KR20180039151A - Polyvinyl alcohol film roll - Google Patents

Abstract

A roll having a thickness of 45 탆 or less and a PVA film having a length of 2,000 m or more wound therebetween, the roll having an average gap of 5 탆 or less between neighboring films; And a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more is wound therebetween, wherein a touch winding method is adopted and the pressure between the film roll and the contact roll is 1 m 3 to 30 N per roll, and a winding speed of 30 m / min or less. As a result, even if the PVA film is thin and the winding length is long, wrinkles and eccentricity are not generated well, and a roll of the PVA film having a good appearance is provided.

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.

Polarizing plates, which are basic components of a liquid crystal display (LCD) such as a liquid crystal television or a liquid crystal monitor, are generally colored with a polyvinyl alcohol film (hereinafter, "polyvinyl alcohol" may be abbreviated as "PVA" Axis stretching and, if necessary, further fixing treatment with a boron compound or the like to produce a polarizing film, and then a protective film such as a cellulose triacetate (TAC) film is stuck to the surface of the obtained polarizing film .

In recent years, an increase in size and thinness of LCDs is progressing. As means for achieving thinning of the LCD, a method of thinning the glass used therefor can be considered. When the glass is made thin, it is necessary to reduce the shrinkage stress of the polarizing plate by thinning the polarizing plate. Therefore, it is required to produce a thin polarizing film using a thinner PVA film (see, for example, Patent Document 1, etc.).

The PVA film is conventionally stored or transported in the form of a roll in which a long PVA film is wound on a cylindrical core (see, for example, Patent Document 2). There is a demand for a roll of a PVA film that is wider, has a longer winding length, and is more excellent in quality, even in a polarizing plate having a large area, in order to continuously produce excellent optical performance uniformity with good efficiency. Patent Document 2 discloses a method for winding a PVA film between a guide roll formed in a cylindrical core tube and a core tube and winding the PVA film on the cylindrical core tube, wherein the guide roll and the cylindrical core tube are spaced Or in a state in which the guide roll and the cylindrical core tube are in contact with each other via the PVA film. However, when the PVA film is thinner and the winding length is long, fine wrinkles or eccentricity in which the center of gravity of the roll is displaced is generated, and a roll having a good outer appearance is not obtained. When such a roll of the PVA film is used as a raw material, fluctuation occurs in the roll of the PVA film and the uniformity of the PVA film is impaired, which is a problem.

International Publication No. 2014/050697 Japanese Patent Application Laid-Open No. 2004-106376

The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a roll of a PVA film in which the PVA film is thin and wrinkles and eccentricity are not generated even when the winding length is long, and the appearance is good.

As a result of intensive studies to solve the above problems, the present inventors have found out that the above problem is solved by setting the interval (thickness of the air layer) between the PVA films wound on the roll to a specific range, and based on the knowledge, As a result of extensive studies, the present invention has been completed.

That is,

[1] A roll formed by winding a PVA film having a thickness of 45 탆 or less and a length of 2,000 m or more, the roll having an average gap between adjacent films of 5 탆 or less;

[2] The roll described in [1] above, wherein the width of the PVA film is 2 m or more;

[3] The roll according to the above [1] or [2], 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 [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], wherein the PVA film is a raw film for producing an optical film;

[7] The roll described in the above [6], wherein the optical film is a polarizing film;

[8] A process for producing a roll comprising a polyvinyl alcohol film having a thickness of 45 μm or less and a length of 2,000 m or more,

(a) In a winding process of a polyvinyl alcohol film, a contact roll disposed substantially parallel to the axial direction of the film roll is brought into contact with the outer circumferential face of the film roll formed of the already wound polyvinyl alcohol film, Is wound up,

(b) the pressure between the film roll and the contact roll is 3 to 30 N per 1 m in the axial direction of the film roll,

(c) the winding speed is 30 m / min or less;

[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 production method according to the above [8] or [9], 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;

Wherein the film roll and the contact roll have a 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 0.2 mm or less, as measured in the horizontal direction of the film roll and the horizontal direction of the contact roll, 8] to [10];

[12] The production method according to any one of [8] to [11], wherein an average interval between neighboring films in a roll obtained by winding a polyvinyl alcohol film is 5 m or less;

.

According to the present invention, there is provided a roll of a PVA film having a good appearance even when the PVA film is thin and the winding length is long. According to the production method of the present invention, such a roll can be efficiently produced.

1 is a schematic view showing an example of a touch winding method.
2 is a schematic view showing an example of a near-reel winding method.
Fig. 3 is a sectional view of the film roll 1 viewed from the direction 11 of the tangent line 10 of the contact roll 2 at a position where the contact roll 2 is in contact with the film roll 1 Is an example of a schematic view of the contact roll 2.
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.

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

When the roll of the present invention is obtained by winding the PVA film, it is preferable to wind the PVA film on the cylindrical core from the viewpoints of the quality and handleability of the obtained roll. There is no particular limitation on the type of core used, and examples thereof include metal, plastic, paper, and wood. In addition, 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. Of these, the use of a metal and / or a plastic material is preferred because of its high strength, the effect of the present invention being more remarkably obtained, and the generation of dust which is a problem in production of an optical film such as a polarizing film. Is preferable, and a metal core is more preferable because it is not easily affected by wear or the like even if it is repeatedly used. The ratio of the mass of the metal and the plastic to the total mass of the core is preferably 50 mass% or more, more preferably 80 mass% or more, further preferably 95 mass% or more, and 100 mass% Particularly preferred.

Examples of the metal include iron, stainless steel, and aluminum. One of these metals may be used alone, or two or more metals may be used in combination. Of these, aluminum and iron are preferable from the viewpoints of strength, light weight, cost, and the like.

Examples of the plastic include polyvinyl chloride, polyvinylidene chloride, polyester, polycarbonate, polyamide, epoxy resin, polyurethane, polyurea, silicone resin and the like. May be used alone, or two or more of them may be used in combination. Of these, polyvinyl chloride is preferable. It is also preferable that the plastic is a fiber reinforced plastic (FRP) such as carbon fiber reinforced plastic from the viewpoint of strength and the like.

There is no particular limitation on the length of the cylindrical core, but from the viewpoint of handleability and the like, the winding is preferably long in the range of 5 to 100 cm from the width of the PVA film, and is long in the range of 10 to 45 cm More preferably in the range of 15 to 30 cm.

The diameter of the core is not particularly limited, but it is preferably within the range of 50 to 800 mm, more preferably within the range of 80 to 500 mm, more preferably within the range of 100 to 300 Mm, more preferably in the range of 150 to 250 mm. From the viewpoints of strength, handling property, and the like, the cylindrical core preferably has a thickness in the range of 2 to 50 mm, more preferably in the range of 3 to 20 mm, more preferably in the range of 4 to 10 mm desirable.

Examples of the PVA constituting the PVA film used in the present invention include unmodified PVA obtained by saponifying a polyvinyl ester obtained by polymerizing a vinyl ester, modified PVA obtained by graft copolymerizing a comonomer with a main chain of the PVA, A modified PVA obtained by saponifying a modified polyvinyl ester obtained by copolymerizing an ester and a comonomer, a so-called polyvinyl acetal resin obtained by crosslinking a part of the hydroxyl groups of unmodified PVA or modified PVA with aldehydes such as formalin, butylaldehyde, and benzaldehyde . When the PVA constituting the PVA film is a modified PVA, the amount of modification in the PVA is preferably 15 mol% or less, more preferably 5 mol% or less.

Examples of the vinyl ester used for producing PVA include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, vinyl laurate, vinyl stearate, vinyl benzoate, Vinyl acetate, and the like. These vinyl esters can be used singly or in combination. Among these vinyl esters, vinyl acetate is preferable from the viewpoint of productivity.

Examples of the comonomer include olefins having 2 to 30 carbon atoms (e.g.,? -Olefins, etc.) such as ethylene, propylene, 1-butene and isobutene; Acrylic acid or a salt thereof; Acrylic esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate and octadecyl acrylate For example, C1-18 alkyl esters of acrylic acid, etc.); Methacrylic acid or a salt thereof; Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2- Methacrylic acid esters such as ethylhexyl, octadecyl methacrylate and the like (for example, alkyl esters having 1 to 18 carbon atoms in methacrylic acid and the like); Acrylamide; N, N-dimethylacrylamide, diacetone acrylamide, acrylamidepropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or a salt thereof, N-methylolacrylamide or An acrylamide derivative such as a derivative; Methacrylamide; Methacrylamide derivatives such as N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamide propanesulfonic acid or salts thereof, methacrylamidopropyldimethylamine or salts thereof, N-methylolmethacrylamide or derivatives thereof; N-vinyl amides such as N-vinyl formamide, N-vinyl acetamide and N-vinyl pyrrolidone; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether Ethers; Nitriles such as acrylonitrile and methacrylonitrile; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; Allyl compounds such as allyl acetate and allyl chloride; Unsaturated dicarboxylic acids such as maleic acid and itaconic acid, and salts and esters thereof; Vinylsilyl compounds such as vinyltrimethoxysilane; Isopropenyl acetate; Unsaturated sulfonic acid or a derivative thereof. These comonomers may be used singly or in combination of two or more. Among these comonomers,? -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 even more preferably 2,000 or more, from the viewpoint of the polarizing performance and durability of the resulting polarizing film. From the viewpoints of ease of production and elongation property for producing a homogeneous PVA film, the degree of polymerization of PVA is preferably 8,000 or less, more preferably 6,000 or less. The degree of polymerization of PVA in the present specification refers to an average degree of polymerization measured according to the description of JIS K6726-1994. The degree of polymerization of PVA is obtained from the intrinsic viscosity measured in water at 30 캜 after re-saponification and purification of PVA.

The saponification degree of PVA is preferably 95 mol% or more, more preferably 98 mol% or more, and still more preferably 99 mol% or more from the viewpoint of the polarizing performance and durability of the obtained polarizing film. The saponification degree of PVA in the present specification means the ratio of the number of moles of the vinyl alcohol unit to the total mole number of the structural unit (typically, vinyl ester unit) that can be converted into the vinyl alcohol unit by saponification and the vinyl alcohol unit Mol%). The saponification degree of PVA can be measured in accordance with the description of JIS K6726-1994.

The PVA constituting the PVA film may be one kind of PVA or two or more types of PVA differing in one or more than two from among the degree of polymerization, the degree of saponification, the degree of modification and the like. The content of PVA in the PVA film is preferably within a range of 50 to 100 mass%, more preferably within a range of 80 to 100 mass%, and still more preferably within a range of 85 to 100 mass%.

It is possible to improve the mechanical properties such as impact strength and the like and to improve the processability and the stretchability at the time of secondary processing and to obtain the roll of the present invention more efficiently. . Preferable plasticizers include polyhydric alcohols. Specific examples thereof include ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane and the like. The PVA film may contain one or more of these plasticizers. Among these plasticizers, one or two or more of glycerin, diglycerin and ethylene glycol are preferably used, and glycerin is more preferably used from the viewpoint of the effect of improving the stretchability when the PVA film is stretched and used.

The content of the plasticizer in the PVA film is preferably in the range of 1 to 30 mass%. When the content of the plasticizer in the PVA film is less than 1% by mass, the flexibility of the film is insufficient, which tends to cause a problem that the film is cracked at the time of winding or the stretchability at the time of polarizing plate is deteriorated. From this point of view, the content is more preferably 5% by mass or more, and still more preferably 10% by mass or more. When the content of the plasticizer in the PVA film is more than 30% by mass, bleeding-out occurs during storage of the roll, resulting in uneven physical properties in the surface of the PVA film, It is liable to cause problems to occur. From such a viewpoint, the content is more preferably 20 mass% or less, and still more preferably 15 mass% or less.

The PVA film preferably contains a surfactant from the viewpoints of handling properties and improvement of peelability from the film forming apparatus when the PVA film is produced. The kind of the surfactant is not particularly limited, and examples thereof include anionic surfactants and nonionic surfactants.

Examples of the anionic surfactant include carboxylic acid type such as potassium laurate; Sulfuric acid ester type such as octylsulfate; And sulfonic acid type such as dodecylbenzenesulfonate.

Examples of the nonionic surfactants include alkyl ether types such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; Alkyl phenyl ether type such as polyoxyethylene octyl phenyl ether; Alkyl ester types such as polyoxyethylene laurate; Alkylamine type such as polyoxyethylene lauryl amino ether; Alkyl amide types such as polyoxyethylene lauric acid amide; Polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; Alkanolamide types such as diethanolamide laurate, and diethanolamide oleic acid; And allyl phenyl ether type such as polyoxyalkylene allyl phenyl ether.

The PVA film may contain one or more of these surfactants. Among these surfactants, a nonionic surfactant is preferable, an alkanolamide surfactant is more preferable, and an aliphatic carboxylic acid (for example, a saturated aliphatic carboxylic acid having a carbon number of 8 (E.g., a saturated or unsaturated aliphatic carboxylic acid of? 30), and the like are more preferable.

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 content of the surfactant is too small, there is a possibility that handling properties of the PVA film and detachability from the film-forming apparatus at the time of producing the PVA film become worse or blocking may occur. From this viewpoint, the content of the surfactant is more preferably 0.02% by mass or more, and still more preferably 0.05% by mass or more. On the other hand, if the content ratio of the surfactant is excessively high, the film is likely to bleed out to deteriorate the uniformity of the film, thereby causing optical unevenness in the obtained polarizing plate, or a problem of deteriorating the transparency of the film. From this viewpoint, the content of the surfactant is more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less.

The PVA film may further contain other components such as an antioxidant, an ultraviolet absorber, a lubricant, a colorant, an antiseptic, an antiseizing agent, a polymer compound other than the above-mentioned components, and water, if necessary. The PVA film may 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 the width of the film after film formation are more uniform can be preferably employed. For example, the PVA constituting the PVA film and the plasticizer, , A surfactant, and one or more of the above-mentioned other components dissolved in a liquid medium, PVA, and if necessary, one or more of a plasticizer, a surfactant, , And PVA is molten. In the case where the stock solution for film formation contains at least one of a plasticizer, a surfactant and the other components, it is preferable that the components are uniformly mixed.

Examples of the liquid medium used for the preparation of the film-forming solution include water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, Triethylene glycol, tetraethylene glycol, trimethylol propane, ethylenediamine, diethylenetriamine, and the like, and one or more of these may be used. Among them, water and dimethylsulfoxide are preferable, and water is more preferable.

The volatile matter content of the undiluted film forming solution (the content ratio of volatile components such as a liquid medium removed by volatilization or evaporation at the time of film forming in the film-forming stock solution) varies depending on the polymerization degree of PVA, the film-forming method, More preferably 25 mass% or more, further preferably 30 mass% or more, particularly preferably 40 mass% or more, further preferably 95 mass% or less, more preferably 90 mass% or less By mass, more preferably 85% by mass or less, and particularly preferably 70% by mass or less. Since the volatile fraction of the undiluted film forming solution is lower than the lower limit described above, the viscosity of the undiluted film forming solution does not become excessively high, and filtration and defoaming at the time of preparation of the film forming solution are smoothly performed. On the other hand, when the volatile fraction of the film-forming raw liquid is not more than the upper limit, the concentration of the film-forming stock solution is not excessively lowered, and the production of an industrial PVA film is facilitated.

Examples of the film forming method for forming the PVA film using the above-mentioned 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 employ only one type, or two or more types may be used in combination. 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 a specific example of the production method of the PVA film, there is known a film-like discharging device (film-like flexible device) such as a T-shaped slit die, a hopper plate, an I-die and a lip coater die, (Or belt) on the circumferential surface of the first roll (or belt), which is located on the first roll (or belt), and the volatile component Drying is further carried out on the circumferential surface of one or a plurality of rolls heated and rotated on the downstream side thereof or passed through a hot air drying apparatus in an industrially preferable manner . The drying by the heated roll and the drying by the hot air drying apparatus may be carried out in appropriate combination.

The thickness of the PVA film in the roll of the present invention is required to be 45 占 퐉 or less. When the thickness of the PVA film is 45 占 퐉 or less, a thin polarizing film can be efficiently produced. By using such a thin polarizing film, a thin polarizing plate can be efficiently produced. Conventionally, when the PVA film is thin and the winding length is long, fine wrinkles or eccentricity are generated, and there is a problem that a roll having a good outer appearance is not obtained. On the other hand, according to the present invention, even if the PVA film is thin and the winding length is long, wrinkles and eccentricity are not generated well, and a roll of the PVA film having a good outer appearance is obtained. Therefore, the effect of the present invention is remarkably obtained when the thickness of the PVA film is 45 mu m or less. In view of the above, the thickness of the PVA film is preferably 40 占 퐉 or less, more preferably 35 占 퐉 or less, more preferably 30 占 퐉 or less, particularly preferably 25 占 퐉 or less, and most preferably 20 占 퐉 or less. On the other hand, if the thickness of the PVA film is too thin, secondary processing of a film processed with an optical film such as a polarizing film tends to be difficult. Therefore, the thickness is preferably 1 占 퐉 or more, more preferably 3 占 퐉 or more, further preferably 5 占 퐉 or more, and particularly preferably 10 占 퐉 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, needs to be 2,000 m or more. Since the length of the PVA film is 2,000 m or more, even if the optical film such as the polarizing film to be produced is large, it is possible to continuously produce the optical film having excellent uniformity of optical performance with good efficiency. Further, conventionally, when the PVA film is thin and the winding length is long, fine wrinkles or eccentricity are generated, and there is a problem that a roll having a good outer appearance is not obtained. On the other hand, according to the present invention, even if the PVA film is thin and the winding length is long, wrinkles and eccentricity are not generated well, and a roll of the PVA film having a good outer appearance is obtained. Therefore, the effect of the present invention is remarkably obtained when the length of the PVA film is 2,000 m or more. In view of the above, the length of the PVA film is preferably 3,000 m or more, more preferably 4,000 m or more, still 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, but the length is preferably 30,000 m or less, and more preferably 22,000 m or less in view of easily obtaining a roll of the PVA film having a better appearance. The length of the PVA film may be less than 18,000 m, or even less than 15,000 m.

The width of the PVA film is not particularly limited, and may be, for example, 50 cm or more. However, the wider the width of the PVA film, the wrinkles and eccentricity tend to be easily generated in the obtained roll. On the other hand, according to the present invention, even when the width of the PVA film is wide, the occurrence of wrinkles and eccentricity is reduced, and the effect of the present invention is more remarkably obtained in such a case. Further, by using a wide PVA film, it is possible to manufacture a wide polarizing film capable of coping with the large screen of an LCD. In these points, 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. Although the upper limit of the width of the PVA film is not particularly limited, the width is preferably 6 m or less, more preferably 5 m or less, and more preferably 4.2 m or less in view of easily obtaining a roll of the PVA film having a better appearance profile desirable. The PVA film is preferably 4 m or less, more preferably 3.8 m or less in view of obtaining a PVA film having particularly excellent appearance.

In the roll of the present invention, the average spacing between adjacent films (between PVA films adjacent to each other in the radial direction of the roll) needs to be 5 占 퐉 or less. The average distance corresponds to the thickness of the air layer between the films. When the average interval is 5 占 퐉 or less, wrinkles and eccentricity are not generated even when the PVA film is thin and the winding length is long, so that a roll having good appearance can be obtained. From this viewpoint, the average spacing is preferably 4.9 占 퐉 or less, more preferably 4.5 占 퐉 or less, more preferably 4.2 占 퐉 or less, or 4 占 퐉 or less, further 3.8 占 퐉 or less. If the average distance between neighboring films is less than 2 탆, blocking may occur and fluctuations may occur in the roll of the PVA film, or the PVA film roll may be wound tightly to cause appearance abnormality such as wrinkles on the film It is likely to cause problems that the uniformity is hindered. From such a viewpoint, the average spacing is preferably at least 2 mu m, more preferably at least 2.5 mu m, even more preferably at least 3 mu m, and particularly preferably at least 3.5 mu m.

The average distance between adjacent films can be obtained by the following method. Namely, the average spacing N (m) between the neighboring films in an outer diameter H (m) roll formed by winding a PVA film having a length L (m) and a thickness M (占 퐉) on a cylindrical core of an outer diameter D ) Is expressed by the following formula:

N = {(? / 4) (H ² - D ² ) / L} × 10 ⁶ - M

As shown in FIG.

The production method of the roll of the present invention is not particularly limited, but the production method of the present invention described below is preferable because the roll can be efficiently produced. That is, the production method of the present invention is a production method of a roll obtained by winding a PVA film having a thickness of 45 μm or less and a length of 2,000 m or more,

(a) In a winding process of a PVA film, a contact roll disposed substantially parallel to the axial direction of the film roll is formed on the outer circumferential face of a film roll (film state portion) formed of a previously wound PVA film, Winding,

(b) the pressure between the film roll and the contact roll is 3 to 30 N per 1 m in the axial direction of the film roll,

(c) the winding speed is 30 m / min or less.

In the production method of the present invention, the PVA film used in the production of rolls may be those described above as the PVA films used in the production of rolls of the present invention.

In the manufacturing 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 formed on the outer peripheral surface of the film roll formed by the already wound PVA film, A touch winding method is adopted. 1 is a schematic view showing an example of the touch winding method. As shown in Fig. 1, on the outer circumferential surface of the film roll 1 formed by the already wound PVA film 3, a contact roll 2 arranged substantially parallel to the axial direction of the film roll 1 The PVA film 3 is further wound in a direct contact state to produce a roll. As the contact roll 2 to be used, a film longer than the axial length of the film roll 1 can be used. It is preferable that the film roll 1 and the contact roll 2 are in contact with each other over the entire axial direction of the film roll 1 at the position 5 where the PVA film 3 is wound around the film roll 1 Do. In addition, as a method separate from the touch winding method, a near winding method, which is schematically shown in Fig. 2, is known. 2, when the PVA film 3 is wound, a space (gap) is formed between the outer circumferential surface of the film roll 1 formed of the already wound PVA film and the contact roll 2 .

The length of the contact roll 2 is not particularly limited but is preferably long within a range of 3 to 200 cm from the width of the film roll 1, more preferably within a range of 5 to 100 cm, More preferably in the range of 50 cm to 50 cm.

Although the diameter of the contact roll 2 is not particularly limited, it is preferably within the range of 50 to 1000 mm, more preferably within the range of 75 to 800 mm, more preferably within the range of 100 to 1000 mm, More preferably in the range of 125 to 350 mm, and particularly preferably in the range of 125 to 350 mm. The material of the surface layer of the contact roll 2 is not particularly limited and includes rubber, resin, metal and the like, among which rubber is preferable.

In the manufacturing method of the present invention, when the PVA film 3 is wound, the pressure between the film roll 1 and the contact roll 2 (the pressure that presses the contact roll 2 against the film roll 1) Is set within the range of 3 to 30 N per 1 m in the axial direction of the rotor (1). 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 direction of the film roll. By setting the rolling contact pressure within the above range, the roll of the present invention can be efficiently produced. From this viewpoint, the winding 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 of production of the roll of the present invention at a higher efficiency, it is preferably 3.5 N / m or more, more preferably 4 N / m or more.

In the production method of the present invention, the winding speed at the time of 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 efficiently produced. 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, more preferably 15 m / min or more.

In the manufacturing method of the present invention, the winding tension (the tensile force applied in the longitudinal direction of the PVA film 3 when the PVA film is wound when the PVA film 3 is wound) is compared with the film formed of the already wound PVA film It is preferable that the length of the roll 1 is 80 N or less per 1 m in the axial direction. Hereinafter, " N / m " may be used as a unit for indicating the winding tension per 1 m length of the film roll 1 in the axial direction. By setting the winding tension within the above range, the roll of the present invention can be produced more efficiently. From this viewpoint, the coiling tension is more preferably 75 N / m or less, and more 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, still more preferably 45 N / m or more, and 50 N / m or more.

Fig. 3 is a sectional view of the film roll 1 viewed from the direction 11 of the tangent line 10 of the contact roll 2 at a position where the contact roll 2 is in contact with the film roll 1 Is an example of a schematic view of the contact roll 2. The parallelism A between the axis of the film roll 1 and the axis of the contact roll 2, which is obtained by the distance between the axis of the film roll 1 and the axis of the contact roll 2, is 0.7 mm Or less. This makes it easy for the film roll 1 and the contact roll 2 to contact over the entire axial direction of the film roll 1 at the position 5 where the PVA film 3 is wound around the film roll 1 It is possible to produce the roll of the present invention having a good outer shape with better efficiency. 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 a distance (b - a) from the one end (b) of the shaft 7 of the contact roll 2 to the shaft 6 of the film roll 1, (B '- a') from the other end b 'of the shaft 7 of the film roll 1 to the shaft 6 of the film roll 1. One end b of the shaft 7 of the contact roll 2 is located closest to the end 8 of the PVA film 3 and the other end b ' Make the closest position. Distance (b - a) and 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 manufacturing method of the present invention, the film roll 1 and the contact roll 2, which are obtained from the horizontal direction of the axis of the film roll 1 and the horizontal direction of the contact roll 2, The parallelism (B) between the axis of the roll 1 and the axis of the contact roll 2 is preferably 0.2 mm or less. This makes it easy for the film roll 1 and the contact roll 2 to contact over the entire axial direction of the film roll 1 at the position 5 where the PVA film 3 is wound around the film roll 1 It is possible to produce the roll of the present invention having a good outer shape with better efficiency. 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 which includes the axis 6 of the film roll 1 and which is also perpendicular to the horizontal plane. The distance d-c from the one end d of the shaft 7 of the contact roll 2 to the shaft 6 of the film roll 1 on the projection surface and the distance d- (D '- c') from the other end d 'of the film roll 1 to the shaft 6 of the film roll 1 is referred to as parallelism (B). One end d of the shaft 7 of the contact roll 2 is located closest to the end 8 of the PVA film 3 and the other end d ' Make the closest position. The parallelism B can be obtained by measuring the horizontal degree of the film roll 1 and the contact roll 2 in the axial direction by using a leveling unit.

In the roll obtained as described above, it is preferable that the average distance between neighboring films is 5 占 퐉 or less. When the average interval is 5 占 퐉 or less, wrinkles and eccentricity are not generated even when the PVA film is thin and the winding length is long, so that a roll having good appearance can be obtained. According to the production method of the present invention, it is possible to easily control the average interval. The average spacing is preferably 4.9 占 퐉 or less, more preferably 4.5 占 퐉 or less, further preferably 4.2 占 퐉 or less, or 4 占 퐉 or less, further 3.8 占 퐉 or less. On the other hand, the average interval is preferably 2 m or more, more preferably 2.5 m or more, further preferably 3 m or more, and particularly preferably 3.5 m or more.

The use of the PVA film in the roll of the present invention is not particularly limited, and examples thereof include a film for packaging pharmaceutical products, a base film for hydraulic transfer, a base film for embroidery, a release film for molding artificial marble, a film for seed packaging, And can be used for various kinds of water-soluble films such as film for film. According to the present invention, even if the PVA film is thin and the winding length is long, wrinkles and eccentricities are not generated well, and a roll having good appearance is provided. By using such a roll, it is possible to continuously produce an optical film having a large area and excellent optical performance uniformity with good efficiency. Therefore, the PVA film is preferably used 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 subjecting the PVA film to a treatment such as uniaxial stretching.

The method for producing the polarizing film using the PVA film is not particularly limited and any conventionally known method may be employed. According to such a method, for example, a PVA film wound from the roll of the present invention is used for dyeing and uniaxial stretching, or for a PVA film containing a dye wound from the roll of the present invention, Or the like. As a more specific method for producing the polarizing film, the PVA film extruded from the roll of the present invention may be subjected to swelling, dyeing, uniaxial stretching and, if necessary, further crosslinking treatment, fixing treatment, 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 may be performed at the same time. In addition, one or two or more of the processes may be performed twice or more.

The produced polarizing film is usually used in the form of a polarizing plate by kneading a protective film having optical transparency and mechanical strength on one side or both sides thereof. As the protective film, a cellulose triacetate (TAC) film, a cycloolefin polymer (COP) film, an acetic acid-butyric acid cellulose (CAB) film, an acrylic film, a polyester film and the like are used. As the adhesive for adhering, PVA adhesive, urethane adhesive and the like can be mentioned. Among them, PVA adhesive is preferable.

The polarizing plate obtained as described above can be used as an LCD component after being coated with a pressure-sensitive adhesive such as an acryl-based adhesive and then adhered to a glass substrate. At the same time, it may be laminated with a retardation film, a viewing angle improving film, a luminance improving film or the like.

[Example]

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

[Evaluation of appearance shape]

The appearance of rolls was evaluated according to the following criteria.

A: No appearance of wrinkles or eccentricity, and good appearance

B: Very few wrinkles were found, but there was no eccentricity and the appearance was good.

C: Fine wrinkles and eccentricity are generated, resulting in poor appearance

[Evaluation of optical unevenness]

A sample film of 15 cm x 5 cm was 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 subjecting the PVA film to a swelling process, a dyeing process, a crosslinking process, a stretching process, a fixing process and a drying process. Four sample films were attached to the stretching jig. (First-stage stretching) in the longitudinal direction (MD) at 2.2 times the original length while immersed in water at 30 캜 for one minute. Thereafter, while immersing in a dyeing bath at a temperature of 30 ° C containing iodine in an amount of 0.03 mass% and potassium iodide in a concentration of 3.0 mass% for 2 minutes, uniaxial stretching in the machine direction (MD) to 3.2 times the original length Second-stage stretching). While this was immersed in a crosslinking bath having a concentration of 3.0% by mass of boric acid and 3.0% by mass of potassium iodide for 2 minutes, uniaxial stretching in the longitudinal direction (MD) to 3.6 times of the original length ). Further, uniaxial stretching (stretching at the fourth stage) was carried out while immersing in a drawing bath at a temperature of 55 DEG C containing boric acid at 4.0 mass% and potassium iodide at a concentration of 5.0 mass%, and when two of the four films were cut Were taken out of the drawing bath. Thereafter, the film was immersed in a fixed treatment bath having a concentration of 1.5 mass% boric acid and 5 mass% potassium iodide at a temperature of 22 캜 for 5 seconds, followed by drying for 240 seconds in a drier at 60 캜, To prepare a polarizing film.

A sample film having a size of 5 cm x 5 cm was sampled from the central portion of the obtained polarizing film and placed on a single polarizing plate (43.5% of simple transmittance and 99.9% of polarization degree) in a cross-Nicol state. Using a backlight of a luminance of 15,000 candela, the difference in light and darkness resulting from the non-uniformity (optical non-uniformity) of the transmittance between the film collected from the center portion of the film roll and the film collected from the end portion was observed and optical unevenness was evaluated based on the following criteria .

A: There is no difference in light and shade due to the difference in transmittance between the film taken from the center and the film taken from both ends, and is uniform.

B: There is a slight difference between light and shade due to the difference in transmittance between the film taken from the center and the film taken from both ends.

C: There is a clear difference in contrast between the film taken from the center and the film taken from both ends.

Example 1

(Having a thickness of 30 占 퐉, a length of 20,000 m, a width of 4.2 m, a content of glycerin of 10% by mass as a plasticizer and a content of 0.1% by mass of lauric acid diethanolamide as a surfactant) ) Was wound around a cylindrical core to prepare a roll. Further, as a winding method, a contact roll (outer diameter: 210 mm, roll length: 4950 mm) arranged substantially parallel to the axial direction of the film roll was brought into contact with the outer circumferential face of the film roll formed of the already wound PVA film 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 mu m. The appearance of the roll was evaluated by the above method. In addition, the polarizing film was produced and the optical non-uniformity was evaluated by the above method. Table 1 shows the above results.

Examples 2 to 8 and Comparative Examples 2 to 5

Production and evaluation of a roll were carried out in the same manner as in Example 1 except that the thickness, length, width, plasticizer content and surfactant content of the PVA film used in the rolls, and the production conditions of the rolls were changed as shown in Table 1 Respectively. The results are shown in Table 1.

[Comparative Example 1]

(Having a thickness of 30 占 퐉, a length of 20,000 m, a width of 3.3 m, a content of glycerin of 10% by mass as a plasticizer and a content of 0.1% by mass of lauric acid diethanolamide as a surfactant) having a degree of polymerization of 2,400 and a degree of saponification of 99% ) Was wound around a cylindrical core to prepare a roll. In addition, as a winding system, a near winding system was adopted. Specific conditions are shown below.

[Contact roll]

Shaft Diameter: 210 mm

Roll length: 4950 mm

[Winding condition]

Winding contact pressure: None (Near wind up method)

Winding speed: 24 m / min

Coiling tension: 100 N / m

Parallelism: 0.8 mm

Horizontal degree: 0.2 mm

The obtained rolls were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Referential Example 1]

(Having a thickness of 60 占 퐉, a length of 9,600 m, a width of 4.2 m, 10 mass% of glycerin as a plasticizer, and 0.1 mass% of lauric acid diethanolamide as a surfactant) having a degree of polymerization of 2,400 and a saponification degree of 99 mol% ) Was wound around a cylindrical core to prepare a roll. In addition, as a winding system, a near winding system was adopted. Specific conditions are shown below.

[Contact roll]

Shaft Diameter: 210 mm

Roll length: 4950 mm

[Winding condition]

Winding contact pressure: None (Near wind up method)

Winding speed: 12 m / min

Winding tension: 52 N / m

Parallelism: 0.8 mm

Horizontal degree: 0.2 mm

The obtained rolls were evaluated in the same manner as in Example 1. The results are shown in Table 1.

1: film roll
2: contact roll
3: PVA film
4: Core
5: Position where PVA film is wound
6: Axis of film roll
7: Axis of contact roll
8, 9: End of PVA film
10: Tangent
11, 12: direction

Claims (12)

A roll wherein a polyvinyl alcohol film having a thickness of 45 μm or less and a length of 2,000 m or more is wound, wherein the average interval between neighboring films is 5 μm or less. The method according to claim 1,
Wherein the average spacing between adjacent films is at least 2 占 퐉. 3. The method according to claim 1 or 2,
Wherein the content of the plasticizer in the polyvinyl alcohol film is 1 to 30% by mass. 4. The method according to any one of claims 1 to 3,
Wherein the content of the surfactant in the polyvinyl alcohol film is from 0.01 to 1.0% by mass. 5. The method according to any one of claims 1 to 4,
Wherein the width of the polyvinyl alcohol film is 2 m or more. 6. The method according to any one of claims 1 to 5,
Wherein the polyvinyl alcohol film is a fabric film for optical film production. The method according to claim 6,
Wherein the optical film is a polarizing film. A polyvinyl alcohol film having a thickness of 45 占 퐉 or less and a length of 2,000 m or more is wound,
(a) In a winding process of a polyvinyl alcohol film, a contact roll disposed substantially parallel to the axial direction of the film roll is brought into contact with the outer circumferential face of the film roll formed of the already wound polyvinyl alcohol film, Is wound up,
(b) the pressure between the film roll and the contact roll is 3 to 30 N per 1 m in the axial direction of the film roll,
(c) the winding speed is 30 m / min or less. 9. The method of claim 8,
Wherein the winding tension is 80 N or less per 1 m in the axial direction of the film roll. 10. The 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, 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. 11. The method according to any one of claims 8 to 10,
Wherein the parallelism B of 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 0.2 mm or less, which is obtained by the horizontal and vertical axes of the film roll and contact roll. The method according to any one of claims 8 to 11,
Wherein a mean interval between neighboring films in a roll obtained by winding a polyvinyl alcohol film is 5 占 퐉 or less.

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