JPH01178528A - Polypropylene film - Google Patents

Abstract

PURPOSE:To obtain a film which does not slide during high-speed winding and has good antiblocking property suitable for a nonmetallized product, by providing a polypropylene film with a specified part treated with corona discharge in the form of longitudinal stripes. CONSTITUTION:A polypropylene film at least either of whose surfaces is provided with a part treated with corona discharge in the form of longitudinal stripes, composed of alternately arranged 2-30mm-wide parts strongly treated with corona discharge and 2-50mm-wide parts weakly treated with corona discharge, wherein the wet tension of the weakly treated part is 39dyn/cm or below, the difference in the wet tension between the strongly treated part and the weakly treated part is at least 1dyn/cm. When the width of the longitudinal stripe of the strongly treated part is below 2mm, the slide preventing effect is small, and when it is above 30mm, blocking is apt. to occur in the case of a narrow film of a width of below 50mm. Further, when the width of the longitudinal stripe is below 2mm, blocking is apt. of occur, and when it is above 50mm, an effect which is at most equivalent to that of a conventional art can be obtained in the case of a narrow film of a width below about 70mm.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to polypropylene films.

(Prior Art) Polypropylene films have recently come to be widely used in industrial applications.

Along with the increase in demand, the demand for high-speed hroe properties is also increasing. Winding properties and slitting properties are also one of them.

However, as speeds increase, meandering, misalignment, and the like are more likely to occur during winding and slitting, which is an impediment to productivity and processability.

Therefore, it has been considered to impart high-speed durability such as high-speed winding property to the polypropylene film itself. For example, in metal vapor deposition applications, it has been proposed to apply uniform corona discharge treatment to non-metallic surfaces (for example,
No. 8-16415).

However, these conventional techniques are insufficient for high-speed running of 400 m/min or more, high-speed winding, etc. In order to prevent this, if a strong treatment exceeding 33 dyne/cm is applied, there is a limit such as blocking and wrinkles, which is a defect especially in non-vapor deposition applications.

[Problem that the invention seeks to solve]

In view of this problem, the inventors of the present invention, as a result of intensive study, found that 4.
We have found a polypropylene film that does not shift even when wound at high speeds of 00 m/min or more and has good blocking properties that can withstand non-vapor deposition applications.

[Means for solving problems′]

The present invention provides a corona discharge treated part with a width of 2 to 30 mm on at least one side of a polypropylene film, and a 2 to 5O1II
Vertical stripe corona discharge treatment is performed in which corona discharge field treatment areas of II1 width are alternately located, and the wetting tension of the strong treatment area is 33 to 40 dyne/cm, and the wetting tension of the weak treatment area is 39 dyne/cm. /cm or less, and the difference in wetting tension between the strongly treated part and the weakly treated part is not less than 'l dyne/Cm.

In the present invention, the width of the vertical stripe of the corona-resistant and strong-treated portion is
The length is 2 to 30 mm, preferably 3 to 30 mm. 2
If it is less than 30mm, the effect of preventing slippage will be small, and 30Illll
If it exceeds I, blocking will easily occur if the film is narrow, about 50 mm or less in width.

In addition, the width of the vertical stripes in the corona discharge field treatment section is 2 to 50 m.
m, preferably 5 to 4 Qmm.

If it is less than 2mm, blocking is likely to occur, and if it is less than 50m
If the width exceeds m, only the same effect as the conventional technique can be obtained for a narrow film having a width of 7 Q mm or less.

It should be noted that this longitudinal corona discharge treatment line does not need to be at a fixed position in the width direction, and may be moved singly or as a whole, and there is no problem even if the line intersects as a result. Also,
The width may also vary as long as it is within the above range.

The wetting tension of the corona discharge strong treatment section is 33 to 40 dyne.
/cm, preferably 34 to 38 dyne/cm.

If it is less than 33 dyne/cm, there is no effect of preventing winding slippage, and if it exceeds 40 dyne/cm, blocking or wrinkles are likely to occur.

On the other hand, the wetting tension of the corona discharge field treatment section is 39 dyne.
/ cm or less, preferably 37 dyne/Cm or less. If it exceeds 39 dyne/cm, blocking and wrinkles are likely to occur. Note that it may be untreated.

The difference in wetting tension between the strongly treated part and the weakly treated part is 1 dyne/c.
m or more. If it is less than 1 dl/ne/Cm, only the same effect as the conventional technology can be obtained.

Note that the atmospheric gas for the corona discharge treatment is not particularly limited, and may be air or other gas such as nitrogen or carbon oxide.

Moreover, the polymer of the polypropylene film of the present invention is
In addition to propylene homopolymer, it may be a copolymer of propylene and, for example, ethylene or butene, or a blend of polypropylene and other α-olefin polymers such as polyethylene or polypropylene.

Further, the method for producing the polypropylene film before corona discharge treatment is not particularly limited, but for example, H is 94
% or more of polypropylene resin at an extruder temperature of 190-2
After melting at 80°C and extruding it into a sheet through a slit T-guid, it is cooled and solidified with a cooling roll at 20 to 95°C. Hold this sheet at 120-150'C in the cutting direction.
Stretched 3 to 6 times at a temperature of 140 to 1
Stretched 7 to 12 times at a temperature of 70°C, with a roughness of 150 to
It is possible to use one that has been heat-treated at a temperature of 170°C to obtain 1q.

Further, the polypropylene film of the present invention is usually “l”.
The target width is Qmm or more, preferably 300mm or more.
It has a width of mm or more.

In addition, in this invention, the measuring method of wetting tension is as follows. That is, the wetting tension was measured according to JISK 676B, except that the wetting liquid application direction was limited to the length direction.

〔Example〕

Next, the present invention will be explained by examples.

Example 1 Thickness: 10 μm, width: 500 mm without corona discharge treatment
On one side of a biaxially stretched polypropylene film with a length of 2000 m and a width of 20 mm and a wet tension of 366 mm,
A corona discharge-treated film was prepared with a weak treatment area width of 30 mm and a wet tension of 34 dyne/cm.

The film was slit into 6 strips of 80 mm width at a speed of 400 m/min using a slitter manufactured by Tsubasa Manufacturing Co., Ltd., and wrinkles, winding misalignment, and blocking at the unwinding portion were observed and judged.

Note that 'lQmm at both ends were assimilated.

The criteria for determining roll misalignment and wrinkles were as follows.

(1) When the number of slit products in which a winding deviation of 2 mm or more occurred was 0, it was marked as ○, when it was 1 to 2, it was marked as Δ, and when it was 3 or more, it was marked as ×.

(2) If the number of wrinkle-free slit products is 6, ○, 4 to 5
In the case of books, it was marked as △, and in the case of 3 or less books, it was marked as ×.

The results are shown in Table 1.

Example 2 The same procedure as Example 1 was carried out except that the width of the image processing section was 25 mm and the width of the weak processing section was 3 mm. The results are shown in Table 1.

Example 3 The same procedure as in Example 1 was carried out except that the width of the image processing section was 5 mm and the width of the weak processing section was 45 mm. The results are shown in Table 1.

Example 4 The procedure was the same as in Example 1 except that the wetting tension of the image processing section was 406 dyne/cm and the wetting tension of the weak processing section was 33 dyne/cm. The results are shown in Table 1.

Example 5 The same procedure as Example 4 was carried out except that the wetting tension of the weakly treated part was 396 yne/cm. The results are shown in Table 1.

Example 6 The procedure was the same as in Example 1, except that the wetting tension of the image processing area was 33 dyne/cm and the portion corresponding to the weakly processed area was left untreated. The results are shown in Table 1.

Example 7 The same procedure as in Example 1 was carried out except that the wetting tension of the image processing section was 346 dyne/cm and the wetting tension of the weak processing section was 33 dyne/cm. The results are shown in Table 1.

Comparative Example 1 The same procedure as Example 1 was carried out except that the width of the image processing section was 4Qmm and the width of the weak processing section was 5mm. The results are shown in Table 1.

Comparative Example 2 The same procedure as Example 1 was carried out except that the width of the image processing section was 5 mm and the width of the weak processing section was 60 mm. The results are shown in Table 1.

Comparative Example 3 The wetting tension of the image processing section was 42 dVne/Cm, and the wetting tension of the weak processing section was 33 dVne/Cm.
The procedure was the same as in Example 1. The results are shown in Table 1.

Table 1 [Effects of the Invention] According to the present invention, it was possible to obtain a polypropylene film that does not cause wrinkle blocking or slippage even when slitting at a high speed of 400 m/min and winding at a high speed.

Claims (1)

[Claims] (1) On at least one side of the polypropylene film, 2
A vertically striped corona discharge treatment is performed in which strong corona discharge treatment areas with a width of ~30 mm and weak corona discharge treatment areas with a width of 2 to 50 mm are arranged alternately, and the wetting tension of the strong treatment area is 33 to 4.
0dyne/cm, wetting tension of the weakly treated part is 39dyne
e/cm or less, and the difference in wetting tension between the strongly treated part and the weakly treated part is 1 dyne/cm or more.