JP2534959B2 - Fluorine fiber laminate manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thick filter material having water repellency, chemical resistance, heat resistance and porosity using a tetrafluoroethylene resin fiber sheet.

[0002]

2. Description of the Related Art Conventionally, there are natural fibers, synthetic fibers, glass fibers, metal fibers, resin films, metal foils, and porous ceramics as this type of filter material. For example, a filter material manufactured by sintering is put on the market. Recently, there is a demand for thick laminates depending on the properties of the filter material to be filtered and the filtering conditions. As a conventionally proposed filter material, synthetic fiber materials such as glass fiber, polypropylene and polyester fiber are known, but these are inferior in heat resistance and chemical resistance. On the other hand, a fluororesin is a material having excellent heat resistance and chemical resistance, but it is difficult to obtain a fiber because it has poor processability and cannot be melt-spun. Therefore, tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin (PFA), tetrafluoroethylene / hexafluoropropylene copolymer resin (FEP), tetrafluoroethylene / hexafluoropropylene / perfluoroalkoxyethylene copolymer resin Resin (EPE), tetrafluoroethylene / copolymer resin (E
TFE), ethylene trifluoride chloride / ethylene copolymer resin (ECTFE), vinylidene fluoride resin (PVDF),
A heat-fusible fluororesin with a low melting point, such as vinyl fluoride resin (PVF), has been developed.
A non-woven fabric is manufactured and used as a filter material. When these low-melting fluorine-containing filter materials are laminated and hot-pressed for thick processing, there are problems that the pores of the laminated body are closed by fusion and the heat resistance is poor. .

On the other hand, fibers of tetrafluoroethylene resin (PTFE) having heat resistance and chemical resistance are disclosed in, for example, Japanese Patent Publication No. 46-
The stretched fiber is obtained as described in No. 11043, and the woven fabric or nonwoven fabric produced therefrom is used as a filter material. However, although the fiber material has heat resistance, it is heat-shrinkable because it is stretched, so it cannot be used in high-temperature applications or when heat fusion is required. In connection with this, as disclosed in JP-A-3-97993, a sheet is manufactured and put on the market by a wet papermaking method using an unstretched fiber of a tetrafluoroethylene resin, but the maximum thickness of the obtained sheet is which it was not possible the manufacture of laminate is 500μm thick product. Therefore, if thick material is required, fibers of the same diameter, fibers of different diameter,
Alternatively, a sheet in which the fiber size such as the inter-fiber pore diameter of the same diameter and the inter-fiber pore diameter of different diameter and the inter-fiber void are appropriately combined in the thickness direction of the lamination is used. For example, the sheets are laminated in a flat plate shape in the order of the fiber diameter. Alternatively, by stacking sheets in a flat plate shape in the order of the fiber pore size, a thick molded article having different porosities in the thickness direction is obtained. However, these are simply laminated layers, and are a laminate of layers that are independently separated, and the layers are not integrated. Even if an attempt is made to heat-bond a stretched fiber of a tetrafluoroethylene resin for integrating the layers, it is difficult to manufacture because the melting point of the fiber is high and heat shrinkage occurs.
There was a problem that a thick laminated body could not be integrated by using the above fiber.

[0004]

Interlayer bonding is considered to be extremely difficult because the melting temperature is high and it is difficult to integrate the molded product or sheet using the fibers of tetrafluoroethylene resin even if they are heat-sealed. However, a porous thick sheet made of fibers of tetrafluoroethylene resin is eagerly demanded for its appearance because this material is also excellent in chemical resistance. The present invention, the fibers of polytetrafluoroethylene resin as a sheet, the fine diameter fibers are exchange fault, to produce a sheet having a porous and uniform thickness, the plurality are stacked, the interlayer An object of the present invention is to provide a method for manufacturing a molded body which is fusion-bonded and integrated.

[0005]

The present invention SUMMARY OF THE INVENTION In order to achieve the above object, which has been made a result of extensive studies, the sheet by wet-type paper making method tetrafluoroethylene resin fibers viscose matrix To a raw sheet, the raw sheet is sintered at a temperature equal to or higher than the melting point of tetrafluoroethylene tree to give a sintered sheet, and a plurality of the sintered sheets are laminated to have a predetermined thickness. Te was placed between the upper and lower molding plate member, and then pressure ^{10g / cm 2 ~100g / cm 2} , temperature and pressurized and heat-treated under the conditions of a temperature above the melting point of the tetrafluoroethylene resin And a method for producing a fluorofiber laminate, characterized in that the sintered sheets are fused to each other. In carrying out the method, the fluorofiber laminate obtained as described above is further mixed with a melting point of tetrafluoroethylene resin. Treat at the following temperature and leave By virtue of pyrolysis and removal of viscose, it is possible to produce a fluorofiber laminate without residual viscose. Examples of the plate-shaped body for molding referred to in the present invention include stainless steel, glass, aluminum, ceramics,
Flat plate made of concrete, carbon fiber, etc., stencil,
Textiles can be applied. Further, at least vertically to one of the inner surface of the molding die, the heat-resistant separation material which imparts a pattern to the surface of the laminate is interposed can be obtained with patterns fluorine fiber維積layer body. Furthermore, it is also possible to manufacture curved surface-shaped laminates by using upper and lower plate-shaped bodies having convex and concave surfaces of corresponding curvatures.

[0006]

[Function] When a laminate of raw sheets of tetrafluoroethylene resin fibers is placed between the upper and lower molding plates and pressure heating and fusion are performed, the joining contact surface of the sheets is easily melted with fine fibers. also between the fibers by pressurization occurs straight anchor (anchor) effect of locally exchange fault, upon residual viscose carbide thermally decomposed at the time of sintering, although a slight shrinkage progresses, thereby tetrafluoride The fused ethylene resin fibers are fused and the fluorofiber molding is formed. Further, by heating the tetrafluoroethylene resin to a temperature near the melting point of 327 ° C., the micro-Brown activity of the molecule becomes active, which facilitates plastic deformation and the pressure applied to the laminate and the upper and lower molding plate shapes to be used. Laminated articles having various textures can be obtained according to the surface roughness of the body. Further, by interposing a metal net, a woven fabric of glass fiber, or a non-woven fabric as a heat-resistant separator between the molding plate and the laminate, the pattern can be formed on the surface of the laminate.

[0007]

[Example] A 6 mm cut product of fibers (Toyofuron: manufactured by Toyo Fine Chemical Co., Ltd.) obtained from tetrafluoroethylene resin particles using viscose as a matrix was suspended in water at a concentration of 0.05%, and the suspension was wet-machined. Various sheets of 50 to 400 g / m ² obtained by papermaking and drying are processed at 360 ° C.
Was heat-treated for 5 minutes to remove about 90% of viscose to obtain a sintered sheet having the tetrafluoroethylene resin fiber fused thereto. The sintered sheet was used as the raw material sheet of the example of the present invention.

Example 1 As shown in FIG. 1, the above-mentioned raw material has a sintered sheet, that is, a thickness of 0.25 mm, a weight of 190 g / m ² , a density of 0.76 g / cm ³ , and a porosity of 65%. The sintered sheets 2 to 10 are composed of a lower molding plate 1a (made of a polished stainless steel plate having a thickness that does not easily bend under pressure).
The sheet was laminated and placed so that the polished surface was in contact with the sheet. Then, the heat-resistant separate material 11 is placed on the laminated sheet.
As a result, a stainless wire mesh having a wire diameter of 0.2 mm and a mesh size of 40 was superposed, and the upper molding plate-shaped body 1b was pressed against the mesh, and a pressure of 30 g / cm ² was uniformly applied to the laminated sheet. Then 350 ° C with pressure applied to the sheet
Was heated for 3 hours, and after the prescribed heating time had elapsed, it was cooled while maintaining the pressure, and after completion of the cooling, the pressure and the heat-resistant separate material were removed. Thus, the carbonized decomposition product of viscose used as a matrix gives a light brown color, one side is smooth with a polished steel plate, and one side has fine irregularities due to a wire mesh, thickness 2 mm, weight 1700 g / m ² , density 0.87 g / A laminated product of tetrafluoroethylene resin fibers having a cm ³ porosity of about 60% was obtained.

This laminated product is a palm made by American PMI
When the pores were measured with a porometer (micropore measuring machine), it was confirmed that the pore diameter had an average value of 20 μm and had a normal distribution. To test delamination, a Strograph Universal Testing Machine was used. TAPPI No, 19
When a delamination test was carried out in accordance with the delamination strength test method specified in -77, delamination between layers did not proceed, and the test piece broke first. In addition, the laminated cross section of the laminated product was observed with a microscope, but it was impossible to distinguish between the laminated products.

Example 2 As shown in FIG. 2, the same sintered sheet as in Example 1 was used as a raw material. That is, the fiber diameter is 20 μm and the thickness is 0.
15 mm, weight 125 g / m ² , density 0.83 g / cm
One sintered sheet 2 of ^3, fiber diameter 30 [mu] m, 0.2 thickness
5 mm, weight 187 g / m ² , density 0.75 g / cm ³
2 sintered sheets 3, fiber diameter 50 μm, thickness 0.35
A single sintered sheet 4 having a size of mm, a weight of 265 g / m ² , and a density of 0.76 g / cm ³ was placed on the lower molding plate 1a in the same manner as in Example 1. The lower molding plate was a stainless steel plate, and the respective sintered sheets 2 to 4 to be laminated were placed on the polished surface. On the other hand, the lower molding plate 1a
An upper molding plate 1b made of a polished stainless steel plate similar to the above is placed with its polished surface in contact with the sintered sheet surface,
As in Example 1, 40 g / cm ² is uniformly applied to all sheets.
Was applied.

Thus, the pressure of the sheet is applied 350
After heat treatment for 3 hours at ℃, after cooling for a specified time, cooling is performed while maintaining the pressure, after cooling, the upper molding plate 1b is released, and PT for decomposition and removal of the viscose carbonization residue is removed again.
Heat treatment was performed for 24 hours at a temperature of 318 ° C., which is lower than the melting point of FE. Thus, the thickness is 0.85 mm, the weight is 750 g / m ² ,
A PTFE laminated product having a density of about 0.88 g / cm ³ and a porosity of about 60% was smooth on both sides and was pure white. Example 1
When the pores were measured with a Palm porometer in the same manner as above, it was confirmed that the pore size was a porous laminate having an average pore size of 16 μm.

Example 3 As shown in FIG. 3, the same sintered sheet as in Example 1 was used as a raw material. That is, thickness 0.35mm, weight 2
40 g / m ^2, sintered sheet 3 of density 0.69 g / cm ³
5 to 5 are heat-resistant lower separate materials 2a made of glass cloth on the lower molding plate 1a (female mold) having concave surfaces.
It was laminated and placed on it. On the other hand, on the upper surface of the laminated sheet, an upper molding plate 1b made of a stainless steel male mold that fits into the female mold is placed via a heat-resistant upper separate material 2b made of glass cloth, and then 50 g of the laminated sheet is evenly placed on the laminated sheet. A pressure of / cm ² was applied. Then, in the same manner as in Example 1, heat treatment was performed at 350 ° C. for 5 hours while applying pressure, and cooling was performed. Then, heat treatment was carried out at 318 ° C. for 40 hours with the pressure applied and the upper molding plate 1b and the upper heat-resistant separate material 2b removed. Thus, the surface has a curved shape as shown in FIG. 4, an average thickness of 0.9 mm, a weight of 740 g / m ² , and a density of 0.82 g / c.
There was obtained a tetrafluoroethylene resin fiber laminated molding having m ³ and a porosity of about 59%. When the pore distribution was examined with a palm pometer as in Examples 1 and 2, it was confirmed to be porous having an average pore diameter of 40 μm.

[0013]

According to the present invention, a molding plate is used,
A filter material of a tetrafluoroethylene resin fiber sheet having a high melting point and a large thickness could be obtained very easily. Further, the average inter-fiber pore diameter of the sheet is determined by the fiber diameter, and by appropriately laminating single-layer sheets having different raw fiber diameters, heat-pressing, and heat-sealing, the sheet has a desired pore-size distribution and a thickness. It is possible to obtain a molded body that is extremely effective as a filter material having a density gradient structure in the direction, and further, a laminated body of sheets of fibers having the same diameter can provide a molded body having a uniform pore size. In addition to conventional sheet-shaped filter materials, these molded products of tetrafluoroethylene resin fibers can easily provide thick filter materials in various shapes such as plate shape, corrugated shape, arc shape, tubular shape, and square shape. You can

[Brief description of drawings]

FIG. 1 is a sectional view showing a manufacturing process according to a first embodiment.

FIG. 2 is a cross-sectional view showing a manufacturing process according to a second embodiment.

FIG. 3 is a sectional view showing a manufacturing process according to a third embodiment.

FIG. 4 is a perspective view of a molded product obtained in Example 3.

[Explanation of symbols]

 1a Plate-shaped body for lower molding 1b Plate-shaped body for upper molding 2a Heat-resistant lower separate material 2b Heat-resistant upper separate material 2-10 Sintered sheet 11 Heat-resistant separate material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B29L 31:14 D21H 5/20 F

Claims (4)

(57) [Claims] 1. A with a sheet as a raw sheet by screws wet type papermaking method tetrafluoroethylene resin fibers and matrix course, sintering and sintering said biological sheet at a temperature higher than the melting point of the tetrafluoroethylene resin After forming a binding sheet, a plurality of the sintered sheets are laminated so as to have a predetermined thickness and placed between the upper and lower molding plates, and then the pressure is set to 10 g / cm ² to 1.
A method for producing a fluorofiber laminate, characterized in that the sintered sheets are fused with each other by pressurizing and heating at a temperature of 00 g / cm ² and a temperature not lower than the melting point of the tetrafluoroethylene resin. . 2. The fluorofiber laminate obtained by claim 1 is further treated at a temperature not higher than the melting point of the tetrafluoroethylene resin to thermally decompose and remove the remaining viscose. Body manufacturing method. 3. The method for producing a fluorofiber laminate according to claim 1, wherein a heat-resistant separate material for imparting a pattern to the surface of the laminate is provided on the inner surface of at least one of the upper and lower molding plates. A method for producing a fluorofiber laminate, comprising: 4. A method for producing a fluorine-fiber laminate according to claim 1, method for producing a fluorine fiber 維積 layer body, characterized in that it has a convex surface and the concave surface of the corresponding curvature of the molding die.