JPS6364303B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composite material obtained by firing a combination of a heat-resistant organic polymer fiber structure and a tetrafluoroethylene resin present around the fiber structure and in the pores thereof, and a method for manufacturing the same. When cooking in an oven or microwave, glass cloth impregnated with tetrafluoroethylene resin and baked can be preferably used as a release sheet to prevent food from burning or sticking to containers. This is already known, and special sheets are also available on the market. Although these glass cloth impregnated sheets have non-adhesive properties and mold release properties due to tetrafluoroethylene resin, and maintain high durability, they lack flexibility due to the nature of glass cloth, and aluminum foil It is not suitable for use that involves folding or creating wrinkles, as in the case of . For example, even if you try to wrap ingredients for cooking, this sheet is rigid and will not roll up like aluminum foil, and if you repeatedly bend it like this, the glass fibers will break and the sheet itself will be damaged. The purpose of the present invention is to develop a non-adhesive sheet material that does not have the above-mentioned drawbacks, has high bending strength, and has heat resistance and mechanical strength equivalent to or higher than that of tetrafluoroethylene resin-impregnated glass cloth. It was made in That is, the present invention provides fabrics such as woven fabrics and knitted fabrics,
The present invention provides a composite material obtained by firing a combination of a heat-resistant organic polymer fiber structure including a nonwoven fabric and a tetrafluoroethylene resin present around the fiber structure and in the pores thereof, and a method for producing the same. The composite material of the present invention is generally produced by preparing a tetrafluoroethylene resin as an aqueous or organic dispersion, immersing a heat-resistant fiber structure in this dispersion, and then combining the fiber structure and the tetrafluoroethylene resin. It can be prepared by a method of obtaining a combination of the above, drying it, and firing it. Although the method for producing the combination of the fibrous structure and the tetrafluoroethylene resin is not limited to the above-mentioned method, the immersion impregnation method is usually convenient. The heat resistance of the heat-resistant organic polymer material fiber used in the present invention must be equal to or higher than that of tetrafluoroethylene resin, and therefore its decomposition temperature is 300°C or higher, preferably 350°C or higher. It is necessary. Heat-resistant fiber materials that meet this requirement include aromatic polyamides (for example, Kevler and Nomex from Dupont, Conex from Teijin, and Conex from Monsanto).
(commercially available as Durette). Aromatic polyamides are particularly excellent materials due to their flexibility, heat resistance, fiber-forming properties, etc., but polyamideimide (commercially available as Kermel from Rhodiaceta), polybenzimidazole (Celanese), and polyphenylene Oxide (Glanzstoff
Tenax, Inc.), etc. can also be suitably used. As the tetrafluoroethylene resin, a tetrafluoroethylene homopolymer or a tetrafluoroethylene copolymer containing at least 75% by weight of tetrafluoroethylene can be used. In the case of the copolymer, the monomer other than tetrafluoroethylene is one selected from the group consisting of ethylene, propylene, vinyl fluoride, vinylidene fluoride, propylene hexafluoride, polyfluoroalkyl vinyl ether, and chlorotrifluoroethylene. Preferably, it is a species or two or more monomers. The amount of resin deposited by impregnation depends on the concentration of the dispersion liquid and also on the viscosity of the liquid. That is, even if dispersions of the same concentration are used, the amount of impregnation increases as the viscosity increases. The temperature for firing needs to be higher than the melting point of the tetrafluoroethylene resin. Therefore, firing is usually at 300°C or higher, preferably at 350°C.
It is carried out in the range of ~400℃. However, depending on the type of heat-resistant fiber, its melting point or decomposition temperature may be lower than the above temperature, and in this case, if the impregnated fiber is baked in an electric furnace as usual, the heat-resistant fiber itself will melt and decompose. Such conventional firing methods cannot be used because they cause staining or coloration. Therefore, in such a case, after drying the combination, it is recommended to place it in a far-infrared oven set at a temperature as high as it can withstand and hold it for about 0.5 to 10 minutes. By this method, the fluororesin present around the fibrous structure and in the pores is melted and sintering is achieved. The fluororesin used in this case is preferably a tetrafluoroethylene copolymer resin with a low melting point. impregnation,
By repeating the drying and firing steps two or more times and layering the composite, the surface of the composite can be smoothed and the gloss can be improved. In the sheet-like composite material of the present invention prepared in this way, the pores and surface of the heat-resistant fiber structure are filled with or coated with the tetrafluoroethylene resin, so that the surface has a heat-resistant property. It has the properties of tetrafluoroethylene resin rather than the original properties of fibers, and has water and oil repellency, non-adhesiveness, mold releasability, etc. Furthermore, this sheet is more flexible than impregnated glass cloth, and has excellent durability even when used repeatedly, such as bending, twisting, and knotting. It also has excellent heat resistance, and the above characteristics are not impaired even under high temperature heating of 200 to 250°C. Since the composite material sheet of the present invention has the above-mentioned properties, it is particularly useful as a release packaging material for cooking or for various seat belts, but it is also widely used as a release sheet material in the plastic industry, rubber processing industry, or confectionery industry. can be used. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 A 60% concentration aqueous tetrafluoroethylene resin dispersion ("Polyflon Dispersion D-1" manufactured by Daikin Industries, Ltd.) was poured into an enamel tray to a depth of 5 cm, and a 40 x 40 cm A nonwoven fabric (thickness: 60 μm) of aromatic polyamide fiber “Conex” (manufactured by Teijin Ltd.) was dipped and pulled up. During this time, the ambient temperature is 20±2℃
Keep it. A sizing rod is used to remove excess dispersion liquid adhering to the surface of the nonwoven fabric, and to even out the adhesion to the nonwoven fabric and smooth the surface. Pinch one side of the nonwoven fabric and hang it at room temperature for 10 minutes, then dry it using an infrared lamp at 130-150℃ for about 10 minutes, then put it in an electric furnace and heat and bake it at 360-380℃ for 1-2 minutes. Fusing the fluorinated ethylene resin. The resulting composite material is brown colored. The impregnated nonwoven fabric thus obtained is compressed by passing it through a hot roll at about 300 to 320°C to remove surface wrinkles,
Product. Furthermore, the steps of impregnating the above product with the aqueous tetrafluoroethylene resin dispersion, firing, and roll compression are repeated once again. Table 1 shows various physical properties of products according to the present invention in which the impregnation process is performed once or twice, nonwoven fabrics that are not impregnated, and sheets that are impregnated once under the same conditions as above. The measurement method for each physical property in Table 1 is as follows. Contact angle: using a goniometer manufactured by Elma Optical,
The contact angle with pure water is measured at room temperature. Tensile strength and elongation: 20 samples with a width of 10 mm and a length of 50 mm
Tensile at a speed of mm/min to determine the load (g) and elongation (%) at cutting. Tear strength: Make a vertical cut in the center of a 10 mm wide and 50 mm long sample to the middle of 25 mm, hold both sides divided by the cut, and calculate the strength when tearing under the same conditions as when measuring tensile strength. Bending durability: After repeating 360° bending 10 times at the same point in the center of the sample, measure the tensile strength and elongation. Non-adhesiveness: Place the sample sheet on a hot plate, bake egg whites on it, and check the peelability after cooking.

[Table] Example 2 An aqueous dispersion of tetrafluoroethylene and hexafluoropropylene copolymer (“Neoflon Dispersion ND-1” manufactured by Daikin Industries, Ltd.) with a concentration of 52% by weight was placed in an enamel tray. Put it in a depth of 5cm and put it in this
15cm x 15cm aromatic polyamide fiber "Conex"
(manufactured by Teijin Ltd.) woven fabric (thickness 125μ) is soaked and pulled up. During this time, keep the ambient temperature at 20±2℃. A sizing rod is used to remove excess dispersion liquid adhering to the surface of the fabric, and to make the adhesion uniform to the fabric and smooth the surface. After pinching one side of the woven fabric and hanging it for 10 minutes at room temperature, dry it for about 10 minutes at 130 to 150℃ using an outside line lamp.
The product is placed in a far-infrared oven whose temperature is set to 0.degree. C., and is irradiated with far-infrared rays for about 3 to 5 minutes to fuse the tetrafluoroethylene-hexapropylene copolymer. The woven fabric obtained in this way is hardly colored. The obtained impregnated woven fabric is compressed by passing it through a heated roll at 180-230°C to remove surface wrinkles. More impregnation, firing,
The compression operation is repeated once again to produce a product. The non-adhesive properties of the thus obtained composite material according to the present invention were tested using the method shown in Example 1.
My grades were excellent.

Claims (1)

[Scope of Claims] 1. A composite material obtained by firing a combination of a heat-resistant organic polymer fiber structure and a tetrafluoroethylene resin present around the structure and in the pores. 2. The composite material according to item 1 above, wherein the heat-resistant organic polymer material is a polyphenylene amide resin. 3. According to any one of the above items 1 or 2, wherein the tetrafluoroethylene resin is a tetrafluoroethylene homopolymer or a tetrafluoroethylene copolymer containing at least 75% by weight of tetrafluoroethylene. composite materials. 4. A method for producing a composite material, which comprises impregnating a heat-resistant organic polymer fiber structure with a tetrafluoroethylene resin, drying it, and then firing it by far infrared irradiation.