TWI795590B - Polyvinyl alcohol-based film roll and its manufacturing method - Google Patents

Abstract

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Description

Polyvinyl alcohol-based film roll and its manufacturing method

The present invention relates to a polyvinyl alcohol-based film roll obtained by winding a polyvinyl alcohol-based film used as a material for forming a polarizing film around a core tube, and a manufacturing method thereof.

A polyvinyl alcohol-based film is used in various applications as a film excellent in transparency, and one of the useful applications thereof is a polarizing film. This polarizing film is used as a basic component of a liquid crystal display.

The above-mentioned polyvinyl alcohol-based film is generally formed into a long strip shape by continuous casting using a polyvinyl alcohol-based resin aqueous solution as a forming material, and the ends on both sides are cut off (cut off) to make the width a design value. ) and manufactured, and then wound up on a cylindrical core pipe using a winding machine. The winding machine is equipped with a control roller (called a touch roller, contact roller, etc.) in a state of contacting or approaching the above-mentioned core tube, and the above-mentioned polyvinyl alcohol-based film is wound on the above-mentioned control roller after contacting the control roller. Core pipe (for example, refer to Patent Documents 1 and 2). In addition, the above-mentioned winding state can be controlled by the control roller. In this manner, a polyvinyl alcohol-based film roll composed of the core tube and the polyvinyl alcohol-based film wound around the core tube can be obtained.

The above-mentioned polarizing film is produced by drawing out a polyvinyl alcohol-based film from the above-mentioned polyvinyl alcohol-based film roll, and passing through a swelling step, a dyeing step, and a stretching step for the polyvinyl alcohol-based film. [Prior Technical Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2004-106376 [Patent Document 2] International Publication No. 2017/038955

[Problem to be solved by the invention]

Recently, the size of the above-mentioned liquid crystal display has been increasing. Along with this, the size of the above-mentioned polarizing film, which is a basic component of the liquid crystal display, has increased, and furthermore, the above-mentioned polyvinyl alcohol-based film, which is a material for forming the polarizing film, has become longer and wider. In progress.

However, if the above-mentioned polyvinyl alcohol-based film produced is elongated and widened, the polarizing film produced using the polyvinyl alcohol-based film as a forming material may cause color spots, etc., and the performance of the polarizing film may deteriorate. Case. This tendency becomes remarkable when the said polyvinyl-alcohol-type film is thin.

Then, the inventors of the present invention investigated the reason why the performance of the polarizing film deteriorated due to the elongation and width of the polyvinyl alcohol-based film. As a result, it was found that the roll of the above-mentioned polyvinyl alcohol-based film has significant wrinkles and eccentricity (deviation of the outer diameter of the wound polyvinyl alcohol-based film) that have not been seen so far. Therefore, when the polyvinyl alcohol-based film is pulled out from the roll of the above-mentioned polyvinyl alcohol-based film when the polarizing film is produced, the polyvinyl alcohol-based film has wrinkles, or the drawn-out state becomes uneven due to the above-mentioned eccentricity. The inventors of the present invention have found that this will lead to deterioration of the performance of the manufactured polarizing film. In this regard, the above-mentioned polyvinyl alcohol-based film roll has room for improvement.

The present invention is made in view of such circumstances, and aims to provide a polyvinyl alcohol film roll and a polyvinyl alcohol film roll that does not cause wrinkles and eccentricity even if the polyvinyl alcohol film wound on the core tube is elongated and widened. Its method. [Means to solve the problem]

In order to achieve the above objects, the inventors of the present application further conducted studies on polyvinyl alcohol-based film rolls in view of the findings obtained as described above. As a result, it was found that the winding hardness of a polyvinyl alcohol-based film roll having significant wrinkles and eccentricity greatly differs depending on the position in the width direction of the polyvinyl alcohol-based film. In addition, it was found that if the polyvinyl alcohol-based film is wound on the core tube so as to reduce the variation in the winding hardness in the width direction, the wrinkling and eccentricity of the polyvinyl alcohol-based film roll can be suppressed, and a product with excellent appearance shape can be obtained. Polyvinyl alcohol-based film roll.

That is, the gist of the present invention is the following [1] to [8]. [1] A polyvinyl alcohol-based film roll comprising: A core tube with an axial length of more than 3.5m, and A polyvinyl alcohol-based film with a width of 3.5 m or more, a thickness of 60 μm or less, and a length of 5,000 m or more wound around the core tube; The variation in winding hardness in the width direction of the polyvinyl alcohol-based film is 15 or less in durometer hardness. [2] The polyvinyl alcohol-based film roll according to [1] above, wherein the winding hardness falls within a range of 60 to 95 durometer hardness. [3] The polyvinyl alcohol-based film roll according to the above [1] or [2], wherein the moisture content of the polyvinyl alcohol-based film is 5% by weight or less. [4] A method of manufacturing a polyvinyl alcohol-based film roll, which is to arrange a first control roll and a second control roll in parallel with the core tube in the vicinity of a core tube with a length of 3.5 m or more in the axial direction, so that the above-mentioned The core tube is rotated so that the polyvinyl alcohol-based film with a width of 3.5 m or more, a thickness of 60 μm or less, and a length of 5000 m or more is wound around the core tube while contacting at least one of the first control roll and the second control roll, and Obtaining the polyvinyl alcohol-based film roll according to any one of the above-mentioned [1] to [3] comprising the above-mentioned core tube and the above-mentioned polyvinyl alcohol-based film wound around the core tube, During winding, as the outer diameter of the polyvinyl alcohol-based film wound on the rotating core tube increases, the core tube is gradually moved away from the first control roll and the second control roll, Wherein, the above-mentioned polyvinyl alcohol-based film is wound up on the above-mentioned core pipe while contacting the above-mentioned first control roller until a predetermined time point between the start of winding and the end of winding, After the predetermined time point until the winding is completed, the polyvinyl alcohol-based film is wound around the core tube while contacting the second control roll without contacting the first control roll, Thereby, the entry angle of the polyvinyl alcohol-based film is maintained within a range of 2 to 35° from the start of winding to the end of winding. [5] The method for producing a roll of a polyvinyl alcohol-based film according to [4] above, wherein the first control roll and the second control roll are positionally adjustable independently of each other. [6] The method for producing a polyvinyl alcohol-based film roll according to the above [4] or [5], wherein the winding tension of the polyvinyl alcohol-based film wound on the core tube is maintained in the range of 100 to 300 N/m Inside. [7] The method for producing a roll of a polyvinyl alcohol-based film according to any one of [4] to [6] above, wherein the distance between the outer peripheral surface of the polyvinyl alcohol-based film wound around the core tube and the first control roll is The gap between the outer peripheral surfaces is maintained within the range of 2-10mm. [8] The method for producing a polyvinyl alcohol-based film roll according to any one of [4] to [7] above, wherein the winding speed of the polyvinyl alcohol-based film is 35 m/min or more.

Here, the "deviation" of the winding hardness of the polyvinyl alcohol-based film in the width direction of the polyvinyl alcohol-based film roll of the present invention is measured on the shortest distance from one end to the other end in the width direction. The difference between the maximum value and the minimum value of the winding hardness obtained from multiple locations. Also, the "entry angle" of the polyvinyl alcohol-based film in the manufacturing method of the polyvinyl alcohol-based film roll of the present invention, as shown in Figs. The angle (α, β of Figure 3). [Effect of the invention]

In the polyvinyl alcohol-based film roll of the present invention, the variation in winding hardness in the width direction of the polyvinyl alcohol-based film wound on the core tube is 15 or less in durometer hardness. Therefore, even if the above-mentioned polyvinyl alcohol-based film has a wide width of 3.5 m or more and a long strip with a length of 5000 m or more, it is wound in a uniform state. Furthermore, even if the above-mentioned polyvinyl alcohol-based film is thin with a thickness of 60 μm or less, it maintains its uniform roll state. That is, the roll of the polyvinyl alcohol-based film of the present invention has almost no wrinkles or eccentricity. Therefore, when the polyvinyl alcohol-based film is drawn out from the roll of the polyvinyl alcohol-based film of the present invention when producing a polarizing film, the polyvinyl alcohol-based film has no wrinkles and can be drawn out uniformly. As a result, a polarizing film having excellent performance free from color unevenness and the like can be obtained.

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

[Polyvinyl alcohol-based film roll] Fig. 1 is a perspective view showing an embodiment of a polyvinyl alcohol-based film roll of the present invention. The polyvinyl alcohol-based film roll includes: a core tube 1 having an axial length of 3.5 m or more; and polyvinyl alcohol having a width of 3.5 m or more, a thickness of 60 μm or less, and a length of 5000 m or more wound on the outer peripheral surface of the core tube 1 Department of film 2. In addition, the variation in winding hardness in the width direction of the polyvinyl alcohol-based film 2 is 15 or less in durometer hardness. This is one of the major features of the present invention. With this characteristic configuration, even if the polyvinyl alcohol-based film 2 to be wound is wide, long, and thin as described above, the above-mentioned polyvinyl alcohol-based film roll has almost no wrinkles or eccentricity, and the polyvinyl alcohol-based film 2 Coiled in a uniform state. In addition, in FIG. 1, in order to make the structure of the said polyvinyl-alcohol-type film roll easy to understand, each structure is shown schematically, and the ratio of the size of each structure is changed and shown in figure.

In addition, the above-mentioned polyvinyl alcohol-based film roll has a small deviation in winding hardness of 15 or less in durometer hardness as described above, and has almost no wrinkles or eccentricity. Therefore, when manufacturing a polarizing film, the polyvinyl alcohol-based film roll When the polyvinyl alcohol-based film 2 is pulled out, the polyvinyl alcohol-based film 2 has no wrinkles and can be pulled out uniformly. As a result, the obtained polarizing film is excellent in performance (the variation of the degree of polarization in the width direction is small, there is no color unevenness, etc.).

In more detail, in view of making the performance of the polarizing film produced more excellent, the winding hardness of the polyvinyl alcohol-based film roll is preferably in the range of 60 to 95 durometer hardness, particularly preferably 65 durometer hardness. Within the range of ～92, more preferably within the range of 70～90 durometer hardness. If the winding hardness is too high, the core tube 1 will be deformed or the polyvinyl alcohol-based film 2 will tend to be wrinkled in the winding step. If the winding hardness is too low, the portion of the polyvinyl alcohol-based film 2 located below the core tube 1 hangs down, and the roll of the polyvinyl alcohol-based film tends to be in an eccentric state. Moreover, since the extraction state of the polyvinyl-alcohol-type film 2 becomes non-uniform by this eccentricity, the polarizing film manufactured tends to generate|occur|produce color unevenness easily, and performance will deteriorate.

In addition, the deviation of the winding hardness in the width direction is, as mentioned above, a durometer hardness of 15 or less, preferably 12 or less, particularly preferably 10 or less, more preferably 8 or less. If the variation in winding hardness is too large, the polarizing film produced by using the polyvinyl alcohol-based film 2 of such a polyvinyl alcohol-based film roll as a forming material will have a large variation in the degree of polarization in the width direction and deteriorate performance.

[core tube] The above-mentioned core pipe 1 is generally cylindrical in shape. The material of the core pipe 1 includes, for example, aluminum, aluminum alloy, carbon, synthetic resin, etc., and these may be used alone or in combination of two or more. Among them, from the viewpoint of strength, aluminum alloy and carbon are suitable, and from the viewpoint of cost, aluminum alloy is usually used. In addition, the above-mentioned core tube 1 has an axial length of 3.5 m or more as described above, and is usually about 0 to 400 mm longer than the width of the polyvinyl alcohol-based film 2 wound on the core tube 1 . The diameter (outer diameter) of the above-mentioned cylindrical core tube 1 is usually in the range of 110-310 mm, and the wall thickness depends on the material of the core tube 1. When the material is aluminum alloy, it is usually 3-40 mm within the range.

[Polyvinyl alcohol film] The polyvinyl alcohol-based film 2 is generally formed into a long strip by continuous casting using a polyvinyl alcohol-based resin aqueous solution as a forming material. Manufactured by cutting off (cutting off). The width of the polyvinyl alcohol-based film 2 is, as described above, 3.5 m or more, preferably 4 m or more, particularly preferably 4.2 to 7.0 m, from the viewpoint of polarizing film production. That is, if the above-mentioned width is too large, it will be difficult to control the extraction of the above-mentioned polyvinyl alcohol-based film 2 when producing a polarizing film, and it will tend to be easily broken. When the said width is too narrow, it will tend to be difficult to manufacture the polarizing film corresponding to the enlargement of a liquid crystal display.

The length of the above-mentioned polyvinyl alcohol-based film 2 is, as mentioned above, 5000m or more, and it is preferably 10000m or more, particularly preferably 12000 to 30000m, from the viewpoint of handling and polarizing film productivity. That is, if the above-mentioned length is too long, the outer diameter and weight of the above-mentioned polyvinyl alcohol-based film roll will increase, so the equipment load will increase and the transport efficiency will tend to decrease. When the said length is too short, there exists a tendency for the productivity of a polarizing film to fall.

The thickness of the polyvinyl alcohol-based film 2 is, as described above, 60 μm or less, and it is preferably 55 μm or less from the viewpoint of production of a polarizing film. The lower limit of the thickness is preferably 10 μm. That is, if the above-mentioned thickness is too thick, the shrinkage force of the obtained polarizing film tends to become large, and it tends to be difficult to form the designed size. When the above-mentioned thickness is too thin, there is a tendency for breakage to easily occur during production of a polarizing film. The above thickness can be adjusted, for example, by adjusting the amount of the polyvinyl alcohol-based resin aqueous solution sprayed toward the casting drum in the above continuous casting method, or by adjusting the flow direction (MD) or width of the film 2 obtained by the spray film formation. The amount of stretching in the direction (TD) is carried out.

In view of making the performance of the polarizing film produced more excellent, the moisture content of the polyvinyl alcohol-based film 2 is preferably 5% by weight or less, particularly preferably in the range of 0.1 to 4% by weight, more preferably 0.2 to 3.5% by weight. within the range of weight %. If the above-mentioned moisture content is too high, the above-mentioned polyvinyl alcohol-based film 2 tends to stick easily, and if the above-mentioned moisture content is too low, the above-mentioned polyvinyl alcohol-based film 2 tends to be easily scratched. In any case, Both are likely to cause adverse effects on the performance of the polarizing film. The adjustment of the said moisture content can be performed by drying or humidity-conditioning the said polyvinyl-alcohol-type film 2 before winding, for example.

[Winding machine] Next, the winding machine used for manufacture of the said polyvinyl-alcohol-type film roll is demonstrated. As mentioned above, the winding machine is a machine for winding the obtained long polyvinyl alcohol-based film 2 to a designed width on the cylindrical core tube 1 .

That is, as shown in FIG. 2, the above-mentioned winding machine is provided with: a core tube support body 10 freely rotatably supporting the above-mentioned core tube 1, and a pair of control rollers 11, 12 arranged in parallel with the supported core tube 1 . In addition, the core tube support 10 is provided with a driving device (not shown in the figure) such as a motor for rotationally driving the core tube 1 . In addition, the winding machine winds the obtained polyvinyl alcohol-based film 2 around the core tube 1 while contacting at least one of the pair of control rollers 11 and 12, thereby manufacturing the polyvinyl alcohol-based film. roll. In addition, in FIG. 2 , reference numeral 5 is a guide roller provided in plurality (three in FIG. 2 ) so that the obtained elongated polyvinyl alcohol-based film 2 advances in the longitudinal direction to the above-mentioned winder. In addition, in FIG. 2, in order to make the structure of the said guide roller 5 and the winding machine easy to understand, the main part of each structure is shown schematically, and the ratio of the size of each main part (configuration) is changed and shown. The same applies to the subsequent FIG. 3 .

In this embodiment, the above-mentioned core tube support body 10 is in the shape of an arm, and the above-mentioned core tube 1 can be freely attached and detached at the front end of the arm. The imaginary plane of the axis can swing arbitrarily (refer to the arrow R in Figure 2). This oscillation is usually performed by a motor. The swing radius of the arm-shaped core tube support body 10 is larger than the radius of the produced polyvinyl alcohol-based film roll, and is usually in the range of 1.0 to 1.5 m.

The pair of control rolls 11 and 12 includes a first control roll 11 located on the side closer to the core tube 1 at the start of winding, and a second control roll 12 located on the far side. In this embodiment, the respective control rollers 11, 12 are rotatably attached to follow the front end portions of the respective swing arms 11a, 12a, and are arranged to face each other (arranged in a tandem type). Each swing arm 11a, 12a arbitrarily swings along an imaginary plane perpendicular to each control roller 11, 12 centering on the root portion. These swings are performed independently, and the above-mentioned pair of control rollers 11 and 12 can be independently adjusted in position. In addition, the above-mentioned swing is usually performed by a motor.

The material of each control roller 11, 12 is, for example, carbon steel, stainless steel, aluminum, aluminum alloy, carbon (carbon fiber), etc. From the viewpoint of bending due to tension, carbon (carbon fiber) is preferable. The size of each control roll 11, 12 is generally within the range of 100 to 300 mm in radius and 3.5 m or more in length, which is at least the width of the polyvinyl alcohol-based film 2 to be wound. The distance between the centers of the opposing control rollers 11 and 12 is usually in the range of 150 to 700 mm. The swing radius of the swing arms 11a, 12a is larger than that of the control rollers 11, 12, and is usually in the range of 200 to 1000 mm.

[Manufacturing method of polyvinyl alcohol-based film roll] Next, the manufacturing method of the said polyvinyl-alcohol-type film roll using the said winding machine is demonstrated.

That is, first, as shown in FIG. 2 , the core tube 1 is attached to and supported by the front end portion of the above-mentioned core tube support body 10 . Then, the above-mentioned core tube support body 10 is swung so that the entry angle α of the above-mentioned polyvinyl alcohol-based film 2 when the polyvinyl alcohol-based film 2 contacting the first control roller 11 starts to be wound around the outer peripheral surface of the above-mentioned core tube 1 In the range of 2° to 35°, the swing arm 11a on which the first control roller 11 is attached is swung to bring the core tube 1 close to the first control roller 11 . In this state, the position of the first control roller 11 is fixed (the swing arm 11a is not swung). In this approaching state, the gap (approximate amount) between the outer peripheral surface of the core pipe 1 and the outer peripheral surface of the first control roller 11 is preferably within a range of 2 to 5 mm.

Also, as will be described later, during winding, as the outer diameter of the polyvinyl alcohol-based film 2 wound on the core tube 1 increases, the core tube support 10 is made to swing, and the core tube 1 is gradually moved away from the above-mentioned core tube. When the first control roller 11 is in this manner, the entry angle α of the polyvinyl alcohol-based film 2 to be wound falls outside the above-mentioned range (2 to 35°) from a certain point of time. Therefore, as shown in FIG. 3 , in order to maintain the above-mentioned entry angle β within the above-mentioned range (2 to 35°), the polyvinyl alcohol-based film 2 should be brought into contact with the above-mentioned second control roller 12 from a predetermined point of time. , so that winding is performed without contacting the above-mentioned first control roller 11, and the position of the above-mentioned second control roller 12 is adjusted in advance and fixed (the swing arm 12a does not swing) before the winding starts.

In this way, the core tube 1 is rotated while the positions of the first control roll 11 and the second control roll 12 are fixed, and the polyvinyl alcohol-based film 2 starts to be wound around the outer peripheral surface of the core tube 1 .

From the beginning of winding until the above-mentioned predetermined time point (initial winding), as shown in FIG. Wound on the outer peripheral surface of the above-mentioned core pipe 1 . In this winding, as mentioned above, as the outer diameter of the polyvinyl alcohol-based film 2 wound on the core tube 1 increases, the core tube support 10 is made to swing (see arrow R in FIG. 2 ), and the core tube 1 Slowly move away from the above-mentioned first control roller 11.

If such winding is continued, as shown in FIG. 3 , from the above-mentioned predetermined time point, the above-mentioned polyvinyl alcohol-based film 2 will be far away from the above-mentioned first control roller 11 and no longer contact, and after contacting the above-mentioned second control roller 12, The winding is performed without contacting the above-mentioned first control roller 11 . The above-mentioned entry angle β in this winding is generally larger than the above-mentioned entry angle α at the initial stage of winding. Such winding is continued until the end of winding, and the above-mentioned polyvinyl alcohol-based film roll that is intended can be obtained.

The winding speed of the above-mentioned polyvinyl alcohol-based film 2 is preferably 35 m/min or more, particularly preferably 40 m/min, in view of making the shape of the cut surface after cutting and removing (cutting off) the ends on both sides become good. more than one minute, more preferably in the range of 50 to 150 m/minute. If the above-mentioned winding speed is too slow, the production efficiency tends to decrease, and if it is too fast, the shape of the cut surface after cutting and removing (cutting) the ends on both sides will deteriorate, which will adversely affect the performance of the polarizing film. Propensity.

In the above-mentioned winding, the angles α and β of the above-mentioned polyvinyl alcohol-based film 2 are between 2° and 35° in consideration of controlling the deviation of the winding hardness of the obtained polyvinyl alcohol-based film roll to a durometer hardness of 15 or less. Within the range, preferably within the range of 2-20°, particularly preferably within the range of 2-10°. If the entry angles α and β are too large, the portion of the polyvinyl alcohol-based film 2 located below the core tube 1 hangs down, and the roll of the polyvinyl alcohol-based film tends to be in an eccentric state. Moreover, since the extraction state of the polyvinyl-alcohol-type film 2 becomes non-uniform by this eccentricity, the polarizing film manufactured tends to generate|occur|produce color unevenness easily, and performance will deteriorate. If the entry angles α and β are too small, the polyvinyl alcohol-based film 2 tends to be easily wrinkled during winding.

In addition, in the above-mentioned winding, the outer peripheral surface of the above-mentioned polyvinyl alcohol-based film 2 and the above-mentioned first control roller 11 after taking into consideration the point of view that it is easy to maintain the above-mentioned entry angles α and β within the range of 2 to 35° are easily adjusted. The gap (approximate amount) between the outer peripheral surfaces should be maintained within the range of 2-10 mm, particularly preferably within the range of 2-8 mm, and more preferably within the range of 2-6 mm. Wherein, the gap is preferably maintained within the range of 2 to 5 mm at the initial stage of winding, and is preferably maintained at 6 mm or more after the initial stage of winding. If the gap is too large, the polyvinyl alcohol-based film roll tends to be in an eccentric state. Moreover, since the extraction state of the polyvinyl-alcohol-type film 2 becomes non-uniform by this eccentricity, the polarizing film manufactured tends to generate|occur|produce color unevenness easily, and performance will deteriorate. If the gap is too small, the polyvinyl alcohol-based film 2 tends to be easily wrinkled during winding.

In the production method of the above-mentioned polyvinyl alcohol-based film roll, the above-mentioned polyvinyl alcohol-based film 2 The winding tension should be maintained within the range of 100-300N/m, particularly preferably within the range of 120-280N/m, more preferably within the range of 140-260N/m. If the above-mentioned winding tension is too high, wrinkles due to winding tightening tend to easily occur. If the winding tension is too low, the portion of the polyvinyl alcohol-based film 2 located below the core tube 1 hangs down, and the roll of the polyvinyl alcohol-based film tends to be in an eccentric state. Moreover, since the extraction state of the polyvinyl-alcohol-type film 2 becomes non-uniform by this eccentricity, the polarizing film manufactured tends to generate|occur|produce color unevenness easily, and performance will deteriorate. Here, the above-mentioned winding tension is the tension applied per 1 m width of the polyvinyl alcohol-based film 2 to be wound. The adjustment of the winding tension can be applied to the above-mentioned polyvinyl alcohol-based film 2 by adjusting the rotation torque of the above-mentioned core tube 1 and the tension roll (tension roll) provided in the travel path of the above-mentioned polyvinyl alcohol-based film 2, for example. load etc.

In the manufacturing method of the above-mentioned polyvinyl alcohol-based film roll, the entry angles α, β of the polyvinyl alcohol-based film roll to be wound are maintained in the range of 2-35° by the pair of control rollers 11, 12. Thereby, the variation of the winding hardness of the polyvinyl alcohol-type film 2 in the width direction of the obtained said polyvinyl-alcohol-type film roll can be made into durometer hardness 15 or less. Thus, in the production method of the polyvinyl alcohol-based film roll, it is a major feature of the present invention to provide the pair of control rolls 11, 12 and maintain the entry angles α, β within the range of 2° to 35°.

In addition, in the manufacturing method of the above-mentioned polyvinyl alcohol-based film roll, the position of the pair of control rollers 11 and 12 can be adjusted independently, so the adjustment of the above-mentioned entry angles α and β has a high degree of freedom, and the polyvinyl alcohol-based film can be further optimized. The state of the roll (winding hardness, etc.).

The above-mentioned polyvinyl alcohol-based film roll produced in this way has little variation in winding hardness as described above, and almost no wrinkles or eccentricity, so the polyvinyl alcohol-based film 2 drawn out from the polyvinyl alcohol-based film roll has no Wrinkles, and can make it pull out evenly. Therefore, when a polarizing film is manufactured using the above-mentioned polyvinyl alcohol-based film 2 as a forming material, the polarizing film can be made excellent in performance such as no color unevenness.

[Polarizing film] The production of the above-mentioned polarizing film is usually carried out through steps such as swelling, dyeing, boric acid crosslinking, stretching, washing, and drying while running the above-mentioned polyvinyl alcohol-based film 2 along its longitudinal direction.

In addition, the obtained above-mentioned polarizing film can be formed into a polarizing plate by bonding an optically isotropic resin film as a protective film to one or both sides of the obtained polarizing film with an adhesive.

In addition, the above-mentioned polarizing film and polarizing plate can be ideally used in portable information terminals, personal computers, televisions, projectors, signboards, electronic desktop computers, electronic clocks, word processors, electronic paper, game machines, video recording Computers, cameras, photo albums, thermometers, audio, liquid crystal display devices such as automobiles or mechanical meters, sunglasses, anti-glare glasses, three-dimensional glasses, wearable displays, display elements (CRT, LCD, organic EL, electronic paper etc.) with anti-reflection layer, optical communication equipment, medical equipment, building materials, toys, etc.

In addition, in the above embodiment, the position adjustment of the pair of control rollers 11, 12 can be performed by swinging the swing arms 11a, 12a, and other methods are also possible, for example, the position adjustment can also be performed randomly. [Example]

Next, Examples and Comparative Examples will be described together. However, this invention is not limited to an Example.

[Example 1] Add 1,000kg of polyvinyl alcohol-based resin with a weight average molecular weight of 142,000 and a saponification degree of 99.8 mole%, 2,500kg of water, and 100kg of glycerin as a plasticizer into the dissolution tank, and raise the temperature to 140°C while stirring, and adjust the concentration to a resin concentration of 25 % by weight to obtain a homogeneously dissolved polyvinyl alcohol-based resin aqueous solution. Then, after supplying the polyvinyl alcohol-based resin aqueous solution to a twin-screw extruder and degassing, the temperature of the aqueous solution was set at 95°C, and it was sprayed and cast from the discharge port of a T-shaped slot die to a casting drum with a surface temperature of 90°C. Film making. Then, the formed film was dried with a plurality of metal heating rollers, and heat-treated using a floating dryer to form a polyvinyl alcohol-based film (continuous casting method). Then, using a cutting device, the end portions on both sides of the formed polyvinyl alcohol-based film roll were cut and removed (cut off) to a width of 4.5 m. In addition, using one of the above-mentioned winding machines in which the control rolls are arranged in a tandem type, the above-mentioned cut-off polyvinyl alcohol-based film with a length of 5000 m is wound on an aluminum alloy circle in the same manner as in the above-mentioned embodiment. The outer peripheral surface of the cylindrical core tube (diameter 230mm, wall thickness 15mm, axial length 4.8m). In this way, a polyvinyl alcohol-based film roll was obtained.

In this Example 1, the winding conditions were set as follows. ･Entering angle of polyvinyl alcohol-based film at the beginning of winding: 5°. ･The above entry angle from the start of winding to the end of winding: within the range of 5° to 10°. ･Gap (approach distance) between the outer peripheral surface of the wound polyvinyl alcohol-based film and the outer peripheral surface of the first control roll at the start of winding: 5 mm. ･Winding tension: 160N/m. ･Winding speed: 100m/min.

[Example 2] The width of the polyvinyl alcohol-based film formed by the continuous casting method in Example 1 was set to 5.0 m, and the length was set to 15500 m. Moreover, the width after cutting was set to 4.8m. In addition, the axial length of the cylindrical core tube was set to 5.0 m, the length of the polyvinyl alcohol-based film to be wound was set to 15000 m, and the winding tension was set to 200 N/m. Except for this, it carried out similarly to the said Example 1, and obtained the polyvinyl-alcohol-type film roll.

[Example 3] Using the continuous casting method in Example 1, a polyvinyl alcohol-based film with a moisture content of 1% by weight, a thickness of 45 μm, a width of 5.0 m, and a length of 17500 m was formed. Moreover, the width after cutting was set to 4.8m. In addition, the axial length of the cylindrical core tube is set to 5.0m, the length of the polyvinyl alcohol-based film to be wound is set to 17000m, the winding tension is set to 200N/m, and the winding speed is set to 70m/min . Except for this, it carried out similarly to the said Example 1, and obtained the polyvinyl-alcohol-type film roll.

[Comparative Example 1] Set the control roll of the winding machine among the embodiment 1 to 1. Also, in terms of winding conditions, the above-mentioned entry angle at the start of winding is set to 40°, the above-mentioned entry angle from the start of winding to the end of winding is set to 40-50°, the above-mentioned approach distance is set to 15 mm, and the winding The tension was set at 100 N/m, and the winding speed was set at 80 m/min. Except for this, it carried out similarly to the said Example 1, and obtained the polyvinyl-alcohol-type film roll.

>Winding hardness> The winding hardness measurement was performed about the roll of the polyvinyl-alcohol-type film of Examples 1-3 and Comparative Example 1 mentioned above. This measurement uses the Asker Hardness Tester JA type (manufactured by Polymer Meter Instruments Co., Ltd.), and the position 100 mm from the edge of the polyvinyl alcohol-based film roll in the width direction of the above-mentioned polyvinyl alcohol-based film is taken as the starting point. The width direction is carried out to the other end at intervals of 100mm. In addition, the average value of the measured hardness was defined as the above-mentioned winding hardness, and is shown in Table 1 below.

>Variation in winding hardness> The difference between the maximum value and the minimum value of the hardness measured above was defined as the deviation of the winding hardness, and is shown in Table 1 below.

>Appearance> The appearances of the polyvinyl alcohol-based film rolls of Examples 1 to 3 and Comparative Example 1 were visually observed, evaluated according to the following criteria, and are shown in Table 1 below. (evaluation criteria) 〇･･･There are almost no wrinkles or eccentricity, and the appearance is in good shape. ×･･･There are obvious wrinkles and eccentricity, and the appearance is poor.

[Table 1]

>Manufacture of Polarizing Film> The polyvinyl alcohol-based film was pulled out from the polyvinyl alcohol-based film rolls of Examples 1-3 and Comparative Example 1, immersed in a water tank with a water temperature of 25° C. to swell, and stretched to 1.7 times in the flow direction (MD). Then, it was dipped in an aqueous solution at 28° C. consisting of 0.5 g/L iodine and 30 g/L potassium iodide for dyeing, while stretching to 1.6 times in the flow direction (MD). Then, immerse in an aqueous solution (55° C.) composed of 40 g/L boric acid and 30 g/L potassium iodide to carry out boric acid cross-linking, while extending uniaxially to 2.1 times in the flow direction (MD). Finally, it was washed with an aqueous potassium iodide solution and dried to obtain a polarizing film with a total elongation ratio of 5.8 times.

>Polarization degree (%) and monomer transmittance (%)> A test piece with a length of 4 cm x a width of 4 cm was cut out from the central portion of the obtained polarizing film in the width direction, and the degree of polarization (%) and single transmittance ( %), and are shown in Table 2 below. In addition, the degree of polarization (%) shows an average value, a maximum value, and a minimum value.

>Stains> Cut out a test piece with a length of 30 cm x a width of 30 cm from the central part of the obtained polarizing film in the width direction, and clamp two polarizing plates (single transmittance 43.5 %, degree of polarization 99.9%), in this state, use a light box with a surface illumination of 14000 lx to observe the optical color spots in transmission mode, evaluate according to the following criteria, and are shown in Table 2 below. (evaluation criteria) 〇･･･No stains. △･･･Slightly stained. ×･･･There are obvious color spots.

[Table 2]

As can be seen from the results in Table 1 above, the polyvinyl alcohol-based film rolls of Examples 1 to 3 produced with little variation in winding hardness had excellent appearance (few wrinkles and eccentricity). In addition, from the results in Table 2 above, it can be seen that the polarizing film obtained by using the polyvinyl alcohol-based film drawn from such a polyvinyl alcohol-based film roll as a forming material has excellent performance (no color unevenness). In contrast, it can be seen that the polyvinyl alcohol-based film roll of Comparative Example 1 produced without considering the variation in winding hardness had poor appearance (wrinkles and eccentricity were observed). Furthermore, it was found that the performance of the polarizing film produced using the polyvinyl alcohol-based film drawn from such a polyvinyl alcohol-based film roll as a forming material was poor (stained).

In the above-mentioned examples, specific aspects of the present invention were shown, but the above-mentioned examples are only illustrative and should not be construed as limiting. Various modifications obvious to those skilled in the art are still intended to be included within the scope of the present invention. [Industrial Applicability]

The polyvinyl alcohol-based film roll and its manufacturing method according to the present invention can be used in rolls with excellent manufacturing performance without wrinkling or eccentricity even if the polyvinyl alcohol-based film wound on the core pipe is elongated and widened. Polarizing film.

1: core tube 2: Polyvinyl alcohol film 5: guide roller 10: Core tube support body 11: The first control roller 11a: arm swing 12: The second control roller 12a: arm swing α: entry angle β: Entry angle L: imaginary vertical line R: arrow

[ Fig. 1 ] is a perspective view schematically showing an embodiment of a polyvinyl alcohol-based film roll of the present invention. [ Fig. 2 ] is an explanatory view schematically showing an embodiment of one of the steps in the production method of the polyvinyl alcohol-based film roll of the present invention. [ Fig. 3 ] is an explanatory diagram schematically showing the steps following Fig. 2 .

1: core tube

2: Polyvinyl alcohol film

5: guide roller

10: Core tube support body

11: The first control roller

11a: arm swing

12: The second control roller

12a: arm swing

α: entry angle

L: imaginary vertical line

R: arrow

Claims (8)

A polyvinyl alcohol-based film roll comprising: a core tube with an axial length of 3.5 m or more; and polyethylene wound around the core tube for producing a polarizing film with a width of 3.5 m or more, a thickness of 60 μm or less, and a length of 5,000 m or more Alcohol-based film; it is characterized in that: the deviation of the winding hardness of the polyvinyl alcohol-based film in the width direction is less than 15 in the hardness of the durometer, and the measurement of the deviation of the winding hardness is carried out by the following method: using Polymer Meter Co., Ltd. Asker Hardness Tester JA type manufactured by the company, the above-mentioned polyvinyl alcohol-based film roll is 100 mm from one end edge of the width direction of the wound polyvinyl alcohol-based film as a starting point, and is carried out to the other end at an interval of 100 mm in the width direction. In the section, the average value of the measured hardness is defined as the above-mentioned winding hardness, and the difference between the maximum value and the minimum value of the above-mentioned measured hardness is defined as the deviation of the winding hardness. Such as the polyvinyl alcohol-based film roll of item 1 of the scope of the patent application, wherein the winding hardness falls within the range of 60-95 durometer hardness. The polyvinyl alcohol-based film roll as claimed in Claim 1 or 2, wherein the moisture content of the polyvinyl alcohol-based film is 5% by weight or less. A method for manufacturing a polyvinyl alcohol-based film roll, which is to rotate the core tube by arranging a first control roller and a second control roll parallel to the core tube in the vicinity of the core tube whose length in the axial direction is 3.5 m or more A polyvinyl alcohol-based film with a width of 3.5 m or more, a thickness of 60 μm or less, and a length of 5,000 m or more is wound around the core tube while contacting at least one of the first control roll and the second control roll , and get the The core tube, and the polyvinyl alcohol-based film roll wound on the core tube, such as the polyvinyl alcohol-based film roll of claim 1 or 2 of the scope of the patent application, is characterized in that: during winding, the roll rotates with the winding The outer diameter of the polyvinyl alcohol-based film of the core tube is increased, and the core tube is gradually moved away from the first control roller and the second control roller, wherein, until a predetermined time point during the period from the start of winding to the end of winding, The polyvinyl alcohol-based film is wound on the core tube while contacting the first control roll, and after the predetermined time point until the end of winding, the polyvinyl alcohol-based film is brought into contact with the second control roll without contacting the The first control roll is wound around the core tube so that the entry angle of the polyvinyl alcohol-based film is maintained within a range of 2° to 35° from the start of winding to the end of winding. Such as the manufacturing method of the polyvinyl alcohol-based film roll of claim 4, wherein the first control roll and the second control roll can be independently adjusted in position. For example, the manufacturing method of polyvinyl alcohol-based film roll in claim 4, wherein the winding tension of the polyvinyl alcohol-based film wound on the core tube is maintained within the range of 100-300 N/m. Such as the manufacturing method of the polyvinyl alcohol-based film roll of claim 4, wherein the gap between the outer peripheral surface of the polyvinyl alcohol-based film wound on the core tube and the outer peripheral surface of the first control roller is maintained at 2 Within the range of ~10mm. Such as the manufacturing method of polyvinyl alcohol-based film roll of claim 4, wherein the winding speed of the polyvinyl alcohol-based film is 35 m/min or more.

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