TWI609911B - Polyvinyl alcohol film roll and polarizing film using the film roll - Google Patents

Abstract

The invention provides a polyvinyl alcohol-based film roll capable of obtaining a polarizing film with excellent polarizing performance and appearance characteristics, which can prevent damage to the surface of the core tube, and the extracted film is a homogeneous film. This reel is a polyvinyl alcohol-based film roll made by winding a polyvinyl alcohol-based film for optics into a cylindrical core tube. The core tube is made of aluminum, and the surface of the core tube is Vickers. Hardness (HV) 400 or more.

Description

Polyvinyl alcohol film roll and polarizing film using the film roll

The present invention relates to a polyvinyl alcohol-based film roll, and more specifically, to a polyvinyl alcohol-based film roll wound with a wide and long strip of polyvinyl alcohol-based film, and using the film A polarizing film with excellent polarizing performance obtained on a roll.

Polyvinyl alcohol-based films have been used in various applications in the past, and among them, useful films include optical films, particularly polarizing films.

Generally, a polyvinyl alcohol-based film is rolled up into a cylindrical core tube after film formation, and the product is produced.

In recent years, with the enlargement of liquid crystal display devices, the size of polyvinyl alcohol-based films has been required to increase, in particular, a width of 3 m or more. Furthermore, when manufacturing polarizing films using polyvinyl alcohol-based films, from the viewpoint of productivity, Look, it is required to be longer than 5000m.

From the viewpoint of the weight, strength, and cost of the core tube itself, as the core tube for winding a wide and long strip of polyvinyl alcohol-based film, it is preferable to use a core tube made of aluminum (see, for example, Patent Document 1). And 2). [Known Technical Literature] [Patent Literature]

[Patent Document 1]: Japanese Patent Laid-Open No. 2004-106377 [Patent Document 2]: Japanese Patent Laid-Open No. 2001-315885

[Problems to be Solved by the Invention]

When the polyvinyl alcohol-based film is taken up or drawn out, the surface shape of the core tube affects the appearance of the film and the polarizing performance when used as a polarizing film. Furthermore, in the case where a polyvinyl alcohol-based film is used and only the core tube is stored or transported, there is a need to prevent the core tube from being damaged and maintain a good surface shape. In addition, when the polyvinyl alcohol-based film is left unused, although it is cut in parallel to the width direction of the film using a cutting blade to peel it off from the core tube, there is still a case where it is cut even after contacting it. It is necessary to maintain a good surface shape without damage to the core tube by the knife.

On the other hand, polyvinyl alcohol-based films are hydrophilic films. Compared with other hydrophobic films, they are more susceptible to moisture and other external factors. Therefore, they are also more likely to be affected by the surface shape of the core tube. Transfer to film. Therefore, it is necessary to review the core tube that is most suitable for polyvinyl alcohol film.

Under these backgrounds, an object of the present invention is to provide a polyvinyl alcohol-based film roll that can obtain a polarizing film with excellent polarizing performance and appearance characteristics, which can prevent damage to the surface of the core tube, and the extracted film is a homogeneous film. [Technical means to solve the problem]

However, the inventors of the present case conducted intensive research in order to achieve this purpose, and found the following, and then completed the present invention: consider the case where the material of the core pipe is aluminum, and make the surface of the core pipe Vickers hardness (HV) 400 or more, which can effectively prevent damage to the surface of the core tube, and can also improve the corrosion resistance, and the polyvinyl alcohol-based film roll formed by winding the polyvinyl alcohol-based film on the core tube is extracted. The thin film becomes a non-destructive and homogeneous thin film, and the polarizing film produced from the thin film becomes a polarizing film with excellent polarization performance and appearance characteristics.

That is, the first gist of the present invention is a polyvinyl alcohol-based film roll, which is configured by winding a polyvinyl alcohol-based film for optics into a cylindrical core tube made of an aluminum material, and the core The surface of the tube has a Vickers hardness (HV) of 400 or more; the second gist is a polarizing film obtained by using a polyvinyl alcohol-based film extracted from the polyvinyl alcohol-based film roll. [Effect of the present invention]

In the polyvinyl alcohol-based film roll of the present invention, the surface of the core tube has a Vickers hardness (HV) of 400 or more. Therefore, even when the remaining film is cut with a cutter or the like and peeled off, the cutter or the like contacts the core tube. In addition, when only the core pipe is stored or transported, the surface of the core pipe can be effectively prevented from being damaged, and in addition, it is excellent in weather resistance. As a result, the polyvinyl alcohol-based film roll of the present invention can make the extracted film a non-destructive homogeneous film, and the polarizing film made from the film can be a polarizing film with excellent polarizing performance and appearance characteristics.

In particular, when an anodized film is formed on the surface of the core tube by anodization, the hardness and strength of the core tube are increased, and damage to the surface of the core tube can be prevented.

Further, in the case of an aluminum-based aluminum alloy, the hardness and strength of the core tube are increased, and damage to the surface of the core tube can be prevented more effectively.

In addition, when the thickness of the anodized film formed on the surface of the core tube is 10 to 40 μm, the anodized film has an appropriate thickness for preventing damage to the surface of the core tube.

The polarizing film of the present invention is a non-destructive, homogeneous film extracted from the polyvinyl alcohol film roll of the present invention, so it can be a polarizing film with excellent polarizing performance and appearance characteristics.

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

One embodiment of the polyvinyl alcohol-based film roll of the present invention is composed of the following elements: a cylindrical core tube made of aluminum, and the surface of the core tube having a strength of 400 or more in Vickers hardness (HV); and polyethylene The alcohol-based film is wound around the outer peripheral surface of the core tube. In this way, the surface hardness of the core tube is prevented by setting the Vickers hardness (HV) of the surface of the core tube to 400 or more, and the polyvinyl alcohol-based film wound on the outer peripheral surface of the core tube is transferred without damage. The ground becomes a homogeneous film.

As the aluminum material which is the material of the core tube, aluminum or an aluminum alloy is used. Among them, from the viewpoint of improving the hardness and strength of the core pipe, an aluminum alloy is preferably used.

As this aluminum alloy, from the viewpoint of being excellent in deformation resistance and flex resistance, and corresponding to the widening of the polyvinyl alcohol-based film (widening of the core tube), it is desirable to make the 0.2% endurance 175 N / mm. ² or more, particularly preferably 175 to 600 N / mm ² , and more preferably 200 to 400 N / mm ² .

In the present invention, in order to make the 0.2% endurance of the aluminum alloy, which is the material of the core tube, 175 N / mm ² or more, the following methods are exemplified. That is: (1) a method of making the aluminum alloy containing components a specific composition; (2) a method of artificial aging hardening to return the extruded aluminum alloy at high temperature to normal temperature, and then increase the temperature again; (3) high temperature Method for quenching (quenching) an extruded aluminum alloy. Among them, from the viewpoint of improving the mechanical properties, the method (1) is preferably a combination of (2) and (3), and the components of the aluminum alloy will be described below. A preferred aspect is: the copper content of the aluminum alloy is 0.15 to 0.5% by weight, preferably 0.1 to 0.4% by weight; the manganese content is 0.04 to 0.8% by weight, preferably 0.05 to 0.5% by weight; the chromium content is 0.01 ～ 0.5% by weight, preferably 0.04 ～ 0.35% by weight; zinc content is 0.01 ～ 0.5% by weight, preferably 0.04 ～ 0.25% by weight. If these components are not contained, the 0.2% endurance tends to decrease, and the core tube's deformation resistance and flex resistance tend to decrease. In addition, when the content of each component is too large, the effect of the present invention tends to be difficult to obtain.

In particular, from the viewpoint of further improving the 0.2% endurance of the above-mentioned aluminum alloy components and further improving the deformation resistance and flex resistance of the core tube, the preferable aspect is: the silicon content is 0.3 to 1.5% by weight, preferably 0.4 to 0.9% by weight. In addition, if the content of this silicon component is too small, the 0.2% endurance tends to decrease as well as the core tube's deformation resistance and flexibility resistance tend to decrease. Therefore, its content should particularly exceed 0.5% by weight.

In addition, from the viewpoint of further improving the 0.2% endurance of the above-mentioned aluminum alloy components and further improving the deformation resistance and flex resistance of the core tube, a preferable aspect is that the iron content is 0.04 to 0.8 weight %, Preferably 0.1 to 0.7% by weight; magnesium content of 0.2 to 1.5% by weight, preferably 0.4 to 1.2% by weight; titanium content of 0.01 to 0.5% by weight, preferably 0.04 to 0.15% by weight.

The size of the core tube varies depending on the width of the rolled polyvinyl alcohol film, but its outer diameter is generally in the range of 150 to 300 mm, preferably in the range of 160 to 260 mm. The length (length in the axial direction) is generally within a range of 2 to 7 m, and preferably within a range of 3 to 6 m. In addition, the wall thickness of the core pipe is generally within a range of 3 to 40 mm, particularly preferably 5 to 30 mm, and further preferably within a range of 6 to 20 mm. In addition, the mass of the core tube is generally within a range of 15 to 500 kg, and particularly preferably within a range of 30 to 150 kg.

In the present invention, the surface of the core tube has a strength of 400 or more in Vickers hardness (HV), and in order to satisfy this physical property, the following methods are cited, for example. That is, (1) a method for forming an anodized film on the surface of the core tube by anodization; (2) a method for electrolytic plating of dissimilar metals such as Cr; (3) a method for coating a hard coating resin, etc. The method (1) is preferable, and the method (1) is described below.

In the present invention, the thickness of the anodized film formed on the surface of the core tube is preferably within a range of 10 to 40 μm. If the thickness is too thin, there is a concern that the aluminum material will be exposed in a short time due to abrasion (inducing a reduction in durability); if it is too thick, the quality will exceed the standard, and the manufacturing cost will increase. In addition, the thickness can generally be measured by a microscope cross-section test method, an electrolytic test method, or a fluorescent X-ray test method, but the microscope cross-section test method is more efficient for convenience.

In addition, from the viewpoint of further preventing damage, the hardness of the anodic oxide film formed on the surface of the core tube is preferably 400 or more in Vickers hardness (HV), particularly 410 to 500, and more preferably 420 to 480.

This anodic oxide film is formed as follows, for example.

That is, first, if necessary, the surface of the core tube is degreased. This degreasing is performed, for example, by immersing the core tube in an acidic aqueous solution such as sulfuric acid or an alkaline aqueous solution containing a surfactant. Then, wash it with water if necessary.

Next, the core tube was immersed in an electrolytic solution, and the core tube was used as an anode to apply a voltage. Thereby, an anodized film is formed on the surface of the core tube. The thickness of the anodic oxide film is adjusted by adjusting the concentration and temperature of the electrolytic solution, the magnitude of the applied voltage and its time, and the like.

Examples of the electrolyte include acidic aqueous solutions such as sulfuric acid, oxalic acid, chromic acid, and phosphoric acid, and these may be used alone or in combination of two or more. The concentration of the electrolytic solution is, for example, within a range of 3% to 20%, and the temperature thereof is, for example, within a range of 0 ° C to 20 ° C. The applied current density is set in a range of, for example, 2 A / dm ² to 10 A / dm ² . Therefore, a cylindrical core tube made of aluminum and having a surface Vickers hardness (HV) of 400 or more was obtained.

On the other hand, the said polyvinyl-alcohol-type film is manufactured as follows, for example. That is, a polyvinyl alcohol-based resin aqueous solution is used to cast a film.

As the polyvinyl alcohol-based resin, an undenatured polyvinyl alcohol-based resin is generally used, that is, a resin produced by saponifying a polyvinyl acetate obtained by polymerizing vinyl acetate. 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. Examples of components that can be copolymerized with vinyl acetate include unsaturated carboxylic acids (including salts, esters, amidines, and nitriles), and olefins having 2 to 30 carbon atoms (ethylene, propylene, n-butene, isobutylene, etc.) , Vinyl ethers, unsaturated sulfonates, etc.

As the polyvinyl alcohol-based resin, a polyvinyl alcohol-based resin having a 1,2-alcohol bond in a side chain can be used. The polyvinyl alcohol-based resin having a 1,2-alcohol bond on the side chain can be obtained, for example, by the following methods: (i) vinyl acetate and 3,4-diethoxyl-1-butane A method for saponification of an olefin copolymer; (ii) a method for saponification and decarboxylation of a copolymer of vinyl acetate and ethylene ethylene carbonate; (iii) a method of saponification of vinyl acetate with 2,2-dialkyl-4-ethylene- A method for saponification and deketalization of a copolymer of 1,3-dioxolane; (iv) A method for saponification of a copolymer of vinyl acetate and glycerol monoallyl ether.

The weight average molecular weight of the polyvinyl alcohol-based resin is preferably 80,000 to 300,000, more preferably 110,000 to 260,000, and still more preferably in the range of 130,000 to 200,000. If the weight-average molecular weight is too small, sufficient optical properties tend not to be obtained when a polyvinyl alcohol-based resin is used as an optical film; if it is too large, it becomes difficult to stretch when the film is used as a polarizing film, and it becomes difficult It is difficult to carry out industrial production. The weight average molecular weight of the polyvinyl alcohol resin is measured by the 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%. As described above, if the average saponification degree is too small, when it is used as a polarizing film, it tends to be difficult to obtain sufficient polarizing performance.

The above polyvinyl alcohol-based resin aqueous solution usually preferably contains glycerin, diglycerol, triglycerol, ethylene glycol, triethylene glycol, polyethylene glycol, and trimethylolpropane, which are generally used plasticizers. The polyvinyl alcohol-based resin is preferably 30% by weight or less, particularly preferably 3 to 25% by weight, and more preferably 5 to 20% by weight. When the said plasticizer is too much, the film strength tends to fall.

Furthermore, it is preferable to include nonionic, anionic, and cationic surfactants, and among them, it is particularly desirable to contain nonionic surfactants such as polyoxyethylene alkylamino ethers. The content of this 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 relative to the polyvinyl alcohol resin. When the said surfactant is too much, there exists a tendency for the external appearance of a film surface to become bad.

The sodium acetate contained in the powder of the polyvinyl alcohol-based resin has an adverse effect on optical performance, and therefore it should be removed (de-vinegarized). The removal (devinegarization) of this sodium acetate is generally performed by adding water to a polyvinyl alcohol-based resin in a devinegarization tank.

Second, the washed polyvinyl alcohol-based resin wet cake is dissolved to prepare a polyvinyl alcohol-based resin aqueous solution. However, if the aqueous polyvinyl alcohol-based resin wet cake is directly dissolved in water, the desired high concentration cannot be obtained. Water solution should be dehydrated first. The method of dehydration is not particularly limited, but is generally a method using centrifugal force. According to a preferred aspect, by the above washing and dehydration, the water-containing polyvinyl alcohol-based resin wet cake with a water content of 50% by weight or less, preferably 30 to 45% by weight, is used. When the water content is too high, it tends to become difficult to become a desired aqueous solution concentration.

Then, in the dissolution tank, the cake-shaped polyvinyl alcohol-based resin was blown with water vapor (approximately 110 to 160 ° C.), and dissolved under pressure to prepare an aqueous polyvinyl alcohol-based resin solution. In this case, a plasticizer or an additive is added as necessary. Thereby, a polyvinyl alcohol-based resin aqueous solution having a water content of about 60 to 80% by weight was obtained.

Then, the obtained polyvinyl alcohol-based resin aqueous solution was filtered to remove impurities, and then degassed. As the degassing treatment method, a degassing treatment method using a stationary degassing or a multi-shaft extruder, etc., is preferably a degassing treatment method using a multi-shaft extruder.

Next, the deaerated polyvinyl alcohol-based resin aqueous solution was filtered again, and then supplied to a T-slot die, extruded from the T-slot die, and diarrhea on the screen.

Thereafter, the polyvinyl alcohol-based resin aqueous solution extruded from the T-slot die is cast, formed, and dried on the outer peripheral surface of the rotating drum roll to form a film. In addition, in order to form the film and dry the drum-type reel, the body is usually at a high temperature (about 80 to 100 ° C.).

Next, the film is peeled from the outer peripheral surface of the drum-type roll, and the surface and the back surface of the film are alternately passed through a plurality of drying rolls (about 60 to 100 ° C), and then a heat treatment machine (100 to About 140 ° C). Then, use a humidifier if necessary. The moisture content of the film is preferably 5% by weight or less, and particularly preferably 1 to 4% by weight. If the water content is too high, the appearance tends to be easily caused when the film is stored. In this way, a polyvinyl alcohol-based film required for the purpose is obtained. The size of the polyvinyl alcohol-based film obtained in this way is generally set to a width in the range of 1.5 to 6 m and a length in the range of 5,000 to 20,000 m.

Thereafter, a core tube made of the specific aluminum material is mounted on a coiler. Next, the winding machine is driven to rotate the core tube, and the obtained polyvinyl alcohol-based film is wound on the outer peripheral surface of the core tube. Here, as the core tube, if a core tube having high strength, excellent deformation resistance and flex resistance is used, when the core tube is rotated by the winding machine, the rotation vibration of the core tube is reduced, The polyvinyl alcohol-based film can be taken up in a homogeneous state without wrinkles. Then, if necessary, the rolled polyvinyl alcohol-based film is cut across the width of the product by a slitter, and then wound again on the core tube. In this manner, the polyvinyl alcohol-based film roll of this embodiment can be obtained. In addition, in the present invention, when the product is stored and transported, it is also suitable to use the core tube as the core tube of the polyvinyl alcohol-based film roll, and there is a case of a step of rewinding after the slitter, In the previous coiling, if it is a core tube with small rotational vibration, high strength, excellent deformation resistance and flex resistance, it does not have to be the core tube, and it can be used appropriately. Core tube or iron core tube.

The polyvinyl alcohol-based film roll thus obtained is moved to a supporting table to support the left and right ends of the core tube. As the core tube, if a core tube having excellent deformation resistance and flex resistance is used as described above, the polyvinyl alcohol film roll formed by winding the polyvinyl alcohol film on the core tube also becomes resistant to deformation. Film rolls with excellent flexibility and flex resistance are supported, stored, or transported in a state where there is no deformation, deflection, or small amount of deformation or deflection.

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. Therefore, 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 mounted on a polarizing film manufacturing apparatus from the support table. Then, the polyvinyl alcohol-based film is taken out from the polyvinyl alcohol-based film roll. At this time, if the polyvinyl alcohol-based film roll is not deformed or deflected as described above, when the polyvinyl alcohol-based film is pulled out, the rotation vibration of the polyvinyl alcohol-based film roll may be reduced, and may be reduced. The polyvinyl alcohol-based film was pulled out in a homogeneous state without wrinkles or cracks. Then, the polyvinyl alcohol-based film was subjected to dyeing, uniaxial stretching, and boride treatment.

The dyeing is performed by contacting the polyvinyl alcohol-based film with a liquid containing iodine or a dichroic dye. In general, when using an iodine-potassium iodide aqueous solution, the concentration of iodine is preferably 0.1 to 20 g / L, the concentration of potassium iodide is 10 to 70 g / L, and the mixed weight ratio of potassium iodide / iodine is in the range of potassium iodide / iodine = 10 to 100. . In addition, the dyeing time is practically about 30 to 500 seconds, and the temperature of the dyeing treatment bath is preferably 5 to 60 ° C. Alternatively, a small amount of an organic solvent compatible with water may be contained in addition to the aqueous solvent. Moreover, as a contact means, arbitrary means, such as dipping, coating, spraying, can be applied.

The above uniaxial extension is preferably an extension of 3 to 10 times, more preferably an extension of 3.5 to 6 times. At this time, it is also possible to perform several extensions at right angles to the uniaxial extension (to prevent the contraction in the width direction or more). The temperature conditions during uniaxial stretching should preferably be set in the range of 40 to 170 ° C. Furthermore, the uniaxial stretching magnification may be finally set to the above-mentioned range. In addition, the uniaxial stretching operation may be performed not only in a single stage, but also in any stage of the manufacturing process.

In addition, the above dyeing can be performed before uniaxial stretching, can be performed simultaneously with uniaxial stretching, or can be performed after uniaxial stretching. However, the polyvinyl alcohol-based film has reduced dyeability due to crystallization due to uniaxial stretching. Therefore, the above dyeing should be performed before or at the same time as uniaxial extension.

The above-mentioned boride treatment is a treatment for strengthening the above-mentioned dyeing. After the above-mentioned dyeing and uniaxial extension, it is performed simultaneously with dyeing or simultaneously with uniaxial extension. As the boride, boric acid and borax are practically used. This boride is used as an aqueous solution or a water-organic solvent mixed solution at a concentration of about 0.3 to 2 mol / L. It is practically suitable to coexist a small amount of potassium iodide in the solution. As a treatment method for the above-mentioned boride, a dipping method is preferable, and a coating method or a spraying method may be performed. In addition, as the processing conditions, the temperature should be about 40 to 70 ° C., and the processing time should be about 2 to 20 minutes. If necessary, it is also suitable to perform an extension operation during processing.

The polarizing film obtained in this way is a polyvinyl alcohol-based film that will be the material of the polarizing film. As described above, if the polyvinyl alcohol-based film roll is extracted in a homogeneous state without wrinkles or cracks, the polarization performance, Excellent appearance characteristics.

Then, an optically isotropic polymer film or sheet may be laminated on one or both sides of the above-mentioned polarizing film as a protective film, laminated and adhered, and used as a polarizing plate. Examples of the protective film include cellulose triacetate, cellulose diacetate, polycarbonate, polymethyl methacrylate, polystyrene, polyether fluorene, polyarylate, and poly-4-methylpentyl. Films or sheets such as olefin, polyphenylene ether, cyclic or norbornene polyolefin. In addition, in order to reduce the thickness, the polarizing film may be replaced with the protective film by hardening resins such as urethane resin, acrylic resin, and urea resin coated on one or both sides, and stacked. .

Furthermore, the above-mentioned polarizing film (or a film having a protective film or a hardening resin laminated on at least one side thereof) also has a transparent pressure-sensitive adhesive layer formed on one surface thereof by a general method as necessary. Actual application situation. Examples of the pressure-sensitive adhesive layer include acrylates such as butyl acrylate, ethyl acrylate, methyl acrylate, and 2-ethylhexyl acrylate, and acrylic acid, maleic acid, itaconic acid, and methacrylic acid. Copolymers containing α-monoolefin carboxylic acids such as crotonic acid (including copolymers containing ethylene monomers such as acrylonitrile, vinyl acetate, and styrene) as the main adhesive layer, which is not particularly harmful to the polarizing performance of polarizing films. suitable. In addition, if it is a pressure-sensitive adhesive having transparency, it can be used. For example, a polyvinyl ether-based or rubber-based adhesive can also be used.

The polarizing film thus obtained can be used, for example, in liquid crystal display devices such as liquid crystal displays (electronic desktop computers, electronic clocks, word processors, personal computers, portable information terminals, automobile or mechanical gauges). ), Sunglasses, anti-glare glasses, 3D glasses, display elements (CRT, LCD, etc.), anti-reflection layers, medical equipment, building materials, toys, etc. [Example]

Hereinafter, the present invention will be described more specifically by exemplifying examples, but the present invention is not limited to the following examples as long as the scope of the present invention is not exceeded. In addition, "part" and "%" in the examples refer to weight basis.

[Example 1] After the core tube and the polyvinyl alcohol-based film were produced as described below, a polyvinyl alcohol-based film was wound around the outer peripheral surface of the core tube to produce a polyvinyl alcohol-based film roll. Next, a polarizing film was produced using the polyvinyl alcohol film of the polyvinyl alcohol film roll.

[Core tube] A cylindrical core tube was produced using aluminum alloy A6N01 specified by JIS as a material. The chemical composition of the aluminum alloy A6N01 is shown in Table 1 below. The dimensions of the core tube are: outer diameter 215mm, cylinder length 3500mm, wall thickness 6mm.

[Anodic Oxidation Film] The core tube was subjected to anodization to form an anodized film with a thickness of 20 μm on the surface of the core tube. The Vickers hardness (HV) of the surface of the obtained core tube was 410.

[Polyvinyl alcohol-based film] Polyoxyethylene alkylamino ether as a surfactant (release agent) is used 100 parts of polyvinyl alcohol with a weight average molecular weight of 135,000 and a saponification degree of 99.7 mol%, 12 parts of glycerin as a plasticizer, and a surfactant. 0.1 parts, and a 35% strength polyvinyl alcohol aqueous solution (a plasticizer and a release agent are also included as a solid component) is prepared, and then the film is cast from a T-slot die by a roll reel, and dried and heat-treated. With humidity adjustment, a polyvinyl alcohol film with a moisture content of 4%, a width of 3000 mm, and a thickness of 75 μm was produced.

[Production of the polyvinyl alcohol-based film roll] Then, the polyvinyl alcohol-based film was wound up to 10,000 m on the outer peripheral surface of the core tube. At this time, the winding tension (tensile force per width of the polyvinyl alcohol-based film of 1 m) was set to 130 N / m, and the winding speed was set to 80 m / min. The mass of the rolled polyvinyl alcohol film roll was 3009kg.

[Production of polarizing film] After that, the rolled polyvinyl alcohol-based film was drawn out at a speed of 1.23 m / min, and swollen in a water-washing tank (24 ° C), and then in an iodine tank (20 ° C, iodine 0.17g / L) A uniaxial extension of 1.8 times is performed. A uniaxial extension of 2.0 times is performed in a boric acid tank (50 ° C, 8 ppm iodine, 47 g / L boric acid), and a uniaxial extension of 5.2 times is performed at a winding speed of 6.4 m / min To make a polarizing film.

[Example 2] A cylindrical core tube was produced using aluminum alloy A6061 specified by JIS as a material. The chemical composition of the aluminum alloy A6061 is shown in Table 1 below. The core tube has the dimensions of 233 mm in outer diameter, 4800 mm in cylinder length and 15 mm in wall thickness. The anodized film, the polyvinyl alcohol-based film, and the polyvinyl alcohol-based film roll are the same as those in the first embodiment. The Vickers hardness (HV) of the surface of the obtained core tube was 420.

[Example 3] A cylindrical core tube was produced using aluminum alloy A6063 specified by JIS as a material. The chemical composition of this aluminum alloy A6063 is shown in Table 1 below. The dimensions of the core tube, the anodized film, the polyvinyl alcohol-based film, and the polyvinyl alcohol-based film roll are the same as those in the first embodiment. The Vickers hardness (HV) of the surface of the obtained core tube was 405.

[Comparative Example] In the above-mentioned Example 3, an anodized film was not formed on the surface of the core tube, and the same polyvinyl alcohol-based film as in the above-mentioned Example 3 was wound on the outer peripheral surface thereof to produce a polyvinyl alcohol-based film roll. Other than that, it is the same as the third embodiment. The Vickers hardness (HV) of the surface of the core tube used was 150.

[Presence or absence of damage to the core tube] In the core tubes used in the above Examples 1 to 3 and Comparative Examples, a cutter (Utility Knife) was used, parallel to the width direction of the core tube, to overlap five A4 photocopying papers. The cutting force is used for cutting operation. As a result, those with no damage were evaluated as ◎ for excellent damage prevention, those with only small damage were rated as ○ for good damage prevention, and those with large damage were rated as poor damage prevention. This was evaluated as × and recorded in Table 2 below.

[Presence or absence of damage to the polyvinyl alcohol-based film] Next, the polyvinyl alcohol-based film was wound around the core tube used in the above-mentioned Examples 1 to 3 and Comparative Examples which had been subjected to a cutting operation. In addition, in order to fix the polyvinyl alcohol-based film to the core tube, a product named CUTACE MS (50 mm × 50 m) manufactured by Sumitomo Plastic Co., Ltd. was used as the adhesive tape. All the polyvinyl alcohol-based films were taken out from the polyvinyl alcohol-based film rolls of Examples 1 to 3 and Comparative Examples that were left for one day, and the presence or absence of damage to the polyvinyl alcohol-based films was evaluated by naked eyes. As a result, the non-injured person was evaluated as being excellent in homogeneity, the small-injured person was evaluated as excellent in homogeneity, and the large-injured person was evaluated as inferior in homogeneity. It was evaluated as x and recorded in Table 2 below.

[Presence of Residual Adhesive Tape] After removing all polyvinyl alcohol-based films from the polyvinyl alcohol-based film rolls of Examples 1 to 3 and Comparative Examples above, the adhesive tape remaining on the core tube was peeled off. Evaluate the presence or absence. As a result, those who did not have glue residues were evaluated as being excellent in homogeneity, those with only slight residues were evaluated as excellent in homogeneity, and those with a large amount of residues were evaluated as being poor in homogeneity. This was evaluated as × and recorded in Table 2 below.

From the results in Table 2 above, in Examples 1 to 3 in which an anodized film was formed on the surface of the core tube and the Vickers hardness (HV) of the surface of the core tube was 400 or more, the surface of the core tube was not damaged or was not easily generated. In the comparative example in which the anodized film was not formed and the Vickers hardness (HV) of the surface of the core tube was 150, the surface of the core tube was prone to damage. From this result, it is known that the Vickers hardness (HV) of the surface of the core tube is high, and damage can be prevented. In addition, it is presumed that the difference between the damages of Examples 1 and 2 and Example 3 is because the hardness of the aluminum alloy of the core tube material of Examples 1 and 2 is higher than that of Example 3.

And there is no damage on the surface of the core tube, or even if there is damage, the polyvinyl alcohol film is not damaged, or even if there is damage, it is still slight. In the case of using it as a polarizing film, a homogeneous film can still be obtained. On the other hand, when there is damage on the surface of the core tube, damage also occurs in the polyvinyl alcohol-based film, and when it is used as a polarizing film, a homogeneous film cannot be obtained. From this result, it is known that in the polyvinyl alcohol film roll, the formation of the anodized film on the surface of the core tube is very important.

Although the specific embodiment of the present invention is shown in the above embodiment, the above embodiment is merely an example, and is not to be construed as a limitation. It is conceivable that various modifications known to those skilled in the art belong to the scope of the present invention. [Industrial availability]

The present invention can be used in the case of preventing damage to the surface of the core tube, obtaining a non-damaging polyvinyl alcohol-based film, and a non-damaging polarizing film.

no

no

Claims (5)

A polyvinyl alcohol-based film roll is formed by winding a polyvinyl alcohol-based film for optics into a cylindrical core tube, which is characterized in that the core tube is made of aluminum and the surface of the core tube is The hardness (HV) is 400 or more, the outer diameter of the core tube is 150 to 300 mm, and the cylinder length of the core tube is 2 to 7 m. For example, the polyvinyl alcohol-based film roll of item 1 of the patent application scope, wherein an anodized film is formed on the surface of the core tube by anodization. For example, the polyvinyl alcohol-based film roll of item 1 or 2 of the patent application scope, wherein the aluminum material is an aluminum alloy. For example, the polyvinyl alcohol-based film roll of item 2 of the patent application scope, wherein the thickness of the anodized film formed on the surface of the core tube is 10 to 40 μm. A polarizing film, which is obtained by using a polyvinyl alcohol-based film extracted from a polyvinyl alcohol-based film roll according to any one of claims 1 to 4.