JPS5816415A - Electric orientation polypropylene film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to oriented polypropylene films for electrical applications.

Stretched polypropylene film as dielectric.

Stretched polypropylene films for electrical applications are known, which are used in capacitors, etc., by vapor-depositing metals such as aluminum and zinc on one side to form electrodes. Because it has.

Its use as a dielectric material in capacitors is steadily increasing.

As the amount used increases, the productivity of processing processes such as film stretching, vapor deposition, and capacitor element winding is significantly improved, and speeds are increasing.

l2. However, with the increase in speed, meandering, cross-sectional deviation, creases, etc. are becoming more likely to occur during unwinding and unwinding, and this has become a problem and an impediment to improving productivity.

The cause of meandering and cross-sectional deviation is due to the speeding up of the winding process.
This is thought to be due to an increase in the amount of air caught between the films when the film is wound, that is, the amount of conveying air.

Furthermore, if there is a variation in film thickness, that is, a deviation, as the winding diameter increases, it becomes more likely to shift.In order to solve this problem during high-speed winding, it is necessary to equalize and reduce the amount of conveying air.

Alternatively, it is necessary to remove the trapped air to prevent the film from shifting.

As a solution to these problems, for example, there is a method of improving the machine precision or adjusting the tension during one winding, but there is a limit to improving the machine precision of existing equipment, and in reality it is difficult to do so. In addition, the method of adjusting the tension during winding specifically makes the winding f stiffer, which is undesirable as it leads to the occurrence of sagging. This sagging will be further exacerbated if the variation in film thickness is large.

Therefore, as a solution, it is desirable to improve the kC film itself without making any major changes to the machinery or operating conditions.

As mentioned above, cross-sectional deviation and meandering are thought to be caused by an uneven increase in the amount of conveyed air.1 For example, methods have been taken to make it easier for conveyed air to escape by forming irregularities on the surface layer of the film. However, on the other hand, this increases the slipperiness of the film, resulting in the film becoming slippery and meandering.

Therefore, with this method, it is difficult to balance the degree of unevenness and the smoothness, and only an insufficient effect can be obtained.

Taking into account the above points, the present inventors have determined that the degree of surface treatment on the opposite side of the electrical oriented polypropylene film (hereinafter referred to as the vapor-deposited surface) to which the normal surface treatment has been applied (hereinafter referred to as the non-evaporated surface) is We focused on the issue related to the amount of air conveyed during film winding.

The result of intensive study on improving suitability for high-speed winding.

The present invention has now been completed.

That is, by mildly surface-treating the non-evaporated surface of the stretched polypropylene film that undergoes metallization and controlling the slip properties of the film during high-speed winding, the amount of conveying air can be made uniform and the suitability for 14-speed winding and weaving can be improved. was completed.

More specifically, what is the degree of surface treatment of stretched polypropylene film normally used for metal deposition?

For single-sided metallization, normal surface treatment is performed only on the vapor-deposited side, and the degree of treatment is generally 35 to 42 d in terms of surface wetting tension.
yne/CIIM, and the surface wetting tension of the non-evaporated surface, which is the opposite side, is usually 30 to 3.
1 dYne/ex.

On the other hand, the stretched polypropylene film for electrical use of the present invention is a metalized film on one side, and the surface treatment on the S-deposited side is the same as that of a normal deposition film, and the surface treatment on the non-deposited side is corona treatment. 7. And the degree of processing is 33
It is characterized by less than dine/a+s and [,. By subjecting the non-evaporated surface to a weak surface corona treatment, it is possible to control the roughness during high-speed winding, equalize the amount of conveyed air, and prevent the occurrence of meandering, cross-sectional deviation, etc. We were able to.

For this reason, for example, when winding an element for a capacitor,
It can be wound at a high speed of 250 ws/% or higher without any problem, and can be wound with a large winding diameter, so it has the advantage that an element with a large capacitance can be manufactured.

Conventionally, in order to improve the slickness of the film surface, methods such as roughening the surface of the film, adding additives internally, or coating the surface have been proposed and implemented.

Electrical stretching film 11 of the present invention, in which there has been almost no effective method of reducing the snow-slip property of the film and controlling it to an appropriate level, which can achieve the object of the present invention. ．． As mentioned above, propylene film is characterized by having one side subjected to normal surface treatment 1 and the other side being subjected to weak surface treatment 4. Unlike films that have undergone surface treatment, it has special effects that are not found in films that have undergone conventional surface treatment.

In the case of conventional single-sided surface-treated films, depending on the processing conditions, the surface treatment effect may also occur on the opposite side, so-called bleed-through. In this case, bleed-through occurs partially. , the part where the surface treatment effect appears on the opposite side is formed in a plurality of thin strips irregularly in the direction of film travel, with a width of several meters to lQmm.
In this case, as described below, as in the present invention, the surface (non-deposited surface) opposite to the film surface (deposited surface) that has been normally surface-treated is separately subjected to surface treatment, and the surface treatment is uniformly applied to the film surface. Because it is different from the original Z).

The characteristics of the present invention are as follows: 1) The amount of conveyed air is made uniform by reducing the lumpiness to a certain extent by performing a weak surface corona treatment on the non-evaporation surface of the electrical drawn propylene film used for metal deposition.

Since it improves suitability for high-speed winding, it is only necessary to perform surface corona treatment, even if only slightly.

Also, the wetting tension is 33 dyne/.

If the strength is too high, the slip property with the metal-deposited surface will be reduced to 5%, which will not only cause wrinkles but also blocking after one winding, resulting in surface treatment of the metal-deposited film. This is not preferable since there is a possibility that troubles such as transfer to non-evaporated surfaces may occur.

Therefore, the surface treatment jf74 degrees of the non-evaporated surface is 33 d/1i
E74 or lower is appropriate.

The membership fee is that the surface treatment of the film surface be as uniform as possible. If the surface treatment is non-uniform, the slip properties of the obtained film will be non-uniform, corresponding to the unevenness of 8 degrees of treatment, making stable winding work difficult. In the case of weak corona surface treatment, it is extremely difficult to require complete uniformity.
, Iga.

For uniform treatment, it is safe to physically and chemically clean the surface of the electrode by polishing or other means, to keep the distance between the electrode and the roll as small as possible, and to make the width as uniform as possible.

In the electrical oriented polypropylene film of the present invention, only the non-evaporated surface is subjected to a weak surface treatment, and the vapor-deposited surface is subjected to a conventional normal surface treatment.

The properties of the film itself are not impaired, and the productivity thereof is not reduced at all. The surface treatment of the non-evaporated surface may be carried out at the time of weaving the first roll after the metal deposition.

It may be done before or after the film is deposited.

The stretched polypropylene film for electrical use of the present invention is produced by metal vapor deposition on the vapor deposition surface to form one single-sided metallized film, and one winding of the film is performed with a narrow cut, or one winding of the film is performed when winding a capacitor element at high speed. In addition to preventing cross-sectional misalignment and wrinkles, the capacitor element has a large winding diameter! It has the effect of being able to be imitated.

The surface treatment for obtaining the electrical oriented polypropylene film of the present invention may include the commonly known corona discharge treatment, flame treatment, and treatment with chemicals.
9. In the case of the thin electrical-use Fushin polypropylene film, there is a problem of dimensional change due to heat, and chemical treatment may have a negative effect on the electrical properties since it is an electrical-use Sagi-stretched polypropylene film. Therefore, corona discharge treatment is preferred, and the degree of treatment can be controlled by varying the applied voltage, current consumption, film passing speed, etc.

Metallization of the polypropylene polypropylene film 5 is carried out by depositing crystal particles of a metal such as aluminum or zinc (in the case of zinc, silver or steel is preliminarily deposited) on the surface of the film using a conventional vacuum deposition method.

Examples of the present invention will be shown below, but the application examples of the present invention are not limited thereto.

Examples 1 to 2 and Comparative Examples 1 to 3 A biaxial polypropylene film for electrical use having a thickness of 8 μm was used, and a conventional corona surface treatment surface of the same film [wetting tension 38 dyEll! /am) using a vacuum evaporator using a conventional method to deposit aluminum, then on the non-evaporated surface of the reflective metal,
Surface treatments were performed by changing the corona discharge treatment conditions to obtain metallized Fushin polypropylene films with various degrees of treatment.

These metallized films are slittered.

Width: 104) ask cut, one roll was taken up, and then element winding was performed while unwinding one roll using a capacitor element 1 machine (VB-211 manufactured by Limura Seisakusho) to evaluate high-speed winding performance. The results are shown in Table 1.

At the same time, for comparison, the non-evaporated surface was not treated or
Except for passing 31 dyne/am IIc weak treatment.

Comparative Examples 1 and 2 were carried out in exactly the same manner as in the Examples.

The results are shown in Table 1.

Furthermore, spear XI! The physical properties and test methods shown are shown below.

Wetting tension JI8 6768 Bo 11 Ethylene and polypropylene fill 5 Wetting test method C However, 31.5
dyneAMl liquid is 31 d voice e75g liquid and 32
(43 me/w liquid was mixed in the same amount) Contact angle Measured using distilled water in an atmosphere of 20° C. and 6516 H using Kyowa Kagaku ■ CA-P-11111 antenna direct reading device.

Friction coefficient (C slip property evaluation) Measured by A8TMD1894.

A8TM using Toyo Seiki UTM-4LIE Tensilon
Measured according to D1894.

As is clear from the results in Table 1, Examples 1-
The non-evaporated surface of 2 was treated with a weak corona treatment 11 to give a wetting tension of 31.5~
33 dYne/ex, (contact angle 102-94 degrees)
Comparative example 1 has good winding suitability at high speed.
．． The non-evaporated surface of No. 2 was not subjected to corona treatment, and the non-evaporated surface of Comparative Example 3 was subjected to corona treatment, and the wetting tension was 34 d/n.
m (contact angle 90), all have poor winding suitability. From this result, whether the degree of surface treatment on the non-evaporated surface is too weak or too strong, friction resistance (Subtleness)
It is clear that a stretched polypropylene film with good high-speed winding suitability can be obtained by controlling the surface treatment within the range of the present invention.

In addition, in the previous explanation of the conventional technology, it was mentioned that one surface layer was provided with unevenness in order to improve the slip property of the film, but in Comparative Example 2, a film with a roughened surface by providing unevenness on the surface layer was used. ing. The surface roughness of this film is 1.5/
1.2 ()jmax/)Lz'), but the film of other Examples and Comparative Examples has a value of 0.4010.35. Although the winding suitability has been improved, the result is no more than poor gloss on the first winding, and it does not have the same effect as the weak surface treatment of the non-evaporated surface.

Surface roughness of film: Measured using a JI8B0651 surface roughness stylus measuring device.

Examples 3 to 4 and Comparative Examples 4 to 5 Width 52 with a thickness of 6 am and different degrees of thickness unevenness in the width direction
#Corona treatment was applied to the non-vapor deposited surface of the electrical-use stretched polypropylene film for vapor deposition of 0-pan paper, and aluminum was vapor-deposited on the vapor deposition surface.

Table 2 shows the results of evaluating the suitability for high-speed winding in which the material was wound into five strips with a width of 100 am.

At the same time, for comparison, the suitability for high-speed winding was evaluated in exactly the same manner as in Examples 3 and 4, except that no corona treatment was applied to the non-evaporated surface K11 of the stretched polypropylene film for electrical applications. The results are shown in Table 1-2. show.

The thickness unevenness in the width direction of the film shown in Table 2 was measured at KIO points in the width direction with a width of 520 sum using a dial gauge type micrometer, and the range of the maximum and minimum values was expressed.

According to the results in Table 2, even the comparative example 4 with relatively small thickness unevenness has poor one-winding suitability, whereas the samples of Examples 3 and 4 with large thickness unevenness have poor high-speed winding suitability. Since the results are good, the effect of the weak surface treatment on the non-evaporated surface is clear. Comparative Example 5 shows that winding suitability becomes even worse when the non-evaporated surface is surface-treated and the film has large thickness irregularities. ing.

As is clear from the results of the above Examples and Comparative Examples, the stretched propylene film for electrical purposes according to the present invention has a high Even when a film with uneven thickness is used, the slip property is controlled and it has excellent dual-speed winding suitability.

Patent applicant: Honshu Paper Co., Ltd.

Claims (1)

[Claims] (1) On one surface (deposition surface) that has been subjected to normal surface treatment,
In electrical polypropylene film used as a metallized film with metal vapor-deposited, one side (vapor-deposited side) that has undergone normal surface treatment and the opposite side (non-vapor-deposited side) have a wetting tension of 3.
3. A stretched polypropylene film for electrical use, characterized in that it has been surface-treated to d7ne15H or less. 2) Normal surface treatment is applied to the surface (evaporated surface) &C. The stretched polypropylene film for electrical use according to claim 1, which has a metal vapor deposited film.