JPS6353031A - Heat-resistant one-sided coated sheet and manufacture thereof - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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.

(Prior art) Heat-resistant release sheets have come to be widely used for various purposes, and among fluorine-based resins, polytetrafluoroethylene (PTFE) is particularly popular for its non-adhesive, low-friction, and heat-resistant properties. It has advantages such as reducing material loss during mold making, shortening the time required for cleaning, improving work efficiency and product quality, and is used in operations that handle materials that tend to stick together.

When using PTFE, the method of mechanically attaching a PTFE film or sheet to the surface is as follows:
For example, a continuous composite of glass fiber woven fabric and tetrafluoroethylene resin sheet! ! J construction method, JP-A-57-189845
No. etc. have been proposed.

In addition, a method of coating with PTFE enamel is 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. It has drawbacks such as poor abrasion resistance, time-consuming application, and the need to treat burn-in at high temperatures. Next, as a heat-resistant release sheet using PTFE, a method using a glass cloth impregnated with a PTFE dispersion is generally adopted.

However, even in the case of impregnation with such a PTFE dispersion or the pasting of a film as described above, one side of the film is treated with metallic sodium or
Or, after treating it with a method such as corona discharge treatment or styrene graft treatment on the surface, it is pasted with an adhesive, or in the case of rubber, unvulcanized rubber is placed on top of the above-treated PTFE film, heated and pressurized. The method used is to vulcanize the material and adhere it 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, but if the PTFE dispersion is applied thickly at once, Mud cracks occur due to drying, and the burn-in does not go away even after treatment, and it becomes pinholes, so it is not possible to increase the amount of adhesion per coat.
Drying and baking are repeated many times to achieve the desired thickness. Further, from the second time onwards, the dispersion liquid is appropriately diluted and an activator is added as necessary to adjust the dispersion liquid. For this reason, PTFE dispersions, which tend to penetrate easily, are not used, and thickeners such as isopropanol, surfactants, etc. are added to the dispersions to increase the viscosity, generally from 500 to 2,000.
Adjustment to a range of 0 centipoise has also been carried out. However, if the viscosity of the dispersion liquid increases, the phenomenon of penetration into the base fabric to be treated decreases, but on the other hand, handling and workability of the dispersion liquid worsens, and the amount of adhesion to the base fabric increases, resulting in higher costs. In addition, it has the disadvantage that it deteriorates the condition of the treated surface and causes sagging, cracking, foaming, etc.

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. etc., required extremely high skill, and was not easy to handle. Furthermore, in cases where the above-mentioned impregnated double-sided treatment is applied, when performing post-processing such as adhesive treatment or adhesion treatment on the back side, it is difficult to adhere or remove the adhesive layer unless complicated processing such as corona discharge treatment is performed. there were. In this way, impregnating double-sided treatment has been conventionally adopted as a method for obtaining non-adhesive properties of PTFE-based liquids, but it requires time and effort in processing and handling such as subsequent adhesive treatment, and the non-adhesive properties However, only one side is used,
It was expensive and uneconomical. For this reason, there has been a desire for a heat-resistant release sheet in which a PTFE dispersion is efficiently layered on only one side at low cost.

Furthermore, the reason why single-sided PTFE dispersions could not be obtained through processing using PTFE dispersions is that PTFE is supplied as powder, film, or low-viscosity aqueous dispersions, all of which have high melting points. Therefore, when producing products that are smooth and have strong adhesion between woven or knitted fabrics or sheets and resin, it is necessary to bake them at a high temperature of about 380'C, but in the case of powders and films, it is necessary to bake them at high temperatures and pressures. This is because it requires pressure bonding to the base fabric, and in the case of an aqueous dispersion, its low viscosity causes it to penetrate into the back side of the woven or knitted base fabric.

For this reason, for example, Japanese Patent Application Laid-open No. 59-14950.

A method for manufacturing a polytetrafluoroethylene coated cloth has been proposed, and here a double-sided dissimilar coating of PTFE and a single-sided coating are disclosed. This method requires a complicated coating mechanism and device, such as installing a device such as a slit applicator and controlling the amount of the PTFE dispersion coating composition applied. In addition, even if such a mechanism and apparatus are used, the viscosity of the PTFE dispersion coating composition is 50 centivoise or less, for example, commercially available PTF without the addition of a thickener.
E. It is difficult to use an aqueous dispersion because of its good permeability into cloth, and the range of selection of the viscosity of the composition is limited.

Therefore, even if single-sided coating is possible, it is disadvantageous in terms of equipment, handling, workability, cost, etc.
This method cannot be said to be economical or efficient compared to single-sided coating with a TFE 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 coated 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. do. 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, fully flexible fibers, and polyimide fibers. W consisting of heat-resistant organic fibers such as polyester fibers, aromatic polyamide fibers, aromatic polyester fibers, and combinations thereof
A knitted base fabric is suitable. Alternatively, nonwoven fabrics or other sheets made of these materials may be used.

The above-mentioned heat-resistant base fabric is baked at approximately 250°C to 500°C after being coated with the water-dispersed fluororesin composition, which is a condition that does not cause deterioration of physical properties due to deformation or thermal decomposition during the process. , these can be selected as appropriate.

Next, in the present invention, in addition to a homopolymer of tetrafluoroethylene, a copolymer having polytetrafluoroethylene as a main component can be used as the water-dispersed fluororesin composition. These aqueous dispersions are coated on the woven or knitted base fabric made of the heat-resistant fibers by repeating the coating, drying, and baking processes many times. In addition, if necessary,
Thickeners made of one or more water-soluble polymers such as polyalkylene oxide resins can be appropriately selected and used, and inorganic materials such as alumina and titanium can also be added to the dispersion. can.

In addition, in the present invention, the filler used in the packing treatment on one or both sides of the heat-resistant base fabric requires conditions that do not cause deterioration of physical properties during the baking process on the base fabric. Copolymerized elastomers of ethylene tetrafluoride, propylene hexafluoride, and vinylidene difluoride are dissolved in organic solvents and adjusted to high viscosity, or high-viscosity products are prepared by adding inorganic and organic substances as binders to inorganic substances such as alumina and titanium oxide. Using a viscous material, etc., the surface of the base fabric is coated to form a packing layer. Furthermore, a water-dispersed fluororesin composition whose viscosity has been adjusted in advance to have a high viscosity can also be used as the packing 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, hexafluoropropylene, and divinylidene difluoride. A filling layer 7 is formed by applying a highly viscous filler 5 made by dissolving a copolymerized elastomer or the like in an organic solvent, and filling the voids 6 of the warp threads 3 and weft threads 4.

Next, the surface of the packing layer 70 is coated with a water-dispersed fluorine-based resin composition 8 such as an aqueous PTFE dispersion, and then a coating layer 9 which is dried and fired is deposited thereon.

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 2
Even though the viscosity may be adjusted to a lower level in the second coating, since the packing layer 7 formed on the surface is present,
The conventional problem of the composition 8 permeating or leaching out to the back side of the base fabric due to capillary action has been solved, and there are no operational obstacles such as penetration of the fluorine-based resin composition 8 to the back side of the base fabric 2. 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. .

In addition, as shown in FIG. 2 (after coating not only one side but both sides of the filling eyebrows 7), a coating layer 9 of the water-dispersed fluorine-based resin composition 8 is formed on one of the sides, or It is also possible to provide the packing layer 7 only on one side, and form the rit layer 9 of the resin composition 8 on the other side.Furthermore, if necessary, the packing layer 7 to be filled may be formed on one side of the surface relatively. When the composition 8 is formed in a rough state, the viscosity of the composition 8 can be increased by adjusting the viscosity with a thickener such as those described above. A filler material such as alumina can be added, and in the case of a copolymerized elastomer, it can be vulcanized to make it insoluble, infusible, etc.
Alternatively, heat resistance, oil resistance, and strength can be improved.

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 passed from an unwinding roll 10 to an accumulating device 11, and after the wrinkles of the base fabric 2 are removed by a wrinkle smoothing roll 12, a guide roll 1
3 and then introduced into the feed roll 14. Next, the base fabric 2 is run horizontally while being placed on a bed 15, and the filler 5 is coated with a knife doctor 16 to form a packing layer 7. Next, while running the base fabric 2 in the horizontal direction, it is dried in the drying oven 17 in the first chamber and the drying oven 18 in the second chamber.
A firing process is performed in a firing furnace 19 in the chamber. Subsequently, the base fabric 2 that has been treated as described above is led to the cooling section 20, and the air cooling section 2
1 and a water cooling section 22, and then wound onto a winding roll 23.

In the method of the present invention, as described above (while running the heat-resistant base fabric 2 in the horizontal direction, the packing layer 7 with the filler 5 is first applied using a knife coater through a pretreatment process such as smoothing out wrinkles). Next, a water-dispersed fluorine-based resin composition 8 is formed on one or both sides of the wound base fabric 2, but in both cases, the filling layer 7 with the filler 5 is formed. There is an advantage that the same apparatus can be used for coating, and the coating process can be carried out efficiently by setting processing conditions such as drying and baking as appropriate using the same apparatus.

Therefore, in the method of the present invention, the packing layer 7 can be efficiently formed with the filler 5 on one or both sides,
Furthermore, since the water-dispersed fluororesin composition 8 of any viscosity can be used to coat one side of the resin composition 8, the resin composition 8 having a relatively low viscosity can be used to coat one side.
The conventional problems associated with coating processes of this type, which involve multiple or multiple coatings, can be completely eliminated. 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 Commercially available glass glass, 130g/n? , using the medium 105 mark and a filler having the following composition, using the apparatus shown in Figure 3, and coating the upper side of the glass cloth while running the cloth in the horizontal direction. Drying was carried out at 100° C. to 160° C. in the drying oven in the first chamber, and at 250° C. to 300° C. in the drying oven in the second chamber at a speed of 10 m/min. The adhesion amount was 25g/r+ (.Subsequently, in the next firing furnace in the third chamber, the temperature was 250°C to 320°C.
After the firing process was carried out at C, it was cooled in a cooling section and wound up on a winding roll.

Filler compounded fluororubber Viton (DuPont) 100 parts by weight Vulcanizing agent diakNci3 (〃) 1 Gold urine oxide MgO5 1 volume Agent MEK
200 Next, using the same apparatus shown in FIG. 3, a water-dispersed fluorine-based resin composition, TEFLON
30-J (manufactured by DuPont Mitsui Fluorochemicals), the viscosity was adjusted to 15 to 20 centipoise, and coating was performed using a knife coater. Subsequently, while running the cloth horizontally, the first chamber, 150'c The coating process was repeated 4 times under the processing conditions of 200 °C in the second chamber, 300 °C to 370 °C in the third chamber, and a speed of 10 m/min to form a coating layer with a coating weight of 23 g / m. did.

The obtained heat-resistant base fabric has non-adhesive and flat f on one front side.
The coating layer of the fluorine-based resin composition with excellent properties was laminated on the filling layer coated with the filler and was strongly fixed, and no cracks, foaming, etc. were observed. On the other hand, on one side of the back side, the glass cloth fabric was exposed as it was, and on the back side, there was no penetration, seepage, sagging, foaming, etc. of the aqueous dispersion that had been repeatedly coated on one side of the front 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 that could be subsequently subjected to adhesive or adhesive processing on the back side.

(Effects of the Invention) According to the present invention, conventional impregnating double-sided coating treatment or double-sided heterogeneous or single-sided vlFFt that involves a complicated mechanism in a vertical system
This treatment has been improved, and only one side of the heat-resistant fiber base fabric is coated with a PTFE water-based dispersion that has excellent non-adhesive and low-friction properties! , layers can be applied efficiently and strongly.

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. It is extremely efficient because it can be used repeatedly. Furthermore, there is little loss of actual products, and since processing necessary for subsequent adhesion or adhesive treatment can be omitted on one side, it is possible to obtain a heat-resistant single-sided coated sheet suitable for various uses at an industrially advantageous low cost.

[Brief explanation of drawings]

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 coating sheet body, 2... Heat-resistant fiber base fabric, 3... Warp, 4... Weft, 5... Filler, 6... Void, 7... . . . Closing layer, 8. Water-dispersed fluororesin composition, 9. Coating layer, 10. Unwinding roll, 11. Ackinim device, 12. Wrinkle smoothing roll, 13. ...Guide roll, 14...Feeding roll, 15...Bed, 16...Knife doctor,
17.18...Drying oven, 19...Calcining oven, 20...
- Cooling section, 21... Air cooling section, 22... Water cooling section, 23
...Take-up roll, Figure 1

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 packing 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 water-dispersed fluororesin composition. 2) After forming a packing layer that can prevent the penetration of the water-dispersed fluororesin composition on one or both sides of a woven or knitted 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.