WO2017038955A1

WO2017038955A1 - Polyvinyl alcohol film roll

Info

Publication number: WO2017038955A1
Application number: PCT/JP2016/075731
Authority: WO
Inventors: 佐藤　直人; 弘治笹井; 秀行秦; 正次亀岡; 高士 ▲はま▼岡; 翔太山本
Original assignee: 株式会社クラレ
Priority date: 2015-09-02
Filing date: 2016-09-01
Publication date: 2017-03-09
Also published as: CN107922142A; TW201718732A; JP6815321B2; TWI666238B; CN107922142B; KR102375984B1; JPWO2017038955A1; KR20200003279A; KR20180039151A

Abstract

Provided are: a roll obtained by winding a PVA film that is at least 2,000 m long and no more than 45 μm thick, wherein the average gap between adjacent films is no more than 5 μm; and a method for manufacturing a roll obtained by winding a PVA film that is at least 2,000 m long and no more than 45 μm thick, wherein a touch-winding scheme is employed, the pressure between a film roll and a contact roll is 3-30N per meter of axial length of the film roll, and the winding speed is no more than 30 m/min. Thereby provided is a PVA film roll that has excellent external appearance and does not readily become wrinkled or eccentric even when the PVA film is thin and has a high winding length.

Description

Polyvinyl alcohol film roll

The present invention relates to a roll of a polyvinyl alcohol film having a good appearance and a method for producing the roll.

A polarizing plate, which is a basic component of a liquid crystal display (LCD) such as a liquid crystal television or a liquid crystal monitor, is generally dyed on a polyvinyl alcohol film (hereinafter, “polyvinyl alcohol” may be abbreviated as “PVA”). By producing a polarizing film by uniaxial stretching and further fixing treatment with a boron compound or the like as required, and then bonding a protective film such as a cellulose triacetate (TAC) film on the surface of the obtained polarizing film Manufactured.

In recent years, LCDs have become larger and thinner. As a means for achieving the thinning of the LCD, a method of thinning the glass used therefor can be considered. When thinning glass, it is necessary to reduce the contraction stress of the polarizing plate by reducing the thickness of the polarizing plate. Therefore, it is required to produce a thin polarizing film using a thinner PVA film (see, for example, Patent Document 1).

The PVA film is usually stored or transported in the form of a roll in which a long PVA film is wound around a cylindrical core (see, for example, Patent Document 2). In order to efficiently and continuously produce a polarizing plate with a large area and excellent optical performance uniformity, a roll of a PVA film having a wider width, a longer winding length and excellent quality is required. ing. Patent Document 2 discloses a method of passing a PVA film between a guide roll attached to a cylindrical core tube and the core tube and winding the PVA film around the cylindrical core tube, the guide roll and the cylinder A winding method is described in which the guide core and the cylindrical core tube are in contact with each other via the PVA film, in a non-contact state in which the cylindrical core tube is installed at a distance. However, when the PVA film is thinner and the winding length is longer, a slight wrinkle or eccentricity in which the center of gravity of the roll is shifted occurs, and a roll having a good appearance shape cannot be obtained. When such a roll of PVA film is used as a raw fabric, there is a problem that the uniformity of the PVA film is impaired due to fluctuations occurring when the PVA film is unwound.

International Publication No. 2014/050697 JP 2004-106376 A

The present invention has been made to solve the above-described problems, and provides a roll of a PVA film having a good appearance shape that is less likely to cause wrinkles and eccentricity even when the PVA film is thin and the winding length is long. The purpose is to do.

As a result of intensive studies to solve the above problems, the present inventors have solved the above problems by setting the interval (the thickness of the air layer) between the PVA films wound around the roll to a specific range. As a result of further investigation based on this finding, the present invention was completed.

That is, the present invention
[1] A roll formed by winding a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more, and an average interval between adjacent films is 5 μm or less;
[2] The roll of the above [1], wherein the width of the PVA film is 2 m or more;
[3] The roll of [1] or [2] above, wherein the content of the plasticizer in the polyvinyl alcohol film is 1 to 30% by mass;
[4] The roll according to any one of [1] to [3], wherein the content of the surfactant in the polyvinyl alcohol film is 0.01 to 1.0% by mass;
[5] The roll according to any one of the above [1] to [4], wherein the width of the polyvinyl alcohol film is 2 m or more;
[6] The roll according to any one of [1] to [5] above, wherein the PVA film is a raw film for producing an optical film;
[7] The roll of the above [6], wherein the optical film is a polarizing film;
[8] A method for producing a roll in which a polyvinyl alcohol film having a thickness of 45 μm or less and a length of 2,000 m or more is wound,
(A) In the winding process of the polyvinyl alcohol film, a contact roll disposed substantially parallel to the axial direction of the film roll is brought into contact with the outer peripheral surface of the film roll formed from the already wound polyvinyl alcohol film. While winding the polyvinyl alcohol film,
(B) The pressure between the film roll and the contact roll is 3 to 30 N per 1 m of the axial length of the film roll,
(C) The winding speed is 30 m / min or less,
Production method;
[9] The production method of the above [8], wherein the winding tension is 80 N or less per 1 m in the axial direction of the film roll;
[10] The above-mentioned [8] or [9], wherein the parallelism A between the film roll axis and the contact roll axis, obtained from the distance between the film roll axis and the contact roll axis, is 0.7 mm or less. Production method;
[11] The parallelism B between the axis of the film roll and the axis of the contact roll when the film roll and the contact roll are viewed from the horizontal direction is obtained from the level of the axis of the film roll and the level of the axis of the contact roll. Any one of the above-mentioned [8] to [10], which is 0.2 mm or less;
[12] The production method according to any one of the above [8] to [11], wherein an average distance between adjacent films in a roll formed by winding a polyvinyl alcohol film is 5 μm or less;
About.

According to the present invention, a roll of a PVA film having a good appearance shape even when the PVA film is thin and the winding length is long is provided. According to the manufacturing method of the present invention, such a roll is efficiently manufactured.

It is the schematic which shows an example of a touch winding system. It is the schematic which shows an example of a near winding system. In FIG. 1, it is an example of the schematic diagram of the film roll 1 and the contact roll 2 seen from the direction 11 of the tangent 10 of the contact roll 2 in the position where the contact roll 2 contacts the film roll 1. In FIG. 1, it is an example of the schematic diagram of the film roll 1 and the contact roll 2 seen from the horizontal direction 12.

Hereinafter, the present invention will be described in detail. The roll of the present invention is formed by winding a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more. And in the roll of this invention, the average space | interval between adjacent films is 5 micrometers or less.

When winding the PVA film to obtain the roll of the present invention, it is preferable to wind the PVA film around a cylindrical core from the viewpoint of the quality and handleability of the roll obtained. There is no restriction | limiting in particular in the kind of cylindrical core, For example, a metal thing, a plastic thing, a paper thing, a wooden thing etc. are mentioned. Also, composite cores such as those using both metal and plastic, those using both metal and paper, and those using both plastic and paper can also be used. Among these, the cores made of metal and / or plastic have a high strength and the effects of the present invention are more remarkably produced, and there is little dust generation that tends to be a problem in the production of optical films such as polarizing films. A metal core is more preferable because it is less susceptible to wear and the like even after repeated use. The proportion of the mass of the metal and plastic with respect to the total mass of the cylindrical core is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 95% by mass or more. The amount is preferably 100% by mass.

Examples of the metal include iron, stainless steel, and aluminum. One of these may be used alone, or two or more may be used in combination. Among these, aluminum and iron are preferable from the viewpoints of strength, lightness, and price.

Examples of the plastic include polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate, polyamide, epoxy resin, polyurethane, polyurea, and silicone resin. One of these is used alone. Moreover, you may use 2 or more types together. Of these, polyvinyl chloride is preferred. The plastic is also preferably a fiber reinforced plastic (FRP) such as a carbon fiber reinforced plastic from the viewpoint of strength and the like.

The length of the cylindrical core is not particularly limited, but it is preferably 5 to 100 cm longer than the width of the PVA film to be wound from the viewpoint of handleability and the like, and is preferably 10 to 45 cm. Is more preferable, and it is more preferable that the length is within a range of 15 to 30 cm.

The diameter of the cylindrical core is not particularly limited, but the outer diameter is preferably in the range of 50 to 800 mm, more preferably in the range of 80 to 500 mm, from the viewpoints of strength and handleability. The thickness is more preferably in the range of 100 to 300 mm, and particularly preferably in the range of 150 to 250 mm. The thickness of the cylindrical core is preferably in the range of 2 to 50 mm, more preferably in the range of 3 to 20 mm, and more preferably in the range of 4 to 10 mm from the viewpoints of strength, handleability, and the like. More preferably, it is within.

PVA constituting the PVA film used in the present invention includes, for example, unmodified PVA obtained by saponifying a polyvinyl ester obtained by polymerizing vinyl ester, and a modified copolymer obtained by graft copolymerization with a main chain of PVA. PVA, a modified polyvinyl ester obtained by saponifying a modified polyvinyl ester obtained by copolymerizing a vinyl ester and a comonomer, a part of hydroxyl groups of the modified PVA, unmodified PVA or modified PVA is cross-linked with aldehydes such as formalin, butyraldehyde, benzaldehyde, etc. A polyvinyl acetal resin etc. can be mentioned. When the PVA constituting the PVA film is a modified PVA, the amount of modification in the PVA is preferably 15 mol% or less, and more preferably 5 mol% or less.

Examples of the vinyl ester used in the production of PVA include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valelate, vinyl pivalate, vinyl laurate, vinyl stearate, vinyl benzoate, and versatic. A vinyl acid etc. can be mentioned. These vinyl esters can be used alone or in combination. Of these vinyl esters, vinyl acetate is preferred from the viewpoint of productivity.

Examples of the above-mentioned comonomer include olefins having 2 to 30 carbon atoms such as ethylene, propylene, 1-butene and isobutene (α-olefin and the like); acrylic acid or a salt thereof; methyl acrylate, ethyl acrylate, Acrylic esters such as n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, etc. For example, acrylic acid having 1 to 18 carbon atoms of acrylic acid); methacrylic acid or a salt thereof; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i -Butyl, tert-butyl methacrylate, methacrylate Methacrylic acid esters such as 2-ethylhexyl phosphate, dodecyl methacrylate, octadecyl methacrylate (for example, alkyl esters of 1 to 18 carbon atoms of methacrylic acid); acrylamide; N-methylacrylamide, N-ethylacrylamide, N, N Acrylamide derivatives such as dimethyl acrylamide, diacetone acrylamide, acrylamide propane sulfonic acid or salts thereof, acrylamide propyl dimethylamine or salts thereof, N-methylol acrylamide or derivatives thereof; methacrylamide; N-methyl methacrylamide, N-ethyl methacrylamide , Methacrylamide propane sulfonic acid or its salt, methacrylamide propyl dimethylamine or its salt, N-methylol methacrylamide or its derivative Methacrylamide derivatives such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone and other N-vinylamides; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i -Vinyl ethers such as butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; Nitriles such as acrylonitrile and methacrylonitrile; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride; Acetic acid Allyl compounds such as allyl and allyl chloride; unsaturated dicarboxylic acids such as maleic acid and itaconic acid, derivatives thereof such as salts or esters thereof; vinylsilyl such as vinyltrimethoxysilane Compound; isopropenyl acetate; an unsaturated sulfonic acid or its derivatives. These comonomers may be used individually by 1 type, or may use 2 or more types together. Of these comonomers, α-olefins are preferable, and ethylene is particularly preferable.

The degree of polymerization of PVA is preferably 1,000 or more, more preferably 1,500 or more, and more preferably 2,000 or more, from the viewpoint of the polarizing performance and durability of the obtained polarizing film. Further preferred. Moreover, from the viewpoint of ease of production for obtaining a homogeneous PVA film, stretchability, etc., the degree of polymerization of PVA is preferably 8,000 or less, and more preferably 6,000 or less. The polymerization degree of PVA in this specification means an average polymerization degree measured according to the description of JIS K6726-1994, and is obtained from the intrinsic viscosity measured in water at 30 ° C. after re-saponifying and purifying PVA. .

The saponification degree of PVA is preferably 95 mol% or more, more preferably 98 mol% or more, and more preferably 99 mol% or more from the viewpoint of the polarizing performance and durability of the obtained polarizing film. Further preferred. The saponification degree of PVA in this specification is the number of moles of the vinyl alcohol unit relative to the total number of moles of structural units (typically vinyl ester units) and vinyl alcohol units that can be converted to vinyl alcohol units by saponification. The ratio (mol%) which occupies. The saponification degree of PVA can be measured according to the description of JIS K6726-1994.

1 type of PVA may be sufficient as PVA which comprises a PVA film, and 2 or more types of PVA from which one or two or more in a polymerization degree, a saponification degree, a modification degree, etc. differ may be sufficient. The PVA content in the PVA film is preferably in the range of 50 to 100% by mass, more preferably in the range of 80 to 100% by mass, and in the range of 85 to 100% by mass. Further preferred.

Mechanical properties such as impact strength can be improved, process passability and stretchability during secondary processing can be improved, and the roll of the present invention can be obtained more efficiently. The film preferably contains a plasticizer. Preferred plasticizers include polyhydric alcohols, and specific examples include ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane. The PVA film can contain one or more of these plasticizers. Among these plasticizers, one or more of glycerin, diglycerin, and ethylene glycol are preferably used from the viewpoint of stretchability improvement effect when the PVA film is stretched and used, and glycerin is more preferable. Preferably used.

The content of the plasticizer in the PVA film is preferably in the range of 1 to 30% by mass. When the content of the plasticizer in the PVA film is less than 1% by mass, since the flexibility of the film is insufficient, there is a problem that the film is broken at the time of winding or the stretchability at the time of producing the polarizing plate is poor. From such a viewpoint, the content is more preferably 5% by mass or more, and further preferably 10% by mass or more. In addition, when the content of the plasticizer in the PVA film exceeds 30% by mass, the bleed out occurs during storage of the roll, and the uniformity of the physical properties may be impaired in the plane of the PVA film, The problem that film sticking easily occurs. From such a viewpoint, the content is more preferably 20% by mass or less, and further preferably 15% by mass or less.

The PVA film preferably contains a surfactant from the viewpoints of handleability and improvement in peelability from a film forming apparatus when the PVA film is produced. There is no restriction | limiting in particular in the kind of surfactant, Anionic surfactant, a nonionic surfactant, etc. are mentioned.

Examples of the anionic surfactant include carboxylic acid types such as potassium laurate; sulfate ester types such as octyl sulfate; sulfonic acid types such as dodecylbenzene sulfonate and the like.

Examples of nonionic surfactants include alkyl ether types such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; alkyl phenyl ether types such as polyoxyethylene octyl phenyl ether; alkyl ester types such as polyoxyethylene laurate. Alkylamine type such as polyoxyethylene lauryl amino 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. Examples include alkanolamide type; allyl phenyl ether type such as polyoxyalkylene allyl phenyl ether.

The PVA film can contain one or more of these surfactants. Among these surfactants, nonionic surfactants are preferred because of their excellent effect of reducing film surface abnormalities during film formation, and alkanolamide type surfactants are particularly preferred, and aliphatic carboxylic acids (for example, Further, dialkanolamides (for example, diethanolamide and the like) of C8-30 saturated or unsaturated aliphatic carboxylic acid and the like are more preferable.

In the present invention, the surfactant content in the PVA film is preferably in the range of 0.01 to 1% by mass. When there is too little content rate of surfactant, the handleability of a PVA film and the peelability from the film forming apparatus at the time of manufacturing a PVA film may deteriorate more, or blocking may generate | occur | produce. From this viewpoint, the content of the surfactant is more preferably 0.02% by mass or more, and further preferably 0.05% by mass or more. On the other hand, when the content of the surfactant is too high, the film is bleed out and the uniformity of the film is impaired, so that the obtained polarizing plate is likely to have optical unevenness or the transparency of the film is deteriorated. From this viewpoint, the content of the surfactant is more preferably 0.5% by mass or less, and further preferably 0.3% by mass or less.

The PVA film further contains other components such as antioxidants, ultraviolet absorbers, lubricants, colorants, antiseptics, antifungal agents, other polymer compounds other than those described above, and moisture as necessary. May be. The PVA film can contain one or more of these other components.

The production method of the PVA film is not particularly limited, and a production method in which the thickness and width of the film after film formation are more uniform can be preferably adopted. For example, the above-described PVA constituting the PVA film, and further if necessary A film-forming stock solution in which one or more of plasticizers, surfactants and the above-mentioned other components are dissolved in a liquid medium, PVA, and further plasticizers, surfactants, and other It can be produced using a film-forming stock solution containing one or more of components and liquid medium and in which PVA is melted. When the film-forming stock solution contains at least one of a plasticizer, a surfactant and the other components, it is preferable that these components are mixed uniformly.

Examples of the liquid medium used for the preparation of the membrane forming stock solution include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol. , Trimethylolpropane, ethylenediamine, diethylenetriamine and the like, and one or more of them can be used. Among these, water and dimethyl sulfoxide are preferable, and water is more preferable.

The volatile fraction of the film-forming stock solution (the content ratio of volatile components such as liquid media removed by volatilization or evaporation during film-forming in the film-forming stock solution) depends on the degree of polymerization of PVA, the film-forming method, the film-forming conditions, However, it is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, particularly preferably 40% by mass or more, and 95% by mass. It is preferably at most mass%, more preferably at most 90 mass%, further preferably at most 85 mass%, particularly preferably at most 70 mass%. When the volatile fraction of the film-forming stock solution is above the above lower limit, the viscosity of the film-forming stock solution does not become too high, and filtration and defoaming are smoothly performed during preparation of the film-forming stock solution, and there are few foreign matters and defects. Is easy to manufacture. On the other hand, when the volatile fraction of the film-forming stock solution is not more than the above upper limit, the concentration of the film-forming stock solution does not become too low, and the production of an industrial PVA film becomes easy.

Examples of the film forming method for forming a PVA film using the above-described film forming stock solution include a cast film forming method, an extrusion film forming method, a wet film forming method, and a gel film forming method. These film forming methods may be used alone or in combination of two or more. Among these film forming methods, the cast film forming method and the extrusion film forming method are preferable from the viewpoint of obtaining a good PVA film.

As an example of a specific method for producing a PVA film, for example, a known film discharge device (film casting device) such as a T-shaped slit die, a hopper plate, an I-die, or a lip coater die is used. The film-forming stock solution is uniformly discharged or cast on the peripheral surface of the first heated heated roll (or belt) located on the most upstream side, and discharged or cast on the peripheral surface of the first roll (or belt). Evaporating and drying volatile components from one side of the cast film, followed by further drying on the circumference of one or more rotating heated rolls located downstream thereof, or A method of passing through a hot air drying apparatus can be preferably employed industrially. Drying with a heated roll and drying with a hot air dryer may be performed in an appropriate combination.

The thickness of the PVA film in the roll of the present invention needs to be 45 μm or less. When the thickness of the PVA film is 45 μm or less, a thin polarizing film can be produced efficiently. And a thin polarizing plate can be efficiently manufactured by using such a thin polarizing film. Conventionally, when the PVA film is thin and the winding length is long, there is a problem that slight wrinkles and eccentricity are generated and a roll having a good appearance shape cannot be obtained. On the other hand, according to the present invention, even when the PVA film is thin and the winding length is long, a roll of the PVA film having a good appearance shape that is less likely to cause wrinkles and eccentricity is obtained. Therefore, the effect of the present invention is remarkably exhibited when the thickness of the PVA film is 45 μm or less. From the above viewpoint, the thickness of the PVA film is preferably 40 μm or less, more preferably 35 μm or less, further preferably 30 μm or less, particularly preferably 25 μm or less, and 20 μm or less. Most preferred. On the other hand, if the thickness of the PVA film is too thin, secondary processing of a film that is processed into an optical film such as a polarizing film tends to be difficult. Therefore, the thickness is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, and particularly preferably 10 μm or more.

The winding length of the PVA film in the roll of the present invention, that is, the length of the PVA film to be wound is required to be 2,000 m or more. When the length of the PVA film is 2,000 m or more, even if the optical film such as a polarizing film to be manufactured has a large area, it is possible to efficiently and continuously manufacture a product having excellent optical performance uniformity. it can. Conventionally, when the PVA film is thin and the winding length is long, there is a problem that slight wrinkles and eccentricity are generated and a roll having a good appearance shape cannot be obtained. On the other hand, according to the present invention, even when the PVA film is thin and the winding length is long, a roll of the PVA film having a good appearance shape that is less likely to cause wrinkles and eccentricity is obtained. Therefore, the effect of the present invention is remarkably exhibited when the length of the PVA film is 2,000 m or more. From the above viewpoint, the length of the PVA film is preferably 3,000 m or more, more preferably 4,000 m or more, further preferably 5,000 m or more, and 8,000 m or more. It is particularly preferable that it is 12,000 m or more. Although there is no restriction | limiting in particular in the upper limit of the length of a PVA film, Since the roll of a PVA film with a more favorable external shape is easy to be obtained etc., the said length is preferably 30,000 m or less, and is 22,000 m or less. It is more preferable that The length of the PVA film may be 18,000 m or less, and further 15,000 m or less.

The width of the PVA film is not particularly limited, and can be, for example, 50 cm or more. By the way, normally, there exists a tendency for wrinkles and eccentricity to occur easily in the roll obtained as the width of the PVA film is wider. On the other hand, according to the present invention, since the occurrence of wrinkles and eccentricity is reduced even when the width of the PVA film is wide, the effect of the present invention is more remarkably exhibited in such a case. Further, by using a PVA film having a wide width, it is possible to produce a wide polarizing film that can cope with an increase in the screen size of the LCD. From these points, the width of the PVA film is preferably 2 m or more, more preferably 2.5 m or more, further preferably 2.7 m or more, particularly preferably 3 m or more. It may be 5 m or more. Although there is no restriction | limiting in particular in the upper limit of the width | variety of a PVA film, Since the roll of a PVA film with more favorable external appearance shape is easy to be obtained, the said width | variety is preferably 6 m or less, and more preferably is 5 m or less. More preferably, it is 4.2 m or less. From the point that a PVA film having a particularly excellent external shape can be obtained, it is preferably 4 m or less, and more preferably 3.8 m or less.

In the roll of the present invention, it is necessary that the average interval between adjacent films (between adjacent PVA films in the radial direction of the roll) is 5 μm or less. The average interval corresponds to the thickness of the air layer between the films. When the average interval is 5 μm or less, even when the PVA film is thin and the winding length is long, wrinkles and eccentricity are hardly generated, and a roll having a good appearance shape can be obtained. From such a viewpoint, the average interval is preferably 4.9 μm or less, more preferably 4.5 μm or less, further preferably 4.2 μm or less, 4 μm or less, and further 3.8 μm. It may be the following. Moreover, when the average space | interval between adjacent films is less than 2 micrometers, blocking arises and a fluctuation | variation generate | occur | produces at the time of unwinding of a PVA film, or external appearance abnormalities, such as a wrinkle, generate | occur | produce in a film by winding and narrowing of a PVA film roll It is easy to cause the problem that uniformity is impaired. From such a viewpoint, the average interval is preferably 2 μm or more, more preferably 2.5 μm or more, further preferably 3 μm or more, and particularly preferably 3.5 μm or more.

The average distance between the adjacent films can be determined by the following method. That is, an average between the adjacent films in an outer diameter H (m) roll in which a PVA film having a length L (m) and a thickness M (μm) is wound around a cylindrical core having an outer diameter D (m). The interval N (μm) is given by the following formula:
N = {(π / 4) (H ² −D ² ) / L} × 10 ⁶ −M
Can be calculated.

Although there is no restriction | limiting in particular in the manufacturing method of the roll of this invention, Since the said roll can be manufactured efficiently according to the manufacturing method of the following this invention, it is preferable. That is, the manufacturing method of the present invention is a manufacturing method of a roll formed by winding a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more,
(A) In the winding process of the PVA film, a contact roll disposed substantially parallel to the axial direction of the film roll on the outer peripheral surface of the film roll (film-like portion) formed from the already wound PVA film The PVA film is wound up while contacting
(B) The pressure between the film roll and the contact roll is 3 to 30 N per 1 m of the axial length of the film roll,
(C) It is a manufacturing method whose winding speed is 30 m / min or less.

In the production method of the present invention, as the PVA film used for producing the roll, those described above as the PVA film used for producing the roll of the present invention can be used.

In the production method of the present invention, in the winding process of the PVA film, a contact roll disposed substantially parallel to the axial direction of the film roll is provided on the outer peripheral surface of the film roll formed by the already wound PVA film. A touch winding method that winds the PVA film while making contact is adopted. FIG. 1 is a schematic view showing an example of the touch winding method. As shown in FIG. 1, a contact roll 2 disposed substantially parallel to the axial direction of the film roll 1 is in direct contact with the outer peripheral surface of the film roll 1 formed from the already wound PVA film 3. A roll is manufactured by further winding the PVA film 3 in a state. As the contact roll 2 to be used, one that is longer than the axial length of the film roll 1 can be used. In the position 5 where the PVA film 3 is wound around the film roll 1, the film roll 1 and the contact roll 2 are preferably in contact with each other over the entire axial direction of the film roll 1. As a method different from the touch winding method, a near winding method as shown in a schematic diagram in FIG. 2 is known. As shown in FIG. 2, in the near winding method, when the PVA film 3 is wound, a space (gap) is formed between the outer peripheral surface of the film roll 1 formed from the already wound PVA film and the contact roll 2. Is held.

The length of the contact roll 2 is not particularly limited, but is preferably longer than the width of the film roll 1 within a range of 3 to 200 cm, more preferably within a range of 5 to 100 cm, and more preferably within a range of 10 to 50 cm. It is more preferable that the length is long.

The diameter of the contact roll 2 is not particularly limited, but from the viewpoint of strength, handleability, etc., the outer diameter is preferably in the range of 50 to 1000 mm, more preferably in the range of 75 to 800 mm. More preferably, it is within the range of 100 to 500 mm, and particularly preferably within the range of 125 to 350 mm. The material of the surface layer of the contact roll 2 is not particularly limited, and examples thereof include rubber, resin, metal, etc. Among them, rubber is preferable.

In the production method of the present invention, when the PVA film 3 is wound, the pressure between the film roll 1 and the contact roll 2 (pressure for pressing the contact roll 2 against the film roll 1) is the length of the film roll 1 in the axial direction. The range is 3 to 30 N per meter. Hereinafter, the pressure may be referred to as “winding contact pressure”, and “N / m” may be used as a unit for indicating the pressure per 1 m in the axial length of the film roll. By setting the winding contact pressure within the above range, the roll of the present invention can be produced efficiently. From this viewpoint, the winding contact pressure is preferably 20 N / m or less, more preferably 10 N / m or less, and still more preferably 8 N / m or less. From the viewpoint of more efficiently producing the roll of the present invention, it is preferably 3.5 N / m or more, and more preferably 4 N / m or more.

In the production method of the present invention, the winding speed when winding the PVA film 3 is 30 m / min or less. By setting the winding speed to 30 m / min or less, the roll of the present invention can be produced efficiently. From this viewpoint, the winding speed is preferably 25 m / min or less. From the viewpoint of more efficiently producing the roll of the present invention, the winding speed is preferably 9 m / min or more, and more preferably 15 m / min or more.

In the production method of the present invention, the winding tension when winding the PVA film 3 (the tension applied in the length direction of the PVA film 3 when winding the PVA film) is formed from the already wound PVA film. It is preferable to set it as 80 N or less per 1 m of axial lengths of the film roll 1. Hereinafter, “N / m” may be used as a unit for indicating the winding tension per 1 m in the axial direction of the film roll 1. By setting the winding tension within the above range, the roll of the present invention can be produced more efficiently. From this viewpoint, the winding tension is more preferably 75 N / m or less, and further preferably 70 N / m or less. From the viewpoint of more efficiently producing the roll of the present invention, the winding tension is preferably 20 N / m or more, more preferably 40 N / m or more, and 45 N / m or more. More preferably, it is particularly preferably 50 N / m or more.

FIG. 3 is an example of a schematic diagram of the film roll 1 and the contact roll 2 viewed from the direction 11 of the tangent line 10 of the contact roll 2 at a position where the contact roll 2 contacts the film roll 1 in FIG. In the production method of the present invention, the parallelism A between the axis of the film roll 1 and the axis of the contact roll 2, which is obtained from the distance between the axis of the film roll 1 and the axis of the contact roll 2, is preferably 0.7 mm or less. Thereby, in the position 5 where the PVA film 3 is wound around the film roll 1, the film roll 1 and the contact roll 2 are easy to contact over the entire axial direction of the film roll 1. A roll can be manufactured more efficiently. The parallelism A is more preferably 0.5 mm or less, and further preferably 0.2 mm or less. In the present invention, the parallelism A is determined by the distance ba from the one end b of the shaft 7 of the contact roll 2 to the shaft 6 of the film roll 1 and the axis of the film roll 1 from the other end b ′ of the shaft 7 of the contact roll 2. The difference of distance b′−a ′ up to 6 is shown. One end b of the shaft 7 of the contact roll 2 is located closest to the end portion 8 of the PVA film 3, and the other end b ′ is located closest to the end portion 9 of the PVA film 3. The distance b-a and the distance b'-a 'can be measured using a dial gauge.

FIG. 4 is an example of a schematic view of the film roll 1 and the contact roll 2 viewed from the horizontal direction 12 in FIG. In the production method of the present invention, the axis of the film roll 1 when the film roll 1 and the contact roll 2 are viewed from the horizontal direction, which is obtained from the level of the axis of the film roll 1 and the level of the axis of the contact roll 2. The parallelism B of the axis of the contact roll 2 is preferably 0.2 mm or less. Thereby, in the position 5 where the PVA film 3 is wound around the film roll 1, the film roll 1 and the contact roll 2 are easy to contact over the entire axial direction of the film roll 1. A roll can be manufactured more efficiently. The parallelism B is more preferably 0.15 mm or less, and further preferably 0.1 mm or less. The parallelism B in the present invention will be specifically described below. The axis 7 of the contact roll 2 is projected onto a plane including the axis 6 of the film roll 1 and perpendicular to the horizontal plane. Then, on the projection plane, a distance dc from one end d of the shaft 7 of the contact roll 2 to the shaft 6 of the film roll 1 and from the other end d ′ of the shaft 7 of the contact roll 2 to the shaft 6 of the film roll 1 The difference in distance d′−c ′ is defined as parallelism B. One end d of the shaft 7 of the contact roll 2 is positioned closest to the end portion 8 of the PVA film 3, and the other end d ′ is positioned closest to the end portion 9 of the PVA film 3. The parallelism B can be obtained by measuring the horizontal degrees in the axial direction of the film roll 1 and the contact roll 2 using a level.

In the roll thus obtained, the average distance between adjacent films is preferably 5 μm or less. When the average interval is 5 μm or less, even when the PVA film is thin and the winding length is long, wrinkles and eccentricity are hardly generated, and a roll having a good appearance shape can be obtained. According to the manufacturing method of the present invention, the average interval can be easily controlled. The average interval is preferably 4.9 μm or less, more preferably 4.5 μm or less, still more preferably 4.2 μm or less, even 4 μm or less, and even 3.8 μm or less. Good. On the other hand, the average interval is preferably 2 μm or more, more preferably 2.5 μm or more, further preferably 3 μm or more, and particularly preferably 3.5 μm or more.

The use of the PVA film in the roll of the present invention is not particularly limited. For example, a film for drug packaging, a base film for hydraulic transfer, a base film for embroidery, a release film for artificial marble molding, a film for seed packaging, a waste container It can be used for various water-soluble films such as a bag film. According to the present invention, even when the PVA film is thin and the winding length is long, a roll having a good appearance shape that is less likely to cause wrinkles and eccentricity is provided. If such a roll is used, an optical film having excellent optical performance uniformity can be efficiently and continuously manufactured even in a large area. Therefore, it is preferable to use the PVA film as a raw film for producing an optical film. Examples of such an optical film include a polarizing film and a retardation film, and a polarizing film is preferable. Such an optical film can be produced, for example, by applying a treatment such as uniaxial stretching using the above PVA film.

The method for producing a polarizing film using a PVA film is not particularly limited, and any conventionally known method may be adopted. As such a method, for example, the PVA film unwound from the roll of the present invention is used for dyeing and uniaxial stretching, or the PVA film containing the dye unwound from the roll of the present invention is used. The method of giving uniaxial stretching is mentioned. As a more specific method for producing the polarizing film, the PVA film unwound from the roll of the present invention is swelled, dyed, uniaxially stretched, and if necessary, a crosslinking treatment, a fixing treatment, Examples of the method include drying and heat treatment. In this case, the order of each treatment such as swelling, dyeing, crosslinking treatment, uniaxial stretching, and fixing treatment is not particularly limited, and one or two or more treatments can be performed simultaneously. Also, one or more of each process can be performed twice or more.

The produced polarizing film is usually used in the form of a polarizing plate by laminating a protective film that is optically transparent and has mechanical strength on one or both sides. As the protective film, a cellulose triacetate (TAC) film, a cycloolefin polymer (COP) film, an acetic acid / cellulose butyrate (CAB) film, an acrylic film, a polyester film, or the like is used. Examples of the adhesive for bonding include PVA adhesives and urethane adhesives, among which PVA adhesives are suitable.

The polarizing plate obtained as described above can be used as an LCD component after being coated with an acrylic adhesive or the like and bonded to a glass substrate. At the same time, it may be bonded to a retardation film, a viewing angle improving film, a brightness improving film, or the like.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Evaluation of appearance shape]
The appearance of the roll was evaluated according to the following criteria.
A: No wrinkles or eccentricity is generated and the appearance is good B: Only slight wrinkles are observed, but no eccentricity is generated and the appearance is good C: slight wrinkles and deviation A wick has occurred and the external shape is poor.

[Evaluation of optical unevenness]
Sample films of 15 cm × 15 cm were collected from the center and both ends of the film rolls obtained in the following examples and comparative examples. A polarizing film was produced by performing a swelling process, a dyeing process, a crosslinking process, a stretching process, a fixing process process, and a drying process on the PVA film. Four sample films were attached to a stretching jig. While immersed in water at a temperature of 30 ° C. for 1 minute, it was uniaxially stretched (first-stage stretching) in the length direction (MD) to 2.2 times the original length. Thereafter, while being immersed in a dyeing bath at a temperature of 30 ° C. containing 0.03% by mass of iodine and 3.0% by mass of potassium iodide for 2 minutes, the length is increased to 3.2 times the original length. Uniaxial stretching (second stage stretching) was performed in the longitudinal direction (MD). Next, while being immersed in a crosslinking bath containing 30% by weight of boric acid and 3.0% of potassium iodide at a temperature of 30 ° C. for 2 minutes, the length is 3.6 times the original length. Uniaxial stretching (third stage stretching) was performed in the direction (MD). Furthermore, uniaxial stretching (fourth-stage stretching) was performed while dipping in a stretching bath at a temperature of 55 ° C. containing 4.0% by mass of boric acid and 5.0% by mass of potassium iodide. Two of the films were removed from the stretching bath, which was not cut when two of the films were cut. Thereafter, the film was washed by immersing in a fixed treatment bath at a temperature of 22 ° C. containing 1.5% by mass of boric acid and 5% by mass of potassium iodide, followed by a dryer at 60 ° C. The polarizing film was manufactured by drying for 240 seconds.

A sample film of 5 cm × 5 cm is sampled from the center of the obtained polarizing film so that it is in a crossed Nicol state on one polarizing plate (single transmittance 43.5%, polarization degree 99.9%). installed. Using a backlight with a brightness of 15,000 candela, observe the difference in brightness between the film collected from the center of the film roll and the film sampled from the end (transmission unevenness). Optical unevenness was evaluated.
A: The difference in light and dark due to the difference in transmittance between the film sampled from the center and the film sampled from both ends is not visible.
B: There is a slight difference in brightness between the film collected from the center and the film collected from both ends due to the difference in transmittance.
C: There is a clear contrast between the film collected from the center and the film collected from both ends.

Example 1
PVA film composed of PVA having a polymerization degree of 2,400 and a saponification degree of 99 mol% or more (thickness 30 μm, length 20,000 m, width 4.2 m, containing 10% by mass of glycerin as a plasticizer, and laurin as a surfactant A roll was produced by winding up 0.1% by mass of acid diethanolamide) around a cylindrical core. In addition, as a winding method, the contact roll (outside diameter: 210 mm, roll length: placed on the outer peripheral surface of the film roll formed from the already wound PVA film substantially parallel to the axial direction of the film roll. 4950 mm) was used, and a touch winding method for winding the PVA film was adopted. Specific conditions are shown in Table 1.

The average distance between adjacent films in the obtained roll was 4.15 μm. About the said roll, the external shape was evaluated by the said method. In addition, the polarizing film was produced and the optical unevenness was evaluated by the above method. The results are shown in Table 1.

Examples 2-8, Comparative Examples 2-5
The thickness of the PVA film used for the roll, the length, the width, the plasticizer content and the surfactant content, and the roll production conditions were changed in the same manner as in Example 1 except that the production conditions for the roll were changed as shown in Table 1. Fabrication and evaluation were performed. The results are shown in Table 1.

Comparative Example 1
PVA film composed of PVA having a polymerization degree of 2,400 and a saponification degree of 99 mol% or more (thickness 30 μm, length 20,000 m, width 3.3 m, containing 10% by mass of glycerin as a plasticizer, and laurin as a surfactant A roll was produced by winding up 0.1% by mass of acid diethanolamide) around a cylindrical core. Note that the near winding method was adopted as the winding method. Specific conditions are shown below.
[Contact Roll]
Shaft diameter: 210mm
Roll length: 4950mm
[Winding condition]
Winding contact pressure: None (near winding method)
Winding speed: 24 m / min Winding tension: 100 N / m
Parallelism: 0.8mm
Level: 0.2mm
The obtained roll was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Reference example 1
PVA film composed of PVA having a polymerization degree of 2,400 and a saponification degree of 99 mol% or more (thickness 60 μm, length 9,600 m, width 4.2 m, containing 10% by mass of glycerin as a plasticizer, and laurin as a surfactant A roll was produced by winding up 0.1% by mass of acid diethanolamide) around a cylindrical core. Note that the near winding method was adopted as the winding method. Specific conditions are shown below.
[Contact Roll]
Shaft diameter: 210mm
Roll length: 4950mm
[Winding condition]
Winding contact pressure: None (near winding method)
Winding speed: 12 m / min Winding tension: 52 N / m
Parallelism: 0.8mm
Level: 0.2mm
The obtained roll was evaluated in the same manner as in Example 1. The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Film roll 2 Contact roll 3 PVA film 4 Cylindrical core 5 Position where PVA film is wound 6 Film roll axis 7

Contact roll axis

8, 9 End of PVA film 10 Tangent line 11, 12 direction

Claims

A roll in which a polyvinyl alcohol film having a thickness of 45 μm or less and a length of 2,000 m or more is wound, and an average interval between adjacent films is 5 μm or less.
The roll according to claim 1, wherein an average interval between adjacent films is 2 μm or more.
The roll according to claim 1 or 2, wherein the content of the plasticizer in the polyvinyl alcohol film is 1 to 30% by mass.
The roll according to any one of claims 1 to 3, wherein the content of the surfactant in the polyvinyl alcohol film is 0.01 to 1.0 mass%.
The roll according to any one of claims 1 to 4, wherein the polyvinyl alcohol film has a width of 2 m or more.
The roll according to any one of claims 1 to 5, wherein the polyvinyl alcohol film is a raw film for producing an optical film.
The roll according to claim 6, wherein the optical film is a polarizing film.
A method for producing a roll in which a polyvinyl alcohol film having a thickness of 45 μm or less and a length of 2,000 m or more is wound up,
(A) In the winding process of the polyvinyl alcohol film, a contact roll disposed substantially parallel to the axial direction of the film roll is brought into contact with the outer peripheral surface of the film roll formed from the already wound polyvinyl alcohol film. While winding the polyvinyl alcohol film,
(B) The pressure between the film roll and the contact roll is 3 to 30 N per 1 m of the axial length of the film roll,
(C) The winding speed is 30 m / min or less,
Production method.
The manufacturing method according to claim 8, wherein the winding tension is 80 N or less per 1 m in the axial direction of the film roll.
The manufacturing method according to claim 8 or 9, wherein the parallelism A between the axis of the film roll and the axis of the contact roll, obtained from the distance between the axis of the film roll and the axis of the contact roll, is 0.7 mm or less.
The parallelism B of the film roll axis and the contact roll axis when the film roll and the contact roll are viewed from the horizontal direction is 0.2 mm, which is obtained from the level of the film roll axis and the contact roll axis. The production method according to any one of claims 8 to 10, which is as follows.
The production method according to any one of claims 8 to 11, wherein an average interval between adjacent films in a roll formed by winding a polyvinyl alcohol film is 5 袖 m or less.