KR102260000B1 - Polyvinyl alcohol-based polymer film - Google Patents

Abstract

[Problem] A polarizing film with few defects, as well as a PVA-based polymer film capable of producing a polarizing plate with good yield, and polarizing with a stable quality with a small difference in surface properties from the winding start portion to the winding end portion of the PVA-based polymer film Provision of the film roll which can manufacture a film further and a polarizing plate.
^{[Solutions] A PVA-based polymer film having an area of 400 µm 2} or more and a depth of 0.3 µm or more as a dent from the film surface is 0.25 pieces/m 2 or less, and a long PVA-based polymer film formed by continuously winding ^{As a film roll, with respect to a defect having an area of 400 µm 2} or more and a depth of 0.3 µm or more as a dent from the film surface, the PVA-based polymer film is wound with respect to the number of defects in the winding start portion of the PVA-based polymer film. The film roll whose number of said faults in the end part is 1.4 times or less.

Description

Polyvinyl alcohol-based polymer film {POLYVINYL ALCOHOL-BASED POLYMER FILM}

The present invention relates to a polyvinyl alcohol-based polymer film useful as a raw film for polarizing film production or the like (hereinafter, “polyvinyl alcohol” may be abbreviated as “PVA”), a method for producing a polarizing film using the same, and a polarizing film, PVA It relates to a film roll in which a polymer film is continuously wound, and a method for producing a PVA polymer film.

PVA-based polymer films are used in various applications by using unique properties related to transparency, optical properties, mechanical strength, water solubility, etc., and in recent years, using their excellent optical properties, a polarizing plate, a basic component of liquid crystal displays (LCD) The use as a manufacturing raw material (raw film) of the polarizing film which comprises , is expanding. In the fields of liquid crystal monitors and liquid crystal televisions, large screens are rapidly increasing, but if the polarizing plate has a defect, it cannot be incorporated into the product and the yield (product yield) is lowered. Therefore, there is a demand for a polarizing plate and a polarizing film with fewer defects than before. is becoming

By the way, with respect to the optical film containing not only a polarizing film but a protective film, retardation film, etc., various techniques are known so far. For example, when a thermoplastic resin such as polyester, polyamide, or polyolefin is heated above its melting point to make a molten polymer, extruded from a nozzle and cooled to produce a film used for optical applications, etc., present in the polymer As a means for solving the problem that oligomers (oligomers) are deposited on the surface during film production and adhere to the surface of the casting drum or roll, resulting in surface defects of the film, the outer peripheral surface has a surface roughness of 1 S or less and chromium atoms on the surface It is known to use the film manufacturing apparatus which uses the drum or roll for film manufacture which has a chromium plating film containing 0.5-5% of carbon atoms as an atom number with respect to this (refer patent document 1). In Patent Document 1, polyethylene terephthalate is melted at 275°C, extruded from a T-die and quenched with a casting drum cooled to 25°C to form an amorphous sheet, and then heated with a plurality of metal rolls arranged downstream of the casting drum. However, when cooling, the use of a roll having a specific chromium plating film as a part of the plurality of metal rolls is specifically described.

In addition, when the polymer resin solution is cast on a support to prepare a film-forming film, a polymer resin film with excellent transparency and surface flatness useful for optical applications by resolving surface defects (protrusion-like defects on the film surface) In order to obtain, it is known that the number per unit area of the fault of the specific size which exists in the support body surface to be used shall be below a specific numerical value (refer patent document 2). In Patent Document 2, a solution formed by dissolving an aromatic polycarbonate resin in a mixed solvent of ethanol and methylene chloride and a support having specific surface properties (mirror polishing plate made of SUS-316) are used, and all of these temperatures are 15° C. It is specifically described that the solution was adjusted to the degree, and the solution was hand-coated on a support and dried to obtain an aromatic polycarbonate film.

In addition, when manufacturing an optical film by a melt-casting film manufacturing method in which a film-like thermoplastic resin (alicyclic structure-containing polymer or cellulose ester, etc.) melt-extruded from an extruder is cooled by a cooling drum, the cooling drum is strongly contaminated with foreign substances As a means for solving the problem of adhesion and appearance of defects called "pressed scratches", an organic solvent is attached to the surface of the cooling drum, and then the surface of the cooling drum is wiped by wiping means and cooled together with the organic solvent It is known to manufacture an optical film by removing the contamination of the drum surface, then attaching a film-like thermoplastic resin melt-extruded from an extruder to the cooling drum surface portion after wiping and cooling it (refer to Patent Document 3). In Patent Document 3, a mixture containing a hydrogenated substance of a norbornene-based ring-opening polymer and a cellulose acetate propionate is melt-extruded, and the film-shaped resin melt is a cooling drum equipped with a specific cleaning means (hardened chrome plating film having a Vickers hardness of 800). A resin sheet is described by adhering to the surface or having an amorphous chromium plating film surface having a Vickers hardness of 1200) and cooling and solidifying it while conveying it.

Japanese Patent Laid-Open No. 9-207210 Japanese Laid-Open Patent Publication No. 2000-84960 Japanese Laid-Open Patent Publication No. 2006-82261 Japanese Patent Publication No. 1-19477 Japanese Laid-Open Patent Publication No. 2005-238833 Japanese Patent Laid-Open No. 9-1568 Japanese Patent Laid-Open No. 2001-315138

However, it has been difficult to manufacture a polarizing film or a polarizing plate with few defects to the level required in recent years by simply adopting the above-described conventional technique. That is, in the method of Patent Document 1, it is necessary to heat the thermoplastic resin above its melting point to form a molten polymer, but the PVA-based polymer is not a thermoplastic resin except for a special modified PVA-based polymer, so such a film forming method It is difficult to employ|adopt for manufacture of a PVA-type polymer film, and even if employ|adopted, the film excellent in surface properties cannot be obtained. In addition, as a film forming method of a PVA-based polymer film, a film-forming undiluted solution in which a PVA-based polymer is dissolved in a liquid medium or a film-forming undiluted solution containing a PVA-based polymer and a liquid medium and a PVA-based polymer is melted is used. Although a method of forming a film by casting and drying on a support is known, the method is different from the method of forming a film by cooling a molten polymer substantially free of a liquid medium as described in Patent Document 1 on a casting drum. Since it is greatly different, if the drum for film production described in Patent Document 1 is simply used, using the above film-forming stock solution, it is cast and dried on the drum for film production, and even if a PVA-based polymer film is formed into a film, The fine defects caused by minute cracks existing on the surface of the chrome-plated film of the film production drum cannot be sufficiently controlled, and the polarizing plate or polarizing film produced using the obtained PVA-based polymer film sufficiently achieves the quality level required recently. Can not.

On the other hand, Patent Document 2 relates to a film production method in which a solution containing a polymer resin and a solvent as main components is cast on a support and then dried to remove the solvent. Although the method of Patent Document 2 is simply adopted, it is applied to the film surface. Even if the protrusion-like defects could be eliminated, the dents from the film surface could not be sufficiently controlled, and the polarizing plate or polarizing film produced using the obtained PVA-based polymer film could sufficiently achieve the quality level required recently. can't

In addition, since the method of Patent Document 3 is to cool the melt of the thermoplastic resin with a cooling drum similarly to the method of Patent Document 1, it is difficult to employ the method of Patent Document 3 for production of a PVA-based polymer film, and although Even if it was employable, a film excellent in surface properties could not be obtained. In addition, if the wiping means described in Patent Document 3 is simply adopted, 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 in which the PVA-based polymer is melted is used. , even if this was cast and dried on a metal support to form a film of a PVA-based polymer film, the defects in the concave state could not be sufficiently controlled, rather, scratches on the surface of the metal support by contacting the wiping means to the surface of the metal support. There is also a possibility that the defect of the PVA polymer film obtained may be deteriorated rather than the surface properties of the resulting PVA-based polymer film.

Under the above circumstances, an object of the present invention is to provide a PVA-based polymer film capable of producing a polarizing film with few defects and also a polarizing plate with good yield. In addition, the present invention is a film roll in which a long PVA-based polymer film is continuously wound, and the difference in surface properties from the winding start part to the winding end part of the PVA-based polymer film is small, so that a polarizing film and a polarizing plate with stable quality can be manufactured. It aims to provide a film roll.

In addition, 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 for reasons such as ease of storage and transport and continuous use, but in such a film roll, Wrinkles are likely to occur in the film due to poor slip properties between the films, and such wrinkles are likely to cause deterioration of the quality of the polarizing film to be manufactured. On the other hand, it may be calculated|required by a polarizing film to reduce the dyeing unevenness different from an above-described defect. So, as another aspect, the present invention provides a PVA-based polymer film capable of easily producing a polarizing film with reduced staining unevenness and less wrinkling in the film roll, and a film roll in which it is continuously wound. aim to

In addition, in the case of manufacturing a polarizing film using a PVA-based polymer film as a raw film, dyeing, uniaxial stretching, fixing treatment, etc. are usually performed on the PVA-based polymer film, but when uniaxial stretching is performed in a dry method In the dyeing process or the fixing treatment process, in the case of wet uniaxial stretching, in addition to these processes, in the swelling process before uniaxial stretching or the uniaxial stretching process, a part of the PVA-based polymer is added to the treatment bath to be used. It may elute, and the eluted PVA-type polymer may precipitate in a treatment bath and adhere to a film, or it may precipitate on a film, and may remain as a foreign material in the polarizing film obtained, reducing the quality and yield. Then, this invention aims at providing the manufacturing method of the polarizing film for manufacturing a polarizing film with few such foreign substances, and the polarizing film with few foreign substances manufactured by it.

Another object of the present invention is to provide a method for producing a PVA-based polymer film capable of easily producing the above-described PVA-based polymer film or film roll.

As a result of repeated studies to achieve the above object, the present inventors have made a film of a PVA-based polymer film by casting and drying a PVA-based polymer in a solution state or a molten state on the surface of a metal support such as a drum or a belt. In a PVA-based polymer film with a large number of defects dented from the film surface, such as foreign matter thought to be a resin deposit adhered to a very part of the countless cracks existing on the surface of the metal support, and the convex shape is transferred to the film. This, and such a PVA-based polymer film, has many defects in the polarizing film or polarizing plate produced therefrom, and cannot sufficiently achieve the quality level required in recent years, or leads to a decrease in the yield of the polarizing film or polarizing plate. I found out that there is a problem.

And, if a metal support having a chrome plating layer on the surface and having a surface hardness in a specific range is used, by a general treatment performed on the surface of the metal support before the start of film production, such as buffing, it is present on the surface of the metal support. The number of cracks can be easily reduced, the number of defects dented from the film surface of the obtained PVA-based polymer film can be reduced than before, and when such a PVA-based polymer film is used as a raw film for polarizing film production, It was found that a polarizing film or a polarizing plate satisfying the quality level required in recent years with few defects could be manufactured with good yield.

Further, in addition to the above findings, if a metal support having a chrome plating layer on the surface and a surface hardness in a specific range is used, even if a PVA-based polymer film is continuously formed over a long period of time, variations in the number of dents from the film surface can be maintained at a lower level than before, for example, when producing a film roll in which a long PVA-based polymer film is continuously wound, the surface properties of the PVA-based polymer film from the winding start portion to the winding end portion It discovered that a difference could be made small and the film roll which could manufacture the polarizing film with stable quality further, and a polarizing plate was obtained easily.

In addition, if a metal support having a chrome plating layer on the surface and having a surface hardness in a specific range is used, a PVA-based polymer film having the surface properties of both surfaces of the film within a specific range can be easily obtained, and the PVA-based polymer film is In the film roll which is wound up continuously, wrinkles do not easily generate|occur|produce and the quality deterioration of a polarizing film can be suppressed, Furthermore, according to the said PVA-type polymer film, a polarizing film with reduced dyeing unevenness is easily obtained, and the said PVA-type polymer film. When a polarizing film was manufactured by the specific method using a polymer film, it discovered that the polarizing film with few foreign substances was obtained easily.

The inventors of the present invention completed the present invention by repeating further studies based on such knowledge.

That is, the present invention is

^{[1] A PVA-based polymer film having an area of 400 µm 2} or more and a depth of 0.3 µm or more as defects dented from the film surface of 0.25 pieces/m 2 or less (hereinafter, this PVA-based polymer film is referred to as “PVA-based polymer film (1 )” is sometimes called) ;

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

[3] The PVA-based polymer film according to the above [1] or [2], wherein the polymerization degree 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 the above [1] to [3], which is a long PVA-based polymer film;

[5] The PVA-based polymer film of the above [4] having a length of 6,000 m or more;

[6] The PVA-based polymer film of [4] or [5] above, wherein the defects are at substantially constant intervals in the longitudinal direction of the film and are present at substantially the same positions in the width direction of the film;

[7] A film roll in which a long PVA-based polymer film is continuously wound, ^{with respect to a defect in which an area is 400 µm 2} or more and a depth of 0.3 µm or more as a dent from the film surface, the winding start portion of the PVA-based polymer film a film roll in which the number of the defects in the winding end portion of the PVA-based polymer film is 1.4 times or less with respect to the number of the defects in the film roll (hereinafter, this film roll is sometimes referred to as “film roll (1)”);

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

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

[10] The film roll according to any one of [7] to [9], wherein the polymerization degree 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 according to any one of [7] to [10], wherein the length of the PVA-based polymer film is 6,000 m or more;

[12] the film roll according to any one of [7] to [11], wherein the defects are substantially constant in the longitudinal direction of the film and include the defects present at substantially the same position in the width direction of the film;

[13] When the mean square roughness is measured on each of both surfaces of the film, the difference between the two obtained square mean roughness is 0.3 nm or more and 10 nm or less, and the smaller one is a PVA-based polymer film having a square average roughness of 10 nm or less (hereinafter , This PVA-type polymer film may be called "PVA-type polymer film (2)");

[14] The PVA-based polymer film according to [13], wherein the larger mean square roughness is 1 nm or more and 20 nm or less;

[15] The PVA-based polymer film according to the above [13] or [14], which is a long PVA-based polymer film;

[16] a film roll in which the PVA-based polymer film of the above [15] is continuously wound (hereinafter, this film roll may be referred to as “film roll (2)”);

[17] A method for producing a polarizing film using the PVA-based polymer film according to any one of [13] to [15] as a raw film, comprising a dyeing step, a uniaxial stretching step, a fixing treatment step and a drying step, and drying When leaving the last treatment bath before entering the process, the angle between the liquid level of the treatment bath and the film surface is 30° or more and 85° or less, and the surface on the upper side of the film is the smaller of the polyvinyl alcohol-based polymer film. A manufacturing method that is a surface having a mean square roughness;

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

[19] On the surface of a metal support having a chromium plating layer on the surface, the surface hardness is 550 HV or more and less than 900 HV in Vickers hardness, and the surface temperature is 50 ° C. or more and 115 ° C. or less, a PVA-based polymer in a solution state or a molten state A method for producing a PVA-based polymer film having a step of casting and drying to form a film, wherein the area on the surface of a metal support (between the maximum width and the maximum end) immediately before starting to cast the PVA-based polymer in a solution or molten state. The manufacturing method whose number of cracks whose product of distance) is 200 micrometers 2 or more is 0.7 pieces/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 is in the form of a film-forming stock solution containing the PVA-based polymer and water;

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

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

[23] The above [19] having a chrome plating layer on the surface, and having a step of setting the surface temperature of the metal support having a surface hardness of 550 HV or more and less than 900 HV to 50°C or more and 115°C or less at an alternate temperature rate of 0.5°C/hour or more in terms of Vickers hardness. ] to [22], the manufacturing method in any one of;

[24] The production method according to any one of [19] to [23], wherein the PVA-based polymer film according to any one of [1] to [6] and [13] to [15] is produced.

is about

ADVANTAGE OF THE INVENTION According to this invention, the PVA type polymer film which can manufacture a polarizing film with few defects, and also a polarizing plate with favorable yield can be provided. In addition, according to the present invention, as a film roll in which a long PVA-based polymer film is continuously wound, the difference in surface properties from the winding start part to the winding end part of the PVA-based polymer film is small, so that a polarizing film and a polarizing plate with stable quality can be manufactured. A roll of film that can be used can be provided.

Further, according to the present invention, a PVA-based polymer film capable of easily producing a polarizing film with less wrinkling and reduced dyeing unevenness in a film roll, a film roll formed by continuously winding it, and a small amount of foreign matter The manufacturing method of the polarizing film for manufacturing a polarizing film, and the polarizing film with few foreign substances manufactured by it can be provided.

Moreover, according to this invention, the manufacturing method of the PVA type polymer film which can manufacture said PVA type polymer film or a film roll easily can be provided.

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

[PVA-based polymer film (1)]

The PVA-based polymer film (PVA-based polymer film (1)) of the present invention is a defect dented from the film surface, having an area of 400 µm ² or more and a depth of 0.3 µm or more (hereinafter, when this defect is referred to as “defect A”) The number of ) is 0.25 pieces/m2 or less. As a fault which exists in a plastic film, Void (bubble) in a film; So-called fish eye due to mixing and adhesion of foreign substances; Scratches (mostly spherical dents) occurring during film handling; There are drawbacks due to the transfer of the convex shape on the film production apparatus, but the present inventors have excellent effects such as being able to produce a polarizing film or polarizing plate with few defects in good yield by specially controlling the number of the defects A found to appear. This defect A is considered to be one of the causes of the transfer of the convex shape on the above-described film forming apparatus, and in particular, when a PVA-based polymer film is formed using a metal support such as a drum or a belt as described below, It is thought that one of the causes is that the convex shape by the foreign material thought to be resin deposit adhering on a metal support body is transferred to a film. When defects A occur in a long PVA-based polymer film due to such a cause, at least some of the defects A are at substantially constant intervals in the longitudinal direction of the film and plural at substantially the same position in the width direction of the film (e.g. For example 3 or more) tends to be arranged. Here, the substantially constant interval typically corresponds to the length (total circumference) of one round of a metal support such as a drum or belt, but in some cases, corresponds to an integer multiple of the length of one round. there is also In addition, since a plurality of convex shapes due to foreign substances may be formed on the metal support, a plurality of groups of defects A arranged as described above may also exist.

As mentioned above, in the PVA-type polymer film (1) of this invention, the number of fault A needs to be 0.25 piece/m<2> or less. When the number of defects A exceeds 0.25 pieces/m 2 , there are many defects in the polarizing film or polarizing plate produced therefrom, and the quality level required in recent years cannot be sufficiently achieved, or the polarizing film or polarizing plate with many defects is discarded, etc. This leads to a decrease in the yield of these products. From such a viewpoint, the number of defects A is preferably 0.20 pieces/m2 or less, more preferably 0.15 pieces/m2 or less, still more preferably 0.10 pieces/m2 or less, and particularly preferably 0.075 pieces/m2 or less.

On the other hand, although it is not necessarily limited about the lower limit of the number of faults A, In order to reduce the number of faults A extremely, since there exists a concern, such as the cost for installing a film production facility becoming extremely high, the number of faults A is preferably 0.001 pieces/m 2 or more, more preferably 0.003 pieces/m 2 or more, and still more preferably 0.005 pieces/m 2 or more.

Defect A is a defect dented from the film surface and has an area of 400 µm ² or more and a depth of 0.3 µm or more. Here, the defect A should just be dented from either side of the film toward the inside of the film, usually, most of the defect A is dented from the surface in contact with the metal support to be described later used in film production toward the inside of the film. is defeated In addition, the area of the fault A means the area of the opening part of the fault A. In addition, the depth of the fault A is the depth in the direction perpendicular|vertical with respect to the film plane from the opening part of the fault A, and means the depth in the deepest position.

The number of defects A (units/m2) is the area (unit: unit) of the PVA-based polymer film inspected from one end of the target PVA-based polymer film to the defect A, and until ten defects A are found. can be obtained by dividing 10 (pieces) by m 2 ), specifically, it can be obtained by the method described later in Examples. Here, the determination of whether each fault is a fault A can be performed using a non-contact surface shape measuring machine.

Although there is no restriction|limiting in particular in the shape of the PVA-type polymer film (1), When using the said PVA-type polymer film (1) as a raw film for polarizing film manufacture, etc. WHEREIN: A polarizing film can be manufactured continuously with good productivity. etc., it is preferable that it is a long PVA type polymer film.

The length of the long PVA-based polymer film is not particularly limited, and can be appropriately set depending on the use of the PVA-based polymer film (1), etc., and specifically, the length is preferably 1,000 m or more, and more preferably 4,000 m or more. and more preferably 6,000 m or more, particularly preferably 7,000 m or more, and most preferably 8,000 m or more. In particular, according to the manufacturing method of the PVA-type polymer film mentioned later, while being able to reduce the number of faults A of a PVA-type polymer film, even if a PVA-type polymer film is continuously formed into a film over a long period of time, fluctuations in the number of faults A are reduced. Since it can hold|maintain at a low level, even when the said length is longer (for example, 6,000 m or more), the PVA-type polymer film in which the number of faults A was reduced can be obtained simply. And according to such a longer PVA-based polymer film, it becomes possible to stably manufacture a product satisfying the recently required quality level with fewer defects in a continuous production of a polarizing film over a long period of time with good yield, The complexity and time loss accompanying the exchange of the film roll can also be reduced. There is no particular limitation on the upper limit of the length of the long PVA-based polymer film, but if it is too long, the handleability may decrease, such as excessively large weight or roll diameter when used as a film roll, making storage and transportation difficult, etc. 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 long PVA-based polymer film is not particularly limited, and can be, for example, 0.5 m or more, but in view of the recent demand for a wide polarizing film, it is preferably 1 m or more, and more preferably 2 m or more. and more preferably 4 m or more. There is no particular limitation on the upper limit of the width of the long PVA-based polymer film, but if the width is too wide, it tends to be difficult to stretch uniformly in the case of manufacturing a polarizing film with an apparatus that is put into practical use. , the width of the PVA-based polymer film is preferably 7 m or less.

The thickness of the PVA-based polymer film (1) is not particularly limited, and can be appropriately set depending on the use of the PVA-based polymer film, etc., specifically, the thickness is preferably 300 µm or less, more preferably 150 µm or less, 100 It is more preferable that it is micrometer or less. Moreover, in recent years, a thinner polarizing film may be requested|required, From such a viewpoint etc., it is preferable that the thickness of the PVA-type polymer film 1 is 45 micrometers or less, It is more preferable that it is 35 micrometers or less, It is 25 micrometers or less more preferably. Although there is no restriction|limiting in particular in the lower limit of the thickness of the PVA type polymer film (1), It is preferable that it is 3 micrometers or more, and, as for the said thickness, it is more preferable that it is 5 micrometers or more from the point which can manufacture a polarizing film more smoothly.

As the PVA-based polymer constituting the PVA-based polymer film (1), one produced by saponifying a vinyl ester-based polymer obtained by polymerization of a vinyl ester-based monomer can be used. Examples of the vinyl ester-based monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalphosphate, and vinyl versatate. Among these, vinyl acetate is preferable.

The vinyl ester-based polymer is preferably obtained by using only one or two or more vinyl ester-based monomers as a monomer, and more preferably obtained by using only one vinyl ester-based monomer as a monomer, but one or two types of vinyl ester-based monomers A copolymer of the above vinyl ester-based monomer and another monomer copolymerizable therewith may be used.

As another monomer copolymerizable with such a vinyl ester type monomer, For example, ethylene; olefins having 3 to 30 carbon atoms, such as propylene, 1-butene, and isobutene; Acrylic acid or its salt; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or its salt; Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methacrylic acid 2- methacrylic acid esters such as ethylhexyl, dodecyl methacrylate, and octadecyl methacrylate; Acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid or a salt thereof, acrylamidepropyldimethylamine or a salt thereof, N-methylolacrylamide acrylamide derivatives such as amide or a derivative thereof; Meta such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or its salt, methacrylamidepropyldimethylamine or its salt, N-methylolmethacrylamide or its derivative acrylamide derivatives; N-vinylamide, such as N-vinylformamide, N-vinylacetamide, and N-vinylpyrrolidone; Vinyls such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether ether; vinyl cyanide, such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; Maleic acid or its salt, ester, or acid anhydride; Itaconic acid or its salt, ester, or acid anhydride; vinylsilyl compounds such as vinyltrimethoxysilane; Isopropenyl acetate, etc. are mentioned. The vinyl ester-based polymer may have a structural unit derived from one or two or more of these other monomers.

Although there is no restriction|limiting in particular in the ratio of the structural unit derived from the said other monomer which occupies in the said vinyl ester-type polymer, It is preferable that it is 15 mol% or less based on the mole number of all the structural units which comprise the vinyl ester-type polymer, and 5 mol % or less is more preferable.

The degree of polymerization of the PVA-based polymer is not necessarily limited, but is preferably 200 or more, more preferably 300 or more, still more preferably 400 or more, and particularly preferably 200 or more in that the film strength tends to decrease as the polymerization degree decreases. more than 500 In addition, when the degree of polymerization is too high, the viscosity of the aqueous solution or melted PVA polymer increases, and film formation tends to be difficult, so it is preferably 10,000 or less, more preferably 9,000 or less, still more preferably 8,000 or less, particularly Preferably it is 7,000 or less. Here, the polymerization degree of the PVA-based polymer means the average degree of polymerization measured according to the description of JIS K6726-1994, and after resaponifying and purifying the PVA-based polymer, the intrinsic viscosity [η] (unit: : deciliter/g) from the following formula.

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

In addition, when a PVA-based polymer film is produced by the method described later using a PVA-based polymer having a degree of polymerization in the range of 3,000 or more and 10,000 or less, a PVA-based polymer film having a very small number of defects A is obtained, and a PVA-based polymer is obtained. Even if a film is continuously formed into a film over a long period of time, the fluctuation|variation of the number of fault A can be maintained at a lower level, and it is preferable. From such a viewpoint, it is more preferable that it is 4,000 or more, and, as for the polymerization degree of a PVA-type polymer, it is still more preferable that it is 5,000 or more. In addition, the reason why the above effect appears by using the PVA-based polymer having a degree of polymerization within the range 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 the number of cracks present on the surface of the metal support. It is thought that it increases as the PVA-type polymer in a solution state or a molten state enters easily, and it is estimated that this is because when the PVA-type polymer of the said degree of polymerization is used, this entry is suppressed.

There is no particular limitation on the degree of saponification of the PVA-based polymer, and for example, 60 mol% or more of a PVA-based polymer can be used. In the case of using the PVA-based polymer film as a raw film for optical film production, such as a polarizing film, in particular, The degree of saponification of the PVA polymer is preferably 95 mol% or more, more preferably 98 mol% or more, and still more preferably 99 mol% or more. Here, the degree of saponification of the PVA-based polymer refers to the number of moles of a structural unit that can be converted into a vinyl alcohol unit by saponification (typically a vinyl ester-based monomer unit) and a vinyl alcohol unit of the PVA-based polymer relative to the total number of moles of the vinyl alcohol unit. means the ratio (mol%) occupied by the number of moles of The degree of saponification of the PVA polymer can be measured according to the description of JIS K6726-1994.

When producing the PVA-based polymer film (1), one PVA-based polymer may be used alone, and one or two or more different PVA-based polymers in polymerization degree, saponification degree, modification degree, etc. You may use it together. It is preferable that the content rate of the PVA-type polymer in the PVA-type polymer film (1) is 50 mass % or more, It is more preferable that it is 70 mass % or more, It is still more preferable that it is 85 mass % or more.

It is preferable that the PVA-type polymer film (1) contains a plasticizer. When the PVA-type polymer film (1) contains a plasticizer, generation|occurrence|production of the wrinkles at the time of setting it as a film roll can be prevented, or the process passability at the time of secondary processing can be improved. A polyhydric alcohol is preferable as a plasticizer, and, specifically, ethylene glycol, glycerol, diglycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylol propane, etc. are mentioned. These plasticizers may be used individually by 1 type, and may use 2 or more types together. Among these plasticizers, ethylene glycol or glycerin is preferable from the viewpoints of compatibility with the PVA polymer, availability, and the like.

It is preferable that content of the plasticizer in PVA-type polymer film (1) exists in the range of 1-30 mass parts with respect to 100 mass parts of PVA-type polymers, It is more preferable to exist in the range of 3-25 mass parts, 5-20 mass parts It is more preferable to be in the range.

It is preferable that the PVA-type polymer film (1) contains surfactant from viewpoints, such as the improvement of the peelability from the metal support body used for the manufacture, the improvement of the handleability of a PVA-type polymer film, etc. Although there is no restriction|limiting in particular in the kind of surfactant, Anionic or nonionic surfactant can be used preferably.

Examples of the anionic surfactant include carboxylic acid types such as potassium laurate, sulfuric acid ester types such as octyl sulfate, and sulfonic acid types such as dodecylbenzenesulfonate.

As a nonionic surfactant, For example, alkyl ether types, such as polyoxyethylene oleyl ether, alkylphenyl ether types, such as polyoxyethylene octylphenyl ether, alkylester types, such as polyoxyethylene laurate, polyoxy Alkylamine type such as ethylene laurylamino ether, alkylamide type such as polyoxyethylene lauric acid amide, polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether, lauric acid diethanolamide, oleic acid diethanolamide, etc. Allylphenyl ether types, such as an alkanolamide type|mold of and polyoxyalkylene allylphenyl ether, etc. are mentioned.

These surfactants may be used individually by 1 type, and may use 2 or more types together.

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

The PVA-type polymer film (1) may further contain other components other than the above-mentioned PVA-type polymer, a plasticizer, and surfactant as needed. Such other components include, for example, moisture, antioxidants, ultraviolet absorbers, lubricants, colorants, fillers (inorganic particles, starch, etc.), preservatives, mildew inhibitors, and other high molecular compounds other than the above components. .

[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 the winding start portion of the PVA-based polymer film (the PVA-based polymer film starts to be wound as a film roll) The defect A in the winding end portion of the PVA-based polymer film (the film portion when winding is finished using the PVA-based polymer film as a film roll) with respect to the number of the defects A in the film portion when The number is less than 1.4 times. In such a film roll, since the difference in the surface characteristic from the winding start part of a PVA-type polymer film to the winding end part is small, according to the said film roll, it becomes possible to manufacture a polarizing film with stable quality and further a polarizing plate. From such a viewpoint, the number of the defects A in the winding end portion of the PVA-based polymer film relative to the number of the defects A in the winding start portion of the PVA-based polymer film is preferably 1.3 times or less, and 1.2 times or less. It is more preferable, and it is still more preferable that it is 1.1 times or less. In addition, in the film production of a long PVA-based polymer film, since the number of defects A generally tends to increase with time, the PVA-based polymer film with respect to the number of defects A in the winding start portion of the PVA-based polymer film. The number of the defects A in the winding end portion of the polymer film is usually 0.6 times or more in many cases, and the winding start portion of the PVA-based polymer film from the viewpoint of producing a polarizing film and further polarizing plate with stable quality. The number of the defects A in the winding end portion of the PVA-based polymer film relative to the number of the defects A in is preferably 0.7 times or more, more preferably 0.75 times or more, still more preferably 0.8 times or more, It is especially preferable that it is 0.9 times or more.

In the PVA-based polymer film in the film roll (1) of the present invention, the number of defects A per unit area is not particularly limited, but as the number of defects A in the PVA-based polymer film (1) of the present invention, The number satisfies the number, that is, the number of defects A is 0.25 pieces/m2 or less (with respect to the upper limit, preferably 0.20 pieces/m2 or less, more preferably 0.15 pieces/m2 or less, still more preferably 0.10 pieces/m2 or less , particularly preferably 0.075 pieces/m2 or less, with respect to the lower limit, preferably 0.001 pieces/m2 or more, more preferably 0.003 pieces/m2 or more, still more preferably 0.005 pieces/m2 or more), the polarizing film In the case of continuous manufacturing, it is preferable because it becomes possible to stably manufacture a product satisfying the recently required quality level with few defects in good yield over a long period of time. With respect to the number of defects A per unit area, if the above-described number is satisfied in both the winding start portion and the winding end portion of the PVA-based polymer film, the number is satisfied in the entire PVA-based polymer film. can think

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 can be appropriately set according to the use of the PVA-based polymer film, etc., specifically, the length is 1,000 m or more can be done with However, in recent years, in order to reduce the complexity and time loss accompanying the exchange of a film roll in the manufacture of a polarizing film, a PVA-type polymer film longer than the conventional length of about 4,000 m may be requested|required, and such a longer The length of the PVA-based polymer film is preferably 6,000 m or more, more preferably 7,000 m or more, from the viewpoint of stabilizing the quality of the product even if a polarizing film is continuously manufactured over a long period of time using the PVA-based polymer film, More preferably, it is 8,000 m or more. Although there is no particular limitation on the upper limit of the length of the long PVA-based polymer film, if it is too long, handling properties such as weight and roll diameter become excessively large when it is made into a film roll, and handling properties may decrease, making storage and transportation difficult, and further, in 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 from the viewpoint that it tends to be difficult to manufacture a film roll satisfying the regulations. Moreover, if the said length is 14,000 m or less, and also 10,000 m or less, manufacture of the film roll which satisfy|fills the prescription|regulation of this invention becomes easier.

As other structures related to the PVA-based polymer film used in the film roll (1) of the present invention, the same as those described above as the description of the PVA-based polymer film (1) of the present invention, it is duplicated here A description is omitted.

The film roll 1 of the present invention is formed by continuously winding a long PVA-based polymer film, for example, by continuously winding a long PVA-based polymer film around a cylindrical core. When a cylindrical core is used, it is preferable that both ends of the core form protrusions protruding from the end face of the film roll.

There is no restriction|limiting in particular in the kind of said cylindrical core, For example, a metal thing, a plastic thing, a paper thing, a wooden thing, etc. are mentioned. In addition, a composite-type core such as one in which both metal and plastic are used, one in which both metal and paper are used, and one in which both plastic and paper are used can also be used. Among these, in consideration of strength, durability, low dust generation, etc., a metal and/or plastic core is preferable, and a metal core is more preferable because it is not easily affected by abrasion or the like even after repeated use. As said metal, iron, stainless steel, aluminum etc. are mentioned, for example, 1 type of these may be used individually, and 2 or more types may be used together. Moreover, as said plastics, polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate, polyamide, an epoxy resin, a polyurethane, polyurea, a silicone resin, etc. are mentioned, for example, One of these may be used independently and may use 2 or more types together. Moreover, fiber-reinforced plastics (FRP), such as a carbon fiber reinforced plastics, may be sufficient as the said plastics from viewpoints, such as intensity|strength.

[PVA-based polymer film (2)]

The PVA-based polymer film (PVA-based polymer film (2)) of the present invention, when the square average roughness is measured on each of both surfaces of the film, the difference between the two obtained square average roughness is 0.3 nm or more and 10 nm or less, and a small The average square roughness of the side is 10 nm or less. In a conventional film roll in which a PVA-based polymer film is continuously wound, wrinkles are likely to occur in the film due to poor slip properties between the films. However, according to the PVA-based polymer film (2) of the present invention, the occurrence of wrinkles is reduced can do it In addition, in the wrinkles of the film roll, when the PVA-based polymer film is wound, winding occurs due to the stress remaining in the PVA-based polymer film when it is stored in a warehouse or the like after it is once turned into a film roll, and at this time between the films The slip property may be caused by poor, and according to the PVA-based polymer film (2) of the present invention, the former generation of wrinkles can be effectively reduced, but the latter generation of wrinkles can also be reduced. In addition, according to the PVA-type polymer film (2) of this invention, the polarizing film in which the dyeing unevenness different from an above-described defect was reduced can be manufactured easily.

The mean square roughness in the present invention means the root mean square roughness (Rq) described in JIS B0601:2001, and in the roughness curve obtained from the surface of the film, it is obtained by averaging the squares of the deviations from the mean line to the roughness curve. . The average square roughness in each of both surfaces of a PVA-type polymer film can be measured by the method mentioned later in an Example.

In the PVA-type polymer film (2) of this invention, when the mean square roughness is measured in each of both surfaces of a film, it is necessary for the difference of the two obtained square mean roughness to be 0.3 nm or more and 10 nm or less. When the difference between them is 0.3 nm or more, generation|occurrence|production of the wrinkles in a film roll can be reduced effectively. On the other hand, when the difference between them is 10 nm or less, the dyeing nonuniformity in a polarizing film can be reduced effectively. From such a viewpoint, the difference between the two is preferably 0.5 nm or more, more preferably 0.8 nm or more, still more preferably 1.2 nm or more, particularly preferably 1.5 nm or more, most preferably 2 nm or more, and 7 nm or more. It is preferable that it is less than or equal, and it is more preferable that it is 5 nm or less.

Moreover, in the PVA-type polymer film (2) of this invention, the mean square roughness of the smaller one needs to be 10 nm or less. When the smaller square mean roughness is 10 nm or less, the dyeing unevenness in a polarizing film can be reduced effectively. From such a viewpoint, it is preferable that it is 8 nm or less, as for the smaller square mean roughness, it is more preferable that it is 6 nm or less, It is still more preferable that it is 4 nm or less. In addition, in order to extremely reduce the mean square roughness, it is necessary to perform special processing, and the production cost of the PVA-based polymer film tends to rise, so that the mean square roughness of the smaller one is preferably 0.3 nm or more, and 0.6 nm It is more preferable that it is more than, it is more preferable that it is 0.9 nm or more, It is especially preferable that it is 1.2 nm or more.

In the PVA-based polymer film (2), it is preferable that the larger mean square roughness is 1 nm or more and 20 nm or less. When the larger mean square roughness is 1 nm or more, generation|occurrence|production of the wrinkles in a film roll can be reduced more effectively. On the other hand, when the larger mean square roughness is 20 nm or less, the dyeing unevenness in a polarizing film can be reduced more effectively. From such a viewpoint, the larger mean square roughness is more preferably 2 nm or more, still more preferably 4 nm or more, more preferably 15 nm or less, still more preferably 11 nm or less, and particularly preferably 8 nm or less. Preferably, it is 6 nm or less, most preferably.

Although there is no restriction|limiting in particular in the shape of the PVA-type polymer film (2), When using the said PVA-type polymer film (2) as a raw film for polarizing film manufacture, etc. WHEREIN: A polarizing film can be manufactured continuously with good productivity. etc., it is preferable that it is a long PVA type polymer film.

The length of the long PVA-based polymer film is not particularly limited, and can be appropriately set depending on the use of the PVA-based polymer film (2), etc., and specifically, the length is preferably 1,000 m or more, more preferably 4,000 m or more. and more preferably 6,000 m or more, particularly preferably 7,000 m or more, and most preferably 8,000 m or more. According to such a longer PVA-type polymer film, the complexity and time loss accompanying replacement|exchange of a film roll can be reduced. There is no particular limitation on the upper limit of the length of the long PVA-based polymer film, but if it is too long, the handleability may decrease, such as excessively large weight or roll diameter when used as a film roll, making storage and transportation difficult, etc. is preferably 30,000 m or less, more preferably 25,000 m or less, and still more preferably 20,000 m or less. In addition, one of the causes of wrinkles occurring when the film roll is stored is winding due to the stress remaining in the PVA-based polymer film, but this winding is stronger in the longer and wider PVA-based polymer film. Since it is easy to appear, the effect of this invention appears more notably in a longer PVA-type polymer film.

The width of the long PVA-based polymer film is not particularly limited, and can be, for example, 0.5 m or more, but in view of the recent demand for a wide polarizing film, it is preferably 1 m or more, and more preferably 2 m or more. and more preferably 4 m or more. There is no particular limitation on the upper limit of the width of the long PVA-based polymer film, but if the width is too wide, it tends to be difficult to stretch uniformly in the case of manufacturing a polarizing film with an apparatus that is put into practical use. , the width of the PVA-based polymer film is preferably 7 m or less. In addition, as described for the length of the PVA-based polymer film, since the winding tends to be strong in the longer and wider PVA-based polymer film, the effect of the present invention is more pronounced in the wider PVA-based polymer film. appears conspicuously.

The thickness of the PVA-based polymer film (2) is not particularly limited, and can be appropriately set depending on the use of the PVA-based polymer film, etc., specifically, the thickness is preferably 300 µm or less, more preferably 150 µm or less, 100 It is more preferable that it is micrometer or less. Moreover, in recent years, a thinner polarizing film may be requested|required, and from such a viewpoint, it is preferable that the thickness of the PVA-type polymer film 2 is 45 micrometers or less, It is more preferable that it is 35 micrometers or less, It is 25 micrometers or less more preferably. Although there is no restriction|limiting in particular in the lower limit of the thickness of the PVA-type polymer film (2), It is preferable that it is 3 micrometers or more, and, as for the said thickness, it is more preferable that it is 5 micrometers or more from the point which can manufacture a polarizing film more smoothly. Moreover, since the wrinkles in a film roll are so easy to generate|occur|produce, so that the thickness of a PVA-type polymer film is thinner, the effect of this invention appears more conspicuously in a thinner PVA-type polymer film.

As other structures concerning the PVA-type polymer film (2) of this invention, since it can be set as the thing similar to the above as description of the PVA-type polymer film (1) of this invention, overlapping description is abbreviate|omitted here.

Although there is no restriction|limiting in particular in the manufacturing method of the PVA type polymer film (2), According to the manufacturing method of the PVA type polymer film of this invention mentioned later, since the target PVA type polymer film (2) can be manufactured simply, it is preferable. . In this case, the side which contact|connects the surface of a metal support body tends to become a surface which has a larger one-sided mean square roughness. In addition to the above production method, a method of passing a PVA-based polymer film formed into a film between metal rolls having different surface roughness, or a foreign material in a film-forming undiluted solution used for the production of a PVA-based polymer film (deteriorated resin or kontami from the outside) nation, etc.) using a filter or the like, and adding ultrafine particles of inorganic substances to the undiluted solution to form a film on a smooth surface to adjust the average square roughness of both surfaces, etc. are conceivable.

[Film Roll (2)]

The film roll (film roll (2)) of the present invention is made by continuously winding a long PVA-based polymer film as the above-described PVA-based polymer film (2), for example, a PVA-based polymer film ( As 2), a long PVA-based polymer film is continuously wound. When a cylindrical core is used, it is preferable that both ends of the core form protrusions protruding from the end face of the film roll. As the said core, the thing mentioned above as description of the film roll 1 can be used, and the overlapping description is abbreviate|omitted here.

Also about the other structure concerning the film roll 2 of this invention, since it can be set as the thing similar to the above as description of the film roll 1 of this invention, overlapping description is abbreviate|omitted here.

In the film roll 2 of this invention, generation|occurrence|production of the wrinkle which tends to generate|occur|produce when the conventional film roll is being stored can be reduced. The temperature at the time of storing the film roll is preferably 40°C or less, more preferably 35°C or less, and still more preferably 30°C or less, from the viewpoint that when too high, the PVA-based polymer film is deformed and wrinkles are easily generated. . On the other hand, although there is no restriction|limiting in particular in the lower limit of the temperature at the time of storing a film roll, It is preferable that the said temperature is -10 degreeC or more, It is more preferable that it is -5 degreeC or more, It is still more preferable that it is 0 degreeC or more.

[Method for producing PVA-based polymer film]

The production method of the present invention for producing a PVA-based polymer film has a chromium plating layer on the surface, the surface hardness is 550 HV or more and less than 900 HV in Vickers hardness, and the surface temperature is 50° C. or more and 115° C. or less on the surface of a metal support. , a process of forming a film by casting and drying a PVA-based polymer in a solution state or a molten state. And, immediately before starting to cast the PVA-based polymer in the solution or molten state, the area (product of the maximum width and the maximum distance between the ends) on the surface of the metal support is 200 µm ² or more The number of cracks is 0.7 pieces/mm 2 or less to be. According to this manufacturing method, in the above-described PVA-based polymer films (PVA-based polymer films (1) and (2)) of the present invention and film rolls (film rolls (1) and (2)) of the present invention, A long PVA-based polymer film to be wound can be easily produced.

A drum, a belt, etc. are mentioned as a metal support body used in this invention, It has a chromium plating layer on the surface. Here, the surface of the metal support means a surface (film-forming surface) on which the PVA-based polymer in a solution state or a molten state is cast, and when the metal support is a drum, it is enough to have a chrome plating layer on the outer peripheral surface of the drum, and in the case of a belt What is necessary is just to have a chrome plating layer on the surface outside among the continuous surfaces of a belt.

Although there is no restriction|limiting in particular in the thickness of a chromium plating layer, It is preferable that it exists in the range of 10 micrometers or more and 500 micrometers from the point which can prevent corrosion of the surface of a metal support body more effectively, and it is easy to reduce the number of cracks mentioned later. In addition, the chrome plating layer may be formed at once or may be formed by dividing it into a plurality of times. For example, when the chrome plating layer is formed by dividing the chrome plating layer into a plurality of times, once the chrome plating layer is formed, the surface irregularities are polished What is necessary is just to remove it by etc., and to form an additional chrome plating layer on it. In this way, pinholes in the chromium plating layer can be reduced. Moreover, as described in patent document 4 etc., when a nickel plating layer is formed under a chrome plating layer, the crack in a chrome plating layer can be reduced more.

The said metal support body which has a chrome plating layer on the surface WHEREIN: The surface hardness needs to be 550 HV or more and less than 900 HV in Vickers hardness. A general metal support having a chromium plating layer is known (for example, refer to Patent Documents 4 to 7, etc.). However, if a metal support having a specific surface hardness as in the present invention is used, the reason is unknown, but a film such as buff polishing or the like is used. The number of cracks present on the surface of the metal support can be easily reduced by the general treatment performed on the surface of the metal support before the start of production, and the number of the defects A in the obtained PVA-based polymer film is reduced than before. Moreover, even if a PVA-type polymer film is continuously formed into a film over a long period of time, the fluctuation|variation in the number of the said fault A can be maintained at a level lower than before. Moreover, the square average roughness of both surfaces of a film can be adjusted to a desired range. When the surface hardness is 900 HV or more in terms of Vickers hardness, it becomes difficult to reduce the number of cracks present on the surface of the metal support, and when a PVA-based polymer film is continuously formed over a long period of time, the defect A change in numbers increases. In addition, the average square roughness of both surfaces of the film tends to deviate from the desired range. From the above viewpoints, the surface hardness is Vickers hardness, preferably less than 800 HV, more preferably less than 780 HV. On the other hand, when the surface hardness is less than 550 HV in terms of Vickers hardness, it is easy to cause problems such as scratches during continuous film production or cleaning the surface of the metal support, and when the PVA-based polymer film is continuously formed over a long period of time The variation in the number of defects A also increases. In addition, the average square roughness of both surfaces of the film tends to deviate from the desired range. From such a viewpoint, it is preferable that the said surface hardness is 600 HV or more in Vickers hardness, It is more preferable that it is 650 HV or more, It is still more preferable that it is 700 HV or more.

The surface hardness of a metal support body can be calculated|required by measuring the Vickers hardness of the surface of a chrome plating layer at several points using a hardness meter etc., and averaging them. In addition, the measurement of the said surface hardness (Vickers hardness) may be performed on the surface (film formation surface) on which the PVA-type polymer in a solution state or a molten state is cast|flow_spread, but the flaw generated at the time of measurement reduces the quality of the PVA-type polymer film obtained Since there is a possibility of making the product, near the surface (film formation surface) on which the PVA polymer in a solution state or molten state is cast, such as a portion where a chrome plating layer is formed at the end of a drum or a belt, or in a solution state or molten state Even if it is the surface (film formation surface) on which the PVA-based polymer of PVA-based polymer is cast, the surface hardness is measured on the surface corresponding to the film portion to be removed by edge cut or the like after film formation, and the value is determined as the surface hardness specified in the present invention. do it with The surface hardness of a metal support body can be specifically calculated|required by the method mentioned later in an Example.

Adjustment of the surface hardness of the metal support having a chromium plating layer on its surface can be easily carried out by a known method, specifically, a method of adjusting the temperature of the chromium plating bath used in the chromium plating process to be within a specific range ; A method of adjusting the current density during the chrome plating process within a specific range; How to adjust the composition of the chrome plating bath; It can be carried out by a method of adjusting the concentration of hydrogen occluded in the chrome plating layer by heat treatment (annealing) or exposure to hydrogen gas after the chrome plating treatment. Among these, the method of adjusting the temperature of a chrome plating bath within a specific range from a point etc. which are easy to operate; A method of adjusting the current density during the chrome plating process within a specific range; The method of adjusting the hydrogen concentration occluded in the chrome plating layer after a chrome plating process is preferable, and the method of adjusting the temperature of a chrome plating bath within a specific range is more preferable. With respect to the above method, using a chromic acid-sulfuric acid aqueous solution, which is a general chromium plating bath, the temperature of the chromium plating bath is in the range of 40°C or more and 70°C or less, and the current density is in the range of 60 A/dm 2 or less. Taking the case of performing the chrome plating treatment as an example, the surface hardness tends to be generally lower as the temperature of the chrome plating bath is higher and the current density is lower. In addition, with respect to the concentration of hydrogen occluded in the chrome plating layer, the surface hardness tends to generally decrease as the temperature of the heat treatment is increased or the treatment time is increased to decrease the concentration.

The method for forming the chromium plating layer is not particularly limited as long as the surface hardness is a method capable of making a metal support within the above range, and a known method can be employed. As a representative method, first, the surface of the metal support is polished by a method such as buffing or grinder polishing to remove as much as possible irregularities on the surface, and then subjected to a base treatment such as immersion degreasing, electrolytic degreasing, immersion in hydrochloric acid aqueous solution, etc., and then chrome plating using a chrome plating bath A method of treating and further heat-treating is exemplified. As a chromium plating bath, a Sergeant bath is typical, and this can be used preferably. Examples of the composition of the Sergent bath and the conditions of the chromium plating treatment are shown below.

<Composition of Sargent Bath>

Chromic acid anhydride: 100 ~ 300 g/ℓ (concentration based on the chemical used)

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

<Conditions for chrome plating treatment>

Current density 10 to 60 A/dm2

The temperature of the chromium plating bath greatly affects the surface hardness of the metal support obtained as described above. The specific temperature of the chromium plating bath is preferably 50°C or higher, more preferably 53°C or higher, and 54°C or higher, although it may vary depending on other conditions employed in the chrome plating treatment and the conditions of heat treatment after the chrome plating treatment. More preferably. When the temperature of the chromium plating bath is too low, the surface hardness of the metal support body obtained becomes high easily too much. On the other hand, it is preferable that the temperature of a chrome plating bath is 66 degrees C or less, It is more preferable that it is 63 degrees C or less, It is more preferable that it is 61 degrees C or less, It is especially preferable that it is 58 degrees C or less. When the temperature of a chrome plating bath is too high, the surface hardness of the metal support body obtained becomes low easily too much.

It is preferable to perform heat processing (annealing) after a chrome plating process. When heat treatment is performed at high temperature, the time required for it can be shortened, but if the temperature is too high, cracks are likely to occur in the chromium plating layer. Therefore, the temperature of the heat treatment is preferably 130°C or less, and 120°C or less is more desirable. Conversely, when the heat treatment is performed at a low temperature, the risk of cracking is lowered, but the time required for the heat treatment becomes longer. Therefore, the heat treatment temperature is preferably 70°C or higher, and more preferably 90°C or higher. The heat treatment time may vary depending on the conditions of the chrome plating treatment, the temperature of the heat treatment, and the like, but can be set within the range of 24 to 120 hours.

Examples of the PVA-based polymer in a solution state or a molten state include a film-forming stock solution in which a PVA-based polymer is dissolved in a liquid medium, a PVA-based stock solution containing a PVA-based polymer and a liquid medium and a PVA-based polymer melted, and the like. and those in the form of a film-forming stock solution containing a polymer and a liquid medium. The film-forming stock solution may further contain the same plasticizer, surfactant, and other components as described above, if necessary.

As the liquid medium in the film-forming stock solution, for example, water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, tri Ethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine, diethylenetriamine, etc. are mentioned, Among these, 1 type, or 2 or more types can be used. Among them, water is preferable in terms of a small load on the environment and a point of recoverability. That is, as a preferable example of a PVA-type polymer in a solution state or a molten state, the thing in the form of the film-forming stock solution containing a PVA-type polymer and water is mentioned.

The volatile fraction of the film-forming undiluted solution (the content ratio in the film-forming undiluted solution of volatile components such as a liquid medium removed by volatilization or evaporation at the time of film formation) varies depending on the film-forming method, the film-forming conditions, etc., but is 50 to It is preferable to exist in the range of 90 mass %, and it is more preferable to exist in the range which is 55-80 mass %. When the volatilization fraction of the film-forming undiluted solution is 50 mass % or more, the viscosity of the film-forming undiluted solution does not become too high, and filtration and defoaming at the time of preparing the film-forming undiluted solution are smoothly performed. becomes easier On the other hand, when the volatilization fraction of the film forming undiluted solution is 90 mass % or less, the concentration of the film forming undiluted solution does not become too low, and manufacture of an industrial PVA-type polymer film becomes easy.

There is no particular limitation on the method for preparing the above film-forming stock solution, for example, a PVA-based polymer is dissolved in a liquid medium such as water, and at that time, at least one of a plasticizer, a surfactant, and other components is added as needed. method or a method of melt-kneading a PVA-based polymer containing a liquid medium such as water using an extruder, and melt-kneading at least one of a plasticizer, a surfactant, and other components as necessary at that time. can be heard

In the production method of the present invention for producing a PVA-based polymer film, the PVA-based polymer in a solution state or a molten state is cast and dried on the surface of the metal support having a surface temperature of 50° C. or more and 115° C. or less to form a film. It has a manufacturing process. When the surface temperature of a metal support body exceeds 115 degreeC, the number of faults A will increase in the PVA-type polymer film obtained. In addition, the average square roughness of both surfaces of the film tends to deviate from the desired 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, still more preferably 99°C or lower, particularly preferably 96°C or lower, and most preferably 95°C or lower. On the other hand, when the surface temperature of a metal support body is less than 50 degreeC, it becomes easy to generate|occur|produce the problem, such as peeling of the film from a metal support body becoming difficult, or transparency of a film being impaired. From such a viewpoint, it is preferable that the surface temperature of a metal support body is 60 degreeC or more, It is more preferable that it is 70 degreeC or more, It is still more preferable that it is 80 degreeC or more. In addition, as surface temperature of a metal support body, what is necessary is just to employ|adopt the average value (average temperature) of the surface temperature of several arbitrary points (for example, 10 points or more) on the surface of a metal support body.

There is no particular limitation on the method of bringing the surface temperature of the metal support within the above range before the start of film production. For example, in the case of using a drum as a metal support, a medium such as water, oil, or water vapor is passed through the inside of the drum. Alternatively, heating by a dielectric heating heater installed inside the drum, or heating by an infrared heater or a hot air heating device installed to face the surface of the drum may be employed.

Regarding the alternate temperature rate when the surface temperature of the metal support is within the above range before the start of film production, for example, as described in Patent Document 5, it can be 3° C./hour or less, but it has a chrome plating layer on the surface , In the manufacturing method of the present invention using a metal support having the above-described surface hardness, the reason is unknown, but the increase in the number of cracks present on the surface of the metal support can be suppressed even if the alternate temperature rate is relatively high, Even when the temperature adjustment time was reduced and productivity was improved, it discovered that the number of the said fault A in the PVA type polymer film obtained was controllable to a low level. From such a viewpoint, the temperature change rate at the time of bringing the surface temperature of the metal support within the above range before the start of film production is preferably 0.5 °C/hour or more, more preferably 1 °C/hour or more, and 3.5 °C/hour or more, It is good also as 4 degrees C/hour or more, 4.5 degrees C/hour or more, and also 5 degrees C/hour or more. Moreover, it is preferable that it is 10 degrees C/hour or less from a viewpoint of reducing the number of cracks, and, as for the said change temperature rate, it is more preferable that it is 7 degrees C/hour or less.

In addition, when making the surface temperature of a metal support body within the said range before film production start, it is preferable from a viewpoint of reducing a crack to make small the temperature difference of the width direction of a metal support body, Specifically, the surface temperature of a metal support body is width direction With respect to the temperature distribution data obtained by continuously measuring with , when a graph is made with the position in the width direction as the horizontal axis and the temperature as the vertical axis, it is preferable that the maximum value of the absolute value of the inclination is 10 ° C / m or less, and 5 ° C / m It is more preferable that it is m or less, It is still more preferable that it is 4 degrees C/m or less, It is especially preferable that it is 3 degrees C/m or less.

Further, in the production method of the present invention for producing a PVA-based polymer film, immediately before starting to cast the PVA-based polymer in a solution state or a molten state, the area on the surface of the metal support is 200 µm ² or more of cracks The number is 0.7 pieces/mm 2 or less. Here, the crack area means the product of the maximum width of the crack and the distance between the maximum ends. In general, cracks such as cracks in the chromium plating layer exist on the surface of the metal support before the start of film production. And it is thought that foreign substances considered as resin deposits gradually adhere to such cracks during film formation to form a convex shape, which is transferred to the film to form a defect A on the film. In particular, since the PVA-based polymer has high hydrophilicity and good affinity with metals compared to other polymers, it is thought that it is easy to enter cracks existing on the surface of the metal support and adhere as a resin deposit, and the dried film is peeled from the metal support. It is thought that it is easy to form and grow a convex shape at the time of doing this etc. 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. As described above, a metal having a chrome plating layer on the surface and having the above surface hardness When a support is used, although the reason is unknown, the number of cracks existing on the surface of the metal support can be easily reduced by a general treatment applied to the surface of the metal support before the start of film production, such as buffing, etc., and the resulting PVA The number of the defects A in the polymer film can be reduced compared to the prior art, and even if the PVA polymer film is continuously formed over a long period of time, the fluctuation in the number of the defects A can be maintained at a lower level than before. . When the number of the said cracks in the surface of a metal support body exceeds 0.7 piece/mm<2>, in the PVA-type polymer film obtained, the number of faults A will increase. From the viewpoint of reducing the number of defects A in the obtained PVA-based polymer film, etc., immediately before starting to cast the PVA-based polymer in a solution state or a molten state, the number of cracks on the surface of the metal support is 0.3 pieces It is preferable that it is /mm<2> or less, and it is more preferable that it is 0.15 piece/mm<2> or less. On the other hand, since it is complicated to extremely reduce the number of cracks on the surface of the metal support and the effect tends to reach a limit, the number is preferably 0.005 cracks/mm 2 or more, and more preferably 0.01 cracks/mm 2 or more. Do.

The number of cracks having an area of 200 μm ² or more on the surface of the metal support is in the range of 2 mm × 2 mm (4 mm 2 ) using a microscope, in which 25 arbitrary points are determined on the surface of the metal support. "Size of cracks 200 ㎛ ² or more" specifies a in, and by obtaining the number of "area 200 ㎛ ² or more cracks" in the range of × 25 points of that 4 ㎟, calculate the number per 1 ㎟ from this can be saved Here, the crack area means the product of the maximum width and the maximum distance between the ends of each crack, and the maximum distance between the ends means the distance between the ends (straight line distance) when there are only two ends of the crack. case, it means the maximum distance among the distances between the plurality of ends. ^{The number of cracks having an area of 200 µm 2} or more on the surface of the metal support can be specifically calculated by the method described later in Examples.

The width of the metal support can be appropriately set according to the width of the target PVA-based polymer film. Although the specific width of the metal support depends on the width of the desired PVA-based polymer film, it is, for example, 0.5 m or more, and a wide PVA-based polymer film capable of producing a wide-width polarizing film efficiently From a manufacturing viewpoint, it is preferable that it is 4.5 m or more, It is more preferable that it is 5.0 m or more, It is still more preferable that it is 5.5 m or more. Moreover, when the cost of a metal support body, easiness of maintenance, etc. are considered, it is preferable that the width of the said metal support body is 7.5 m or less, It is preferable that it is 7.0 m or less, It is more preferable that it is 6.5 m or less.

There is no particular limitation on the method of casting the PVA-based polymer in solution or molten state on the surface of the metal support, and using a T-type slit die, hopper plate, I-die, lip coater die, etc., according to a known method can be carried out. Moreover, it is preferable that the temperature of the PVA-type polymer in a molten state or a solution state exists in the range of 50 degreeC or more and 105 degrees C or less.

Drying after casting can be performed by a well-known method, and can be performed by drying with the heat|fever given from a metal support body, or hitting a hot air. In addition, the desired PVA-based polymer film may be produced only by drying on the surface of the metal support, but after partial drying on the surface of the metal support by a known method or the like, disposed on the downstream side of the metal support, the A desired PVA-based polymer film may be produced by further drying with one or two or more drying rolls having a metal support and a rotational axis parallel to each other, or a hot air dryer.

Thus, the obtained PVA-type polymer film can be heat-processed as needed, or the width direction both ends (edge part) can be cut. Moreover, it is good also as a film roll by winding up continuously as mentioned above.

[Usage]

The PVA-based polymer films of the present invention (PVA-based polymer films (1) and (2)) or the PVA-based polymer films unwound from the film rolls of the present invention (film rolls (1) and (2)) have the number of defects A write; The quality is stable; Although it can be used for various uses by taking advantage of the advantage of less wrinkling, it is preferable to use it as a raw film for optical film production, such as a polarizing film or retardation film, from the viewpoint of showing the effect of the present invention more conspicuously, It is more preferable to use it as a raw film for polarizing film manufacture.

There is no particular limitation on a method for producing a polarizing film using the above PVA-based polymer film as a raw film, and a known method can be employed. For example, using the above-described PVA-based polymer film, dyeing, uniaxial What is necessary is just to perform extending|stretching, a fixing process, drying, and also washing|cleaning and heat processing as needed. Here, the order in particular of each process, such as dyeing|staining, uniaxial stretching, and a fixing process, is not restrict|limited, One or two or more processes may be implemented simultaneously. In addition, one or two or more of each process may be performed twice or more, for example, uniaxial stretching may be performed two times or more times. Before performing each process, such as dyeing|staining, uniaxial stretching, and a fixation process, you may perform a swelling process as needed.

You may perform dyeing at any stage before uniaxial stretching, at the time of uniaxial stretching, and after uniaxial stretching. As dye used for dyeing, 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 Violet 9, 12, 51, 98; Direct Green 1, 85 ; Direct Yellow 8, 12, 44, 86, 87; One type or two or more types among dichroic dyes, such as direct orange 26, 39, 106, 107, etc. can be used. Dyeing can be performed by immersing a PVA-type polymer film in the solution (dyeing bath) containing the said dye. Moreover, when forming a film of a PVA-type polymer film, you may make it contain said dye previously.

Uniaxial stretching may be performed by either wet stretching method or dry heat stretching method, may be performed in warm water (including the above-described dyeing bath or a fixed treatment bath described later), or using a PVA-based polymer film after absorption It can also be carried out in air.

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

It is preferable that it is 4 times or more from the point of polarization performance, and, as for the draw ratio of uniaxial stretching (in the case of uniaxial stretching in multiple stages, it is more preferable, it is more preferable that it is 5 times or more). Although there is no restriction|limiting in particular in the upper limit of a draw ratio, Since it is easy to perform uniaxial stretching stably if it is 8 times or less, it is preferable. Although the thickness of the film after uniaxial stretching varies depending on the thickness of the PVA-based polymer film to be used, it 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.

A fixing treatment is often performed for the purpose of strengthening the adsorption of the dye to the PVA-based polymer film. As a fixed treatment bath used for a fixed treatment, the aqueous solution containing 1 type, or 2 or more types of boron compounds, such as boric acid and borax, can be used. You may add an iodine compound to a fixed treatment bath as needed.

After performing each treatment such as dyeing, uniaxial stretching, and fixing treatment, washing is preferably performed before drying in order to remove the treatment bath liquid and foreign matter of each treatment adhering to the film surface. Pure water may be used for the washing|cleaning liquid used for washing|cleaning, and in order to suppress the outflow of dye and a boron compound by washing|cleaning, you may use water to which these chemical|medical agents were added in small amounts. A washing liquid may be implemented by spraying on the surface of the film which passed through each process by shower etc., and you may implement by immersing the film which passed each process in a washing bath.

It is preferable to perform drying and heat processing within the range of 30 degreeC or more and 150 degrees C or less, and it is more preferable to perform within the range of 50 degreeC or more and 150 degrees C or less.

Using the PVA-based polymer film (2) or the PVA-based polymer film unwound from the film roll (2) as a raw film for polarizing film production, each step of the dyeing step, the uniaxial stretching step, the fixed treatment step, and the drying step In the case of manufacturing a polarizing film through the drying process, when exiting the last treatment bath (eg, a fixed treatment bath or a washing bath) before entering the drying process, the angle between the liquid level of the treatment bath and the film surface (angle on the acute angle side) ) to 30° or more and 85° or less, and the surface on the upper side of the film is the surface having the smaller square average roughness in the PVA-based polymer film used as the raw film, a polarizing film with less foreign matter It is preferable because it can be obtained easily.

Although the reason the said effect appears is not necessarily clear, it is thought that it is because adhesion of the PVA-type polymer which precipitated in each process bath, and the process liquid used by each process by manufacturing a polarizing film as mentioned above is reduced. The angle between the liquid level of the treatment bath and the film surface when exiting the last treatment bath before entering the drying step is too large or too small, from the viewpoint that the precipitated PVA polymer or treatment liquid tends to adhere and remain, the angle is 35 It is preferable that it is ° or more, It is more preferable that it is 40 degrees or more, It is more preferable that it is 50 degrees or more, It is preferable that it is 80 degrees or less, It is more preferable that it is 75 degrees or less, It is more preferable that it is 70 degrees or less.

The polarizing film obtained by making it above is normally used by bonding together the protective film which is optically transparent and has mechanical strength on the both surfaces or single side|surface, and is used as a polarizing plate. As the protective film, a cellulose triacetate (TAC) film, a cellulose acetate/butyrate (CAB) film, an acrylic film, a polyester film, or the like is used. Moreover, although a PVA type adhesive agent, a urethane type adhesive agent, etc. are mentioned as an adhesive agent for bonding, Especially, a PVA type adhesive agent is preferable.

Example

Hereinafter, although an Example etc. demonstrate this invention concretely, this invention is not limited at all by these. In addition, each measurement or evaluation method employ|adopted in the following preparation examples, an Example, a reference example, and a comparative example is shown below.

[Measurement of surface hardness of drum for film production]

On the surface (peripheral surface) of the drum for film formation, on a line each 5 mm inward from both ends, a total of 8 points was determined so that the total perimeter of the drum for film formation might be divided into 4 equal parts by 4 points at each end. And at each point, the Vickers hardness of the surface of the chrome plating layer is measured with a UCI type hardness meter MIC10 (manufactured by GE Sensing & Inspection Technologies, Inc.; MIC-2101-A is used for the probe), and the average value thereof is measured on the surface of the film-forming drum. It was made into hardness.

[Measurement of the number of cracks ^{having an area of 200 µm 2} or more on the surface of the film-forming drum]

Arbitrary 25 points were determined on the surface (peripheral surface) of the film-forming drum, and in each, 2 mm × 2 mm (4 mm 2 ) using a digital video microscope VHX-900 (manufactured by Keyence Corporation) at a magnification of 1000 times. ) of cracks (cracks on the chromium plating layer) in the range of ) were taken. And the maximum width and the maximum distance between the ends of each crack shown in the photo (when there are only two ends, it means the distance between those ends, and when there are plural ends, it means the maximum distance among the distances between the plurality of ends) in μm unit calculated by obtaining the product thereof, and the multiplication of a crack that is more than 200 ㎛ ² was referred to as "area 200 ㎛ ² or more cracks." ^{In this way, the number of "cracks with an area of 200 m 2} or more" was calculated|required in the said range of 4 mm<2> x 25 points, and the number per 1 mm<2> was calculated from this.

[Measurement of surface temperature of drum for film production]

One straight line in the width direction passing through any one point on the surface (peripheral surface) of the film-forming drum, and the other three straight lines parallel to this one straight line and dividing the peripheral surface into quarters together with this one straight line (i.e., the film-forming drum A straight line positioned on the same straight line for every 1/4 round) was determined, and the temperature distribution on these 4 straight lines was measured using a thermotracer TH9100MR (manufactured by NEC Avio Infrared Technology Co., Ltd.). Next, from the obtained temperature distribution data, the temperature of each of three points (12 points in total) at a position of 20 cm from the center in the width direction and from both ends to the center is obtained from the obtained temperature distribution data, and the average of the temperatures of these 12 points is calculated as It was set as the surface temperature of the drum for film forming at the time. In addition, the obtained temperature distribution data for each straight line is made into four graphs with the position in the width direction as the horizontal axis and the temperature as the vertical axis, the maximum value of the absolute value of the slope is obtained, and this is the maximum temperature gradient of the drum for film production at that time. was done with

[Measurement of the number of defects in the PVA film]

While unwinding the PVA film from the film roll, the film passed through the film, and defects of the film were found from the distortion of the image of the fluorescent lamp when viewing the fluorescent lamp placed behind it, and the periphery was wrapped around it with an oil-based marker. Next, the detected defect was observed using a non-contact surface shape measuring instrument "NewView" 6300 (manufactured by Zygo), and as a defect dented from the film surface, an area (opening area) of 400 µm ² or more and a depth of 0.3 µm or more ( Defect A) was determined whether or not it was recognized. The above operation was carried out from the winding end portion in the produced film roll (in addition, the portion 10 m from the end in the longitudinal direction of the film was excluded in order to reduce errors), until the number of defects A became ten. The area of the PVA film (length from the start of operation to the tenth defect A × film width; unit is m2) of the PVA film of The number (units/m 2 ) was calculated. Also, among the ten defects A, two or more defects which are substantially at the same position in the width direction of the film and are in a relationship substantially coincident with an interval in the longitudinal direction of the film by an integer multiple of the total circumference length of the used film forming drum ( Hereinafter, it is sometimes referred to as a “rotational cycle defect.” In addition, such a defect is substantially constant in the longitudinal direction of the film, including portions other than the portion provided for measurement (integer multiple of the total circumference of the film-forming drum) It can be considered that three or more are arranged at an interval.), and dividing this by the area (unit: m2), the number of defects in the rotation cycle at the end of winding (units/m2) was calculated.

Subsequently, as described later using the remaining film rolls, a polarizing film (polarizing film prepared from a PVA film on the winding end side) is prepared, and then the PVA film is removed from the remaining film roll in which most of the PVA films are in an unused state. By unwinding and rewinding to a film roll anew, it was made for the winding-up start part of the original film roll to be located in the outer side of a new film roll. Perform the same operation as above using this new film roll, find the number of defects A and rotation cycle defects (all units/m2) in the winding start part of the original film roll, and use the remaining film rolls A polarizing film (the polarizing film manufactured from the PVA film by the side of a winding start part) was manufactured so that it might mention later.

[Evaluation of wrinkle of film roll]

The film roll was visually observed, and the following references|standards evaluated wrinkles.

Rank A: No wrinkles

Rank B: There are some wrinkles, but there is no problem in practical use

Rank C: Practically problematic level of wrinkles

[Measurement of mean square roughness of PVA film]

The average square roughness of ten arbitrary points on one surface of the PVA film was measured using a white interference microscope NV6300 (manufactured by Zygo Corporation), and their average value was set as the average square roughness of the surface. Then, it carried out similarly also about the other surface of a PVA film, and obtained square average roughness.

[Evaluation of polarizing film (20 sheets test)]

The PVA film unwound from the said film roll was processed continuously in order of preliminary|backup swelling, dyeing|staining, uniaxial stretching, a fixed process, drying, and heat processing, and the polarizing film was produced.

That is, the PVA film was pre-swelled by immersion in water at 30°C for 30 seconds, followed by immersion in an aqueous solution (dye bath) at 35°C having an iodine concentration of 0.4 g/L and a potassium iodide concentration of 40 g/L for 3 minutes for dyeing. Then, in the 50 degreeC aqueous solution (stretching bath) of 4% of boric acid concentration, it uniaxially stretches at a draw ratio 5 times in the longitudinal direction, and also potassium iodide density|concentration 40 g/L, boric acid density|concentration 40 g/L, and zinc chloride. The fixed treatment was performed by immersing in a 30°C aqueous solution (fixed treatment bath) having a concentration of 10 g/L for 5 minutes. Then, the film was hot-air-dried at 40 degreeC, and also heat-processed at 100 degreeC for 5 minute(s).

From the arbitrary positions of the obtained polarizing film, 20 pieces of 25 cm test pieces were extract|collected to 50 cm and the width direction in a longitudinal direction. On the other hand, a 50 cm x 50 cm polarizing plate with few defects is prepared, and each of the above test pieces is superimposed on this polarizing plate so that the orientation axis is perpendicular, and it is placed on a Schaukasten for Rentgen photographic observation, and each test piece defects were confirmed. In addition, when there is no defect in the test piece, the overlapped polarizing plate/test piece looks black, but when the test piece has a defect, light leaks from that part and it can be recognized as a dotted bright defect. The test piece in which two or more of these bright defects were observed was set as rejection, and the pass rate in the test piece of 20 sheets was computed.

[Evaluation of polarizing film (100 sheets test)]

The number of test pieces was changed from 20 to 100, and the pass rate in the 100 test pieces was calculated in the same manner as in the 20-sheet test, except that the test piece in which one or more bright defects were observed was rejected.

[Evaluation of staining stains and foreign matter of polarizing film]

From the arbitrary positions of the obtained polarizing film, the 25 cm test piece was extract|collected in 50 cm and the width direction in a longitudinal direction. On the other hand, prepare a 50 cm x 50 cm polarizing plate with few staining irregularities and foreign substances, and superimpose the test piece on this polarizing plate so that the orientation axis is perpendicular, and place it on the Shaukasten for Rentgen photographic observation, and the test piece The staining unevenness and foreign matter in the were evaluated according to the following criteria.

・Dyeing stains

Rank A: No staining stains

Rank B: There is some staining of dyeing, but there is no problem in practical use

Rank C: There is a level of dye staining that is problematic in practice

· Foreign matter

Rank A: No foreign matter confirmed

Rank B: A level with a small amount of foreign matter, but no problem in practical use

Rank C: There is a level of foreign matter that is problematic in practice

[Preparation Example 1]

《Preparation of Drum 1》

After buffing the drum surface (peripheral surface) of a 1.0 m-wide carbon steel film-making drum for base treatment such as degreasing, chrome plating treatment is performed on the drum surface using a chrome plating bath under the following conditions. did. In addition, what dissolved these chemicals in distilled water so that it might become 200 g/L of chromic anhydride and 2 g/L of sulfuric acid at the concentrations based on the chemical|medical agent used was used as a chrome plating bath.

· Chrome plating bath temperature: 55 ℃

· Current density: 20 A/d㎡

· Chrome plating layer thickness (after polishing): 50 ㎛

And after completion|finish of a chrome plating process, the said film-forming drum was heat-processed at 102 degreeC for 50 hours, and it stood to cool.

As a result of measuring the surface hardness of the drum for film production in which a chrome plating layer was formed on the surface (peripheral surface) by the above chrome plating treatment and heat treatment according to the above method, it was 760 HV. Hereinafter, this drum for film forming is called "drum 1".

[Preparation Example 2]

《Preparation of Drum 2》

Chrome plating treatment and heat treatment were performed in the same manner as in Preparation Example 1 except that the chrome plating bath temperature was changed to 52°C, to prepare a film forming drum in which a chrome plating layer was formed on the surface (peripheral surface). As a result of measuring the surface hardness of this film-forming drum according to the above method, it was found to be 840 HV. Hereinafter, this drum for film forming is called "drum 2".

[Preparation Example 3]

《Preparation of Drum 3》

Chrome plating treatment and heat treatment were performed in the same manner as in Preparation Example 1 except that the chrome plating bath temperature was changed to 48°C, to prepare a film forming drum in which a chrome plating layer was formed on the surface (peripheral surface). As a result of measuring the surface hardness of this film-forming drum according to the method described above, it was found to be 950 HV. Hereinafter, this drum for film forming is called "drum 3".

[Preparation Example 4]

《Preparation of Drum 4》

Chrome plating treatment and heat treatment were performed in the same manner as in Preparation Example 1 except that the chrome plating bath temperature was changed to 67°C, to prepare a film forming drum in which a chrome plating layer was formed on the surface (peripheral surface). As a result of measuring the surface hardness of this film-forming drum according to the above method, it was 525 HV. Hereinafter, this drum for film forming is called "drum 4".

[Example 1]

Drum 1 was mounted on a cast film production facility and connected to a hot water circulation device. Then, the peripheral surface of drum 1 was buff-polished. ^{The number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after buffing was measured by the above method, and as a result, it was 0.10 pieces/mm 2 . Then, the surface temperature of the drum 1 was raised at the alternate temperature rate of 1 degreeC/hour by the hot water circulation device, and it maintained at the surface temperature of 90 degreeC. The maximum temperature gradient at this time was 3.8°C/m at the maximum.

On the other hand, 100 parts by mass of a chip of PVA (saponified product of a homopolymer of vinyl acetate) having a degree of saponification of 99.9 mol% and a degree of polymerization of 2,400 was immersed in 2,500 parts by mass of distilled water at 35°C for 24 hours, followed by centrifugal dehydration, and PVA water-containing chips got The volatile fraction in the PVA water-containing chip was 70 mass%. To 333 parts by mass of the PVA water-containing chip (100 parts by mass in terms of dry PVA), 12 parts by mass of glycerin and 0.3 parts by mass of a surfactant (containing 95 mass% of diethanolamide lauric acid) were added, and then mixed well to obtain a mixture. And this was heat-melted by the twin screw extruder with a vent with a maximum temperature of 130 degreeC. After cooling the obtained molten PVA to 100°C with a heat exchanger, it is extruded from a coat hanger die having a width of 900 mm on the drum 1 having a surface temperature of 90°C, and further passed through a hot air drying furnace and dried It was made and the width direction both ends (edge part) was cut, and the long PVA film of width 0.7m was manufactured continuously. In addition, the film-forming speed|rate was 8 m/min. The PVA film (thickness 60 micrometers, length 8,000 m) after film|membrane formation was stabilized was continuously wound up on the 6-inch-diameter aluminum cylindrical core, and it was set as the film roll.

Using the obtained film roll, as a result of performing the measurement of the number of defects of the PVA film and evaluation of the polarizing film (20 sheet test) by the method described above, the number of defects A in the winding start part was 0.102 pieces/m 2 ( Among them, the pass rate in the 20-sheet test of the polarizing film manufactured from the PVA film on the side of 0.031 piece/m2) and the winding start part is 100%, and the number of fault A in the winding end part is 0.098 pieces. The pass rate in the 20-sheet test of the polarizing film manufactured from /m<2> (in that, a rotation cycle fault is 0.029 piece/m<2>) and the PVA film by the side of the winding end part was 100 %. The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 0.96 times.

[Example 2]

Except having changed the length of the PVA film from 8,000 m to 3,000 m, it carried out similarly to Example 1, the PVA film was manufactured continuously, and it was set as the film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after the buffing was measured by the above method, and as a result, it was 0.11 pieces/mm 2 .

As a result of performing the measurement of the number of defects of the PVA film and evaluation (20 sheet test) of the polarizing film by the above method using the obtained film roll, the number of defects A in the winding start part was 0.110 pieces/m 2 ( Among them, the pass rate in the 20-sheet test of the polarizing film manufactured from the PVA film on the side of 0.044 piece/m2) and the winding start part is 100%, and the number of fault A in the winding end part is 0.121 piece of rotation cycle fault. The pass rate in the 20-sheet test of the polarizing film manufactured from /m<2> (a rotation cycle fault is 0.036 piece/m<2>) and the PVA film by the side of the winding end part was 100 %. The number of flaws A in the winding end part with respect to the number of flaws A in the winding-up start part was calculated by 1.10 times.

[Reference Example 1]

Except having changed the length of the PVA film from 8,000 m to 15,000 m, it carried out similarly to Example 1, the PVA film was manufactured continuously, and it was set as the film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after the buffing was measured by the above method, and as a result, it was 0.10 pieces/mm 2 .

As a result of measuring the number of defects of the PVA film by the above-described method using the obtained film roll, the number of defects A in the winding start part was 0.108 pieces/m 2 (of which, the rotation cycle defects were 0.032 pieces/m2) m 2 ) and the number of defects A in the winding end portion was 0.160 pieces/m 2 (of which, the number of defects in the rotation cycle was 0.096 pieces/m 2 ). The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 1.48 times.

[Example 3]

In the same manner as in Example 1 except that the polymerization degree 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, a PVA film was continuously manufactured to be a film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after the buffing was measured by the above method, and as a result, it was 0.10 pieces/mm 2 .

Using the obtained film roll, as a result of performing the measurement of the number of defects of the PVA film and evaluation of the polarizing film (100 sheets test) by the above method, the number of defects A in the winding start part was 0.088 pieces/m 2 ( Among them, the pass rate in the 100-sheet test of the polarizing film manufactured from 0.018 piece/m<2>) and the PVA film by the side of a winding start part is 98%, and the number of fault A in the winding end part is 0.118 The pass rate in the 100-sheet test of the polarizing film manufactured from /m<2> (the rotation cycle fault is 0.024 piece/m<2>) and the PVA film by the side of a winding end part was 95 %. The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 1.34 times.

[Example 4]

In the same manner as in Example 1 except that the polymerization degree 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, a PVA film was continuously manufactured to be a film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after the buffing was measured by the above method, and as a result, it was 0.13 pieces/mm 2 .

Using the obtained film roll, as a result of performing the measurement of the number of defects of the PVA film and evaluation of the polarizing film (100 sheets test) by the method described above, the number of defects A in the winding start part was 0.067 pieces/m 2 ( Among them, the pass rate in the 100-sheet test of the polarizing film manufactured from the PVA film on the side of 0.007 piece/m<2>) and the winding-up start part is 99 %, and the number of fault A in the winding-up completion part is 0.074 pieces. The pass rate in the 100-sheet test of the polarizing film manufactured from /m<2> (in that, rotation cycle fault is 0.007 piece/m<2>) and the PVA film at the side of the winding end part was 99 %. The number of flaws A in the winding end part with respect to the number of flaws A in the winding-up start part was calculated by 1.10 times.

[Example 5]

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, a PVA film was continuously manufactured to be a film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 2 after the buffing was measured by the above method, and as a result, it was 0.39 pieces/mm 2 .

Using the obtained film roll, as a result of performing the measurement of the number of defects of the PVA film and evaluation of the polarizing film (20 sheets test) by the above method, the number of defects A in the winding start part was 0.172 pieces/m 2 ( Among them, the pass rate in the 20-sheet test of the polarizing film manufactured from the PVA film on the side of 0.052 piece/m<2>) and the winding start part is 90 %, and the number of fault A in the winding end part is 0.224 piece of rotation cycle fault. The pass rate in the 20-sheet test of the polarizing film manufactured from /m<2> (a rotation cycle fault is 0.134 piece/m<2>) and the PVA film by the side of the winding end part was 85 %. The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 1.30 times.

[Example 6]

In the same manner as in Example 1 except that the surface temperature of 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, a PVA film was continuously manufactured to be a film roll . ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after the buffing was measured by the above method, and as a result, it was 0.13 pieces/mm 2 .

As a result of performing the measurement of the number of faults of the PVA film and evaluation (20 sheet test) of the polarizing film by the above method using the obtained film roll, the number of faults A in the winding start part was 0.132 pieces/m 2 ( Among them, the pass rate in the 20-sheet test of the polarizing film manufactured from the PVA film on the side of 0.053 piece/m<2>) and the winding start part is 95%, and the number of fault A in the winding end part is 0.180 piece of rotation cycle fault. The pass rate in the 20-sheet test of the polarizing film manufactured from /m<2> (a rotation cycle fault is 0.090 piece/m<2>) and the PVA film by the side of the winding end part was 90 %. The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 1.36 times.

[Example 7]

Except having changed the temperature change rate from 1 degree-C/hour to 5 degree-C/hour, it carried out similarly to Example 1, the PVA film was manufactured continuously, and it was set as the film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after the buffing was measured by the above method, and as a result, it was 0.10 pieces/mm 2 .

As a result of measuring the number of defects of the PVA film by the above method using the obtained film roll, the number of defects A in the winding start part was 0.110 pieces/m 2 (in which, the rotation cycle defects were 0.044 pieces/m2) m 2 ) and the number of defects A in the winding end portion was 0.122 pieces/m 2 (in which, the number of defects in the rotation cycle was 0.049 pieces/m 2 ). The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 1.11 times.

[Comparative Example 1]

Except having used the drum 3 instead of the drum 1, it carried out similarly to Example 1, the PVA film was manufactured continuously, and it was set as the film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 3 after the buffing was measured by the above method, and as a result, it was 0.73 pieces/mm 2 .

As a result of performing the measurement of the number of defects of the PVA film and evaluation of the polarizing film (20 sheet test) by the above method using the obtained film roll, the number of defects A in the winding start part was 0.291 pieces/m 2 ( Among them, the pass rate in the 20-sheet test of the polarizing film manufactured from 0.175 piece/m<2>) and the PVA film by the side of a winding start part is 80%, and the number of fault A in the winding end part is 0.938 The pass rate in the 20-sheet test of the polarizing film manufactured from /m<2> (in that, a rotation cycle fault is 0.750 piece/m<2>) and the PVA film by the side of the winding end part was 50 %. The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 3.22 times.

[Comparative Example 2]

In the same manner as in Example 1 except that the surface temperature of 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, a PVA film was continuously manufactured to be a film roll . ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after the buffing was measured by the above method, and as a result, it was 0.11 pieces/mm 2 .

Using the obtained film roll, as a result of performing the measurement of the number of defects of the PVA film and evaluation of the polarizing film (20 sheet test) by the method described above, the number of defects A in the winding start part was 0.252 pieces/m 2 ( Among them, the pass rate in the 20-sheet test of the polarizing film manufactured from 0.101 piece/m<2>) and the PVA film by the side of a winding start part is 80%, and the number of fault A in the winding end part is 0.358 piece. The pass rate in the 20-sheet test of the polarizing film manufactured from /m<2> (in that, a rotation cycle fault is 0.251 piece/m<2>) and the PVA film by the side of the winding end part was 65 %. The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 1.42 times.

[Comparative Example 3]

In Example 1, an attempt was made to produce a PVA film by changing the surface temperature of drum 1 from 90°C to 40°C, but drying on the drum was insufficient and it was difficult to peel the film from the drum, so each evaluation was performed Did not do it.

[Comparative Example 4]

Except having changed the temperature change rate from 1 degreeC/hour to 5 degreeC/hour, it carried out similarly to the comparative example 1, the PVA film was manufactured continuously, and it was set as the film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 3 after the buffing was measured by the above method, and as a result, it was 0.73 pieces/mm 2 .

As a result of measuring the number of defects of the PVA film by the above-described method using the obtained film roll, the number of defects A in the winding start part was 0.332 pieces/m 2 (of which, the rotation cycle defects were 0.166 pieces/m2) m 2 ) and the number of defects A in the winding end portion was 1.349 pieces/m 2 (of which, the number of defects in the rotation cycle was 1.214 pieces/m 2 ). The number of defects A in the winding end portion with respect to the number of defects A in the winding start portion was calculated to be 4.06 times.

[Example 8]

Drum 1 was mounted on a cast film production facility and connected to a hot water circulation device. Then, the peripheral surface of drum 1 was buff-polished. ^{The number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 1 after buffing was measured by the above method, and as a result, it was 0.10 pieces/mm 2 . Then, the surface temperature of drum 1 was raised by the hot water circulation device, and it maintained at the surface temperature of 90 degreeC.

On the other hand, 100 parts by mass of a chip of PVA (saponified product of a homopolymer of vinyl acetate) having a degree of saponification of 99.9 mol% and a degree of polymerization of 2,400 was immersed in 2,500 parts by mass of distilled water at 35°C for 24 hours, followed by centrifugal dehydration, and PVA water-containing chips got The volatile fraction in the PVA water-containing chip was 70 mass%. To 333 parts by mass of the PVA water-containing chip (100 parts by mass in terms of dry PVA), 12 parts by mass of glycerin and 0.3 parts by mass of a surfactant (containing 95 mass% of diethanolamide lauric acid) were added, and then mixed well to obtain a mixture. And this was heat-melted by the twin screw extruder with a vent with a maximum temperature of 130 degreeC. After cooling the obtained molten PVA to 100°C with a heat exchanger, it is extruded from a coat hanger die having a width of 900 mm on the drum 1 having a surface temperature of 90°C, and further passed through a hot air drying furnace and dried It was made and the width direction both ends (edge part) was cut, and the long PVA film of width 0.7m was manufactured continuously. In addition, the film-forming speed|rate was 8 m/min. The PVA film (60 m in thickness, 12,000 m in length) after film formation was stabilized was continuously wound on a cylindrical core made of aluminum having a diameter of 6 inches to obtain a film roll.

When the above-mentioned method evaluated the wrinkles (wrinkle which generate|occur|produces when winding up a PVA film) of the obtained film roll, it was A rank. In addition, as a result of measuring the average square roughness of the PVA film by the above method using the PVA film unwound from the obtained film roll, the mean square roughness in the surface on the side in contact with the surface of drum 1 is 4.1 nm, The mean square roughness in the other surface was 1.9 nm. The difference between the two was calculated to be 2.2 nm.

The PVA film unwound from the said film roll was processed continuously in order of preliminary|backup swelling, dyeing|staining, a fixed process, uniaxial stretching, washing|cleaning, and drying, and the polarizing film was produced. That is, the PVA film was pre-swelled by immersing it in water at 30°C for 60 seconds, followed by immersion in an aqueous solution (dye bath) at 35°C having an iodine concentration of 0.4 g/L and a potassium iodide concentration of 40 g/L for 110 seconds for dyeing. Then, it is immersed for 90 second in a 30 degreeC aqueous solution (fixed treatment bath) with a boric acid concentration of 30 g/L, a fixed process is performed, and also it extends|stretches longitudinally in 50 degreeC aqueous solution (stretching bath) of 4% of boric acid concentration. Uniaxial stretching was performed at a magnification of 5 times. Then, it was immersed for 10 second in the 30 degreeC aqueous solution (washing bath) of 15 g/L of boric-acid density|concentration, it wash|cleaned, it was made to hot-air-dry at 55 degreeC, and it was set as the polarizing film. In addition, the angle between the liquid level of the cleaning bath and the film surface when exiting the cleaning bath, which is the last treatment bath before entering the drying process, is set to 60° by changing the position of the guide roll, and the upper side of the film at that time It was made so that it might become the surface which had a smaller square mean roughness in the PVA film used by a surface.

As a result of having evaluated the dyeing nonuniformity of the obtained polarizing film by said method, it was A rank. Moreover, as a result of having evaluated the foreign material of the obtained polarizing film by said method, it was A rank.

[Example 9]

Except having used the drum 2 instead of the drum 1, it carried out similarly to Example 8, the PVA film was manufactured continuously, and it was set as the film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 2 after the buffing was measured by the above method, and as a result, it was 0.37 pieces/mm 2 .

When the above-mentioned method evaluated the wrinkles (wrinkle which generate|occur|produces when winding up a PVA film) of the obtained film roll, it was B rank. In addition, as a result of measuring the average square roughness of the PVA film by the above method using the PVA film unwound from the obtained film roll, the mean square roughness in the surface on the side in contact with the surface of drum 2 is 6.7 nm, The mean square roughness in the other surface was 2.0 nm. The difference between the two was calculated to be 4.7 nm.

About the PVA film unwound from said film roll, it carried out similarly to Example 8, and produced the polarizing film. As a result of having evaluated the dyeing|staining nonuniformity of the obtained polarizing film by said method, it was B rank. Moreover, as a result of having evaluated the foreign material of the obtained polarizing film by said method, it was B rank.

[Comparative Example 5]

Except having used the drum 3 instead of the drum 1, it carried out similarly to Example 8, the PVA film was manufactured continuously, and it was set as the film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 3 after the buffing was measured by the above method, and as a result, it was 0.73 pieces/mm 2 .

When the above-mentioned method evaluated the wrinkles (wrinkle which generate|occur|produces when winding up a PVA film) of the obtained film roll, it was A rank. In addition, as a result of measuring the average square roughness of the PVA film by the above method using the PVA film unwound from the obtained film roll, the mean square roughness in the surface on the side in contact with the surface of drum 3 is 28.3 nm, The mean square roughness in the other surface was 2.6 nm. The difference between the two was calculated to be 25.7 nm.

About the PVA film unwound from said film roll, it carried out similarly to Example 8, and produced the polarizing film. As a result of having evaluated the dyeing|staining unevenness of the obtained polarizing film by said method, it was C rank. Moreover, when the above-mentioned method evaluated the foreign material of the obtained polarizing film, it was C rank.

[Comparative Example 6]

Except having used the drum 4 instead of the drum 1, it carried out similarly to Example 8, the PVA film was manufactured continuously, and it was set as the film roll. ^{Further, the number of cracks having an area of 200 µm 2} or more on the surface (peripheral surface) of the drum 4 after the buffing was measured by the above method, and as a result, it was 0.15 pieces/mm 2 .

When the above-mentioned method evaluated the wrinkles (wrinkle which generate|occur|produces when winding up a PVA film) of the obtained film roll, it was C rank. In addition, as a result of measuring the average square roughness of the PVA film by the above method using the PVA film unwound from the obtained film roll, the mean square roughness in the surface on the side in contact with the surface of the drum 4 is 2.8 nm, The mean square roughness in the other surface was 2.6 nm. The difference between the two was calculated to be 0.2 nm.

About the PVA film unwound from said film roll, it carried out similarly to Example 8, and produced the polarizing film. As a result of having evaluated the dyeing nonuniformity of the obtained polarizing film by said method, it was A rank. Moreover, as a result of having evaluated the foreign material of the obtained polarizing film by said method, it was A rank.

[Example 10]

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 level of the cleaning bath and the film surface when exiting the cleaning bath was changed from 60° to 45° . As a result of having evaluated the dyeing nonuniformity of the obtained polarizing film by said method, it was A rank. Moreover, as a result of having evaluated the foreign material of the obtained polarizing film by said method, it was B rank.

[Comparative Example 7]

The same as in Example 8 except that the film roll obtained in Example 8 was used and the surface on the upper side of the film when exiting the washing bath was changed to be the surface having the larger mean square roughness of the used PVA film. to prepare a polarizing film. As a result of having evaluated the dyeing nonuniformity of the obtained polarizing film by said method, it was A rank. Moreover, when the above-mentioned method evaluated the foreign material of the obtained polarizing film, it was C rank.

[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 level and the film surface of the cleaning bath when exiting the cleaning bath was changed from 60° to 25° . As a result of having evaluated the dyeing nonuniformity of the obtained polarizing film by said method, it was A rank. Moreover, when the above-mentioned method evaluated the foreign material of the obtained polarizing film, it was C rank.

[Comparative Example 9]

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 level and the film surface of the cleaning bath when exiting the cleaning bath was changed from 60° to 88° . As a result of having evaluated the dyeing|staining nonuniformity of the obtained polarizing film by said method, it was A rank. Moreover, when the above-mentioned method evaluated the foreign material of the obtained polarizing film, it was C rank.

Claims (24)

A film roll in which a polyvinyl alcohol-based polymer film having a length of 6,000 m or more is continuously wound, the polyvinyl alcohol-based polymer film with respect to defects ^{dented from the film surface, having an area of 400 µm 2 or more and a depth of 0.3 µm or more} The number of defects in the winding end portion of the polyvinyl alcohol-based polymer film relative to the number of defects in the winding start portion of the film roll is 1.4 times or less, and the number of defects is 0.25 pieces/m 2 or less. delete The method of claim 1,
A film roll wherein the number of defects is 0.15 pieces/m 2 or less. The method according to claim 1 or 3,
A film roll having a polymerization degree of 3,000 or more and 10,000 or less of the polyvinyl alcohol-based polymer contained in the polyvinyl alcohol-based polymer film. The method according to claim 1 or 3,
The film roll comprising defects, wherein the defects are at regular intervals in the longitudinal direction of the film and present at the same positions in the width direction of the film. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete