JP4195017B2 - Polyvinyl alcohol film roll - Google Patents

Description

The present invention relates to a polyvinyl alcohol film roll formed by winding a polyvinyl alcohol film in a cylindrical core tube.

  A polarizing film is used for a liquid crystal display or the like, and a polyvinyl alcohol film that is dyed and uniaxially stretched is often used for the polarizing film. And the polyvinyl alcohol-type film is generally manufactured as follows. That is, after dissolving a polyvinyl alcohol-type resin in a solvent and defoaming to prepare a stock solution, an aqueous polyvinyl alcohol-type resin solution is extruded from the T-type slit die onto the outer peripheral surface of the drum-type roll. And it is manufactured by casting, forming a film on the outer peripheral surface of the drum-type roll, and drying it. Then, it peels from the said drum type roll, passes through processes, such as heat processing, and is wound up by the core pipe, and forms a polyvinyl-alcohol-type film roll.

  And when manufacturing the said polarizing film, a polyvinyl alcohol-type film is drawn out from the said roll, and dyeing | staining and uniaxial stretching are performed. Since the polarizing film produced in this way is used for a liquid crystal display or the like, a film excellent in uniformity in optical performance such as polarization is required.

  In order to meet the demand, it is required to prevent defects such as wrinkles and folds in the polyvinyl alcohol film during winding and unwinding of the polyvinyl alcohol film and storage or transportation of the roll. It is done. This is because when such a problem occurs, the polarization property becomes uneven, and the optical performance is not uniform.

Therefore, the present applicant has proposed a roll that prevents the above-described wrinkles and breakage (see Patent Document 1). This roll is a roll made of a metal material and having a surface roughness of 100S or less as a core tube. Thereby, the wrinkles and breakage of a polyvinyl alcohol-type film are prevented.
JP 2004-106377 A

  Recently, however, the demand for a wide variety of polyvinyl alcohol-based films has increased, and correspondingly, a long core tube is used. For this reason, a core pipe is easy to bend and generation | occurrence | production of the wrinkle of a polyvinyl alcohol-type film, a breakage, etc. has been a problem. In addition, the core tube becomes heavy, and its handling property is also a problem. From these problems, the roll of Patent Document 1 in which the core tube is made of a metal material still has room for improvement.

The present invention has been made in view of such circumstances, and even when the core tube is elongated, the polyvinyl alcohol is excellent in handleability and can suppress wrinkles and breakage of the polyvinyl alcohol film. providing system film roll and an object.

In order to achieve the above object, the present invention provides a polyvinyl alcohol film roll obtained by winding a polyvinyl alcohol film on an outer peripheral surface of a cylindrical core tube, and the core tube is made of carbon fiber reinforced plastic. The first gist is a polyvinyl alcohol film roll having an elastic modulus (E ₁ ) of the core pipe calculated by using the following formula (1) of 98 GPa or more.

here,
L: Length of core tube (mm) [L = L ₁ × 2 + L ₂ ]
L ₁ : Length from the end face of the core tube to the end face of the film (mm)
L ₂ : Polyvinyl alcohol film width (mm)
W ₁ : Uniformly distributed load of core tube (N / mm)
W ₂ : Uniform load of core tube + film (N / mm)
E ₁ : Longitudinal elastic modulus (elastic modulus) of core tube (N / mm ² )
E ₂ : Longitudinal elastic modulus (elastic modulus) of polyvinyl alcohol film (N / mm ² )
I ₁ : Secondary moment of inertia of the core tube (mm ^Four )
I ₂ : Cross-sectional second moment of polyvinyl alcohol film (mm ^Four )
x: Length from the end face of the core tube to an arbitrary cross section (mm)

  That is, in the polyvinyl alcohol film roll of the present invention, the core tube is made of carbon fiber reinforced plastic. Carbon fiber reinforced plastic has a specific gravity smaller than that of metal, and even if the core tube is elongated, an increase in the mass of the core tube is suppressed. For this reason, the polyvinyl alcohol-type film roll which wound the polyvinyl-alcohol-type film around the core pipe made from the carbon fiber reinforced plastic is excellent in the handleability. Moreover, since the elastic modulus of the core tube is set to 98 GPa (gigapascal) or more, even if the core tube is lengthened, the bending is extremely small, and the rotational vibration of the core tube is suppressed in the winding process. The polyvinyl alcohol film wound around the core tube is excellent in appearance without wrinkles.

  And in the process of manufacturing the polarizing film, when the polyvinyl alcohol film is fed out from the polyvinyl alcohol film roll, the rotation of the polyvinyl alcohol film roll is suppressed, and the polyvinyl alcohol film roll is fed out without wrinkles or breakage. Can do. For this reason, the polarizing film is excellent in uniformity in optical performance such as polarization performance without streaking or uneven dyeing. Further, the polarizing plate provided with a protective film on at least one surface of the polarizing film naturally has excellent uniformity in optical performance such as polarization performance.

  The polyvinyl alcohol film roll of the present invention is formed by winding a polyvinyl alcohol film on the outer peripheral surface of a cylindrical core tube, and the core tube is made of carbon fiber reinforced plastic. A material having an elastic modulus of 98 GPa or more is used. For this reason, even if the said core pipe is lengthened, while a mass increase is suppressed, the bending is very little. Therefore, the polyvinyl alcohol film roll in which the polyvinyl alcohol film is wound around the core tube has excellent handleability, and the wound polyvinyl alcohol film has excellent appearance with no wrinkles or the like. It has become.

  In particular, when the carbon fiber constituting the carbon fiber reinforced plastic has an elastic modulus of 196 GPa or more and a specific gravity of 0.5 to 3.0, the core tube is made more rigid and lightweight, and the core tube and polyvinyl alcohol The handleability of the system film roll is further improved.

  Further, when the core tube is formed by press-fitting a metal material cylinder on the outer periphery, the metal material cylinder increases the impact resistance of the core tube and makes it more resistant to impact during transportation. . Furthermore, the cylindrical body made of the metal material also increases the rigidity of the core tube and further suppresses the bending. Therefore, the rotational vibration of the core tube during winding is further reduced, and the wound polyvinyl alcohol film is It has become even better.

  Similarly, when the core tube is coated with a resin on the outer periphery, the coated resin increases the impact resistance and rigidity of the core tube, and is strong against impact during transportation. Furthermore, since the rigidity of the core tube is increased and the bending is further suppressed, the rotational vibration of the core tube during winding is further reduced, and the wound polyvinyl alcohol film is more excellent with no wrinkles or the like. It has become.

  Furthermore, when the roundness of the core tube is 0.01 to 1 mm and the cylindricity is 0.01 to 1 mm, the core tube has a smaller runout at the time of winding. The polyvinyl alcohol film is even better without wrinkles.

  Further, when the outer diameter of the core tube is 75 to 300 mm and the cylinder length is 0.5 to 6.0 m, the handling becomes easy and the workability and productivity are good.

The polarizing film obtained by using a polyvinyl alcohol-based film fed out from the top Symbol polyvinyl alcohol film roll from wrinkles or bending or the like, such Ikoto its polyvinyl alcohol film, no such streaks or uneven dyeing, Excellent polarization performance and the like.

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

The polyvinyl alcohol film roll (hereinafter abbreviated as “roll”) of the present invention is made of carbon fiber reinforced plastic, and has a cylindrical core having an elastic modulus E ₁ of 98 GPa or more calculated using the above formula (1). It consists of a tube and a polyvinyl alcohol film wound on the outer peripheral surface of the core tube.

  The core tube is manufactured by forming a carbon fiber reinforced plastic into a cylindrical shape by a sheet winding method. That is, first, a sheet body (prepreg) is produced by impregnating a thermosetting resin into a carbon cloth obtained by plain weaving or twill weaving of carbon fibers. Next, the sheet body (prepreg) is wound around one or more layers on the outer peripheral surface of a columnar or cylindrical mold, and then heated in a furnace (for example, 130 ° C. × 2 hours). Thereby, a carbon fiber reinforced plastic cured in a cylindrical shape is formed on the outer peripheral surface of the mold. And after extracting the cylindrical carbon fiber reinforced plastic from the said metal mold | die, it can carry out surface grinding | polishing as needed and can obtain the said core pipe. In addition, you may manufacture the said core pipe by a filament winding system as manufacturing methods other than the above. This manufacturing method is a method for obtaining the core tube by heating the carbon fiber around the outer peripheral surface of a cylindrical mold or the like while being immersed in a thermosetting resin bath, followed by heating in the same manner as described above.

  And the elasticity modulus of the manufactured core pipe is set to 98 GPa or more, and preferably from 98 to 294 GPa, more preferably from 118 to 245 GPa, from the viewpoint of using practical carbon fibers. . The elastic modulus of the core tube is determined by the elastic modulus of the carbon fiber used when the core tube (carbon fiber reinforced plastic) is manufactured, and the mold when the sheet body (prepreg) or the carbon fiber is wound around the mold. It can be performed by adjusting the direction of the carbon fiber relative to the axis of the carbon fiber (the direction of the carbon fiber relative to the axis of the core tube). However, when a fiber is wound in a certain direction (angle), it is brittle with respect to a force perpendicular to the direction, and is usually wound at an angle of two or more directions.

  Although it does not specifically limit as said carbon fiber, From a viewpoint of high rigidity and weight reduction, an elasticity modulus is 196 GPa or more (from a viewpoint which is a practical carbon fiber, More preferably, it is the range of 196-784 GPa), and specific gravity is 0. It is preferably set within the range of .5 to 3.0 (more preferably from 1.0 to 2.5 from the viewpoint of practical carbon fiber). When the elastic modulus of the carbon fiber is less than 196 GPa, it becomes difficult to ensure the rigidity of the core tube, and when the specific gravity of the carbon fiber is less than 0.5, the elastic modulus of the carbon fiber is usually low. This is because it is difficult to ensure the rigidity, and if the specific gravity exceeds 3.0, it is difficult to reduce the weight. Two or more carbon fibers having different elastic moduli may be used in combination.

  The thermosetting resin used for producing the core tube (carbon fiber reinforced plastic) is not particularly limited, but is usually epoxy resin, urethane resin, urea resin, silicone resin, unsaturated polyester resin, Examples include phenolic resin, melamine resin, nylon resin, alkyd resin, and the like. Among these, an epoxy resin is preferable from the viewpoint of achieving high rigidity due to a synergistic effect with the carbon fiber.

  Although the outer diameter and cylindrical length (axial length) of the core tube depend on the width of the polyvinyl alcohol film to be wound, etc., the outer diameter is in the range of 75 to 300 mm and the cylindrical length is 0.5. It is preferable to set within a range of ˜6.0 m. Particularly preferably, the outer diameter is 85 to 250 mm and the cylinder length is in the range of 0.5 to 5.0 m. That is, if the outer diameter is less than 75 mm, the core tube is easily bent, and if it exceeds 300 mm, the diameter becomes too large to be handled easily, and an unnecessarily large feeding device is required in the polarizing film manufacturing process. It is. On the other hand, if the cylindrical length is less than 0.5 m, the polarizing film width obtained in the polarizing film manufacturing process becomes very narrow, and thus the productivity tends to decrease. If it exceeds 6.0 m, the mass of the core tube increases. This is because there is a tendency that the workability is lowered due to the fact that it becomes too much.

  The thickness of the core tube is set in consideration of the outer diameter and cylindrical length of the core tube. That is, the smaller the outer diameter of the core tube and the longer the cylindrical length of the core tube, the greater the deflection of the core tube. Therefore, in order to reduce the deflection, it is necessary to increase the thickness. Therefore, when the outer diameter and the cylindrical length of the core tube have values within the above preferable ranges, the thickness of the core tube is set within a range of 5 to 20 mm. In particular, when a carbon fiber having an elastic modulus of 196 GPa or more (preferably in a range of 196 to 784 GPa) is used as the carbon fiber used in manufacturing the core tube (carbon fiber reinforced plastic), the thickness of the core tube is reduced. And is set within a range of 3 to 15 mm.

  Furthermore, it is preferable to use the core tube having a roundness of 0.01 to 1 mm and a cylindricity of 0.01 to 1 mm. More preferably, the roundness is in the range of 0.01 to 0.2 mm, the cylindricity is in the range of 0.01 to 0.2 mm, and particularly preferably, the roundness is in the range of 0.01 to 0.1 mm. And the cylindricity is in the range of 0.01 to 0.1 mm. That is, when the roundness exceeds 1 mm, the cross-section approaches an ellipse or the like, and when the winding is performed, the rotational vibration of the core tube at the time of winding increases, and wrinkles tend to occur. In addition, if the cylindricity exceeds 1 mm, the rotational deflection of the core tube during winding becomes large, and wrinkles and winding deviation tend to occur. In the present invention, the roundness is a value measured according to JIS H 0500, and refers to the difference between the maximum outer diameter and the minimum outer diameter measured in an arbitrary cross section of the core tube. The cylindricity is a value measured according to JIS B 0182, and refers to the difference between the minimum cylinder diameter and the maximum cylinder diameter.

  On the other hand, the polyvinyl alcohol film is usually produced as follows.

  That is, first, the polyvinyl alcohol resin used as a film raw material is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate, but is not limited thereto, and a small amount of unsaturated carboxylic acid (salt, Ester, amide, nitrile, etc.), olefins having 2 to 30 carbon atoms (ethylene, propylene, n-butene, isobutene, etc.), vinyl ethers, and unsaturated sulfonate modification components may be contained. In addition, a polyvinyl alcohol-based resin containing a silyl group may be used as a method for post-modification using a silylating agent, copolymerized with a silyl group-containing olefinically unsaturated monomer, or saponified. And the like. Examples of the silyl group-containing olefinically unsaturated monomer include vinyl silane, (meth) acrylamide, and alkyl silane.

  Although the weight average molecular weight of the said polyvinyl alcohol-type resin is not specifically limited, Preferably it is 80000-300000, More preferably, it is 110000-26000, More preferably, it exists in the range of 130000-200000. If the weight average molecular weight is less than 80000, sufficient optical performance cannot be obtained when a polyvinyl alcohol-based resin is used as an optical film. If it exceeds 300000, stretching is difficult when the film is used as a polarizing film. Is difficult and undesirable. In addition, the weight average molecular weight of polyvinyl alcohol-type resin is measured by GPC-LALLS method.

  Furthermore, it is preferable that the saponification degree of polyvinyl alcohol-type resin is 80 mol% or more, More preferably, it is 85-100 mol%, Most preferably, it is 98-100 mol%. Thus, when the degree of saponification is less than 80 mol%, it is not preferable because sufficient polarization performance is difficult to obtain in the case of a polarizing film.

  If necessary, the polyvinyl alcohol-based resin may contain 30 wt% of commonly used plasticizers such as glycerin, diglycerin, triglycerin, ethylene glycol, triethylene glycol, and polyethylene glycol with respect to the polyvinyl alcohol-based resin. % Or less, more preferably 3 to 25% by weight, particularly preferably 5 to 20% by weight. That is, when the plasticizer exceeds 30% by weight, the film strength tends to be inferior, which is not preferable.

  More preferably, a nonionic, anionic or cationic surfactant, particularly preferably a release agent such as polyoxyethylene alkylamino ether is 5% by weight or less with respect to the polyvinyl alcohol resin, more preferably. It is contained in an amount of 0.001 to 3% by weight, particularly preferably 0.001 to 2% by weight. That is, if the release agent exceeds 5% by weight, the appearance of the film surface tends to be poor, which is not preferable.

  The sodium acetate contained in the polyvinyl alcohol resin powder is removed (devinegared) because it adversely affects the optical performance. This removal of sodium acetate (devinegaring) is usually performed by adding water to the polyvinyl alcohol resin in a devinegaring tank.

  Next, since it becomes difficult to obtain a desired high-concentration polyvinyl alcohol-based resin aqueous solution by adding the water, it is dehydrated. As a dehydrating method, a continuous centrifugal dehydrator is used. Thereby, the said polyvinyl alcohol-type resin becomes cake shape.

  And by melt | dissolving under pressure by blowing water vapor (about 110-160 degreeC) in the cake-like polyvinyl alcohol-type resin in a melt | dissolution can, the polyvinyl alcohol-type resin aqueous solution is prepared. At this time, a plasticizer, an additive, etc. are added as needed. Thereby, a polyvinyl alcohol-based resin aqueous solution having a water content of about 20 to 40% by weight is obtained.

  Next, the obtained polyvinyl alcohol-based resin aqueous solution is filtered to remove impurities, and then defoamed. As the defoaming treatment method, a stationary defoaming method or a defoaming treatment method using a multi-screw extruder is used, and a defoaming treatment method using a multi-screw extruder is preferred.

  Next, after the defoamed polyvinyl alcohol resin aqueous solution is filtered again, it is supplied to the T-type slit die and extruded from the T-type slit die to flow down into a screen.

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

  Next, after peeling a film from the outer peripheral surface of a drum type roll, and passing between several drying rolls (about 60-100 degreeC), it heat-processes (about 100-140 degreeC). Next, apply the humidity controller as necessary. The water content of the film is preferably 5% by weight or less, particularly preferably 1 to 4% by weight. If it exceeds 5% by weight, it is not preferred because it tends to cause poor appearance during storage of the film. In this way, the desired polyvinyl alcohol film is obtained. The width of the resulting polyvinyl alcohol film is preferably 2.0 m or more, particularly 2.5 m or more, and more preferably 3.0 m or more from the viewpoint of productivity during the production of the polarizing film. The film thickness of the polyvinyl alcohol film is preferably 30 to 100 μm, more preferably 30 to 90 μm, and particularly preferably 30 to 70 μm from the viewpoint of thinning. When the film thickness is less than 30 μm, it is difficult to stretch the polarizing film and sufficient polarization performance cannot be obtained. When it exceeds 100 μm, the film thickness accuracy is lowered, which is not preferable. Further, the length of the polyvinyl alcohol film is preferably 2000 m or more, more preferably 3000 m or more, and particularly preferably 4000 m or more, and the upper limit is 15000 m or less, preferably 13000 m or less.

  And the core pipe which consists of said carbon fiber reinforced plastics is set to a winding machine. Since the core tube is made of carbon fiber reinforced plastic, it is relatively light and has excellent handleability when set in the winder, improving workability and productivity. Next, the winder is driven to rotate the core tube, and the obtained polyvinyl alcohol film is wound on the outer peripheral surface of the core tube. Since the elastic modulus of the core tube is set to 98 GPa or more (preferably in the range of 98 to 294 GPa, more preferably in the range of 118 to 245 GPa), the bending of the core tube is suppressed, and the core tube is When rotating, the rotational deflection of the core tube is small, and the polyvinyl alcohol film can be wound up without wrinkles or the like. Then, if necessary, the wound polyvinyl alcohol film is cut into a product width by a slitter. In this way, the roll of the present invention can be obtained.

  The roll of the present invention thus obtained is moved to the support base, and the left and right ends of the core tube are supported. Since the core tube is a lightweight one made of carbon fiber reinforced plastic as described above, the roll is relatively light and has excellent handling properties when moving to the support base, improving workability and productivity. To do. And it is stored or transported in the support state.

  As the core tube, from the viewpoint of improving the impact resistance and rigidity of the core tube, a cylindrical body made of a metal material such as a stainless steel pipe is pressurized on the outer periphery of the core tube (tube body) made of the carbon fiber reinforced plastic. The outer fitting may be newly used as a core tube. As a result, the impact resistance of the core tube is increased and the impact during transportation is increased. Furthermore, the rigidity of the core tube is also increased, and phenomena such as bending are further suppressed, so that the rotational vibration of the core tube during winding is further reduced, and the polyvinyl alcohol film is in a better state without generating wrinkles. Can be rolled up. In this case, the thickness of the metal material cylindrical body is preferably in the range of 0.1 to 5.0 mm (preferably 0.3 to 2.5 mm) from the viewpoint of suppressing an increase in mass of the core tube. . Further, the impact resistance and rigidity of the core tube can be improved by coating the outer periphery with a resin such as an epoxy resin in place of the press fitting of the metal material cylindrical body. In this case, the thickness of the resin to be coated is preferably in the range of 0.01 to 1.0 mm (preferably 0.05 to 0.5 mm) from the viewpoint of suppressing an increase in the mass of the core tube.

  When pressure fitting or resin coating of the cylindrical body made of the above metal material is performed, the rigidity of the core tube is improved, so that the elastic modulus is used as the carbon fiber used when manufacturing the carbon fiber reinforced plastic (tube body). You may use a thing with low.

  The polyvinyl alcohol film in the roll of the present invention 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 film will be described below.

  First, the roll of this invention is set to the polarizing film manufacturing apparatus from the said support stand. At this time, the roll is relatively light due to the weight reduction of the core tube, and is excellent in handling property when set in the polarizing film manufacturing apparatus, so that workability and productivity are improved. And the polyvinyl alcohol-type film is drawn out from the roll. At this time, since the elastic modulus of the core tube is set to 98 GPa or more (preferably in the range of 98 to 294 GPa, more preferably in the range of 118 to 245 GPa), the deflection of the roll is suppressed, and the polyvinyl alcohol film When the roll is fed out, the rotational runout of the roll is small, and the polyvinyl alcohol film can be fed out without wrinkles or breakage. Thereafter, the polyvinyl alcohol film is dyed, uniaxially stretched, and treated with a boron compound.

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

  The uniaxial stretching is preferably 3 to 10 times, more preferably 3.5 to 6 times. At this time, the film may be slightly stretched in the direction perpendicular to the uniaxial stretching (stretching to prevent shrinkage in the width direction or more). The temperature condition during uniaxial stretching is preferably set in the range of 40 to 170 ° C. Furthermore, the uniaxial stretching ratio may be finally set within 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 uniaxial stretching, simultaneously with uniaxial stretching, or after uniaxial stretching, but the polyvinyl alcohol film is dyeable as crystallization proceeds by uniaxial stretching. The dyeing is preferably performed before or simultaneously with uniaxial stretching.

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

  The polarizing film thus obtained can be used as a polarizing plate by laminating and bonding an optically isotropic polymer film or sheet as a protective film on one or both surfaces thereof. Examples of the protective film include cellulose triacetate, cellulose diacetate, polycarbonate, polymethyl methacrylate, polystyrene, polyethersulfone, polyarylene ester, poly-4-methylpentene, polyphenylene oxide, cyclo- or norbornene-based polyolefin. And the like. Further, the polarizing film may be laminated by applying a curable resin such as urethane resin, acrylic resin, urea resin, etc. on one or both sides of the polarizing film instead of the protective film. .

  Furthermore, the polarizing film (or a protective film or a curable resin laminated on at least one surface thereof) is practically used by forming a transparent pressure-sensitive adhesive layer on the one surface as required. In some cases, it is served. Examples of the pressure-sensitive adhesive layer include acrylic acid esters such as butyl acrylate, ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, acrylic acid, maleic acid, itaconic acid, methacrylic acid, and crotonic acid. Copolymers with α-monoolefin carboxylic acids (including those added with vinyl monomers such as acrylonitrile, vinyl acetate, and styrene) may interfere with the polarization performance of the polarizing film. However, the present invention is not limited to this, and any pressure-sensitive adhesive having transparency can be used. For example, polyvinyl ether, rubber, and the like can be used.

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

  Next, examples will be described together with comparative examples.

In the following Examples and Comparative Examples, the weight average molecular weight was measured under the following conditions by the GPC-LALLS method.
(A) GPC
Apparatus: Waters type 244 gel permeation chromatograph column: Tosoh TSK-gel-GMPWXL (inner diameter 8 mm, length 30 cm, two)
Solvent: 0.1 M Tris buffer (pH 7.9)
Flow rate: 0.5 ml / min
Temperature: 23 ° C
Material concentration: 0.040%
Filtration: 0.45 μm Mysori disk W-25-5 made by Tosoh
Injection volume: 0.2ml
Detection sensitivity (differential refractive index detector): 4 times (B) LALLS
Apparatus: Chromatrix KMX-6 type low angle laser light scattering photometer Temperature: 23 ° C
Wavelength: 633nm
Second virial coefficient × concentration: 0 mol / g
Refractive index density change (dn / dc): 0.159 ml / g
Filter: MILLIPORE 0.45 μm filter HAWP01300
Gain: 800mV

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

[Core tube]
An inner diameter of 152 mm made of carbon fiber reinforced plastic by a sheet winding method using pitch-based carbon fiber (DIALEAD (registered trademark) K6712, manufactured by Mitsubishi Chemical Corporation, elastic modulus 640 GPa, specific gravity 2.12) and epoxy resin. A core tube having an outer diameter of 172 mm and a cylindrical length of 4.5 m was produced. This core tube had a density of 1640 kg / m ³ , a mass of 38 kg, a roundness of 0.05 mm, a cylindricity of 0.03 mm, and a self-weight deflection (bending of the central portion when both end pins are supported, the same applies hereinafter) of 0.22 mm.

[Polyvinyl alcohol film]
Polyvinyl alcohol resin having a weight average molecular weight of 135,000 and a saponification degree of 99.7 mol%, glycerin as a plasticizer, and polyoxyethylene alkylamino ether as a surfactant (peeling agent). After preparing an aqueous resin solution (including a plasticizer and a release agent as a solid content), the film was cast from a T-type slit die with a drum-type roll, dried, heat-treated and conditioned to a moisture content of 4% by weight and a width of 4300 mm. A polyvinyl alcohol film having a thickness of 75 μm was prepared.

[Production of roll: winding of polyvinyl alcohol film]
Then, as shown in FIG. 1, 6000 m of the polyvinyl alcohol film 2 was wound around the outer peripheral surface of the core tube 1. At this time, the winding tension (tension per 1 m width of the polyvinyl alcohol film) was 130 N / m, and the winding speed was 80 m / min. Moreover, the self-weight deflection of the roll after finishing winding was 8.5 mm.

ここで、
Ｌ ：芯管の長さ（ｍｍ）〔Ｌ＝Ｌ₁ ×２＋Ｌ₂ 〕
Ｌ₁ ：芯管の端面からフィルムの端面までの長さ（ｍｍ）
Ｌ₂ ：ポリビニルアルコール系フィルムの幅（ｍｍ）
Ｗ₁ ：芯管の等分布荷重（Ｎ／ｍｍ）
Ｗ₂ ：芯管＋フィルムの等分布荷重（Ｎ／ｍｍ）
Ｅ₁ ：芯管の縦弾性係数（弾性率）（Ｎ／ｍｍ² ）
Ｅ₂ ：ポリビニルアルコール系フィルムの縦弾性係数（弾性率）（Ｎ／ｍｍ² ）
Ｉ₁ ：芯管の断面２次モーメント（ｍｍ⁴ ）
Ｉ₂ ：ポリビニルアルコール系フィルムの断面２次モーメント（ｍｍ⁴ ）
ｘ ：芯管の端面から任意の断面までの長さ（ｍｍ） Next, the elastic modulus E ₁ of the core tube was calculated using the following formula (1).

here,
L: Length of core tube (mm) [L = L ₁ × 2 + L ₂ ]
L ₁ : Length from the end face of the core tube to the end face of the film (mm)
L ₂ : width of the polyvinyl alcohol film (mm)
W ₁ : Uniformly distributed load of core tube (N / mm)
W ₂ : Uniform distribution load of core tube + film (N / mm)
E ₁ : Longitudinal elastic modulus (elastic modulus) of core tube (N / mm ² )
E ₂ : Longitudinal elastic modulus (elastic modulus) of polyvinyl alcohol film (N / mm ² )
I ₁ : secondary moment of inertia of the core tube (mm ⁴ )
I ₂ : Secondary moment of inertia of the polyvinyl alcohol film (mm ⁴ )
x: Length from the end face of the core tube to an arbitrary cross section (mm)

That is, in Example 1, by substituting the following values into the above formula (1), it was calculated that the elastic modulus E ₁ of the core tube was 118 GPa (= 18000 N / mm ² ).
Self-weight deflection of core tube δ = 0.22mm
Core tube length L = 4500 mm (L ₁ = 100 mm, L ₂ = 4300 mm)
Uniformly distributed load of core tube W ₁ = W ₂ = 0.0819 N / mm
Longitudinal elastic modulus (elastic modulus) of polyvinyl alcohol film E ₂ = 100 N / mm ²
The secondary moment of inertia of the core tube I ₁ = 1.676 × 10 ⁷ mm ⁴
Sectional moment of inertia of polyvinyl alcohol film I ₂ = 0mm ⁴

(Preparation of polarizing film)
Next, the wound polyvinyl alcohol film was drawn out at a rate of 1.23 m / min, swollen in a water washing tank (24 ° C.), and then swollen in an iodine tank (20 ° C., iodine 0.17 g / liter). Eight times, uniaxially stretching 2.0 times in a boric acid bath (50 ° C., 8 ppm iodine, 47 g / liter boric acid), and further uniaxially stretching 5.2 times at a winding speed of 6.4 m / min. A polarizing film was prepared.

[Example 2]
In the same manner as in Example 1, a polyvinyl alcohol film was produced and wound around the following core tube. The self-weight deflection of the roll after finishing the winding was 6.8 mm. Thereafter, a polarizing film was produced in the same manner as in Example 1.

[Core tube]
First, using pitch-based carbon fiber [Dialead (registered trademark) K63712, manufactured by Mitsubishi Chemical Corporation, elastic modulus 640 GPa, specific gravity 2.12] and an epoxy resin, and made of carbon fiber reinforced plastic by sheet winding method, A tube having an inner diameter of 152 mm, an outer diameter of 173.8 mm, and a cylinder length of 4.5 m was produced. Then, a stainless steel pipe having a thickness of 0.6 mm and a cylinder length of 4.5 m was press-fitted around the outer periphery of the tubular body to produce a core tube having an outer diameter of 175 mm. This core tube had a density of 1988 kg / m ³ , a mass of 50 kg, a roundness of 0.07 mm, a cylindricity of 0.08 mm, and a self-weight deflection of 0.20 mm.

In Example 2, it was calculated that the elastic modulus E ₁ of the core tube was 157 GPa (= 157000 N / mm ² ) by substituting the following values into the above formula (1).
Self-weight deflection of core tube δ = 0.20mm
Core tube length L = 4500 mm (L ₁ = 100 mm, L ₂ = 4300 mm)
Uniformly distributed load of the core tube W ₁ = W ₂ = 0.1088 N / mm
Longitudinal elastic modulus (elastic modulus) of polyvinyl alcohol film E ₂ = 100 N / mm ²
Second moment of inertia of core tube I ₁ = 1.859 × 10 ⁷ mm ⁴
Sectional moment of inertia of polyvinyl alcohol film I ₂ = 0mm ⁴

Example 3
In the same manner as in Example 1, a polyvinyl alcohol film was produced and wound around the following core tube. The self-weight deflection of the roll after finishing winding was 7.1 mm. Thereafter, a polarizing film was produced in the same manner as in Example 1.

[Core tube]
First, using pitch-based carbon fiber [Dialead (registered trademark) K63712, manufactured by Mitsubishi Chemical Corporation, elastic modulus 640 GPa, specific gravity 2.12] and an epoxy resin, and made of carbon fiber reinforced plastic by sheet winding method, A tube having an inner diameter of 152 mm, an outer diameter of 173.8 mm, and a cylinder length of 4.5 m was produced. Then, an epoxy conductive resin was coated on the outer peripheral surface of the tubular body by dipping (thickness 0.6 mm), and after curing, the surface was polished to produce a core tube having an outer diameter of 175 mm. The core tube had a mass of 40 kg, a roundness of 0.05 mm, a cylindricity of 0.06 mm, and a self-weight deflection of 0.17 mm.

In Example 3, by substituting the following values into the above formula (1), it was calculated that the elastic modulus E ₁ of the core tube was 147 GPa (= 147000 N / mm ² ).
Self-weight deflection of core tube δ = 0.17mm
Core tube length L = 4500 mm (L ₁ = 100 mm, L ₂ = 4300 mm)
Uniformly distributed load of the core tube W ₁ = W ₂ = 0.0881 N / mm
Longitudinal elastic modulus (elastic modulus) of polyvinyl alcohol film E ₂ = 100 N / mm ²
Second moment of inertia of core tube I ₁ = 1.859 × 10 ⁷ mm ⁴
Sectional moment of inertia of polyvinyl alcohol film I ₂ = 0mm ⁴

Example 4
As shown below, after producing a polyvinyl alcohol-based film, the polyvinyl alcohol-based film was wound up to 9000 m on the core tube of Example 2 above. The self-weight deflection of the roll after finishing winding was 6.8 mm. Thereafter, a polarizing film was produced in the same manner as in Example 1.

[Polyvinyl alcohol film]
Polyvinyl alcohol resin having a weight average molecular weight of 135,000 and a saponification degree of 99.7 mol%, glycerin as a plasticizer, and polyoxyethylene alkylamino ether as a surfactant (peeling agent). After preparing an aqueous resin solution (including a plasticizer and a release agent as a solid content), the film was cast from a T-type slit die with a drum-type roll, dried, heat-treated and conditioned to a moisture content of 4% by weight and a width of 4300 mm. A polyvinyl alcohol film having a thickness of 50 μm was prepared.

Example 5
As shown below, after producing a polyvinyl alcohol-based film, the polyvinyl alcohol-based film was wound up to 9000 m on the core tube of Example 2 above. The self-weight deflection of the roll after finishing winding was 6.8 mm. Thereafter, a polarizing film was produced in the same manner as in Example 1.

[Polyvinyl alcohol film]
Polyvinyl alcohol resin having a weight average molecular weight of 175000 and a saponification degree of 99.7 mol%, glycerin as a plasticizer, and polyoxyethylene alkylamino ether as a surfactant (peeling agent) After preparing an aqueous resin solution (including a plasticizer and a release agent as a solid content), the film was cast from a T-type slit die with a drum-type roll, dried, heat-treated and conditioned to a moisture content of 4% by weight and a width of 4300 mm. A polyvinyl alcohol film having a thickness of 50 μm was prepared.

[Comparative Example 1]
In the same manner as in Example 1, a polyvinyl alcohol film was produced and wound around the following core tube. At the time of winding, wrinkles were confirmed at the center of the polyvinyl alcohol film, but the winding was continued as it was. The self-weight deflection of the roll after finishing the winding was 10.2 mm. Thereafter, a polarizing film was produced in the same manner as in Example 1. When the polyvinyl alcohol film was unwound, the wrinkle portion was broken by a nip roll, and the portion became streaks or uneven dyeing.

[Core tube]
An aluminum core tube having an inner diameter of 152 mm, an outer diameter of 175 mm, and a cylinder length of 4.5 m was produced. The aluminum core tube had a specific gravity of 2.7, a mass of 72 kg, a roundness of 0.10 mm, a cylindricity of 0.14 mm, and a self-weight deflection of 0.61 mm.

In this comparative example 1, it was calculated that the elastic modulus E ₁ of the core tube was 69 GPa (= 69000 N / mm ² ) by substituting the following values into the above formula (1).
Self-weight deflection of core tube δ = 0.61mm
Core tube length L = 4500 mm (L ₁ = 100 mm, L ₂ = 4300 mm)
Uniformly distributed load of core tube W ₁ = W ₂ = 0.1564 N / mm
Longitudinal elastic modulus (elastic modulus) of polyvinyl alcohol film E ₂ = 100 N / mm ²
Second moment of inertia I ₁ = 1.984 × 10 ⁷ mm ^{4 of} core tube
Sectional moment of inertia of polyvinyl alcohol film I ₂ = 0mm ⁴

[Comparative Example 2]
In the same manner as in Example 1, a polyvinyl alcohol film was produced and wound around the following core tube. At the time of winding, a slight wrinkle was observed at the center of the polyvinyl alcohol film, but the winding was continued as it was. The self-weight deflection of the roll after finishing winding was 8.9 mm. Thereafter, a polarizing film was produced in the same manner as in Example 1. When the polyvinyl alcohol film was unwound, the wrinkle portion was broken by a nip roll, and the portion became streaks or uneven dyeing.

[Core tube]
Using a pitch-based carbon fiber [DIALEAD (registered trademark) K63312, manufactured by Mitsubishi Chemical Industries, Ltd., elastic modulus 640 GPa, specific gravity 2.12] and an epoxy resin, a sheet winding method (however, in Comparative Example 2, the above implementation A core tube made of carbon fiber reinforced plastic and having an inner diameter of 152 mm, an outer diameter of 175 mm, and a cylinder length of 4.5 m was prepared. This core tube had an elastic modulus of 90 GPa, a mass of 44 kg, a roundness of 0.05 mm, a cylindricity of 0.04 mm, and a self-weight deflection of 0.28 mm.

In this comparative example 2, it was calculated that the elastic modulus E ₁ of the core tube was 90 GPa (= 90000 N / mm ² ) by substituting the following values into the above formula (1).
Self-weight deflection of core tube δ = 0.28mm
Core tube length L = 4500 mm (L ₁ = 100 mm, L ₂ = 4300 mm)
Uniformly distributed load of core tube W ₁ = W ₂ = 0.0950 N / mm
Longitudinal elastic modulus (elastic modulus) of polyvinyl alcohol film E ₂ = 100 N / mm ²
Second moment of inertia I ₁ = 1.984 × 10 ⁷ mm ^{4 of} core tube
Sectional moment of inertia of polyvinyl alcohol film I ₂ = 0mm ⁴

  The polyvinyl alcohol films and polarizing films of Examples 1 to 5 and Comparative Examples 1 and 2 thus obtained were evaluated according to the methods shown below. The results are shown in Table 1 below.

[Presence or absence of wrinkle formation when winding a polyvinyl alcohol film]
The presence or absence of wrinkle formation of each polyvinyl alcohol film at the time of winding was visually evaluated. And what evaluated the formation of a wrinkle as (circle) and what confirmed the formation of a wrinkle was evaluated as x, and it described in Table 1 below.

[Stripes and polarization unevenness in polarizing film]
The streaks and dyeing unevenness in the polarizing film were visually evaluated. As a result, the case where neither streak nor dyeing unevenness was confirmed was evaluated as ◯, and the case where either one was confirmed was evaluated as ×, and the results were also shown in Table 1 below.

[Optical characteristics of polarizing film]
Using “Σ90” manufactured by Nippon Denshoku Industries Co., Ltd. as a measuring device, the optical characteristics (single transmittance and degree of polarization) of the polarizing film were measured. In this measurement, five points were measured at equal intervals in the width direction of the polarizing film, and the maximum value, the minimum value, and the average value were also shown in Table 1 below.

  From the result of the said Table 1, in Examples 1-5, wrinkles did not generate | occur | produce in a polyvinyl-alcohol-type film, and neither a streak nor dyeing | staining unevenness generate | occur | produced also in the polarizing film. On the other hand, in Comparative Examples 1 and 2, wrinkles were generated in the polyvinyl alcohol film, the feeding of the polyvinyl alcohol film was not stable, and uniform stretching could not be performed. For this reason, uneven dyeing occurred. It can be seen that this is because the comparative example 1 and 2 are larger in the self-weight deflection of the core tube and the self-weight deflection of the roll than in Examples 1-5. Further, the optical characteristics (single transmittance and degree of polarization) of the polarizing film have little variation in the width direction and excellent in-plane uniformity in Examples 1 to 5. As a result, the yield can be improved and the quality of wide products can be handled. On the other hand, in Comparative Examples 1 and 2, since the variation in the width direction is large, the yield is lowered and the wide product cannot be handled. It can be seen that this is also because the self-weight deflection of the core tube and the self-weight deflection of the roll are larger in Comparative Examples 1 and 2 than in Examples 1-5.

It is explanatory drawing which shows the Example of the polyvinyl alcohol-type film roll of this invention.

Claims (6)

A polyvinyl alcohol film roll formed by winding a polyvinyl alcohol film on the outer peripheral surface of a cylindrical core tube, wherein the core tube is made of carbon fiber reinforced plastic, and is calculated using the following formula (1). The polyvinyl alcohol film roll characterized in that the elastic modulus (E ₁ ) of the core tube is 98 GPa or more.

here,
L: Length of core tube (mm) [L = L ₁ × 2 + L ₂ ]
L ₁ : Length from the end face of the core tube to the end face of the film (mm)
L ₂ : width of the polyvinyl alcohol film (mm)
W ₁ : Uniformly distributed load of core tube (N / mm)
W ₂ : Uniform distribution load of core tube + film (N / mm)
E ₁ : Longitudinal elastic modulus (elastic modulus) of core tube (N / mm ² )
E ₂ : Longitudinal elastic modulus (elastic modulus) of polyvinyl alcohol film (N / mm ² )
I ₁ : secondary moment of inertia of the core tube (mm ⁴ )
I ₂ : Secondary moment of inertia of the polyvinyl alcohol film (mm ⁴ )
x: Length from the end face of the core tube to an arbitrary cross section (mm)   The polyvinyl alcohol film roll according to claim 1, wherein the carbon fiber constituting the carbon fiber reinforced plastic has an elastic modulus of 196 GPa or more and a specific gravity of 0.5 to 3.0.   The polyvinyl alcohol film roll according to claim 1 or 2, wherein the core tube is formed by press-fitting a metal material cylinder on the outer periphery.   The polyvinyl alcohol film roll according to claim 1 or 2, wherein the core tube is formed by coating an outer peripheral surface with a resin.   The polyvinyl alcohol film roll according to any one of claims 1 to 4, wherein the roundness of the core tube is 0.01 to 1 mm and the cylindricity is 0.01 to 1 mm.   The polyvinyl alcohol film roll according to any one of claims 1 to 5, wherein the core tube has an outer diameter of 75 to 300 mm and a cylindrical length of 0.5 to 6.0 m.

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