JPS5973942A - Surface protective material - 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 a surface protective material, and particularly provides a protective material suitable for solar cells and the like that require moisture resistance.

As a solar cell, for example, one in which amorphous silicon, a transparent electrode, and a glass plate as a surface protection material are laminated in sequence on an aluminum electrode is known. However, in conventional solar cells, the glass plate is damaged. Not only is it easy to use, but the sealing between the glass plate and the transparent electrode is not necessarily sufficient, and there are problems with moisture resistance.

The present invention relates to a surface protection material that solves the above-mentioned problems of the prior art, and comprises a 75x high-frequency sputter-etched surface of a 7-layer resin film, and a melt adhesive layer is formed on the treated surface. It is.

The fluororesin Noylrem used in the present invention is a tetrafluoroethylene-hexafluoro-cobylene co-M polymer (F
EP), chlorotrifluoroethylene polymer (0T
FE), ethylene-tetrafluoroethylene copolymer, etc. are suitable, and the thickness is usually about 25 to 3
00μ is used.

In the present invention, the surface of the above-mentioned resin film is subjected to high frequency sputter etching treatment (hereinafter referred to as F Sunokunota etching treatment).

This sputter etching process involves applying a high frequency voltage between cathode and anode electrodes in a reduced pressure atmosphere in a pressure-resistant container, accelerating the cations generated by the discharge in the dark part of the cathode where the sulfur energy is large in the discharge area. This is a process in which the fluororesin film (above) is collided with the surface of the rem. This device (details will be described later) has a cathode and an anode facing each other in a pressure-resistant container, the cathode is connected to a high-frequency power source via an impedance matching device, and the anode is connected to the ground side of the high-frequency power source. A shielding electrode is provided on the outside of the cathode and maintained at ground potential. A fluororesin film can be subjected to the anodic treatment using such an apparatus in either a batch or continuous manner.

In the present invention, in order to stably perform the spano-etching treatment on the fluororesin film, the atmospheric pressure is usually 0.005 to 0.5 Torr, preferably 0.05 to 0.5 Torr.
It is preferable to set it to 0.21'orr.

Further, the discharge processing amount, that is, the product of the discharge power (W/ci) and the processing time (sea) is set to be equal to or more than l WSec/c+y/, preferably from 10 to 4 (l W-5ec10+/).

The discharge power and treatment time can be set in any way as long as the amount of discharge treatment exceeds the above predetermined value, but from a practical standpoint, the discharge power is usually O11 to 5 W/cm, preferably 0.
．． The processing time is usually set within the range of 1 to 3 (river sand) within the range of 2 to 2 v.

Furthermore, as a high frequency power source used for sputter etching processing, a power source with a frequency of several hundred KHz to several MHz (7) can be used, but in practice, the industrially allocated frequency of 13.56 is used.
It is preferable to use a MHz power source. Various gases can be used as the atmosphere gas, but inert gases such as argon and helium, nitrogen gas, carbon dioxide gas, water vapor, etc. are preferable.

Next, an example of sputter etching treatment for a fluororesin film in the present invention will be explained with reference to the drawings. In the drawing, 1 is an exhaust pipe connected to a vacuum pump (not shown) for exhausting gas in the reduced pressure container 2, 3 is a valve for introducing atmospheric gas into the reduced pressure container 2, and 4 is a valve for introducing atmospheric gas into the reduced pressure container 2.
is the second electrode for sputter-etching the surface of the fluororesin film 5, which is electrically insulated from the vacuum container 2 and connected to an external matching box 6 (impedance matching device) using an airtightly sealed lead wire. 08, which is connected and further led to the high frequency power source 7, is a shielding electrode of the electrode 4, and is electrically connected to the ground 9 of the high frequency power source 7.

IO is a counter electrode and is also connected to the ground side of the high frequency power source 7.

The reduced pressure container 2 serves to keep the atmospheric pressure constant, and if a metal reduced pressure container is used, it is connected to the ground side of the high frequency power source 7.

The matching box 6 is a circuit made of capacitance and inductance, and performs impedance matching.

In order to sputter-etch the surface of one side of the film 5 corresponding to the counter electrode 10, the pressure inside the reduced pressure container 2 is reduced using a vacuum pump, and while atmospheric gas is introduced from the pulp 3, the pressure inside the container 2 is adjusted to a predetermined atmospheric pressure. ,after that,
When a voltage is continuously applied from the high frequency power source 7 for a predetermined period of time under a predetermined atmospheric pressure while introducing an atmospheric gas, the surface of one side of the film 5 is gradually treated with scorch and proboscis.

Note that the electrode 4 and the counter electrode 10 generate heat due to discharge,
As the temperature rises, a cooling passage is installed inside it,
It is preferable to circulate a cooling liquid or gas.

When the surface of the fluororesin film is sputter-etched in this manner, countless fine needle-like protrusions are formed on the treated surface.

According to the present invention, a hot-melt adhesive layer containing ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc. as a main component is formed on the sputter-etched surface of the heptad resin film.

When the surface protection material of the present invention is applied to applications requiring transparency such as a preservation material for solar cells, the light transmittance (measured according to JIS-671411) should be 9.
It is preferable to set the coefficient to 0 or higher.

The adhesive force between the fluororesin film and the hot melt adhesive in the surface protection material of the present invention is due to the fact that the fine sword-like protrusions formed on the surface of the film by sputter etching exert an anchoring effect on the adhesive. Therefore, it becomes large.

It has been revealed that when the surface protection material of the present invention is adhered to the transparent electrode of a solar cell using a hot melt adhesive layer, the life of the cell can be extended.

The reason for this is not necessarily clear, but since the hot melt adhesive f\11 layer is firmly bonded to the transparent electrode, the sealing performance in this field is excellent.
As mentioned above, the adhesive force between the fluorine (iit I finger I Rem and the hot melt adhesive layer l/bond) is great, and the sealing properties of this interface are also excellent, making it almost moisture-proof to the surface of the battery. It is inferred that this is because moisture is blocked on the battery surface and prevented from reaching the inside, and the transparent electrode and amorphous/licon are protected from moisture. For example, it is useful as a protective material for solar heat collectors, solar selective absorption films, etc.

The present invention is constructed as described above.) Since a hot melt adhesive layer is formed on the sputter-etched surface of the base resin film, the adhesive strength between the two is strong, the sealing property at this interface is perfect, and the It has the characteristic that it can be suitably used as a surface protection agent for items that require a high degree of moisture resistance, such as in cities and ponds.

The present invention will be explained below with reference to Examples.

Example 1 A transparent FEP film with a thickness of 100 μm was placed on the electrode 4 of the apparatus shown in FIG.
Open the chamber, introduce water vapor, and adjust and maintain the atmospheric pressure at 01 TOrr.

Next, a high frequency voltage of 13.56 MHz is applied from the high frequency power supply 7 between the electrode 4 and the counter electrode 10, and one surface of the film is sputter etched for 2 seconds at a discharge power of 0.5 W/cm.

After that, a 30 μm thick layer of ethylene-ethyl acrylate copolymer (manufactured by Nippon Unicar Co., Ltd., trade name: EEA6169) was applied to the sputter-etched surface of the F”BP film.
A hot melt adhesive layer was formed to obtain a surface protection material (sample number 1) with a light transmittance of 95%.

This surface protection material was applied to the north of the transparent electrode of a solar cell in which transparent electrodes consisting of an aluminum electrode, amorphous silicon, and a thin film of tin oxide were sequentially laminated at a temperature of 120°C and a pressure of 5 kg/cm.
Heat and pressure was applied for 3 minutes under the conditions of
The moisture-proof performance of the battery was examined by leaving it in an atmosphere of 90% RE.

This moisture-proofing performance can be determined by measuring the half-life of the light conversion efficiency of the solar cell, and the half-life of the solar cell using the surface protection material of sample number 1 was 3500 hours, and the half-life was 3500 hours. Separately, Table 1 shows the sputter etching processing conditions.
The surface protective materials of Sample Nos. 2 to 4 were obtained in the same manner as Sample No. 1 except for the changes shown in the table, and these surface protective materials were applied to solar cells in the same manner as above to examine the moisture-proof performance. The results are shown in Table 1.

For comparison, the half-life of the light conversion efficiency was measured in a solar cell in which a glass plate with a thickness of 0θμ was adhered to a transparent electrode using polyvinylbunaral resin. 2
It was 500 hours.

Table 1 Example 2 Transparent C with a thickness of 200μ! While introducing water vapor to one side of the TFE sheet, the atmospheric pressure is 0.1 Torr, and the discharge power is 1.
Suhanota etching treatment for 30 seconds under the condition of Vσ〆0 Then, C! An ethylene-vinyl acetate copolymer with a vinyl acetate content of 19% by weight (manufactured by Mitsui Polychemical Co., Ltd., trade name +1907) was applied to the sputter-etched surface of the TFE sheet.
) to obtain a surface protection material with a light transmittance of 91%.

This surface protective material was adhered to the transparent electrode in the same manner as in Example 1, and the moisture-proof performance of this battery was examined.
The half-life of solar conversion efficiency was 4500 hours.

As is clear from the above Examples and Comparative Examples, the surface protection material of the present invention has poor moisture resistance, and it can be seen that when this surface protection material is applied, the life of the solar cell can be significantly extended.

[Brief explanation of the drawing]

The drawing is a schematic view showing an example of an apparatus for subjecting the surface of a fluororesin film to a scratching process for use in the present invention. 2...Reduced pressure container 4...Electrode 5...Fluororesin film 7...High frequency power source 1o-...Counter electrode Patent applicant Sanbe Hijikata, representative of Nitto Electric Industry Co., Ltd.

Claims (1)

[Claims] F. A surface protection material in which the surface of a base resin film is subjected to high frequency sputter etching treatment, and a hot melt adhesive layer is formed on the treated surface.