JPS6218448Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silicone coated plastic film.

Silicone-coated plastic film has superior surface smoothness, dimensional stability, heat resistance, transparency, and flatness compared to paper, which is the conventional base material.
Because of its high tensile strength, it has a wide range of uses, including not only as a substitute for release paper, but also for tightening the grips of fishing rods and golf shafts.
However, it is not easy to uniformly apply the silicone resin to the surface of the plastic film because of the insufficient wettability of the silicone resin to the plastic film and the static electricity charged on the plastic film. For example, when looking at the surface wetting properties of plastic films, which indicate how easily paints and inks get on them, polyester has a wettability of 38 to 45 dyne/cm, and polyolefin has a wettability of 38 to 45 dyne/cm.
32dyne/cm, 39-45dyne/cm for PVC (all according to JISK-6768), etc. On the other hand, the wetting properties of silicone resin vary depending on the type, but are 18 to 25 dyne/cm. Furthermore, the static electricity of the film itself and the distribution of frictional charges during processing are not uniform, and this static electricity tends to cause repelling phenomena, coating unevenness, or streaks.

These non-uniformities in the thickness of the silicone coating cause variations in peel resistance when it is used as a release paper. In order to solve this problem, various measures have been taken, such as selecting a silicone resin, devising the diluting solvent used, and removing static electricity from not only the film but also important parts of the coating equipment, but none of them have been able to achieve a satisfactory effect. Ta.

Another method was to use a film pre-contained with a non-metallic antistatic agent, but this method had poor adhesion between the film and the silicone, and the silicone was not applied after drying and curing. A smear that becomes cloudy when you rub the surface with your finger,
This causes rub-off, where the silicone coating falls off.
Furthermore, it has been found that some combinations of silicone resin and antistatic agent have defects that cause curing inhibition.

Another possibility is to apply an antistatic agent to the surface that is not coated with silicone, but this may cause the antistatic agent to migrate and impair the coating properties of the silicone.
It has the disadvantage that it reduces the inherent properties of silicone or deteriorates over time.

The present invention improves the adhesion between the silicone resin and the film by providing a conductive layer such as a metal thin film layer on the surface of the film, dissipating static electricity generated on the surface or inside the plastic film, and eliminating local charging. This invention relates to a silicone-coated plastic film in which a silicone resin is coated uniformly and beautifully on the film.

The silicone-coated plastic film according to the present invention has the following characteristics: (1) Since static electricity is difficult to generate, there are no coating defects such as repellency, uneven coating, or streaks, and the silicone resin can be applied uniformly. In addition, even if coating processing is performed at high speed, these drawbacks are small.

(b) Since the silicone resin is applied uniformly, the films do not stick to each other, making them easy to handle.

C. There is little variation in peeling resistance when used as a mold release material.

(d) Since it is based on metal vapor deposition, etc., there is little change over time, and the resistance value can be easily controlled.

etc. can be mentioned.

To explain the structure with a diagram, as shown in FIG. 1, a silicone resin layer 1 is formed on one side of a plastic film 2, and a thin film of metal, metal alloy, metal oxide, carbon, etc. is formed on the other side. Alternatively, a conductive layer 3 made of a resin layer containing these powders is provided so that the surface resistance is 10 ¹³ Ω or less, preferably 10 ⁸ Ω or less, or a conductive layer 3 is provided on one side of the plastic film 2 as shown in FIG. As in the case of FIG. 1, a conductive layer 3 such as a metal thin film is provided, and a silicone resin layer is provided on the surface of the conductive layer.

The plastic film used in the present invention may be any film made of polyester, polyolefin, polyamide, or the like, or may be a composite of these or other plastics. Further, this film may contain a plasticizer, a coloring agent, a slip improver, etc., as necessary, to the extent that it does not interfere with conductive layer processing such as vapor deposition and silicone resin processing. Moreover, one having a roughened surface on one or both sides can also be used.

The conductive layer may be made of various metals, alloys, metal oxides, etc. that have electrical conductivity, or carbon, etc. Examples of the first three include thin films of aluminum, zinc, chromium, nickel, iron, silver, palladium, copper, tin, antimony, copper alloys, nickel alloys, tin oxide, titanium oxide, indium oxide, etc., with aluminum being the most common.

Various methods such as vacuum evaporation, sputtering, and ion plating are used to provide these conductive layers. Furthermore, a blend of these powders in a resin may be applied. The thickness of the conductive layer formed by metal vapor deposition varies depending on the material, but is usually about 0.01 to 0.2 microns.
If transparency is required, in a region with a thickness of several tenths of the above lower limit or more, the surface resistance should be 10 ¹³ in relation to the required electrostatic properties.
An appropriate thickness of Ω or less, preferably 10 ⁸ Ω or less, is determined based on the relationship with the specific resistance of the material.
In addition, if a metallic luster is required for the appearance, use a material with a metallic luster and a thicker material; conversely, if a translucent material is required, or if transparency is required, a thinner material is used. , use something that has transparent properties. That is, the conductive layer to be used may be selected based on the electrical properties and optical properties specific to the material.
When coating with a resin containing metal powder or carbon particles, the thickness is usually 1 to 2 microns.
Note that the surface resistance is measured using, for example, a super megohmmeter manufactured by Yokogawa Electric under conditions of 20°C and 65% RH.

In some cases, a protective layer may be provided to protect the metal layer, etc., and an appropriate one is selected from thermoplastic or thermosetting resins. When a silicone coat layer is provided on the metal layer, the protective layer may be omitted.

The silicone resin may be either a condensation reaction type or an addition reaction type, and each type is selected from among a solvent type, an emulsion type, and a solvent-free type. In reality, solvent types are often used due to productivity, economy, performance, etc. A coloring agent, an antifoaming agent, a dispersing agent, etc. may be added to the silicone resin. In addition, the coating amount of the silicone resin layer varies depending on the application, but the silicone resin solid content is 0.005
A range of ~5 g/ ^m2 is preferred.

The silicone-coated plastic film of the present invention can be satisfactorily used as a base film for casting carriers such as ceramic capacitors which require extremely high precision. It goes without saying that it has extremely good performance in other uses, and is also effective as a separator for general adhesives. In particular, when used as a release paper during the production of multilayer capacitors made from ceramic sheets, there is no peeling charge during release and no dust is trapped. It has the same effect when used as a release paper when manufacturing plywood, etc.

Examples will be described below.

Example A After processing aluminum to a thickness of 500 angstroms (surface resistance 0.5Ω/□) by vacuum evaporation on one side of a commercially available polyester film (Lumirror, manufactured by Toray Industries, Inc., thickness 25 microns), the other side was That is, a 5% solution of KS-774 manufactured by Shin-Etsu Silicone Co., Ltd. as a silicone resin was applied to the non-evaporated surface using a Meyer bar No. 5 at a coating amount of 70 g/m ² (wet).

An extremely uniform silicone resin layer was formed, with no repellent coating unevenness or streaks. For comparison, a polyester film without an aluminum vapor-deposited layer was tested, and there were many slight repellents and streaks in the coating of the silicone resin.

When this paper was used as a release paper in the molding process of plywood and decorative laminates, there was almost no charge during peeling, and there was no entrainment of dust or the like.

Example B Ni-Cr alloy (Ni80%, Cr20
%) thin film was made. The surface resistance of the thin film is approximately 200
Ω/□. This metallized film was coated with SRX244 manufactured by Toray Silicone Co., Ltd. as a silicone resin to a thickness of 0.1 micron. An extremely uniform silicone film was formed on both the non-metallic and metallic surfaces.

Example C A thin layer of aluminum was vacuum-deposited on one side of biaxially oriented polypropylene (manufactured by Nimura Sansho Kagaku Co., Ltd., thickness 25 microns) to give a light transmittance of 35%.
(Surface resistance value: 10 ³ Ω/□) The silicone resin of Example A was applied to the back surface by squeeze coating. Even in high-speed coating (50 to 200 m/min), a uniform coated surface was obtained, and a high-quality product for adhesive release paper was obtained.

Example D A linear polyester resin (Vylon 20S, Toyobo Co., Ltd.) containing acetylene carbon was applied to the surface of a 25 micron PET film. The thickness was adjusted so that the surface resistance was 10 ³ to 10 ⁵ Ω/□. Then, KS-834 manufactured by Shin-Etsu Silicone Co., Ltd. was applied as a silicone resin to the other surface to obtain beautiful uniform silicone. Note that this structure can also be used as a protective packaging material for electronic components.

Example E Indium oxide was deposited using a vacuum evaporation method to achieve a surface resistance of 10 ⁵ ~
10 ⁸ Ω/□, PET with light transmittance of 70-90%
It was processed into a film (50 microns thick). The silicone of Example D was processed as a layer of silicone resin on the back side, and the processing speed and finish were extremely satisfactory, and since indium oxide was used as the conductive layer, an extremely transparent product was obtained. Ta.

[Brief explanation of the drawing]

1 and 2 are enlarged schematic cross-sectional views of the silicone coated plastic film of the present invention. 1... Silicone resin layer, 2... Plastic film, 3... Conductive layer.

Claims (1)

[Scope of utility model registration request] A conductive layer made of a thin film of metal, metal alloy, metal oxide, carbon, etc., or a resin layer containing powder of these is provided on the surface, and the surface resistance is set to 10 ¹³ Ω/□ or less, and the opposite surface is , or a plastic film with a silicone resin layer provided on the conductive layer.