JP2663594B2 - Polypropylene film for capacitor evaporation - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polypropylene film for vapor deposition for capacitors.

[Conventional technology]

Polypropylene films are widely used as industrial materials because of their excellent properties. In recent years, with the change in market requirements and various improvements, the use of vapor-depositing a metal on a polypropylene film has been rapidly increasing. Above all, the transition to vapor deposition is remarkable for capacitors, because they can be reduced in size and can be provided with self-healing properties as compared with those wound with a conventional metal foil. For this reason, in addition to the prior art, good vapor deposition workability has been required.

However, polypropylene film is weaker than polyester film and polyimide film,
It is not suitable for vapor deposition because of poor dimensional stability against heat. Therefore, in the actual situation, the processing is performed while finely adjusting the processing conditions such as the tension and the cooling temperature during the vapor deposition processing. At this time, if the appropriate conditions are removed, various vapor deposition defects such as heat loss, wrinkles, and uneven density are caused, and the processing yield is reduced.

[Problems to be solved by the invention]

That is, the point in the vapor deposition processing of the polypropylene film is how the polypropylene film is closely adhered to the cooling roll facing the vapor deposition source without distortion.
To improve the cooling effect of the entire surface.

However, even if the tension condition is pursued, sufficient adhesion cannot be obtained because the slip between the polypropylene film and the cooling roll is poor, and precipitates from the polypropylene film are deposited on the cooling roll and significantly reduce the cooling effect. There were drawbacks.

The present invention has been made in view of the above problems, and has as its object to provide a polypropylene film which is excellent in slipperiness with a cooling roll, has few precipitates, and is excellent in vapor deposition workability.

[Means for solving the problem]

The polypropylene film for vapor deposition for a capacitor of the present invention is composed of a non-deposited surface after metal vapor deposition on one surface of the polypropylene film and a chromium-plated metal plate.
The coefficient of static friction at ℃ is 0.8 or less and the melting point is 1
It is characterized in that the content of the additive at 30 ° C. or lower is 4000 ppm by weight or less.

If the coefficient of static friction exceeds 0.8, the film does not slip on the cooling roll, does not fit even when tension is applied, the film partially rises from the cooling roll, and it is easy to cause wrinkles and uneven shading, which is inappropriate. is there. Preferably it is 0.7 or less, more preferably 0.6 or less.

The state of the precipitate on the chill roll depends on the additives in the polypropylene film, and for capacitors, the content of additives having a melting point of 130 ° C. or less is 4000 wt ppm.
If it exceeds, the cooling effect due to the precipitates is remarkably reduced, the amount of heat received by the film at the time of vapor deposition increases, and disadvantages such as heat loss occur, which is unsuitable. Preferably 3000 ppm by weight
Or less, more preferably 2,000 ppm by weight or less.

Here, as an additive having a melting point of 130 ° C. or less, tetrakis [methylene-3 (3,5-di-tert-butyl-4hydroxyphenyl) propionate] methane,
2,2'-methylene-bis (4-methyl-6-tert-butyl-phenol, η-octadecyl-3-
(4'-Hydroxy-3 ', 5'-di-tert-butyl-phenyl) propionate, 2,2-thio [diethyl-bis-3 (3'-5-di-tert-butyl-4)
-Hydroxyphenyl) propionate].

F-10 in the length direction of the polypropylene film of the present invention
The 0 value is not particularly limited, but is preferably 10 kg / mm ² or more from the viewpoint that the stiffness is such that it cannot be stretched by the processing tension.

The method for producing the polypropylene film of the present invention is not particularly limited, and may be an ordinary stretching method, preferably biaxial stretching, but may be uniaxial stretching. Of course, an inflation method or a tenter method may be used.

Further, the polymer used in the polypropylene film of the present invention is, in addition to homopolymer, propylene and other α
-It may be a copolymer of olefins (eg, ethylene, butene, etc.) or a blend of polypropylene and another α-olefin polymer (eg, polyethylene, polybutene, etc.).

Next, an example of the method for producing the polypropylene film of the present invention will be described. However, it is not limited to the following production method.

Tetotax [methylene-3 (3,5-di-tert-butyl-4hydroxyphenyl) propionate]
Methane added II (isotactic index)
96% or more of polypropylene resin is melted at a temperature of 190-280 ° C and extruded into a sheet from a slit T die.
Cool and solidify with a chill roll at 30-95 ° C. Next, 120-160
Stretched 3 to 7 times in the longitudinal direction at a temperature of 150 ° C., and then 145 to 165
Stretched 5 to 12 times in the width direction at a temperature of 150 ° C, and 150 to 165
Heat treatment at a temperature of ° C. Then, the surface to be vapor-deposited is subjected to a surface treatment such as a corona discharge treatment so as to have a wet tension of 35 to 47 dyne / cm, and is wound by a winder.

Here, the coefficient of friction with a metal plate at a high temperature, for example, 80 ° C., is related to the properties of the polypropylene film as follows. The friction coefficient increases as the surface roughness of the surface in contact with the metal plate decreases, as the wet tension of the surface in contact with the metal plate increases, and as the amount of the low melting point additive increases.

In depositing the polypropylene film of the present invention, the metal to be deposited is not limited, but is preferably aluminum (Al), zinc (Zn), or a mixture or alloy thereof.

Further, the vapor deposition surface may be one side or both sides.

Next, the measurement method and the evaluation method used in the present invention will be described.

(1) Coefficient of static friction between the non-deposited surface and the metal plate at 80 ° C. A rectangular film sample having a length of 100 mm and a width of 75 mm is collected. Next, Al was deposited on the surface for metal deposition.
Deposit to a thickness of 20-40 nm. Next, the deposited film is set so that the non-deposited surface is in contact with a metal hot plate plated with chromium (Cr). A 200 g load is placed on this sample so as to apply a rectangular area of 65 mm in the length direction and 63 mm in the width direction. Thereafter, the temperature of the hot plate is raised to 80 ° C., the vapor-deposited film is pulled at a speed of 150 mm / min in the length direction, and its maximum static resistance value (g) is read.

Static friction coefficient = maximum static resistance value / 200 In the above equation, 200 in the denominator is a load (g).

 The number of measurements is set to 3, and the average value is obtained.

(2) Quantification of additives Cut the film into small pieces of 5 mm x 5 mm or less, and collect 8 g. Next, the sample was heated at 65 ° C. and 50 ml of chloroform for 90 minutes.
After extraction for 1 minute, this solution is subjected to suction filtration and further suction filtration while washing with chloroform. Thereafter, chloroform is recovered and the extract is dried. Next, this extract is diluted to 100 ml with methanol. 2 ml of this solution was collected and subjected to liquid chromatography (Shimadzu “Shimadzu High Performance Liquid Chromatograph LC-4A” and “Chromatopack C”).
-R2A (X) "), and determine the concentration (mg / ml) using the calibration curve previously determined. From the concentration thus determined, the content is determined by the following equation.

In the above formula, 100 of the molecules is the volume of the methanol solution (ml),
The denominator 8000 is the weight (mg) of the sample.

〔Example〕

 Next, a description will be given based on an embodiment of the present invention.

Example 1 Tetrakis [methylene-3 (3,5-di-tert-butyl-4hydroxyphenyl) propionate]
II97% propylene homopolymer to which methane was added at 500 mmp was fed to a 260 ° C. extruder, extruded from a slitted T-die, cooled and solidified by a chill roll at 80 ° C., and then cooled at 135 ° C. in the length direction at a temperature of 135 ° C. Stretched twice and then 16 times in the width direction.
The film was stretched 8 times at a temperature of 0 ° C. and further heat-treated at a temperature of 160 ° C. Next, a wet tension of 39 dyne / cm on one side of the film
And then wound with a winder. The film thickness at this time was 8 μm.

Next, this film was slit into a width of 630 mm and a length of 25000 m, and the vapor deposition workability was evaluated.

The deposition process was carried out using a ULVAC evaporator with a 630 mm width, Al specification, with a 25 nm Al film thickness, a transport speed of 250 m / min, an unwinding tension of 4 kg, a winding tension of 4 kg, and a cooling roll refrigerant temperature of -15 ° C. And
Evaporation workability was determined according to the following criteria.

(1) Unevenness of density of deposited film A: No unevenness of density.

：: Practical possible, though there is partial shading.

×: Unevenness in the entire surface, impractical.

(2) Heat loss ：: None at all.

：: Heat loss, but slight, practical.

X: Heat loss is severe, and practical use is impossible.

(3) Wrinkles The film after evaporation is divided into six 100mm widths in the width direction.
After sliding for 5 minutes in the length direction to a length of 500 m, a total of 30 reels were judged as pass / fail, and the number of defective reels was judged as follows.

：: Number of defective rails 1 or less 以下: Number of defective reels 2 to 4 ×: Number of defective reels 5 or more The results are shown in Table 1.

The results are shown in Table 1 of Examples.

Example 2 Tetrakis [methylene-3 (3,5-di-tert-butyl-4hydroxyphenyl) propionate]
Same as Example 1 except that the amount of methane added was 3500 ppm. The results are shown in Table 1.

Example 3 Tetrakis [methylene-3 (3,5-di-tert-butyl-4hydroxyphenyl) propionate]
Instead of methane, 1,3,5 trimethyl-2,4,6-tris (3,
Except that 5000 ppm of 5-di-tert-butyl-4hydroxybenzyl) benzene (melting point: 244 ° C.) was added,
Same as Example 1. The results are shown in Table 1.

Example 4 Same as Example 1 except that the added amount of 1,3,5 trimethyl-2,4-6-tris (3,5-di-tert-butyl-4hydroxybenzyl) benzene was 2000 ppm. The results are shown in Table 1.

Comparative Example 1 Tetrakis [methylene-3 (3,5-di-tert-butyl-4hydroxyphenyl) propionate]
Same as Example 1 except that the amount of methane added was 5000 ppm. The results are shown in Table 1.

Comparative Example 2 The same as Example 2 except that the temperature of the chill roll was set to 30 ° C. and the mixture was cooled and solidified. The results are shown in Table 1.

Comparative Example 3 Wet tension of 43 dyne on both sides of polypropylene film
The same as Example 1 except that the corona discharge treatment was performed so as to be / cm. The results are shown in Table 1.

Comparative Example 4 Tetrakis [methylene-3 (3,5-di-tert-butyl-4hydroxyphenyl) propionate]
Same as Example 1 except that the addition amount of methane was 6000 ppm and the wetting tension was 35 dyne / cm. The results are shown in Table 1.

[Effect of the Invention] In the polypropylene film of the present invention, three defects such as uneven shading, heat loss, and wrinkles hardly occur in the vapor deposition processing, and a contact film capacitor can be obtained with a high processing yield.

Claims (1)

(57) [Claims] 1. A coefficient of static friction at 80.degree. C. between a non-deposited surface of a polypropylene film after metal deposition on one surface and a chromium-plated metal plate and a melting point of 130.degree. C. or less. Wherein the content of the additive is 4,000 ppm by weight or less.