JP7247891B2 - Film winding core and polyvinyl alcohol film roll using the same - Google Patents

Description

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

In general, a film is manufactured in a long shape, wound around a winding core to form a film roll, and stored or transported in the state of the film roll. When using the film, the film is unwound from the film roll.

If the film to be used has folds or wrinkles, it cannot be used properly. Therefore, conventionally, a method has been proposed to prevent the film from being bent or wrinkled when the film is wound around the core (see, for example, Patent Document 1). In this method, as the winding core, a double-sided tape (a tape having an adhesive layer on both sides) is spirally attached to the outer peripheral surface, and the adhesive part on the surface of the double-sided tape is used. , the tip of the film (one turn at the start of winding) is attached, and the film is wound in that state.

JP-A-7-117904

However, in the winding method using the double-sided tape, the first round of winding is attached to the double-sided tape and fixed. It's becoming Therefore, winding requires time and effort. Moreover, when wrinkles are generated in one round, the wrinkles cannot be smoothed out because they are fixed to the double-sided tape. Further, if the winding is continued in a state in which there is a wrinkle in one turn at the start of winding, winding deviation is likely to occur. When the film to be wound up is widened and elongated, there is a marked tendency for winding misalignment to occur.
Here, the "winding deviation" means that as the winding thickness increases, the positions of both side edges of the film are shifted in the axial direction of the core.

For example, when the film is a polyvinyl alcohol-based film that is a material for forming a polarizing film, when producing the polarizing film, the polyvinyl alcohol-based film is wound around a core from a polyvinyl alcohol-based film roll. , the polyvinyl alcohol-based film is paid out. If the polyvinyl alcohol-based film roll has a winding misalignment, the polyvinyl alcohol-based film may be unrolled unevenly or the polyvinyl alcohol-based film may be broken. If the extension state is uneven, the performance of the manufactured polarizing film will be insufficient, and if the breakage occurs, the manufacturing of the polarizing film will be interrupted.

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

The inventors of the present invention conducted extensive research on the spirally attached tape on the winding core based on the findings obtained from the above-mentioned prior art. In the course of the research, it was conceived to use a general tape having an adhesive layer only on one side instead of using the above double-sided tape as the tape. Then, the helical winding direction of the tape is opposite to the first end side and the second end side from the axial center part, and each helically attached tape A gap was provided between adjacent tapes. As a result, the inventors have found that winding misalignment can be prevented.
Further, even if the length of the core in the axial direction is 3 m or more, and the polyvinyl alcohol film wound around the core is widened to a width of 3 m or more and has a length of 5000 m or more, winding misalignment occurs. I figured out what not to do.

That is, the gist of the present invention is the following [1] to [7].
[1] A film winding core for winding a film, comprising a winding core body and a tape spirally attached to the outer peripheral surface of the winding core body,
The helical winding direction of the tape is opposite to the first end side and the second end side from the axial center of the core body,
A film core in which a gap is provided between adjacent tapes in each spirally adhered tape.
[2] The film according to [1] above, wherein the tape is helically attached in a symmetrical manner with respect to a plane passing through the center of the core body in the axial direction and perpendicular to the axis. winding core.
[3] The film core according to [1] or [2] above, wherein the angle of the winding direction of the spiral tape with respect to the axial direction of the core body is in the range of 20 to 70°.
[4] Positions of the ends of the tape located at both ends of the core body are 10 to 10 to the center in the axial direction from the planned positions where both side edges of the film to be wound on the film core are positioned. The film winding core according to any one of the above [1] to [3], which is within the range of 300 mm.
[5] The film is wound on the film core on the center side in the axial direction from the planned positions where both side edges of the film are located, and on both axial side sides from the end positions of the spiral tape. The film winding core according to [4] above, in which a 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 film wound on the core having a width of 3 m or more and a length of 3 m or more. A polyvinyl alcohol film roll comprising a polyvinyl alcohol film of 5000 m or more.
[7] The polyvinyl alcohol film roll of [6] above, wherein the polyvinyl alcohol film has a water content of 0.1 to 4.0% by weight.

In the present invention, the "axial center portion" of the core body is a planned position where the center of the film to be wound in the width direction is located, and is not necessarily the center position of the core body in the axial direction. . In other words, the "axial center portion" generally includes a position shifted by 5% of the length of the core body from the axial center position.

In the film core of the present invention, a tape is helically adhered to the outer peripheral surface of the core body, and the helical winding direction of the tape extends 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 each spirally attached tape.
Therefore, (1) when the film is wound around the film core, the end (one turn) of the film at the start of winding is caught on the side surface (thickness portion) of the tape. Therefore, a moderate tension is generated at the end of the film at the start of winding, and wrinkles are less likely to occur. In addition, (2) the portion of the film in contact with the tape moves along the rotation of the film core (along with the winding of the film) to the first end side and the second end side from the axial center portion in the axial direction. move in opposite directions along the In addition, (3) the tape is a general tape having an adhesive layer only on one side (not a double-sided tape), so the portion of the film that contacts the tape moves along with the rotation of the film core ( film winding), moderate friction occurs and moderate slippage.
Together, these actions (1) to (3) make it difficult for wrinkles to occur at the end of the film at the start of winding. (together with the winding of the tape), it is automatically stretched. Therefore, even if the film continues to be wound, it is possible to make it difficult for winding misalignment to occur.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view schematically showing a first embodiment of a film winding core of the present invention; FIG. 4 is a plan view showing how to wind the film around the film winding core. It is a top view which shows another winding method. FIG. 4 is a plan view schematically showing a second embodiment of the film winding core of the present invention. FIG. 3 is a plan view schematically showing a third embodiment of the film winding core of the present invention.

An embodiment of the present invention will now be described in detail with reference to the drawings.

[Film winding core]
FIG. 1 is a plan view showing a first embodiment of the film winding core of the present invention. This film core comprises 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 from the axial center of the core body 1 to the first end side (left half in FIG. 1) and the second end side (right half in FIG. 1). and in the opposite direction. In this embodiment, one ends (first ends) 2a of the spiral tapes 2 on both sides are in contact with each other at the central portion in the axial direction. It has plane symmetry with respect to a plane that passes through the center of the direction and is perpendicular to the axis. Further, gaps are provided between adjacent tapes 2 in each spirally attached tape 2, and the outer peripheral surface of the winding core body 1 is exposed through the gaps. The method of winding the tape 2 in this manner is one of the major characteristic features of the present invention.
This characteristic structure prevents the film 5 wound around the film core from being displaced.
In FIG. 1, in order to make the characteristics of the film core easy to understand, each configuration is shown schematically, and each configuration is illustrated with different scales.

More specifically, the number of turns of each helical tape 2 per 1 m of the 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 winding slippage. Therefore, it is preferable that the number of turns is 1 or more and 3 or less.
The area ratio of the adhered tape 2 to the outer peripheral surface of the core body 1 is usually 1 to 10%, and from the viewpoint of further improving the prevention of winding deviation, it is 1.5 to 5%. is preferred.

In addition, 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 is in the range of 20 to 70° from the viewpoint of further improving the prevention of winding slippage. is preferred, and 30 to 60° is particularly preferred.

Furthermore, the helical tapes 2 on both sides may be adhered to both edges of the winding core body 1. However, in such a case, the film 5 is normally wound out of both edges, resulting in poor appearance. bad. From the point of view of preventing winding slippage, it is not necessary to adhere the tape 2 to both end edges of the core body 1 . That is, the positions of the other ends (second ends) 2b of the helical tapes 2 on both sides located at both ends of the core body 1 correspond to both side edges of the film 5 wound around the film core. It is sufficient to be within a range of 10 to 300 mm (distance A shown in FIG. 1) toward the center in the axial direction from the planned position 5a where the . This distance A is preferably within the range of 0.15 to 10% of the width W of the film 5 . By doing so, it is possible not only to prevent winding slippage, but also to improve the appearance of the tape 2 and to eliminate waste of the tape 2. - 特許庁

[Core body 1]
The winding core body 1 is formed in a cylindrical or columnar shape. Examples of the material of the core body 1 include metal, synthetic resin, carbon, paper, etc., and the material is selected according to the weight of the film 5 to be wound. The dimensions of the winding core body 1 are set according to the dimensions of the film 5 to be wound, and the like. The diameter (outer diameter) is set within the range of 150 to 350 mm, and if the winding core body 1 is cylindrical, the wall thickness is set within the range of 3 to 40 mm. Further, when the core body 1 is cylindrical, the inner diameter may not 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 that is a material for forming a polarizing film, in order to meet the recent demands for wider and longer polarizing films, the core body 1 is The following are used. That is, the shape of the winding core body 1 is cylindrical from the viewpoint of weight reduction. The material of the 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 core body 1 generally has an axial length of 3 m or more and a diameter (outer diameter) of 150 to 350 mm. However, if the material is an aluminum alloy, it is within the range of 3 to 40 mm.

[Tape 2]
In addition, although the tape 2 may have any number of layers, it is a general tape 2 that has an adhesive layer only on one side (back surface) and does not have an adhesive layer on the other side (front surface) ( not double sided tape). As the tape 2, the material of the surface layer (the layer on the side opposite to the adhesive layer) is, for example, synthetic resin, metal, carbon, paper, or the like. The material of the surface layer is a synthetic resin, and from the viewpoint of easy availability, the material of the surface layer is polyvinyl chloride.
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 making the tape 2 less uneven on the outer peripheral surface of the film core and optimizing the degree of hooking of the film 5. is preferred.

Furthermore, the adhesive force of the tape 2 to the winding core body 1 is preferably set to the extent that it can be peeled off by hand, for example, preferably within the range of 0.5 to 5.0 N/cm. .
In addition, 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 occurring in the film 5 to be wound, the surface of the tape 2 is The arithmetic mean roughness (Ra) is preferably in the range of 0.05 to 0.20 μm, and the static friction coefficient of the surface of the tape 2 with respect to the film 5 is in the range of 0.3 to 0.8 is preferably

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

〔the film〕
Examples of the film 5 to be wound include acrylic film, polyester film, cellulose triacetate film, cycloolefin polymer film, etc., in addition to the polyvinyl alcohol film which is the material for forming the polarizing film.
The width of the film 5 is not particularly limited. From this point of view, the width of the film 5 is preferably 1 m or more, for example. In addition, from the viewpoint of improving the handling, storage, 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 preferred.
The length of the film 5 is not particularly limited, but from the viewpoint of increasing the productivity of those using the film 5 as a forming material, it is preferably longer, for example, 50 m or longer. Moreover, from the viewpoint of improving the handleability of the film roll, the upper limit of the length of the film 5 is preferably 30000 m, for example.
The thickness of the film 5 varies depending on the application 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 that is a material for forming a polarizing film, the width of the polyvinyl alcohol-based film is usually is 3 m or longer, and the length is 5,000 m or longer. Preferably, a film having a width of 4 m or longer and a length of 10,000 m or longer exhibits the effect of preventing winding shift. As in the above case, from the viewpoint of improving the handleability of the polyvinyl alcohol film roll, the upper limit of the width is preferably 7 m, and the upper limit of the length is preferably 30000 m. Furthermore, the thickness of the polyvinyl alcohol-based film roll is usually within the range of 15 to 65 μm from the viewpoint of improving the performance of the produced polarizing film.
The water content of the polyvinyl alcohol film is preferably in the range of 0.1 to 4.0% by weight, more preferably 0.1 to 2.0, from the viewpoint of improving the performance of the polarizing film to be produced. In the range of % by weight, the effect of preventing winding shift is exhibited.
The water content of the polyvinyl alcohol film can be determined, for example, by the following formula.
Moisture content (%) = {(film weight before drying under reduced pressure) - (film weight after drying under reduced pressure)} x 100/(film weight before drying under reduced pressure)
- Film weight before drying under reduced pressure: the weight of the sample film.
- Film weight after drying under reduced pressure: Weight of the sample film after drying under reduced pressure for 20 minutes at 83°C in a vacuum dryer (degree of vacuum: 10 mmHg or less).

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

First, the film core is rotatably supported by a winder (not shown). Next, the leading edge of the film 5, which is 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 spirally adhered to the outer peripheral surface of the winding core body 1 can be used. 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 (one turn) of the film 5 at the start of winding is caught on the side surface (thickness portion) of the tape 2 . Therefore, a suitable tension is generated at the end of the film 5 at the start 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 moves axially as the film core rotates (as the film 5 is wound up). The film is wound so as to move from the center to both ends along the . In FIG. 2, arrow R indicates the direction of rotation of the outer peripheral surface of the film core, and arrow M indicates the running direction of the film 5. As shown in FIG. Moreover, (3) since the tape 2 is a general tape 2 having an adhesive layer only on one side (not a double-sided tape), the portion of the film 5 that contacts the tape 2 is a film winding core. With the rotation of (with the winding of the film 5), moderate friction is generated and moderate slippage occurs.
Together, these actions (1) to (3) make it difficult for wrinkles to occur at the end of the film 5 at the start of winding. (together with winding of the film 5), it is automatically stretched. Therefore, even if the film 5 continues to be wound, it is possible to make it difficult for winding misalignment to occur.

In particular, in this embodiment, the tape 2 is adhered in a helical manner so that the first end side and the second end side are symmetrical about the central portion of the core body 1 in the axial direction. ing. Therefore, since the winding state is symmetrical between the first end side and the second end side about the axially central portion of the film core, it is possible to further improve the prevention of winding slippage.

In the first embodiment, when winding the film 5, as shown in FIG. ), and moved along the axial direction from the central portion to both end sides, but the opposite is also possible. That is, as shown in FIG. 3, the portion of the film 5 in contact with the tape 2 moves along the axial direction from both end sides to the central portion as the film core rotates (as the film 5 is wound up). Alternatively, the film 5 may be wound around a film core. In FIG. 3, arrow R indicates the direction of rotation of the outer peripheral surface of the film core, and arrow M indicates the running direction of the film 5. As shown in FIG. In this way, it is also possible to prevent winding misalignment. However, the winding direction shown in FIG. 2 is preferable from the viewpoint of being able to further suppress the occurrence of wrinkles during winding.

FIG. 4 is a plan view showing a second embodiment of the film winding core of the present invention. In the first embodiment shown in FIG. 1, this film core has one end (first end) 2a of the spiral tape 2 on both sides separated at the center in the axial direction. . The distance B is usually set within a range of 1 to 20 cm (0.15 to 5.0% of the total length of the core body 1 in the axial direction). When winding the film 5, the widthwise center of the film 5 (see FIG. 2) to be wound is positioned at the center position between the separated ends (first ends) 2a of the tape 2. wind it up. Other parts are the same as those of the first embodiment, and the same reference numerals are given to the same parts. And this 2nd Embodiment also produces|plays the effect|action and effect similar to the said 1st 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, this film winding core is located on the axial center side of the predetermined position 5a where both side edges of the film 5 to be wound are located, and is located on the spiral tape 2. Separately from the spiral tape 2, a loop of tape 3 is attached perpendicularly to the axis on both ends in the axial direction from the position of the other end (second end) 2b. there is The tape 3 attached in a ring shape may be the same as the tape 2 attached in a spiral shape. The tape 2 helically attached to the same winding core body 1 and the tape 3 attached in a loop may be the same or different. Other parts are the same as those of the first embodiment, and the same reference numerals are given to the same parts.

In this third embodiment, since the tape 3 is attached in a ring shape to the center side in the axial direction of the predetermined positions 5a where the both side edges of the film 5 to be wound are positioned, both sides of the film 5 at the start of winding The annular 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 winding misalignment.

A fourth embodiment (not shown) of the film winding core of the present invention is similar to the third embodiment shown in FIG. 5 in the second embodiment shown in FIG. A tape 3 is attached. And this 4th Embodiment also produces|plays the effect|action and effect similar to the said 3rd Embodiment.

In each of the above-described embodiments, the spiral tape 2 is adhered to the film core with respect to a plane passing through the central portion in the axial direction and perpendicular to the axis. However, it is not necessary to be symmetrical as long as it is possible to prevent winding misalignment. That is, 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, as long as the winding shift can be prevented.

Moreover, in each of the above embodiments, when the film 5 to be wound is a polyvinyl alcohol film, a polyvinyl alcohol 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, the aqueous solution is discharged and cast into a casting mold, and a film is formed by a casting method and dried continuously. A polyvinyl alcohol film is manufactured.
Next, the continuously produced polyvinyl alcohol film can be used to produce a polyvinyl alcohol film roll, for example, by using the following production method (α) or (β).
(α) While cutting off (slitting) both side end portions of the continuously produced polyvinyl alcohol film, it is wound into a roll around the film winding core of the present invention.
(β) While cutting off (slitting) both side ends of the continuously produced polyvinyl alcohol-based film, the film is temporarily wound into a roll on a film winding core to obtain a temporary film roll. Thereafter, the polyvinyl alcohol-based film wound up from the temporary film roll is unwound and wound up again around the film core of the present invention while cutting off (slitting) both ends.

As described above, the film winding core of the present invention can be used in any of the production methods (α) and (β) above. Method (β) is preferably used. In particular, in the production method (β), the film is unwound from a temporary film roll on which the film is once wound, and the widthwise end is cut off (slit) to a predetermined width, while the speed is 50 m or more per minute. When the film winding core of the present invention is wound at a high speed, the film winding core of the present invention is preferably used because the effect of preventing the winding deviation of the film core of the present invention is exhibited remarkably. This effect of preventing winding slippage is remarkably exhibited when the film is wound on the film core of the present invention at a high speed of 60 m/min or more, and is further remarkably exhibited at 80 m/min or more.
Since the obtained polyvinyl alcohol-based film roll is prevented from winding misalignment, when the polyvinyl alcohol-based film is paid out from the polyvinyl alcohol-based film roll, the polyvinyl alcohol-based film is not broken. 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 to have excellent performance such as no color unevenness.

The polarizing film can be used for personal digital assistants, personal computers, televisions, projectors, signage, electronic desk calculators, electronic clocks, word processors, electronic paper, game machines, videos, cameras, photo albums, thermometers, audio equipment, automobiles and machinery. Liquid crystal display devices such as instruments, sunglasses, anti-glare glasses, stereoscopic glasses, wearable displays, reflection reduction layers for display elements (CRT, LCD, organic EL, electronic paper, etc.), optical communication equipment, medical equipment, building materials , 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 winding core]
As the winding core main body 1, a cylindrical one made of an aluminum alloy was prepared. The core body 1 had an axial length of 4.8 m, a circularity 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 body 1, the surface layer is made of polyvinyl chloride, and the tape 2 having a width of 19 mm and a thickness of 0.2 mm having an adhesive layer on the back surface (manufactured by Sekisui Chemical Co., Ltd., Eslon Tape No. 360) was prepared.
Then, the tape 2 was adhered to the outer peripheral surface of the winding core body 1 in the same manner as in the first embodiment shown in FIG. At that time, the winding direction angle (winding angle) .theta. The positions of the ends 2b of the spiral tape 2 on both sides, which are positioned at both ends of the winding core body 1, are further axially than the planned positions 5a where both side edges of the polyvinyl alcohol film to be wound are positioned. The position was 20 mm on the center side. As a result, each of the spiral tapes 2 on both sides has a number of turns of 2 per 1 m of the axial length of the core body 1, a gap between adjacent tapes 2 of 688 mm, and an outer peripheral surface of the core body 1. The area ratio occupied by the adhered 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 produced in the following manner and wound around the film core (continuous casting method).
That is, 1000 kg of a polyvinyl alcohol resin having a weight average molecular weight of 142000 and a degree of saponification of 99.8 mol%, 2500 kg of water, and 100 kg of glycerin as a plasticizer are placed in a dissolving can, heated to 140°C with stirring, and the resin concentration is 25. The concentration was adjusted to % by weight, and a uniformly dissolved polyvinyl alcohol resin aqueous solution was obtained.
Next, the polyvinyl alcohol-based resin aqueous solution is supplied to a twin-screw extruder and defoamed, then the temperature of the aqueous solution is set to 95 ° C., and it is discharged from the T-shaped slit die outlet to a cast drum with a surface temperature of 90 ° C. and cast. and formed a film.
Next, the formed film is dried with a plurality of metal heating rolls, subjected to heat treatment using a floating dryer, and then wound up on a film roll while cutting and removing 50 mm of both side ends to obtain a moisture content of 1. A temporary film roll was prepared by winding a polyvinyl alcohol-based film of .5% by weight, 60 μm in thickness and 4.7 m in width.
Subsequently, a polyvinyl alcohol film prepared to a width of 4.7 m was unwound from the temporary film roll, and its both ends were further cut and removed (slit) using a slitting device to make the width 4.4 m, In the winding direction shown in FIG. 2, 12,000 m of the film was wound on the film core at a winding speed of 100 m/min. Thus, a polyvinyl alcohol film roll was obtained. The appearance of the obtained polyvinyl alcohol film roll was evaluated according to the following criteria. Evaluation results are shown in Table 1 below.

(Appearance of polyvinyl alcohol film roll)
With respect to the polyvinyl alcohol-based film roll, the winding misalignment amount was measured and evaluated according to the following criteria.
◯ (almost no winding deviation): The amount of winding deviation is less than 1 mm, and both edges of the film are aligned.
Δ (slight misalignment): The amount of misalignment is in the range of 1 to 5 mm.
x (large winding deviation): winding deviation exceeds 5 mm.

[Manufacture of polarizing film]
A polyvinyl alcohol-based film was unwound from the polyvinyl alcohol-based film roll obtained above, and while running in the horizontal direction, it was immersed in a water tank at a water temperature of 30°C to swell and stretched 1.7 times in the machine direction (MD). . Then, the film was immersed in an aqueous solution containing 0.5 g/L of iodine and 30 g/L of potassium iodide at 30° C. and stretched 1.6 times in the machine direction (MD) while being dyed. Next, the film was immersed in an aqueous solution (50° C.) containing 40 g/L of boric acid and 30 g/L of potassium iodide and uniaxially stretched 2.1 times in the machine direction (MD) while cross-linking with boric acid. Finally, the film was washed with an aqueous solution of potassium iodide and dried at an atmospheric temperature of 50° C. for 2 minutes to obtain a polarizing film with a total draw ratio of 5.8.
During the production of the polarizing film using the entire polyvinyl alcohol film (12,000 m), the polyvinyl alcohol film was not broken.

<Example 2>
[Film winding core]
In Example 1, the axial length of the core body 1 is set to 5 m, and the tapes 2 and 3 are applied to the outer peripheral surface of the core body 1 in the same manner as in the third embodiment shown in FIG. , spirally and annularly. The position of the ring-shaped tape 3 was set at a position 50 mm toward the center in the axial direction from the planned position 5a where both side edges of the polyvinyl alcohol film to be wound are positioned. In addition, the positions of the ends 5b of the spiral tape 2 on both sides are 55 mm (the position of the ring-shaped tape 3) toward the center in the axial direction from the planned position 5a where both side edges of the polyvinyl alcohol film to be wound are located. 5 mm) on the center side in the axial direction. As a result, the area ratio of the adhered tapes 2 and 3 to the outer peripheral surface of the core body 1 was 2.2%. Other portions of the film winding core were the same as in Example 1 above.

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

[Manufacture of polarizing film]
A polyvinyl alcohol-based film was unwound from the polyvinyl alcohol-based film roll obtained above, and while running in the horizontal direction, it was immersed in a water tank at a water temperature of 30°C to swell and stretched 1.7 times in the machine direction (MD). . Then, the film was immersed in an aqueous solution containing 0.5 g/L of iodine and 30 g/L of potassium iodide at 30° C. and stretched 1.6 times in the machine direction (MD) while being dyed. Next, the film was immersed in an aqueous solution (50° C.) containing 40 g/L of boric acid and 30 g/L of potassium iodide, and uniaxially stretched 2.0 times in the machine direction (MD) while cross-linking with boric acid. Finally, the film 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 with a total draw ratio of 5.6.
During the production of the polarizing film using the entire polyvinyl alcohol film (16,000 m), the polyvinyl alcohol film was not broken.

<Comparative example>
In Example 1, the tape was a double-sided tape with a width of 50 mm, and the tape was positioned axially above the predetermined position 5a where the axial center of the core body 1 and both side edges of the polyvinyl alcohol film to be wound were located. It was attached in a ring shape to a total of three locations, one at a position 20 mm away from the central side of the direction. Other portions of the film winding core were the same as in Example 1 above.
Then, the same polyvinyl alcohol film as in Example 1 was wound around the film core in the same manner as in Example 1 to prepare a polyvinyl alcohol film roll. The appearance evaluation results of the obtained polyvinyl alcohol film roll are also shown in Table 1 below.
A polyvinyl alcohol-based film was unwound from the polyvinyl alcohol-based film roll, and a polarizing film was produced in the same manner as in Example 1. could not be manufactured.

From the results in Table 1 above, it can be seen that the type and winding method of the tapes 2 and 3 on the film core are more effective in preventing winding slippage in Examples 1 and 2 than in the comparative example.
Further, it can be seen that the production of the polarizing film is stabilized when the polyvinyl alcohol film is unwound from the polyvinyl alcohol film rolls of Examples 1 and 2, in which there is almost no winding displacement (the amount of winding displacement is less than 1 mm).

Further, in Examples 1 and 2, even when the winding angle θ of the tape 2 was set to 20° and 70°, the same tendency as in Examples 1 and 2 was obtained.
Furthermore, in Examples 1 and 2, the position of the end 2b of the tape 2 is set to a position 10 mm and 300 mm to the center in the axial direction from the planned position 5a where both side edges of the polyvinyl alcohol film to be wound are located. Also, results showing the same tendencies as in Examples 1 and 2 were obtained.

Although specific embodiments of the present invention have been described in the above examples, the above examples are merely illustrative and should not be construed as limiting. Various modifications apparent to those skilled in the art are intended to be within the scope of the invention.

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

1 core body 2 tape 5 film

Claims (7)

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 helical winding direction of the tape is opposite to the first end side and the second end side from the axial center of the core body,
A winding core for a film, wherein a gap is provided between adjacent tapes in each spirally adhered tape. 2. The film core according to claim 1, wherein the tape is helically attached in a symmetrical manner with respect to a plane passing through the axial center of the core body and perpendicular to the axis. 3. The film core according to claim 1, wherein the angle of the winding direction of the spiral tape with respect to the axial direction of the core body is in the range of 20 to 70 degrees. The positions of the ends of the tape located at both ends of the core body are in the range of 10 to 300 mm toward the center in the axial direction from the expected positions of both side edges of the film wound on the film core. The film winding core according to any one of claims 1 to 3, which is inside. The helical tape is arranged on the axial center side of the predetermined positions where both side edges of the film to be wound on the film winding core are positioned, and on both axial end sides of the end portions of the helical tape. 5. The film winding core according to claim 4, wherein a tape is attached in a ring shape separately from the tape. The film core according to any one of claims 1 to 5, wherein the length in the axial direction is set to 3 m or more, and a film having a width of 3 m or more and a length of 5000 m or more wound on the core A polyvinyl alcohol-based film roll comprising a polyvinyl alcohol-based film. 7. The polyvinyl alcohol film roll according to claim 6, wherein the water content of said polyvinyl alcohol film is in the range of 0.1 to 4.0% by weight.

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