JPWO2020066883A1 - Film core and polyvinyl alcohol-based film roll using it - Google Patents

Abstract

In order to provide a film core capable of preventing unwinding and a polyvinyl alcohol-based film roll using the core, the core body 1 and a tape spirally attached to the outer peripheral surface of the core body 1. A film winding core for winding the film 5 provided with 2, wherein the spiral winding direction of the tape 2 is the first end side and the first end side from the axial center portion of the winding core main body 1. The direction is opposite to that of the end side of 2, so that a gap is provided between the adjacent tapes 2 in the tapes 2 attached in each spiral shape.

Description

The present invention relates to a film core for winding a film, and a polyvinyl alcohol-based film roll obtained by winding a polyvinyl alcohol-based film around the film core.

Generally, a film is produced in a long shape, then wound around a core to form a film roll, and stored or transported in the state of the film roll. Then, when the film is used, the film is unwound from the film roll.

If the film to be used has creases or wrinkles, the film cannot be used properly. Therefore, conventionally, a method has been proposed to prevent breakage and wrinkles when the film is wound around a winding core (see, for example, Patent Document 1). In this method, a double-sided tape (tape having adhesive layers on both sides) is spirally attached to the outer peripheral surface as the winding core, and a long shape to be wound around the adhesive portion on the surface of the double-sided tape. This is a method in which the tip of the film (one round at the beginning of winding) is attached and the film is wound in that state.

Japanese Unexamined Patent Publication No. 7-117904

However, in the winding method using the double-sided tape, one lap at the beginning of winding is attached to the double-sided tape and fixed. Therefore, if the one lap is not carefully wound, wrinkles are likely to occur. It has become. Therefore, it takes time and effort to wind up. Moreover, when wrinkles occur in one round, the wrinkles cannot be smoothed because they are fixed to the double-sided tape. Further, if the winding is continued with wrinkles in the first round of winding, the winding deviation is likely to occur. When the film to be wound is widened and lengthened, the tendency of unwinding to occur is remarkable.
Here, the "winding deviation" means that the positions of both side edges of the film are displaced in the axial direction of the winding core as the winding thickness increases.

For example, when the film is a polyvinyl alcohol-based film which is a material for forming a polarizing film, when the polarizing film is produced, the polyvinyl alcohol-based film is wound from a polyvinyl alcohol-based film roll wound around a winding core. , The polyvinyl alcohol-based film is unwound. If the polyvinyl alcohol-based film roll is unwound, the flow-out state of the polyvinyl alcohol-based film becomes non-uniform, or the polyvinyl alcohol-based film breaks. If the feeding state is non-uniform, the performance of the produced polarizing film becomes insufficient due to the non-uniformity, and when the breaking occurs, the production of the polarizing film is interrupted.

The present invention has been made in view of such circumstances, and provides a film core capable of preventing unwinding and a polyvinyl alcohol-based film roll using the same.

Based on the knowledge gained from the above-mentioned prior art, the present inventors have repeated research on the tape attached in a spiral shape in the winding core. In the process of the research, I came up with the idea of using a general tape having an adhesive layer on only one side instead of using the double-sided tape. Then, the spiral winding direction of the tape is set to be opposite to that of the first end side and the second end side from the central portion in the axial direction, and the tape attached in each spiral shape. A gap was provided between adjacent tapes. As a result, it was found that unwinding is prevented.
Further, even if the axial length of the winding core is 3 m or more, the polyvinyl alcohol-based film wound around the winding core is widened to a width of 3 m or more, and the length is 5000 m or more, winding misalignment occurs. I found out not to do it.

That is, the gist of the present invention is the following [1] to [7].
[1] A film core for winding a film, comprising a core body and a tape spirally attached to the outer peripheral surface of the core body.
The spiral winding direction of the tape is opposite between the first end side and the second end side from the axial center portion of the winding core body.
A film core in which a gap is provided between adjacent tapes in each spirally attached tape.
[2] The film according to the above [1], wherein the spirally attached state of the tape is plane-symmetric with respect to a surface perpendicular to the axis passing through the central portion in the axial direction of the core body. Winding core.
[3] The film core according to the above [1] or [2], wherein the angle of the spiral tape winding direction with respect to the axial direction of the core body is within the range of 20 to 70 °.
[4] The position of the end portion of the tape located at both ends of the core body is 10 to 10 on the central side in the axial direction from the planned position where both side edges of the film wound on the film core are located. The film core according to any one of the above [1] to [3], which is within the range of 300 mm.
[5] Above, at the center side in the axial direction from the planned position where both side edges of the film wound around the winding core for the film are located, and on both ends in the axial direction from the position of the end portion of the spiral tape. The film core according to the above [4], wherein the tape is attached in a ring shape separately from the spiral tape.
[6] The film core according to any one of [1] to [5] above, wherein the length in the axial direction is set to 3 m or more, and the width 3 m or more and the length wound around the core. A polyvinyl alcohol-based film roll comprising a polyvinyl alcohol-based film of 5000 m or more.
[7] The polyvinyl alcohol-based film roll according to the above [6], wherein the water content of the polyvinyl alcohol-based film is in the range of 0.1 to 4.0% by weight.

In the present invention, the "axial center portion" of the winding core body is a planned position where the center in the width direction of the film to be wound is located, and is not necessarily the axial center position of the winding core body. .. That is, the position deviated from the center position in the axial direction by 5% of the length of the winding core body is usually included in the "center portion in the axial direction".

The film core of the present invention has a tape spirally attached to the outer peripheral surface of the core body, and the spiral winding direction of the tape is from the axial center of the core body. The first end side and the second end side are in opposite directions, and a gap is provided between adjacent tapes in the tapes attached in each spiral shape.
Therefore, (1) when the film is wound around the core for the film, the end portion (one round) of the film at the beginning of winding is caught on the side surface (thick portion) of the tape. Therefore, an appropriate tension is generated at the end of the film at the beginning of winding, and wrinkles are less likely to occur. Further, (2) the portion of the film in contact with the tape rotates in the film core (with the winding of the film), and from the central portion in the axial direction to the first end side and the second end side in the axial direction. Move in opposite directions along. Moreover, (3) the tape is a general tape having an adhesive layer on only one side (not a double-sided tape), so that the portion of the film in contact with the tape is formed with the rotation of the film core (). With the winding of the film), moderate friction occurs and it slides moderately.
Combined with the actions of (1) to (3), wrinkles are less likely to occur at the end of the film at the beginning of winding, and even if wrinkles occur, the film core rotates with the rotation of the film (film). (With winding up), it is automatically stretched. Therefore, even if the film is continuously wound, it is possible to prevent the film from being unwound.

It is a top view which shows typically the 1st Embodiment of the winding core for a film of this invention. It is a top view which shows the way of winding a film around the winding core for a film. It is a top view which shows the other winding method. It is a top view which shows typically the 2nd Embodiment of the winding core for a film of this invention. It is a top view which shows typically the 3rd Embodiment of the winding core for a film of this invention.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

[Film core]
FIG. 1 is a plan view showing a first embodiment of a film core of the present invention. The film core includes a core body 1 and a tape 2 spirally attached to the outer peripheral surface of the core body 1. The spiral winding direction of the tape 2 is the first end side (left half in FIG. 1) and the second end side (right half in FIG. 1) from the axial center portion of the winding core body 1. And it's in the opposite direction. In this embodiment, one end (first end) 2a of the spiral tape 2 on both sides is in contact with the central portion in the axial direction, and the spirally attached state of the tape 2 is the shaft. It is plane symmetric with respect to a plane that passes through the center of the direction and is perpendicular to the axis. Further, a gap is provided between the adjacent tapes 2 in the tapes 2 attached in each spiral shape, and the outer peripheral surface of the winding core main body 1 is exposed from the gap. Such a winding method of the tape 2 is one of the major characteristic configurations of the present invention.
Due to its characteristic structure, the film 5 wound around the film core is prevented from being unwound.
In addition, in FIG. 1, in order to make it easy to understand the characteristics of the film core, each configuration is schematically shown and the scale of the size of each configuration is changed.

More specifically, the number of turns of each spiral tape 2 per 1 m of axial length of the core body 1 is usually more than 0 turns and 8 turns or less, from the viewpoint of further improving the prevention of unwinding. Therefore, it is preferable that the number of turns is 1 or more and 3 or less.
The area ratio of the attached tape 2 to the outer peripheral surface of the winding core body 1 is usually 1 to 10%, and is 1.5 to 5% from the viewpoint of further improving the prevention of unwinding. Is preferable.

Further, the angle (winding angle) θ of the winding direction of the spiral tape 2 with respect to the axial direction of the winding core body 1 shall be within the range of 20 to 70 ° from the viewpoint of further improving the prevention of winding misalignment. Is preferable, and particularly preferably 30 to 60 °.

Further, the spiral tapes 2 on both sides may be attached to both end edges of the winding core body 1, but if this is done, the spiral tapes 2 usually protrude from both end edges of the film 5 to be wound up, so that the appearance is good. bad. From the viewpoint of preventing unwinding, it is not necessary to attach the tape 2 to both end edges of the winding core body 1. That is, the positions of the other ends (second end portions) 2b of the spiral tape 2 on both sides, which are located at both ends of the winding core body 1, are the both side edges of the film 5 wound around the winding core for film. It is sufficient that the position is within a range of 10 to 300 mm (distance A shown in FIG. 1) on the central side in the axial direction from the planned position 5a where the is located. This distance A is preferably in the range of 0.15 to 10% of the width W of the film 5. In this way, not only the unwinding can be prevented, but also the appearance can be improved, and the waste of the tape 2 can be eliminated.

[Core body 1]
The winding core body 1 is formed in a cylindrical shape or a columnar shape. Examples of the material of the winding core body 1 include metal, synthetic resin, carbon, paper, and the like, which are selected according to the weight of the film 5 to be wound. The dimensions of the core body 1 are set according to the dimensions of the film 5 to be wound, for example, the axial length is within the range of 2 to 7 m, and the roundness is within the range of 0.01 to 1 mm. If the diameter (outer diameter) is within the range of 150 to 350 mm and the winding core body 1 is cylindrical, the wall thickness is set within the range of 3 to 40 mm. Further, when the winding core body 1 has a cylindrical shape, the inner diameter does not have to be constant, and for example, both ends in the axial direction may be smaller than the central portion.

In particular, when the film 5 to be wound is a polyvinyl alcohol-based film which is a material for forming a polarizing film, the core body 1 is made of the core body 1 in order to meet the recent demand for widening and lengthening of the polarizing film. The following are used. That is, the shape of the winding core main body 1 is cylindrical from the viewpoint of weight reduction. The material of the winding core body 1 is preferably an aluminum alloy or carbon from the viewpoint of strength, and usually an aluminum alloy is used from the viewpoint of cost.
In this case, the dimensions of the core body 1 are usually in the range of 3 m or more in the axial direction and 150 to 350 mm in diameter (outer diameter), and the wall thickness is the material of the core body 1. However, when the material is an aluminum alloy, it is within the range of 3 to 40 mm.

[Tape 2]
Further, the tape 2 may have any number of layers, but is a general tape 2 having an adhesive layer on only one side (back surface) and no adhesive layer on the other side (front surface) ( Not double-sided tape). Examples of the tape 2 include those in which the material of the surface layer (layer opposite to the adhesive layer) is synthetic resin, metal, carbon, paper, etc., and usually, from the viewpoint of cost, the surface layer is used. The material of the above is a synthetic resin, and among them, the material of the surface layer is polyvinyl chloride from the viewpoint of easy availability.
The width of the tape 2 is preferably in the range of 10 to 50 mm from the viewpoint of optimizing the number of turns of the tape 2 and the contact area with the film 5. The thickness of the tape 2 is in the range of 0.05 to 0.25 mm from the viewpoint of reducing the unevenness of the outer peripheral surface of the film core due to the tape 2 and making the film 5 properly caught. Is preferable.

Further, the adhesive force of the tape 2 to the core body 1 is preferably set to such that it can be peeled off by a human hand, and is preferably in the range of 0.5 to 5.0 N / cm, for example. ..
Further, from the viewpoint of optimizing the friction (slipperiness) between the surface of the tape 2 and the film 5 in contact with the surface and preventing wrinkles from being generated on the film 5 to be wound, the surface of the tape 2 The arithmetic average roughness (Ra) is preferably in the range of 0.05 to 0.20 μm, and the coefficient of static friction of the surface of the tape 2 with respect to the film 5 is in the range of 0.3 to 0.8. Is preferable.

The tape 2 is usually attached to the core body 1 by hand, but it may be attached by a dedicated machine.

〔the film〕
Examples of the film 5 to be wound include an acrylic film, a polyester film, a cellulose triacetate film, a cycloolefin polymer film, and the like, in addition to the polyvinyl alcohol-based film which is a material for forming a polarizing film described above.
The width of the film 5 is not particularly limited, but the effect of preventing the film 5 from being unwound by the film core is more exerted on the wide film 5. From this point of view, the width of the film 5 is preferably 1 m or more, for example. Further, from the viewpoint of improving the handleability, storability, transportability, etc. of the film roll obtained by winding the film 5 around the film core, the upper limit of the width of the film 5 is, for example, 7 m. Is preferable.
The length of the film 5 is not particularly limited, but it is preferably longer, for example, 50 m or more, from the viewpoint of increasing the productivity of the film 5 as a forming material. Further, from the viewpoint of improving the handleability of the film roll, the upper limit of the length of the film 5 is preferably, for example, 30,000 m.
The thickness of the film 5 varies depending on the intended use of the film 5, and is not particularly limited, but is, for example, in the range of 10 to 800 μm.

In particular, when the film 5 is a polyvinyl alcohol-based film which is a material for forming a polarizing film, the width of the polyvinyl alcohol-based film is usually increased in order to meet the recent demand for wider and longer polarizing films. The film has a width of 3 m or more and a length of 5000 m or more, preferably a film having a width of 4 m or more and a length of 10000 m or more, which is more effective in preventing unwinding. Further, as described above, from the viewpoint of improving the handleability of the polyvinyl alcohol-based film roll, the upper limit of the width is preferably 7 m and the upper limit of the length is preferably 30,000 m. Further, the thickness of the polyvinyl alcohol-based film roll is usually in the range of 15 to 65 μm from the viewpoint of improving the performance of the polarizing film to be produced.
The water content of the polyvinyl alcohol-based film is preferably in the range of 0.1 to 4.0% by weight, preferably 0.1 to 2.0, from the viewpoint of improving the performance of the polarizing film to be produced. The effect of preventing unwinding is more exhibited in the range of% by weight.
The water content of the polyvinyl alcohol-based film can be determined, for example, by the following formula.
Moisture content (%) = {(film weight before vacuum drying)-(film weight after vacuum drying)} x 100 / (film weight before vacuum drying)
-Film weight before vacuum drying: Weight of sample film.
-Film weight after vacuum drying: The weight of the sample film after vacuum drying the sample film in a vacuum dryer (vacuum degree: 10 mmHg or less) at 83 ° C. for 20 minutes.

[Rewinding of film 5]
Next, a method of winding the film 5 around the film core (a method of producing a film roll) will be described.

That is, first, the film core is rotatably supported by a winder (not shown). Then, the tip edge of the film 5 continuously produced in a long shape is fixed to the outer peripheral surface of the film core with a fixing tape (not shown) (see FIG. 2).
As the fixing tape, the same tape as the tape 2 which is spirally attached to the outer peripheral surface of the winding core main body 1 can be mentioned. The tape 2 spirally attached to the same winding core body 1 and the fixing tape may be the same or different.

Next, the film core is rotated, and the film 5 is wound around the film core. At this time, (1) the end portion (one round) of the film 5 at the start of winding is caught on the side surface (thick portion) of the tape 2. Therefore, an appropriate tension is generated at the end of the film 5 at the beginning of winding, and wrinkles are less likely to occur. Further, in this embodiment, as shown in the plan view of FIG. 2, (2) the portion of the film 5 in contact with the tape 2 is in the axial direction with the rotation of the film core (with the winding of the film 5). The film is wound so as to move from the center to both ends along. In FIG. 2, the arrow R indicates the rotation direction of the outer peripheral surface of the film core, and the arrow M indicates the traveling direction of the film 5. Moreover, (3) the tape 2 is a general tape 2 having an adhesive layer on only one side (not a double-sided tape), so that the portion of the film 5 in contact with the tape 2 is a film core. With the rotation of the film (with the winding of the film 5), a moderate amount of friction is generated and the film slides moderately.
Combined with the actions of (1) to (3), wrinkles are less likely to occur at the end of the film 5 at the beginning of winding, and even if wrinkles occur, the film core rotates with the rotation of the film core ( (Along with the winding of the film 5), it is automatically stretched. Therefore, even if the film 5 is continuously wound, it is possible to prevent the film 5 from being unwound.

In particular, in this embodiment, the spirally attached state of the tape 2 is symmetrical between the first end side and the second end side with the central portion in the axial direction of the winding core body 1 as the center. ing. Therefore, the winding state is symmetrical between the first end side and the second end side with the central portion of the film core in the axial direction as the center, so that the prevention of unwinding can be further improved.

In the first embodiment, when the film 5 is wound, as shown in FIG. 2, the portion of the film 5 in contact with the tape 2 is rotated with the rotation of the film core (with the winding of the film 5). ), It was moved from the center to both ends along the axial direction, but the reverse is also possible. That is, as shown in FIG. 3, the portion of the film 5 in contact with the tape 2 moves from both ends to the center along the axial direction with the rotation of the film core (with the winding of the film 5). In addition, the film 5 may be wound around a film core. In FIG. 3, the arrow R indicates the rotation direction of the outer peripheral surface of the film core, and the arrow M indicates the traveling direction of the film 5. Even in this way, it is possible to prevent winding misalignment. However, the winding direction shown in FIG. 2 is preferable from the viewpoint of further suppressing the occurrence of wrinkles during winding.

FIG. 4 is a plan view showing a second embodiment of the film core of the present invention. In the first embodiment shown in FIG. 1, the film core is in a state in which one end (first end) 2a of the spiral tape 2 on both sides is separated at the central portion in the axial direction. .. The distant distance B is usually set within a range of 1 to 20 cm (0.15 to 5.0% of the total length in the axial direction of the winding core body 1). Then, when the film 5 is wound, the center in the width direction of the film 5 to be wound (see FIG. 2) is located at the center position between the one end portions (first end portions) 2a of the tape 2 which are separated. Wind up as you do. The other parts are the same as those in the first embodiment, and the same parts are designated by the same reference numerals. The second embodiment also has the same action and effect as the first embodiment.

FIG. 5 is a plan view showing a third embodiment of the film core of the present invention. In the first embodiment shown in FIG. 1, the film core is axially centered on the planned position 5a where both side edges of the film 5 to be wound are located, and the spiral tape 2 is formed. In addition to the spiral tape 2, a ring-shaped tape 3 is attached to both ends in the axial direction from the position of the other end (second end) 2b at right angles to the axis. There is. Examples of the tape 3 attached in a ring shape include the same tape 3 as the tape 2 attached in a spiral shape. The tape 2 attached in a spiral shape and the tape 3 attached in a ring shape to the same winding core body 1 may be the same or different. The other parts are the same as those in the first embodiment, and the same parts are designated by the same reference numerals.

In the third embodiment, since the tape 3 is attached in a ring shape to the center side in the axial direction from the planned position 5a where both side edges of the film 5 to be wound are located, both sides of the film 5 at the start of winding are attached. The ring-shaped tape 3 prevents the edge from moving in the axial direction of the film core.
Therefore, in combination with the action of the spiral tape 2, it is possible to further prevent unwinding.

The fourth embodiment (not shown) of the film core of the present invention has a ring shape in the second embodiment shown in FIG. 4 in the same manner as the third embodiment shown in FIG. The tape 3 is attached. The fourth embodiment also has the same action and effect as the third embodiment.

In each of the above embodiments, the spiral tape 2 is attached to the film core with respect to the first end side and the second with respect to the plane passing through the central portion in the axial direction and perpendicular to the axis. Although it is plane-symmetrical with the end side of, it is not necessary to make it symmetrical as long as the winding misalignment can be prevented. That is, if the winding misalignment can be prevented, the material, width, number of turns, etc. of the spiral tape 2 may be different between the first end side and the second end side.

Further, in each of the above embodiments, when the film 5 to be wound is a polyvinyl alcohol-based film, a polyvinyl alcohol-based film roll can be produced, for example, as follows.
First, a polyvinyl alcohol-based resin aqueous solution is prepared using a polyvinyl alcohol-based resin, and this aqueous solution is discharged and cast in a casting mold, and a film is formed and dried by a casting method to continuously form a film. Manufacture a polyvinyl alcohol-based film.
Next, the polyvinyl alcohol-based film that is continuously produced can be produced as a polyvinyl alcohol-based film roll by using, for example, the following production method (α) or (β).
(Α) The film core of the present invention is wound into a roll while cutting and removing (slitting) both end portions of the continuously produced polyvinyl alcohol-based film.
(Β) While cutting and removing (slitting) both end portions of the continuously produced polyvinyl alcohol-based film, the film is once wound around a film core to obtain a temporary film roll. Then, the polyvinyl alcohol-based film wound from the temporary film roll is unwound, and the film core of the present invention is wound again while cutting and removing (slitting) both ends.

As described above, the core for film of the present invention can be used in any of the above-mentioned production methods (α) and (β), but it is produced from the viewpoint that the width of the polyvinyl alcohol-based film can be controlled more strictly. Method (β) is preferably used. In particular, in the manufacturing method (β), the film is unwound from a temporary film roll once the film is wound, and the end portion in the width direction is cut and removed (slit) to obtain a predetermined width, and the width is 50 m / min or more. It is preferably used because the effect of preventing unwinding of the film core of the present invention is remarkably exhibited when the film core of the present invention is wound at a high speed. This unwinding prevention effect is more remarkable when the film is wound around the film core of the present invention at a high speed of 60 m / min or more, and is more remarkable at 80 m / min or more.
Since the obtained polyvinyl alcohol-based film roll is prevented from being unwound, when the polyvinyl alcohol-based film is unwound from the polyvinyl alcohol-based film roll, the polyvinyl alcohol-based film is unwound without breaking. Can be made uniform. Therefore, when a polarizing film is produced using the polyvinyl alcohol-based film as a forming material, the polarizing film can be made excellent in performance such as no color unevenness.

The above-mentioned polarizing film can be used for personal digital assistants, personal computers, televisions, projectors, signage, electronic desk computers, electronic clocks, word processors, electronic paper, game machines, videos, cameras, photo albums, thermometers, audio, automobiles and machines. Liquid crystal displays such as instruments, sunglasses, anti-glare glasses, three-dimensional glasses, wearable displays, reflection reduction layers for display elements (CRT, LCD, organic EL, electronic paper, etc.), optical communication equipment, medical equipment, building materials , Preferably used for toys and the like.

Next, Examples will be described together with Comparative Examples. However, the present invention is not limited to the examples.

<Example 1>
[Film core]
As the winding core main body 1, a cylindrical one made of an aluminum alloy was prepared. The dimensions of the winding core body 1 were an axial length of 4.8 m, a roundness of 0.3 mm, a diameter (outer diameter) of 219 mm, and a wall thickness of 8 mm.
As the tape 2 to be attached to the outer peripheral surface of the winding core main body 1, a tape 2 having a width of 19 mm and a thickness of 0.2 mm (manufactured by Sekisui Chemical Co., Ltd.) having a surface layer made of polyvinyl chloride and an adhesive layer on the back surface. Eslon tape No. 360) was prepared.
Then, the tape 2 was attached to the outer peripheral surface of the winding core main body 1 in the same manner as in the first embodiment shown in FIG. At that time, the tape 2 was spirally attached with the angle (winding angle) θ of the winding direction of the tape 2 with respect to the axial direction of the winding core body 1 being 45 °. The positions of the ends 2b of the spiral tapes 2 on both sides, which are located at both ends of the winding core body 1, are in the axial direction from the planned positions 5a where both edges of the polyvinyl alcohol-based film to be wound are located. The position was 20 mm on the center side. As a result, each of the spiral tapes 2 on both sides has 2 turns per 1 m of axial length of the core body 1, a gap of 688 mm between adjacent tapes 2, and an outer peripheral surface of the core body 1. The area ratio of the attached tape 2 was 1.8%.

[Polyvinyl alcohol film roll]
As the film 5 to be wound around the film core, a polyvinyl alcohol-based film was prepared as described below and wound around the film core (continuous casting method).
That is, 1000 kg of polyvinyl alcohol-based resin having a weight average molecular weight of 142000 and a saponification degree of 99.8 mol%, 2500 kg of water, and 100 kg of glycerin as a plasticizing agent were placed in a dissolution can and heated to 140 ° C. with stirring to achieve a resin concentration of 25. The concentration was adjusted to% by weight to obtain a uniformly dissolved polyvinyl alcohol-based resin aqueous solution.
Then, the polyvinyl alcohol-based resin aqueous solution is supplied to a twin-screw extruder to defoam, and then the aqueous solution temperature is set to 95 ° C., and the aqueous solution is discharged and cast from a T-shaped slit die discharge port to a cast drum having a surface temperature of 90 ° C. And made a film.
Next, the film-formed film was dried with a plurality of metal heating rolls, heat-treated using a floating dryer, and then wound on a film roll while cutting and removing both end portions by 50 mm each to have a water content of 1. A temporary film roll was prepared in which a polyvinyl alcohol-based film having a thickness of 0.5% by weight, a thickness of 60 μm, and a width of 4.7 m was wound.
Subsequently, a polyvinyl alcohol-based film prepared to a width of 4.7 m was unwound from the temporary film roll, and both ends thereof were further cut and removed (slit) using a slit device to make the width 4.4 m. In the winding direction shown in FIG. 2, at a winding speed of 100 m / min, 12000 m was wound around the film core. In this way, a polyvinyl alcohol-based film roll was obtained. The appearance of the obtained polyvinyl alcohol-based film roll was evaluated according to the following criteria. The evaluation results are shown in Table 1 below.

(Appearance of polyvinyl alcohol-based film roll)
The amount of unwinding of the polyvinyl alcohol-based film roll was measured and evaluated according to the following criteria.
〇 (There is almost no unwinding): The amount of unwinding is less than 1 mm, and the edges of both ends of the film are aligned.
Δ (Slight winding deviation): The winding deviation amount is in the range of 1 to 5 mm.
X (large unwinding): The amount of unwinding exceeds 5 mm.

[Manufacturing of polarizing film]
From the obtained polyvinyl alcohol-based film roll, the polyvinyl alcohol-based film was unwound, run in the horizontal direction, immersed in a water tank having a water temperature of 30 ° C. and swollen, and stretched 1.7 times in the flow direction (MD). .. Then, it was immersed in an aqueous solution of iodine (0.5 g / L) and potassium iodide (potassium iodide) at 30 ° C. and dyed while being stretched 1.6 times in the flow direction (MD). Next, it was immersed in an aqueous solution (50 ° C.) having a composition of 40 g / L of boric acid and 30 g / L of potassium iodide, and uniaxially stretched 2.1 times in the flow direction (MD) while cross-linking with boric acid. Finally, the mixture was washed with an aqueous potassium iodide solution and dried at an atmospheric temperature of 50 ° C. for 2 minutes to obtain a polarizing film having a total draw ratio of 5.8 times.
During the production of the polarizing film using the entire amount (12000 m) of the polyvinyl alcohol-based film, the polyvinyl alcohol-based film was not broken.

<Example 2>
[Film core]
In the first embodiment, the axial length of the winding core main body 1 is set to 5 m, and the tapes 2 and 3 are applied to the outer peripheral surface of the winding core main body 1 in the same manner as in the third embodiment shown in FIG. , Spiral and ring-shaped. The position of the ring-shaped tape 3 was set to a position 50 mm on the central side in the axial direction from the planned position 5a where both side edges of the polyvinyl alcohol-based film to be wound are located. Further, the position of the end portion 5b of the spiral tape 2 on both sides is 55 mm (the position of the ring-shaped tape 3) on the central side in the axial direction from the planned position 5a where both side edges of the polyvinyl alcohol-based film to be wound are located. The position was 5 mm) on the central side in the axial direction. As a result, the area ratio of the attached tapes 2 and 3 to the outer peripheral surface of the winding core main body 1 was 2.2%. The other part of the winding core for the film was the same as in Example 1 above.

[Polyvinyl alcohol film roll]
In Example 1, the water content of the polyvinyl alcohol-based film was 1.0% by weight, the thickness was 45 μm, the width of the polyvinyl alcohol-based film after slitting was 4.7 m, and the winding length was 16000 m. The other parts for producing the polyvinyl alcohol-based film roll were the same as in Example 1 above. The appearance evaluation results of the obtained polyvinyl alcohol-based film roll are also shown in Table 1 below.

[Manufacturing of polarizing film]
From the obtained polyvinyl alcohol-based film roll, the polyvinyl alcohol-based film was unwound, run in the horizontal direction, immersed in a water tank having a water temperature of 30 ° C. and swollen, and stretched 1.7 times in the flow direction (MD). .. Then, it was immersed in an aqueous solution of iodine (0.5 g / L) and potassium iodide (potassium iodide) at 30 ° C. and dyed while being stretched 1.6 times in the flow direction (MD). Next, the mixture was immersed in an aqueous solution (50 ° C.) having a composition of 40 g / L of boric acid and 30 g / L of potassium iodide, and uniaxially stretched 2.0 times in the flow direction (MD) while cross-linking with boric acid. Finally, the mixture was washed with an aqueous potassium iodide solution and dried at an atmospheric temperature of 50 ° C. for 2 minutes to obtain a polarizing film having a total draw ratio of 5.6 times.
During the production of the polarizing film using the entire amount (16000 m) of the polyvinyl alcohol-based film, the polyvinyl alcohol-based film was not broken.

<Comparison example>
In the first embodiment, the tape is a double-sided tape having a width of 50 mm, and the tape is shafted from the planned position 5a where the central portion of the core body 1 in the axial direction and both side edges of the polyvinyl alcohol-based film to be wound are located. It was attached in a ring shape at a total of three locations, 20 mm on the center side of the direction. The other part of the winding core for the film was the same as in Example 1 above.
Then, the same polyvinyl alcohol-based film as in Example 1 was wound around the winding core for the film in the same manner as in Example 1 to prepare a polyvinyl alcohol-based film roll. The appearance evaluation results of the obtained polyvinyl alcohol-based film roll are also shown in Table 1 below.
A polyvinyl alcohol-based film was unwound from the above-mentioned polyvinyl alcohol-based film roll to produce a polarizing film in the same manner as in Example 1. However, the running polyvinyl alcohol-based film had a large meandering, frequent breakage, and a stable polarizing film. Could not be manufactured.

From the results in Table 1 above, it can be seen that in Examples 1 and 2, the types and winding methods of the tapes 2 and 3 in the film core are more effective in preventing unwinding as compared with the comparative examples.
Then, it can be seen that when the polyvinyl alcohol-based film is unwound from the polyvinyl alcohol-based film rolls of Examples 1 and 2 with almost no unwinding (the amount of unwinding is less than 1 mm) to produce a polarizing film, the production is stable.

Further, in Examples 1 and 2, even when the winding angles θ of the tape 2 were set to 20 ° and 70 °, the results showing the same tendency as those in Examples 1 and 2 were obtained.
Further, in Examples 1 and 2, the position of the end portion 2b of the tape 2 is set to a position of 10 mm and 300 mm on the central side in the axial direction from the planned position 5a where both side edges of the polyvinyl alcohol-based film to be wound are located. However, the results showing the same tendency as those of Examples 1 and 2 were obtained.

Although the specific embodiments of the present invention have been shown in the above examples, the above examples are merely examples and are not to be interpreted in a limited manner. Various variations apparent to those skilled in the art are intended to be within the scope of the present invention.

The film core of the present invention and the polyvinyl alcohol-based film roll using the same can be used to prevent unwinding.

1 Core body 2 Tape 5 Film

Claims (7)

A film core for winding a film, which comprises a core body and a tape spirally attached to the outer peripheral surface of the core body.
The spiral winding direction of the tape is opposite between the first end side and the second end side from the axial center portion of the winding core body.
A winding core for a film, characterized in that a gap is provided between adjacent tapes in the tapes attached in a spiral shape. The film core according to claim 1, wherein the spirally attached state of the tape passes through the central portion in the axial direction of the core body and is plane-symmetric with respect to a surface perpendicular to the axis. The film core according to claim 1 or 2, wherein the angle of the spiral tape winding direction with respect to the axial direction of the core body is within the range of 20 to 70 °. The position of the end of the tape located at both ends of the core body is in the range of 10 to 300 mm on the central side in the axial direction from the planned position where both edges of the film wound on the film core are located. The film core according to any one of claims 1 to 3. The spiral shape is located on the center side in the axial direction from the planned position where both side edges of the film wound around the film core are located, and on both ends in the axial direction from the position of the end portion of the spiral tape. The film core according to claim 4, wherein the tape is attached in a ring shape separately from the tape. The film core according to any one of claims 1 to 5 having an axial length of 3 m or more, and a winding core having a width of 3 m or more and a length of 5000 m or more. A polyvinyl alcohol-based film roll comprising a polyvinyl alcohol-based film. The polyvinyl alcohol-based film roll according to claim 6, wherein the water content of the polyvinyl alcohol-based film is in the range of 0.1 to 4.0% by weight.

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