JPH01151223A - Manufacture of both-face metallized film - Google Patents

Abstract

PURPOSE:To prevent a blocking phenomenon from being caused during a rewinding operation of a raw film by a method wherein, when aluminum is to be vacuum-evaporated onto both faces of a film whose surface wetting performance is little, a partial pressure of oxygen during an evaporation operation is set at a specific pressure. CONSTITUTION:A film is drawn from a roller 1 used to feed a raw film and is guided by using guide rollers 2; aluminum is evaporated onto one face at the surface of a first cooling can 3 from a crucible 4. Aluminum is evaporated onto the other face at the surface of a second cooling can 5 from a crucible 6; the film is taken up by a roller 7; these facilities are arranged inside a vacuum tank. During this process, a partial pressure of oxygen during an evaporation operation is set within a range of 4X10<-5>-2X10<-4>mmHg. As a result, close adhesion performance between aluminum evaporated films can be made extremely small as compared with close adhesion performance between the film and the sluminum evaporated film. By this setup, it is possible to prevent the evaporated film from being stripped off due to a blocking.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing double-sided metallized films by vacuum depositing aluminum on both sides of a plastic film.

Conventional technology Conventionally, this kind of plastic film for double-sided metallization has been made of polyethylene terephthalate (hereinafter referred to as PET).
is widely used. In addition, when aluminum is vacuum-deposited on both sides, the oxygen partial pressure is 1.2 x 10-5 ~ 2
X 10-5rraHg. In this way, even if a film with aluminum vapor-deposited on both sides is wound up and left as an original film, and then rewound several days later, there is almost no blocking between the vapor-deposited films. However, after vacuum-depositing aluminum on both sides of a polypropylene film, whose surface wettability is lower than that of PET, under the conditions described above, it is rolled up and left in its original state, and then rewound several days later.
The blocking between the deposited films is significant, making it difficult to put it to practical use.

Problems to be Solved by the Invention As mentioned above, there is no practical problem in double-sided vapor deposition of aluminum on PET film, which has a high surface wettability.
When aluminum is vapor-deposited on both sides of a film with low surface wettability, blocking occurs during unwinding of the film, making it difficult to put it to practical use. The present invention improves the method of double-sided vapor deposition of aluminum on a film with low surface wettability, such as a tld' polyolefin film, as described above.
This prevents blocking from occurring during unwinding of the original fabric.

Means for solving the problem When aluminum is vacuum-deposited on both sides of a film with low surface wettability such as polyolefin, the oxygen partial pressure at the time of deposition is set to 4 x 10-5 to 2 x 10-4 mmHg.
It is characterized by:

Oxygen partial pressure during evaporation is 4×10-5 to 2×10-'wHg.
By setting the value within this range, blocking will not occur at all when the film is left to stand for several days after being wound up after vapor deposition and then the original fabric for vapor deposition is rewound. By making the degree of vacuum during evaporation worse than in the conventional method, a sufficient aluminum oxide layer is formed on the surface of the evaporated film after evaporation, and the adhesion between the aluminum evaporation films is improved. This is significantly smaller than the adhesion, which prevents the deposited film from peeling off due to blocking. In addition, in a region where the oxygen partial pressure during vapor deposition is greater than 2×10 −'iw+H9, the formation of the aluminum vapor deposition film becomes extremely unstable, and the life of a crucible for melting the vapor deposited metal is shortened.

EXAMPLE FIG. 1 shows a schematic configuration of a vapor deposition apparatus. Reference numeral 1 denotes a roller for feeding out a film, and the film is guided by a guide roller 2, and aluminum is deposited from a crucible 4 on one surface of the first cooling can 3. Further, on the other surface of the second cooling can 6, aluminum is deposited from the crucible 6 and wound around the roller 7. These are placed in a vacuum chamber.

FIG. 2 shows how blocking occurs when the original vapor-deposited film is rewound. 8 is a film, 9.10 is a vapor deposited film, and in the rolled up state, the vapor deposited films 9 and 10 are in contact with each other. When this is rewound, one of the deposited films partially peels off from the film and adheres to the other deposited film, resulting in missing parts 9' and 10' of the deposited film.

Aluminum was vapor-deposited on a PET film and a polypropylene (hereinafter referred to as PP) film under various conditions using the vapor deposition apparatus shown in FIG. 1, and the period until blocking occurred and the incidence of wrinkles were compared. The results are shown in Table 1.

As shown in Figure 3, the wrinkle generation rate is determined by the width of the vapor-deposited original fabric 11 being L and the width of the wrinkles 12 generated at both ends being A.
1. When A2 is used, it is expressed as (A, +A2)/L×100.

(Note) Based on 1 JIS-e7es. The wettability of pp was changed by corona discharge treatment.

An additive having a melting point of 166° C. was used to prevent bleed-out of the additive due to vapor deposition.

Comparative Examples 1 to 5 in the table show the results of vapor deposition experiments conducted on PET films and PP films with different wettability under conventional vapor deposition conditions. Comparative Example 1 is a PET film with high wettability, so even if the oxygen partial pressure during vapor deposition is low, the number of days until blocking occurs is long. However, Comparative Examples 2 to 6
In the case of the PP film shown in , the surface wettability is similar to that of PET.
Because it is less dense than film, the number of days until blocking occurs is significantly shorter. However, as shown in Examples 1 to 4, the oxygen partial pressure during vapor deposition in the PP film was set to 4×10
-5 to 2×10 −′ mmHg increases the number of days until blocking occurs and reduces the wrinkle occurrence rate. In addition, the oxygen partial pressure during vapor deposition was set to 2 × 10-'mm.
If it is larger than Hg, the same performance as the above example can be obtained in terms of blocking properties and wrinkle generation, but there are problems such as the formation of the vapor deposited film becoming unstable and the life of the crucible for heating the vapor deposited metal being shortened. be.

In addition, although polypropylene film was used in the example,
A similar effect can be obtained if the film has a surface wettability of 43 dyne/crn or less.

Furthermore, the melting point of the additive for the PP film is not limited to 166°C.

Effects of the Invention As described above, according to the present invention, blocking properties and wrinkle generation rate are significantly improved, and double-sided aluminum vapor deposition of a film with low surface wettability such as a polyolefin film becomes possible. Therefore, when the aluminum double-sided vapor deposited film described above is applied to a capacitor, a significant cost reduction is realized.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the vapor deposition apparatus used in the examples, FIG. 2 is a schematic diagram showing how blocking occurs in a double-sided vapor deposited film, and FIG. 3 is a diagram illustrating the wrinkle occurrence rate.

Claims (1)

[Claims] In a method for producing a double-sided metallized film in which aluminum is vacuum-deposited on the front and back sides of a film with a surface wettability of 43 dyne/cm or less, the oxygen partial pressure during deposition is set to 4 x 10^-
A method for producing a double-sided metallized film, characterized in that the Hg is ^5 to 2 x 10^-^4 mmHg.