JPH0798594B2 - Winding method for thermoplastic resin film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a winding method for winding a relatively thin thermoplastic resin film of 25 μ or less in a roll shape with a slitter, and particularly good winding that does not change with time. Concerning the winding method to get the figure.

[Prior Art] In the process of manufacturing a thermoplastic resin film, a film formed to a certain extent wide is cut by a slitter into a band-shaped film of a predetermined width, which is wound into a roll to be a rolled product. . Since the product wound with this slitter is the final product shipped to the secondary processing manufacturer, the surface layer portion as well as the inner layer portion must be free from defects such as wrinkles.

However, a relatively thin thermoplastic resin film having a thickness of 25 μm or less has a problem that wrinkles are more likely to occur than a thick film. It is generally known that wrinkles in a thermoplastic resin film winding product are controlled to some extent by temperature and humidity. That is, if there is an undesired change in temperature or humidity, the film is slightly affected by the influence of the change, and wrinkles are generated due to the change in size itself or the loss of stress balance. In particular, the surface layer exposed to the atmosphere is easily affected by temperature and humidity, and wrinkles tend to occur.
Wrinkles 2 (hereinafter referred to as vertical wrinkles) extending in the winding method of the wound product 1 as shown in FIG. 1 may occur.

In addition, air is caught depending on the winding tension and the surface roughness of the film during winding of the product, and after the winding, the air is released to some extent from the inside of the winding layer, but if a large amount of air escapes. Wrinkles are likely to occur at that portion. Air is more likely to escape on the surface layer side, and in the case of a thin film wound product having a weak stiffness, wrinkles may be generated in the surface layer portion due to air escape over time.

Further, since the wound product is wound while a certain amount of tension is applied to the film, there is residual stress in the inner layer of the wound product roll. However, since it is a resin film, stress relaxation occurs over time, the residual stress value itself and its distribution change, and wrinkles may occur over time due to the change. Particularly, in the surface layer portion, the tension applied at the time of winding is completely lost after the winding, so that the change in stress is larger than that in other portions, and wrinkles due to the change in residual stress are likely to occur.

In order to deal with the problem of wrinkling as described above, the wound product is wound softly and the residual stress of the wound product winding layer is kept small originally, and conversely, depending on the surface roughness and slipperiness of the film. It is known that the winding amount is thoroughly hardened and the amount of air trapped between the winding layers of the wound product is originally reduced.

[Problems to be Solved by the Invention] However, in the method of softly winding the winding product,
Although the residual stress is reduced, the amount of air trapped during winding increases, which causes another problem that the film easily gets lost during winding.Moreover, the amount of air trapped increases the amount of air released after winding. If the amount of air also increases and a large amount of air escapes, there is a problem that wrinkles 3 (hereinafter referred to as horizontal wrinkles) extending in the width direction of the product 1 as shown in FIG. 4 occur.

In the method of winding the film thoroughly and hard according to the surface roughness of the film, the dimensional change of the film is suppressed to a high winding hardness, and the occurrence of surface vertical wrinkles over time tends to be prevented. If the film has uneven thickness, the thick part is strongly stretched and the thin part is sagged, so that the flatness of the film is deteriorated as a whole, which may cause a problem in secondary processing such as coating.

The present invention focuses on the problems as described above, and although some loss as a product is increased, it does not cause wrinkles due to trouble during winding or air release, and has a bad influence on the flatness of the film. An object of the present invention is to provide a winding method that does not reach and to stably obtain a wound product having a good winding shape without wrinkles.

[Means for Solving the Problems] A method for winding a thermoplastic resin film according to the present invention in accordance with this object is a roll-shaped winding while cutting a thermoplastic resin film having a thickness of 25 μ or less into a strip shape with a slitter. In the winding method of the thermoplastic resin film wound on the product, the surface layer portion of the rolled product wound into the roll, after winding the wound product,
According to the center line average roughness (Ra) of the film surface, it is removed by at least 30 m or more.

Here, the center line average roughness (Ra) refers to that specified in the item of surface roughness of JIS-B0601, and the cutoff value is 0.25 mm.
It is measured by.

The thermoplastic resin as referred to in the present invention means, for example, a resin such as polyester, polyamide, polyphenylene sulfide, etc., among which a resin mainly containing polyester is preferable. Regarding the film thickness, a thin film having a thickness of 25 μm or less, which easily causes wrinkles, is symmetrical, and a film having a thickness of 12 μm or less is particularly effective when the present invention is applied.

Further, the removal length of the surface layer portion of the rolled product is at least 30 m, but the upper limit is preferably as short as possible so that the loss amount is small and the removal length is not particularly limited, but the removal length is preferably 800 m or less. The time of removal of the film is not particularly limited, but it is preferably 1 hour after the winding and 24 hours after the winding.

The removal length L [m] of the film and the center line average roughness Ra [μ] of the film surface have the following relationship. This relationship is compatible with the results of the examples shown in Table 1 below.

When Ra ≧ 0.022 [μ], L ≧ 30 [m] When Ra <0.022 [μ], L> 30 {3.5 (100Ra) ² −18.5 (100Ra) +24.76} [m] In the present invention, It is preferable that the winding hardness of the surface layer portion of the wound product wound into a roll is 86 to 96 degrees, and 88 to 92.
More preferably, When the hardness is within this range, horizontal wrinkles and the flatness of the film are improved, which is preferable. In addition,
The winding hardness of the film surface layer is measured according to JIS K6301-1975 spring type hardness test A type. Specifically, using a Shimadzu Rubber Hardness Tester Model 200 (manufactured by Shimadzu Corporation), the pressing load is measured as 1 kg within 30 minutes immediately after the completion of film winding.

The width of the film wound into a roll in the present invention is not particularly limited, but is preferably 300 mm or more, 500
mm or more is more preferable, and 700 mm or more is the most preferable.

[Operation] In the winding method as described above, the winding product is determined within an appropriate time after winding, according to the center line average roughness (Ra) of the film surface of the winding film from its surface layer portion. The wound length is removed. This part is a part where wrinkles will occur if left as it is, or wrinkles have already started within a short time after winding, and it is considered that the stress change after winding is the largest. It is a part that is easily affected by temperature and humidity. Since the surface layer where wrinkles tend to occur is removed after winding, it is not necessary to change the winding conditions themselves, but it is possible to set the optimum winding tension etc. according to the characteristics of the film. You can
In particular, it is not necessary to use soft or hard winding. Therefore,
The air entrapment rate is appropriately controlled during winding to prevent stray winding, and after winding, a large amount of air is prevented from escaping from the winding layer and horizontal wrinkles are prevented. Further, since a proper amount of air is held in the wound layer of the wound product, the problem of deterioration of the flatness of the film does not occur.

In this way, because a certain amount of film is removed from the surface layer, the amount of loss increases slightly, but wrinkles can be prevented and problems in secondary processing can also be prevented, so it is possible to see comprehensively. For example, the product acceptance rate is improved.

[Examples] Examples of the present invention will be described below.

The center line average roughness (Ra) of the film surface in the present invention,
The following tests were conducted in order to clarify the relationship with the removal length of the surface layer of the rolled product. In the test, a polyester film with a thickness of 9μ was manufactured by a biaxial stretching method, once wound as a wide intermediate product, and then a slitter with a width of 1000 mm
While being cut into a strip-shaped film, the roll was wound into a roll having a length of 7,000 m. After the lapse of 4 hours, a predetermined length of partial cut was removed from the surface layer of the wound product to obtain a final product. Although there were no defects in the surface layer of the wound product immediately after winding, the final product after removing various lengths of the surface layer was left at room temperature and humidity for 1 week and the vertical The occurrence of wrinkles was investigated.
The above-mentioned investigation was conducted by changing the film surface roughness and the product surface hardness. The results are shown in Table-1.

The Ra value in Table 1 is the center line average roughness of the film surface in the present invention, and is the result at a cutoff value of 0.25 mm. Further, the surface hardness of the wound product was measured using a rubber hardness meter (manufactured by Shimadzu Corporation) based on JIS standards, and the average value of 7 points measured in the product width direction was used.

In Table 1, the criterion for the vertical wrinkle defect in the surface layer of the product is ◯ with no vertical wrinkles, and wrinkles 2 extending almost all around the winding direction were generated as shown in FIG. 2 and wrinkles 5 which are strong and long, such as wrinkles 4 intersecting in an X shape over the entire circumference as shown in FIG. 2, and wrinkles 5 as shown in FIG. △, the degree of occurrence and the length is mild
And

As can be seen from Table-1, there is an optimum removal length depending on the surface roughness of the film and the surface hardness of the product, and wrinkles can be prevented by removing this portion.

The lower the surface hardness, the shorter the cut-and-removed length, but conversely, horizontal wrinkles tend to occur immediately after the slit. In the test examples of Table-1, the surface hardness of 88 degrees or less is not preferable. In other words, some horizontal wrinkles occurred even at 88 degrees, and the overall product acceptance rate was best at 90 degrees. Thus, when wound with an appropriate hardness that is neither too soft nor too hard, the surface layer portion is removed according to Ra (the smaller Ra is, the longer the removal length is). It is possible to prevent wrinkles from being generated on the surface layer of the rolled product.

Regarding the time to remove the surface layer after slitting, it is better to cut and remove as soon as possible after slitting in consideration of phenomena such as winding tightening, but for the surface layer to the inner layer, temperature, humidity, etc. Considering that it is a cover, it is preferable to remove it after some time. However, as a result of comparing those removed immediately after slitting, those removed 4 hours after slitting, and those removed 48 hours after slitting, there was no big difference. Therefore, the time to be removed can be appropriately set depending on the process and the like.

[Effects of the Invention] As described above, according to the method for winding a thermoplastic resin film of the present invention, a product having a certain length depending on the center line average roughness (Ra) of the film surface after slit winding is taken up. Since the film is removed from the surface layer, it is possible to reliably prevent the occurrence of wrinkles in the product surface layer while winding the wound product with an appropriate hardness that does not cause a large amount of air escape or deterioration of flatness. It is possible to obtain an effect that a product having no defects can be stably obtained.

[Brief description of drawings]

1 to 3 are perspective views of a rolled product with vertical wrinkles, and FIG. 4 is a perspective view of a rolled product with horizontal wrinkles. 1 ... Rolled product 2, 4, 5 ... Vertical wrinkle 3 ... Horizontal wrinkle

Claims (6)

[Claims] 1. A thermoplastic resin film having a thickness of 25 μm or less,
In the winding method of the thermoplastic resin film to be wound into a roll-shaped winding product while being cut into a strip shape with a slitter, the surface layer portion of the roll-shaped winding product, after winding the winding product, the film While removing at least 30 m or more according to the center line average roughness (Ra) of the surface, the removal of 30 m or more of the surface layer portion makes the center line average roughness of the film surface Ra [μ],
When the removal length of the film is L [m], the following formula Ra ≧ 0.022 [μ], L ≧ 30 [m] Ra <0.022 [μ], L> 30 {3.5 (100Ra) ² A method for winding a thermoplastic resin film, which comprises removing a film having a length of -18.5 (100Ra) +24.76} [m]. 2. The winding of the wound product is within 1 hour after the winding of the wound product, or within 24 hours after the winding of the wound product. A method for winding a thermoplastic resin film as described above. 3. The roll-shaped rolled product has a film width of 30.
The method for winding a thermoplastic resin film according to claim 1, which is a roll-shaped product having a length of 0 mm or more. 4. The method for winding a thermoplastic resin film according to claim 1, wherein the surface layer of the wound product is the surface layer of the wound product having a winding hardness of 86 to 96 degrees. . 5. The method for winding a thermoplastic resin film according to claim 1, wherein the thermoplastic resin is polyester. 6. The method for winding a thermoplastic resin film according to claim 1, wherein the thermoplastic resin film is a thermoplastic resin film having a thickness of 12 μm or less.