using the PVA film rolled up from the obtained film roll, the root mean square roughness in the surface on the side where the surface of the drum 4 was in contact was 2.8 nm. The root mean square roughness in the other side was 2.6 nm. The difference between the two was calculated to be 0.2 nm.

A polarizing film was produced in the same manner as in Example 8 with respect to the PVA film wound up from the film roll. The uneven dyeing of the obtained polarizing film When the above method is evaluated, it is grade A. Further, when the foreign matter of the obtained polarizing film was evaluated by the above method, it was Grade A.

[Embodiment 10]

The film roll obtained in Example 8 was used to produce a polarizing film in the same manner as in Example 8 except that the angle between the bath surface of the cleaning bath and the film surface when the cleaning bath was taken out was changed from 60° to 45°. When the dyeing unevenness of the obtained polarizing film was evaluated by the above method, it was A grade. Further, when the foreign matter of the obtained polarizing film was evaluated by the above method, it was B grade.

[Comparative Example 7]

Using the film roll obtained in Example 8, except that the surface on the upper side of the film when taken out from the cleaning bath was changed to the surface having a large root mean square roughness in the PVA film to be used, a polarizing film was produced in the same manner as in Example 8. . When the dyeing unevenness of the obtained polarizing film was evaluated by the above method, it was A grade. Further, when the foreign matter of the obtained polarizing film was evaluated by the above method, it was C grade.

[Comparative Example 8]

Using the film roll obtained in Example 8, a polarizing film was produced in the same manner as in Example 8 except that the angle between the liquid surface of the cleaning bath and the film surface when the cleaning bath was taken out was changed from 60° to 25°. When the dyeing unevenness of the obtained polarizing film was evaluated by the above method, it was A grade. Further, when the foreign matter of the obtained polarizing film was evaluated by the above method, it was C grade.

[Comparative Example 9]

The film roll obtained in Example 8 was used to produce a polarizing film in the same manner as in Example 8 except that the angle between the liquid surface of the cleaning bath and the film surface when the cleaning bath was taken out from the cleaning bath was changed from 60° to 88°. Dyeing the obtained polarizing film When the color unevenness is evaluated according to the above method, it is grade A. Further, when the foreign matter of the obtained polarizing film was evaluated by the above method, it was C grade.

Claims (12)

A method for producing a polyvinyl alcohol-based polymer film, comprising: a chrome-plated layer on a surface thereof, a Vickers hardness of 550 HV or more and less than 900 HV, and a surface temperature of 50 ° C or more and 115 ° C or less a step of forming a film by casting and drying a polyvinyl alcohol-based polymer in a solution state or a molten state, and forming a film in a solution state or a molten state before starting the casting of the polyvinyl alcohol-based polymer in the surface of the metal support The area (the product of the maximum width and the maximum end distance) has a number of cracks of 200 μm ² or more of 0.7/mm ² or less. The production method according to the first aspect of the invention, wherein the polyvinyl alcohol-based polymer in a solution state or a molten state comprises a form of a film forming solution of a polyvinyl alcohol-based polymer and water. The production method according to claim 1 or 2, wherein the polyvinyl alcohol-based polymer has a polymerization degree of 3,000 or more and 10,000 or less. The manufacturing method according to claim 1 or 2, wherein the surface hardness of the metal support has a Vickers hardness of 600 HV or more and less than 800 HV. The manufacturing method of claim 1 or 2, wherein the surface temperature of the metal support having a surface having a chrome plating layer and a Vickers hardness of 550 HV or more and less than 900 HV is set to a temperature of 0.5 ° C / hour or more The speed is set to be 50 ° C or more and 115 ° C or less. The manufacturing method according to claim 1 or 2, which is a polyvinyl alcohol-based polymer having a defect area of 400 μm ² or more and a depth of 0.3 μm or more on the surface of the film of 0.25/m ² or less. Film. A method of producing a sixth aspect of the invention, which is a long-form polyvinyl alcohol-based polymer film. The manufacturing method of the seventh aspect of the patent application has a length of 6,000 m or more. The manufacturing method of claim 7, wherein the above disadvantages include the disadvantage that the longitudinal direction of the film is substantially at the same position in the width direction of the film at substantially constant intervals. According to the manufacturing method of the first or second aspect of the patent application, when the root mean square roughness is measured on both sides of the film, the difference between the root mean square roughness of the obtained two groups is 0.3 nm or more and 10 nm or less, which is small. A polyvinyl alcohol-based polymer film having a root mean square roughness of 10 nm or less. The manufacturing method of claim 10, wherein the larger root mean square roughness is 1 nm or more and 20 nm or less. A manufacturing method according to claim 10, which is a long-form polyvinyl alcohol-based polymer film.