JPH0729708B2 - Film roll winding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for winding a film on a winding core in a roll shape, and particularly to winding a film roll for winding while applying surface pressure by a contact pressure roll. Regarding taking method.

[Prior Art] In a method of winding a flexible plastic film such as a polyester film in a roll shape, in order to obtain a good winding appearance, for example, as shown in FIG. Roll 3 with appropriate winding tension
It is generally well known to wind the film into a shape and apply an appropriate surface pressure by the contact pressure roll 4. The winding hardness of each winding layer of the film roll wound by such a winding method is mainly determined by the conditions of winding tension and surface pressure. That is, when the winding tension is large, the winding tends to be hard, and when the surface pressure is large, the winding tends to be hard.

Conventional winding conditions are usually such that the surface pressure is kept constant from the beginning to the end of winding and the winding tension is gradually reduced from the beginning to the end of winding. The winding hardness of the film roll wound under such winding conditions generally shows the characteristics shown in FIG. 5 between the core of the film roll and the surface layer.

However, between the winding hardness and the occurrence of defects of the film roll immediately after winding or after being left for a long time,
There is the following correlation. That is, when the winding hardness in the core portion exceeds a certain value (depending on the film thickness, physical properties, etc.) (area A), winding core wrinkles are likely to occur, and the winding hardness in the surface layer portion is higher than the certain value. When it is also low (region B), surface wrinkles are likely to occur due to moisture absorption after standing. In the conventional winding method with constant surface pressure,
When the surface pressure is set high, the winding hardness in the surface layer increases and it is possible to improve in the direction of eliminating defects, but since the winding hardness in the winding core also increases, winding wrinkles are more likely to occur, and conversely the surface pressure is reduced. When set to a low value, the defects in the core part are improved, but the surface layer part is too soft and the surface layer wrinkles tend to increase, and both the core wrinkle and the surface layer wrinkles can be obtained only by setting the surface pressure. Was difficult to improve. Although it is possible to solve the above-mentioned drawbacks depending on the winding tension condition, in general, the winding tension has a narrow range of conditions that can be adopted as compared with the surface pressure, and if the winding tension exceeds a certain allowable value, the film winding is performed. Wrinkles will already occur when picking up. Therefore, if it is attempted to eliminate the above-mentioned drawbacks depending on the winding tension condition, the winding tension at the beginning of the winding is kept relatively low, and the winding tension at the end of the winding is higher than before, and in some cases, It is possible to make it higher than the winding tension, but if the winding tension at the beginning of the winding becomes too low, winding deviation tends to occur during unstable conditions at the start of the winding speed, and the winding tension at the end of winding may increase. If it becomes too high, wrinkles will already occur on the film having low rigidity during winding, and in reality it was difficult to set the optimum conditions only by the winding tension.

To solve the above problems, conventionally, a method of increasing the winding tension at the end of winding in order to prevent wrinkles on the surface layer (Japanese Patent Laid-Open No. 50-20).
174), a method of lowering the surface pressure at the end of winding in order to adjust the air trapping rate of the surface layer (Japanese Patent Publication No. 54-39430).
A method of making the winding hardness of the surface layer higher than the winding hardness of the middle layer in order to prevent wrinkling of the surface layer over time (JP-A-61-2386).
No. 39) is known.

[Problems to be Solved by the Invention] However, in the method disclosed in Japanese Patent Laid-Open No. 50-20174, since the range of conditions of winding tension that can be actually taken is narrow as described above, winding at the end of winding There is a problem that the take-up tension is too high, and there is a strong possibility that surface wrinkles will already occur during winding. Further, no means for solving the core wrinkle is disclosed.

In the method disclosed in Japanese Examined Patent Publication No. 54-39430, from the viewpoint of winding hardness, the direction is in the region B of FIG. 5 described above, so that it is actually difficult to suppress surface wrinkles. It is in. Further, no solution is disclosed for the core wrinkle.

Further, in the method disclosed in JP-A-61-238639, the winding hardness magnitudes of the middle layer portion and the surface layer portion of the film roll are opposite to those shown in FIG. Cause problems. The winding hardness indicates the hardness of each winding layer part including the air layer interposed between the film layers in a wound state. However, since the film is wound in a roll shape, the film on the outer layer side is wound. The layer exerts a radial force on the film layer on the inner layer side, and the higher the winding hardness, the greater the force acting on the inner layer side. Therefore, when the winding hardness of the surface layer portion is higher than that of the middle layer portion of the film roll, the force acting from the surface layer portion to the middle layer portion according to the winding hardness of the surface layer portion is the above according to the winding hardness of the middle layer portion. The drag force of the middle layer portion against the force acting from the surface layer portion becomes smaller, the middle layer portion cannot withstand the radial force from the surface layer portion, and the film layer bends due to buckling or the like.
Such a phenomenon induces a new defect that wrinkles occur in the middle layer. Therefore, in order to prevent wrinkles in the middle layer portion (or further wrinkles on the winding core side) from occurring, it is necessary to gradually reduce the winding hardness from the winding core portion to the surface layer portion, as disclosed in JP-A-61-238639. The method disclosed in the publication does not satisfy this condition.

The object of the present invention is, together with the problems in the above-described conventional general surface pressure constant winding method, focusing on the problems in each of the above-mentioned proposed techniques, without inducing wrinkles in the middle layer of the film roll, It is an object of the present invention to provide a method capable of eliminating both core wrinkles and surface wrinkles at the same time.

[Means for Solving Problems] A method for winding a film roll according to the present invention, which meets this purpose, comprises:
When the film is wound into a roll on the winding core while applying the surface pressure by the contact pressure roll, the film is wound so that the winding hardness of the wound film roll gradually decreases from the core side of the film roll to the surface layer side. A method of winding a film roll for controlling the take-up tension comprises a method of increasing the surface pressure of the contact pressure roll in the surface layer portion as compared with the surface pressure of the winding core portion.

Here, the surface pressure in the surface layer portion is preferably 500% or less, more preferably 200% or less, still more preferably 150% or less, as compared with the surface pressure in the winding core portion.
This increase characteristic may be linearly increased or curvilinearly increased with respect to the winding diameter of the film roll from the winding core portion to the surface layer portion.

[Operation] In such a winding method, the winding tension is controlled to gradually decrease with an increase in the winding diameter, and the winding tension is controlled so that the winding hardness gradually decreases from the winding core portion to the surface layer portion. The winding hardness of the portion is higher than that of the middle layer portion, and the winding hardness of the middle layer portion is higher than that of the surface layer portion, and the magnitude relationship is not reversed. Then, since the surface pressure of the surface layer portion is increased, the winding hardness in the surface layer portion becomes larger than the characteristic shown in FIG. 5 of the related art, and it is improved to a region where the surface layer wrinkle defect does not occur. When the surface layer portion is wound tightly, a radial force corresponding to the winding hardness acts on the middle layer portion, and further acts on the winding core portion via the middle layer portion. The force acting on the core part winding layer radially inward from the outer layer acts to reduce the diameter of the core part winding layer and, as a result, to reduce the winding hardness of the core part. Since the winding core inner layer side is the surface of the winding core that is not deformed (reduced in diameter), the winding layer in the immediate vicinity of the winding core maintains the same winding hardness as the conventional winding layer, and the winding layer on the outer side of the winding layer. In this part, the winding hardness decreases relatively rapidly. Therefore, the outermost layer of the winding core is maintained at a necessary winding hardness so that winding deviation does not occur when the winding speed rises, and is lower than the conventional winding hardness when the entire winding layer winding layer is viewed. As a result, the area is improved to the area shown in FIG.

As a result, the winding hardness from the core portion to the surface layer portion is secured, while the winding hardness in the winding core portion is reduced and the winding hardness in the surface layer portion is increased, and both the core wrinkle and the surface wrinkle are formed. Is prevented.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the control characteristic of the surface pressure according to the method of the present invention in relation to the winding diameter. The surface pressure is constantly applied during film winding by a contact pressure roll as shown in FIG. Assuming that the value at the core is 100%, this surface pressure increases to a value larger than that at the surface layer, that is, as a general range of use, increases to a value in the range of more than 100% and less than 200%. Controlled. In the case of winding a polyester film of about 1 to 100 μm, it is more practically 150
It is preferred to increase it to a value below%. However, depending on the type of film and the winding tension condition described later, the range to be increased can be up to about 500% or less.

The characteristic of increasing the surface pressure with respect to the winding diameter may be such that it gradually decreases linearly as shown in characteristics A and B of FIG. 1, and as shown in characteristic C, it increases almost to the vicinity of the surface layer portion. Instead of this, any method may be used, in which the surface layer portion is rapidly increased to a predetermined value, or a large amount is increased in the vicinity of the winding core portion and then gradually increased.

Further, in the method of the present invention, the winding tension is controlled so that the winding hardness of the film roll gradually decreases from the core side to the surface layer side. Such a winding hardness characteristic is achieved by gradually reducing the winding tension. For example, as shown in FIG. 2, the winding tension F may be controlled to be gradually reduced as the winding diameter increases. The control pattern of the winding tension can also have a curved characteristic as shown by the chain double-dashed line in FIG. 2 in addition to the linear characteristic.

As a more specific control example of the above-mentioned surface pressure and winding tension, a thickness of 12
When winding a polyester film of μm onto a winding core with a core diameter of 168 mm at a final winding diameter of 500 mm, for example, the surface pressure is increased from 20 kg / m at the core to 35 kg / m (175%) at the surface layer, This is a method of gradually reducing the winding tension from 11 kg / m to 8 kg / m. In the case of a polyester film having a thickness of about 25 μm, the surface pressure was small with a relatively small increase of about 50 kg / m to 60 kg / m (120%).

The respective layer winding hardnesses of the film roll obtained under the winding conditions such that the winding tension is gradually reduced and the surface pressure is increased are as shown in FIG. 3, for example.

That is, as described above, due to the increase in the surface pressure in the surface layer portion, the surface layer portion is wound harder than in the conventional method, and the winding hardness in the surface layer portion deviates from the defect (surface layer wrinkle) generation region B. In addition, the winding hardness of the winding core portion, except for the outermost layer of the winding core, is relatively sharply decreased as compared with the conventional method, and the winding hardness of the winding core portion as a whole is also a defect (core wrinkle) occurrence area A. Get out of. Since the winding hardness from the winding core portion to the surface layer portion is characterized by gradually decreasing by the winding tension control, wrinkles may be generated in the middle layer portion by the radial force from the outer layer portion. Absent. Therefore, it is possible to prevent both the core wrinkle and the surface wrinkle from occurring while ensuring a good winding appearance of the middle layer portion.

[Advantages of the Invention] As described above, according to the film roll winding method of the present invention, the winding hardness is gradually controlled while controlling the winding hardness from the winding core portion to the surface layer portion of the film roll while controlling the winding tension. Since the surface pressure of the surface layer portion is increased with respect to the core portion, the winding hardness of the surface layer portion is larger than that of the conventional method without causing defects such as wrinkles in the middle layer portion of the film roll, There is an effect that the winding hardness can be made smaller than that of the conventional method, and both of them can be positioned in the area where no defect occurs, and both the core wrinkle and the surface layer wrinkle can be prevented at the same time.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing each pattern of surface pressure control in the film roll winding method of the invention, FIG. 2 is a characteristic diagram showing a winding tension control example in the method of the invention, and FIG. 3 is a method of the invention. FIG. 4 is a winding hardness characteristic diagram of the film roll obtained in FIG. 4, FIG. 4 is a schematic side view of a film winding device using a general contact pressure roll, and FIG. 5 is a winding hardness characteristic diagram of a conventional film roll. 1 ... Winding core 2 ... Film 3 ... Film roll 4 ... Contact pressure roll I, B, C, D ... Surface pressure control pattern F ... Winding tension

Claims (1)

[Claims] 1. When winding a film around a winding core while applying a surface pressure by a contact pressure roll, the winding hardness of the wound film roll gradually decreases from the core side of the film roll to the surface layer side. In the film roll winding method for controlling the winding tension of the film as described above, the surface pressure of the contact pressure roll is such that the surface pressure in the surface layer portion is increased as compared with the surface pressure in the winding core portion. Winding method.