JPH025173B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a composite sheet having a laminated structure, in which a sheet made of fluororesin is an essential constituent material, and any other sheet-like material is adhered to this sheet. (In this specification, the term "sheet" is used to include a thin film with a thickness of less than about 0.2 mm, which is often referred to as a "film.")

Fluorine resin sheets exhibit excellent performance in terms of electrical properties, thermal properties, chemical resistance, gas barrier properties, etc. However, on the other hand, because the sheet surface is inert, they are not compatible with other plastic products. metal,
The disadvantage is that it is difficult to bond firmly with paper, cloth, etc. For this reason, when it is necessary to adhere a fluororesin sheet to another material, great pains have conventionally been taken. For example, there is a method in which the surface of a fluororesin sheet is treated with a liquid ammonia solution of naphthalene, and then another plastic film, which will become an adhesive layer, is pressed in a molten state. Not only does it require a high degree of care when handling, but it also has the drawback of turning the treated surface brown, lowering its commercial value, and significantly deteriorating its electrical properties (especially insulation). In addition, there are methods to improve the adhesion of fluororesin sheets by applying plasma treatment to the surface or sputtering etching treatment using this method, but in addition to requiring large and expensive treatment equipment,
There are also problems in terms of productivity and uniformity of processing effects. When the fluororesin is trifluorovinylidene chloride resin, immediately after corona discharge treatment, a mixture of a methyl alcohol solution of a reactive epoxy resin and an anhydrous alcohol solution of polyethyleneimine is applied, and then a polyolefin resin is applied. A method of thermocompression bonding using a film as an adhesive layer is also known, but
The fluororesin sheet composite obtained by this method not only has insufficient adhesive strength between the fluororesin sheet and the polyolefin resin film, but also has poor water resistance.
Therefore, strong water-resistant adhesion cannot be expected, so it can only be used for extremely limited purposes (needless to say, when the adhesive strength between the base material and the adhesive layer is weak, the adhesive Strong adhesion cannot occur because force dominates the bond strength between the substrate and other materials.)

The purpose of the present invention is to solve the above-mentioned adhesion problem and to enable more diverse uses of the fluororesin sheet by firmly adhering the fluororesin sheet to any other sheet-like material. The object of the present invention is to provide a method for easily manufacturing a composite sheet with a high temperature.

The present invention has succeeded in achieving this objective.
When manufacturing a composite sheet made by adhering another sheet-like material to one or both sides of a fluororesin sheet, the surface of the fluororesin sheet to be adhered to the other sheet-like material is subjected to corona discharge treatment. The surface wetting tension is 35 dynes/cm or more, and the molten ethylene
Each sheet is made by overlapping and pressing the above-treated fluororesin sheet and the sheet material to be bonded through a thin film of glycidyl methacrylate-vinyl acetate ternary random copolymer (hereinafter referred to as EGV resin). It is characterized by being integrated and then heat-treated under tension.

EGV resin is commercially available from Sumitomo Chemical Co., Ltd. under the trade name Bond First as a reactive hot melt adhesive. Its characteristics are that it has good water resistance and solvent resistance, and can be used to bond many materials such as polyolefins, metals, textile products, synthetic rubber, inorganic materials, and wood. However, if this resin is used simply as a hot-melt adhesive, it will not have the ability to bond ordinary fluorocarbon resin sheets, so we decided to use this resin to manufacture composite sheets made of fluorocarbon resin sheets. There are no successful examples. Adhesion of fluororesin sheets with EGV resin becomes possible for the first time when the above-mentioned physical treatment is used in combination.

When producing a composite sheet by the method of the present invention, the EGV resin preferably has a melting point of about 90 to 98°C and a copolymerization ratio of glycidyl methacrylate of about 3 to 15 mol%. All of the commercially available products such as BOND FAST grades 2A, 2B, E, 7A, 7B, etc. can be used as they are, but among them, BOND FAST is particularly suitable for manufacturing the composite sheet of the present invention. It is strike 7B.

On the other hand, the surface of the fluororesin sheet that is to be coated with the EGV resin must be subjected to a corona discharge treatment in advance. That is, it is treated according to the well-known corona discharge treatment as a pretreatment for adhesion or printing of polyolefin films, etc., and is brought into an excited state where the surface wetting tension is preferably 35 dynes/cm or more. Other than the need for such pre-treatment, there are no restrictions on fluororesin sheets, and polymers of various fluorine-based monomers such as trifluoroethylene and hexafluoroethylene, or these monomers and olefins. Any sheet made of a copolymer or the like can be used. Further, the fluororesin sheet may contain a filler such as molybdenum powder, bronze powder, graphite, or a pigment. Note that the thickness is not particularly limited.

The fluororesin sheet that has undergone corona discharge treatment is immediately sent to a lamination device equipped with an EGV resin melt extruder, and the corona discharge treated surface is used as the adhesive surface to adhere the thin film of EGV resin, which is still in a molten state immediately after extrusion. The sheet is pressure-bonded to other sheets to be bonded using the so-called sand-deutsche lamination method, which uses a layer of adhesive. This step may be carried out in accordance with the general Sand-German tylaminate method. However, if the sheet to be adhered to the fluororesin sheet is a thermoplastic resin, the material resin may be coextruded with the EGV resin to be integrated with the EGV resin layer in advance. If the coextrusion method is not used,
No special pretreatment is required for the adhesive surface of the sheet that will be adhered to the fluororesin sheet, but if necessary, pretreatment to increase affinity with the EGV resin, such as applying an anchor agent treated with corona discharge, may be necessary. You may also apply

When adhering other sheet-like materials to both sides of the fluororesin sheet, the untreated surfaces are then subjected to corona discharge treatment and adhesion treatment similar to those described above.

The interlayer adhesive strength of the composite sheet obtained by cooling to room temperature after pressure bonding is still extremely weak, and the bonded sheets can be easily peeled off by hand. This is because the adhesive force between the fluororesin layer and the EGV resin layer is weak. However, after this, at a temperature of about 20°C or higher for about 24 to 48 hours or more,
When maintained under a tension of approximately 10 to 15 g/cm, the excited surface of the fluororesin sheet reacts with the epoxy groups in the EGV resin, and the epoxy groups open to form crosslinks. The adhesive force between the fluororesin layer and the EGV resin layer increases significantly. As a result, the adhesive layer made of EGV resin exhibits adhesive strength higher than the normally required level, and the adhesive strength between the bonded sheets is dominated by the adhesive strength between the fluororesin layer and the EGV resin layer. But usually 400
A composite sheet with a peel strength (measured by a 180° peel test) of at least g/15 mm can be obtained.

When performing the above-mentioned tensioning treatment, the sheet does not need to be in an elongated state, and can be performed in a rolled-up state. The effect of this treatment will appear in a shorter time as the treatment temperature is higher, but if the temperature is too high, undesirable results such as blocking will occur if the treatment is carried out in a rolled state, so it is usually carried out at a temperature below 50℃. desirable.

According to the composite sheet manufacturing method of the present invention as described above, sheets made of plastics such as polyolefin, polyester, polyamide, polyimide, ethylene-vinyl acetate copolymer, etc., metal foils such as aluminum foil, various other textile products, and paper. A composite sheet can be made by firmly adhering various sheet-like materials such as synthetic rubber sheets and fluororesin sheets.
The resulting adhesive structure has adhesive strength sufficient for practical use, as well as excellent water resistance and solvent resistance. Furthermore, the fluororesin layer retains its original excellent properties. Therefore, with the present invention, fluororesin sheets can now be easily used in many fields where the excellent properties of fluorocarbon resin sheets could not be utilized due to difficulty in adhesion. The effects of implementing the present invention are quite remarkable.

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

Example 1 A polyvinyl fluoride resin sheet having a thickness of 0.2 mm was supplied to the discharge gap of a corona discharge treatment device at a speed of 20 m/min for treatment. The wetting tension of the surface before treatment is 32
Dynes/cm, after treatment it was 40 dynes/cm.

On the other hand, EGV resin Bondfast 7B and polypropylene resin Sumikasen F705 were extruded at a ratio of 1:1.5 from a T-die coextrusion laminator having an opening slit of 0.7 mm to form a laminated sheet with a thickness of 250 microns. Then, while it is still in a molten state, it is pressed onto the treated surface of the corona discharge-treated fluororesin sheet with the EGV resin layer inside, and then cooled with a cooling roll, and then
It was wound under a constant tension of 10 g/cm. The obtained composite sheet in a wound state was then placed in a heat insulating tank at 45° C. and allowed to stand for 12 hours. The peeling resistance between the fluororesin layer and polypropylene resin layer of the composite sheet after treatment is
It was 850g/15mm.

Claims (1)

[Claims] 1. In manufacturing a composite sheet formed by adhering another sheet-like material to one or both sides of a fluororesin sheet, the fluoro-resin sheet is adhered to another sheet-like material. The surface is treated with a corona discharge to have a surface wetting tension of 35 dynes/cm or more, and the fluororesin sheet after the above treatment is passed through a thin film of molten ethylene-glycidyl methacrylate-vinyl acetate ternary random copolymer. A method for producing a composite sheet, which comprises stacking and pressing sheet materials to be bonded together to integrate each sheet, and further subjecting the sheets to tension treatment. 2. The manufacturing method according to claim 1, wherein the ethylene-glycidyl methacrylate-vinyl acetate ternary random copolymer is Bond First (registered trademark; a product of Sumitomo Chemical Industries, Ltd.). 3. The manufacturing method according to claim 1, wherein the Bond First is Bond First 7B. 4 Tension treatment under a tension of 10 to 15 g/cm, 20 to 50
The manufacturing method according to claim 1, which is carried out at ℃ for 24 to 48 hours. 5. The manufacturing method according to claim 1, wherein the sheet to be adhered to the fluororesin sheet is coextruded with a thin film of an ethylene-glycidyl methacrylate-vinyl acetate ternary random copolymer.