TW201508020A - Polyvinyl alcohol film roll and polarizing film using same - Google Patents

Abstract

Provided is a polyvinyl alcohol film roll which delivers a film of a uniform quality and is capable of providing a polarizing film that has excellent polarization performance and appearance characteristics, and wherein the surface of a core tube can be prevented from being damaged. This polyvinyl alcohol film roll is obtained by winding a polyvinyl alcohol film for optical applications around a cylindrical core tube. The core tube is formed of an aluminum material, and the surface of the core tube has a Vickers hardness (HV) of 400 or more.

Description

Polyvinyl alcohol film roll and polarizing film using the film roll

The present invention relates to a polyvinyl alcohol film roll, and more particularly to a polyvinyl alcohol film roll having a wide and elongated strip of polyvinyl alcohol film, and the use of the film A polarizing film excellent in polarizing performance obtained by reeling.

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

In general, a polyvinyl alcohol-based film is wound up in a cylindrical core tube after film formation, whereby it is commercialized.

In recent years, in order to increase the size of the liquid crystal display device, it is required to increase the size of the polyvinyl alcohol-based film, in particular, to increase the width of the liquid crystal display device, and further, when a polarizing film is produced using a polyvinyl alcohol-based film, from the viewpoint of productivity. Look, it requires a strip of more than 5000m.

As a core tube of a polyvinyl alcohol-based film which is elongated in a wide strip shape, it is preferable to use a core tube of aluminum from the viewpoint of weight, strength, cost, etc. of the core tube (refer to, for example, Patent Document 1) And 2). [Practical Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2004-106377 (Patent Document 2): JP-A-2001-315885

[Problems to be solved by the present invention]

On the other hand, when the polyvinyl alcohol-based film is taken up or taken out, the surface shape of the core tube affects the appearance of the film of the polyvinyl alcohol-based film and the polarizing performance as a polarizing film. Further, in the case where the core tube is stored or transported in a state in which only the core tube is left with the polyvinyl alcohol-based film, there is a possibility that the core tube is not damaged and a good surface shape is maintained. In addition, in the case where the polyvinyl alcohol-based film is not used, there is a case where the cutting blade is cut in parallel with the width direction of the film and is peeled off from the core tube, but at this time, there is still contact cutting. The knife still does not damage the core tube, and the necessity of maintaining a good surface shape.

On the other hand, the polyvinyl alcohol-based film is a hydrophilic film, and is more susceptible to moisture than other hydrophobic films, and is easily affected by external factors. Therefore, it is easily affected by the surface shape of the core tube. Transfer to film. Therefore, it is necessary to review the core tube which is most suitable for the polyvinyl alcohol film.

Under such circumstances, an object of the present invention is to provide a polyvinyl alcohol-based film roll which can obtain a polarizing film having excellent polarizing performance and appearance characteristics, which can prevent damage of 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 invention repeatedly conducted intensive studies in order to achieve this object, and as a result, found the following, and completed the present invention: considering the material of the core tube is aluminum, by making the surface of the core tube Vickers hardness (HV) 400 or more, and effectively preventing the damage of the surface of the core tube, and also improving the corrosion resistance, and extracting the polyvinyl alcohol-based film roll formed by winding the polyvinyl alcohol-based film onto the core tube The film is a film which is homogeneous without damage, and the polarizing film produced by the film is a polarizing film excellent in polarizing performance and appearance characteristics.

In the first aspect of the invention, a polyvinyl alcohol film roll is obtained by winding an optical polyvinyl alcohol film on a cylindrical core tube, the core tube being made of an aluminum material, and the core The surface of the tube has a Vickers hardness (HV) of 400 or more. The second aspect 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 by a cutting blade or the like and peeled off, the cutting core or the like is contacted. Further, when only the core tube is stored or transported, the damage of the surface of the core tube can be effectively prevented, and the weather resistance is also excellent. As a result, in the polyvinyl alcohol-based film roll of the present invention, the extracted film can be a non-damaged homogeneous film, and the polarizing film produced by the film can be a polarizing film excellent in polarizing performance and appearance characteristics.

In particular, when the surface of the core tube is anodized to form an anodized film, the hardness and strength of the core tube are increased to prevent damage to the surface of the core tube.

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

Further, in the case where 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.

Further, the polarizing film of the present invention is a polarizing film which is excellent in polarizing performance and appearance characteristics by using a non-damaged homogeneous film which is extracted from the polyvinyl alcohol-based film roll of the present invention.

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

An embodiment of the polyvinyl alcohol-based film roll of the present invention comprises the following elements: a cylindrical core tube made of an aluminum material, and having a Vickers hardness (HV) of 400 or more on the surface of the core tube; and polyethylene The alcohol-based film is taken up on the outer peripheral surface of the core tube. In this manner, the surface of the core tube is prevented from being damaged by the Vickers hardness (HV) of the core tube surface of 400 or more, and the polyvinyl alcohol-based film wound around the outer peripheral surface of the core tube is transferred without damage. Ground, become a homogeneous film.

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

The aluminum alloy is excellent in deformation resistance and flex resistance, and can be made to have a 0.2% proof stress of 175 N/mm from the viewpoint of the widening of the polyvinyl alcohol-based film (the width of the core tube). ² or more, particularly preferably 175 to 600 N/mm ² , further preferably 200 to 400 N/mm ² .

In the present invention, in order to make the 0.2% proof stress of the aluminum alloy which is the material of the above-mentioned core tube 175 N/mm ² or more, the following methods are mentioned, for example. That is, (1) a method of making the composition of the aluminum alloy into a specific composition; (2) a method of artificially hardening the aluminum alloy after the high temperature extruded aluminum alloy is returned to the normal temperature, and then the temperature is raised again; A method of quenching (quenching) an extruded aluminum alloy. Among them, from the viewpoint of improving the mechanical properties, it is preferable to combine the methods (2) and (3) of the above method (1), and the components of the aluminum alloy will be described below. Preferably, the aluminum alloy has a copper content of 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; and the chromium content is 0.01. ～0.5% by weight, preferably 0.04 to 0.35% by weight; and the zinc content is 0.01 to 0.5% by weight, preferably 0.04 to 0.25% by weight. If these components are not contained, the above-mentioned 0.2% resistance tends to decrease, and the deformation resistance and flex resistance of the core tube tend to decrease. Further, too much content of each component tends to make it difficult to obtain the effects of the present invention.

In particular, in the composition of the aluminum alloy, from the viewpoint of further improving the above-mentioned 0.2% proof stress and further improving the deformation resistance and the flex resistance of the core tube, the preferred aspect is that the amount of niobium is 0.3 to 0.3%. 1.5% by weight, preferably 0.4 to 0.9% by weight. Further, when the content is too small, the above-mentioned 0.2% resistance tends to decrease, and the deformation resistance and flex resistance of the core tube tend to be lowered. Therefore, the content is particularly preferably more than 0.5% by weight.

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

The size of the above-mentioned core tube varies depending on the width of the polyvinyl alcohol-based film to be taken up, and the outer diameter thereof is generally in the range of 150 to 300 mm, preferably in the range of 160 to 260 mm, and the cylinder. The length (length in the axial direction) is generally in the range of 2 to 7 m, preferably in the range of 3 to 6 m. Further, the wall thickness of the core tube is generally preferably in the range of 3 to 40 mm, particularly preferably 5 to 30 mm, and more preferably 6 to 20 mm. Further, the mass of the above-mentioned core tube is generally in the range of 15 to 500 kg, particularly preferably in the range of 30 to 150 kg.

In the present invention, the surface of the core tube has a Vickers hardness (HV) of 400 or more, and in order to satisfy the physical properties, for example, the following methods are exemplified. That is, there are: (1) a method of forming an anodized film by anodization on a surface of a core tube; (2) a method of electrolytically plating a dissimilar metal such as Cr; (3) a method of applying a hard-coating resin or the like, wherein The method of the above (1) is preferred, and the method of the above (1) will be described below.

In the present invention, it is preferred that the anodized film formed on the surface of the core tube has a thickness in the range of 10 to 40 μm. If the thickness is too small, there is a fear that the aluminum material is exposed in a short time due to abrasion (resulting in a decrease in durability); if it is too thick, the quality is exceeded and the manufacturing cost is increased. In addition, the thickness can be generally determined by a microscope cross-section test method, an electrolytic test method, a fluorescent X-ray test method, etc., but the microscope cross-section test method is more convenient for convenience.

Further, from the viewpoint of further preventing damage, the hardness of the anodized film formed on the surface of the core tube is preferably a Vickers hardness (HV) of 400 or more, particularly preferably 410 to 500, more preferably 420 to 480.

The anodized film is formed, for example, as follows.

That is, first, the surface of the core tube is degreased as necessary. This degreasing is carried out, for example, by an acidic aqueous solution such as sulfuric acid or an alkaline aqueous solution containing a surfactant, by immersing the above-mentioned core tube. Then, wash it as necessary.

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

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

On the other hand, the above polyvinyl alcohol-based film is produced, for example, as follows. That is, the film is formed by casting using a polyvinyl alcohol-based resin aqueous solution.

As the polyvinyl alcohol-based resin, an undenatured polyvinyl alcohol-based resin, that is, a resin obtained by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, is generally 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) copolymerizable with vinyl acetate may be used. Examples of the component copolymerizable with vinyl acetate include an unsaturated carboxylic acid (including a salt, an ester, a guanamine, a nitrile, etc.) and an olefin having 2 to 30 carbon atoms (ethylene, propylene, n-butene, isobutylene, etc.). , vinyl ethers, unsaturated sulfonates, and the like.

Further, as the polyvinyl alcohol-based resin, a polyvinyl alcohol-based resin having a 1,2-alcohol bond in its side chain can be used. The polyvinyl alcohol-based resin having a 1,2-alcohol bond in the one side chain can be obtained, for example, by the following methods: (i) vinyl acetate and 3,4-diethyloxy-1-butane a method for saponifying a copolymer of an alkene; (ii) a method for saponifying and decarboxylating a copolymer of vinyl acetate and ethylene carbonate; (iii) a vinyl acetate with 2,2-dialkyl-4-ethylene- a method of saponification and deketalization of a copolymer of 1,3-dioxolane; (iv) a method of saponifying a copolymer of vinyl acetate and glycerol monoallyl ether.

The weight average molecular weight of the polyvinyl alcohol-based resin is preferably from 80,000 to 300,000, more preferably from 110,000 to 260,000, still more preferably from 130,000 to 200,000. When the weight average molecular weight is too small, when the polyvinyl alcohol-based resin is used as an optical film, sufficient optical performance tends not to be obtained. When the film is too large, stretching becomes difficult when the film is used as a polarizing film. It is difficult to carry out industrial production. Further, the weight average molecular weight of the polyvinyl alcohol-based 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%, particularly preferably 98 to 100 mol%. As described above, when the average degree of saponification is too small, it is difficult to obtain sufficient polarizing performance when it is used as a polarizing film.

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

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

The sodium acetate contained in the powder of the polyvinyl alcohol-based resin adversely affects the optical properties, so it is preferable to remove it (de-vinegar). The removal (de-vinegar) of the sodium monoacetate is generally carried out by adding water to the polyvinyl alcohol-based resin in a vinegar tank.

Next, the washed aqueous polyvinyl alcohol-based resin wet cake is dissolved to prepare a polyvinyl alcohol-based resin aqueous solution, and the desired high concentration cannot be obtained by directly dissolving the aqueous polyvinyl alcohol-based resin wet cake in water. The aqueous solution should be dehydrated first. The dehydration method is not particularly limited, but is generally a method using centrifugal force. In a preferred embodiment, the aqueous polyvinyl alcohol-based resin wet cake having a water content of 50% by weight or less, preferably 30 to 45% by weight, is prepared by the above-mentioned washing and dehydration. If the water content is too high, there is a tendency that it becomes difficult to become a desired aqueous solution concentration.

Then, in the dissolution tank, water vapor (about 110 to 160 ° C) is blown into the cake-shaped polyvinyl alcohol-based resin, and the mixture is pressurized and dissolved to prepare a polyvinyl alcohol-based resin aqueous solution. At this time, 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 is 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 or the like produced by using a static degassing or a multiaxial extruder is preferably a degassing treatment method using a multiaxial extruder.

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

Thereafter, the polyvinyl alcohol-based resin aqueous solution which is 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. Further, in order to form and dry the above film, the drum type drum usually has a high temperature (about 80 to 100 ° C).

Next, the film is peeled off from the outer peripheral surface of the drum reel so that the surface and the back surface of the film are passed through a plurality of drying rolls (about 60 to 100 ° C), and a heat treatment machine (100 ~) is preferably used. 140 ° C degree). Then, use the humidity regulator as necessary. The moisture content of the film is preferably 5% by weight or less, particularly preferably from 1 to 4% by weight. When the water content is too high, there is a tendency that the appearance is poor when the film is stored. Thus, a polyvinyl alcohol-based film required for the purpose was obtained. The size of the obtained polyvinyl alcohol-based film is generally set to a width of 1.5 to 6 m and a length of 5,000 to 20,000 m.

Thereafter, a core tube composed of the specific aluminum material is attached to a coiler. Next, the coiler was driven to rotate the core tube, and the obtained polyvinyl alcohol-based film was wound up on the outer peripheral surface of the core tube. Here, when the core tube having high strength, excellent deformation resistance, and flex resistance is used as the core tube, when the core tube is rotated by the coiler, the rotational vibration of the core tube becomes small. The polyvinyl alcohol-based film can be taken up in a homogeneous state such as wrinkle-free. Then, if necessary, the coiled polyvinyl alcohol film was cut by the slitter at the product width width, and was again taken up in the core tube. Thus, the polyvinyl alcohol-based film roll of the present embodiment can be obtained. Further, in the present invention, in the state of being stored and transported as a product, it is preferable to use the core tube as a core tube of a polyvinyl alcohol-based film roll, and to have a step of rewinding after the slitter, In the conventional coiling, if the core tube having high strength, high deformation resistance, and high flex resistance is used, it is not necessary to use the above-mentioned core tube, and it is possible to appropriately use the aluminum tube different from the above. Core tube or iron core tube, etc.

The polyvinyl alcohol-based film roll thus obtained is moved to the support table to support the left and right end portions of the core tube. When a core tube excellent in deformation resistance and flex resistance as described above is used as the core tube, the polyvinyl alcohol-based film roll formed by winding the polyvinyl alcohol-based film on the core tube is also resistant to deformation. The film reel with excellent flexibility and flexibility is supported, stored or transported in a state free from deformation, deflection, or deformation and deflection.

Further, the polyvinyl alcohol-based film of the polyvinyl alcohol-based film roll is very useful as an optical film, particularly a material for forming 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 film roll is attached to the polarizing film manufacturing apparatus from the above-mentioned support stand. Then, the polyvinyl alcohol-based film was taken out from the polyvinyl alcohol-based film roll. In this case, when the polyvinyl alcohol-based film roll is not deformed or deflected as described above, when the polyvinyl alcohol-based film is taken out, the rotational vibration of the polyvinyl alcohol-based film roll becomes small. The polyvinyl alcohol-based film is taken out in a homogeneous state such as no wrinkles or breakage. Then, the polyvinyl alcohol-based film was subjected to dyeing, uniaxial stretching, and boride treatment.

The dyeing is carried out by bringing the polyvinyl alcohol-based film into contact with a liquid containing iodine or a dichroic dye. In general, using an aqueous solution of iodine-potassium iodide, 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 weight ratio of potassium iodide to iodine is potassium iodide/iodine = 10 to 100. . Further, the dyeing time is practically about 30 to 500 seconds, and the temperature of the dyeing treatment bath is preferably 5 to 60 °C. In addition to the aqueous solvent, a small amount of an organic solvent compatible with water may be used. Further, as the contact means, any means such as dipping, coating, spraying, or the like can be applied.

The above uniaxial extension is preferably extended to 3 to 10 times, more preferably 3.5 to 6 times. At this time, it is also possible to perform a plurality of extensions in the direction perpendicular to the uniaxial extension (prevention of the extent of the contraction in the width direction or the extension thereof). The temperature condition at the time of uniaxial stretching should be set to a range of 40 to 170 °C. Further, the uniaxial stretching ratio may be finally set to the above range, and the uniaxial stretching operation may be carried out not only in a single stage but also in any stage of the process.

Further, the dyeing may be carried out before the uniaxial stretching, and may be carried out simultaneously with the uniaxial stretching or after the uniaxial stretching, but the polyvinyl alcohol-based film is deteriorated in dyeability due to crystallization by uniaxial stretching. Therefore, the above dyeing should be carried out before or at the same time as the uniaxial stretching.

The boride treatment is used for the treatment of strengthening the dyeing, after the dyeing and uniaxial stretching, or simultaneously with dyeing or simultaneously with uniaxial stretching. As the above boride, boric acid and borax are actually used. The monoboride is used as an aqueous solution or a water-organic solvent mixture at a concentration of 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 for the above-described boride, it is preferably a dipping method, and a coating method or a spraying method may be applied. Further, as the processing conditions, it is preferred to have a temperature of about 40 to 70 ° C and a treatment time of 2 to 20 minutes, and it is also necessary to carry out the stretching operation during the treatment as necessary.

The polarizing film obtained in this manner is a polyvinyl alcohol-based film which is a material of the polarizing film, and as described above, the polyvinyl alcohol-based film roll is taken out in a homogeneous state such as wrinkle-free or rupture, and the polarizing performance is Excellent appearance.

Then, an optically isotropic polymer film or sheet may be laminated and adhered as a protective film on one surface or both sides of the polarizing film, and used as a polarizing plate. Examples of the protective film include cellulose triacetate, cellulose diacetate, polycarbonate, polymethyl methacrylate, polystyrene, polyether oxime, polyaryl aryl ester, and poly-4-methyl pentane. A film or sheet of a polyolefin such as an alkene, a polyphenylene ether, a ring system or a norbornene-based polyolefin. In addition, in order to reduce the thickness, the protective film may be replaced with a curable resin such as a urethane resin, an acrylic resin or a urea resin on one or both sides of the polarizing film, and stacked. .

Further, the polarizing film (or a film having a protective film or a curable resin laminated on at least one side thereof) may have a transparent pressure-sensitive adhesive layer formed by a general method on one surface thereof. The actual application situation. As the pressure-sensitive adhesive layer, for example, an acrylate such as butyl acrylate, ethyl acrylate, methyl acrylate or 2-ethylhexyl acrylate, and acrylic acid, maleic acid, itaconic acid, or methacrylic acid are used. An adhesive layer mainly composed of a copolymer of an α-monoolefin carboxylic acid such as crotonic acid (a copolymer containing an ethylene monomer such as acrylonitrile, vinyl acetate or styrene), which does not hinder the polarizing property of the polarizing film. suitable. In addition, it can be used as a pressure-sensitive adhesive having transparency, and for example, a polyvinyl ether type or a rubber type can also be used.

The polarizing film thus obtained can be used, for example, in a liquid crystal display device such as a liquid crystal display (electronic desktop computer, electronic timepiece, word processor, personal computer, portable information terminal, automobile, or mechanical type). ), sunglasses, anti-glare glasses, 3D glasses, display elements (CRT, LCD, etc.) for reducing reflective layers, medical equipment, building materials, toys, etc. [Examples]

In the following, the present invention will be more specifically described by the examples, and the present invention is not limited by the following examples without departing from the scope of the invention. In addition, the "parts" and "%" in the examples refer to the weight basis.

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

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

[Anodic Oxide Film] The above-mentioned core tube was anodized to form an anodized film having 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] 100 parts of polyvinyl alcohol having a weight average molecular weight of 135,000 and a degree of saponification of 99.7 mol%, 12 parts of glycerin as a plasticizer, and a polyoxyethylene alkylamino ether as a surfactant (release agent) 0.1 part, and a 35% aqueous solution of polyvinyl alcohol (plasticizer, release agent is also included as a solid component) is prepared, and then a film is cast from a T-slot die by a drum type roll, and drying and heat treatment are performed. A polyvinyl alcohol-based film having a water content of 4%, a width of 3000 mm, and a thickness of 75 μm was produced by adjusting the humidity.

[Preparation of a polyvinyl alcohol-based film roll] Then, the polyvinyl alcohol-based film 10000 m was wound up on the outer peripheral surface of the above-mentioned core tube. At this time, the winding tension (the tensile force per width of 1 m of the polyvinyl alcohol-based film) was 130 N/m, and the winding speed was 80 m/min. The quality of the wound polyvinyl alcohol film roll was 3009 kg.

[Preparation of polarizing film] After that, the wound polyvinyl alcohol film was taken out at a rate of 1.23 m/min, and swelled in a water washing tank (24 ° C), and then in an iodine tank (20 ° C, iodine 0.17 g / L) A 1.8-fold uniaxial extension was performed, and a uniaxial extension of 2.0 times was carried out in a boric acid tank (50 ° C, iodine 8 ppm, boric acid 47 g/L), and a 5.2-fold uniaxial extension was further performed at a take-up speed of 6.4 m/min. , and made a polarizing film.

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

[Example 3] A cylindrical core tube was produced by using aluminum alloy A6063 defined by JIS as a material. The chemical composition of the aluminum alloy A6063 is shown in Table 1 below. The size of the core tube, the anodized film, the polyvinyl alcohol film, and the polyvinyl alcohol film roll were the same as in the above-described first embodiment. Further, the surface of the obtained core tube had a Vickers hardness (HV) of 405.

[Comparative Example] In the above-mentioned Example 3, an anodized film was not formed on the surface of the core tube, and a polyvinyl alcohol-based film similar to that of the above-mentioned Example 3 was wound around the outer peripheral surface thereof to prepare a polyvinyl alcohol-based film roll. Other than this, it is the same as Embodiment 3 described above. Further, the core tube surface used had a Vickers hardness (HV) of 150.

[The presence or absence of the damage of the core tube] The core tube used in the above Examples 1 to 3 and the comparative example was superposed with five sheets of A4 copy paper in parallel with the width direction of the core tube using a utility knife. The cutting force is used to perform the cutting operation. As a result, the damage-free person is evaluated as ◎, and the damage-impairing property is excellent, and it is evaluated as ○, and the large-damaged person is poor in damage prevention. This was evaluated as × and recorded in Table 2 below.

[Presence or absence of damage of the polyvinyl alcohol-based film] Next, the polyvinyl alcohol-based film was taken up by the core tube used in the above Examples 1 to 3 and the comparative example subjected to the cut operation. Further, in order to fix the polyvinyl alcohol-based film to the core tube, a product named CUTACE MS (50 mm × 50 m) manufactured by Susei Plastics Co., Ltd. was used as the tape. The polyvinyl alcohol-based film of the above-mentioned Examples 1 to 3 and the comparative examples were taken out from the first day, and the polyvinyl alcohol-based film was taken out, and the presence or absence of damage of the polyvinyl alcohol-based film was visually observed. As a result, the non-damaged person was evaluated as ◎ in order to be excellent in homogeneity, and it was evaluated as ○ in the case of only small damage, and was evaluated as ○ in the case of small damage, and the homogenity was poor in the case of large damage. The evaluation was × and recorded in Table 2 below.

[The presence or absence of the adhesive residue of the tape] The tape remaining in the core tube after the entire polyvinyl alcohol-based film was taken out from the polyvinyl alcohol-based film rolls of the above Examples 1 to 3 and the comparative example, and the residual rubber was observed by the naked eye. Evaluate whether or not there is. As a result, the residue-free one was evaluated as ◎, and only some of the micro-residues were excellent in homogeneity and evaluated as ○, and those having a large amount of residual glue were poor in homogeneity. This was evaluated as × and recorded in Table 2 below.

From the results of the above Table 2, in the examples 1 to 3 in which the anodic oxide 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 anodic oxide 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 liable to be damaged. From this result, it is known that the Vickers hardness (HV) of the surface of the core tube is high to prevent damage. Further, the difference in the damage of Examples 1, 2 and 3 was presumed to be higher than that of Example 3 because of the hardness of the aluminum alloy of the core tube material of Examples 1 and 2.

However, the surface of the core tube is not damaged, or even if the damage is still slight, the polyvinyl alcohol film is not damaged, or even if it is damaged, it is still mild, and a homogeneous film can be obtained as a polarizing film. On the other hand, in the case where the surface of the core tube is damaged, the polyvinyl alcohol-based film is also damaged, and a homogeneous film cannot be obtained as a polarizing film. From this result, it was found that the formation of an anodized film on the surface of the core tube was important in the polyvinyl alcohol film roll.

In the above embodiments, the specific embodiments of the present invention are shown, but the above embodiments are merely illustrative and not intended to be limiting. Various modifications apparent to those skilled in the art are intended to be within the scope of the invention. [Industrial use]

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

no

no

Claims (6)

A polyvinyl alcohol-based film roll comprising a polyvinyl alcohol-based film for optical winding in a cylindrical core tube, wherein the core tube is made of an aluminum material, and the surface of the core tube is Vickers. Hardness (HV) of 400 or more. A polyvinyl alcohol-based film roll according to the first aspect of the invention, wherein an anodized film is formed on the surface of the core tube by anodization. The polyvinyl alcohol-based film reel according to claim 1 or 2, wherein the aluminum material is an aluminum alloy. The polyvinyl alcohol-based film roll according to claim 2, wherein the anodized film formed on the surface of the core tube has a thickness of 10 to 40 μm. The polyvinyl alcohol-based film reel according to claim 1 or 2, wherein 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. A polarizing film obtained by using a polyvinyl alcohol-based film obtained by a polyvinyl alcohol-based film roll according to any one of claims 1 to 5.