JP2020023400A - Polyvinyl alcohol film roll - Google Patents

Abstract

To provide a polyvinyl alcohol film roll that enables widening and elongating of the polyvinyl alcohol film, allows the reeled-out film to be consistent film, and obtains deflecting film excellent in deflecting function and appearance property.SOLUTION: A polyvinyl alcohol film roll is formed by optical polyvinyl alcohol film wound on a cylindrical core tube. The core tube is formed of aluminum alloy that contains a specific amount each of silicon, iron, copper, manganese, magnesium, chrome, zinc, and titanium. The outer diameter, the cylindrical length, and the weight of the core tube are set in a specific range.SELECTED DRAWING: None

Description

  The present invention relates to a polyvinyl alcohol-based film roll, and more particularly, to a polyvinyl alcohol-based film roll obtained by winding a wide and long polyvinyl alcohol-based film.

  Conventionally, polyvinyl alcohol-based films have been used for various applications, and among them, useful films include optical films, particularly polarizing films.

  Usually, a polyvinyl alcohol-based film is commercialized by winding it around a cylindrical core tube after film formation.

  In recent years, as the screen size of a liquid crystal display device has increased, the size of a polyvinyl alcohol-based film has been required to be increased, particularly, the width thereof has to be 3 m or more. From the viewpoint of the property, a longer length such as 5000 m or more is required.

  The core tube for winding such a wide and long polyvinyl alcohol-based film is preferably a core tube using aluminum as a material in terms of the weight of the core tube itself, strength, cost, and the like. (For example, see Patent Documents 1 and 2).

JP 2004-106377 A JP 2001-315885 A

  By the way, in recent years, the size of the liquid crystal display device has been further increased, for example, from 32 inches to 52 inches. Along with this, it is necessary to further increase the width and length of the polyvinyl alcohol-based film, and in order to wind it into a product, it is also necessary to improve the core tube to withstand strength and bending. Have been.

Further, the polyvinyl alcohol-based film roll wound on the core tube is usually stored in a suspended state by supporting the core tube portion protruding outward from the roll end surface. There is a risk that the core tube may be bent or the perfect circle may be deformed due to local force in the part where the tube is supported, and from this point, improvement of the core tube for further enlargement is required. Can be
If the core tube is bent or the true circle is deformed, the core tube will be deformed and the feeding speed will be unstable due to eccentricity when the film is fed, causing problems such as film breakage and shearing. I do. Such a defect leads to the occurrence of a defect such as optical unevenness. If the deformation from the perfect circle is too large, it will be impossible to set even the production and maintenance.

  Under such a background, the present invention is a polyvinyl alcohol-based film roll corresponding to the widening and lengthening of the polyvinyl alcohol-based film, and the unwound film is a homogenous film, and has polarization performance and appearance characteristics. It is an object of the present invention to provide a polyvinyl alcohol-based film roll capable of obtaining a polarizing film having excellent characteristics.

  However, as a result of intensive studies conducted by the present inventors to achieve such an object, the inventors focused on an aluminum alloy used for the material of the core tube, and in the aluminum alloy, the content of components was set to a specific range. When the core tube is used, the core tube becomes excellent in deformation resistance and bending resistance. Further, even if the polyvinyl alcohol-based film wound around the core tube is widened and lengthened, the polyvinyl alcohol-based film is used. The film roll is excellent in deformation resistance and deflection resistance, and the film drawn out from the polyvinyl alcohol-based film roll is uniform, and the polarizing film made from the film has good polarizing performance and appearance characteristics. The present inventors have found that they are excellent, and have reached the present invention.

That is, the present invention is a polyvinyl alcohol-based film roll obtained by winding a polyvinyl alcohol-based film for optics around a cylindrical core tube, wherein the core tube is made of the following aluminum alloy (A) or (B). A polyvinyl alcohol-based film roll having an outer diameter of a core tube in a range of 150 to 300 mm, a cylindrical length of the core tube in a range of 2 to 7 m, and a mass of the core tube in a range of 30 to 150 kg. And
(A) The components contained are silicon 0.40-0.9% by weight, iron 0.35% by weight or less, copper 0.35% by weight or less, manganese 0.50% by weight or less, magnesium 0.40-0. 8% by weight, chromium 0.30% by weight or less, zinc 0.25% by weight or less, titanium 0.10% by weight or less, other components individually 0.05% by weight or less, total 0.15% by weight or less , An aluminum alloy in which the total of manganese and chromium is 0.5% by weight or less, and the balance thereof is aluminum.
(B) The components contained are silicon 0.40 to 0.8 wt%, iron 0.7 wt% or less, copper 0.15 to 0.40 wt%, manganese 0.15 wt% or less, magnesium 0.8 To 1.2% by weight, 0.04 to 0.35% by weight of chromium, 0.25% by weight or less of zinc, 0.15% by weight or less of titanium; An aluminum alloy weighing not more than .15 and the balance being aluminum.

  In the polyvinyl alcohol film roll of the present invention, the core tube is made of an aluminum alloy, and the aluminum alloy is set to the above (A) or (B), and the outer diameter of the core tube is 150 to 300 mm. . Therefore, even if the cylindrical length of the core tube is increased to 2 to 7 m, the core tube can be excellent in deformation resistance and bending resistance. Even if the width is increased to 6 m and the length is increased to 5000 to 20000 m, it is possible to obtain excellent deformation resistance and deflection resistance. As a result, in the polyvinyl alcohol-based film roll of the present invention, the film to be fed can be made uniform, and the polarizing film produced from the film can have excellent polarization performance and appearance characteristics.

  And the polarizing film using the homogeneous film drawn out from the polyvinyl alcohol-based film roll of the present invention has excellent polarizing performance and appearance characteristics.

  Next, embodiments of the present invention will be described in detail.

  One embodiment of the polyvinyl alcohol-based film roll of the present invention comprises a cylindrical core tube made of an aluminum alloy having a specific component, and a polyvinyl alcohol-based film wound around the outer peripheral surface of the core tube. I have.

  The aluminum alloy as the material of the core tube satisfies the above (A) or (B). With such specific components, the core tube has excellent deformation resistance and bending resistance. If these components are not contained, the strength of the core tube tends to decrease, and the deformation resistance and the bending resistance tend to decrease. Also, if the content of each component is too large, the effect of the present invention tends to be difficult to obtain.

  In particular, if the silicon content in the aluminum alloy component is too low, the core tube tends to have a reduced deformation resistance and deflection resistance. preferable.

  The dimensions of the core tube depend on the width and the like of the polyvinyl alcohol film to be wound, but the outer diameter is usually in the range of 150 to 300 mm, preferably in the range of 160 to 260 mm, and the cylindrical length ( (Axial length) is usually in the range of 2 to 7 m, preferably in the range of 3 to 6 m. The wall thickness of the core tube is usually preferably in a range of 3 to 40 mm, particularly preferably in a range of 5 to 30 mm, and more preferably in a range of 6 to 20 mm. Further, the mass of the core tube is in the range of 30 to 150 kg.

The core tube used in the present invention is an aluminum alloy containing each component as described above, and can be manufactured, for example, as follows.
That is, the ingot of the aluminum alloy containing each of the above components is usually heated to 400 to 600 ° C., and then extruded from a die under a high-pressure environment to form a cylinder.
After the aluminum alloy extruded at a high temperature is further returned to room temperature, the temperature is raised again to 170 to 180 ° C. and maintained for about 5 to 10 hours to perform an artificial age hardening treatment, or rapidly cooled (quenched) after the high temperature extrusion. ) May be subjected to an artificial age hardening treatment.

  On the other hand, the polyvinyl alcohol-based film is manufactured, for example, as follows. That is, the film is cast using an aqueous solution of a polyvinyl alcohol-based resin.

  As the polyvinyl alcohol-based resin, an unmodified polyvinyl alcohol-based resin, that is, a resin produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate is usually used. If necessary, a resin obtained by saponifying a copolymer of vinyl acetate and a small amount (for example, 10 mol% or less, preferably 5 mol% or less) of a copolymerizable component with vinyl acetate may be used. it can. Examples of the component that can be copolymerized with vinyl acetate include unsaturated carboxylic acids (including salts, esters, amides, and nitriles), and olefins having 2 to 30 carbon atoms (such as ethylene, propylene, n-butene, and isobutene). , Vinyl ethers, unsaturated sulfonates and the like.

  Further, as the polyvinyl alcohol-based resin, a polyvinyl alcohol-based resin having a 1,2-glycol bond in a side chain can be used. Examples of the polyvinyl alcohol-based resin having a 1,2-glycol bond in the side chain include (i) a method of saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene, and (ii) acetic acid. A method of saponifying and decarboxylating a copolymer of vinyl and vinylethylene carbonate, (iii) saponifying and depolymerizing a copolymer of vinyl acetate and 2,2-dialkyl-4-vinyl-1,3-dioxolane. It is obtained by a method of ketalization, (iv) a method of saponifying a copolymer of vinyl acetate and glycerin monoallyl ether, and the like.

  The weight average molecular weight of the polyvinyl alcohol resin is preferably in the range of 80,000 to 300,000, more preferably 110,000 to 260,000, and still more preferably 130,000 to 200,000. If the weight average molecular weight is too small, there is a tendency that sufficient optical performance is not obtained when the polyvinyl alcohol-based resin is used as an optical film, and if it is too large, stretching becomes difficult when the film is used as a polarizing film, and industrially Production tends to be difficult. The weight average molecular weight of the polyvinyl alcohol-based resin is measured by a GPC-LALLS method.

  Further, the average saponification degree of the polyvinyl alcohol-based resin is preferably 80 mol% or more, more preferably 85 to 100 mol%, and particularly preferably 98 to 100 mol%. Thus, if the average degree of saponification is too small, it tends to be difficult to obtain sufficient polarization performance when a polarizing film is formed.

  The aqueous polyvinyl alcohol-based resin solution preferably contains generally used plasticizers such as glycerin, diglycerin, triglycerin, ethylene glycol, triethylene glycol, polyethylene glycol, and trimethylolpropane. The content is preferably 30% by weight or less, particularly 3 to 25% by weight, and more preferably 5 to 20% by weight based on the polyvinyl alcohol resin. If the amount of the plasticizer is too large, the film strength tends to decrease.

  Further, it is preferable to contain a nonionic, anionic, or cationic surfactant, and particularly preferably a nonionic surfactant such as polyoxyethylene alkylamino ether. The content of such a surfactant is preferably 5% by weight or less, more preferably 0.001 to 3% by weight, and particularly preferably 0.001 to 2% by weight based on the polyvinyl alcohol resin. If the amount of the surfactant is too large, the appearance of the film surface tends to be poor.

  Sodium acetate contained in the polyvinyl alcohol-based resin powder is preferably removed (devinegarized) because it adversely affects optical performance. The removal (devinegarization) of sodium acetate is usually performed by adding water to the polyvinyl alcohol-based resin in a devinegarization tank.

Next, the aqueous polyvinyl alcohol-based resin wet cake after the washing is dissolved to prepare an aqueous solution of the polyvinyl alcohol-based resin. When the aqueous polyvinyl alcohol-based resin wet cake is directly dissolved in water, a desired high-concentration aqueous solution is obtained. Therefore, it is preferable to perform dehydration once. The dehydration method is not particularly limited, but a method using centrifugal force is generally used.
The washing and dehydration are preferably performed to obtain a wet polyvinyl alcohol resin wet cake having a water content of 50% by weight or less, preferably 30 to 45% by weight. If the water content is too high, it tends to be difficult to obtain a desired aqueous solution concentration.

  Then, water vapor (about 110 to 160 ° C.) is blown into the cake-like polyvinyl alcohol-based resin in the dissolving vessel to dissolve it under pressure to prepare an aqueous solution of the polyvinyl alcohol-based resin. At this time, a plasticizer, an additive, and the like are added as needed. Thereby, a polyvinyl alcohol-based resin aqueous solution having a water content of about 60 to 80% by weight is obtained.

  Next, the resulting aqueous polyvinyl alcohol resin solution is filtered to remove impurities, and then subjected to a defoaming treatment. As the defoaming method, a static defoaming method or a defoaming method using a multi-screw extruder is used, but a defoaming method using a multi-screw extruder is preferable.

  Next, the deaerated polyvinyl alcohol-based resin aqueous solution is filtered again, supplied to a T-shaped slit die, extruded from the T-shaped slit die, and allowed to flow down in a screen shape.

  The aqueous polyvinyl alcohol-based resin solution extruded from the T-shaped slit die and flowing down is cast, formed into a film, and dried on the outer peripheral surface of the rotating drum-type roll to form a film. Further, the drum type roll itself is usually at a high temperature (about 80 to 100 ° C.) for the film formation and drying.

  Next, the film is peeled off from the outer peripheral surface of the drum-type roll, and after passing through a plurality of drying rolls (about 60 to 100 ° C.) so that the front and back surfaces of the film pass alternately, preferably, a heat treatment machine ( 100-140 ° C). Then, put it on a humidity controller as needed. The water content of the film is preferably 5% by weight or less, particularly preferably 1 to 4% by weight. If the moisture content is too high, the appearance tends to be poor when the film is stored. Thus, the desired polyvinyl alcohol-based film is obtained. The dimensions of the obtained polyvinyl alcohol-based film are usually set in a range of 1.5 to 6 m in width and in a range of 5000 to 20,000 m in length.

Then, a core tube made of an aluminum alloy having the specific component is set in a winder. Next, the winding machine is driven to rotate the core tube, and the obtained polyvinyl alcohol-based film is wound around the outer peripheral surface of the core tube. Here, as described above, the core tube is made of an aluminum alloy having a specific component, so that the core tube has high strength, and is excellent in deformation resistance and deflection resistance. Thus, when the core tube is rotated by the above-described winding machine, the rotation deflection of the core tube is small, and the polyvinyl alcohol-based film can be wound in a uniform state without wrinkles or the like. Thereafter, if necessary, the wound polyvinyl alcohol-based film is cut into a product width by a slitter, and is wound again on the core tube. Thus, the polyvinyl alcohol-based film roll of this embodiment can be obtained.
In the present invention, when stored and transported as a product, it is also preferable that the core tube is used as the core tube of the polyvinyl alcohol-based film roll. In the winding before that, the core tube does not need to be the core tube as long as the core tube is small in rotational runout, has high strength, and has excellent deformation resistance and bending resistance. A different aluminum core tube or iron core tube can be used as appropriate.

  The polyvinyl alcohol-based film roll obtained in this manner is moved to a support table, and the left and right ends of the core tube are supported. Since the core tube is excellent in deformation resistance and deflection resistance as described above, the polyvinyl alcohol-based film roll obtained by winding the polyvinyl alcohol-based film around the core tube also has deformation resistance and deflection resistance. It has excellent properties and is supported without deformation or bending, or is stored or transported in a state where the amount of deformation or bending is small.

The polyvinyl alcohol-based film of the polyvinyl alcohol-based film roll is very useful as a material for forming an optical film, particularly, a polarizing film.
Thus, an example of a method for producing a polarizing film using the polyvinyl alcohol-based film will be described below.

  First, the polyvinyl alcohol-based film roll is set on the polarizing film manufacturing apparatus from the support table. Then, a polyvinyl alcohol-based film is fed from the polyvinyl alcohol-based film roll. At this time, as described above, since the polyvinyl alcohol-based film roll does not deform or bend, when the polyvinyl alcohol-based film is fed, the rotational fluctuation of the polyvinyl alcohol-based film roll is small, and The alcohol-based film can be fed out in a uniform state without wrinkles or breakage. Thereafter, the polyvinyl alcohol-based film is dyed, uniaxially stretched, and treated with a boron compound.

  The dyeing is performed by bringing a liquid containing iodine or a dichroic dye into contact with the polyvinyl alcohol-based film. Usually, an aqueous solution of iodine-potassium iodide is used. The concentration of iodine is 0.1 to 20 g / l, the concentration of potassium iodide is 10 to 70 g / l, and the mixture weight ratio of potassium iodide / iodine is iodine. The range of potassium iodide / iodine = 10 to 100 is preferable. The dyeing time is practically about 30 to 500 seconds, and the temperature of the dyeing bath is preferably 5 to 60C. Then, a small amount of an organic solvent compatible with water may be contained in addition to the water solvent. Further, as the contact means, any means such as immersion, coating, spraying and the like can be applied.

  The uniaxial stretching is preferably performed 3 to 10 times, more preferably 3.5 to 6 times. At this time, slight stretching (extending to the extent of preventing shrinkage in the width direction or more) may be performed in a direction perpendicular to the uniaxial stretching. The temperature conditions during uniaxial stretching are preferably set in the range of 40 to 170 ° C. Further, the uniaxial stretching ratio may be finally set in the above range, and the uniaxial stretching operation may be performed not only in one stage but also in any stage of the manufacturing process.

  The dyeing may be performed before the uniaxial stretching, at the same time as the uniaxial stretching, or after the uniaxial stretching. The dyeing is preferably performed before or at the same time as the uniaxial stretching.

  The boron compound treatment is a treatment for strengthening the dyeing, and is performed after or simultaneously with the dyeing and the uniaxial stretching, or simultaneously with the uniaxial stretching. As the boron compound, boric acid and borax are practical. The boron compound is used as an aqueous solution or a mixed solution of water and an organic solvent at a concentration of about 0.3 to 2 mol / l, and it is practically preferable to coexist a small amount of potassium iodide in the liquid. As a treatment method using the boron compound, a dipping method is preferable, but a coating method and a spraying method can also be used. The processing conditions are preferably a temperature of about 40 to 70 ° C. and a processing time of about 2 to 20 minutes, and it is also preferable to perform a stretching operation during the processing as necessary.

  The polarizing film thus obtained is, as described above, a polyvinyl alcohol-based film serving as a material of the polarizing film is fed out of the polyvinyl alcohol-based film roll in a uniform state without wrinkles or breakage. Therefore, it has excellent polarization performance and appearance characteristics.

  The polarizing film may be used as a polarizing plate by laminating and adhering an optically isotropic polymer film or sheet as a protective film to one or both surfaces thereof. Examples of the protective film include cellulose triacetate, cellulose diacetate, polycarbonate, polymethyl methacrylate, polystyrene, polyether sulfone, polyarylene ester, poly-4-methylpentene, polyphenylene oxide, and cycloolefin or norbornene polyolefin. Examples include films or sheets. Further, in order to reduce the thickness of the polarizing film, a curable resin such as a urethane resin, an acrylic resin, or a urea resin may be applied on one surface or both surfaces instead of the protective film and laminated. .

  Further, the above polarizing film (or a laminate in which a protective film or a curable resin is laminated on at least one surface thereof) has a transparent pressure-sensitive adhesive layer formed on one surface thereof by an ordinary method, if necessary, so that it can be used for practical use. In some cases, it is offered to Examples of the pressure-sensitive adhesive layer include acrylates such as butyl acrylate, ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, and acrylic acid, maleic acid, itaconic acid, methacrylic acid, crotonic acid, and the like. Mainly containing a vinyl monomer such as acrylonitrile, vinyl acetate, and styrene, which may interfere with the polarizing performance of the polarizing film. And particularly preferred. Other than this, any pressure-sensitive adhesive having transparency can be used. For example, a polyvinyl ether-based or rubber-based adhesive can be used.

  The polarizing film thus obtained can be used for, for example, liquid crystal displays (liquid crystal display devices such as electronic desk calculators, electronic watches, word processors, personal computers, personal digital assistants, instruments for automobiles and machinery), sunglasses, It is used for glare glasses, stereo glasses, reflection reducing layers for display elements (CRT, LCD, etc.), medical equipment, building materials, toys, and the like.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.
In the examples, “parts” and “%” mean on a weight basis.

[Example 1]
As shown below, after producing a core tube and a polyvinyl alcohol-based film, a polyvinyl alcohol-based film was wound around the outer peripheral surface of the core tube to produce a polyvinyl alcohol-based film roll. Then, a polarizing film was produced using the polyvinyl alcohol-based film of the polyvinyl alcohol-based film roll.

(Core tube)
A6N01 specified by JIS was selected as an aluminum alloy having a specific component as in the above-described embodiment, and a cylindrical core tube was manufactured using the material. Table 1 below shows the chemical components of the aluminum alloy A6N01. The dimensions of the core tube were 215 mm in outer diameter, 3500 mm in cylinder length, and 6 mm in wall thickness. The weight of the core tube was 37 kg.

(Polyvinyl alcohol film)
Using 100 parts of polyvinyl alcohol having a weight average molecular weight of 135000 and a saponification degree of 99.7 mol%, 12 parts of glycerin as a plasticizer, and 0.1 part of polyoxyethylene alkylamino ether as a surfactant (release agent), 35% After preparing a polyvinyl alcohol aqueous solution (including a plasticizer and a release agent as a solid content) having a concentration, the film is cast from a T-type slit die with a drum-type roll, dried, heat-treated, and humidified to perform a moisture content of 4%. A polyvinyl alcohol-based film having a width of 3000 mm and a thickness of 75 μm was produced.

(Preparation of polyvinyl alcohol-based film roll)
Then, the above polyvinyl alcohol-based film was wound on the outer peripheral surface of the core tube by 10,000 m. At this time, the winding tension (the tension per 1 m width of the polyvinyl alcohol-based film) was 130 N / m, and the winding speed was 80 m / min. The weight of the polyvinyl alcohol-based film roll after winding was 3000 kg.

(Preparation of polarizing film)
Thereafter, the wound-up polyvinyl alcohol-based film is unwound at a speed of 1.23 m / min, swollen in a washing tank (24 ° C.), and then swelled in an iodine tank (20 ° C., iodine 0.17 g / liter). Eight times, uniaxial stretching of 2.0 times in a boric acid bath (50 ° C., 8 ppm of iodine, 47 g / liter of boric acid), and further, a total of 5.2 times uniaxial stretching at a winding speed of 6.4 m / min. And a polarizing film.

[Example 2]
In Example 1 described above, the thickness of the core tube was set to 8 mm. The mass of the core tube was 50 kg. Other than that, it was the same as the above-mentioned Example 1.

[Example 3]
A6061 specified by JIS was selected as an aluminum alloy having a specific component as in the above-described embodiment, and a cylindrical core tube was manufactured using the material. Table 1 below shows the chemical components of the aluminum alloy A6061. The dimensions of the core tube were 233 mm in outer diameter, 4800 mm in cylinder length, and 15 mm in wall thickness. The mass of the core tube was 133 kg. As the polyvinyl alcohol-based film wound around the core tube, a polyvinyl alcohol-based film having a width of 4500 mm and a thickness of 60 μm was prepared. Further, the mass of the polyvinyl alcohol-based film roll was 3,600 kg. Other than that, it was the same as the above-mentioned Example 1.

[Comparative Example 1]
In Example 1, a core tube made of an aluminum alloy A6063 specified by JIS was prepared. The weight of the core tube was 37 kg. The weight of the polyvinyl alcohol-based film roll was 3000 kg. Other than that, it was the same as the above-mentioned Example 1.

[Comparative Example 2]
In Example 3, a core tube made of an aluminum alloy A6063 specified by JIS was prepared. The mass of the core tube was 133 kg. Further, the mass of the polyvinyl alcohol-based film roll was 3,600 kg. Except for this, the procedure was the same as in Example 3 above.

(Self-weight deflection of polyvinyl alcohol film roll)
The weight deflection of the polyvinyl alcohol-based film rolls of Examples 1 to 3 and Comparative Examples 1 and 2 (the deflection at the center when both pins were supported) was measured. The results are shown in Table 2 below.

[Presence or absence of wrinkles during winding of polyvinyl alcohol film]
The presence or absence of wrinkling of each polyvinyl alcohol-based film during winding was visually evaluated. As a result, those in which wrinkle formation was not confirmed were evaluated as ○ as excellent in homogeneity, and those in which wrinkle formation was confirmed were evaluated as x as inferior in homogeneity, and are shown in Table 2 below.

[Presence of streaks and uneven dyeing of polarizing film]
Streaks and uneven dyeing of the polarizing film were visually evaluated. As a result, those in which neither streaks nor uneven dyeing were confirmed were evaluated as ○ as excellent in appearance characteristics, and those in which either was confirmed were evaluated as x as inferior in appearance characteristics, and are shown in Table 2 below.

(Optical properties of polarizing film)
Optical characteristics (unit transmittance and degree of polarization) of the polarizing film were measured using "VAP-7070" manufactured by JASCO Corporation as a measuring device. In this measurement, five measurements were taken at equal intervals in the width direction of the polarizing film, and the maximum value, minimum value, and average value were shown in Table 2 below.
In addition, in the polyvinyl alcohol films of Comparative Examples 1 and 2, wrinkles occurred, and when the polarizing film was formed, uneven dyeing occurred. For this reason, in the plane of the film, there were places where the single transmittance and the degree of polarization were high and low, and a uniform film was not obtained.

  From the results shown in Table 2, in Examples 1 to 3, no wrinkles occurred in the polyvinyl alcohol-based film, and no streaks or uneven dyeing occurred in the polarizing film. On the other hand, in Comparative Examples 1 and 2, wrinkles occurred in the polyvinyl alcohol-based film, and the feeding of the polyvinyl alcohol-based film was not stable, and uniform stretching could not be performed. For this reason, uneven dyeing occurred. It can be understood that the cause is that the self-weight deflection of the polyvinyl alcohol-based film roll is larger in the comparative example than in Examples 1 to 3. In Examples 1 to 3, the optical characteristics (single transmittance and degree of polarization) of the polarizing film have little variation in the width direction and are excellent in in-plane uniformity. As a result, it is possible to improve the yield and respond to the quality of wide products. On the other hand, in Comparative Examples 1 and 2, since the variation in the width direction is large, the yield is reduced, and it is not possible to cope with a wide product. It can also be understood that the cause is that the self-weight deflection of the polyvinyl alcohol-based film roll is greater in Comparative Examples 1 and 2 than in Examples 1 to 3.

(Compression test)
Specimens made of the aluminum alloy constituting the core tubes of Examples 1 and 2 and Comparative Example 1 [width 40 mm, thickness is thickness of each example (Example 1 and Comparative Example 1: 6 mm, Example 2: 8 mm) Was prepared in each example, and a compression test was performed on each test piece using a tensile compression tester (100 KN, manufactured by Instron) under the following conditions. Then, a load at a displacement of 50 mm was measured, and an average value of three test pieces was calculated.
Bending speed: 10 mm / min
Test temperature: 23 ° C
Load cell used: 100kN
Compression distance: 80mm

  As a result, the average value of the load when the displacement was 50 mm was 3873 N for the test piece of Example 1, 6357 N for the test piece of Example 2, and 1797 N for the test piece of Comparative Example 1. That is, the compressive strength at the displacement of 50 mm is about 2.2 times that of the test piece of Example 1 and about 3.5 times that of the test piece of Example 2 as compared with the test piece of Comparative Example 1. .

  INDUSTRIAL APPLICABILITY The present invention is applicable to a case where a polarizing film having excellent polarization performance and appearance properties can be obtained from a polyvinyl alcohol-based film even if the film is made wider and longer.

Claims (1)

A polyvinyl alcohol-based film roll formed by winding a polyvinyl alcohol-based film for optics around a cylindrical core tube, wherein the core tube is made of the following aluminum alloy (A) or (B), and the outer diameter of the core tube is A polyvinyl alcohol-based film roll characterized by being in the range of 150 to 300 mm, the cylindrical length of the core tube being in the range of 2 to 7 m, and the mass of the core tube being in the range of 30 to 150 kg.
(A) The components contained are silicon 0.40-0.9% by weight, iron 0.35% by weight or less, copper 0.35% by weight or less, manganese 0.50% by weight or less, magnesium 0.40-0. 8% by weight, chromium 0.30% by weight or less, zinc 0.25% by weight or less, titanium 0.10% by weight or less, other components individually 0.05% by weight or less, total 0.15% by weight or less , An aluminum alloy in which the total of manganese and chromium is 0.5% by weight or less, and the balance is aluminum.
(B) The components contained are silicon 0.40 to 0.8 wt%, iron 0.7 wt% or less, copper 0.15 to 0.40 wt%, manganese 0.15 wt% or less, magnesium 0.8 To 1.2% by weight, 0.04 to 0.35% by weight of chromium, 0.25% by weight or less of zinc and 0.15% by weight or less of titanium; An aluminum alloy weighing not more than .15 and the balance being aluminum.