JPH0574459B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-resistant single-sided coated sheet and a method for producing the same. More specifically, the present invention relates to a heat-resistant single-sided coated sheet in which only one side of a base fabric is coated with a water-dispersed fluororesin composition, and a method for producing the same.

(Conventional technology) Heat-resistant release sheets are becoming widely used for various purposes, and among fluorine-based resins, polytetrafluoroethylene (PTFE) is particularly popular due to its non-adhesive, low-friction, and heat-resistant properties. It has advantages such as reducing material loss during manufacturing, shortening the time required for cleaning, improving work efficiency and product quality, and is used in work that handles materials that are easily scratched.

When using PTFE, methods for mechanically attaching a PTFE film or sheet to the surface include, for example, a continuous manufacturing method for a composite of a glass fiber woven fabric and a tetrafluoroethylene resin sheet;
57-189845 etc. have been proposed. Also, PNFE
Methods of coating enamel are also known, but PTFE
Enamel is used when a thin film is required on a metal surface, and has characteristics such as adhesive strength, heat resistance, and chemical resistance, but on the other hand, it has poor abrasion resistance, is time-consuming to apply, and can be used at high temperatures. There are drawbacks such as the need to perform a baking process. next,
Generally, heat-resistant release sheets using PTFE are
A method using a glass cloth impregnated with PTFE dispersion has been adopted.

However, even in the case of impregnating with PTFE dispersion or pasting the film as described above, one side of the film is treated with metallic sodium, or the film is treated with a method such as corona discharge treatment or styrene graft treatment on the surface. After treatment, paste with adhesive or, in the case of rubber, place unvulcanized rubber on top of the above treated PTFE film.
The method used is to apply heat and pressure to vulcanize and bond at the same time.

(Problems to be Solved by the Invention) In the method using the glass cloth impregnated with PTFE dispersion, the glass cloth is immersed in the dispersion, pulled up, dried, and fired.
If the PTFE dispersion is applied thickly at one time, it will cause pin cracks as it dries and will not disappear even after baking, resulting in pinholes. Repeat baking many times to achieve the desired thickness. Also, 2
After the first dispersion, adjustments are made by appropriately diluting the dispersion and adding an activator if necessary. For this reason, PTFE, which is usually susceptible to penetration,
A dispersion is not used, but a thickening agent such as isopropanol, a surfactant, etc. is added to the powder to adjust the viscosity, generally in the range of 500 to 20,000 centipoise. However, if the viscosity of the dispersion increases, the penetrating development into the treated base fabric will decrease;
On the other hand, handling and workability of the dispersion liquid deteriorates, and the amount of adhesion to the base fabric increases, which not only increases costs, but also deteriorates the condition of the treated surface, causing sagging, cracking, foaming, etc. There are some difficulties.

In this way, PTFE dispersion-impregnated glass cloth is formed by impregnating, drying, and baking the PTFE dispersion many times, but it does not cause penetration to other surfaces of the base fabric, leaching, sagging, cracking, or foaming. It is easy to cause such problems, requires extremely high skill, and is not easy to handle. Furthermore, in cases where the above-mentioned double-sided impregnating treatment is applied, when performing post-processing such as adhesive treatment or adhesion treatment on the back side, adhesion or lamination is difficult if complicated processing such as corona discharge treatment is performed. Such impregnating double-sided treatment has been conventionally adopted as a method for obtaining non-stick properties of PTFE dispersion liquids, but it requires trouble in processability and handling such as subsequent adhesive treatment, and the non-stick properties are also difficult to obtain on one side. However, the cost was high and it was not economical. For this reason, there has been a desire for a heat-resistant release sheet in which a PTFE dispersion is layered on only one side in a cost-effective manner.

In addition, as mentioned above, the reason why one-sided products could not be obtained by processing using a PTFE dispersion liquid is that
is supplied as a powder, film, or low-viscosity aqueous dispersion, and all of them have high melting points, so when making products that are smooth and have strong adhesive strength between woven or knitted fabrics or sheets and resins, approximately 380% It is necessary to bake at a high temperature of °C, but in the case of powder or film, it is necessary to press it to the woven or knitted fabric base fabric at high temperature and pressure, and in the case of aqueous dispersion, it is necessary to bake it to the woven or knitted fabric base fabric because of its low viscosity. This is because there was a problem that it penetrated to the back side of the paper.

For this reason, for example, a method for manufacturing a polytetrafluoroethylene coated cloth has been proposed in Patent Application No. 59-149500, which discloses coating of different types of PTFE on both sides and coating on one side. It requires a complicated application mechanism and equipment, such as installing a device such as a slit applicator in contact with the surface of the heat-resistant fabric rising in the vertical direction, and controlling the amount of the PTFE dispersion coating composition applied.
In addition, even if such mechanisms and devices are used, PTFE
It is difficult to use a dispersion coating composition with a viscosity of 50 centipoise or less, such as a commercially available aqueous PTFE dispersion without the addition of a thickener, because of its good permeability into fabrics; etc. The selection range is limited. Therefore, even if single-sided coating is possible, equipment, handling, workability,
From a cost perspective, this cannot be said to be an economical and efficient method suitable for coating one side with a PTFE dispersion.

The present invention was achieved as a result of various studies in order to solve the above-mentioned conventional problems as well as various problems in single-sided processing. It is an object of the present invention to provide a heat-resistant single-sided sheet in which a packing layer capable of preventing penetration of substances is formed and one side of the base fabric is coated with a water-dispersed fluorine-based resin composition, and a method for producing the same. . Another object of the present invention is to easily and efficiently produce a single-sided coated sheet with excellent non-adhesiveness and smoothness, in which a woven or knitted base fabric made of heat-resistant fibers is coated on one side with a water-dispersed fluororesin composition. It's about trying to get something at a low cost.

The heat-resistant fibers used in the present invention can be made of inorganic and organic fibers or combinations thereof, such as heat-resistant inorganic fibers such as glass fibers, carbon fibers, asbestos fibers, metal fibers, polyimide-based fibers, etc. Woven or knitted fabrics made of heat-resistant organic fibers such as fibers, aromatic polyamide fibers, aromatic polyester fibers, and combinations thereof are suitable. Alternatively, nonwoven fabrics or other sheets made of these materials may be used.

The above-mentioned heat-resistant base fabric has conditions that do not cause deterioration of physical properties due to deformation or thermal decomposition even during a baking process at approximately 250°C to 500°C after being coated with a water-dispersed fluororesin composition. It can be selected as appropriate.

Next, in the present invention, the water-dispersed fluororesin composition includes a homopolymer of tetrafluoroethylene,
A copolymer containing polytetrafluoroethylene as a main component can be used. These aqueous dispersions are coated on the woven or knitted base fabric made of the heat-resistant fibers by repeating coating, drying, and baking processes many times. Furthermore, if necessary, a thickener containing one or more water-soluble polymers responsive to polyalkylene oxide resin may be appropriately selected and used, and an inorganic material such as alumina or titanium may be added to the dispersion. It can also be added to.

In addition, in the present invention, the filler used for filling one or both sides of the heat-resistant base fabric includes:
Conditions that do not cause deterioration of physical properties are required in the baking process with the base fabric. A material with adjusted viscosity or a high viscosity material made by adding inorganic and organic materials as a binder to an inorganic material such as alumina or titanium oxide is used to coat the surface of the base fabric so as to form a plugging layer. Furthermore, a moisture fluorine-based resin composition whose viscosity has been adjusted in advance to a high viscosity can also be used as the filling layer.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially enlarged schematic diagram of a heat-resistant single-sided coated sheet according to the present invention, and FIG. 2 is another embodiment.

In FIG. 1, 1 is a heat-resistant single-sided coated sheet body, and a heat-resistant fiber base fabric 2 is made up of warp threads 3 and weft threads 4, and one side of its surface is coated with tetrafluoroethylene,
A filling layer 7 is formed by applying a high viscosity filler 5 made by dissolving a copolymer elastomer of propylene hexafluoride and vinylidene difluoride in an organic solvent to fill the voids 6 of the warp 3 and weft 4. has been done. Next, the surface of the packing layer 7 is coated with a water-dispersed fluorine-based resin composition 8 such as PTFE aqueous dispersion, and then a coating layer 9 which is dried and fired is deposited. .

With this configuration, one side of the surface of the heat-resistant fiber base fabric 2 is coated with the low-viscosity water-dispersed fluorine-based resin composition 8, and the viscosity may be adjusted to be even lower in the second coating. Since the packing layer 7 formed on the surface is present, the conventional problem of the composition 8 penetrating or exuding through capillary action to the back side of the base fabric is solved, and the fluorine-based resin composition is also improved in terms of operation. The impediment to the permeation response to the back side of the base fabric described in No. 8 can be completely prevented. Therefore, even if one side of the front surface is coated multiple times, penetration into the back side will not occur, and there is no need to use a thickener to adjust the viscosity of the dispersion to a high range. .

Further, as shown in FIG. 2, after coating not only one side but also both sides with the basis weight layer 7, a coating layer 9 of the polydispersed fluorine-based resin composition 8 is formed on one of the sides, or It is also possible to provide the filling layer 7 only on one side and form the coating layer 9 of the resin composition 8 on the other side. Furthermore, if necessary, if the filling layer 7 to be filled is formed in a relatively rough state on one side of the surface, the composition 8 whose viscosity has been adjusted with a viscosity increasing agent as described above may be combined as appropriate. You can also use In addition, depending on the packing layer 7, a filler material such as magnesia or alumina can be added, and in the case of a copolymer elastomer, it can be vulcanized to make it insoluble, infusible, etc. or improve heat resistance, oil resistance, and strength.

Next, FIG. 3 is a schematic explanatory diagram of an apparatus showing an embodiment of the method of the present invention. In FIG. 3, the heat-resistant base fabric 2 is transferred from the unwinding roll 10 to the Akiyum device 11.
After the wrinkles are removed from the base fabric 2 by a wrinkle smoothing roll 12, the base fabric 2 is introduced into a feed roll 14 via a guide roll 13. Next, the base fabric 2 is run horizontally while being placed on the bed 15, and the filler 5 is coated with a knife doctor 16 to form a filling 7. Next, while running the base fabric 2 in the horizontal direction, it is fed through the drying furnace 17 in the first chamber and the drying furnace 18 in the second chamber, and is then fired in the firing furnace 19 in the third chamber. Let's do it. Subsequently, the base fabric 2 which has been treated as described above is led to a cooling section 20, cooled in an air cooling section 21 and a water cooling section 22, and wound onto a winding roll 23.

In the method of the present invention, as described above, the heat-resistant base fabric 2 is run in the horizontal direction and undergoes a pre-treatment preparation process such as smoothing out wrinkles, and then the packing feed 7 with the filler 5 is first layered using a knife coater. be done. Next, a water-dispersed fluororesin composition 8 is formed on one or both sides of the wound base fabric 2, but in both cases, the same equipment used to form the packing layer 7 with the filler 5 described above is repeated. It has the advantage of being usable, and the coating process can be carried out efficiently by using the same equipment and appropriately setting processing conditions such as drying and firing.

Therefore, in the method of the present invention, it is possible to efficiently form the plugging layer 7 with the filler 5 on one or both sides, and furthermore, with the filler 5 on either side, a water-dispersed fluorine-based material of any viscosity can be used. Since resin composition 8 can also be applied for coating treatment, the conventional problems in this type of coating treatment process in which coating is performed once or many times using resin composition 8 having a relatively low viscosity can be completely avoided. It can be resolved. Further, the method of the present invention is characterized in that desired processing conditions can be set in the above-mentioned apparatus and coating processing can be carried out efficiently by repeatedly using the same apparatus.

(Example) An embodiment of the present invention will be described below.

Example 1 Using commercially available glass cloth, 130 g/m ² and width 105 cm, and with a filler having the following composition, using the apparatus shown in Fig. 3, while running the cloth horizontally, After coating the top side of the glass cloth, the drying oven in the first room
℃~160℃, 250℃~300℃ in the second drying oven
Drying was carried out at a temperature of 10 m/min. The amount of adhesion is
It was 25g/ ^m2 . Subsequently, in the firing furnace in the third chamber, firing treatment was performed at 250° C. to 320° C., then cooled in a cooling section, and wound onto a winding roll.

100 parts by weight of filler-containing fluorinated rubber Viton (DuPont) Vulcanizing agent diak No. 3 (DuPont) 1 part by weight Metal oxide MgO 5 parts by weight Solvent MEK 200 parts Next, the same apparatus shown in Figure 3 was used. ,
Using a water-dispersed fluorine-based resin composition, TEFLON30-J (manufactured by Mitsui Dupont Fluorochemicals), a viscosity of 15 to
Adjust to 20 centipoise, coat with a knife coater, and then run the cloth horizontally in the first chamber, at 150°C, in the second chamber,
The coating process was repeated four times under processing conditions of 200°C, third chamber, 300°C to 370°C, and speed of 10 m/min to form a coating layer with a coating weight of 23 g/m ² .

The obtained heat-resistant base fabric has a coating layer of a fluororesin composition with excellent non-adhesiveness and smoothness on one front side, which is laminated to a filling layer coated with a filler and is strongly fixed to the surface, preventing cracks. No foaming or the like was observed. On the other hand, the glass cloth fabric was left exposed on one side of the back side, and no signs of penetration, seepage, sagging, foaming, etc. of the aqueous dispersion which had been repeatedly coated on one side of the front side were observed on the back side.

In this way, a heat-resistant, single-sided coated sheet was obtained that had non-adhesive properties and low friction properties on one side of the front side, and was in the form of a bare cloth suitable for subsequent adhesive or adhesive processing on the back side.

(Effects of the Invention) According to the present invention, it is possible to improve the impregnating double-sided coating treatment, or the double-sided dissimilar or single-sided coating treatment involving a complicated vertical system, and to It is possible to efficiently and strongly apply a PTFE aqueous dispersion coating layer that has excellent non-adhesion and low friction properties.

In addition, since a filling layer is formed with voids filled in advance on one or both sides, there is no risk of inconvenient permeation or sagging of the aqueous dispersion, and the equipment and operation are simple, and the same equipment can be used. Since it can be used repeatedly, it is possible to omit the processing necessary for subsequent adhesion or adhesion when it is extremely single-sided, making it an industrially advantageous, low-cost, heat-resistant single-sided coated sheet suitable for appropriate applications. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partial enlarged schematic diagram of a heat-resistant single-sided coated sheet according to the present invention, FIG. 2 is another embodiment, and FIG. 3 is a schematic explanatory diagram of an apparatus showing an embodiment of the method of the present invention. DESCRIPTION OF SYMBOLS 1...Heat-resistant single-sided coated sheet body, 2...Heat-resistant fiber base fabric, 3...Warp, 4...Weft, 5...Filler, 6...Void, 7...Filled layer, 8... ... Water fluorine resin composition, 9 ... Coating layer, 10 ... Unwinding roll, 11 ... Akiyum device, 12 ... Wrinkle smoothing roll, 13 ... Guide roll, 14 ...
Feed roll, 15... Bed, 16... Knife doctor, 17, 18... Drying oven, 19... Baking furnace, 20... Cooling furnace, 21... Air cooling section, 22...
Water cooling section, 23... winding roll.

Claims (1)

[Scope of Claims] 1. A packing layer that can prevent the penetration of a water-dispersed fluororesin composition is formed on one or both sides of a woven or knitted base fabric made of heat-resistant fibers, and a layer that can prevent the penetration of a water-dispersed fluororesin composition is formed on one side of the base fabric. A heat-resistant single-sided coated sheet characterized by being coated with a dispersed fluorine-based resin composition. 2. After forming a packing layer that can prevent the penetration of the water-dispersed fluorine-based resin composition on one or both sides of a woven or knitted fabric base fabric made of heat-resistant fibers, horizontally with one side of the base fabric as the upper surface. 1. A method for producing a heat-resistant single-sided coated sheet, characterized in that one side of the upper surface of the base fabric is coated with a water-dispersed fluorine-based resin composition.