TWI666238B - Polyvinyl alcohol film roll and method for manufacturing the same - Google Patents

Abstract

The present invention is a roll, which is a roll formed by rolling up a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more, and the average interval between adjacent films is 5 μm or less; and a method for manufacturing a roll, the thickness of which is A method for manufacturing a roll of a PVA film with a length of 45 μm or less and a length of 2,000 m or more adopts a contact roll-up method. The force applied between the film roll and the contact roll is 1 m in the axial direction of the film roll 3 ~ 30N, rolling speed is below 30m / min. Accordingly, it is possible to provide a PVA film roll, which is less prone to wrinkle or eccentricity and has a good appearance even when the PVA film is thin and has a long rolling length.

Description

Polyvinyl alcohol film roll and manufacturing method thereof

The invention relates to a polyvinyl alcohol film roll with a good appearance and a method for manufacturing the film 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 display, generally uses a polyvinyl alcohol film (hereinafter, "polyvinyl alcohol" will be abbreviated as "PVA"). ) After dyeing, uniaxial stretching, and further fixing treatment with a boron compound, etc. as necessary, after manufacturing a polarizing film, a protective film such as a cellulose triacetate (TAC) film is laminated on the surface of the obtained polarizing film to Manufacturing.

In recent years, LCDs are moving toward larger or thinner. The means for achieving thinness of the LCD is to consider thinning the glass used therefor. When the glass is made into a thin film, the polarizing plate is also made into a thin film, and it is necessary to reduce the shrinkage stress of the polarizing plate. Therefore, it is necessary to use a thinner PVA film to manufacture a thin polarizing film (refer to, for example, Patent Document 1).

The PVA film is generally stored or transported in a roll form in which a long PVA film is wound around a cylindrical core (see, for example, Patent Document 2). In order to efficiently and continuously manufacture even a large area, its optical properties A polarizing plate with excellent uniformity is still sought, and a PVA film roll having a wider width, a longer winding length, and excellent quality is sought. Patent Document 2 describes a method of winding a PVA film between a guide roller and a core tube attached to a cylindrical core tube, and winding the PVA film around the cylindrical core tube. The lead roller and the cylindrical core tube are placed in a non-contact state with a gap therebetween, or the roll is rolled up while the guide roller and the cylindrical core tube are in contact with each other through the PVA film. However, when the PVA film is thin and has a long winding length, a small amount of wrinkling or eccentricity of the center of gravity of the roll may occur, and a roll having a good appearance cannot be obtained. When such a PVA film roll is used as a raw material, variations and the like occur when the PVA film is rolled out, which impairs the uniformity of the PVA film and becomes a problem.

Prior art literature Patent literature

Patent Document 1 International Publication No. 2014/050697

Patent Document 2 Japanese Patent Laid-Open No. 2004-106376

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to provide a PVA film roll which is less likely to be wrinkled or eccentric and has a good appearance even when the PVA film is thin and has a long winding length.

The present inventors repeatedly studied to solve the above-mentioned problems, and found that the above-mentioned problems can be solved by setting the interval (thickness of the air layer) between the PVA films wound into a roll in a specific range. The opinions were further reviewed repeatedly, and the present invention was completed.

That is, the present invention relates to: [1] a roll, which is a roll formed by rolling up a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more, with an average interval between adjacent films of 5 μm or less; [2] such as The above [1] roll, wherein the width of the PVA film is 2 m or more; [3] As the above [1] or [2] roll, wherein the content of the plasticizer in the polyvinyl alcohol film is 1 to 30% by mass; [4] The volume of any one of the above [1] to [3], wherein the content of the surfactant in the polyvinyl alcohol film is 0.01 to 1.0% by mass; [5] As described in the above [1] to [4 [6] The roll of any one of the above, wherein the width of the polyvinyl alcohol film is 2 m or more; [6] The roll of any one of the above [1] to [5], wherein the PVA film is a raw film for optical film manufacturing; 7] The roll as described in [6] above, wherein the optical film is a polarizing film; [8] A method for manufacturing a roll, which is a method for manufacturing a roll made by rolling up a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more (A) During the rolling process of the PVA film, the outer circumferential surface of the film roll formed by the rolled PVA film is brought into contact with a contact roller arranged substantially parallel to the axis direction of the film roll, and Force from the PVA film, (b) is applied between the film roll and the contact roller in the axial direction for the length of film per 1m of 3 ~ 30N, (c) Rolling speed is 30m / min or less; [9] The method for manufacturing a roll as described in [8] above, wherein the roll tension is 80N or less per 1m in the axial direction of the film roll; [10] as described above [ 8] or [9] The method for producing a roll, 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; 11] The method for manufacturing a roll as described in any one of [8] to [10] above, wherein the film roll and contact are viewed from a horizontal direction obtained from the horizontality of the axis of the film roll and the horizontality of the axis of the touch roll. The parallelism B between the axis of the film roll at the time of the roll and the axis of the contact roll is 0.2 mm or less; [12] The method for manufacturing a roll according to any one of [8] to [11] above, wherein the PVA film is rolled up In the roll, the average interval between adjacent films is 5 μm or less.

According to the present invention, it is possible to provide a PVA film roll having a good external appearance even when the PVA film is thin and the winding length is long. According to the manufacturing method of the present invention, such a roll can be efficiently manufactured.

1‧‧‧ film roll

2‧‧‧ contact roller

3‧‧‧PVA film

4‧‧‧ cylindrical core

5‧‧‧PVA film roll up position

6‧‧‧ film roll shaft

7‧‧‧ contact roller shaft

8、9‧‧‧PVA film end

10‧‧‧ Tangent

11, 12‧‧‧ direction

FIG. 1 is a schematic diagram showing an example of a contact roll-up type.

Fig. 2 is a schematic diagram showing an example of a close-up type.

Fig. 3 is an example of a schematic view of the film roll 1 and the contact roll 2 as viewed from the direction 11 of the tangent line 10 of the touch roll 2 at the position where the touch roll 2 is in contact with the film roll 1 in the first diagram.

FIG. 4 is an example of a schematic view of the film roll 1 and the touch roll 2 viewed from the horizontal direction 12 in the first figure.

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

In order to obtain the roll of the present invention by rolling up the PVA film, it is preferable that the PVA film is wound around a cylindrical core from the viewpoint of the quality and usability of the obtained roll. The type of the cylindrical core is not particularly limited, and examples thereof include metal products, plastic products, paper products, and wooden products. In addition, products using both metal and plastic, products using both metal and paper, and products using both plastic and paper can also be used, and the core of the composite body can also be used. Among these, metal and / or plastic are used from the viewpoints that the strength of the present invention is more significant and the effect of the present invention is more prominently exhibited, and there are few dusts that are likely to cause problems when producing optical films such as polarizing films. The core made of metal is preferred. From the viewpoint that it is not easily affected by abrasion and the like even after repeated use, a core made of metal is preferable. Relative to the total mass of the cylindrical core, the proportion of the mass of metal and plastic is preferably 50% by mass or more, 80% by mass or more is preferred, 95% by mass or more is preferred, and 100% by mass is particularly preferred. .

Examples of the metal include iron, stainless steel, and aluminum. One of these metals may be used alone or two or more of them may be used in combination. From the viewpoints of strength, lightness, and price, among these, aluminum and iron are preferred.

Examples of the plastic include polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate, polyamide, epoxy resin, and polymer. Ethyl urethane, polyurea, silicone resin, etc. can be used alone or in combination of two or more. Of these, polyvinyl chloride is preferred. From the viewpoint of strength and the like, the plastic is also preferably a fiber-reinforced plastic (FRP) such as carbon fiber-reinforced plastic.

The length of the cylindrical core is not particularly limited. From the viewpoint of usability and the like, it is preferably within a range of 5 to 100 cm, and more preferably within a range of 10 to 45 cm. 15 A range of ~ 30cm is more preferred.

The diameter of the cylindrical core is not particularly limited. From the viewpoints of strength and usability, the outer diameter is preferably in the range of 50 to 800 mm, more preferably in the range of 80 to 500 mm, and 100 to 300 mm. The range is more preferred, and the range from 150 to 250 mm is particularly preferred. In addition, from the viewpoints of strength, usability, etc., the thickness of the cylindrical core is preferably in a range of 2 to 50 mm, more preferably in a range of 3 to 20 mm, and even more preferably in a range of 4 to 10 mm.

Examples of the PVA constituting the PVA film used in the present invention include, for example, an unmodified PVA obtained by saponifying a polyvinyl ester obtained by polymerizing a vinyl ester, and a graft copolymerizing monomer with PVA. Chain-modified PVA; modified PVA obtained by saponifying a modified polyvinyl ester copolymerized with a vinyl ester and a comonomer; aldehydes such as formalin, butyraldehyde, benzaldehyde, etc. Unmodified PVA or a part of the hydroxyl groups of the modified PVA are crosslinked, so-called polyvinyl acetal resin and the like. When the PVA constituting the PVA film is a modified PVA, the modification amount of 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 caseinate, vinyl valerate, vinyl trimethyl acetate, vinyl laurate, and stearic acid. Vinyl ester, vinyl benzoate, vinyl acetic acid, etc. These vinyl esters can be used alone or in combination. From the viewpoint of productivity, vinyl acetate is preferred among these vinyl esters.

Examples of the comonomer include olefins (α-olefins, etc.) having a carbon number of 2 to 30, such as ethylene, propylene, 1-butene, and isobutylene; acrylic acid or a salt thereof; methyl acrylate, ethyl acrylate, Acrylic acid such as n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, third butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, etc. Esters (such as 1 to 18 alkyl esters of acrylic acid); methacrylic acid or its salts; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, N-butyl methacrylate, isobutyl methacrylate, third butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, stearyl methacrylate, etc. Methacrylic acid esters (such as 1 to 18 alkyl esters of methacrylic acid); acrylamide; N-methacrylamide, N-ethylacrylamide, N, N-dimethyl Acrylamide, diacetone acrylamide, acrylamide propanesulfonic acid or a salt thereof, acrylamide propyldimethylamine or Salt, acrylamide derivatives such as N-methylmethacrylamide or derivatives thereof; methacrylamide; N-methylmethacrylamide, N-ethylmethacrylamide, methyl Methacrylamide derivatives such as acrylamine propanesulfonic acid or a salt thereof, methacrylamide propyldimethylamine or a salt thereof, N-methylolmethacrylamide or a derivative thereof; N- Vinyl formamidine N-vinylamines such as amines, N-vinylacetamide, N-vinylpyrrolidone; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether Vinyl ethers such as n-butyl vinyl ether, isobutyl vinyl ether, third butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, etc .; acrylonitrile, methyl Nitriles such as acrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride; allyl compounds such as allyl acetate, allyl chloride; maleic acid, Ikon Derivatives such as acids, unsaturated dicarboxylic acids, salts or esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate; unsaturated sulfonic acids or derivatives thereof. These comonomers may be used individually by 1 type, and may use 2 or more types together. Of these comonomers, α-olefins are preferred, and ethylene is particularly preferred.

From the viewpoint of the polarization performance and durability of the obtained polarizing film, 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. In addition, from the viewpoints of ease of production and extensibility of forming a homogeneous PVA film, the degree of polymerization of PVA is preferably 8,000 or less, and more preferably 6,000 or less. The degree of polymerization of PVA in this specification refers to the average degree of polymerization measured in accordance with the description of JIS K6726-1994. After re-saponifying and purifying PVA, it is determined from the limiting viscosity measured in water at 30 ° C.

From the viewpoint of the polarization performance and durability of the obtained polarized light film, the saponification degree of PVA is preferably 95 mol% or more, more preferably 98 mol% or more, and more preferably 99 mol% or more . The degree of saponification of PVA in this specification refers to the structural unit (typical example is a vinyl ester unit) and a vinyl alcohol unit that can be converted into a vinyl alcohol unit by saponification. The total mole number of the element is the ratio (mole%) of the mole number of the vinyl alcohol unit. The degree of saponification of PVA can be measured in accordance with the description of JIS K6726-1994.

The PVA constituting the PVA film may be one type of PVA or two or more types of polymerization degree, saponification degree, modification degree, and the like, or PVA different from two or more kinds. The content of PVA 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 even more preferably in the range of 85 to 100% by mass.

From the viewpoints of improving mechanical properties such as punching strength, improving program passability or elongation at the time of secondary processing, and obtaining a roll of the present invention more efficiently, the PVA film preferably contains a plasticizer. Suitable plasticizers include polyols such as ethylene glycol, glycerol, diglycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, and the like. The PVA film may contain one or two or more of these plasticizers. Among these plasticizers, one or two or more of glycerin, diglycerin, and ethylene glycol are suitable, and glycerin is more suitable from the viewpoints of extending the PVA film and improving the extensibility during use.

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, the flexibility of the film is insufficient. Therefore, problems such as film breakage or poor extensibility during the production of a polarizing plate are liable to occur when rolled up. From such a viewpoint, the content is preferably 5 mass% or more, and more preferably 10 mass% or more. In addition, when the content of the plasticizer in the PVA film exceeds 30% by mass, it tends to occur in roll storage. When it oozes out, the physical properties of the PVA film are not uniform, and the uniformity is damaged or the film is stuck. From such a viewpoint, the content is preferably 20% by mass or less, and more preferably 15% by mass or less.

The PVA film preferably contains a surfactant from the viewpoints of its usability and improvement of peelability from a film-forming apparatus during the production of a PVA film. The type of the surfactant is not particularly limited, and examples thereof include an anionic surfactant and a nonionic surfactant.

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

Nonionic surfactants include, for example, alkyl ether types such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; alkylphenyl ether types such as polyoxyethylene octyl phenyl ether; polyoxyethylene laurate Alkyl ester type; alkyl amine type such as polyoxyethylene lauryl amino ether; alkyl amine type such as polyoxyethylene lauryl amine; polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; Alkanolamines such as diethanolammonium laurate and diethanolamine oleate; allylphenyl ethers such as polyoxyalkylene allylphenyl ether; and the like.

The PVA film may contain one or more of these surfactants. From the viewpoint of excellent effect of reducing film surface abnormality during film formation, among these surfactants, nonionic surfactants are preferred, and alkanolamine type surfactants are preferred. Fats A dialkanolamine (for example, diethanolamine and the like) of a group carboxylic acid (for example, a saturated or unsaturated aliphatic carboxylic acid having 8 to 30 carbons) is more preferred.

In the present invention, the content of the surfactant in the PVA film is preferably in the range of 0.01 to 1% by mass. If the surfactant If the content is too small, there is a concern that the usability of the PVA film or the peelability of the film-forming apparatus during the production of the PVA film may be further deteriorated or blocking may occur. From this viewpoint, the content of the surfactant is preferably 0.02% by mass or more, and more preferably 0.05% by mass or more. On the other hand, if the content of the surfactant is too high, the uniformity of the film will be impaired due to bleeding, and thus the resulting polarizing plate may cause problems such as flare or deterioration of the transparency of the film. From this viewpoint, the content of the surfactant is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less.

The PVA film may further contain other components such as an antioxidant, an ultraviolet absorber, a slip agent, a colorant, a preservative, an antifungal agent, a polymer compound other than the above-mentioned components, and moisture, if necessary. The PVA film may contain one or two or more of these other components.

The production method of the PVA film is not particularly limited, and it is suitable to adopt a production method in which the thickness and width of the film after the film formation are relatively uniform. For example, the above-mentioned PVA constituting the PVA film may be used, and a plasticizer, a surfactant and One or two or more of the other components mentioned above are dissolved in a liquid medium, or a film-forming dope containing PVA and, if necessary, a plasticizer, a surfactant, the other components described above, and a liquid medium. One or two or more types of film-forming dope made by melting PVA. When the film-forming dope contains at least one of a plasticizer, a surfactant, and the other components described above, these components are preferably uniformly mixed.

Examples of the liquid medium used in the preparation of the film-forming dope include water, dimethylformamide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine, diethylenetriamine, etc. One or more of them. Among these, water and dimethylarsin are preferred, and water is more preferred.

The volatile component ratio of the film-forming stock solution (the content of volatile components in the film-forming stock solution that can be removed by volatilization or evaporation during film-forming) will depend on the degree of polymerization of PVA, the film-forming method, and film-forming conditions It varies from 20% by mass, 25% by mass or higher is preferred, 30% by mass or higher is preferred, 40% by mass or higher is particularly preferred, and 95% by mass or lower is preferred, 90% by mass % Or less is preferred, 85% by mass or less is more preferred, and 70% by mass or less is particularly preferred. By setting the volatile component ratio of the film-forming dope above the above-mentioned lower limit, the viscosity of the film-forming dope will not be too high. When the film-forming dope is prepared, filtering or defoaming proceeds smoothly, and it is easy to produce a PVA film with few foreign matter or defects. On the other hand, by setting the volatile component ratio of the film-forming dope below the above-mentioned upper limit, the concentration of the film-forming dope is not excessively low, and it is easy to manufacture a PVA film on an industrial scale.

Examples of the film forming method when a PVA film is produced using the above film forming stock solution include a casting film forming method, an extrusion film forming method, a wet film forming method, and a colloidal film method. These film forming methods may be used alone or in combination of two or more. From the viewpoint of obtaining a good PVA film, among these film forming methods, a casting film forming method and an extrusion film forming method are preferred.

An example of a specific manufacturing method of a PVA film is, for example, a known film-like discharge device (film-like pouring device) using a T-slot mold, hopper plate, I-die, lip coating mold, etc., which is industrially suitable, Membrane stock solution is evenly discharged or poured to the rotation located on the most upstream side and added The voluminous component is evaporated and dried on one side of the heated film on the circumferential surface of the first roll (or conveyor belt), which is discharged or cast onto the circumferential surface of the first roll (or conveyor belt). A method of further drying on the circumferential surface of one or more rotating and heated rolls on the downstream side, or by a hot air drying device. Drying using a heated coil and drying using a hot-air drying device may be appropriately combined and implemented.

The thickness of the PVA film of the roll of the present invention must be 45 μm or less. By setting the thickness of the PVA film to 45 μm or less, a thin polarizing film can be efficiently produced. Moreover, by using such a thin polarizing film, a thin polarizing plate can be efficiently manufactured. Conventionally, when a PVA film is thin and has a long winding length, a small amount of wrinkles or eccentricity occur, and there is a problem that a roll having a good appearance 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, wrinkles or eccentricity are unlikely to occur, and a PVA film roll having a good appearance shape can be obtained. Therefore, when the thickness of the PVA film is 45 μm or less, the effect of the present invention can be significantly exhibited. From the viewpoints as described above, the thickness of the PVA film is preferably 40 μm or less, more preferably 35 μm or less, more preferably 30 μm or less, particularly preferably 25 μm or less, and most preferably 20 μm or less. On the other hand, if the thickness of the PVA film is too small, the secondary processing of the film processed into an optical film such as a polarizing film tends to be difficult to perform. Therefore, the thickness is preferably 1 μm or more, more preferably 3 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more.

The winding length of the rolled PVA film of the present invention, that is, the length of the rolled PVA film, must be 2,000 m or more. By setting the length of the PVA film to 2,000m or more, Optical films, such as light films, have large areas, and products with excellent uniformity of optical performance can be continuously and efficiently produced. In addition, conventionally, when a PVA film is thin and has a long winding length, a small amount of wrinkling or eccentricity occurs, and there is a problem that 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, wrinkles or eccentricity are unlikely to occur, and a PVA film roll having a good appearance shape can be obtained. Therefore, when the length of the PVA film is 2,000 m or more, the effect of the present invention can be significantly exhibited. From the viewpoints as described above, the length of the PVA film is preferably 3,000 m or more, more preferably 4,000 m or more, more preferably 5,000 m or more, particularly preferably 8,000 m or more, and most preferably 12,000 m or more. The upper limit of the length of the PVA film is not particularly limited. From the viewpoint of easily obtaining a PVA film roll having a good appearance, the length is preferably 30,000 m or less, and more preferably 22,000 m or less. The length of PVA film is 18,000m or less, and even 15,000m or less.

The width of the PVA film is not particularly limited, and can be set to, for example, 50 cm or more. Incidentally, generally, the wider the width of the PVA film, the more likely the resulting roll will become wrinkled or eccentric. In contrast, according to the present invention, the occurrence of wrinkles or eccentricity can be reduced even when the width of the PVA film is wide. Therefore, in this case, the effect of the present invention can be more significantly exerted. In addition, by using a wide PVA film, a wide polarizing film that can be applied to the enlargement of the LCD screen can be manufactured. From such a viewpoint, the width of the PVA film is preferably 2 m or more, more preferably 2.5 m or more, more preferably 2.7 m or more, particularly preferably 3 m or more, and 3.5 m or more. The upper limit of the width of the PVA film is not particularly limited. From the viewpoint of easily obtaining a PVA film roll having a good appearance and shape, etc. It appears that the width is preferably less than 6m, more preferably less than 5m, and more preferably less than 4.2m. From the viewpoint of obtaining a PVA film having a particularly excellent appearance shape, it is preferably 4 m or less, and more preferably 3.8 m or less.

For the roll of the present invention, the average interval between adjacent films (between adjacent PVA films in the diameter direction of the roll) must be 5 μm or less. This average interval corresponds to the thickness of the air layer between the films. By setting the average interval to be 5 μm or less, even when the PVA film is thin and the winding length is long, wrinkles or eccentricity are unlikely to occur, and a roll having a good external appearance can be obtained. From such a viewpoint, the average interval is preferably 4.9 μm or less, more preferably 4.5 μm or less, more preferably 4.2 μm or less, 4 μm or less, or even 3.8 μm or less. In addition, if the average interval between adjacent films is less than 2 μm, blocking may easily occur, changes may occur when the PVA film is rolled out, or the appearance of the film may be wrinkled due to the tight winding of the PVA film roll, etc. And the problem of impairing uniformity. From such a viewpoint, the average interval is preferably 2 μm or more, more preferably 2.5 μm or more, more preferably 3 μm or more, and particularly preferably 3.5 μm or more.

The average interval between the adjacent thin films can be obtained by the following method. That is, the average interval N between the adjacent films of the outer diameter H (m) roll formed by rolling a PVA film having a length L (m) and a thickness M (μm) of the cylindrical core of the outer diameter D (m) (μm) can be calculated by the following formula: N = {(π / 4) (H ² -D ² ) / L} × 10 ⁶ -M

The method for producing the roll of the present invention is not particularly limited. It is preferable that the aforementioned roll can be efficiently produced according to the following production method of the present invention. That is, the manufacturing method of the present invention is a manufacturing method of a roll in which a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more is rolled up, and (a) During the rolling process of the PVA film, the outer circumferential surface of the film roll (film-like portion) formed by the rolled PVA film and a contact roller arranged approximately parallel to the axis direction of the film roll The PVA film is contacted and rolled up at the same time, (b) the force applied between the film roll and the contact roll is 3 to 30 N per 1 m of the length of the film roll in the axial direction, and (c) the rolling speed is 30 m / min or less.

In the manufacturing method of the present invention, the PVA film used for manufacturing the roll may be the PVA film used for manufacturing the roll of the present invention.

The manufacturing method of the present invention adopts a contact roll-up method, in which the outer circumferential surface of a film roll formed of the rolled PVA film and the film roll arranged in the process of rolling the PVA film are arranged approximately parallel to the film roll. The contact rollers in the axial direction are in contact with each other, and the PVA film is rolled up at the same time. FIG. 1 is a schematic diagram showing an example of the contact roll-up type. As shown in FIG. 1, the state in which the contact rolls 2 arranged substantially parallel to the axial direction of the film roll 1 directly contacts the outer circumferential surface of the film roll 1 formed of the rolled PVA film 3. Then, the PVA film 3 is further rolled up to produce a roll. As the touch roll 2 to be used, a roll longer than the axial length of the film roll 1 can be used. When the PVA film 3 is rolled up at the position 5 of the film roll 1, the film roll 1 and the contact roll 2 should be in full contact with each other in the axial direction of the film roll 1. In addition, as another method different from the contact roll-up type, an approximate roll-up type is known as a schematic view shown in FIG. 2. As shown in FIG. 2, when the PVA film 3 is rolled up in a close-up type, a space is maintained between the outer circumferential surface of the film roll 1 formed of the rolled PVA film and the contact roll 2 ( gap).

The length of the contact roller 2 is not particularly limited, and 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 even more preferably within a range of 10 to 50 cm.

The diameter of the contact roller 2 is not particularly limited. From the viewpoints of strength, usability, etc., its outer diameter is preferably within a range of 50 to 1000 mm, and preferably within a range of 75 to 800 mm. The range is more preferable, and the range of 125 to 350 mm is particularly preferable. The material of the surface layer of the touch roller 2 is not particularly limited, and examples thereof include rubber, resin, and metal, and rubber is particularly suitable.

In the manufacturing method of the present invention, when the PVA film 3 is rolled up, the force applied between the film roll 1 and the contact roll 2 (the force pressing the contact roll 2 against the film roll 1) is set in the axial direction of the film roll 1. The upper length is in the range of 3 ~ 30N per 1m. Hereinafter, this force may be referred to as "roll-up contact pressure", and "N / m" may be used as a unit for representing a force per 1 m in length in the axial direction of the film roll. By setting the rolling contact pressure within the above range, the roll of the present invention can be efficiently manufactured. From this point of view, the rolled contact pressure is preferably 20 N / m or less, more preferably 10 N / m or less, and even more preferably 8 N / m or less. From the viewpoint that the roll of the present invention can be produced more efficiently, it is preferably 3.5 N / m or more, and more preferably 4 N / m or more.

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

In the manufacturing method of the present invention, the rolling tension when the PVA film 3 is rolled (the tension in the longitudinal direction of the PVA film 3 when the PVA film is rolled) is set to a film roll formed from the rolled PVA film The length in the axial direction of 1 is preferably 80 N or less per 1 m. Hereinafter, "N / m" may be used as a unit for indicating the roll tension per 1 m of the length of the film roll 1 in the axial direction. By setting the take-up tension within the above range, the roll of the present invention can be manufactured more efficiently. From this point of view, the winding tension is preferably 75 N / m or less, and more preferably 70 N / m or less. From the viewpoint that the roll of the present invention can be produced more efficiently, the aforementioned winding tension is preferably 20 N / m or more, 40 N / m or more is preferable, 45 N / m or more is more preferable, and 50 N / m or more is particularly preferable. good.

Fig. 3 is an example of a schematic view of the film roll 1 and the contact roll 2 as viewed from the direction 11 of the tangent line 10 of the touch roll 2 at the position where the touch roll 2 is in contact with the film roll 1 in the first diagram. In the manufacturing method of the present invention, the parallelism A between the axis of the film roll 1 and the axis of the touch roll 2 obtained from the distance between the axis of the film roll 1 and the axis of the touch roll 2 is preferably 0.7 mm or less. In this way, when the PVA film 3 is rolled up at the position 5 of the film roll 1, the film roll 1 and the contact roll 2 easily come into full contact with each other in the axial direction of the film roll 1. Therefore, the present invention with a good appearance can be manufactured more effectively Volume. The parallelism A is preferably 0.5 mm or less, and more preferably 0.2 mm or less. In the present invention, the parallelism A represents the distance b from one end b of the shaft 7 of the touch roll 2 to the axis 6 of the film roll 1 and the distance b from the other end b ′ of the shaft 7 of the touch roll 2 to the axis 6 of the film roll 1 '-a' difference. One end b of the shaft 7 of the touch roller 2 is a position closest to the end 8 of the PVA film 3, and the other end b ′ is a position closest to the end 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 touch roll 2 viewed from the horizontal direction 12 in the first figure. In the manufacturing method of the present invention, the axis and contact of the film roll 1 when the film roll 1 and the contact roll 2 are viewed from a horizontal direction, which are obtained from the horizontality of the axis of the film roll 1 and the level of the shaft of the contact roll 2 The parallelism B of the axis of the roller 2 is preferably 0.2 mm or less. In this way, when the PVA film 3 is rolled up at the position 5 of the film roll 1, the film roll 1 and the contact roll 2 easily come into full contact with each other in the axial direction of the film roll 1. Therefore, the present invention with a good appearance can be manufactured more effectively Volume. The parallelism B is preferably 0.15 mm or less, and more preferably 0.1 mm or less. The parallelism B in the present invention will be specifically described as follows. The axis 7 of the touch roller 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 surface, the distance dc from one end d of the shaft 7 of the contact roller 2 to the axis 6 of the film roll 1 and the distance d 'from the other end d ′ of the shaft 7 of the contact roller 2 to the axis 6 of the film roll 1 The difference of -c 'is set to the parallelism B. One end d of the shaft 7 of the contact roller 2 is a position closest to the end 8 of the PVA film 3, and the other end d ′ is a position closest to the end 9 of the PVA film 3. The parallelism B can be obtained by measuring the horizontality in the axial direction of the film roll 1 and the touch roll 2 using a leveling instrument.

In the roll obtained in this manner, the average interval between adjacent films is preferably 5 μm or less. By setting the average interval to be 5 μm or less, even when the PVA film is thin and the winding length is long, wrinkles or eccentricity are unlikely to occur, 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, and 4.2 μm or less. More preferably, it is 4 μm or less, or even 3.8 μm or less. On the other hand, the average interval is preferably 2 μm or more, more preferably 2.5 μm or more, more preferably 3 μm or more, and particularly preferably 3.5 μm or more.

The use of the PVA film of the roll of the present invention is not particularly limited, and it can be used, for example, in a pharmaceutical packaging film, a hydraulic transfer substrate film, an embroidery substrate film, an artificial marble molding release film, a seed packaging film, It is used for various water-soluble films, such as a film for dirt storage bags. According to the present invention, even if the PVA film is thin and has a long winding length, it is possible to provide a roll that is less likely to be wrinkled or eccentric, and has a good appearance. Even if such a roll is used, an optical film having a large area and excellent uniformity in optical performance can be efficiently and continuously produced. Therefore, the PVA film is preferably used as a raw material film for producing an optical film. Examples of such an optical film include a polarizing film and a phase difference film, and a polarizing film is preferred. Such an optical film can also be manufactured by performing processing, such as uniaxial stretching, using the said PVA film.

The method for producing a polarizing film using a PVA film is not particularly limited, and any of the conventionally known methods can be adopted. This method includes, for example, a method of performing dyeing and uniaxial stretching using a PVA film rolled up from the roll of the present invention, or uniaxial stretching of a dye-containing PVA film rolled out from the roll of the present invention. A more specific method for manufacturing a polarizing film includes a method of swelling, dyeing, uniaxially stretching the PVA film rolled up from the roll of the present invention, and further performing a cross-linking treatment, a fixing treatment, a drying, a heat treatment, etc. as necessary. method. In this case, the order of each treatment such as swelling, dyeing, cross-linking treatment, uniaxial stretching, and fixing treatment is not particularly limited, and one or the same may be performed. When more than two kinds of processing are performed. In addition, one or two or more of each treatment may be performed two or more times.

The manufactured polarizing film is usually bonded with an optically transparent and mechanically strong protective film on one or both sides, and is used in the form of a polarizing plate. As the protective film, a cellulose triacetate (TAC) film, a cyclic olefin polymer (COP) film, an acetic acid, cellulose butyrate (CAB) film, an acrylic film, a polyester film, and the like can be used. Examples of the adhesive used for bonding include PVA-based adhesives and urethane-based adhesives. PVA-based adhesives are particularly suitable.

The polarizing plate obtained as described above can be used as a component of an LCD after being coated with an acrylic-based adhesive or the like, and then bonded to a glass substrate. It can also be laminated with phase difference film, viewing angle enhancement film, and brightness enhancement film at the same time.

[Example]

Hereinafter, the present invention will be further described in detail through examples, but the present invention is not limited at all by these examples.

[Evaluation of appearance]

The appearance of the roll was evaluated in accordance with the following criteria.

A: No wrinkles or eccentricities, good appearance

B: Although a small amount of wrinkles was observed, no eccentricity occurred and the appearance was good

C: A small amount of wrinkles or eccentricity occurred, and the appearance was poor

[Evaluation of light spots]

Sample films of 15 cm × 15 cm were taken from the central portion and both end portions of the film rolls obtained in the following examples and comparative examples. With the PVA The film is subjected to a swelling step, a dyeing step, a crosslinking step, an extension step, a fixing treatment step, and a drying step to produce a polarizing film. Four specimen films were mounted on an extension jig. It was immersed in water at a temperature of 30 ° C for 1 minute. During this period, the uniaxial extension in the longitudinal direction (MD) (the first stage extension) was 2.2 times the original length. Then, immerse in a dyeing bath at a temperature of 30 ° C. containing iodine at a concentration of 0.03% by mass and potassium iodide at a concentration of 3.0% by mass for 2 minutes, and during this period, uniaxially extend in the longitudinal direction (MD) (extended in the second stage) ) To 3.2 times its original length. Next, it was immersed in a crosslinking bath at a temperature of 30 ° C. containing boric acid at a concentration of 3.0% by mass and potassium iodide at a concentration of 3.0% for 2 minutes, during which period it was uniaxially extended in the longitudinal direction (MD) (paragraph 3 Extended) to 3.6 times its original length. It was further immersed in a stretching bath at a temperature of 55 ° C. containing boric acid at a concentration of 4.0% by mass and potassium iodide at a concentration of 5.0% by mass. During this period, uniaxial stretching was performed (stretching in the fourth step) among four films. At the time when the two pieces were broken, the other two pieces that were not broken were taken out from the extension bath. Then, the film was washed by immersing in a fixed-treatment bath at a temperature of 22 ° C. containing boric acid at a concentration of 1.5% by mass and potassium iodide at a concentration of 5% by mass for 5 seconds. The dryer dries for 240 seconds to produce a polarizing film.

A 5 cm × 5 cm sample film was taken from the central portion of the obtained polarizing film, and was placed on a single polarizing plate (a single light transmittance of 43.5%, a polarization degree) so as to be in a crossed nicol state. 99.9%). Using a backlight with a brightness of 15,000 candles, observe the difference in light and dark caused by uneven light transmittance (light spots) between the film taken from the center of the film roll and the film taken from the end, and evaluate the light spot according to the following criteria.

A: Between the film taken from the central portion and the film taken from both end portions, the difference in light and dark due to the difference in light transmittance was not observed, and it was uniform.

B: Between the film taken from the central portion and the film taken from both end portions, the difference in light transmittance causes a slight difference in brightness and darkness.

C: There is a significant difference in brightness between the film taken from the central portion and the film taken from both end portions.

Example 1

A PVA film (thickness 30 μm, length 20,000 m, width 4.2 m) made of PVA having a polymerization degree of 2,400 and a saponification degree of 99 mol% or more (containing 10% by mass of glycerin as a plasticizer and lauric acid as a surfactant) Diethanolamine (0.1% by mass) was rolled up on a cylindrical core to produce a roll. In addition, the rolling method is a contact rolling method in which an outer circumferential surface of a film roll formed of a rolled PVA film and a contact roller (outer diameter: 210 mm, Roll length: 4950mm) while rolling up the PVA film. The specific conditions are shown in Table 1.

The average interval between adjacent films of the obtained roll was 4.15 μm. The appearance of the roll was evaluated by the method described above. In addition, the above method was used to produce a polarizing film and evaluate light spots. The above results are shown in Table 1.

Examples 2 to 8, Comparative Examples 2 to 5

The thickness, length, width, plasticizer content, and surfactant content of the PVA film used for the roll and the manufacturing conditions of the roll were changed as shown in Table 1, and the roll was performed in the same manner as in Example 1. Production and evaluation. The results are shown in Table 1.

Comparative Example 1

A PVA film (thickness: 30 μm, length: 20,000 m, width: 3.3 m, 10% by mass of glycerin as a plasticizer), and lauric acid as a surfactant were formed of PVA film having a polymerization degree of 2,400 and a saponification degree of 99 mole% or more Diethanolamine (0.1% by mass) was rolled up on a cylindrical core to produce a roll. In addition, the roll-up method is a close roll-up method. Specific conditions are disclosed below.

[Contact roller]

Shaft diameter: 210mm

Roll length: 4950mm

[Roll up condition]

Roll-up contact pressure: None (close to roll-up)

Rolling speed: 24m / min

Rolling tension: 100N / m

Parallelism A: 0.8mm

Parallelism B: 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

A PVA film (thickness of 60 μm, length of 9,600 m, width of 4.2 m, containing 10% by mass of glycerin as a plasticizer, and lauric acid di as a surfactant are formed of a PVA film composed of PVA having a polymerization degree of 2,400 and a saponification degree of 99 mol% or more Ethanolamine 0.1% by mass) was rolled up on a cylindrical core to produce a roll. In addition, the roll-up method uses a close roll-up method. Specific conditions are disclosed below.

[Contact roller]

Shaft diameter: 210mm

Roll length: 4950mm

[Roll up condition]

Roll-up contact pressure: None (close to roll-up)

Rolling speed: 12m / min

Rolling tension: 52N / m

Parallelism A: 0.8mm

Parallelism B: 0.2mm

The obtained roll was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Claims (9)

A roll is a roll made of a polyvinyl alcohol film having a thickness of 45 μm or less and a length of 2,000 m or more. The average interval between adjacent films is 5 μm or less. The polyvinyl alcohol film is a raw film for manufacturing polarizing films. . As in the volume of claim 1, the average interval between adjacent films is 2 μm or more. For example, if the item 1 or 2 is requested, the content of the plasticizer in the polyvinyl alcohol film is 1 to 30% by mass. For example, the volume of the request item 1 or 2, wherein the content of the surfactant in the polyvinyl alcohol film is 0.01 to 1.0% by mass. For example, if the item 1 or 2 is requested, the width of the polyvinyl alcohol film is 2m or more. A method for producing a roll according to any one of claims 1 to 5, which is a method for producing a roll made by rolling up a polyvinyl alcohol film having a thickness of 45 μm or less and a length of 2,000 m or more, (a) in polyethylene During the rolling of the alcohol film, the outer circumferential surface of the film roll formed of the rolled polyvinyl alcohol film is brought into contact with a contact roller arranged approximately parallel to the axial direction of the film roll, and the polyvinyl alcohol is rolled up at the same time. The film, (b) the force applied between the film roll and the contact roll is 3 to 30 N per 1 m of the length of the film roll in the axial direction, and (c) the winding speed is 30 m / min or less. For example, the method for manufacturing a roll of claim 6, wherein the roll tension is 80 N or less per 1 m of the length in the axial direction of the film roll. The method for manufacturing a roll of claim 6 or 7, wherein the parallelism A between the axis of the film roll and the axis of the contact roll, which is 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 method of manufacturing a roll of claim 6 or 7, wherein the axis and contact of the film roll when the film roll and the contact roll are viewed from a horizontal direction, as determined from the horizontality of the axis of the film roll and the level of the shaft of the contact roll The parallelism B of the shaft of the roller is 0.2 mm or less.